JP6577274B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and is suitable for application to, for example, a color electrophotographic printer (hereinafter also referred to as a color printer).

  A conventional color recording apparatus includes an image forming unit provided with one photoconductor for forming a black image, and a color image forming unit provided with three photoconductors for forming yellow, magenta, and cyan images. However, these photoconductors are arranged in contact with the conveyor belt. In addition, the color recording apparatus is provided with two cam shafts, gears, motors, and the like, each having an eccentric cam fixed to each end thereof, below the frame of the color image forming unit. When recording a monochrome image on a medium, the color recording apparatus drives a motor to rotate four eccentric cams together with two cam shafts to push up the lower four corners of the frame, thereby forming a color image from the conveyor belt. The three photosensitive members of the unit are separated from each other, and wear of these three photosensitive members and the conveyance belt is avoided to extend the life (for example, see Patent Document 1).

JP-A-9-281770 (3rd page, 4th page, FIG. 1 and FIG. 2)

  However, in the conventional color recording apparatus, the lower four corners of the frame of the color image forming unit are pushed up to separate the photoconductor from the conveyance belt, so that the configuration for separating the photoconductor from the conveyance belt is complicated. It was.

  The present invention has been made in consideration of the above points, and an object of the present invention is to propose an image forming apparatus capable of simplifying the configuration for separating the image carrier from the transfer portion.

In order to solve such a problem, in the present invention, a housing main body, a hinge, an opening / closing cover attached to the housing main body via the hinge so as to be opened and closed, and an image carrier that carries a developer image rotate. a plurality of image forming units provided so as to be, in the casing body, is opposed to allow supporting one side portion side and the other side portion of the plurality of image forming units, a plurality of a plurality of mounting positions A pair of first and second unit support portions for mounting the image forming unit and a plurality of image forming units supported by the first and second unit support portions and mounted at a plurality of mounting positions . is placed in contact with the image bearing member, a transfer unit for transferring the developer image on the plurality of image bearing members, respectively provided on one side of the plurality of image forming units, the first state being operated individually And switchable to second state A scan and a stopper, a hinge provided at one edge side of each other of the casing main body and a cover, to allow opening and closing the other edge of the cover to the casing body, the housing body portion and closing with arranging the first unit support portion to the other edge side of the cover, by arranging the second unit support portion on one edge side of the casing body and a cover, the first and second unit supporting section, either also in supporting the image forming unit, a stopper is positioned at the other edge side of the casing body and a cover, when the stopper is in the first state, supports the image forming unit at the mounting position, the stopper is a second state Oh Rutoki, supports the image forming unit at the separation position where the image bearing member is disengaged from the transfer unit, the stopper is an image forming unit is mounted to the mounting position is supported by the first and second unit supporting section Condition In the operated, switched by displacing the image forming unit from the mounting position to the distant position from the first state to the second state.

Accordingly, in the present invention, when the image forming unit is mounted between the first and second unit support portions, the image forming unit is lifted by hand from between the first and second unit support portions or removed. Even without this, the stopper can be easily operated by opening the open / close cover with respect to the housing main body , and by this operation, the image forming unit is displaced from the mounting position to the separation position to separate the image carrier from the transfer portion. be able to.

Further, in the present invention, an image forming unit on which an image carrier that carries a developer image is rotatably provided, and is disposed so as to be able to support one side and the other side of the image forming unit, A pair of first and second unit support portions for mounting the image forming unit at the mounting position, and an image carrier when the image forming unit is supported by the first and second unit support portions and mounted at the mounting position. And a transfer portion for transferring the developer image on the image carrier and one side of the image forming unit so as to be able to rotate and switch between the first state and the second state. A first stopper, a second stopper provided on the other side of the image forming unit so as to be rotatable together with the first stopper and switched to the first state and the second state, and one side of the image forming unit The first unit that supports the side The holding portion is provided with a first engaging portion that can be engaged with the first stopper, and a second unit support portion that supports the other side of the image forming unit so as to be engageable with the second stopper. When the first stopper and the second stopper are not engaged with the first engagement portion and the second engagement portion in the first state by the first and second unit support portions, When the image forming unit is supported at the mounting position and the first stopper and the second stopper are engaged with the first engaging portion and the second engaging portion in the second state, the image carrier is moved from the transfer portion to the image carrier. The image forming unit is supported at a separated position, and the image forming unit is detachably mounted at the mounting position by being inserted into and pulled out from one surface of the first and second unit support portions, and the first stopper and the second stopper are mounted. From the first state, one side of the first and second unit support parts When the image forming unit is rotated to the second state in the predetermined rotational direction opposite to the insertion side when the image forming unit is mounted, the image forming unit is engaged with the first engaging portion and the second engaging portion. The image forming unit is supported at the separation position by the first and second unit support portions by lifting from the mounting position to the separation position. Further, in the present invention, the image carrier that carries the developer image is arranged so as to be able to support the one side and the other side of the image forming unit that can be rotated via the shaft. And a pair of first and second unit support portions for mounting the image forming unit at the mounting position, and an image when the image forming unit is supported by the first and second unit support portions and mounted at the mounting position. One of the transfer unit that is arranged to contact the carrier and transfers the developer image on the image carrier, one side of the image forming unit, and the first unit support that supports the one side, A stopper provided so as to be switchable between the first state and the second state, and an engaging portion provided on the other side of the one side surface and the first unit support portion of the image forming unit are provided, and the stopper is in the first state. so The image forming unit is supported at the mounting position by the first and second unit support portions without being engaged with the engagement portion, and the first and second unit support portions are engaged with the engagement portion in the second state. The image forming unit is supported at a separation position that separates the image carrier from the transfer unit , a fitting groove is formed in the other end of the image carrier shaft in the image forming unit, and the image forming unit is mounted on one surface of the first unit support unit. A first support portion that supports one end portion of the shaft is formed as one side surface of the image forming unit at the position and the separation position, and the other side surface side of the image forming unit is mounted on the one surface of the second unit support portion. As a result, a second support portion was formed to support the other end portion of the shaft by fitting with the fitting groove .

Therefore, in the present invention, the image forming unit is supported at the separated position by the first and second unit support portions only by switching the first stopper and the second stopper of the image forming unit from the first state to the second state, and the transfer portion. The image carrier can be separated from the image forming unit, and at the time of separation from the mounting position of the image forming unit, rotation in a predetermined rotation direction that is opposite to the insertion side when the first stopper and the second stopper are mounted. As a result, the image forming unit can be smoothly lifted from the mounting position to the separation position by reversing the mounting movement path between the first and second unit support portions without being caught by the shaft. In the present invention also, by the one side of the stopper of the image forming unit from a first state only by switching to the second state, the image from the transfer unit by supporting the image forming unit at the separation position to the first and second unit supporting section The carrier can be separated, and at the mounting position and the separation position, the fitting groove of the shaft is fitted into the second support part of the second unit support part, so that the space between the first and second unit support parts is reached. The image forming unit can be positioned and supported so that the unit center position substantially coincides with the center position between the support plates .

According to the present invention, when the image forming unit is mounted between the first and second unit support portions, the image forming unit is grasped by hand and lifted or removed from between the first and second unit support portions. Even if it is not, the opening and closing cover can be opened with respect to the housing main body, the stopper can be easily operated, the image forming unit can be displaced from the mounting position to the separation position , and the image carrier can be separated from the transfer portion. Thus, an image forming apparatus that can simplify the configuration for separating the image carrier from the transfer portion can be realized.

According to the invention, the image forming unit is supported at the separated position by the first and second unit support portions only by switching the first stopper and the second stopper of the image forming unit from the first state to the second state. The image carrier can be separated from the transfer portion, and when separated from the mounting position of the image forming unit, in a predetermined rotation direction that is opposite to the insertion side when the first stopper and the second stopper are mounted. , The image forming unit can be smoothly lifted from the mounting position to the separated position by reversing the moving path during mounting between the first and second unit support portions without being caught on the shaft. An image forming apparatus capable of simplifying the configuration for separating the image carrier from the transfer portion can be realized. Further, according to the present invention, the image forming unit is supported by the first and second unit support portions at the separated positions by simply switching the stopper on the one side surface of the image forming unit from the first state to the second state. from it is possible to separate the image carrier Rutotomoni, in the mounted position and the distant position, by fitting the fitting groove of the shaft to the second support portion of the second unit support portion, the first and second unit support The image forming unit can be positioned and supported so that the unit center position substantially coincides with the center position between the support plates , and thus the configuration for separating the image carrier from the transfer unit can be simplified. An image forming apparatus can be realized.

1 is a schematic side view showing an internal configuration of a color printer according to the present invention. 2 is a schematic cross-sectional view illustrating a configuration of an image forming unit. FIG. FIG. 6 is a schematic perspective view for explaining an attachment mechanism of the image forming unit to the printer housing. FIG. 3 is a schematic perspective view illustrating a configuration of a left end portion of the image forming unit. It is a rough-line perspective view which shows the structure of a left side unit support plate. FIG. 6 is a schematic side view for explaining the mounting (1) of the image forming unit to the printer housing. FIG. 6 is a schematic rear view for explaining the mounting (2) of the image forming unit to the printer housing. FIG. 3 is a schematic side view illustrating a configuration of a stopper provided in the image forming unit. FIG. 6 is a schematic side view for explaining the separation (1) of the photosensitive drum from the transfer belt by the stopper. FIG. 10 is a schematic rear view for explaining the separation (2) of the photosensitive drum from the transfer belt by the stopper. FIG. 6 is a schematic rear view for explaining a gap when the image forming unit is mounted at the mounting position. FIG. 6 is a schematic rear view for explaining an inclination when the image forming unit is attached to a separation position. It is a rough-line perspective view which shows the structure (1) of an image forming unit. It is a rough-line perspective view which shows the structure (2) of an image forming unit. It is a rough-line perspective view with which it uses for description of rotation operation (1) of the right stopper of an image forming unit. It is a rough-line perspective view with which it uses for description of rotation operation (2) of the right stopper of an image forming unit. FIG. 6 is a schematic side view for explaining the mounting (1) of the image forming unit to the printer housing. FIG. 6 is a schematic rear view for explaining the mounting (2) of the image forming unit to the printer housing. FIG. 10 is a schematic side view for explaining the separation (1) of the photosensitive drum from the transfer belt by the rotation operation of the right stopper. FIG. 10 is a schematic rear view for explaining the separation (2) of the photosensitive drum from the transfer belt by the rotation operation of the right stopper. It is a rough-line perspective view used for description of rotation operation of a right stopper. It is a rough-line rear view which shows the structure of the stopper provided in the image forming unit by other embodiment. It is a rough-line top view which shows the structure (1) of the stopper provided in the right unit support plate by other embodiment. It is a rough-line rear view which shows the structure (2) of the stopper provided in the right unit support plate by other embodiment. It is a rough-line side view which shows the internal structure of the color printer by other embodiment.

The best mode for carrying out the invention (hereinafter, also referred to as an embodiment) will be described below with reference to the drawings. The description will be given in the following order.
(1) First embodiment (2) Second embodiment (3) Other embodiments

(1) First Embodiment (1-1) Internal Configuration of Color Printer In FIG. 1, 1 denotes a primary transfer type color printer according to the first embodiment as a whole. The color printer 1 has, for example, a substantially square box type printer housing 2 whose front end is the right end surface in the drawing. Incidentally, in the following description, when the color printer 1 is viewed from the front of the printer housing 2, the direction above the color printer 1 indicated by the arrow a1 in the figure is also referred to as the printer upward direction. The direction opposite to the upward direction of the printer is also referred to as the downward direction of the printer, and these are also collectively referred to as the upward and downward direction of the printer when it is not necessary to distinguish them. In the following description, the direction in front of the color printer 1 indicated by the arrow b1 in the figure when the color printer 1 is viewed from the front of the printer housing 2 is also referred to as the front direction of the printer. The direction opposite to the front direction of the printer is also referred to as the rear direction of the printer. Furthermore, in the following description, the left direction of the color printer 1 indicated by the arrow c1 in the figure when the color printer 1 is viewed from the front of the printer housing 2 is also referred to as the printer left direction. The direction opposite to the left direction of the printer is also referred to as the right direction of the printer.

  The printer housing 2 is configured, for example, such that the top plate portion is attached to the housing main body portion 2A below the top plate portion as an openable opening / closing cover 2B that can be opened and closed. The open / close cover 2B includes a medium delivery unit 2BX that delivers a print medium 5 on which a print image is formed, and a medium discharge unit that ejects the print medium 5 from the printer housing 2 to the medium delivery unit 2BX. An outlet 2BY is formed. In the printer housing 2, an image forming unit 7 for forming a print image on the surface of the print medium 5 is disposed at the center, and a plurality of print media 5 can be loaded at the lower end. A cassette 8 and a feed roller 9 that feeds the print media 5 from the medium cassette 8 one by one are arranged. The image forming unit 7 includes, for example, four image forming units 10 to 13, four LED (Light Emitting Diode) heads 14 to 17 as exposure units, a transfer unit 18, and a fixing unit 19. ing. The four image forming units 10 to 13 are detachably mounted side by side along the rear direction of the printer with respect to the housing main body 2A. The four LED heads 14 to 17 are attached to the front end portions of the four head support portions 14A to 17A that are arranged along the rear direction of the printer on the inner surface of the opening / closing cover 2B, and are attached to the four image forming units. 10 to 13 one by one in order. The four image forming units 10 to 13 are respectively provided with black and cyan as developers on the surfaces of the photosensitive drums 20 to 23 as image carriers provided so as to be rotatable in one rotation direction indicated by an arrow d1 in the drawing. , Magenta and yellow toners form toner images as developer images for four colors, and are arranged in the order corresponding to black, cyan, magenta and yellow, for example, in the rear direction of the printer. .

  The transfer unit 18 transfers the toner images on the surfaces of the photosensitive drums 20 to 23 onto the surface of the print medium 5, and includes a belt driving roller 25 provided to be rotatable in another rotation direction opposite to the one rotation direction, and An endless transfer belt 27 is stretched around the driven roller 26, and the surface of the transfer belt 27 is brought into contact with the four photosensitive drums 20 to 23. The transfer unit 18 has four transfer rollers 28 to 31 arranged at positions facing the four photosensitive drums 20 to 23, and these transfer rollers 28 to 31 are in contact with the back surface of the transfer belt 27. The fixing unit 19 fixes the toner image on the surface of the printing medium 5 by heating and pressing. Incidentally, in the printer casing 2, a medium supply transport unit 32 that forms a medium supply transport path for transporting the print medium 5 fed from the medium cassette 8 to the image forming unit 7 is disposed at the front lower end. Has been. In the printer casing 2, a medium discharge transport unit 33 that forms a medium discharge transport path for transporting the print medium 5 fed from the fixing unit 19 to the medium discharge port 2BY is disposed at the rear upper end. ing.

  In the printer housing 2, for example, a printer control unit (not shown) such as a microprocessor that performs overall control of the entire color printer 1 is provided. When forming a color print image, the printer control unit controls each part in the printer housing 2 to feed out the print media 5 one by one from the media cassette 8 and form the image via the medium supply conveyance path. Transport to part 7. At this time, for example, the printer control unit controls the four LED heads 14 to 17 in accordance with the color components of black, cyan, magenta, and yellow of the color image to be printed based on the image data, thereby four images. The forming units 10 to 13 form electrostatic latent images on the surfaces of the photosensitive drums 20 to 23 and develop the electrostatic latent images with toner to form black, cyan, magenta, and yellow toner images. In addition, the printer control unit conveys the print medium 5 by the four photosensitive drums 20 to 23 and the transfer belt 27, and sequentially transfers the toner images on the surfaces of the four photosensitive drums 20 to 23 onto the surface of the print medium 5. After being transferred so as to overlap, the fixing unit 19 fixes the toner image on the surface of the print medium 5 to form a color print image, and the print medium 5 is connected to the medium discharge port 2BY via the medium discharge conveyance path. To the medium delivery unit 2BX. In addition, the printer control unit drives and controls each unit in the printer housing 2 in the same manner as described above when forming a monochrome print image, thereby feeding out the print media 5 from the medium cassette 8 one by one, and a medium supply conveyance path. To the image forming unit 7. However, at this time, the printer control unit controls one LED head 14 in accordance with the black color component of the monochrome image to be printed based on the image data, so that the photosensitive drum 20 of one image forming unit 10 is controlled. An electrostatic latent image is formed on the surface, and the electrostatic latent image is developed with toner to form a black toner image. Further, the printer control unit transfers the toner image on the surface of the photosensitive drum 20 to the surface of the printing medium 5 while conveying the printing medium 5 by one photosensitive drum 20 and the transfer belt 27, and then uses the fixing unit 19. A toner image is fixed on the surface of the print medium 5 to form a monochrome print image. The print medium 5 is conveyed to the medium discharge port 2BY through the medium discharge conveyance path and discharged to the medium delivery unit 2BX. .

(1-2) Configuration of Image Forming Unit Next, the configuration of the four image forming units 10 to 13 will be specifically described. However, the four image forming units 10 to 13 are similarly configured except that toners of any one color of black, cyan, magenta, and yellow are used so as not to overlap each other for forming a toner image. Therefore, the configuration of one image forming unit 10 out of the four image forming units 10 to 13 will be described below, and the description of the configuration of the other three image forming units 11 to 13 will be omitted. As shown in FIG. 2, the image forming unit 10 includes a unit housing 40 having a substantially J-shaped box shape, for example. The unit housing 40 has a substantially flat box-type toner container in which an internal space is appropriately divided, a substantially U-shaped box-shaped toner image forming unit 40A is provided at the lower end, and a toner 41A is accommodated in the upper front end. A portion 40B and a substantially wedge-box type toner recovery portion 40C are provided.

  In the toner image forming portion 40A, a slit 40AT is formed at the bottom of the groove 40AS, and an opening 40AV is formed at a position facing the groove 40AS in the bottom plate portion 40AU. The unit housing 40 is supported by a left side plate and a right side plate so as to be rotatable in one rotation direction through a shaft (hereinafter also referred to as a drum shaft) in which the photosensitive drum 20 is parallel to the horizontal direction of the printer. In the toner image forming portion 40A, the upper portion of the surface of the photosensitive drum 20 is opposed to the slit 40AT, and the lower portion of the surface is protruded to the outside from the opening 40AV. The unit housing 40 supports the charging roller 42 as a charging unit by a left side plate and a right side plate so as to be rotatable in the other rotation direction through a shaft parallel to the horizontal direction of the printer, and in the toner image forming unit 40A. The surface of the charging roller 42 is pressed on the upstream side in the rotation direction with respect to the upper portion of the surface of the photosensitive drum 20. Further, the unit housing 40 supports the developing roller 43 as a developer carrying member by the left side plate and the right side plate so as to be rotatable in the other rotation direction through a shaft parallel to the horizontal direction of the printer. The surface of the developing roller 43 is pressed to the downstream side in the rotational direction from the upper portion of the surface of the photosensitive drum 20. Further, the unit housing 40 supports a supply roller 44 as a developer supply unit by a left side plate and a right side plate via a shaft parallel to the left and right rear sides of the printer so as to be rotatable in the other rotation direction, and a toner image forming unit 40A. The surface of the supply roller 44 is pressed against the surface of the developing roller 43. Furthermore, in the unit housing 40, a root portion of a toner blade 46 as a developer thickness regulating portion is fixed to a blade support portion 45 provided in the toner image forming portion 40A, and a tip portion of the toner blade 46 is connected to a developing roller. The surface 43 is pressed to a predetermined position between the pressing position to the photosensitive drum 20 and the pressing position to the supply roller 44.

  The unit housing 40 is provided with a cleaning blade 47 for removing the toner 41A remaining after the transfer of the toner image from the surface of the photosensitive drum 20 as the collected toner 41B in the toner image forming unit 40A. The leading end is pressed against the surface of the photosensitive drum 20. Then, the unit housing 40 removes the collected toner 41B removed from the surface of the photosensitive drum 20 by the cleaning blade 47 from the vicinity of the cleaning blade 47 in the toner image forming unit 40A through, for example, the inside of the right side plate, into the toner collecting unit 40C. The toner is conveyed and collected to the toner collecting unit 40C via the collected toner conveying path formed over the entire area and the conveying bodies 48 and 49 arranged in the collected toner conveying path. Further, the unit housing 40 supports one of the three toner stirring portions 50 to 52 by the left side plate and the right side plate so as to be rotatable in one rotation direction in the toner storage portion 40B via the shaft. At the same time, the other two are supported by these shafts so as to be rotatable in the direction of one rotation in the vicinity of the supply roller 44 in the toner image forming section 40A. The unit housing 40 is provided with a toner supply port 40BX communicating with the toner image forming unit 40A at the lower end of the toner storage unit 40B.

  By the way, the photosensitive drum 20 has a gear (hereinafter also referred to as a drum gear) fixed to a predetermined position inside the left side plate, for example, at the left end of the drum shaft. Further, the developing roller 43, the supply roller 44, and the three toner stirring portions 50 to 52 are similarly fixed to the left end portion of each shaft. Further, the unit casing 40 rotatably supports a plurality of intermediate gears on the inner surface of the left side plate, whereby the unit casing 40 is appropriately connected to the gear of the photosensitive drum 20 via a plurality of intermediate gears. 43, the supply roller 44, and the gears of the three toner stirring units 50 to 52 are sequentially connected. The printer housing 2 is provided with a unit drive motor for driving the image forming unit 10 and a drive gear connected to the output shaft of the unit drive motor. When the image forming unit 10 is mounted on the printer housing 2, the drum gear is engaged with the drive gear. Further, when the image forming unit 10 is mounted on the printer housing 2, a corresponding power source provided in the printer housing 2 is electrically connected to the shafts of the charging roller 42, the developing roller 43, and the supply roller 44. Is done. When the open / close cover 2B is closed with the image forming unit 10 thus mounted in the printer housing 2, the corresponding LED head 14 is inserted into the groove 40AS, and the LED head 14 is fired. The exposed exposure light can be irradiated to the surface of the photosensitive drum 20 through the slit 40AT.

  Therefore, the image forming unit 10 rotates the photosensitive drum 20 in one rotation direction together with the drum gear and rotates the developing roller 43 and the supply when the driving gear rotates according to the operation of the unit driving motor when the print image is formed. The roller 44 is rotated in the other rotation direction. In addition, the image forming unit 10 rotates the three toner stirring units 50 to 52 in one rotation direction in conjunction with the rotation of the photosensitive drum 20 in one rotation direction, and stirs the toner 41A. The toner 41A is taken into the toner supply location in the toner image forming unit 40A. Further, since the charging roller 42 is pressed against the photosensitive drum 20, the image forming unit 10 rotates the charging roller 42 so as to rotate in the other rotation direction according to the rotation of the photosensitive drum 20 in one rotation direction. In addition, a DC voltage having a predetermined voltage value is applied to the image forming unit 10 from power supplies corresponding to the charging roller 42, the developing roller 43, and the supply roller 44, respectively. As a result, the image forming unit 10 charges the surface of the photosensitive drum 20 to a predetermined potential for forming an electrostatic latent image by the charging roller 42 while rotating the photosensitive drum 20 in one rotation direction. The portion is exposed by exposure light emitted from the LED head 14 to form an electrostatic latent image. At this time, the image forming unit 10 supplies and carries the toner 41A on the surface of the developing roller 43 while being charged with the supply roller 44 rotating together with the developing roller 43, and the toner roller 46 allows the developing roller 43 to move. The excess toner 41A having a predetermined thickness or more is removed from the surface to regulate the thickness. The image forming unit 10 develops the electrostatic latent image on the surface of the photosensitive drum 20 with the toner 41 </ b> A on the surface of the developing roller 43 to form a toner image on the surface of the photosensitive drum 20. For example, the transfer roller 28 corresponding to the image forming unit 10 is applied with a DC voltage having a predetermined voltage value from a power source to a shaft. Accordingly, at this time, the transfer roller 28 can transfer the toner image from the surface of the photosensitive drum 20 onto the surface of the printing medium 5 conveyed by the photosensitive drum 20 and the transfer belt 27.

(1-3) Mounting Mechanism of Image Forming Unit to Printer Housing Next, a mounting mechanism of the image forming units 10 to 13 to the printer housing 2 will be described. However, the four image forming units 10 to 13 have the same mounting configuration. Therefore, in the following, a configuration for mounting one image forming unit 10 out of the four image forming units 10 to 13 will be described together with a configuration for mounting on the printer housing 2 side, and the other three units. A description of the configuration for mounting the image forming units 11 to 13 is omitted. As shown in FIGS. 3 and 4, in the image forming unit 10, the unit housing 40 has a left side 40 </ b> DA and a right side 40 </ b> EA (that is, outer surfaces of the left side plate 40 </ b> D and the right side plate 40 </ b> E) substantially flat and substantially parallel. Is formed. The drum shaft 20A is formed with a fitting groove 20AX having a predetermined depth and width over a circumference at a predetermined position near the tip of the left end portion. The unit housing 40 has a predetermined length as a support portion for supporting the left end portion and the right end portion of the drum shaft 20A from the lower rear end portion of each of the left side surface 40DA and the right side surface 40EA for mounting on the printer housing 2 side. By projecting, the fitting groove 20AX is positioned outside the left side surface 40DA. Further, the unit housing 40 has a columnar left-side posture regulating projection 40DB and a right-side posture regulating projection for regulating the mounting posture of the image forming unit 10 with respect to the printer housing 2 at the upper front ends of the left side surface 40DA and the right side surface 40EA. It has been planted. Further, the unit housing 40 is provided with a rib-like left gap restriction portion 40DC and a right gap restriction portion projecting from the central rear ends of the left side face 40DA and the right side face 40EA. The left gap restricting portion 40DC and the right gap restricting portion are each formed in a flat rectangular shape with the upper end surfaces being substantially parallel to the left side surface 40DA and the right side surface 40EA of the unit housing 40, and the lower end portion is below the surface. It is formed in a substantially wedge shape that inclines so that the protruding height from the left side 40DA and the right side 40EA gradually decreases toward the side. In the following description, the surfaces of the upper end portions of the left gap restriction portion 40DC and the right gap restriction portion are also referred to as the left restriction portion surface and the right restriction portion surface, and the lower ends of the left gap restriction portion 40DC and the right gap restriction portion. The surface of the portion is also referred to as a left restricting portion inclined surface and a right restricting portion inclined surface. The unit housing 40 has an arcuate gear engagement notch 40DE formed at a position directly below the left end of the drum shaft 20A on the lower surface of the left side plate 40D.

  On the other hand, as shown in FIG. 3 and FIG. 5, a pair of left unit support plate 55 and right unit support plate 56 are formed on the printer housing 2 with a predetermined flat surface 55A, 56A. They are arranged almost parallel at intervals. The printer housing 2 is configured such that the transfer unit 18 is flattened between the belt driving roller 25 and the driven roller 26 in the transfer belt 27 by the lower end portions of the one surface 55A, 56A of the left unit support plate 55 and the right unit support plate 56. The part is supported almost horizontally. 3 shows the left unit support plate 55 and the right unit support plate 56, but the rear end portion of the right unit support plate 56 is omitted for easy understanding of the configuration. . The left unit support plate 55 is selected to have a predetermined thickness that is slightly thinner than the width of the fitting groove 20AX of the drum shaft 20A. Further, the left unit support plate 55 and the right unit support plate 56 are provided with plate-like left side projecting portions 55B and right side projecting portions 56B that project outward from one surface 55A, 56A as engaging portions at the upper ends, respectively. . On one surface 55A of the left unit support plate 55, there are four left and right guide portions 55C that are vertically long and extending in the vertical direction from the left projecting portion 55B to the vicinity of the support position of the transfer unit 18 along the rear direction of the printer. Are formed at predetermined equal intervals. The four left guide portions 55C guide the mounting of the image forming units 10 to 13 to the printer housing 2 via the left end portions of the drum shafts 20A of the photosensitive drums 20 to 23, respectively, and the width of the central portion is the same. A predetermined width wider than the diameter of the drum shaft 20A is selected. Each of the four left guide portions 55C is selected so that the width of the upper end portion gradually increases from the center portion to the left overhang portion 55B, and the upper end of the left guide portion 55C extends from the upper side to the left end portion of the drum shaft 20A. It is a guide open end that can be inserted and pulled out upward. Further, each of the four left guide portions 55C has a lower end portion formed as a notch with respect to one surface 55A, and the width thereof is selected to be a predetermined width substantially equal to the diameter of the fitting groove 20AX smaller than the diameter of the drum shaft 20A. Thus, it is a shaft support end portion that supports the left end portion of the drum shaft 20A. In the following description, the tip of the shaft support end is also referred to as a guide tip. The left unit support plate 55 rotatably supports the four drive gears 57 connected to the output shaft of the unit drive motor described above below the guide tips of the four left guide portions 55C. .

  In addition, on one surface 55A of the left unit support plate 55, four left engagement portions 55D that are substantially notched from the left projecting portion 55B to a predetermined position on the support position side of the transfer unit 18 are left guide portions 55C. It is formed on the front side. The four left side engaging portions 55D are respectively engaged with the left side attitude regulating protrusions 40DB of the image forming units 10 to 13. Therefore, each of the four left engaging portions 55D is selected to have a predetermined width wider at the upper end than the diameter of the left posture restricting protrusion 40DB, and the upper end inserts the left posture restricting protrusion 40DB from above, Moreover, it is an engagement part open end which is pulled out upward. Further, each of the four left engagement portions 55D has a lower end width that is selected to have a predetermined width substantially equal to the diameter of the left posture restriction protrusion 40DB, and a protrusion engagement end portion that engages with the left posture restriction protrusion 40DB. It has become. Further, on one surface 56A of the right unit support plate 56, the image forming units 10 to 10 with respect to the printer housing 2 are disposed at positions facing the four left guide portions 55C via the right end portions of the drum shafts 20A of the photosensitive drums 20 to 23. Four right guide portions 56 </ b> C for guiding the mounting of 13 are formed. The four right guide portions 56C are formed as notches having a substantially square shape on one surface 56A of the right unit support plate 56, and the width of the shaft support end portion is a predetermined width substantially equal to the diameter of the drum shaft 20A. Except that the four left guide portions 55C have substantially the same configuration. Further, one surface 56A of the right unit support plate 56 has the same configuration as that of the four left engaging portions 55D and engages with the right posture regulating protrusions of the image forming units 10 to 13. Four right engaging portions 56D are formed.

  Therefore, as shown in FIGS. 3, 6, and 7, when the image forming unit 10 is mounted, the printer housing 2 places the image forming unit 10 on the toner image forming unit, for example, diagonally below the toner collecting unit 40C. With the posture 40A positioned, the left unit support plate 55 and the right unit support plate 56 are brought closer to the left unit support plate 56 from above, and the left end and right end of the drum shaft 20A are inserted into the left guide unit 55C and right guide unit 56C from the guide open end. . In addition, when the image forming unit 10 is inserted between the left unit support plate 55 and the right unit support plate 56, the printer housing 2 has a left end portion and a right end portion of the drum shaft 20A in the left guide portion 55C and the right guide portion 56C. Is moved to the shaft support end. At this time, when the image forming unit 10 is inserted to some extent between the left unit support plate 55 and the right unit support plate 56, the printer housing 2 releases the left posture restriction protrusion 40DB and the right posture restriction protrusion 40EB. Inserted from the end into the left engaging portion 55D and the right engaging portion 56D. When the image forming unit 10 is further pushed between the left unit support plate 55 and the right unit support plate 56, the bottom of the fitting groove 20AX of the drum shaft 20A is set to the guide tip of the left guide portion 55C. While making it abut, it is made to fit in a shaft support end part, and the right end part of the said drum shaft 20A is abutted against the guide front-end | tip of the right side guide part 56C. As a result, the printer housing 2 supports the drum shaft 20A substantially parallel to the left-right direction of the printer at the shaft support ends of the left guide portion 55C and the right guide portion 56C. In addition, the printer housing 2 is engaged with the left posture restriction protrusion 40DB and the right posture restriction protrusion 40EB inserted into the protrusion engagement ends of the left engagement portion 55D and the right engagement portion 56D. As a result, the printer housing 2 makes one rotation around the drum shaft 20A with respect to the image forming unit 10 via the left posture restriction protrusion 40DB and the right posture restriction protrusion 40EB by the left engagement portion 55D and the right engagement portion 56D. This prevents the body from falling down so as to rotate in the direction (also in the other direction of rotation) and maintains an almost upright posture. In this way, the printer housing 2 mounts the image forming unit 10 at the mounting position between the left unit support plate 55 and the right unit support plate 56 and brings the surface of the photosensitive drum 20 into contact with the surface of the transfer belt 27. The drive gear 57 can be engaged with the drum gear 58 by entering the gear engagement notch 40DE.

  Incidentally, the image forming unit 10 has a height from the left side surface 40DA to the surface of the left side restricting portion (hereinafter, also referred to as a left side gap restricting portion height) and a height from the right side surface 40EA to the right side restricting portion surface (hereinafter, referred to as the left side restricting portion surface). This is also referred to as the right-side gap regulating portion height). As a result, the image forming unit 10 has the gap between the one surface 55A of the left unit support plate 55 and the surface of the left restricting portion when mounted at the attachment position by the height of the left gap restricting portion and the right gap restricting portion. The gap between the one surface 56A of the right unit support plate 56 and the surface of the right restricting portion is restricted to be as narrow as possible. Therefore, when the image forming unit 10 is inserted between the left unit support plate 55 and the right unit support plate 56, the printer housing 2 has a center position between the left unit support plate 55 and the right unit support plate 56 (hereinafter, referred to as the “unit position”). If the center position in the width direction of the image forming unit 10 (hereinafter also referred to as the unit center position) is shifted in the left-right direction of the printer from the center position between the support plates), one surface 55A of the left unit support plate 55 The left-side regulating portion inclined surface of the left-side gap regulating portion 40DC and the right-side regulating portion inclined surface of the right-side gap regulating portion 40EC are slid with respect to the upper edge of the upper side and the upper edge 56A of the right-side unit supporting plate 56, The positional deviation of the image forming unit 10 in the left-right direction of the printer can be corrected so as to bring the unit center position closer to the center position. Then, the printer housing 2 is fitted between the left unit support plate 55 and the right unit support plate 56 by fitting the fitting groove 20AX of the drum shaft 20A into the shaft support end of the left guide portion 55C. Can be positioned and mounted so that the unit center position substantially coincides with the center position between the support plates. Note that when the image forming unit 10 is removed, the printer housing 2 is pulled out so as to lift the image forming unit 10 from between the left unit support plate 55 and the right unit support plate 56. It can be easily removed by the reverse procedure. In the following description, the lower side for displacing the image forming unit 10 for insertion between the left unit support plate 55 and the right unit support plate 56 is also referred to as a unit insertion side as appropriate. The upper side that is displaced for extraction from between the left unit support plate 55 and the right unit support plate 56 is also appropriately referred to as a unit extraction side.

  In addition to such a configuration, as shown in FIGS. 8A and 8B, in the image forming unit 10, the unit housing 40 has a substantially prismatic stopper 60 at the upper rear end portion of the right side surface 40EA. The stopper 60 is provided so as to be rotatable in one rotation direction and the other rotation direction via a shaft 61 suspended from the center of the back surface of the stopper 60. Further, the unit housing 40 is provided with a substantially L-shaped rotation range restricting portion 40ED that restricts the rotation range of the stopper 60 at the upper rear corner of the right side surface 40EA. As a result, when the unit casing 40 rotates to the first state in which the stopper 60 is rotated in the other rotational direction to a first state in which the longitudinal direction of the stopper 60 (hereinafter also referred to as the stopper longitudinal direction) is parallel to the vertical direction of the printer, One end of one side of the stopper 60 is abutted against one end of the portion 40ED to stop the rotation. Further, when the unit casing 40 is rotated from the first state to the second state in which the stopper longitudinal direction is parallel to the front-rear direction of the printer from the first state to the one rotation direction, the stopper 60 is disposed on the other end surface of the rotation range restricting portion 40ED. The rotation is stopped by hitting the other end of one side. In this way, the unit housing 40 can be switched to the first state or the second state by rotating the stopper 60 within a rotation range of 90 degrees. For the stopper 60, the thickness from the back surface to the front surface, the width from one side surface to the other side surface, and the length in the stopper longitudinal direction are appropriately selected. Accordingly, as shown in FIGS. 6 and 7, when the image forming unit 10 is inserted between the left unit support plate 55 and the right unit support plate 56 with the stopper 60 in the first state, the stopper 2 By inserting 60 into the right guide portion 56C from the guide open end, the image forming unit 10 can reach the mounting position and be mounted.

  On the other hand, as shown in FIGS. 9 and 10, in the printer housing 2, the image forming unit 10 is lifted to some extent from between the left unit support plate 55 and the right unit support plate 56, or the stopper 60 is removed. When inserted between the left unit support plate 55 and the right unit support plate 56 in the second state, the other end of the other side of the stopper 60 is abutted against the right extension portion 56B on the rear side of the right guide portion 56C. Engage. Accordingly, the printer housing 2 is stopped at a position before the image forming unit 10 reaches the mounting position with respect to the left unit support plate 55 and the right unit support plate 56 (that is, a position on the unit pulling side from the mounting position). Can be attached. When the stopper 60 is engaged with the right extension portion 56B, the printer housing 2 does not reach the mounting position between the left unit support plate 55 and the right unit support plate 56. The surface of the photosensitive drum 20 can be separated from the surface of the belt 27 by a predetermined first distance D1, and the drum gear 58 can be separated from the drive gear 57 without meshing. Incidentally, in the following description, the position where the image forming unit 10 is attached by engaging the stopper 60 with the right-side protruding portion 56B with respect to the left-side unit support plate 55 and the right-side unit support plate 56 is also referred to as a separation position.

  Here, the configuration for separating the photosensitive drum 20 of the image forming unit 10 from the transfer belt 27 will be described more specifically with reference to FIGS. 11 and 12. 11 and 12 both show the image forming unit 10 in a simplified manner. First, as shown in FIG. 11, the left unit support plate 55 and the right unit support plate 56 are arranged so that the image forming unit 10 can be smoothly inserted and removed between them as is apparent from the above description. The forming unit 10 is disposed so as to face each other with an interval slightly wider than the width from the surface of the left restricting portion to the surface of the right restricting portion. When the image forming unit 10 is mounted at the mounting position, the printer housing 2 does not shift the image forming unit 10 in the left-right direction of the printer via the fitting groove 20AX of the drum shaft 20A as described above. By positioning, the right side regulation surface of the left side gap regulating part 40DC is separated from the one surface 55A of the left unit support plate 55 by the minute gap S1 regulated by the left side gap regulating part height H1. As shown in FIG. 12, the image forming unit 10 also has the fitting groove 20AX of the drum shaft 20A formed on the left guide portion 55C even when the stopper 60 is engaged with the right side overhanging portion 56B and attached to the separated position. It is fitted to the shaft support end.

  However, the image forming unit 10 is provided with the stopper 60 for separating the photosensitive drum 20 from the transfer belt 27 only on the right side surface 40EA. For this reason, when the image forming unit 10 is mounted at the separation position, the image forming unit 10 is separated from the right end portion by the gap S1 due to its own weight and play between the fitting groove 20AX of the drum shaft 20A and the shaft support end portion of the left guide portion 55C. In some cases, the upper edge of the left-side restricting portion is abutted against one surface 55A of the left-side unit support plate 55 by tilting so as to lower the left end portion. In this case, the printer housing 2 has the image forming unit 10 in a left-down position, and the engagement position of the stopper 60 with respect to the right extension portion 56B and the engagement of the drum shaft 20A with the shaft support end portion of the left guide portion 55C. The groove 20AX is supported at three positions, that is, the fitting position of the groove 20AX and the contact position of the left regulating portion surface with respect to the one surface 55A of the left unit support plate 55. As a result, although the printer housing 2 separates the right end of the surface of the photosensitive drum 20 from the surface of the transfer belt 27 by the first distance D1, the left end of the surface of the photosensitive drum 20 is a predetermined second distance compared to the right end. Only D2 is positioned on the surface side of the transfer belt 27. At this time, the inclination angle of the drum shaft 20A with respect to the left-right direction of the printer is determined by the contact position of the surface of the left regulating portion with respect to the one surface 55A of the left unit support plate 55 corresponding to the gap S1. The second distance D2 with respect to the first distance D1 is determined according to the inclination angle of the drum shaft 20A with respect to the left-right direction of the printer. In the present embodiment, if the second distance D2 is equal to or greater than the first distance D1, the right end of the surface of the photosensitive drum 20 cannot be separated from the surface of the transfer belt 27, but the left end cannot be separated. Even if the forming unit 10 is tilted when attached to the remote position, the formula (1)

      D1-D2> 0 (1)

The left gap regulating portion height H1 of the left gap regulating portion 40DC is appropriately selected so as to satisfy the condition of making the second distance D2 smaller than the first distance D1 as expressed by the following, and the gap S1 is regulated accordingly. is doing. That is, in the present embodiment, even when the image forming unit 10 is tilted when attached to the separation position, the left end portion can be reliably separated from the surface of the transfer belt 27 together with the right end portion of the surface of the photosensitive drum 20. In order to regulate the gap S1, the left gap regulating portion height H1 is appropriately selected. In the case of this embodiment, for example, when the outer shape of the drum gear 58 fixed to the left end portion of the drum shaft 20A is equal to or larger than the outer shape of the photosensitive drum 20, or when the drive gear 57 has the tooth tip on the upper side of the transfer belt 27 ( In other words, in the case of being provided so as to protrude toward the image forming unit 10 side, the entire surface of the photosensitive drum 20 is reliably separated from the surface of the transfer belt 27 in consideration of the configuration of the drum gear 58 and the drive gear 57. The left gap regulating portion height H1 is appropriately selected so that the drum gear 58 is also reliably separated from the drive gear 57. In the present embodiment, the gap S1 is regulated to about 0.5 [mm], for example, by appropriately selecting the left gap regulating portion height H1. As a result, when the image forming unit 10 is mounted at the separation position, the printer housing 2 separates the entire surface of the photosensitive drum 20 from the surface of the transfer belt 27 and also separates the drum gear 58 from the drive gear 57. With this configuration, in the color printer 1, for example, when forming a color print image on the surface of the print medium 5, the four image forming units 10 to 13 are mounted at individual mounting positions. In the case of forming a monochrome print image on the surface, only the image forming unit 10 corresponding to black is mounted at the mounting position, and the other three image forming units 11 to 13 are mounted at the separated positions. It is possible to prevent the photosensitive drums 21 to 23 of the three image forming units 11 to 13 and the transfer belt 27 from being worn out. In the color printer 1, when a monochrome print image is formed on the surface of the print medium 5, the drum gear 58 is separated from the drive gear 57 in each of the other three image forming units 11 to 13 that are attached to the separation positions. The drum gear 58 and the like as well as the drive gear 57 can be prevented from being wasted.

(1-4) Operation and Effect of First Embodiment In the configuration described above, the color printer 1 rotates the stopper 60 on the right side surface 40EA of each of the four image forming units 10 to 13, respectively, in the first state and It was provided so as to be switchable to the second state. In the color printer 1, a pair of left unit support plate 55 and right unit support plate 56 are disposed in the printer housing 2 with their one surfaces 55 </ b> A and 56 </ b> A facing each other, and the right side unit support plate 56 has a right side at the upper end. The overhanging portion 56B is provided. In the color printer 1, when the image forming units 10 to 13 are inserted between the left unit support plate 55 and the right unit support plate 56 with the stopper 60 in the first state, the stopper 60 is connected to the right projecting portion 56 </ b> B. The image forming units 10 to 13 are mounted at the mounting positions without being engaged, and the surfaces of the photosensitive drums 20 to 23 are brought into contact with the surface of the transfer belt 27. On the other hand, when the image forming units 10 to 13 are inserted between the left unit support plate 55 and the right unit support plate 56 with the stopper 60 in the second state, the color printer 1 projects the stopper 60 to the right side. The insertion of the image forming units 10 to 13 is stopped at a separation position before reaching the mounting position by engaging with the portion 56B.

  Therefore, the color printer 1 can be separated from the left unit support plate 55 and the right unit support plate 56 only by switching the stopper 60 provided on the right side 40EA of the image forming units 10 to 13 from the first state to the second state. The image forming units 10 to 13 are attached to the positions, and the photosensitive drums 20 to 23 can be separated from the transfer belt 27. In the color printer 1, the stoppers 60 are provided on the right side surfaces 40EA of the four image forming units 10 to 13, respectively, so that the image forming units 10 to 13 are located to some extent from between the left unit support plate 55 and the right unit support plate 56. It is possible to easily switch between the first state and the second state by a simple operation of lifting or removing the stopper 60 and manually rotating the stopper 60. That is, the color printer 1 can switch the state of the stopper 60 between the first state and the second state without providing any motor or gear for rotating the stopper 60 of the image forming units 10 to 13. The configuration of the entire separation mechanism for separating the photosensitive drums 20 to 23 from the belt 27 can be greatly simplified, and the size can be reduced as compared with the conventional color recording apparatus. When the color printer 1 forms a monochrome print image on the surface of the print medium 5, only the image forming unit 10 corresponding to black is mounted at the mounting position, and the other three image forming units 11 are mounted at the separated positions. By attaching the thru 13 to the stopper 60, it is possible to prevent the transfer belt 27 from being worn with the photosensitive drums 21 to 23 of the three image forming units 11 to 13. Therefore, the color printer 1 can extend the service life of the other three image forming units 11 to 13 and the service life of the transfer belt 27.

  According to the above configuration, the color printer 1 is provided with the stopper 60 on the right side surface 40EA of the four image forming units 10 to 13 so as to be switchable between the first state and the second state, respectively. Out of the pair of left unit support plate 55 and right unit support plate 56 facing each other for mounting 10 to 13, the right overhanging portion is formed on the upper end of the right unit support plate 56 corresponding to the right side 40EA of the image forming unit 10. When the image forming units 10 to 13 are inserted between the left unit support plate 55 and the right unit support plate 56 with the stopper 60 in the first state, the stopper 60 is not related to the right extension portion 56B. By attaching the image forming units 10 to 13 to the mounting position without mounting them, a photosensitive drum is formed on the surface of the transfer belt 27. When the image forming units 10 to 13 are inserted between the left unit support plate 55 and the right unit support plate 56 with the surfaces 20 to 23 in contact with the stopper 60 in the second state, the stopper 60 is extended to the right side. The image forming units 10 to 13 are stopped at a separated position in front of the mounting position and engaged with the portion 56B. Thus, the color printer 1 simply switches the stopper 60 provided on the right side surface 40EA of the image forming units 10 to 13 from the first state to the second state between the left unit support plate 55 and the right unit support plate 56. The image forming units 10 to 13 are attached to the separation positions so that the photosensitive drums 20 to 23 can be separated from the transfer belt 27, and thus the configuration for separating the photosensitive drums 20 to 23 from the transfer belt 27 is remarkably simplified. Can be

  Further, the color printer 1 is arranged so that the entire surface of the photosensitive drums 20 to 23 is separated from the surface of the transfer belt 27 even when the four image forming units 10 to 13 are inclined when they are attached to the separation positions. The left side gap regulating portion 40DC having a predetermined left side gap regulating portion height H1 for regulating the gap S1 with the one surface 55A of the left unit support plate 55 is provided on the left side surface 40DA of each of the image forming units 10 to 13. As a result, the color printer 1 can reliably separate the entire surface of the photosensitive drums 20 to 23 from the surface of the transfer belt 27 even when the four image forming units 10 to 13 are inclined when they are attached to the separation position. it can.

  Further, in the color printer 1, the drum gear 58 is fixed to the left end portion of the drum shaft 20 </ b> A in each of the four image forming units 10 to 13, and the drive gear 57 is provided at a position corresponding to the drum gear 58 on the left unit support plate 55. I made it. The color printer 1 is provided with the left gap regulating portion 40DC having the left gap regulating portion height H1 in consideration of the configuration of the drum gear 58 and the drive gear 57 on the left side 40DA of the four image forming units 10 to 13. . As a result, the color printer 1 can reliably separate the entire surface of the photosensitive drums 20 to 23 from the surface of the transfer belt 27 even when the four image forming units 10 to 13 are inclined when they are attached to the separation positions. In addition, the corresponding drum gears 58 can be reliably separated from the individual drive gears 57.

  Further, the color printer 1 is provided with a right gap regulating portion 40EC that regulates a gap with the one surface 56A of the right unit support plate 56 on the right side 40EA of each of the four image forming units 10 to 13, and together with the right gap regulating portion 40EC. The right-side restricting portion inclined surface and the left-side restricting portion inclined surface are formed at the lower end portion of the left-side gap restricting portion 40DC. Accordingly, the color printer 1 is configured such that when the image forming units 10 to 13 are inserted between the left unit support plate 55 and the right unit support plate 56, even if the unit center position deviates from the center position between the support plates in the left-right direction of the printer. The positional deviation can be easily corrected by the left gap regulating portion 40DC and the right gap regulating portion 40EC. In particular, the color printer 1 separates the entire surface of the photosensitive drums 20 to 23 from the surface of the transfer belt 27 when the four image forming units 10 to 13 are attached to the separation positions (and the drum gear 58 is separated from the drive gear 57). A function of regulating a gap S1 for separating the image forming unit 10 and a function of correcting a positional deviation in the left-right direction of the printer when the image forming units 10 to 13 are inserted between the left unit support plate 55 and the right unit support plate 56. By using the left gap restricting portion 40DC as well, the configuration of the image forming units 10 to 13 can be prevented from becoming complicated for realizing these two functions.

  Further, the color printer 1 is provided with a stopper 60 in each of the four image forming units 10 to 13. Accordingly, when the color printer 1 uses, for example, toners of three colors of cyan, magenta, and yellow to form a color print image that also represents a black color as a mixed color thereof, an image forming unit corresponding to black is used. 10 is attached to the separation position by the stopper 60, and the other three image forming units 11 to 13 are attached to the attachment position, so that the transfer belt 27 together with the photosensitive drum 20 of the image formation unit 10 corresponding to the black is attached. Can be prevented from being worn out. Therefore, the color printer 1 can also extend the service life of the image forming unit 10 corresponding to black. Since the color printer 1 is detachable from the four image forming units 10 to 13, it prints an image forming unit that contains toner of a color other than black, cyan, magenta, and yellow (white, clear, etc.). As used for image formation, it can be mounted at a mounting position or, if appropriate, mounted at a remote position. In addition, the color printer 1 has, for example, one image forming unit 10 mounted at the mounting position and the other three image forming units 10 separated from each other as the image forming unit 10 containing the black toner 41A. Each time the toner 41A of the mounted image forming unit 10 is used up to form a print image, the toner 41A is attached to a separated position, and another image forming unit 10 containing the toner 41A is attached. Instead, the four image forming units 10 can be used in order to form a print image so as to be mounted at the mounting position. As described above, the color printer 1 can arbitrarily select four image forming units used for forming a print image by toner color, and at least two of the selected image forming units have the same color. In the case of containing toner, these can be used in order for forming a print image in the same manner. That is, the color printer 1 stores the black toner 41A in addition to the four image forming units that store different color toners and the combination of the four image forming units 10 that each store the black toner 41A. A total of four image forming units 10 for storing white and clear toner, and two image forming units 10 for storing black toner 41A and magenta toner. A total of four of the two image forming units 12, a total of four of the three image forming units 10 containing the black toner 41A and one image forming unit containing the white (or clear) toner, etc. In addition, the four image forming units can be used for forming a printed image in various combinations. In addition to this, the color printer 1 can attach all the four image forming units 10 to 13 to the separated positions not only when forming a print image but also at the time of factory shipment. Therefore, the color printer 1 can prevent the surface of the photosensitive drums 20 to 23 and the surface of the transfer belt 27 from being deformed by pressing even if the period from the time of shipment from the factory to the start of use by the user is relatively long. it can. As described above, the color printer 1 can be used in various ways because the four image forming units 10 to 13 are detachable and can be individually separated, and the convenience is remarkably improved. be able to.

(2) Second Embodiment (2-1) Internal Configuration of Color Printer Next, a primary transfer type color printer 70 (FIG. 1) according to a second embodiment will be described. However, the color printer 70 according to the second embodiment includes the color printer 1 (FIG. 1) according to the first embodiment described above, and the image generation unit 71 for the left unit support plate 55 (FIG. 3) and the right unit support plate. The four image forming units 72 to 75 are configured in the same manner except that a part of the mounting structure is different from a part of the structure of the right unit support plate. In other words, the color printer 70 according to the second embodiment is partly equipped with the color printer 1 (FIG. 1) according to the first embodiment and the mounting mechanism of the four image forming units 72 to 75 to the printer housing 2. The configuration is the same except for differences. Therefore, regarding the configuration excluding the mounting mechanism of the four image forming units 72 to 75 with respect to the printer housing 2 of the color printer 70 according to the second embodiment, refer to the above description with reference to FIG. The description in is omitted.

(2-2) Mounting Mechanism of Image Forming Unit to Printer Housing Next, a mounting mechanism of the image forming units 72 to 75 to the printer housing 2 will be described. However, the four image forming units 72 to 75 have the same mounting configuration. Therefore, hereinafter, a configuration for mounting one image forming unit 72 out of the four image forming units 72 to 75 will be described, and a configuration for mounting the other three image forming units 73 to 75 will be described. Will not be described. In the following, a configuration of the right unit support plate different from the first embodiment among the left unit support plate 55 and the right unit support plate will be described as a configuration for mounting on the printer housing 2 side. As shown in FIG. 13 and FIG. 14 in which parts corresponding to those in FIG. 2 to FIG. 4 are given the same reference numerals, the image forming unit 72 has a substantially J-shaped box unit housing 80. Except for the left side plate 80A and the right side plate 80B, the image forming units 10 to 13 according to the first embodiment are basically configured in the same manner.

  In this case, the left side plate 80A and the right side plate 80B in the unit casing 80 have substantially the same outer shape as the left side plate 40D and the right side plate 40E of the image forming units 10 to 13 according to the first embodiment, and the left side surface 80AS and The right side surface 80BS is formed to be substantially flat and substantially parallel. The unit housing 80 projects the left end portion and the right end portion of the drum shaft 20A from the lower rear end portions of the left side surface 80AS and the right side surface 80BS. Further, the left side plate 80A is provided with a columnar left side posture restricting projection 80AT and a rib-like left side gap restricting portion 80AU on the left side surface 80AS, similarly to the left side plate 40D of the image forming units 10 to 13 according to the first embodiment. At the same time, an arcuate gear meshing notch 80AV is formed on the lower surface. On the other hand, the right side plate 80B is lower than the case of the image forming units 10 to 13 in the columnar right side posture regulating projection 80BT similar to the left side plate 40D of the image forming units 10 to 13 according to the first embodiment. It is planted in the central part of the right side 80BS which is the position. Further, the right side plate 80B has a rib-like right side gap restricting portion 80BU similar to the left side plate 40D of the image forming units 10 to 13 according to the first embodiment at a lower side than the case of the image forming units 10 to 13. The right side surface 80BS, which is the position, protrudes toward the lower end of the central rear end portion.

  In addition to this, the unit housing 80 has a left support hole for supporting the shaft at the upper front end of the left side plate 80A, and also on the upper front end of the right side plate 80B facing the left support hole. A right support hole for supporting the shaft is formed. Further, the unit housing 80 is provided with a cylindrical shaft insertion portion connected to the left support hole portion and the right support hole portion at the upper front end portion in the toner recovery portion 80C. Further, in the unit housing 80, a stopper connecting shaft 81 is inserted into the left support hole, the shaft insertion part, and the right support hole. As a result, the unit housing 80 has the left plate 80A and the right plate 80B to make the stopper connecting shaft 81 parallel to the printer left-right direction via the left support hole and the right support hole, and the left end of the shaft and the right end of the shaft. In a state of protruding from the left side surface 80AS and the right side surface 80BS, it is supported to be rotatable in one rotation direction and the other rotation direction. The stopper connecting shaft 81 has a left stopper 82 fixed to the left end of the shaft via a left stopper root, and a substantially lever-shaped right stopper 83 fixed to the right end of the shaft via a right stopper root. ing.

The left stopper 82 is selected so that the left stopper length in the longitudinal direction of the stopper (that is, the length from the left stopper root end to the left stopper tip) is relatively short. The right stopper 83 has, for example, a right stopper length in the longitudinal direction of the stopper (that is, a length from the right stopper root end to the right stopper tip) so that the right stopper center portion can be picked and rotated by a finger. A predetermined length longer than the length of the left stopper is selected. Incidentally, in one aspect, and other aspects of the right stopper 83, recesses relatively shallow arch shape is formed in the right stopper central portion also as such a plurality of ribs are formed at predetermined intervals, accurately with a finger Predetermined processing for picking up and rotating is performed. Thus, the unit housing 80 can rotate the right stopper 83 in one rotation direction or the other rotation direction. When the right stopper 83 is rotated in one rotation direction or the other rotation direction, the unit housing 80 moves the left stopper 82 together with the right stopper 83 via the stopper connecting shaft 81 in the same one rotation direction or the other rotation. Can be rotated in the direction.

  The left side plate 80A of the unit housing 80 has an L-shaped block-shaped protective cover 80AW protruding from the center of the upper end of the left side 80AS near the left stopper 82. As a result, the left side plate 80A protects the left stopper 82 protruding from the left side 80AS from an external impact or the like by the protective cover 80AW. The right stopper 83 is provided with a substantially triangular plate-shaped operation range restricting portion 83A on the right stopper base portion on the other side with the back surface facing the right side surface 80BS. Further, on the back surface of the operation range restricting portion 83A, a rotation restricting piece (not shown) protrudes from a protruding end portion farthest from the right stopper root portion, and engages in the vicinity of a joint portion with the right stopper root portion. A recess (not shown) is provided. Further, on the back surface of the operation range restricting portion 83A, for example, a spring locking portion (not shown) is provided between the rotation restricting piece and the engaging recess. On the other hand, the right side plate 80B of the unit housing 80 is provided with a rotation restricting projection 80BV at a predetermined position on the upper end portion of the right side surface 80BS. Further, the right side plate 80B has an engagement convex portion 80BW (FIG. 17) formed by a U-shaped notch at a predetermined position on the upper front end portion of the right side surface 80BS so that the plate-like root portion has a spring property. Is provided. Further, the right side plate 80B is provided with a spring locking portion 80BX on the front side of the engaging convex portion 80BW on the right side surface 80BS. The stopper connecting shaft 81 is inserted at the right end portion of the shaft into the coil portion of the torsion spring 84, and the coil portion is interposed between the right side surface 80BS and the right stopper root portion of the right stopper 83. In addition, one end of the torsion spring 84 is locked to the spring locking portion of the right stopper 83 and the other end is locked to the spring locking portion 80BX of the right side plate 80B. Thereby, the unit housing 80 biases the right stopper 83 by the torsion spring 84 so as to rotate in the one rotation direction around the stopper connecting shaft 81.

  Therefore, when the unit casing 80 is rotated to the first state in which the right stopper 83 is rotated in one rotation direction and the front end of the right stopper is inclined rearward and downward, the rotation restricting piece is placed on the rotation restricting protrusion 80BV of the right side plate 80B. By abutting, the rotation of the right stopper 83 in one rotation direction is stopped. The unit housing 80 maintains the first state of the right stopper 83 by the urging by the torsion spring 84 and the restriction of the rotation in one rotation direction until the right stopper 83 is rotated in the other rotation direction. . At this time, when the unit casing 80 is rotated to the first state in which the left stopper 82 faces the front side in one rotation direction in conjunction with the rotation of the right stopper 83, the unit housing 80 moves in the one rotation direction of the right stopper 83. As the rotation stops, the rotation of the left stopper 82 in one rotation direction is also stopped. In the unit housing 80, the left stopper 82 is fixed together with the right stopper 83 to the stopper connecting shaft 81. Therefore, the first state of the left stopper 82 is also maintained until the right stopper 83 is rotated in the other rotation direction. maintain. In the first state of the left stopper 82 and the right stopper 83, the left unit support plate 55 and the right unit support plate support the image forming unit 72 at the same mounting position as in the first embodiment described above. It is a state for. Incidentally, the unit housing 80 is not provided with the rotation restricting projection 80BV, the rotation restricting piece, and the torsion spring 84, but the engaging recess and the engaging protrusion on the right side 80BS and the operation range restricting portion 83A of the right stopper 83. And when the right stopper 83 rotates to the first state in one rotation direction, the engagement recess and the engagement projection are engaged with each other, and the first state can be maintained. .

Also as shown in FIGS. 15 and 16, unit case 80, the right stopper 83 is rotated operations to other rotational direction from a first state, when rotated to a second state to direct the right stopper tip beneath almost Then, the engagement convex portion 80BW of the right side plate 80B is engaged with the engagement concave portion, and the rotation of the right stopper 83 in the other rotational direction is stopped. Then, the unit housing 80 maintains the second state of the right stopper 83 by the engagement of the engagement convex portion 80BW with the engagement concave portion until the right stopper 83 is rotated in one rotation direction. At this time, when the unit casing 80 is rotated from the first state to the second state in which the left stopper tip is directed obliquely downward rearward in the other rotation direction in conjunction with the rotation of the right stopper 83, As the rotation of the stopper 83 in the other rotation direction is stopped, the rotation of the left stopper 82 in the other rotation direction is also stopped. Also in this case, the unit housing 80 maintains the second state of the left stopper 82 until the right stopper 83 is rotated in one rotation direction. In the second state of the left stopper 82 and the right stopper 83, the left unit support plate 55 and the right unit support plate support the image forming unit 72 at the same separation position as in the first embodiment. It is a state for.

  On the other hand, as shown in FIGS. 17 and 18 in which the same reference numerals are assigned to the corresponding parts as in FIGS. 6 and 7, the right unit support plate 86 has a substantially flat surface 86A as an engaging portion at the upper end. A plate-like right-hand overhanging portion 86B that projects outward is provided. Further, as described above, the right stopper length is longer than the left stopper length. For this reason, the right unit support plate 86 has a height from the lower end to the right overhanging portion 86B according to the right stopper length, so that the right unit support plate 86 is protruded from the lower end of the right unit support plate 56 according to the first embodiment. A predetermined height lower than the height up to the portion 56B is selected. The right unit support plate 86 has one surface 86A in the printer housing 2 substantially parallel to the one surface 55A of the left unit support plate 55 at a predetermined interval, and the right projecting portion 86B on the left side of the left unit support plate 55. It arrange | positions and is located below the overhang | projection part 55B. Incidentally, the right unit support plate 86 has a lower end portion formed in the same manner as the lower end portion of the right unit support plate 56 according to the first embodiment, and like the right unit support plate 56 according to the first embodiment, The transfer unit 18 is supported together with the left unit support plate 55.

  Further, on one surface 86A of the right unit support plate 86, the image forming units 72 to 72 with respect to the printer casing 2 are disposed at positions opposed to the four left guide portions 55C via the right ends of the drum shafts 20A of the photosensitive drums 20 to 23. Four right guide portions 86C for guiding the mounting of 75 are formed. The four right guide portions 86C are each formed as a substantially U-shaped notch on one surface 86A of the right unit support plate 86, and the width of the central portion is selected to be a predetermined width wider than the diameter of the drum shaft 20A. At the same time, the width of the shaft support end is selected to be a predetermined width substantially equal to the diameter of the drum shaft 20A. In addition, each of the four right guide portions 86C has a width at the upper end portion that gradually increases from the center portion to the right overhang portion 86B. However, the right side guide restricting projections 80BT of the corresponding image forming units 72 to 75 have the same width. A predetermined width wider than the width of the upper end portion of the right guide portion 56C of the right unit support plate 56 according to the first embodiment is selected so as to be engageable. As a result, the four right guide portions 86C each have an upper end that is a guide open end that allows the right end portion of the drum shaft 20A and the right posture restricting projection 80BT to be sequentially inserted from the upper side and to be sequentially pulled upward. That is, the four right guide portions 86C have both a mounting guide function for guiding the mounting of the image forming units 72 to 75 and a mounting posture regulating function for regulating the mounting posture.

  Therefore, when the image forming unit 72 is mounted, the printer housing 2 rotates the right stopper 83 in one rotation direction in the image forming unit 72 to set the left stopper 82 together with the right stopper 83 to the first state. The printer housing 2 brings the image forming unit 72 close to the left unit support plate 55 and the right unit support plate 86 from the upper side in the same posture as in the first embodiment, and the left end portion and the right end portion of the drum shaft 20A. The part is inserted into the left guide part 55C and the right guide part 86C from the guide open end. In addition, when the image forming unit 72 is inserted between the left unit support plate 55 and the right unit support plate 86, the printer housing 2 has a left end portion and a right end portion of the drum shaft 20A in the left guide portion 55C and the right guide portion 86C. Is moved to the shaft support end. At this time, when the image forming unit 72 is inserted to some extent between the left unit support plate 55 and the right unit support plate 86, the printer housing 2 moves the left posture restriction projection 80AT from the engagement portion open end to the left engagement portion. The right posture regulating protrusion 80BT is inserted into the right guide portion 86C from the guide open end. Then, when the image forming unit 72 is further pushed between the left unit support plate 55 and the right unit support plate 86, the printer housing 2 moves the left stopper 82 and the right stopper 83 to the left projecting portion 55B and the right projecting portion 56B. The bottom of the fitting groove 20AX of the drum shaft 20A is abutted against the guide tip of the left guide portion 55C without being brought into contact with the shaft support end portion, and the right end portion of the drum shaft 20A is fitted to the right guide portion. It abuts against the guide tip of the part 86C.

  As a result, the printer housing 2 supports the drum shaft 20A substantially parallel to the left-right direction of the printer at the shaft support end portions of the left guide portion 55C and the right guide portion 86C. In addition, the printer housing 2 is engaged with the left posture restriction protrusion 80AT by inserting the left posture restriction protrusion 80AT into the protrusion engagement end portion of the left engagement portion 55D, and the right posture restriction protrusion 80BT on the front edge of the upper end portion of the right guide portion 86C. Engage with contact. As a result, the printer housing 2 is rotated in the direction of one rotation around the drum shaft 20A with respect to the image forming unit 72 via the left posture restriction protrusion 80AT and the right posture restriction protrusion 80BT by the left engagement portion 55D and the right guide portion 86C. Further, it prevents the body from falling down so as to rotate in the other rotation direction, and maintains an almost upright posture. In this way, when both the left stopper 82 and the right stopper 83 of the image forming unit 72 are set to the first state, the printer housing 2 is positioned at the mounting position between the left unit support plate 55 and the right unit support plate 86. 72, the surface of the photosensitive drum 20 can be brought into contact with the surface of the transfer belt 27, and the drive gear 57 can be engaged with the drum gear 58 by entering the gear engagement notch 80AV. Incidentally, when the image forming unit 72 is detached, the printer housing 2 is pulled out so as to lift the image forming unit 72 from between the left unit support plate 55 and the right unit support plate 86, so It can be easily removed by the reverse procedure.

  On the other hand, in the second state, the left stopper 82 has the left stopper tip directed rearward and obliquely downward, and at that time, the portion of the left stopper tip that faces substantially directly below forms an obtuse angle with one side facing the front side. It is formed so as to be a substantially horizontal left stopper tip surface that intersects. The left stopper 82 is formed such that a boundary portion between one side surface and the left stopper front end surface is a curved surface (hereinafter also referred to as a left stopper curved surface). In the second state, the right stopper 83 is formed so that the tip of the right stopper is almost directly below, and the portion of the right stopper tip that is substantially directly below is the substantially horizontal right stopper tip. Yes. The right stopper 83 is also formed so that a boundary portion between one side surface facing the front side and the right stopper tip surface is a curved surface (hereinafter also referred to as a right stopper curved surface). In addition, the length of the left stopper 82 from the stopper connecting shaft 81 to the front end surface of the left stopper along the vertical direction in the second state is the vertical direction when the image forming unit 72 is mounted at the mounting position. A predetermined length longer than the distance from the stopper connecting shaft 81 along the upper surface of the left overhang 55B is selected. The right stopper 83 has a length from the stopper connecting shaft 81 to the right stopper tip surface along the vertical direction in the second state, and the length along the vertical direction when the image forming unit 72 is mounted at the mounting position. The predetermined length is selected to be longer than the distance from the connecting shaft 81 to the upper surface of the right overhanging portion 86B.

  Accordingly, as shown in FIGS. 19 and 20 in which the same reference numerals are given to corresponding parts to FIGS. 9 and 10, the printer housing 2 has the right stopper 83 in a state where the image forming unit 72 is mounted at the mounting position. When the rotation operation is performed in the other rotation direction, both the right stopper 83 and the left stopper 82 are rotated in the other rotation direction from the first state accordingly. At this time, the printer housing 2 abuts the right stopper curved surface against the upper surface of the right overhanging portion 86B of the right unit support plate 86 in accordance with the rotation of the right stopper 83 in the other rotation direction, and then the right stopper 83 Slide from the curved surface to the tip of the right stopper. When the right stopper 83 is rotated to the second state in the other rotation direction, the printer housing 2 is rotated in the other direction by inserting the right stopper 83 between the right end portion of the stopper connecting shaft 81 and the right extension portion 86B. The rotation in the direction is stopped, and the entire front end surface of the right stopper is pressed and engaged with the upper surface of the right overhanging portion 86B. In addition, the printer housing 2 abuts the left stopper curved surface against the upper surface of the left overhanging portion 55B according to the rotation of the left stopper 82 in the other rotation direction, and then extends from the left stopper curved surface to the left stopper leading end surface. Slide in order. Then, when the left stopper 82 rotates to the second state in the other rotation direction, the printer casing 2 causes the left stopper 82 to enter between the left end portion of the stopper connecting shaft 81 and the left overhang portion 55B, and the right stopper. 83, the rotation in the other rotation direction is stopped, and the entire front end surface of the left stopper is pressed and engaged with the upper surface of the left overhanging portion 55B. Thus, the printer housing 2 is moved from the mounting position of the image forming unit 72 between the left unit support plate 55 and the right unit support plate 86 to the separated position on the unit pull-out side by the left stopper 82 and the right stopper 83 in the second state. Can be lifted. Therefore, the printer housing 2 can be separated from the surface of the transfer belt 27 in the image forming unit 72 by the predetermined first distance D1 while the surface of the photosensitive drum 20 is substantially parallel, and the drum gear 58 is separated from the drive gear 57. Can be separated.

  Here, in the printer housing 2, when the image forming unit 72 is mounted, the drum shaft 20A follows the shape of the left guide portion 55C and the right guide portion 86C between the left unit support plate 55 and the right unit support plate 86. By following the movement path at the time of mounting from the guide open end to the guide front end, the image forming unit 72 is displaced from the upper side to the rear obliquely lower side, which becomes the unit insertion side. That is, when the printer housing 2 is disassembled into two parts in the horizontal direction and the vertical direction when the image forming unit 72 is mounted, the image forming unit 72 forms the image formation between the left unit support plate 55 and the right unit support plate 86. The unit 72 is displaced downward in the horizontal direction while being displaced downward in the vertical direction. For this reason, when the printer housing 2 is separated from the mounting position of the image forming unit 72, the right stopper leading end and the left stopper leading end are both near the right protruding portion 86B and the left protruding portion 55B. The right stopper 83 and the left stopper 82 are rotated in the other rotation direction so as to be displaced to the front side opposite to the direction of displacement in the horizontal direction at the time of mounting (that is, the rear side). In the printer housing 2, the lengths from the stopper connecting shaft 81 to the right stopper front end surface and the left stopper front end surface in the right stopper 83 and the left stopper 82 are appropriately selected.

  Accordingly, when the printer housing 2 is separated from the mounting position of the image forming unit 72, the left unit support plate 55 and the left stopper 83 and the left stopper 82 are rotated by rotating the right stopper 83 and the left stopper 82 from the first state to the second state in the other rotation direction. The image forming unit 72 is moved to the lower side so that the movement path along the shape of the left guide portion 55C and the right guide portion 86C can be traced in reverse between the right unit support plate 86 without being caught by the drum shaft 20A. It is possible to displace the front diagonally upper side from the unit pulling side. At this time, the printer housing 2 slides the right posture regulating protrusion 80BT upward with respect to the front edge of the upper end portion of the right guide portion 86C according to the rotation of the right stopper 83 and the left stopper 82 in the other rotational direction. In addition, the image forming unit 72 can be regulated in the same manner as when the image forming unit 72 is mounted by sliding the left attitude regulating projection 80AT upward with respect to the front edge of the projection engaging end of the left engaging portion 55D. it can. Accordingly, when the printer housing 2 rotates the right stopper 83 and the left stopper 82 to the second state in response to the rotation operation in the other rotation direction with respect to the right stopper 83, the left unit support plate 55 and the right unit support plate The image forming unit 72 can be smoothly lifted to the separation position between the positions 86 while maintaining the posture almost upright from the mounting position (that is, with the upper surface of the unit housing 80 being substantially horizontal).

  By the way, when the image forming unit 72 is mounted, the printer housing 2 fits the fitting groove 20AX of the drum shaft 20A to the shaft support end of the left guide portion 55C, thereby supporting the left unit support plate 55 and the right unit support. The image forming unit 72 is positioned and mounted between the plates 86 so that the unit center position substantially coincides with the center position between the support plates. In the printer housing 2, in order to position and mount the image forming unit 72 with high accuracy, the width of the fitting groove 20AX of the drum shaft 20A is set to a plate where the left guide portion 55C is formed on the left unit support plate 55. It is appropriately selected so as to be as close as possible to the thickness. For this reason, in the image forming unit 72, the mounting angle of the left stopper 82 is appropriately selected based on the mounting angle of the right stopper 83 with respect to the stopper connecting shaft 81. Thus, when the printer housing 2 is separated from the mounting position of the image forming unit 72, the left stopper 82 is moved together with the right stopper 83 from the first state to the other rotation direction in response to the rotation operation of the right stopper 83 in the other rotation direction. The left stopper curved surface of the left stopper 82 on the left overhanging portion 55B at a timing slightly earlier than the timing at which the right stopper curved surface of the right stopper 83 abuts against the right overhanging portion 86B and starts sliding. They are starting to slide against each other. Therefore, the printer housing 2 moves the left side unit support plate 55 and the right unit support plate 86 between the left unit support plate 55 and the right unit support plate 86 on the left side slightly faster than the right side by rotating in the other rotation direction. Lifting. That is, the printer housing 2 starts to move the fitting groove 20AX of the drum shaft 20A in the shaft support end portion of the left guide portion 55C, and then moves the right end portion of the drum shaft 20A in the guide tip of the right guide portion 86C. The image forming unit 72 is lifted from the mounting position so as to start moving. As a result, when the printer housing 2 is separated from the mounting position of the image forming unit 72, the right side of the image forming unit 72 is lifted faster than the left side, so that the drum shaft 20A is fitted to the shaft support end of the left guide portion 55C. The joint groove 20AX is caught and caught to prevent the image forming unit 72 from being lifted smoothly from the mounting position.

  Further, when the image forming unit 72 is lifted to the separated position, the printer housing 2 is configured such that the image forming unit 72 is constituted by the right posture restricting protrusion 80BT and the left posture restricting protrusion 80AT, the right guide portion 86C, and the left engaging portion 55D. It is prevented from falling down so as to rotate in one rotation direction around the drum shaft 20A. In addition, when the image forming unit 72 is lifted to the separated position, the printer housing 2 has the right stopper 83 in the second state so that the longitudinal direction of the stopper is substantially parallel to the vertical direction of the printer and the right end of the shaft The entire front end surface of the right stopper is pressed against the upper surface of the right side overhanging portion 86B just below the portion. The right stopper 83 is formed so that the rear end portion of the right stopper front end surface protrudes from a position directly below the right end of the shaft to the rear side from the other side facing the rear side, and the right stopper front end surface has a certain size. Has been. In addition, when the image forming unit 72 is lifted to the separated position, the printer housing 2 is tilted so that the longitudinal direction of the stopper is lowered with respect to the longitudinal direction of the printer by setting the left stopper 82 in the second state. Thus, the entire front end surface of the left stopper is pressed against the upper surface of the left overhanging portion 55B on the diagonally lower rear side of the left end portion of the shaft. As a result, when the image forming unit 72 is lifted to the separated position, the printer housing 2 causes the right stopper 83 and the left stopper 82 to function as the posture restricting portions, respectively, so that the right stopper 83 and the left stopper 82 The portion 86B and the left overhang portion 55B prevent the image forming unit 72 from falling down so as to rotate in the other rotation direction around the drum shaft 20A. In this way, the printer housing 2 can maintain the substantially upright posture by preventing the image forming unit 72 lifted to the separated position from falling to either the front side or the rear side.

  Even when the image forming unit 72 is lifted from the mounting position to the separation position in this manner, the right and left stoppers 83 and 82 are moved according to the rotation of the right stopper 83. Is rotated in one rotation direction from the second state. At this time, the printer housing 2 slides the right stopper curved surface in order from the right stopper tip surface to the upper surface of the right overhanging portion 86B according to the rotation of the right stopper 83 in one rotation direction. The right stopper curved surface is pulled away from the protruding portion 86B. Then, when the right stopper 83 rotates to the first state in one rotation direction, the printer housing 2 stops the rotation in the one rotation direction. Further, the printer housing 2 sequentially slides the left stopper curved surface from the front end surface of the left stopper with respect to the upper surface of the left overhanging portion 55B according to the rotation of the left stopper 82 in the other rotation direction. Pull the left stopper curved surface away from 55B. When the left stopper 82 rotates to the first state in one rotation direction, the printer housing 2 stops rotating in the one rotation direction together with the right stopper 83. As a result, the printer housing 2 can be mounted again by dropping the image forming unit 72 from the separation position to the mounting position between the left unit support plate 55 and the right unit support plate 86. Therefore, the printer housing 2 can be brought into contact with the surface of the transfer belt 27 in the image forming unit 72 while keeping the surface of the photosensitive drum 20 substantially parallel, and the drum gear 58 can be engaged with the drive gear 57.

  By the way, once the image forming unit 72 is mounted between the left unit support plate 55 and the right unit support plate 86 in the printer housing 2, the image is thereafter displayed between the left unit support plate 55 and the right unit support plate 86. The image forming unit 72 can be lifted from the mounting position to the separation position and can be lowered from the separation position to the mounting position simply by rotating the right stopper 83 without having to hold the formation unit 72 by hand to lift or remove it. It can be attached again. Accordingly, as shown in FIG. 21, the printer housing 2 is opened to the upper right (for example, via a hinge (not shown) in which the opening / closing cover 2B is provided in the housing main body 2A across the left edges). If the right and left edges are separated from each other and brought into contact with each other), the opening / closing cover 2B can be inserted into the printer housing 2 with respect to the housing main body 2A, or a few fingers can be inserted. The right stopper 83 can be easily rotated by simply opening it slightly.

  In the case of the second embodiment, the image forming unit 72 rotates the right stopper 83 and the left stopper 82 from the first state to the second state in the other rotation direction, and reversely. For this purpose, a stopper connecting shaft 81 is provided at the upper front end of the unit housing 80, and a left stopper 82 and a right stopper 83 are fixed thereto. Thus, the image forming unit 72 sets the right stopper 83 and the left stopper 82 within the upper end of the right side 80BS and the upper end of the left side 80AS even if the right stopper 83 is rotated in one rotation direction or the other rotation direction. It can be rotated to the 1st state of a rotation direction, and the 2nd state of another rotation direction. That is, the image forming unit 72 is configured so that the right stopper 83 and the left stopper 82 do not protrude outside the right side surface 80BS and the left side surface 80AS even when the right stopper 83 is rotated in one rotation direction or the other rotation direction. ing. Therefore, although the printer housing 2 is different from the first embodiment described above in the mounting mechanism of the image forming units 72 to 75, the four image forming units 72 to 75 are the same as those in the first embodiment described above. As in the case of, it can be arranged at a desired interval.

(2-3) Operation and Effect of Second Embodiment In the above configuration, the color printer 70 includes the left stopper 82 and the rotation operation via the stopper connecting shaft 81 in each of the four image forming units 72 to 75. by both rotating the right stopper 83, possible as Ru provided so as to be switched to a first state and a second state. In the color printer 70, a pair of left unit support plate 55 and right unit support plate 86 are disposed in the printer housing 2 with their one surfaces 55A and 86A facing each other, and the left unit support plate 55 and right unit support are supported. The left overhang 55B and the right overhang 86B are provided at the upper end of the plate 86. Then, the color printer 70 sets the right stopper 83 and the left stopper 82 in the first state in response to the rotation operation in the one rotation direction with respect to the right stopper 83, and the image forming units 72 to 75 support the left unit support plate 55 and the right unit support. When inserted between the plates 86, the image forming units 72 to 75 are attached to the attachment positions without engaging the right stopper 83 and the left stopper 82 with the right extension part 86B and the left extension part 55B, The surfaces of the photosensitive drums 20 to 23 are brought into contact with the surface of the transfer belt 27. In addition, when the right stopper 83 is rotated in the other rotation direction, the color printer 70 rotates the right stopper 83 and the left stopper 82 to the second state in the other rotation direction accordingly, Engage with the left overhang 55B. As a result, the color printer 70 lifts the image forming units 72 to 75 from the mounting position to the separation position between the left unit support plate 55 and the right unit support plate 86 to separate the photosensitive drums 20 to 23 from the transfer belt 27.

  According to the above configuration, the color printer 70 can obtain the same effect as that obtained by the first embodiment described above, and in addition to this, the left unit support plate 55 and the right unit support plate 86. After mounting the image forming units 72 to 75 at the mounting position between them, the right stopper 83 can be rotated and operated without having to hold the image forming units 72 to 75 by hand and lift or remove them. The image forming units 72 to 75 can be lifted from the mounting position to the separated position and mounted again to the mounting position. Therefore, the color printer 70 performs an operation for lifting the image forming units 72 to 75 from the mounting position to the separation position between the left unit support plate 55 and the right unit support plate 86 and remounting the image forming units 72 to 75 from the separation position to the mounting position. Compared to the first embodiment described above, it can be greatly simplified.

  Further, the color printer 70 is provided with a left stopper 82 and a right stopper 83 via stopper connecting shafts 81 in the four image forming units 72 to 75, respectively, and a mounting position between the left unit support plate 55 and the right unit support plate 86. After the image forming units 72 to 75 are mounted, when the right stopper 83 is rotated, both the right stopper 83 and the left stopper 82 are switched from the first state to the second state accordingly. As a result, the color printer 70 lifts the image forming units 72 to 75 to the separated position between the left unit support plate 55 and the right unit support plate 86 without tilting left and right from the mounting position by the right stopper 83 and the left stopper 82. Can do. Therefore, as in the first embodiment described above, the color printer 70 does not need to particularly control the gaps between the left unit support plate 55 and the right unit support plate 86 and the image forming units 72 to 75. When 72 to 75 are lifted from the mounting position to the separation position, the surfaces of the photosensitive drums 20 to 23 can be separated from the surface of the transfer belt 27 while being substantially parallel to each other. At this time, the color printer 70 can accurately separate the drum gear 58 from the drive gear 57 in the image forming units 72 to 75. The color printer 70 can displace the image forming units 72 to 75 without particularly controlling the gaps between the left unit support plate 55 and the right unit support plate 86 and the image forming units 72 to 75. The degree of design freedom of 70 can be improved.

  Further, when the color printer 70 is separated from the mounting position of the image forming units 72 to 75, the right stopper 83 and the left stopper 82 are moved from the first state to the unit insertion side when the image forming units 72 to 75 are mounted. It was made to rotate to the 2nd state of the other rotation direction used as the other side. As a result, when the color printer 70 is separated from the mounting positions of the image forming units 72 to 75, the rotation of the right stopper 83 and the left stopper 82 in the other rotation direction causes the space between the left unit support plate 55 and the right unit support plate 86. Thus, the image forming unit 72 can be smoothly lifted from the mounting position to the separated position by reversing the moving path during mounting without being caught by the drum shaft 20A. In addition, the color printer 70 appropriately selects the mounting angle of the left stopper 82 based on the mounting angle of the right stopper 83 with respect to the stopper connecting shaft 81 in the image forming units 72 to 75, and the right stopper 83 and the left stopper 82 are When both are rotated in the other rotation direction, the left stopper 82 located on the side where the fitting groove 20AX of the drum shaft 20A is formed is abutted against the left overhanging portion 55B, and then the right stopper 83 is brought into contact with the right overhanging portion 86B. I tried to hit it. Therefore, the color printer 70 prevents the fitting groove 20AX of the drum shaft 20A from being caught by the shaft support end portion of the left guide portion 55C and is caught, thereby separating the image forming units 72 to 75 more smoothly from the mounting position. Can be lifted into position.

  Further, in the color printer 70, one of the left stopper 82 and the right stopper 83 provided in each of the four image forming units 72 to 75 has a relatively short left stopper length, and the right stopper 83 has a right stopper. The stopper length is longer than the left stopper length. Thereby, the color printer 70 can intuitively recognize that the rotation stopper is the right stopper 83 among the left stopper 82 and the right stopper 83 due to the difference between the left stopper length and the right stopper length. . In addition, the color printer 70 performs predetermined processing for the right stopper 83 to be accurately picked and rotated by a finger. Accordingly, the color printer 70 can more reliably recognize that the rotation stopper among the left stopper 82 and the right stopper 83 is the right stopper 83.

(3) Other embodiments (3-1) Other embodiments 1
In the first embodiment described above, the stopper 60 is turned on the right side surface 40EA of the unit housing 40 of the four image forming units 10 to 13 so as to be switched between the first state and the second state. The case of providing was described. However, the present invention is not limited to this. For example, as shown in FIGS. 22A and 22B, a prismatic base 102 is provided on the right side surface 101A of the unit housing 101 of the image forming unit 100 in the vertical direction of the printer. In a first state in which a substantially U-shaped stopper 103 is rotated around a shaft 104 parallel to the front-rear direction of the printer and folded, and a second state in which the stopper is expanded at an angle of 90 degrees. You may provide so that switching is possible. In the present invention, when the image forming unit 100 is inserted between the left unit support plate 55 and the right unit support plate 56 with the stopper 103 in the first state, the stopper 103 is inserted into the right guide portion 56C. an image forming unit 100 is mounted to the mounting position, if the image forming unit 100 by the stopper 103 to the second state is inserted between the left side unit support plate 55 and the right unit supporting plate 56, the stopper 103 right Zhang The image forming unit 100 may be attached to the separated position by abutting and engaging with the protruding portion 56B.

  In the present invention, for example, as shown in FIG. 23A, a block-shaped engagement portion 112 is provided on the right side surface 111A of the unit casing 111 of the image forming unit 110, and the right side support plate 113 is extended to the right side. A substantially L-shaped stopper 114 is pivoted around the shaft 115 parallel to the up-down direction of the printer in the first portion where the entire portion is retracted from the right guide portion 113B, and one end portion is the right guide portion. You may provide so that it can switch to the 2nd state to which it protrudes on 113B. Further, in the present invention, as shown in FIG. 23 (B), a substantially square plate-like stopper 116 is slid in the left-right direction of the printer on the right-side protruding portion 113A of the right-side unit support plate 113 in place of the stopper 114. You may provide so that it can switch to the 1st state which retreats the whole from the right side guide part 113B, and the 2nd state which pushes one end part on the right side guide part 113B. In the present invention, when the image forming unit 110 is inserted between the left unit support plate 55 and the right unit support plate 113 with the stoppers 114 and 116 in the first state, the engaging portion 112 is moved to the right guide portion 113B. When the image forming unit 110 is inserted into the mounting position, the stoppers 114 and 116 are set in the second state, and the image forming unit 110 is inserted between the left unit support plate 55 and the right unit support plate 113, The image forming unit 110 may be attached to the separated position by engaging the engaging portion 112 with one end of the stoppers 114 and 116 from above.

  Furthermore, in the present invention, for example, as shown in FIGS. 24A and 24B, a substantially L-shaped engagement portion 122 is provided on the right side surface 121A of the unit casing 121 of the image forming unit 120, and the concave portion thereof is provided. In addition to being provided toward the unit insertion side, a substantially L-shaped block stopper 124 is rotated around a shaft (not shown) parallel to the horizontal direction of the printer near the right guide portion 123A on the right unit support plate 123. In addition, the first state in which the entirety is retracted from the right guide portion 123A and the second state in which one end portion enters the right guide portion 123A and the concave portion faces the unit pulling side may be provided. In the present invention, when the stopper 124 is in the first state and the image forming unit 120 is inserted between the left unit support plate 55 and the right unit support plate 123, the engaging portion 122 is inserted into the right guide portion 123A. When the image forming unit 120 is mounted at the mounting position and the stopper 124 is in the second state and the image forming unit 120 is inserted between the left unit support plate 55 and the right unit support plate 123, one end of the stopper 124 is inserted. The image forming unit 120 may be attached to the separation position by engaging the engaging portion 122 with the portion from above.

Further, the present invention replaces the right side surfaces 40EA, 101A, 111A, 121A and the right side unit support plates 56, 113, 123 of the image forming units 10 to 13, 100, 110, 120 with the image forming units 10 to 13, 100. , 110, 120 are provided with stoppers 60, 103, 114, 116, 124 on one of the left side surface 40DA and the left unit support plate 55, and on the other side, an engaging portion such as the left side overhanging portion 55B, or the block described above. The engagement portions 112 and 122 may be provided. Furthermore, according to the present invention, the states of the stoppers 60, 103, 114, 116, and 124 may be manually switched (ie, rotated) to the first state and the second state. The stoppers 114, 116, and 124 provided on the unit support plates 113 and 123 can be switched between the first state and the second state according to the driving of the stopper driving motor. In particular, the present invention applies the configuration described above with reference to FIGS. 24A and 24B to the right side surface 121A or the left side surface of the image forming unit 120 and the right unit support plate 123 or the left unit support plate 55, thereby driving the stopper. When the state of the stopper 124 is switched in accordance with the driving of the motor, the stopper 124 can be automatically operated from the state where the image forming unit 120 is mounted at the mounting position to be displaced to the separated position. The present invention can achieve the same effects as those of the first embodiment described above even by the various configurations described above. By the way, in the present invention, when the image forming units 10 to 13 and 100 are provided with the stoppers 60 and 103 and the state is switched manually, for example, in the printer housing 2, the opening / closing cover 2B is opened with respect to the housing body 2A. It will be. According to the present invention, the image forming units 10 to 13 and 100 attached to the separation position at this time protrude from the image forming units 10 to 13 and 100 attached to the attachment position to the unit extraction side. It is possible to intuitively recognize whether the image forming units 10 to 13 and 100 are attached at the attachment position or at the separation position. However, according to the present invention, the stoppers 60 and 103 are provided so as to protrude from the unit housings 40 and 101 of the image forming units 10 to 13 and 100 so that they can be easily seen. Also depending on the state, it is possible to intuitively recognize whether the corresponding image forming units 10 to 13 and 100 are attached at the attachment position or at the separation position. For this reason, the present invention, for example, by coloring the stoppers 60 and 103 of the image forming units 10 to 13 and 100 into colors indicating the toners stored in the image forming units 10 to 13 and 100, respectively. According to the colors 60 and 103, it is possible to intuitively recognize which image forming unit 10 to 13, 100 containing the toner of the color is attached at the attachment position or at the separation position. It is possible to prevent the image forming units 10 to 13 and 100 from being erroneously attached to the attachment position and attached to the separation position.

(3-2) Other Embodiment 2
In the first embodiment described above, the gap S1 between the one surface 55A of the left unit support plate 55 and the surface of the left side restricting portion is restricted by the left side gap restricting portion 40DC, and the image forming units 10 to 13 are attached to the separated positions. When tilted, the image forming units 10 to 13 are engaged with the engagement position of the stopper 60 with respect to the right-side protruding portion 56B and the engagement of the engagement groove 20AX of the drum shaft 20A with the shaft support end portion of the left-side guide portion 55C. The case where the position is supported at three places, that is, the contact position of the surface of the left regulating portion with respect to one surface 55A of the left unit support plate 55 has been described. However, the present invention is not limited to this, and the right gap regulating portion 40EC regulates the gap between the one surface 56A of the right unit support plate 56 and the surface of the right regulating portion in the same manner as the left gap S1. In the case where the image forming unit 10 is tilted when attached to the separated position, the lower edge of the surface of the right restricting portion is abutted against one surface 56A of the right unit support plate 56, so that the image forming units 10 to 13 are at least on the right extending portion. 56B is supported at three positions: the engagement position of the stopper 60 with respect to 56B, the contact position of the left regulation surface with respect to one surface 55A of the left unit support plate 55, and the contact position of the right regulation portion surface with respect to one surface 56A of the right unit support plate 56. You may do it. That is, according to the present invention, the shaft support end portion of the left guide portion 55C is fitted to the fitting groove 20AX of the drum shaft 20A when the image forming units 10 to 13 are attached to the attachment position. However, even when the image forming units 10 to 13 are mounted at the separated positions, the image forming units 10 to 13 are removed from the transfer belt 27 even if they are formed so as not to be fitted to the fitting grooves 20AX of the drum shaft 20A. The photosensitive drums 20 to 23 can be supported in a separated state. In the present invention, for example, when the stopper 60 is in the second state, the other end portion of the other side surface of the stopper 60 that engages with the right side protruding portion 56B, and the stopper 60 at the right side protruding portion 56B. A rubber sheet having a relatively high friction coefficient may be attached to at least one of the joint positions. According to the present invention, the gap between the left side surface 40DA and the right side surface 40EA of the image forming units 10 to 13 and the one surface 55A of the left unit support plate 55 and the one surface 56A of the right unit support plate 56 is specifically regulated. Even when the image forming units 10 to 13 are attached to the separation positions, the inclination of the image forming units 10 to 13 can be remarkably reduced to separate the entire surface of the photosensitive drums 20 to 23 from the surface of the transfer belt 27.

(3-3) Other Embodiment 3
Further, in the above-described second embodiment, the case where both the right stopper 83 and the left stopper 82 are rotatably provided in the image forming units 72 to 75 via the stopper connecting shaft 81 has been described. However, the present invention is not limited to this. The left stopper 82 is not provided in the image forming units 72 to 75, and a substantially lever-like stopper having the same configuration as the right stopper 83 is provided only on one of the right side surface 80BS and the left side surface 80AS. Or you may provide rotatably in both. In the present invention, when the left stopper 82 is not provided in the image forming units 72 to 75 and a substantially lever-like stopper having the same configuration as the right stopper 83 is provided only on one of the right side surface 80BS and the left side surface 80AS, the first described above. As in the case of this embodiment, by controlling the gaps between the left unit support plate 55 and the right unit support plate 86 and the image forming units 72 to 75, the image forming unit 72 is controlled according to the rotation operation with respect to the stopper. Or 75 can be lifted from the mounting position to the separation position and lowered from the separation position to the mounting position to be mounted again. On the other hand, according to the present invention, the left stopper 82 is not provided in the image forming units 72 to 75, and a substantially lever-like stopper having the same configuration as the right stopper 83 is rotatably provided on both the right side surface 80BS and the left side surface 80AS. In this case, for example, by configuring the left unit support plate 55 in the same manner as the right unit support plate 86, the image forming units 72 to 75 are moved from the mounting position to the separated position regardless of which of the right and left stoppers is rotated. It can be lifted and lowered from the remote position to the mounting position and mounted again. According to the present invention, the usability of the color printer 70 can be improved. Further, according to the present invention, for example, even if the opening / closing cover 2B is attached to the housing body 2A so that it can be opened / closed by upper right opening, upper left opening, front upper opening, and rear upper opening, the stopper can be rotated. The degree of freedom in designing the color printer 70 can be improved. By the way, in the present invention, in the configuration of the second embodiment and the various configurations of the stopper that can be rotated as described above, as in the case described in the other embodiments 1, the housing main body 2A is provided. On the other hand, when the open / close cover 2B is opened, the image forming units 72 to 75 are mounted depending on whether the image forming units 72 to 75 protrude to the unit pulling side and the state of the right stopper 83 or the rotatable stopper. It can be intuitively recognized whether it is mounted in a position or lifted to a remote position. In the present invention, the right stopper 83 and the rotatable stopper of the image forming units 72 to 75 are colored with the color indicating the toner contained in the image forming units 72 to 75, respectively. It is possible to intuitively recognize whether the image forming units 72 to 75 containing toner are mounted at the mounting position or lifted to the separation position, and the image forming units 72 to 75 are erroneously attached to the mounting position. And can be prevented from being lifted to a remote position.

(3-4) Other Embodiment 4
Further, in the first and second embodiments described above, the case where the image forming apparatus according to the present invention is applied to the color printers 1 and 70 of the primary transfer system described above with reference to FIGS. However, the present invention is not limited to this, and is a secondary transfer system in which the toner image on the surface of the photosensitive drum is transferred to the surface of the intermediate transfer belt, and then the toner image on the surface of the intermediate transfer belt is transferred to the surface of the printing medium. The present invention can be applied to a color printer or a monochrome electrophotographic printer (hereinafter also referred to as a monochrome printer). For example, as shown in FIG. 25 in which parts corresponding to those in FIG. 1 are given the same reference numerals, a secondary transfer type color printer 130 is provided with a secondary transfer type transfer unit 132 in an image forming unit 131. In the transfer unit 132, an endless intermediate transfer belt 134 is stretched between a belt driving roller 25, a driven roller 26, and a backup roller 133 that are provided so as to be rotatable in one rotation direction. The photosensitive drums 20 to 23 are brought into contact with each other. The transfer unit 132 has four primary transfer rollers 135 to 138 arranged at positions facing the four photosensitive drums 20 to 23, and these primary transfer rollers 135 to 138 are in contact with the back surface of the intermediate transfer belt 134. I am letting. Further, in the transfer unit 132, a secondary transfer roller 139 is provided at a position facing the backup roller 133 so as to be rotatable in the other rotation direction, and the secondary transfer roller 139 is brought into contact with the surface of the intermediate transfer belt 134. Note that the secondary transfer type color printer 130 shown in FIG. 25 includes the photosensitive drums 20 to 23 and other various rollers in the image forming units 10 to 13 and 72 to 75 as in the above-described embodiment. Rotate in the opposite direction. As a result, the color printer 130 transfers the toner images on the surfaces of the four photosensitive drums 20 to 23 in the transfer unit 132 so as to sequentially overlap the surfaces of the intermediate transfer belt 134 via the four primary transfer rollers 135 to 138. After that, the toner images for the four colors on the surface of the intermediate transfer belt 134 can be transferred to the surface of the printing medium 5 while the printing medium 5 is conveyed by the secondary transfer roller 139 together with the intermediate transfer belt 134. In the present invention, when the image forming apparatus is applied to the color printer 130, the surfaces of the photosensitive drums 20 to 23 are brought into contact with or separated from the surface of the intermediate transfer belt 134. The present invention also provides an image forming apparatus, a monochrome printer to which only one image forming unit is detachably mounted, a color printer to which at least five image forming units are detachably mounted, and a transfer belt. Color printer or monochrome printer, MFP (Multi-Function Peripheral) that transfers the toner image on the surface of the photosensitive drum to the printing medium while conveying the printing medium by the photosensitive drum and the transfer roller without providing an intermediate transfer belt In addition, the present invention can be widely applied to image forming apparatuses having various other configurations such as facsimile machines, multifunction machines, and copiers.

(3-5) Other Embodiment 5
Furthermore, in the first and second embodiments described above, FIGS. 1 to 25 are described as stoppers provided on one side of the image forming unit so as to be switchable between the first state and the second state. The case where the stoppers 60 and 103 and the right stopper 83 provided on the right side surfaces 40EA, 80BS, and 101A of the image forming units 10 to 13, 72 to 75, and 100 are applied has been described. However, the present invention is not limited to this, and stoppers having the same configuration as the stoppers 60 and 103 and the right stopper 83 provided on the left side surfaces 40DA and 80AS of the image forming units 10 to 13, 72 to 75, 100, and various shapes and sizes. In addition, a wide variety of other stoppers can be used, such as a stopper provided on the left side and the right side of the image forming unit with a convex stopper support part via the stopper support part. Therefore, in the above-described first and second embodiments, the first unit support portion that supports one side portion of the image forming unit is provided as an engagement portion that is provided so as to be engageable with the stopper. Although the right-side protruding portions 56B and 86B provided on the right-side unit support plates 56 and 86 described above with reference to FIG. 25 are applied, the present invention is not limited to this, and the left-side unit support plate 55 is not limited to this. Various other engaging portions such as the left-side projecting portion 55B provided can be widely applied.

(3-6) Other Embodiment 6
Further, in the first and second embodiments described above, as another stopper provided on the other side portion of the image forming unit so as to be able to switch between the first state and the second state by rotating together with the stopper. The case where the left stopper 82 provided on the left side 80AS of the image forming units 72 to 75 described above with reference to FIGS. However, the present invention is not limited to this, a stopper having the same configuration as the right stopper 83 and the left stopper 82 provided on the right side surface 80BS of the image forming units 72 to 75, a stopper having various shapes and sizes, and a convex shape of the image forming unit. Other stoppers having various configurations can be widely applied, such as a stopper provided on the right side and the left side having the stopper support portion via the stopper support portion. Therefore, in the first and second embodiments described above, the second unit support portion that supports the other side portion of the image forming unit is provided as another engagement portion that can be engaged with another stopper. 1 to 25, the left overhanging portion 55B provided on the left unit support plate 55 is applied. However, the present invention is not limited to this, and the right unit support plate is not limited to this, and depending on the configuration of other stoppers. Other engaging portions of various other configurations such as the right-side overhanging portion 86B provided on the 86 can be widely applied.

(3-7) Other Embodiment 7
Furthermore, in the first and second embodiments described above, a pair for mounting the image forming unit at the mounting position is disposed so as to be able to support one side and the other side of the image forming unit. The case where the left unit support plate 55 and the right unit support plates 56, 86, 113, and 123 described above with reference to FIGS. 1 to 25 are applied as the first and second unit support portions has been described. However, the present invention is not limited to this, and the transfer unit 18 is not supported, and only the image forming units 10 to 13, 72 to 75, 100, 110, and 120 are replaced with the drum shaft 20A or the image forming units 10 to 13, 72. Plate-type or block-type left-side unit supported through cylindrical support protrusions provided on left side 40DA, 80AS and right side 40EA, 80BS, 101A, 111A, 121A of thru 75, 100, 110, 120 Various other configurations of the first and second unit support portions such as the support portion and the right unit support portion can be widely applied.

(3-8) Other Embodiment 8
Further, in the first and second embodiments described above, the image forming unit is supported by the first and second unit support portions and arranged so as to come into contact with the image carrier when mounted at the mounting position. The case where the transfer belt 27 and the intermediate transfer belt 134 described above with reference to FIGS. 1 to 25 are applied as the transfer portion that transfers the developer image on the image carrier has been described. However, the present invention is not limited to this, and various other transfer portions such as a transfer roller that is in direct contact with the photosensitive drums 20 to 23 can be widely applied.

(3-9) Other Embodiment 9
Further, in the first and second embodiments described above, one side of the image forming unit and the first unit support portion supporting the one side can be switched between the first state and the second state. The stoppers 60, 103 and the right stopper 83 provided on the right side surfaces 40EA, 80BS, 101A of the image forming units 10 to 13, 72 to 75, 100 described above with reference to FIGS. The case where the stoppers 114, 116, and 124 provided on the right unit support plate 113 are applied has been described. However, the present invention is not limited to this, and the stopper and the left unit support plate 55 have the same configuration as the stoppers 60 and 103 and the right stopper 83 provided on the left side surfaces 40DA and 80AS of the image forming units 10 to 13, 72 to 75, 100. Various stoppers having various configurations such as stoppers 114, 116, and 124 to be provided and stoppers having various shapes and sizes can be widely applied. Therefore, in the first and second embodiments described above, the right unit support described above with reference to FIGS. 1 to 25 is used as the engaging portion provided on the other side of the one side surface and the first unit support portion of the image forming unit. The right overhang portions 56B and 86B provided on the plates 56 and 86 and the engagement portions 112 and 122 provided on the right side surfaces 111A and 121A of the image forming units 110 and 120 are applied. Not limited to this, depending on the configuration of the stopper, the left overhanging portion 55B provided on the left unit support plate 55 and the left side surfaces 40DA and 80AS of the image forming units 10 to 13, 72 to 75, 100, 110, and 120 are provided. Various other configurations of the engaging portions such as the engaging portions 112, 112 and engaging portions of various shapes and sizes can be widely applied.

(3-10) Other Embodiment 10
Furthermore, in the first and second embodiments described above, the one-side gap regulating portion that is provided on one side of the image forming unit and regulates the gap with one side of the first unit support portion, and the image forming unit As other side gap regulating parts provided on the other side and regulating the gap with one side of the second unit support part, the left gap regulating parts 40DC and 80AU and the right gap regulating parts 40EC and 80BU described above with reference to FIGS. The case where it was applied was described. However, the present invention is not limited to this, and when the image forming units 10 to 13, 72 to 75, 100, 110, and 120 are inserted between the left unit support plate 55 and the right unit support plates 56, 86, 113, and 123. In addition to the left side gap restricting part and the right side gap restricting part that do not particularly have a function of correcting the positional deviation of the printer in the left-right direction, the one side gap restricting part and the other side gap restricting part in various other configurations are widely used. Can be applied.

(3-11) Other Embodiment 11
Further, in the first and second embodiments described above, the transfer rollers 28 to 31 and the primary transfer roller 135 described above with reference to FIGS. 1 to 25 are used as transfer members that are disposed to face the image carrier via a belt. The case of applying thru 138 has been described. However, the present invention is not limited to this, such as a conductive block to which a voltage can be applied for transferring the toner image on the photosensitive drums 20 to 23 to the surface of the printing medium 5 or the surface of the intermediate transfer belt 134. Various other types of transfer members can be widely applied.

  The present invention can be used for an image forming apparatus such as a color printer, a monochrome printer, an MFP, a facsimile machine, a multi-function machine, and a copying machine.

  1, 70, 130 ... Color printer, 10 to 13, 72 to 75, 100, 110, 120 ... Image forming unit, 20 to 23 ... Photosensitive drum, 20A ... Drum shaft, 20AX ... Fitting groove, 27... Transfer belt, 28 to 31... Transfer roller, 40, 80, 101, 111, 121... Unit housing, 40DA, 80AS .. Left side, 40DC, 80AU .. Left side gap regulating portion, 40EA, 80BS , 101A, 111A, 121A ... right side, 40EC, 80BU ... right side gap regulating portion, 55 ... left side unit support plate, 55A, 56A, 86A ... one side, 55B ... left side overhanging portion, 56, 86, 113, 123... Right side unit support plate, 56B, 86B ... Right side overhang, 60, 108, 114, 116, 124 ... Stopper, 81 ... Stopper connecting shaft, 82 ...... left stopper, 83 ...... right stoppers, 112, 122 ...... engagement portion, 134 ...... intermediate transfer belt 135 to 138 ...... primary transfer roller.

Claims (13)

The housing body,
A hinge,
An open / close cover attached to the housing body through the hinge so as to be openable and closable;
A plurality of image forming units rotatably provided with an image carrier for carrying a developer image;
A pair for mounting the plurality of image forming units at a plurality of mounting positions, which are disposed in the casing main body so as to be able to support one side and the other side of the plurality of image forming units. First and second unit support portions,
A plurality of the image forming units are arranged so as to come into contact with the plurality of image carriers when supported by the first and second unit support portions and mounted at the plurality of mounting positions. A transfer portion for transferring the developer image on the body;
A stopper provided on each of the one side portions of the plurality of image forming units and individually operated to switch between the first state and the second state;
The hinge is
Provided on one edge side of the casing body and the opening / closing cover, the other edge of the opening / closing cover can be opened and closed with respect to the casing body,
The first and second unit support portions are
The first unit support portion is disposed on the other edge side of the housing body portion and the opening / closing cover, and the second unit support portion is disposed on the one edge side of the housing body portion and the opening / closing cover. Thus, when supporting any of the image forming units, the stopper is positioned on the other edge side of the housing main body and the opening / closing cover, and when the stopper is in the first state, The image forming unit is supported at the mounting position, and when the stopper is in the second state, the image forming unit is supported at a separation position where the image carrier is separated from the transfer unit,
The stopper is
When the image forming unit is supported by the first and second unit support portions and operated in the mounted position, the image forming unit is switched from the first state to the second state. An image forming apparatus that is displaced from the mounting position to the separation position. The stopper is
When the image forming unit is operated in a state where the image forming unit is supported at the separated position by the first and second unit support portions, the image forming unit is moved from the second state to the first state to move the image forming unit to the separated position. The image forming apparatus according to claim 1, wherein the image forming apparatus is mounted by being displaced from the mounting position to the mounting position. The stopper is
The image forming apparatus according to claim 1, wherein the image forming apparatus is switched to the first state and the second state by a rotation operation. An image forming unit in which an image carrier for carrying a developer image is rotatably provided;
A pair of first and second unit support portions that are arranged to face each other so as to support one side and the other side of the image forming unit, and for mounting the image forming unit at a mounting position;
When the image forming unit is supported by the first and second unit support portions and mounted at the mounting position, the image forming unit is disposed so as to come into contact with the image carrier, and the developer image on the image carrier is A transfer section to be transferred;
A first stopper provided on the one side of the image forming unit so as to be able to rotate and switch between a first state and a second state;
A second stopper provided on the other side of the image forming unit so as to rotate together with the first stopper and to be switched between a first state and a second state;
A first engagement portion provided on the first unit support portion for supporting the one side portion of the image forming unit so as to be engageable with the first stopper;
A second engaging portion provided on the second unit supporting portion for supporting the other side of the image forming unit so as to be engageable with the second stopper;
The first and second unit support portions are
When the first stopper and the second stopper do not engage with the first engaging portion and the second engaging portion in the first state, the image forming unit is supported at the mounting position, and the first stopper And when the second stopper is engaged with the first engagement portion and the second engagement portion in the second state, the image forming unit is supported at a separation position where the image carrier is separated from the transfer portion. And
The image forming unit includes:
It is detachably mounted at the mounting position by being inserted into and pulled out from one surface of the first and second unit support portions,
The first stopper and the second stopper are:
When rotating from the first state to the second state in a predetermined rotation direction which is opposite to the insertion side when the image forming unit is mounted with respect to the one surface of the first and second unit support portions, The image forming unit is engaged with the first engaging portion and the second engaging portion, and the image forming unit is lifted from the mounting position to the separation position, whereby the image forming unit is moved to the first and second unit support portions. An image forming apparatus for supporting at a distance. The image forming unit includes:
A fitting groove is formed on the other end of the shaft of the image carrier,
The first unit support is
A first support portion is formed on the one surface to support one end portion of the shaft as the one side portion side of the image forming unit at the mounting position and the separation position.
The second unit support is
On the one surface, a second support portion is formed that fits and supports the other end portion of the shaft with the fitting groove as the other side portion side of the image forming unit at the mounting position and the separated position;
The first stopper and the second stopper are:
When rotating from the first state to the second state in the rotational direction, after the second stopper is abutted against the second engaging portion, the first stopper is abutted against the first engaging portion. By engaging the first engagement portion and the second engagement portion and lifting the image forming unit from the mounting position to the separation position, the image is placed on the first and second unit support portions. The image forming apparatus according to claim 4, wherein a forming unit is supported at the separation position. An image forming unit in which an image carrier for carrying a developer image is rotatably provided via a shaft;
A pair of first and second unit support portions arranged to face each other so as to support one side and the other side of the image forming unit, and for mounting the image forming unit at a mounting position;
When the image forming unit is supported by the first and second unit support portions and mounted at the mounting position, the image forming unit is disposed so as to come into contact with the image carrier, and the developer image on the image carrier is A transfer section to be transferred;
A stopper provided on one of the one side surface of the image forming unit and the first unit support portion supporting the one side surface so as to be switchable between a first state and a second state;
An engagement portion provided on the other side of the one side surface and the first unit support portion of the image forming unit,
The stopper is
In the first state, the image forming unit is supported at the mounting position by the first and second unit support portions without engaging with the engagement portion, and in the second state, the image forming unit is engaged with the engagement portion. The first and second unit support portions support the image forming unit at a separation position that separates the image carrier from the transfer portion,
The image forming unit includes:
A fitting groove is formed on the other end of the shaft of the image carrier,
The first unit support is
On one side, a first support portion for supporting one end portion of said shaft at said one side of said image forming unit at the mounting position and the separation position is formed,
The second unit support is
On one side, the second support portion for supporting the other end of the shaft fitted with the fitting groove in the other side surface side of the image forming unit at the mounting position and the separation position is formed image Forming equipment. The first unit support is
The one surface is disposed to face the one side surface of the image forming unit,
The second unit support is
The one surface is disposed to face the other side surface of the image forming unit,
The image forming unit includes:
The other side surface gap regulating portion that regulates the gap between the other side surface and the one surface of the second unit support portion when mounted on the other side surface at the mounting position between the first and second unit support portions. The image forming apparatus according to claim 6. The image forming unit includes:
The one side surface gap regulating portion that regulates a gap between the one side surface and the one surface of the first unit support portion when the one side surface is mounted at the mounting position between the first and second unit support portions. The image forming apparatus according to claim 7. The image forming unit includes:
The first and second unit support portions are detachably mounted at the mounting position by being inserted into and pulled out from the one surface,
The stopper is
When the image forming unit is inserted between the one surface of the first and second unit support portions, the image forming unit reaches the mounting position without engaging with the engaging portion in the first state. The first and second unit support portions are supported, and in the second state, the first and second units are engaged by engaging the engagement portion and stopping the image forming unit at the separation position before the mounting position. The image forming apparatus according to claim 7, wherein the image forming apparatus is supported by a two-unit support unit. The transfer portion is
A belt disposed so as to come into contact with the image carrier when the image forming unit is supported by the first and second unit support portions and mounted at the mounting position;
The image forming apparatus according to claim 6, further comprising: a transfer member disposed to face the image carrier through the belt. The transfer portion is
The image forming apparatus according to claim 10, wherein the developer image on the image carrier is transferred to the print medium by the transfer member while the print medium is conveyed by the belt together with the image carrier. The transfer portion is
The image forming apparatus according to claim 10, wherein the developer image on the image carrier is transferred to the belt by the transfer member. A plurality of the image forming units;
The stopper is
Provided on one of the plurality of corresponding positions of the one side of the plurality of image forming units and the first unit support,
The engaging portion is
The image forming apparatus according to claim 6, wherein the image forming apparatus is provided at the other side of the one side surface of the plurality of image forming units and the plurality of corresponding positions of the first unit support portion.

Images