JP4353316B2 - Image forming apparatus and transfer roller unit - Google Patents

Description

  The present invention relates to an image forming apparatus and a transfer roller unit.

For example, in some image forming apparatuses such as a laser printer, a transfer roller alone can be detachably attached to the image forming apparatus. As an example of this, Patent Document 1 below discloses a transfer roller unit that includes a transfer roller, a handle portion that supports both ends of the transfer roller and can be gripped by an operator, and includes a pair of separate support members. Is disclosed that is mounted at a transfer position located on the back side through an opening formed in an apparatus main body of the image forming apparatus.
JP 2001-331848 A

  However, in the configuration of the above-mentioned Patent Document 1, the operator has to hold the handle portions of the pair of support members that are separate from each other and perform the attaching / detaching operation to the transfer position with both hands, and a relatively narrow opening. There was a problem that the attaching / detaching work on the back side of the unit was troublesome and the workability was poor.

  The present invention has been completed based on the above-described circumstances, and an object thereof is to provide an image forming apparatus and a transfer roller unit in which the transfer roller unit can be easily attached and detached with one hand. .

As a means for achieving the above object, an image forming apparatus according to the invention of claim 1 includes a transfer roller unit having a transfer roller for transferring a visible image formed on an image carrier to a recording medium. An image forming apparatus detachably mounted at a transfer position transferable to the recording medium transported on a transport path in the apparatus body, wherein the transfer roller unit includes the transfer roller and the transfer roller A pair of support portions that rotatably support the end portions of the device, and a holder having a connection portion that connects the pair of support portions and is provided with a handle portion, Is formed with an opening for inserting the transfer roller unit, and the holder protrudes rearward in the insertion direction into the opening, and the lower surface has a tapered surface inclined upward toward the protruding end. The rear end side in the insertion direction is an inclined surface that is inclined upward toward the rear end corresponding to the tapered surface of the protrusion, and is connected to the holder. An accommodation portion is provided that can be accommodated in a retreat position that is retreated from the conveyance path so as to slide the portion along the inclined surface.
<Glossary>
In the present invention, the “image carrier” includes not only a photosensitive drum (photosensitive member) but also an intermediate transfer member.
The “image forming apparatus” includes not only a copying machine such as a laser printer but also a facsimile machine and a multifunction machine having a printer function and a scanner function.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the transfer roller unit is inserted into the transfer position with the axial direction of the transfer roller being orthogonal to the insertion direction into the opening. The transfer position is a position where the transfer roller of the transfer roller unit mounted at the transfer position faces the image carrier with the conveyance path interposed therebetween.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the handle portion is an upper surface of the protruding portion, and the conveyance path is disposed at a longitudinal center portion of the transfer roller. It is provided so that it may not be interrupted.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the transfer roller is disposed opposite to the transfer roller with the transfer path interposed in the housing portion. An urging means for urging the image carrier is provided, and the pair of support portions are configured to support the transfer roller so as to be displaceable in the urging direction of the urging means. .

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the apparatus main body is provided with a holding unit that holds the holder in the retracted position so as not to be displaced. It is characterized by being.

According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the recording medium is disposed between the image carrier and the transfer roller on the upper surface of the protrusion. A guide portion for guiding is formed.
<Glossary>
Note that the “guide portion” may be, for example, a rib extending substantially along the transport direction or a roller provided to be rotatable around a rotation axis orthogonal to the transport direction.

  According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, a developing roller that contacts the image carrier and supplies a developer is provided, and the holder includes the developing roller. A receiving portion for receiving the developer leaking from the vicinity of the end of the roller is provided.

<Invention of Claims 1 and 2>
According to this configuration, the transfer roller unit includes the transfer roller, the pair of support portions that rotatably support the end portions of the transfer roller, and the connecting portion that connects the pair of support portions. And a holder. Therefore, it is possible to hold the connecting portion disposed over the entire length of the transfer roller with one hand and attach it to the transfer position. In addition, since the connecting portion of the holder is accommodated in the accommodating portion formed in the apparatus main body of the image forming apparatus, the conveyance path of the recording medium is not obstructed.

<Invention of Claim 3>
According to this structure, the handle part which an operator can pick is provided in the center part of a connection part, and this handle part does not block a conveyance path in the state in a retracted position.

<Invention of Claim 4>
According to this configuration, the transfer roller is urged toward the image carrier while being mounted at the transfer position, and accordingly, the transfer roller is displaced to a position where it is pressed against the image carrier. Accordingly, the positioning between the image carrier and the transfer roller can be performed with a relatively simple configuration with high accuracy.

<Invention of Claim 5>
According to this configuration, the holder in the retracted position is held by the holding means so that it cannot be displaced. Therefore, for example, the holder does not rattle during the image forming operation, and a stable transfer operation can be performed, and noise due to rattling can be prevented.

<Invention of Claim 6>
According to this configuration, the upper surface of the protrusion functions as a guide for guiding the recording medium between the image carrier and the transfer roller. With such a configuration, it is possible to stably convey the recording medium while reducing the size of the entire apparatus as compared with a configuration in which the guide portion is provided on the apparatus main body side. Further, by combining with the structure of claim 5, it becomes possible to convey the recording medium more stably.

<Invention of Claim 7>
According to this configuration, the holder is provided with the receiving portion for receiving the developer leaking from the vicinity of the end portion of the developing roller. Therefore, the configuration can be simplified as compared with the configuration in which the receiving portion is provided separately from the transfer roller unit, and the leaked developer can be collected by taking out the transfer roller unit from the apparatus main body. .

<Related technologies>
The related art will be described with reference to FIGS.
1. FIG. 1 is a cross-sectional side view of an essential part showing one related technique of a laser printer as an image forming apparatus. In FIG. 1, a laser printer 1 includes a feeder unit 4 for feeding a sheet 3 as a recording medium in a main body casing 2 and an image formation for forming a predetermined image on the fed sheet 3. Unit 5 etc. are provided.

  Here, in this related technology, as will be described later, the process cartridge 12 and the transfer roller unit 70 including the transfer roller 26 are separated from each other, and these are the apparatus main body 1a (laser printer) of the laser printer 1. In the first configuration, the process cartridge 12 and the transfer roller unit 70 are removed from each other independently. In addition, an opening / closing door 2a is provided on one side of the main casing 2 (the right side in FIG. 1) so as to be rotatable around the lower end (see FIGS. 1 and 3). When the opening / closing door 2a is opened, a passage 2b is formed to allow the process cartridge 12 and the transfer roller unit 70 to be inserted to a transfer position X and an image forming position Y described later. The opening end of the passage 2b corresponds to the opening of the present invention (hereinafter referred to as “opening 2c”).

(1) Configuration of Feeder Unit The feeder unit 4 includes a paper feed tray 43 that is detachably attached to the bottom of the main body casing 2, a paper pressing plate 6 provided in the paper feed tray 43, and a paper feed tray. The sheet feeding roller 7 and the sheet feeding pad 8 are provided above one end of the sheet 43, and the registration roller 9 is provided downstream of the sheet feeding roller 7 in the conveyance direction of the sheet 3.

  The sheet pressing plate 6 can stack the sheets 3 in a stacked manner, and is supported so that the end far from the sheet feeding roller 7 can swing, and the near end rotates in the vertical direction. It is made possible, and is biased upward by a spring (not shown) from the back side. Therefore, the sheet pressing plate 6 is rotated downward against the urging force of the spring with the end portion far from the sheet feeding roller 7 as a fulcrum as the amount of stacked sheets 3 increases. The paper feed roller 7 and the paper feed pad 8 are arranged to face each other, and the paper feed pad 8 is pressed toward the paper feed roller 7 by a spring 10 provided on the back side of the paper feed pad 8. .

  The uppermost sheet 3 on the sheet pressing plate 6 is pressed toward the sheet feeding roller 7 by a spring (not shown) from the back side of the sheet pressing plate 6, and the sheet feeding roller 7 and the sheet feeding are rotated by the rotation of the sheet feeding roller 7. After being sandwiched between the pads 8, the sheets are fed one by one. The fed paper 3 is sent to a registration roller 9 by a paper feed roller 7. The registration roller 9 is composed of two rollers, a driving roller 44 provided on the main body casing 2 side and a driven roller 45 provided on the process cartridge 12 side, which will be described later. 3 is sandwiched between the driving roller 44 and the driven roller 45, and is sent to the image forming unit 5 after a predetermined registration.

(2) Configuration of Image Forming Unit The image forming unit 5 includes a scanner unit 11, a process cartridge 12, a transfer roller unit 70, a fixing unit 13, and the like.
(A) Configuration of Scanner Unit The scanner unit 11 is provided in the upper part of the main body casing 2 and has a laser light emitting unit (not shown), a polygon mirror 14 that is rotationally driven, lenses 15 and 16, and reflecting mirrors 17 and 18. , 19, and the like, and a laser beam based on predetermined image data emitted from the laser light emitting unit, as indicated by a chain line, polygon mirror 14, lens 15, reflecting mirrors 17, 18, lens 16, reflecting mirror 19. Are passed or reflected in this order to irradiate the surface of a photosensitive drum 21 (corresponding to the “image carrier” of the present invention) of the process cartridge 12 described later by high-speed scanning.

(B) Configuration of Process Cartridge Next, the process cartridge 12 will be described with reference to FIG. As shown in the figure, the process cartridge 12 does not include the transfer roller 26, and the transfer roller 26 is separated from the process cartridge 12 as a transfer roller unit 70. That is, the transfer roller 26 can be attached to and detached from the apparatus main body 1a independently of the process cartridge 12.

  FIG. 2 is an enlarged side sectional view showing the process cartridge 12. In the figure, a process cartridge 12 is disposed below the scanner unit 11 and is detachably mounted on the main body casing 2, and a photosensitive drum 21, a developing cartridge 36, and a scorotron charger 25. Etc. The developing cartridge 36 is detachably attached to the drum cartridge 20 and includes a developing roller 22, a layer thickness regulating blade 23, a supply roller 24, a toner box 27, and the like.

  The toner box 27 is filled with a positively charged non-magnetic one-component toner as a developer. Examples of the toner include polymerizable monomers such as styrene monomers such as styrene, and acrylic monomers such as acrylic acid, alkyl (C1 to C4) acrylate, and alkyl (C1 to C4) methacrylate. Polymerized toners obtained by copolymerization by a known polymerization method such as suspension polymerization are used. Such a polymerized toner is spherical and has very good fluidity. Such a toner is blended with a colorant such as carbon black, wax, and the like, and an additive such as silica is added to improve fluidity. The particle diameter is about 6 to 10 μm.

  The toner in the toner box 27 is agitated by an agitator 29 supported by a rotating shaft 28 provided at the center of the toner box 27 and discharged from a toner supply port 30 opened at a side portion of the toner box 27. . Note that a toner remaining amount detection window (not shown) is provided on the side wall of the toner box 27 and is cleaned by a cleaner 39 supported by the rotary shaft 28.

  A supply roller 24 is disposed at a side position of the toner supply port 30 so as to be rotatable in the direction of the arrow (counterclockwise), and the developing roller 22 faces the supply roller 24 in the direction of the arrow ( It is arranged to be rotatable counterclockwise. The supply roller 24 and the developing roller 22 are in contact with each other in a state where each of them is compressed to some extent.

  The supply roller 24 has a metal roller shaft covered with a roller made of a conductive foam material. The developing roller 22 has a metal roller shaft covered with a roller made of a conductive rubber material. More specifically, the roller portion of the developing roller 22 has a urethane rubber or silicone rubber coating layer containing fluorine on the surface of a roller body made of conductive urethane rubber or silicone rubber containing carbon fine particles. It is covered. A predetermined developing bias is applied to the developing roller 22 with respect to the photosensitive drum 21.

  In addition, a layer thickness regulating blade 23 is disposed in the vicinity of the developing roller 22. The layer thickness regulating blade 23 includes a blade body 37 made of a metal leaf spring material, and a pressing portion 38 having a semicircular cross section made of an insulating silicone rubber provided at the tip of the blade body 37. The end of the blade body 37 opposite to the pressing portion 38 is supported by the developing cartridge 36 near the developing roller 22, and the pressing portion 38 is pressed against the developing roller 22 by the elastic force of the blade body 37. It is configured as follows.

  The toner discharged from the toner supply port 30 is supplied to the developing roller 22 by the rotation of the supplying roller 24. At this time, the toner is positively frictionally charged between the supplying roller 24 and the developing roller 22, and further developed. As the developing roller 22 rotates, the toner supplied onto the roller 22 enters between the pressing portion 38 of the layer thickness regulating blade 23 and the developing roller 22, where the toner is more sufficiently frictionally charged and constant. It is carried on the developing roller 22 as a thin layer.

  The photosensitive drum 21 is disposed at a side position of the developing roller 22 so as to be rotatable in the arrow direction (clockwise) in a state of facing the developing roller 22 with a predetermined interval. The photosensitive drum 21 is formed of a positively chargeable photosensitive layer having a drum body grounded and a surface portion made of polycarbonate or the like.

  The scorotron charger 25 is disposed above the photosensitive drum 21 at a predetermined interval so as not to contact the photosensitive drum 21. The scorotron charger 25 is a positively charged scorotron charger that generates corona discharge from a charging wire such as tungsten, and is configured to uniformly charge the surface of the photosensitive drum 21 to a positive polarity. ing.

  The surface of the photosensitive drum 21 is uniformly positively charged by the scorotron charger 25 and then exposed by high-speed scanning of the laser beam from the scanner unit 11 to form an electrostatic latent image based on predetermined image data. Is done. Next, the electrostatic latent image formed on the surface of the photosensitive drum 21 when the positively charged toner carried on the developing roller 22 comes into contact with the photosensitive drum 21 by the rotation of the developing roller 22. That is, the surface of the photosensitive drum 21 that is uniformly positively charged is supplied to a portion of the photosensitive drum 21 that is exposed to a laser beam and the potential of which is lowered, and is selectively carried to be visualized. Development (formation of a toner image) is achieved.

  A brush support plate 51 that extends obliquely upward is integrally formed from the front lower end of the drum cartridge 20. A cleaning brush 52 is provided on the brush support plate 51. The cleaning brush 52 includes a brush holder 53 and a brush 54. The brush holder 53 is provided between the brush support plates 51, and the brush 54 is provided on the brush holder 53 so as to face the photosensitive drum 21. The brush 54 is made of a conductive member, and is applied with a bias voltage from a high voltage power supply circuit (not shown) provided in the apparatus main body 1a to remove paper dust adhering to the photosensitive drum 21.

(C) Configuration of Transfer Roller Unit As shown in FIG. 1, the transfer roller unit 70 can rotate the transfer roller 26 and the roller shaft 26a of the transfer roller 26 (corresponding to the “rotary shaft” of the present invention). It comprises a holder 71 for holding. Of these, the transfer roller 26 includes a roller 26b made of a conductive rubber material, leaving the end portions 26c and 26c (corresponding to the “end portion of the transfer roller” of the present invention) at both ends of the metal roller shaft 26a. It is configured to be covered. The specific configuration of the holder 71 will be described later.
A predetermined transfer bias is applied to the photosensitive drum 21 to the transfer roller 26 of the transfer roller unit 70 mounted at the transfer position X. Therefore, the visible image carried on the photosensitive drum 21 is transferred to the sheet 3 while the sheet 3 passes between the photosensitive drum 21 and the transfer roller 26.

(D) Configuration of Fixing Unit As shown in FIG. 1, the fixing unit 13 is disposed on the downstream side of the process cartridge 12, and includes a heating roller 32, a pressing roller 31 pressed against the heating roller 32, and these heating rollers 32. And a conveyance roller pair 33 provided on the downstream side of the pressing roller 31. The heating roller 32 is made of a metal and has a halogen lamp for heating, and the toner transferred onto the paper 3 in the process cartridge 12 is passed while the paper 3 passes between the heating roller 32 and the pressing roller 31. Then, the sheet 3 is transported to the paper discharge path 56 by the transport roller 33. The paper 3 sent to the paper discharge path 56 is sent to the paper discharge roller 34 and is discharged onto the paper discharge tray 35 by the paper discharge roller 34.

  In the laser printer 1, the toner remaining on the photosensitive drum 21 after being transferred onto the sheet 3 by the transfer roller 26 is recovered by the developing roller 22, and the residual toner is recovered by a so-called cleanerless system. . If the toner remaining on the photosensitive drum 21 is collected by such a cleaner-less method, there is no need to provide a cleaning device such as a blade or a waste toner storage unit, so that the configuration of the device is simplified, the size is reduced, and the cost is reduced. Can be achieved.

2. Configuration for attaching / detaching the transfer roller unit and the process cartridge As shown in FIGS. 1 and 3, when the opening / closing door 2a of the apparatus main body 1a is opened, the sheet conveyed from the feeder unit 4 to the lower side of the passage 2b. 3 conveyance path 57 is exposed. Hereinafter, the direction from the opening / closing door 2a (opening 2c) toward the back side of the passage 2b (the direction from the right side to the left side in the figure) will be described as the front of the insertion direction.

In this related technique, the process cartridge 12 is inserted into the image forming position Y by being inserted from the opening 2c with the axial direction (longitudinal direction) of the photosensitive drum 21 orthogonal to the insertion direction. It has become. Here, the image forming position Y refers to a position where the photosensitive drum 21 faces and contacts the transfer roller 26 mounted at the transfer position X, which will be described below, with the conveyance path 57 interposed therebetween.
On the other hand, the transfer roller unit 70 is configured to be inserted from the opening 2c and mounted at the transfer position X in a state where the axial direction (longitudinal direction) of the transfer roller 26 is also orthogonal to the insertion direction. Here, the transfer position X refers to a position where the transfer roller 26 is opposed to and in contact with the photosensitive drum 21 of the process cartridge 12 mounted at the image forming position Y with the conveyance path 57 interposed therebetween.

(1) Configuration for attaching / detaching a process cartridge As shown in FIG. 3, a pair of opposing walls (only the opposing wall 60 on the right side is shown) facing each other in the width direction of the passage 2b (the depth direction in the drawing). Each has a guide groove 61 that is recessed outward in the width direction. The guide groove 61 extends so as to gradually become narrower from the opening 2c toward the front side in the insertion direction. For example, the end of the roller shaft 21a of the photosensitive drum 21 projecting from both side surfaces of the process cartridge 12 inserted from the opening 2c is guided by the guide groove 61, and as shown in FIG. The guide groove 61 is positioned and held at the tip of the guide groove 61 in the insertion direction.

  Note that three electrodes 62 connected to, for example, a high-voltage power source (not shown) provided on the apparatus main body 1a side are exposed at the front portion of the guide groove 61 in the right facing wall 60 of the passage 2b. These are connected to an electrode (not shown) connected to the cleaning brush 52 protruding from the right side surface of the process cartridge 12 and the grid electrode of the scorotron charger 25 with the process cartridge 12 mounted at the image forming position Y. An electrode (not shown) and an electrode (not shown) connected to the charging wire of the scorotron charger 25 are elastically contacted, respectively, and serve to apply a bias voltage to the cleaning brush 52 and the scorotron charger 25.

(2) Transfer roller unit and configuration for attaching / detaching it (a) Specific configuration of holder of transfer roller unit The holder 71 of the transfer roller unit 70 can rotate the transfer roller 26 as shown in FIGS. A pair of support portions 72 and 72, and a connecting portion 73 having a length substantially equal to that of the roller shaft 26a and having a rectangular plate shape as a whole, and connecting the pair of support portions 72 and 72. Configured.
Among these, as shown in FIG. 4, the pair of support portions 72 and 72 are provided so as to protrude from both ends of one side surface along the longitudinal direction of the connection portion 73 toward the side. Each support portion 72 has an annular shape having an insertion hole 72a through which the end portion 26c of the roller shaft 26a of the transfer roller 26 is inserted. The insertion hole 72 is formed as a long hole that is long in a direction orthogonal to the flat plate-like connecting portion 73. That is, the transfer roller 26 supported by the support portion 72 is supported so as to be slightly movable in a direction orthogonal to the connecting portion 73.

  A plurality of ribs extending in a direction perpendicular to the transfer roller 26 are provided on one surface of the connecting portion 73 (the surface shown in FIG. 4. The surface on the upper side of FIG. 6. 74 (corresponding to the “guide portion” of the present invention) are arranged along the longitudinal direction of the connecting portion 73. In addition, the connecting portion 73 has a fan-like cross section projecting toward the lower surface 73b (surface opposite to the upper surface 73a) at both ends in the longitudinal direction, and has a recess 75a opened from the upper surface 73a. A portion 75 is provided. When the transfer roller unit 70 is in a retracted position, which will be described later, the toner collecting unit 75 is located below the end of the developing roller 22 of the process cartridge 12 positioned at the image forming position Y and leaks from the vicinity of the end. This is for collecting the toner.

As shown in FIG. 6, the recess 75a of the toner collecting portion 75 has an arc shape centering on an axis parallel to the transfer roller 26 as a whole, and the opening end side thereof is directed toward the upper surface 73a. It is formed in a tapered shape and wide. With such a configuration, when the holder 71 is set to a protruding position, which will be described later, the toner collected in the recess 75a can be prevented from remaining outside the recess 75a and leaking outside.
As shown in FIGS. 1 and 5 and the like, the lower surface 73b of the connecting portion 73 is formed with an upright fan-shaped handle portion 76 that can be picked up by the operator at the center in the longitudinal direction.

(B) Configuration for Accommodating Transfer Roller Unit Next, the configuration on the apparatus main body 1a side for accommodating the transfer roller unit 70 will be mainly described with reference to FIGS. 7 and 9, the upper direction of the paper (in the direction of the white arrow) is the conveyance direction of the paper 3.

  As shown in FIGS. 7 and 8, a transfer position X below the conveyance path 57 of the sheet 3 (a position below the photosensitive drum 21 of the process cartridge 12 mounted at the image forming position Y) is included in the transfer roller unit 70. The transfer roller accommodating portion 63 that accommodates the transfer roller 26 portion, and the holder accommodating portion 64 that is adjacent to the upstream side of the transfer roller accommodating portion 63 and that can accommodate the connecting portion 73 portion of the holder 71, pass through the conveyance path 57. It extends so as to cross. The transfer roller unit 70 lies so as to lie on the transport path 57 at the projecting position where the connecting portion 73 of the holder 71 projects from the transport path 57 in a state where the transfer roller 26 portion is housed in the transfer roller housing section 63. It is configured to be rotatable between a retreat position and a retreat position.

  This will be specifically described below. The transfer roller accommodating portion 63 is an accommodating groove that can accommodate the transfer roller 26, and a bearing member 65 having U-shaped bearing grooves 65 a formed on the upper surface at both ends in the longitudinal direction on the bottom surface thereof. Is fixed via a spring 66 as a biasing means. Accordingly, the transfer roller 26 supported by the bearing member 65 is urged upward.

  On the other hand, the holder accommodating portion 64 forms a recess having a rectangular cross section with a depth corresponding to the thickness of the connecting portion 73 of the holder 71 as a whole, and the toner collecting portions 75 of the connecting portion 73 are provided at both ends thereof. A pair of insertable first insertion portions 67, 67 are formed as openings, and a second insertion portion 68 into which the handle portion 76 of the connecting portion 73 can be inserted is formed at the center (see FIG. 7). .

(C) Configuration for holding the holder in the retracted position As shown in FIGS. 8 and 9, engagement protrusions are provided at both ends of the side end surface opposite to the transfer roller 26 in the connecting portion 73 of the transfer roller unit 70. On the other hand, engagement holes 69 and 69 for engaging with the engagement protrusions 77 and 77 are formed in portions corresponding to the engagement protrusions 77 and 77 in the holder accommodating portion 64, respectively. Has been. Thereby, the holder 71 can be positioned and fixed in the state accommodated in the holder accommodating portion 64, that is, in the retracted position.

  A plurality of ribs 80 are erected on the upstream side of the holder accommodating portion 64 so as to be connected to the ribs of the holder 71 at the retracted position. A communication hole 81 communicating with the holder accommodating portion 64 is formed at the center position of the portion where the rib 80 is formed, and the operation puts a finger into the communication hole 81 to connect the connection portion of the holder 71. The engagement between the engagement protrusion 77 and the engagement hole 69 can be released by pushing 73 upward from the lower surface 73b side.

3. Replacement Operation of Transfer Roller Unit For example, when the transfer roller 26 of the transfer roller unit 70 needs to be replaced due to deterioration or the like, the process cartridge 12 is removed by opening the door 2a as shown in FIG. A finger is put into the communication hole 81 formed above, and the connecting portion 73 of the holder 71 is pushed up and tilted to the protruding position as shown in FIG. 10 (in the direction of the white arrow B in FIG. 10). Then, the transfer roller unit 70 can be removed from the transfer position X by grasping and pulling the handle portion 76 protruding from the lower surface 73 b of the connecting portion 73.

  Then, the handle portion 76 of the new transfer roller unit 70 is picked and the transfer roller 26 is attached to the bearing member 65 of the transfer roller accommodating portion 63, and the connecting portion 73 of the holder 71 is tilted in the direction indicated by the white arrow A in FIG. It is accommodated in the holder accommodating portion 64. Thereby, the engagement protrusion 77 and the engagement hole 69 are engaged, and the holder 71 is positioned and fixed in the holder accommodating portion 64. Then, the process cartridge 12 is mounted at the image forming position Y. At this time, as shown in FIG. 11, the holder 71 of the transfer roller unit 70 is positioned and fixed to the holder accommodating portion 64. As described above, the insertion hole 72a of the support portion 72 of the holder 71 is a long hole. Thus, the transfer roller 26 can move up and down while in the retracted position, and comes into contact with the spring 66 so as to press upward, that is, against the photosensitive drum 21. Thus, the replacement operation of the transfer roller unit 70 is completed.

4). Effects of the Related Technology (1) According to the related technology, the transfer roller unit 70 includes a pair of support portions 72 and 72 that rotatably support the transfer roller 26 and the end portion 26c of the transfer roller 26, respectively. A holder 71 having a connecting portion 73 that connects the pair of support portions 72 and 72 to each other is provided. Accordingly, the connecting portion 73 disposed over the entire length of the transfer roller 26 can be grasped with one hand and attached to the transfer position X. Moreover, since the connecting portion 73 of the holder 71 is accommodated in the holder accommodating portion 64 formed in the apparatus main body 1a, the conveyance path 57 of the paper 3 is not blocked.
(2) Further, in the state where the holder 71 is disposed at the transfer position X, the holder 71 is rotated between a retracted position retracted from the transport path 57 (see FIG. 11) and a projecting position projected from the transport path 57 (see FIG. 10). Can be moved. Therefore, when the transfer roller unit 70 is attached / detached, the attaching / detaching operation can be easily performed by the projecting position where the connecting portion 73 is easily grasped.

(3) Furthermore, a handle portion 76 that can be picked by an operator is provided at the center of the connecting portion 73, and the handle portion 76 is in a state where it is in the retracted position so as not to block the transport path 57. It is accommodated in the accommodating portion 64. Accordingly, since the handle portion 76 is not exposed to the conveyance path 57 side, it is possible to prevent, for example, toner or dust from adhering to the handle portion 76, and it is not necessary to get the hands dirty during the attaching / detaching operation.
(4) Further, the transfer roller 26 is urged toward the photosensitive drum 21 by the spring 66 in the state where it is mounted at the transfer position X, and accordingly, the transfer roller 26 is displaced to a position where it is pressed against the photosensitive drum 21. Accordingly, the positioning between the photosensitive drum 21 and the transfer roller 26 can be performed with a relatively simple configuration with high accuracy.

(5) Further, the holder 71 in the retracted position is held so as not to be displaced by being locked by the engaging protrusion 77 and the engaging hole 69. Therefore, for example, the holder 71 does not rattle during an image forming operation, and a stable transfer operation can be performed, and noise due to rattling can be prevented.
(6) The connecting portion 73 of the holder 71 has a rib 74 formed on the surface exposed to the conveyance path 57 side (the upper surface 73 a), and guides the sheet 3 between the photosensitive drum 21 and the transfer roller 26. Function as. With such a configuration, it is possible to stably convey the sheet 3 while reducing the size of the entire apparatus as compared with a configuration in which a guide portion is provided on the apparatus main body 1a side. In addition, since the holder 71 is positioned and fixed by the engagement of the engagement protrusion 77 and the engagement hole 69, the paper 3 can be more stably conveyed.

  (7) Further, in this related technique, the holder 71 is provided with a toner collecting portion 75 for receiving toner (developer) leaking from the vicinity of the end portion of the developing roller 22. Accordingly, the configuration can be simplified compared to a configuration in which a toner collecting unit is provided separately from the transfer roller unit 70, and the leakage toner can be collected by removing the transfer roller unit 70 from the apparatus main body. Can do.

<Embodiment>
12-14 illustrate one embodiment. The difference from the related art is the configuration of the holder of the transfer roller unit and the accommodating portion for accommodating the transfer roller unit, and the other points are the same as the related art. Accordingly, the same reference numerals as those in the related art are assigned and the redundant description is omitted, and only different points will be described next. In FIG. 14, the white arrow direction is the conveyance direction of the paper 3.

1. Configuration of Transfer Roller Unit As shown in FIGS. 12 and 13, the holder 91 of the transfer roller unit 90 according to the present embodiment includes an elongated box portion 92 having an open top surface and a side surface from one side of the box portion 92. And a projecting portion 93 which is a tapered surface 93a inclined upward as the lower surface side is separated from the box portion 92.

  Among these, the box part 92 is accommodated in the state in which the transfer roller 26 exposes the upper surface side of the roller 26b. Also, bearing holes 92b and 92b are formed through both side walls 92a and 92a in the longitudinal direction of the box portion 92. The transfer roller 26 has an end portion 26c of the roller shaft 26a at the bearing holes 92b and 92b. It is inserted through 92b and is held rotatably with respect to the holder 91. Therefore, the both side wall portions 92a and 92a correspond to the “one pair of support portions” of the present invention, and the holder 91 portion other than the both side wall portions 92a and 92a corresponds to the “connecting portion” of the present invention.

  On the other hand, the protrusion 93 has a plurality of ribs 94 arranged on its upper surface along the longitudinal direction for guiding the paper 3 that is also transported through the transport path 57 between the photosensitive drum 21 and the transfer roller 26. . Further, toner recovery portions 95 and 95 for receiving toner leaking from the vicinity of the end portion of the developing roller 22 are formed in the upper surface of the protruding portion 93 at both end portions in the longitudinal direction. In addition, a pair of concave portions 96 and 96 into which human fingers can be inserted are formed on both sides of a rib 94 (hereinafter referred to as “central rib 94a”) located in the center on the upper surface of the protruding portion 93, respectively. The central rib 94a can be picked by inserting a finger into the recesses 96, 96. Therefore, the central rib 94a serves as the “handle” of the present invention.

2. Configuration for Accommodating Transfer Roller Unit An accommodating portion 100 capable of accommodating the transfer roller unit 90 is recessed on the conveyance path 57 in the apparatus main body 1a. Specifically, in the accommodating portion 100, the front side in the insertion direction has a depth capable of accommodating the box portion 92 of the holder 91 of the transfer roller unit 90, and the rear side in the insertion direction is the tapered surface 93a of the protruding portion 93. The inclined surface 100a is inclined upward toward the rear in the insertion direction. Therefore, when the transfer roller unit 90 is mounted, it can be accommodated in the accommodating portion 100 so as to slide along the inclined surface 100a, and the holder 91 can be disposed at the retracted position retracted from the conveyance path 57. (Refer to the transfer roller unit 90 shown by a two-dot broken line in FIG. 12). As in the related art, the holder 91 is positioned and fixed with respect to the accommodating portion 100 by the engagement between the engagement protrusion 77 and the engagement hole 69.

  When the transfer roller unit 90 is to be removed, the engagement between the engagement protrusion 77 and the engagement hole 69 is released by putting a finger into the communication hole 81 similar to the related technique and pushing the protrusion 93 upward. It can be pulled out so as to slide toward the opening 2c along the inclined surface 100a.

3. Effects of this Embodiment (1) According to this embodiment, the transfer roller unit 90 includes the transfer roller 26, a pair of support portions that rotatably support the end portion 26c of the transfer roller 26, and the pair of these support portions. And a holder 91 having a connecting portion for connecting the supporting portions to each other. Accordingly, the connecting portion disposed over the entire length of the transfer roller 26 can be grasped with one hand and attached to the transfer position X. Moreover, since the connecting portion of the holder 91 is accommodated in the accommodating portion 100 formed in the apparatus main body 1a, the conveyance path 57 of the paper 3 is not blocked.
(2) Moreover, the center rib 94a provided in the center position of the protrusion part 93 can be picked as a handle part, and attachment / detachment work can be performed.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention, and further, within the scope not departing from the gist of the invention other than the following. Various modifications can be made.
(1) In the related art, the holding means is based on the engagement between the engagement protrusion 77 and the engagement hole 69. However, the present invention is not limited thereto, and the holders 71 and 91 are held undisplaceable by screwing, for example. It may be a configuration. In the related art, the toner collecting portion 75 is formed to be slightly larger than the first insertion portion 67 and inserted so as to be press-fitted, or the handle portion 76 is slightly larger than the second insertion portion 68. It may be configured to hold the holder 71 so as not to be displaced by being formed so as to be inserted and press-fitted. Further, in the above embodiment, the holder 91 is held so as not to be displaceable by being formed so that the length in the longitudinal direction of the holder 91 is slightly longer than the length of the accommodating portion 100 and accommodated so as to be press-fitted. May be.

  (2) As the “guide portion”, the ribs 74 and 94 extending along the conveyance path 57 may be rollers (rotary rollers) provided so as to be rotatable around a rotation axis orthogonal to the conveyance path 57, for example. Good.

Cross-sectional side view of relevant parts of a laser printer according to related technology Side cross-sectional view showing enlarged process cartridge Cross-sectional side view of the main part of the laser printer showing a state in which the transfer roller unit and the process cartridge are removed from the apparatus main body. Top view of transfer roller unit Front view of transfer roller unit Side view of transfer roller unit View of the transfer roller housing and the holder housing from above Sectional drawing which expanded and showed the accommodating part for transfer rollers, and the accommodating part for holders The figure which looked at the state where the transfer roller unit was installed in the storage part for transfer rollers, and the storage part for holders from the upper part Enlarged sectional view showing the transfer roller unit in the protruding position Enlarged sectional view showing the transfer roller unit in the retracted position The expanded sectional view which shows the attachment or detachment state of the transfer roller unit of embodiment of this invention Top view of transfer roller unit View of the storage section from above

Explanation of symbols

1. Laser printer (image forming device)
DESCRIPTION OF SYMBOLS 1a ... Main body 2c ... Opening 3 Paper (recording medium)
12 ... Process cartridge 21 ... Photosensitive drum (image carrier)
26 ... Transfer roller 26c ... End portion 70, 90 ... Transfer roller unit 57 ... Conveying path 63 ... Transfer roller housing portion 64 ... Holder housing portion 66 ... Spring ( Energizing means)
69 ... engaging hole 71, 91 ... holder 72 ... support part 73 ... connecting part 74, 94 ... rib (guide part)
75, 95 ... Toner collection part 76 ... Handle part 77 ... Engagement protrusion 81 ... Communication hole 92a, 92a ... Both side wall part (support part)
94a ... Central rib (handle)
100 ... container X ... transfer position Y ... image forming position

Claims (7)

A transfer roller unit having a transfer roller for transferring a visible image formed on the image bearing member to a recording medium is placed at a transfer position at which the image can be transferred to the recording medium conveyed on the conveyance path in the apparatus main body. An image forming apparatus that is detachably mounted,
The transfer roller unit includes a pair of support portions that rotatably support the transfer roller, an end portion of the transfer roller, and a connection portion that connects the pair of support portions to each other and is provided with a handle portion. A holder having a portion,
The apparatus body is formed with an opening for inserting the transfer roller unit,
The holder has a protruding portion that protrudes rearward in the insertion direction into the opening, and whose lower surface is a tapered surface inclined upward toward the protruding end,
In the transport path, the rear end side in the insertion direction is an inclined surface that is inclined upward toward the rear end corresponding to the tapered surface of the protruding portion, and the connecting portion of the holder extends along the inclined surface. An image forming apparatus comprising: a housing portion that can be housed in a retracted position retracted from the conveyance path so as to slide. The transfer roller unit is configured to be inserted into the transfer position by being inserted in a state in which the axial direction of the transfer roller is orthogonal to the insertion direction into the opening,
The image forming apparatus according to claim 1, wherein the transfer position is a position where a transfer roller of a transfer roller unit mounted at the transfer position faces the image carrier with the conveyance path interposed therebetween. 3. The handle according to claim 1, wherein the handle is provided on an upper surface of the protrusion and at a central portion in a longitudinal direction of the transfer roller so as not to block the transport path. The image forming apparatus described. The accommodating portion is provided with an urging means for urging the transfer roller toward the image carrier that is opposed to the transfer roller with the conveyance path interposed therebetween.
4. The image according to claim 1, wherein the pair of support portions are configured to support the transfer roller so that the transfer roller can be displaced in a biasing direction of the biasing unit. 5. Forming equipment. The image forming apparatus according to claim 1, wherein the apparatus main body is provided with a holding unit that holds the holder in the retracted position so as not to be displaceable. 6. A guide portion for guiding the recording medium between the image carrier and the transfer roller is formed on an upper surface of the protruding portion. The image forming apparatus described. A developing roller for contacting the image carrier and supplying a developer;
The image forming apparatus according to claim 1, wherein the holder is provided with a receiving portion for receiving a developer leaking from the vicinity of an end portion of the developing roller.

Images