JP5104977B2 - Image forming apparatus and developing unit used in the image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic image forming apparatus such as a laser printer, a copying machine, and a facsimile machine, and a developing unit.

  The laser printer is configured such that a developing unit generally called a developing cartridge is detachable from a frame including a photosensitive drum. Among these, the developing cartridge includes a developing roller and a storing case for storing the developer, and the storing case is formed in an elongated shape along the axial direction of the developing roller. It is provided on the peripheral side surface of the storage case along the axial direction of the roller. The laser printer also includes a pressing member that presses the storage case so that the developing roller is pressed against the photosensitive drum, and a separation member that moves the storage case so as to separate the developing roller from the photosensitive drum. The laser printer configured as described above has a structure in which a force for pushing the developing unit storage case using the pressing member and a force for separating the developing unit using the separating member act on one point of the housing case. (Patent Documents 1 to 3).

However, when a force acts on the storage case at one point in this way, it is necessary to strongly reinforce the portion where the force acts and its periphery.
Therefore, among the conventional laser printers 1, there is a load separation type laser printer in which the force for pushing the storage case by the pressing member and the force for separating the storage case by the separating member do not act on one point ( Patent Document 4).
JP-A-11-133730 JP 2003-84647 A JP-A-2005-37680 JP 2001-343809 A

  However, since the load separation type laser printer is configured to push near the central portion in the longitudinal direction of the storage case of the developing unit, the storage case may bend. Therefore, the laser printer has to be reinforced by making the storage case thick.

  Accordingly, the present invention solves the above-described problems, does not increase the thickness of the storage case of the developing unit, and the image forming apparatus in which the force for pushing the storage case and the force for separating the storage case do not act on one point, and this image An object of the present invention is to provide a developing unit used in a forming apparatus.

In order to solve the above problems, an image forming apparatus of the present invention has an image carrier on which an electrostatic latent image is formed on a surface, and a developer is supplied to the image carrier to make the electrostatic latent image visible. A developer carrier that forms an image, a housing that includes the developer carrier, and that stores the developer supplied to the image carrier by the developer carrier, and the developer carrier as the image carrier. An image forming apparatus comprising: a pressing unit that presses the housing in a direction to press the housing; and a separating unit that moves the housing in a direction to move the developer carrier away from the image carrier. the housing includes an end side which is upright from each end of said developer carrying member in the axial direction perpendicular to the direction of said developer carrying member, said end side, in a direction parallel to the front Stories axis Provided with a projecting portion projecting outward along, the projecting portion is an acted portion on which the separating means acts, Some of the acting portion whose serial pressing means act is characterized by being located on the side end surface and the same surface.

Housing of images forming apparatus This, the operated portion der Ru collision portion which is spaced means acts, is projected to the outside along a direction parallel to the axial direction of the developer carrying member, the pressing means The operated part to be operated is located near the corner of the housing. Vicinity of the corner portions of the housing are in originally where rigidity is high, also, the image forming apparatus, provided with a collision portion to the housing, nor is not spaced directly by a force the housing. For this reason, the housing of the image forming apparatus of the present invention is not distorted unlike the conventional image forming apparatus.

Further, the image forming apparatus, are offset and butt portion and the working portion. Therefore, the reverse force is not repeatedly applied to the same place. Therefore, when the image forming apparatus, as in the conventional developing devices, without the portion where the collision portion and the working portion provided with robust structures may constitute a developing unit.

The developing unit applied to the image forming apparatus includes a developer carrier that supplies a developer to the image carrier and visualizes the electrostatic latent image formed on the surface of the image carrier. A developing unit comprising: a developer carrier , and a housing for accommodating the developer supplied to the image carrier by the developer carrier, wherein the housing is formed of the developer carrier. with an end side which is erected in the axial direction perpendicular to the direction of the developer carrier from each end, said end side, projecting that projects outward along the direction parallel to the front Stories axis The projecting portion is an actuated portion on which a separation means provided on the apparatus main body acts to move the housing in a direction to separate the developer carrier from the image carrier, Provided in the apparatus main body, which presses the housing in a direction in which the developer carrier is pressed against the image carrier. Some of the operated portion that pressure means acts are those located on the side end surface and the same surface.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a side sectional view showing a schematic configuration of a laser printer 1 as an image forming apparatus of the present embodiment. FIG. 2 is a side sectional view showing a schematic configuration of the laser printer 1 as the image forming apparatus of the present embodiment, and is an explanatory diagram for explaining a state in which the image forming unit 20 is taken out.

  As shown in FIG. 1, the laser printer 1 is a so-called direct tandem type color laser printer including four photosensitive drums 30 corresponding to black, cyan, magenta, and yellow colors. The laser printer 1 includes a main body casing 2 in which a paper feed unit 4 for feeding paper 3 as a recording medium, an image forming unit 20 and an image forming unit for forming an image on the fed paper 3 are provided. 20 is provided with a paper transporting section 35 for transporting the paper 3 with respect to 20. In the following description, the left and right directions are referred to as the left side and the right side as the right side of the drawing shown in FIG.

  A front cover 6 that can be opened and closed is provided on the left side of the main casing 2. As shown in FIG. 2, the front cover 6 is opened from the closed position that covers the left surface of the main casing 2 in a substantially vertical posture, and the upper end side is tilted leftward with the lower end portion as the center. It can be turned up to. By setting the front cover 6 to the open position, an image forming unit 20 (described later) accommodated in the main body casing 2 can be pulled out to the left. When the front cover 6 is in the closed position, the upper end thereof substantially coincides with the upper end of the main casing 2 as shown in FIG.

  The paper feed unit 4 includes a paper feed tray 7 that is detachably attached to the bottom of the main casing 2, a paper feed roller 8 and a separation pad 9 that are provided above the left end of the paper feed tray 7, A pickup roller 10 provided on the right side of the roller 8, a pair of paper dust removing rollers 11 disposed on the upper left side of the paper feeding roller 8, and a pair of registration rollers 12 </ b> A and 12 </ b> B provided above the paper dust removing roller 11. It has.

  The paper feed tray 7 is formed in a box shape having an opening at the top so that the paper 3 can be carried inside, and having a depth at which a fixed number of papers 3 can be stacked. The left side wall 13 provided at the left end portion of the paper feed tray 7 is arranged on the lower side of the front cover 6 on the left side of the main casing 2. The left side wall 13 is pulled to the left side to pull the paper feed tray 7. It can be pulled out horizontally to the left of the main casing 2. On the bottom surface of the paper feed tray 7, there is provided a paper pressing plate 7A on which the paper 3 can be stacked. The paper pressing plate 7A is rotatably supported at the right end and is not shown. The left end is biased upward by the spring. As a result, the sheets 3 stacked in the sheet feed tray 7 are urged upward on the left end side.

  The uppermost sheet 3 of the sheet feeding tray 7 is pressed toward the pickup roller 10 by the urging force of the sheet pressing plate 7A, and is directed between the sheet feeding roller 8 and the separation pad 9 by the rotation of the pickup roller 10. The transport is started. Then, the sheet 3 is turned and fed one by one when sandwiched between the sheet feeding roller 8 and the separation pad 9 by the rotation of the sheet feeding roller 8. The fed paper sheet is transported to the registration rollers 12A and 12B after the paper dust is removed by the paper dust removing roller 11.

  The registration rollers 12A and 12B are composed of a driving roller 12A and a driven roller 12B, and convey the sheet 3 onto a transfer belt 38 of a sheet conveyance unit 35 to be described later via the sheet feeding path 14 after registration. The paper feed path 14 is a conveyance path of the paper 3 curved in an arc shape, and is formed in a frame 21 of the image forming unit 20 described later.

  A scanner unit 18 is provided at the top of the main body casing 2. The scanner unit 18 irradiates the surface of a corresponding photosensitive drum 30 (described later) with a laser beam L for each color based on predetermined image data by high-speed scanning. The four laser beams L corresponding to the respective colors are emitted obliquely downward to the right from the bottom surface of the scanner unit 18. The optical paths of the laser beams L are arranged at regular intervals on the left and right sides, and are parallel to each other.

  In the main casing 2, a unit accommodating portion 19 is provided below the scanner portion 18, and an image forming unit 20 that can be pulled out to the left and is detachable is accommodated therein. The image forming unit 20 includes a frame 21. The frame 21 includes a photosensitive drum 30 as an image carrier, a scorotron charger 50 as a charger, four developing units 22 as developers, and A cleaning brush 33 is held.

  Each of the four developing units 22 is detachably attached to the frame 21 and corresponds to each color of black, cyan, magenta, and yellow. The developing unit 22 includes a box-shaped storage case 23 whose lower side is opened, and a toner storage chamber 24 filled with toner of each color is formed in the upper portion of the storage case 23. An agitator (not shown) is provided in the toner storage chamber 24, and the agitator is rotationally driven by the input of power from a motor (not shown) to stir the internal toner. A developing roller 26 is provided below the toner storage chamber 24.

  The developing roller 26 is rotatably supported by the housing case 23 of the developing unit 22. Further, the developing roller 26 is in contact with the photosensitive drum 30 in a state where the developing unit 22 is mounted on the frame 21. The developing roller 26 is configured by covering a metal roller shaft with a roller body made of conductive urethane rubber or silicone rubber containing carbon fine particles. The surface of the roller body is covered with a coating layer of urethane rubber or silicone rubber containing fluorine. A developing bias is applied to the developing roller 26 during development. The developing roller 26 is rotationally driven by the input of power from a motor (not shown).

  The toner discharged from the toner storage chamber 24 is supplied to a developing roller 26 from a supply roller (not shown) installed in the toner storage chamber. At this time, the toner is positively frictionally charged between the supply roller and the developing roller 26. The toner supplied onto the developing roller 26 is carried on the developing roller 26 as a thin layer having a constant thickness by a layer thickness regulating blade (not shown) installed in the toner storage chamber.

  The photosensitive drum 30 has a cylindrical shape, and a roller main body 30A formed by a positively chargeable photosensitive layer whose outermost layer is made of polycarbonate or the like, and an axial center of the roller main body 30A along the longitudinal direction of the roller main body 30A. And a metal roller shaft 30B as a shaft extending in the direction. The photosensitive drum 30 rotates around the roller shaft 30B by the roller shaft 30B being rotatably held by the frame 21. The photosensitive drum 30 is rotationally driven by input of power from a motor (not shown).

  The scorotron charger 50 is disposed opposite to the photosensitive drum 30 at a predetermined interval so that the charger wire 52 as a discharge line does not come into contact with the photosensitive drum 30 obliquely on the right side of the photosensitive drum 30. Yes. The scorotron charger 50 generates a corona discharge from the charger wire 52 to uniformly charge the surface of the photosensitive drum 30 to a positive polarity.

The cleaning brush 33 is disposed on the right side of the photosensitive drum 30 so as to face and contact the photosensitive drum 30.
The paper transport unit 35 is disposed below the image forming unit 20 mounted in the unit storage unit 19. The paper transport unit 35 includes a pair of belt support rollers 36 and 37 provided in parallel with each other on the right side and the left side, and a transport belt 38 spanned between the rollers 36 and 37. The belt support roller 36 on the right side is rotationally driven by the power of a motor (not shown) so that the transport belt 38 circulates and moves. Inside the conveyance belt 38, four transfer rollers 39 arranged to face the respective photosensitive drums 30 of the image forming unit 20 described above are provided at regular intervals in the left-right direction, and correspond to the respective photosensitive drums 30. A conveyance belt 38 is sandwiched between the transfer roller 39 and the transfer roller 39. A cleaning roller 40 is provided below the conveyor belt 38 for cleaning residual toner adhering to the conveyor belt 38. The sheet 3 sent out from the registration roller 12 passes through the paper feed path 14 and comes into contact with the vicinity of the upper left end of the transport belt 38, where it is electrostatically attracted to the upper surface of the transport belt 38 and It is conveyed to the right along with the circular movement.

  As the surface of the photosensitive drum 30 rotates, the surface of the photosensitive drum 30 is first uniformly charged positively by the scorotron charger 50 and then exposed by high-speed scanning of the laser light L from the scanner unit 18 to form on the paper 3. An electrostatic latent image corresponding to the image to be formed is formed.

  Next, when the developing roller 26 rotates, the positively charged toner carried on the developing roller 26 is formed on the surface of the photoconductive drum 30 when it comes into contact with the photoconductive drum 30. The electrostatic latent image, that is, the surface of the photosensitive drum 30 that is uniformly positively charged, is supplied to an exposed portion exposed to a laser beam and having a lowered potential. As a result, the electrostatic latent image on the photosensitive drum 30 is visualized, and a toner image by reversal development is carried on the surface of the photosensitive drum 30.

  Thereafter, the toner image carried on the surface of the photosensitive drum 30 is transferred to the transfer roller 39 while the sheet 3 conveyed by the conveying belt 38 passes through the transfer position between the photosensitive drum 30 and the transfer roller 39. Is transferred to the sheet 3 by the transfer bias applied to the sheet 3. The sheet 3 on which the toner image is transferred is then conveyed to the fixing device 42.

  The fixing device 42 is disposed on the right side of the paper transport unit 35 in the main body casing 2. The fixing device 42 includes a heating roller 43, a pressure roller 44, and the like disposed so as to face each other, and heat-fixes the toner image transferred onto the paper 3 onto the paper surface. The heat-fixed paper 3 is conveyed to a paper discharge roller 46 provided at the upper part of the main body casing 2 by a conveyance roller 45 disposed obliquely on the upper right side of the fixing device 42. On the upper surface of the main casing 2, a paper discharge tray 47 that is substantially horizontal on the left end side and inclined to the right side on the right end side is provided, and the image-formed paper 3 discharged from the paper discharge roller 46 is placed on the paper discharge tray 47. Is laminated.

Next, the developing unit 22 that is a characteristic configuration of the laser printer 1 of the present embodiment will be described.
FIG. 3 is an explanatory diagram of the developing unit 22 of the present embodiment. FIG. 3A is a side view of the developing unit 22 and a front view of the developing unit 22. 4 is a perspective view of the frame 21 to which the developing unit 22 of the present embodiment is attached. FIG. 5 is a side sectional view showing a schematic configuration of the laser printer 1 of the present embodiment. The developing unit 22 is attached to the frame 21. It is explanatory drawing for demonstrating a mode. 6 shows a state in which the pressing member 70 pushes the developing unit 22, and FIG. 7 shows a state in which the separating tool 80 separates the developing unit 22.

  As shown in FIG. 3B, the developing unit 22 used in the laser printer 1 of the present embodiment includes a box-shaped storage case 23, and the upper portion of the storage case 23 is filled with toner of each color. A toner storage chamber 24 is formed. An agitator (not shown) is provided in the toner storage chamber 24, and the agitator is rotationally driven by the input of power from a motor (not shown) to stir the internal toner. A longitudinal opening is formed below the housing case 23, and a developing roller 26 is provided in the opening.

  Among them, the storage case 23 is directed from each end in the axial direction of the developing roller 26 (see FIG. 3B) in a direction substantially perpendicular to the axial direction of the developing roller 26, as shown in FIG. And have end side surfaces 23a erected. Then, on these end side surfaces 23a, on the upper end opposite to the side on which the developing roller 26 is mounted, as shown in FIG. 3B, in the axial direction of the developing roller 26 A pair of protrusions 231 projecting outward along the parallel axis, and a pair of protrusions 232 projecting further outward from the tip of each protrusion 231 are formed. And these protrusion 231 and protrusion 232 are formed in the corner | angular part of the storage case 23, as shown to Fig.3 (a). On the other hand, a pair of guides projecting outward along the axis parallel to the axial direction of the developing roller 26, as shown in FIG. A protrusion 233 protrudes outward.

  Next, in the main body casing 2 of the laser printer 1 of this embodiment, as described above with reference to FIG. 2, when the front cover 6 is opened, the image forming unit 20 accommodated in the main body casing 2 is moved to the left. It can be pulled out. The image forming unit 20 includes the frame 21 as described above, and the frame 21 is configured to be disassembled into four blocks 21a. As shown in FIG. 4, each block 21a includes a photosensitive drum 30, a scorotron charger 50, a cleaning brush 33 (see FIG. 1), and the like. Each block 21 a includes a pair of mounting plate pieces 21 b extending upward from the respective axial ends of the photosensitive drum 30. The mounting plate piece 21b is formed with a guide groove portion 21c for guiding the developing unit 22 on the opposite mounting plate piece 21b side, that is, inside. The guide groove portion 21 c guides the developing unit 22 attached to each frame 21 so that the developing roller 26 contacts the photosensitive drum 30. Specifically, as shown in FIG. 5, the developing unit 22 is guided by the guide protrusion 233 attached to the tip side of the end side surface of the developing unit 22 sliding in the guide groove portion 21c.

  Next, as shown in FIG. 6, the laser printer 1 according to the present embodiment includes a pressing member 70 that presses the protrusion 231 in the main body casing 2. The pressing member 70 is a spiral spring, and is located at a position facing each protrusion 231 of each developing unit 22 when the image forming unit 20 is accommodated in the main body casing 2, and above the protrusion 231. It is installed inside. When each developing unit 22 is pressed by the pressing member 70, the developing roller 26 is pressed against the photosensitive drum 30.

  Further, as shown in FIG. 7, the laser printer 1 of the present embodiment includes a separating tool 80 that separates the image forming unit 20 accommodated in the main body casing 2 in a direction in which the developing roller 26 separates from the photosensitive drum 30. I have. The spacing member 80 is provided with a spacing piece 82 at one end of the rotating shaft 81, and the spacing piece 82 is attached at a position eccentric to the axis of the rotating shaft 81. The rotating shaft 81 is installed in parallel with the axis of the developing roller 26, and the separating piece 82 is installed below the protrusion 232. The separating tool 80 is separated from the protrusion 232 when the side portion on the short distance side from the rotation shaft 81 faces the rotation shaft 81, and is pressed when the side portion on the long side faces the rotation shaft 81. The protrusion 232 is pushed up against the urging force of the member 70.

The use of the laser printer 1 configured as described above has the following effects.
The storage case 23 of the laser printer 1 is structurally rigid with respect to the force applied in the direction along the end side surface 23a. The laser printer 1 according to the present embodiment includes the protrusions 231 and the protrusions 232 at the upper end on each end side surface 23a having high rigidity. Therefore, in the laser printer 1 of the present embodiment, the storage case 23 can be pressed and separated without pressing the storage case 23 as in the case of the conventional laser printer. Therefore, it is not necessary to make the storage case 23 thick.

  Further, since the projection 232 is formed outside the projection 231 and the projection 232 and the projection 231 are misaligned in the storage case 23 of the laser printer 1, a reverse force is not repeatedly applied to the same place. Therefore, in this laser printer 1, the developing unit can be configured without having a robust structure in the portion where the protrusion 231 and the protrusion 232 are provided unlike the conventional developing unit.

  The storage case 23 corresponds to the housing of the present invention. The developing roller 26 corresponds to the developer carrying member of the present invention. The protrusion 231 corresponds to the first protrusion of the present invention. The protrusion 232 corresponds to the second protruding portion of the present invention.

  Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and it is needless to say that the present invention can be implemented in various modes without departing from the gist of the present invention.

  For example, even if the actuated portion on which the pressing means corresponding to the protrusion 231 acts has the above effects, it does not necessarily have to be disposed on the end side surface 23a of the storage case 23. .

  Specifically, as shown in FIG. 8, the protrusions 232 protrude from the upper end on each end side surface 23 a toward the outside along an axis parallel to the axial direction of the developing roller 26. It is preferable that the outer side of the frame 21 straddling each guide side surface 21b is disposed. On the other hand, the protrusion 231 is preferably disposed inside the protrusion 232 and on the axis, in the vicinity of each end side surface 23a. Here, the vicinity is preferably a state where a part thereof is overlapped on the same surface as the end side surface 23a. Even if comprised in this way, the effect similar to the said embodiment can be acquired.

  In the above-described embodiment, the laser printer 1 having the structure in which the developing unit 22 is vertically disposed has been described. However, the above-described pressing member 70 and the separating tool 80 are added to the laser printer having the structure in which the developing unit 22 is horizontally disposed. May be installed. In this case, the pressing member 70 pushes the protrusion 231 of the developing unit 22 and presses the developing roller 26 against the photosensitive drum 30, while the spacing member 80 pushes the protrusion 232 of the developing unit 22 in the reverse direction to push the developing roller 26 to the photosensitive drum. Pull away from 30.

1 is a side sectional view showing a schematic configuration of a laser printer 1 as an image forming apparatus according to an embodiment. FIG. 2 is a side sectional view showing a schematic configuration of a laser printer 1 as an image forming apparatus of the present embodiment, and is an explanatory diagram for explaining a state where a frame 21 is taken out to the outside. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of a developing device of the present embodiment, where (a) is a side view of the developing device, and (b) is a front view of the developing device. It is a perspective view of the block 21a which comprises the flame | frame 21 of this embodiment. It is a side view of the block 21a which comprises the flame | frame 21 of this embodiment, and is explanatory drawing for demonstrating a mode that the developing unit 22 was attached to the block 21a. 1, the configuration around the developing unit 22 and the developing roller 26 is enlarged, and a state in which the pressing member 70 presses the developing unit 22 is shown. 1, the configuration around the developing unit 22 and the developing roller 26 is enlarged, and a state in which the spacer 80 separates the developing unit 22 is shown. FIG. 6 is an explanatory diagram of another example of the developing device of the present embodiment, in which (a) is a side view of the developing device, and (b) is a front view of the developing device.

DESCRIPTION OF SYMBOLS 1 ... Laser printer, 2 ... Main body casing, 3 ... Paper, 4 ... Paper feed part, 6 ... Front cover, 7 ... Paper feed tray, 7A ... Paper press plate, 8 ... Paper feed roller, 9 ... Separation pad, 10 ... Pickup roller, 11 ... paper dust removing roller, 12A ... registration roller, 12B ... drive roller, 13 ... left wall, 14 ... feed path, 18 ... scanner part, 19 ... unit housing part, 20 ... image forming frame, 21 ... Frame, 21a ... Block, 21b ... Mounting plate piece, 21c ... Guide groove, 22 ... Developing unit, 23 ... Accommodating case, 23a ... End side surface, 24 ... Toner accommodating chamber, 26 ... Developing roller, 30 ... Photoconductor drum, 30A ... Roller body, 30B ... Roller shaft, 33 ... Cleaning brush, 35 ... Paper conveying section, 36 ... Belt support roller, 38 ... Conveying belt, 39 ... Transfer roller, 40 ... -Rolling roller 42 ... Fixer 45 ... Conveying roller 46 ... Discharge roller 47 ... Discharge tray 50 ... Scorotron charger 52 ... Charger wire 70 ... Pressing member 80 ... Separating tool 81 ... Rotation Axis, 82 ... spacing piece, 231 ... projection, 232 ... projection, 233 ... guide projection

Claims (2)

An image carrier on which an electrostatic latent image is formed on the surface;
A developer carrier for supplying a developer to the image carrier to visualize the electrostatic latent image;
A housing that contains the developer carrying member and that accommodates the developer supplied to the image carrier by the developer carrying member;
Pressing means for pressing the housing in a direction in which the developer carrier is pressed against the image carrier;
Separation means for moving the housing in a direction of separating the developer carrier from the image carrier;
An image forming apparatus comprising:
The housing includes end side surfaces that are erected in a direction perpendicular to the axial direction of the developer carrier from each end of the developer carrier.
Said end side comprises a projecting portion which projects outwardly along a direction parallel to the front Symbol axial direction,
The projecting part is an acted part on which the separating means acts,
Some of the working portion of the pressing means acts, the image forming apparatus characterized by being located on the side end surface and the same surface. A developer carrier that supplies a developer to the image carrier and visualizes the electrostatic latent image formed on the surface of the image carrier;
A developing unit comprising: the developer carrying member; and a housing for accommodating the developer supplied to the image carrier by the developer carrying member,
The housing includes end side surfaces that are erected in a direction perpendicular to the axial direction of the developer carrier from each end of the developer carrier.
Said end side comprises a projecting portion which projects outwardly along a direction parallel to the front Symbol axial direction,
The projecting portion is an actuated portion on which a separation means provided on the apparatus main body acts to move the housing in a direction of separating the developer carrier from the image carrier,
A part of the actuated portion on which the pressing means provided in the apparatus main body presses the housing in the direction in which the developer carrying body is pressed against the image carrying body is located on the same plane as the side end face. A developing unit characterized by that .

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