JP4794995B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, a printer, a scanner, or a multifunction machine having both functions.

  In image forming apparatuses such as copiers, facsimiles, printers, scanners, or multi-function machines having both of these functions, the photosensitive drum, charger, drum cleaning device, etc. The components are generally configured as a unit (image forming unit) as an integral unit (see Patent Document 1, etc.). In such an image forming apparatus, the image forming units are positioned and arranged with high accuracy.

The image forming unit and some of its components are detachable for maintenance and the like. In particular, when the charger integrated with the image forming unit is of a type having a contact type charging roller, the charger can be attached to and detached from the image forming unit frame to improve the recyclability of the charging roller. Various proposals have been made to facilitate it. For example, in Patent Document 2, the charger is attached to and removed from the image forming unit frame along the longitudinal direction of the photosensitive drum from the opening provided in the side wall of the image forming unit frame. To be able to do that.
Japanese Patent Laid-Open No. 2002-132000 JP 2003-208077 A

  However, these proposals are only intended to make it easy to attach and detach the charger to / from the image forming unit frame, with sufficient consideration given to labor savings and miniaturization of the device. That wasn't true. That is, even when only the charger is being maintained, once the entire image forming unit has been removed from the main body of the apparatus, the charger is removed from the image forming unit frame, and after the maintenance, the charger is placed inside the image forming unit frame. After mounting, the troublesome work of mounting the entire image forming unit on the apparatus main body is forced. In addition, the image forming unit must be handled with care so as not to touch the surface of the photosensitive drum, which is easily damaged, so a large handle or gripping part that can be seen at a glance on the exterior of the image forming unit frame. In some cases, the imaging unit cannot be downsized.

  In particular, in a tandem type full-color printer or the like, a plurality of image forming units corresponding to each color are arranged, so that the configuration of the apparatus is complicated, and maintenance work and downsizing of the apparatus are further required.

  The present invention has been made in view of such problems, and an object of the present invention is to facilitate the maintenance work of the image forming unit and the like and reduce the size of the apparatus.

The present invention has at least a photosensitive drum, and is detachably attached to the image forming unit frame body charger for charging the photosensitive drum to an image forming unit provided integrally with the image forming unit In an image forming apparatus that is detachably mounted between the first and second side plates of the apparatus main body, the image forming unit provided on the first side plate can be detachably attached to an opening. A process side plate that is attached and positions the image forming unit; a grip portion provided on the charger; and an opening portion that is provided on the process side plate and that the grip portion looks into from the inside of the apparatus main body. Only the charger can be attached to and detached from the apparatus main body while holding the gripping part from an opening provided in the process side plate with the image forming unit attached to the apparatus main body and attached to the first side plate. In addition, the process side plate is detached from the first side plate, and the image forming unit can be attached to and detached from the apparatus main body while holding the gripping portion in a state where the charger is attached to the image forming unit. And

  The charging part of the charger is integrally formed on one end side of the charging housing. The charging part can be slidably attached to and detached from the photosensitive drum in the axial direction. The image forming unit can be slidably attached to and detached from the apparatus main body in the axial direction of the photosensitive drum.

  And when the image forming unit is pulled out from the apparatus main body, there is provided a restricting means for restricting the image forming unit from dropping from the apparatus main body.

  Further, the image forming unit has a structure capable of holding the lower part of the image forming unit when the image forming unit is pulled out from the apparatus main body.

  According to the present invention, since the image forming unit having the photoconductor and the charger is mounted on the apparatus main body, the gripper provided on the charger is held and the charger can be attached and detached. Maintenance work of the charger is facilitated. In addition, in a state in which the charging unit provided in the charger fixes the charger to the image forming unit, the charging unit functions as a holding unit of the image forming unit, so that no extra member is required and the structure is compact. Further, when the image forming unit is pulled out in accordance with the grip portion, a restricting means is provided so that the lower part of the image forming unit can be held, so that the image forming unit can be attached and detached easily and safely.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing an image forming apparatus according to an embodiment of the present invention (in this embodiment, an electrophotographic tandem type full-color printer).

  The image forming apparatus includes an image forming unit 1M that forms a magenta image on the apparatus main body A, an image forming unit 1C that forms a cyan image, an image forming unit 1Y that forms a yellow image, and a black Four image forming units (image forming units) of the image forming unit 1Bk for forming a color image are provided, and these four image forming units 1M, 1C, 1Y, and 1Bk are arranged in a line at regular intervals. Has been.

  Photosensitive drums 2a, 2b, 2c, and 2d as image carriers are installed in the image forming units 1M, 1C, 1Y, and 1Bk, respectively. Around the photosensitive drums 2a, 2b, 2c, 2d, there are chargers 3a, 3b, 3c, 3d, developing units 4a, 4b, 4c, 4d as developing means, transfer rollers 5a, 5b, 5c, 5d, Drum cleaning devices 6a, 6b, 6c, and 6d are installed, respectively, and an optical unit (exposure unit) as an exposure unit is provided below the chargers 3a, 3b, 3c, and 3d and the developing units 4a, 4b, 4c, and 4d. Optical units) 7a, 7b, 7c, and 7d are installed. Each developing unit 4a, 4b, 4c, and 4d contains yellow toner, magenta toner, cyan toner, and black toner, respectively.

  Each of the photoconductor drums 2a, 2b, 2c, and 2d is a negatively charged OPC photoconductor having a photoconductive layer on an aluminum drum base, and is driven in the direction indicated by an arrow (counterclockwise) by a driving device (not shown). Are rotated at a predetermined process speed.

  The chargers 3a, 3b, 3c and 3d as charging means uniformly apply the surface of each photosensitive drum 2a, 2b, 2c and 2d to a predetermined negative potential by a charging bias applied from a charging bias power source (not shown). Charges up.

  The developing units 4a, 4b, 4c, and 4d develop toner images by attaching toners of respective colors to the electrostatic latent images formed on the photosensitive drums 2a, 2b, 2c, and 2d, respectively (visualization). To do. As a developing method using the developing units 4a, 4b, 4c, and 4d, for example, toner particles mixed with a magnetic carrier are used as a developer and conveyed by magnetic force, and the photosensitive drums 2a, 2b, 2c, and 2d are used. In contrast, a two-component contact development method in which development is performed in a contact state can be used.

  The transfer rollers 5a, 5b, 5c, and 5d as transfer means are each photosensitive via an endless belt-like intermediate transfer body (hereinafter referred to as an intermediate transfer belt) 8 at each primary transfer nip portion Ta, Tb, Tc, and Td. The body drums 2a, 2b, 2c and 2d are in contact. The intermediate transfer belt 8 is stretched between the drive roller 9, the secondary transfer counter roller 10, and the tension roller 11, and is rotated (moved) in the arrow direction (clockwise) by the drive of the drive roller 9. The intermediate transfer belt 8 is made of a dielectric resin such as a polycarbonate, a polyethylene terephthalate resin film, a polyvinylidene fluoride resin film, or the like.

  The secondary transfer counter roller 10 is in contact with the secondary transfer roller 12 via the intermediate transfer belt 8 to form a secondary transfer portion Te. The secondary transfer roller 12 is installed so as to be able to contact and separate from the intermediate transfer belt 8. In the vicinity of the tension roller 11 outside the intermediate transfer belt 8, a belt cleaning device 13 for removing and collecting the transfer residual toner remaining on the surface of the intermediate transfer belt 8 is installed. In the belt cleaning device 13, a cleaning roller 13 a is installed in contact with the intermediate transfer belt 8. A fixing device 14 having a fixing roller 14a and a pressure roller 14b is installed downstream of the secondary transfer portion Te in the transfer material conveyance direction.

  The drum cleaning devices 6a, 6b, 6c, and 6d remove and collect the transfer residual toner remaining on the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d by the cleaning roller.

  The optical units 7a, 7b, 7c, and 7d as exposure means receive laser light modulated in response to time-series electric digital pixel signals of image information inputted from a host computer (not shown), respectively, in a laser output section (not shown). The surface of each photosensitive drum 2a, 2b, 2c, 2d is scanned and exposed via a polygon mirror (not shown) that rotates at a high speed and is charged by each charger 3a, 3b, 3c, 3d. An electrostatic latent image of each color corresponding to the image information is formed on the surface of each of the photosensitive drums 2a, 2b, 2c, and 2d.

  The developing units 4a, 4b, 4c, and 4d of the image forming units 1M, 1C, 1Y, and 1Bk are configured by unitizing components such as developing rollers. Each developing unit 4a, 4b, 4c, 4d is detachably attached to the apparatus main body A.

  In addition, as shown in FIG. 2, the photosensitive drum 2a, the charger 3a, and the drum cleaning device 6a of each of the image forming units 1M, 1C, 1Y, and 1Bk (the image forming unit 1M in the figure) are integrally unitized. An image forming unit 30a is configured. The image forming unit 30a (the image forming units 30b, 30c, and 30d (see FIG. 4) of the other image forming units 1C, 1Y, and 1Bk) are also detachably attached to the apparatus main body A (image forming unit 30a). , 30b, 30c, and 30d will be described later in connection with the apparatus main body A).

  Next, an image forming operation by the above-described image forming apparatus will be described.

  When an image formation start signal is issued, the photosensitive drums 2a, 2b, 2c, and 2d of the image forming units 1M, 1C, 1Y, and 1Bk that are rotationally driven at a predetermined process speed are respectively charged with the chargers 3a, 3b, 3c and 3d are uniformly charged to negative polarity. Then, the optical units 7a, 7b, 7c, and 7d respectively convert the input color-separated image signals into optical signals at a laser output unit (not shown), and use laser beams that are converted optical signals. Each charged photosensitive drum 2a, 2b, 2c, 2d is scanned and exposed to form an electrostatic latent image.

  First, magenta toner is adhered to the electrostatic latent image formed on the photosensitive drum 2a by the developing unit 4a to which a developing bias having the same polarity as the charging polarity (negative polarity) of the photosensitive drum 2a is applied. The toner image is visualized. Meanwhile, the magenta toner image is rotated (moved) by the transfer roller 5a to which a primary transfer bias (opposite polarity (positive polarity) from the toner) is applied at the primary transfer portion Ta between the photosensitive drum 2a and the transfer roller 5a. Primary transfer is performed on the intermediate transfer belt 8.

  The intermediate transfer belt 8 onto which the magenta toner image has been transferred is rotated (moved) toward the image forming unit 1C. In the image forming unit 1C, the cyan toner image formed on the photosensitive drum 2b in the same manner as described above is superimposed on the magenta toner image on the intermediate transfer belt 8 and transferred by the primary transfer unit Tb. Is done.

  In the same manner, yellow and black toner images formed by the photosensitive drums 2c and 2d of the image forming units 1Y and 1Bk on the magenta and cyan toner images superimposed and transferred onto the intermediate transfer belt 8 in the same manner are respectively primary. A full color toner image is formed on the intermediate transfer belt 8 by sequentially superimposing at the transfer portions Tc and Td.

  At the time of the primary transfer described above, the primary transfer residual toner remaining on the photosensitive drums 2a, 2b, 2c, and 2d is removed and collected by the drum cleaning devices 6a, 6b, 6c, and 6d, respectively. Further, secondary transfer residual toner and the like remaining on the intermediate transfer belt 8 after the secondary transfer are removed and collected by the cleaning roller 13a of the belt cleaning device 13.

  When obtaining a single color image (for example, a monochrome image), a single color (for example, a monochrome image) is primarily transferred onto the intermediate transfer belt 8 from a specific image forming unit (for example, the image forming unit 1Bk). A monochromatic image can be obtained through a process similar to that for forming a full-color image.

  Next, the configuration of the image forming units 30a, 30b, 30c, and 30d will be described. Hereinafter, the image forming unit 30a will be described as an example, but the other image forming units 30b, 30c, and 30d are also the same, and thus description thereof will be omitted. FIG. 3 is an external perspective view of the image forming unit 30a.

  As shown in FIG. 3, the image forming unit 30a includes a photosensitive drum 2a, a charger 3a, and a drum cleaning device 6a (see FIG. 2). The photosensitive drum 2a is rotatably supported on the front wall and the rear wall of the image forming unit frame 31 via bearings 36 (only the front side is shown in FIG. 3). An opening 31a is provided in the front wall of the image forming unit frame 31 so as to penetrate below the photosensitive drum 2a. Between the front wall and the rear wall of the image forming unit frame 31, a charger accommodating portion 31b is formed as a space extending in the axial direction of the photosensitive drum 2a. The charger accommodating portion 31b is interposed through the opening 31a. The image forming unit frame 31 communicates with the outside. A pair of saddle-shaped guide rails 31c extending in the axial direction of the photosensitive drum 2a are integrally formed with the image forming unit frame 31 below the charger housing 31b. A bump 31d having an inclined surface is integrally formed at the rear end portion of the sliding surface of the guide rail 31c extending in the axial direction of the photosensitive drum 2a. The leading edge of the guide rail 31c extending in the axial direction of the photosensitive drum 2a constitutes an engaging protrusion 31e. On the front wall of the image forming unit frame 31, a boss 31f is provided on the left side of the opening 31a. An engaging portion 31g that extends in the width direction of the image forming unit frame 31 and protrudes downward with a predetermined thickness is formed at the rear end of the lower surface of the image forming unit frame 31.

  Reference numeral 34 in the drawing is a connecting pipe that connects the drum cleaning device 6a (see FIG. 2) and a toner cartridge (not shown) attached to a process side plate 40 (see FIG. 4) described later, and is provided inside this connecting pipe. The waste toner collected by the drum cleaning device 6a (see FIG. 2) is transported to the waste toner collecting portion in the toner cartridge through the connecting pipe by the transport mechanism.

  The charger 3 a can be attached to and detached from the image forming unit frame 31. Bearings (not shown) are disposed at both ends inside the charging housing 32, and a charging roller 33 is rotatably held by the bearings. Below the charging roller 33, a cleaning roller (not shown) around which a fur brush for rubbing and cleaning the surface of the charging roller 33 is disposed. The bearing of the charging roller 33 is urged upward by a compression spring (not shown) disposed therebelow. On the front wall of the charging housing 32, a grip portion 32 a that is held when the charger 3 a is attached to or detached from the image forming unit frame 31 or attached to or detached from the apparatus main body A of the image forming unit 30 a protrudes forward and is integrally formed. Further, projecting pieces 32b extending downward with a predetermined thickness are integrally formed on the front wall and the rear wall of the charging housing 32, respectively. A pair of left and right engaging grooves 32c are formed on both sides of the protruding pieces 32b. A projecting piece 32d extending to the left with a predetermined thickness is formed on the front wall of the charging housing 32. A screw hole 32e is provided through the projecting piece 32d.

  The charger 3 a is inserted as indicated by an arrow X through the opening 31 a in the front wall of the image forming unit frame 31. As the battery is further inserted, the lower surface of the charging housing 32 is guided along the guide rail 31c. Finally, the rear end portion of the charging housing 32 rides on the bump 31d and moves upward so that the charging roller 33 is exposed to light. It contacts the surface of the body drum 2a. Each of the pair of engaging protrusions 31e formed by the leading edge of the guide rail 31c is engaged with each of the pair of engaging grooves 32c provided on the protrusions 32b on the front wall and the rear wall of the charging housing 32. Positioning is performed. Finally, the screw 35 is fastened and fixed to the screw hole 32e of the protrusion 32d on the front wall of the charging housing 32 and the boss portion 31f of the image forming unit frame 31.

  Next, attachment of the image forming units 30a, 30b, 30c, and 30d and the developing units 4a, 4b, 4c, and 4d to the apparatus main body A will be described. FIG. 4 is a view for explaining the positional relationship between the process side plate and the first and second side plates of the image forming apparatus according to the embodiment of the present invention.

  As shown in FIG. 4, the image forming units 30a, 30b, 30c, 30d and the developing units 4a, 4b, between the first side plate 50 on the front side of the apparatus main body A and the second side plate 57 on the back side thereof. 4c and 4d are detachably held. The image forming units 30a, 30b, 30c, and 30d are sliding surfaces of a pair of guide rails 45 (see FIG. 6) arranged between the first side plate 50 and the second side plate 57 of the apparatus main body A. Is inserted from an opening 50a formed in the first side plate 50 so that each side edge portion of the lower surface of the image forming unit frame 31 extends along each of the first and second side plates 50, and the rear portion is a driving means (provided on the second side plate 57). (Not shown) and connected. Similarly, after the image forming units 30a, 30b, 30c, and 30d are mounted, the developing units 4a, 4b, 4c, and 4d are inserted in the positions immediately to the right of the image forming units 30a, 30b, 30c, and 30d. The first and second side plates 50 and 57 are positioned.

  After mounting the image forming units 30a, 30b, 30c, 30d and the developing units 4a, 4b, 4c, 4d, the positioning of the image forming units 30a, 30b, 30c, 30d and the toner cartridge (on the front side of the first side plate 50) A process side plate 40 having a function of mounting (not shown) is attached to the apparatus main body A so as to close the opening 50a. The process side plate 40 is removed when the image forming units 30a, 30b, 30c, and 30d or the developing units 4a, 4b, 4c, and 4d are replaced.

  As shown in FIG. 4, a toner cartridge (not shown) that stores magenta toner corresponding to the image forming unit 30a and the developing unit 4a of the image forming unit 1M is detachably mounted on the surface of the process side plate 40. Cartridge holder 42a, a toner cartridge (not shown) that stores cyan toner corresponding to the image forming unit 30b and the developing unit 4b of the image forming unit 1C, and a cartridge holder 42b in which the toner cartridge (not shown) is detachably mounted. Corresponding to the image forming unit 30d and the developing unit 4d of the image forming unit 1Bk, the cartridge holder 42c to which a toner cartridge (not shown) that accommodates yellow toner corresponding to the image forming unit 30c and the developing unit 4c is detachably mounted. Toner cartridge (not shown) that contains black toner There cartridge 42d holder is detachably mounted are arranged in a row at regular intervals. Each of the cartridge holders 42a, 42b, 42c, and 42d is swingably attached to the lower edge portion of the surface of the process side plate 40 with a hinge as a fulcrum.

  The positioning pin 43a and the engaging claw 44a are fixed to the right end portion of the back surface of the process side plate 40, and the same positioning pin 43b and the engaging claw 44b are also fixed to the left end portion of the back surface of the process side plate 40. On the other hand, the positioning holes 60a and 60b and the engagement holes 61a and 61b correspond to the positioning pins 43a and 43b and the engaging claws 44a and 44b on the left and right sides of the opening 50a of the first side plate 50, respectively. Is provided. As indicated by solid arrows in FIG. 4, the positioning pins 43a and 43b are inserted into the positioning holes 60a and 60b of the first side plate 50, and the engaging claws 44a and 44b are engaged with the process side plate 40 positioned. The process side plate 40 is securely held at an appropriate position of the first side plate 50 by engaging with the joint holes 61a and 61b.

  Further, holes 40a, 40b, 40c, and 40d in which the bearings 36 that hold the photosensitive drum shafts of the image forming units 30a, 30b, 30c, and 30d are fitted (or engaged) are provided on the back side of the process side plate 40. They are provided in a row at regular intervals. The holes 40a, 40b, 40c, 40d are accurately positioned with reference to the positioning pins 43a, 43b, and the positioning pins 43a, 43b arranged on the process side plate 40 are replaced with the positioning holes 60a of the first side plate 50. , 60b and the process side plate 40 is attached to the first side plate 50 so that the bearings 36 of the image forming units 30a, 30b, 30c, 30d are fitted into the holes 40a, 40b, 40c, 40d (or The image forming units 30a, 30b, 30c, and 30d are accurately positioned.

  Further, the process side plate 40 has an opening 41a for the end of the developing unit 4a, an opening 41b for the end of the image forming unit 30a and the developing unit 4b, an image forming unit 30b and a developing unit 4c. The opening 41c for the end portion, the opening 41d for the end portion of the image forming unit 30c and the developing unit 4d, and the opening portion 41e for the end portion of the image forming unit 30d are spaced apart from each other. It is provided in a row. By attaching the process side plate 40 to the first side plate 50, the image forming unit and the developing unit corresponding to each other through the opening 50a of the first side plate 50 and the openings 41a, 41b, 41c, 41d, 41e of the process side plate 40. The image forming units 1M, 1C, 1Y, and 1Bk corresponding to the toner cartridges (not shown) of cyan, magenta, yellow, and black that are mounted on the cartridge holders 42a, 42b, 42c, and 42d, respectively. A pair of the image forming unit and the developing unit can be connected.

  Next, removal of the image forming units 30a, 30b, 30c, and 30d from the apparatus main body A will be described with reference to FIGS. Hereinafter, the image forming unit 30d will be described as an example. However, since the other image forming units 30a, 30b, and 30c are the same, description thereof will be omitted.

  FIG. 5 is a perspective view showing a state where the charger 3d is removed from the apparatus main body A. FIG. When removing the charger 3d from the apparatus main body A, first, the toner cartridge (not shown) is removed, and the cartridge holder 42d is swung and tilted forward. Then, the screw 35 (see FIG. 6) that fixes the charger 3d to the image forming unit frame 31 is removed from the opening 41e of the process side plate 40. As a result, as indicated by the arrow Y in FIG. 5, it is possible to pull out only the charger 3d forward and remove it from the apparatus main body A with the image forming unit 30d attached to the apparatus main body A. Even if the rear end of the charger 3d exits from the apparatus main body A, that is, the opening 50a of the first side plate 50, the cartridge holder 42d exists in a tilted state, so that the risk of inadvertently dropping the charger 3d is prevented. The

  FIG. 6 is a perspective view showing how the image forming unit 30d is removed from the apparatus main body A. FIG. When the image forming unit 30d is taken out from the apparatus main body A, as shown in FIG. 6, the process side plate 40 is removed from the first side plate 50, and the developing unit 4d (see FIG. 3), the image forming unit 30d is pulled out with the gripping portion 32a of the charger 3d in a state where the charger 3d is fixed to the image forming unit frame 31 without removing the screw 35 of the charger 3d. .

  Further, immediately before the image forming unit 30d is taken out from the apparatus main body A, the lower rear end portion of the image forming unit frame 31 falls into a stepped portion 45a formed at the front end portion of the sliding surface of the guide rail 45, Since the locking portion 31g is locked to the lower edge portion of the opening 50a of the first side plate 50 and the drawing of the image forming unit 30d is restricted, the image forming unit 30d can be prevented from dropping. Further, since the image forming unit 30d has a structure in which the lower surface of the image forming unit frame 31 can be directly held by hand without touching the photosensitive drum 2a, it is possible to safely perform the subsequent removal operation. .

  Further, the image forming unit 30a can be attached and detached and the toner cartridge (not shown) can be replaced by opening the front cover (not shown) of the apparatus in front of the apparatus, and adjusting the optical units 7a, 7b, 7c and 7d. (For example, as shown in FIGS. 8 and 9, when the adjustment knob 71 is rotated with a screwdriver or the like from the openings 41a, 41b, 41c, 41d, 41e (see FIG. 4) of the process side plate 40). The adjustment cam 74 in contact with the mirror 73 is rotated by the worm gear 72 and the angle of the mirror 73 is changed so that the optical axis can be adjusted.

FIG. 1 is a schematic configuration diagram showing an image forming apparatus according to an embodiment of the present invention. These are the schematic block diagrams which show the image formation unit of the image forming apparatus which concerns on embodiment of this invention. FIG. 3 is a perspective view showing an image forming unit of the image forming apparatus according to the embodiment of the present invention with a charger removed. These are views for explaining the positional relationship between the process side plate and the first and second side plates of the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a perspective view showing a state where the charger is removed from the apparatus main body with the image forming unit of the image forming apparatus according to the embodiment of the present invention attached to the apparatus main body. These are perspective views which show a mode that the image forming unit of the image forming apparatus which concerns on embodiment of this invention is removed from an apparatus main body. These are sectional drawings which show a mode that the image formation unit of the image forming apparatus which concerns on embodiment of this invention is removed from an apparatus main body. These are perspective views showing an optical unit of the image forming apparatus according to the embodiment of the present invention. These are perspective views which show the optical axis adjustment part of the optical unit of the image forming apparatus which concerns on embodiment of this invention.

Explanation of symbols

1M, 1C, 1Y, 1Bk Image forming units 2a, 2b, 2c, 2d Photosensitive drums 3a, 3b, 3c, 3d Chargers 4a, 4b, 4c, 4d Developing units 5a, 5b, 5c, 5d Transfer rollers 6a, 6b , 6c, 6d Drum cleaning device 7a, 7b, 7c, 7d Optical unit 8 Intermediate transfer belt 9 Drive roller 10 Secondary transfer counter roller 11 Tension roller 12 Secondary transfer roller 13 Belt cleaning device 13a Cleaning roller 14 Fixing device 14a Fixing roller 14b Pressure roller 30a, 30b, 30c, 30d Image forming unit 31 Image forming unit frame 31a Opening 31b Charger housing 31c Guide rail 31d Bump 31e Engagement protrusion 31f Boss 31g Locking part 32 Charging housing 32a Holding part 32b Projection piece 32c Engagement groove 32d Projection piece 32e Screw hole 33 Charging roller 34 Connection pipe 35 Screw 36 Bearing 40 Process side plate 40a, 40b, 40c, 40d Hole 41a, 41b, 41c, 41d, 41e Opening 42a, 42b, 42c, 42d Cartridge holder 43a, 43b Positioning pins 44a, 44b Engaging claw 45 Guide rail 45a Stepped portion 50 First side plate 50a Opening portion 57 Second side plate 60a, 60b Positioning hole 61a, 61b Engaging hole 71 Adjustment knob 72 Warm gear 73 Mirror 74 Adjustment cam A Main unit

Claims (4)

At least a photosensitive drum, is detachably attached to the image forming unit frame body having an imaging unit that charger and is integrally provided with the charging said photosensitive drum, said image forming unit of the apparatus body In the image forming apparatus that is detachably mounted between the first and second side plates,
A process side plate that is detachably attached to an opening into which the image forming unit provided in the first side plate is inserted, and that positions the image forming unit; a grip portion provided in the charger; An opening provided on the process side plate and viewed from the inside of the apparatus main body,
The process side plate is attached to the first side plate, the gripping unit is held from an opening provided in the process side plate with the image forming unit attached to the apparatus main body, and only the charger is attached to the apparatus main body. The process side plate is detachable from the first side plate, and the image forming unit can be attached to and detached from the apparatus main body while holding the gripper with the charger mounted on the image forming unit. An image forming apparatus, comprising: The charging part of the charger is integrally formed on one end of the charging housing. The charging part can be slidably attached to and detached from the photosensitive drum in the axial direction. The image forming apparatus according to claim 1, wherein the image forming unit is slidably attached to and detached from the apparatus main body in the axial direction of the photosensitive drum. The image forming apparatus according to claim 2 , further comprising a restricting unit configured to restrict the image forming unit from dropping from the apparatus main body when the image forming unit is pulled out from the apparatus main body. When the image forming unit drawn out from the apparatus main body, an image forming apparatus according to any one of claims 1 to 3, characterized in that it has a structure capable of holding the lower portion of the image forming unit.

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