JP2001142274A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the positioning accuracy of a sub-unit for image forming with respect to a main body frame by a simple constitution and also to surely suppress the occurrence of color slippage by the simple constitution even though the sub-unit for image forming is constituted of a CRU which is exchangeable by a user specially in the case that an object is a tandem type image forming device. SOLUTION: Relating to the image forming device in which the sub-unit 2 for image forming is positioned and attached at/to the main body frame 1, a positioning part 3 by which the sub-unit 2 is positioned and supported is integrally formed into the main body frame 1. Also, relating to the image forming device in which plural sub-nits 2 consisting of an image carrier unit 2 (1) including an image carrier are positioned and attached to the main body frame 1, plural positioning parts 3 (concretely 3 (1)) by which the plural sub-units 2 consisting of the image carrier unit 2 (1) are positioned and supported are integrally formed into the main body frame 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a printer, and more particularly to an improvement in an image forming apparatus effective for a so-called tandem type in which a plurality of image carriers are arranged in parallel.

[0002]

2. Description of the Related Art As a conventional tandem type image forming apparatus, for example, a plurality of image forming units of yellow, magenta, cyan, and black (for example, an electrophotographic system is adopted)
Are arranged in parallel, and a belt conveying device that circulates and conveys the conveying belt by being wrapped around a plurality of tension rolls is disposed at a portion facing each image forming unit, and directly or on a recording material ( There has been known an apparatus in which toner images of a plurality of colors formed in each image forming unit are sequentially multiplex-transferred via a paper or an OHP sheet (see, for example, JP-A-6-110290).

This type of tandem type image forming apparatus is certainly advantageous in terms of speeding up, but on the other hand, each color component image formed by each image forming unit is transferred to the same image carrying position of the conveyor belt. Alternatively, since it is necessary to transfer images on the same recording material sequentially, if the parallelism between the respective color image forming units is not obtained, color shift of each color component image occurs, and registration of each color component image is performed. There is a technical problem that it is difficult to match.

In order to solve such a technical problem,
In a conventional tandem-type image forming apparatus, a supporting unit to which components (a latent image carrier, a charging charger, an exposing unit, a developing unit, and a transferring unit) are attached is provided for each recording device for recording each color component image. The support means is pivotally supported by two reference pins with respect to the main body frame, and one of the reference pins is provided with a position adjusting means capable of adjusting a recording device attached to the support means in a direction in which the recording apparatus can be brought into and away from each other. In order to prevent the occurrence of image misalignment and maintain the assemblability of each recording device (for example, Japanese Patent Application Laid-Open No. 64-8426).
No. 3) or a first support plate provided with a plurality of support means for supporting one axial end of at least one of the image carrier, the latent image forming means and the transfer means,
A second support plate provided with a plurality of support means for supporting the other end in the axial direction of the means, and the first and second support plates are attached to a main body frame which is juxtaposed to be separated from each other. So that the parallelism of the constituent members of each image forming means can be obtained very easily and reliably.
A technique (for example, see Japanese Patent Application Laid-Open No. 6-332270) has been proposed, which has good assemblability and enables good image formation without color shift.

[0005]

However, in the former prior art (for example, JP-A-64-84263), when assembling each recording device to the main body frame, the position adjusting operation by the position adjusting means must be performed. Therefore, it is difficult to match the parallelism of the constituent elements of each recording device,
Not only does it take a very long time, but also the parts that need to be replaced, such as the latent image carrier, need to be adjusted each time when they are replaced. Therefore, a CRU (abbreviation for Customer Replaceable Unit) cannot be used, which is very costly. There was a technical problem of becoming expensive. In the latter prior art (for example, JP-A-6-332270),
Although the position adjustment process as in the former prior art is unnecessary,
Since each image forming unit has a support plate, there are many members interposed in the relative positional relationship of each image forming unit, and the alignment between the image forming units cannot be performed due to the accumulated error between the support plates, and color shift occurs. The configuration was insufficient to suppress the problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above technical problem, and an image forming apparatus capable of improving the positioning accuracy of an image forming subunit with respect to a main body frame with a simple structure. To provide. Particularly, when the present invention is applied to a tandem-type image forming apparatus, even if the image forming sub-unit has a user-replaceable CRU configuration, the occurrence of color misregistration can be suppressed with a simple configuration. An image forming apparatus is provided.

[0007]

That is, as shown in FIG. 1, the present invention relates to an image forming apparatus in which an image forming sub-unit 2 is positioned and mounted on a main body frame 1; 2 is an image forming apparatus in which a positioning portion 3 for positioning and supporting is integrally formed.

In such technical means, the "body frame 1" may be a frame serving as a reference for positioning and supporting the subunit 2. Usually, a plurality of sheet metal members are fixed by welding or other means. It is composed of
The “subunit 2” is the image carrying unit 2
(1) Image forming sub-units such as a transfer unit 2 (2), a latent image forming unit 2 (3), a registration unit (not shown), a fixing unit (not shown), and a sensor unit (not shown) It includes a wide range of units. Further, the "positioning portion 3" may be a positioning hole, a positioning boss, a positioning groove, a positioning surface, or the like in an appropriate manner as long as the subunit 2 can be positioned and supported. However, it is necessary that the subunit 2 corresponding to the positioning section 3 be provided with a positioning section that engages with the positioning section 3. Or a part of the subunit 2 (for example, the image carrying unit 2
In the embodiment having the drum-shaped image carrier as (1), an outer diameter portion at the end of the image carrier and a bearing member for rotating and holding the outer diameter portion may be used as it is. You may. In FIG. 1, 3 (1) is an image carrying unit 2 (1).
3 (2) is a positioning unit of the transfer unit 2 (2), 3 (3) is a positioning unit of the latent image forming unit 2 (3), 3
(4) is the positioning part of the register roll unit not shown, 3 (5)
Indicates a positioning unit of the fixing unit (not shown), but these are merely examples, and not all of them are necessarily provided. Furthermore, the phrase "the positioning portion 3 is integrally formed" means that a structure for attaching a separate positioning member is excluded from the viewpoint of improving positioning accuracy.

In particular, the present invention is effective in a so-called tandem type image forming apparatus. In this case, a plurality of sub-units 2 comprising an image carrier unit 2 (1) in which a main body frame 1 includes an image carrier is provided. In an image forming apparatus to be positioned and mounted, a plurality of positioning portions 3 (specifically, 3 (1)) for positioning and supporting a subunit 2 including a plurality of image carrying units 2 (1) are integrally formed on a main body frame 1. What is necessary is just to form it.

The positioning section 3 (1) for positioning and supporting the subunit 2 composed of the image carrying unit 2 (1) may be appropriately selected, but the positioning accuracy can be increased.
In addition, from the viewpoint of easy positioning operation, the positioning portion 3 (1) of the image carrier unit 2 (1) includes the image carrier 2a.
It is preferable to include a substantially V-shaped V-shaped block for positioning and supporting at two points P1 and P2 a bearing member at which the outer diameter portion or the outer diameter portion is rotatably held. here,
The phrase “provided with a V-shaped block” means that as long as a V-shaped block (section) is provided, a notched groove configuration or a hole configuration may be employed. Further, the angle of the V-shaped portion of the “V-shaped block” is not limited to an acute angle, but may be a right angle or an obtuse angle. In this aspect, from the viewpoint of minimizing the play of the positioning of the image carrying unit 2 (1), a pressing means for pressing the image carrying unit 2 (1) toward the V-shaped block may be provided. .

Further, from the viewpoint of further improving the positioning accuracy of the subunit 2 comprising the image carrying unit 2 (1), the main frame 1 comprises the image carrying unit 2 (1) including the image carrier 2a. In an embodiment in which the positioning portion 3 on which the subunit 2 is positioned and supported is integrally formed, the positioning portion 3 (1) of the image bearing unit 2 (1) includes an outer diameter portion or an outer diameter of an end portion of the image bearing member 2a. A V-shaped block having a substantially V-shape for positioning and supporting a bearing member rotatably held at two points, and a position regulating portion for regulating an end position of the image carrier unit 2 (1). Is preferred. The position restricting section here is the image carrying unit 2
In the case of regulating the end position of (1), for example, a positioning projection is provided at the end of the image bearing unit 2 (1), and this is positioned on a position regulating surface (on a plane) provided on the main body frame 1 side. The main body frame 1 may be provided with a positioning projection, for example, and the end surface of the image carrying unit 2 (1) (not only a flat surface but also a curved surface) may be provided. May be selected as appropriate. According to this aspect, the image carrier unit 2 (1) can be positioned in the vertical plane direction (XY direction) by the V-shaped block, while the image carrier unit 2 (1) can be positioned in the axial direction (Z direction) by the position regulating portion. ).

As described above, the image carrying unit 2 (1) is
In the aspect in which the positioning is performed in the direction and the Z direction, in order to minimize the play of the positioning of the image carrier unit 2 (1), the pressing unit that presses the image carrier unit 2 (1) toward the V-shaped block and the position regulating unit is used. Is preferably provided. In such a mode, the pressing means includes a mode in which the V-shaped block positioning and the position regulating section positioning are separately provided, but from the viewpoint of simplifying the device configuration, a mode in which both are used. Is preferred. As an embodiment of the pressing means that combines the two, for example, the image carrying unit 2 (1)
Side is provided with an inclined portion that is inclined along the axial direction of the image carrier 2a, and at least a pressing body whose pressing direction is directed to the V-shaped block side is engaged with the inclined portion, and the V-shaped block and the position regulating portion are engaged. What is necessary is just to press the image carrying unit 2 (1) simultaneously. In this aspect, in order to keep the positioning error small, it is preferable to make the pressing point of the pressing means and the positioning point as close as possible.

Further, the V-shaped block constituting the positioning portion 3 (1) of the image carrier unit 2 (1) is opposed to the driving force acting in the radial direction of the image carrier 2a when the image carrier 2a is driven. It is preferable in terms of layout that the portion has a wall portion as one support point, and even when the image carrier 2a is driven,
It is possible to effectively avoid the situation where the image carrying unit 2 (1) is displaced.

A positioning unit 3 is provided on a main body frame 1 for positioning and supporting a subunit 2 comprising a transfer unit 2 (2) for transferring an image on an image carrier to a recording medium.
In an embodiment in which (specifically, 3 (2)) is integrally formed, the positioning section 3 (2) of the transfer unit 2 (2) is related to the positioning section provided on the transfer unit 2 (2) side. Anything that matches is acceptable. Here, “transfer unit 2 (2)” includes
The present invention is not limited to a belt-type transfer unit such as an intermediate transfer belt or a paper transport belt, but also includes a roll-type transfer unit having only a transfer roll. The “positioned portion on the transfer unit 2 (2) side” includes various modes such as a bearing of a belt passing roll, a positioning boss, a positioning hole, and a positioning notch.

Further, as a preferred embodiment of the positioning structure of the image carrier unit 2 (1) and the transfer unit 2 (2), the image carrier unit 2 including the image carrier 2a
(1) A positioning unit 3 (specifically, 3 (1), 3 (1), 3 (2)) for positioning and supporting a subunit 2 comprising a transfer unit 2 (2) for transferring an image on the image carrier 2a to a recording medium.
In the embodiment in which (2)) is integrally formed, the transfer unit 2 (2) is configured to be retractable from the positioning position of the main body frame 1, and the image is formed when the transfer unit 2 (2) is retracted to the retracted position. A pressing space for securing the separation space of the carrying unit 2 (1) from the positioning position, while pressing the image carrying unit 2 (1) toward the positioning unit when the transfer unit 2 (2) is set to the positioning position. There is an embodiment that includes means.

Further, the image carrier 2 is mounted on the main body frame 1.
In a mode in which a positioning unit 3 (specifically, 3 (3)) for positioning and supporting a sub-unit 2 composed of a latent image forming unit 2 (3) for writing an electrostatic latent image on a is integrally formed, Positioning section 3 (3) of latent image forming unit 2 (3)
May be any as long as it engages with the portion to be positioned provided on the latent image forming unit 2 (3) side. Here, the “latent image forming unit 2 (3)” includes an exposure unit, an ion current writing unit, and the like as long as it forms an electrostatic latent image.
Further, the “position to be positioned on the latent image forming unit 2 (3) side” includes various aspects such as positioning protrusions, positioning bosses, and positioning holes.

When the preferred embodiment of the structure of the body frame 1 is viewed from the manufacturing method side, the structure of the body frame 1 includes at least two sheet metal members spaced apart from each other and arranged side by side.
It is preferable that the positioning portions 3 of the subunit 2 are simultaneously processed in a state where the two sheet metal members are overlapped. Further, from a viewpoint of strength, a preferred embodiment of the main body frame 1 structure includes at least two sheet metal members that are arranged side by side at a distance from each other and in which the positioning portions 3 of the subunits 2 are formed. And a box-shaped frame. In this case, two sheet metal members may be added to the originally box-shaped frame, or a part of the box-shaped frame may be constituted by the two sheet metal members. Further, in order to simplify the structure of the main body frame 1, the main body frame 1 structure also serves as a unit frame of the latent image forming unit 2 (3) for writing an electrostatic latent image on the image carrier 2a. You may.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings. First Embodiment FIG. 2 is an explanatory view showing a first embodiment of a tandem image forming apparatus to which the present invention is applied. In the figure, a tandem image forming apparatus includes an image forming unit 22 (specifically, 22a to 22a) of four colors (black, yellow, magenta, and cyan in this embodiment) in a main body housing 21.
d) are arranged in a horizontal direction, and a transfer unit 23 including an intermediate transfer belt 230 circulated and conveyed along the arrangement direction of the image forming units 22 is disposed above the d).
A recording material supply cassette 24 for accommodating a recording material such as paper (not shown) is provided below the main body housing 21, and a recording material transporting a transport path of the recording material from the recording material supply cassette 24. The road 25 is arranged in the vertical direction.

In this embodiment, the image forming units 22 (22a to 22d) are arranged in order from the upstream side in the circulation direction of the intermediate transfer belt 230, for example, for black, yellow, magenta, and cyan (the arrangement is not limited to this. The toner image is formed in any order (not limited to the order), and includes each photoconductor unit 30, each developing unit 33, and one common exposure unit 40. Here, the photoconductor unit 30 includes, for example, a photoconductor drum 31, a charger (a charging roll in this example) 32 for pre-charging the photoconductor drum 31, and a cleaner 34 for removing residual toner on the photoconductor drum 31. Are integrated into a cartridge. The developing unit 33 develops the electrostatic latent image formed by exposure on the charged photosensitive drum 31 by the exposure unit 40 with a corresponding color toner (for example, negative polarity in the present embodiment). is there. Note that reference numeral 35 (35a
35d) to 35d) are toner cartridges for replenishing each developing unit 33 with each color component toner. On the other hand, the exposure unit 40 includes, for example, four semiconductor lasers (not shown), one polygon mirror 42,
An imaging lens (not shown) and a mirror (not shown) corresponding to each photoconductor unit 30 are stored, and light from a semiconductor laser for each color component is deflected and scanned by a polygon mirror 42, and the imaging lens, A light image is guided to a corresponding exposure point on the photosensitive drum 31 via a mirror.

In the present embodiment, the transfer unit 23 is, for example, one in which an intermediate transfer belt 230 is stretched between a pair of tension rolls (one of which is a drive roll) 231 and 232. A primary transfer device (primary transfer roll in this example) 51 is disposed on the back surface of the intermediate transfer belt 230 corresponding to the photosensitive drum 31 of the photoconductor drum 31, and a voltage having a polarity opposite to the charging polarity of the toner is applied to the primary transfer device 51. By doing so, the toner image on the photosensitive drum 31 is electrostatically transferred to the intermediate transfer belt 230 side. Further, a secondary transfer device 52 is provided at a position corresponding to the tension roll 232 on the downstream side of the most downstream image forming unit 22d of the intermediate transfer belt 230, and records a primary transfer image on the intermediate transfer belt 230. Secondary transfer (collective transfer) is performed on the material. In the present embodiment, the secondary transfer device 52 includes a secondary transfer roller 521 that is disposed in pressure contact with the toner image bearing surface of the intermediate transfer belt 230 and a secondary transfer roller that is disposed on the back surface of the intermediate transfer belt 230. 52
And a backup roll (also used as a stretching roll 232 in this example) that forms one counter electrode. For example, the secondary transfer roll 521 is grounded, and a bias having the same polarity as the charged polarity of the toner is applied to the backup roll (stretch roll 232). Further, a belt cleaner 53 is disposed on the upstream side of the uppermost-stream image forming unit 22a of the intermediate transfer belt 230 so as to remove residual toner on the intermediate transfer belt 230.

The recording material supply cassette 24 is provided with a take away roll 61 for picking up the recording material. Immediately after the take away roll 61, a feed roll 62 for feeding the recording material is provided. A registration roll (registration roll) 63 that supplies the recording material to the secondary transfer portion at a predetermined timing is provided in the recording material conveyance path 25 located immediately before the next transfer portion. Reference numeral 64 denotes a feed roll for feeding a recording material for manual feeding. On the other hand, a fixing device 66 is provided in the recording material conveying path 25 located downstream of the secondary transfer portion, and a discharge roll 67 for discharging the recording material is provided downstream of the fixing device 66. The discharged recording material is stored in a storage tray 68 formed on the upper part of the housing 21.

Further, in this embodiment, a manual feeder (MSI) 71 is provided on the side of the main body housing 21, and the recording material on the manual feeder 71 is a take away roll 72 and a feed roll 64. At the recording material transport path 25. Furthermore, the two-sided recording unit 7 is provided in the main body housing 21.
The double-sided recording unit 73 is provided with
When the duplex mode in which image recording is performed on both sides of the recording material is selected, the recording material on which single-side recording has been performed is reversed by the discharge roll 67, and is taken in the inside by the guide roll 74 before the entrance, and the appropriate number of transport rolls 77 Internal recording material return transport path 76
The recording material is conveyed along the sheet and supplied again to the registration roll 63 side.

A drive system of the photosensitive drum used in the tandem type image forming apparatus according to the present embodiment will be described. This drive system, as shown in FIG.
Having a single drive motor 120 (fixed installation in this example),
A worm shaft (rotation transmission shaft) 122 is coaxially driven and connected to a drive shaft 120a of the drive motor 120 via a flexible coupling 121, and each image forming unit 22 (22a to 22a) of the worm shaft 122 is connected.
A worm gear 125 (specifically, 125a to 125d) is attached to a portion corresponding to the photoconductor drum 31 of d), while a worm wheel 126 (specifically, 126a to 126d) is attached to one end of each of the photoconductor drums 31. 126d)
Are mounted coaxially so that each worm wheel 126 and each worm gear 125 mesh with each other. In this drive system, the worm shaft 122
Is divided into a first split shaft 131 corresponding to the first and second image forming units 22a and 22b, and a second split shaft 132 corresponding to the third and fourth image forming units 22c and 22d. The divided shafts 131 and 132 are connected by a flexible coupling 135. And
Each of the divided shaft members 131 and 132 is a pair of bearings 14.
1, 142 or 143, 144, and one bearing 1 of the first split shaft 131.
Between the worm gear 41 and the worm gear 125a
47 are interposed.

Next, the operation of the image forming apparatus according to this embodiment will be described. 2 and 3, when a start switch (not shown) is turned on, the drive motor 12
0 rotates, and the driving force is transmitted to the worm shaft 122 via the flexible coupling 121. At this time, although the worm shaft 122 is divided into a plurality of divided shaft members 131 and 132, since the worm shaft 122 is connected by the flexible coupling 135, the driving force from the drive motor 120 is transmitted to the first divided shaft member 131. And, it is transmitted to the second split shaft 132 via the flexible coupling 135.
Therefore, the worm shaft 122 is driven to rotate integrally. As a result, the worm gear 125 provided coaxially with the worm shaft 122 rotates, and the worm wheel 126 meshing with the worm gear 125 rotates, so that each of the photosensitive drums 31 of each of the image forming units 22 (22a to 22d) is driven. Can be

Each color component toner image is formed on the photosensitive drum 31 driven in this manner, and each color component toner image on each photosensitive drum 31 is transferred by the primary transfer unit 51 to the intermediate transfer belt. The multiple transfer toner images on the intermediate transfer belt 230 are sequentially transferred onto the recording material by the transfer operation of the secondary transfer device 52. Thereafter, the recording material to which the multiple transfer toner image has been transferred passes through the fixing device 66 and is discharged to the storage tray 68.

In particular, in the present embodiment, as shown in FIGS. 4 to 8, the photosensitive unit 30 and the transfer unit 2
The exposure unit 3 and the exposure unit 40 are directly positioned on the main body frame 200 constituting the machine frame of the main body housing 21. FIG. 4 shows a main body frame structure used in the present embodiment. In FIG.
00 has a base frame 201 serving as a bottom plate, and a pair of main frames 2 before and after the base frame 201.
02 and 203 are separated from each other, and an appropriate number (two in this example) of support frames 204 and 205 are erected between the main frames 202 and 203 to form a base frame 201 and main frames 202 and 203. And the support frames 204 and 205 constitute a box-shaped frame having high strength.

In this embodiment, the main frame 2
Positioning portions 210 for positioning the photosensitive drums 31 (only the photosensitive drums 31 are shown in FIG. 5) of the four photosensitive units 30 are formed on the upper edges of the photosensitive members 02 and 203. As shown in FIGS. 4 to 6, the positioning portion 210 is used for positioning the photosensitive drum 31 in the vertical plane direction (XY directions), and for example, the outer diameter end of the photosensitive drum 31 or a bearing 311. (In this example, bearing 311)
Is formed by a notched groove provided with a substantially V-shaped V-shaped block 211 supported at two points P1 and P2. still,
Reference numeral 312 denotes a drive gear of the photosensitive drum 31. Here, one point P1 of the V-shaped block 211 is
It is provided facing the direction of the driving force acting in the radial direction of the photosensitive drum 31 during driving (indicated by the arrow in FIG. 6).

As shown in FIGS. 4 and 7, a transfer unit 2 is provided on the upper edges of the main frames 202 and 203.
Three positioning portions 221 and 222 are formed. In the present embodiment, the transfer unit 23 includes the intermediate transfer belt 2
30 has a pair of unit frames 233 laid over the stretching rolls 231, 232, and positioning legs which are attached to the both-end bearings 234 of the stretching roll 232 and the pair of unit frames 233 and project downward. 235 is provided as a portion to be positioned. Reference numeral 239 denotes a drive motor for driving the intermediate transfer belt 230. Therefore, in the present embodiment, the positioning portion 221 is configured as a positioning groove in which the bearing 234 of the tension roll 232 of the transfer unit 23 is engaged, while the positioning portion 222 is used for positioning the transfer unit 23. It is configured as a positioning surface on which the leg 235 is placed.

Further, in the present embodiment, as shown in FIGS. 4, 6 and 7, the transfer unit 23 is configured so as to be able to retract vertically or pivotally with respect to the main body frame 200. On both outer surfaces of the unit frame 233, pressing members 236 for pressing the respective photosensitive drums 31 are respectively provided. Here, as shown in FIG. 6, for example, the pressing member 236 is pressed in the direction to be pressed by the spring 237 (specifically, the supporting points P1 and P2 of the V-shaped block 211).
The pressing rod 238 is urged in a direction of pressing the photosensitive drum 31 toward the photosensitive drum 31), and is in contact with, for example, a part of a holder 322 that holds a bearing 311 of the photosensitive drum 31. However, a part of the bearing 311 may of course be directly contacted. And
When replacing (removing) the photoconductor unit 30, for example, by operating a unit setting mechanism (not shown),
After the transfer unit 23 is retracted from the main frame 200 from the mounting position shown by the solid line in FIG. 6 to the retracted position shown by the imaginary line, the photoconductor unit 30 is taken out. The photoreceptor unit 30 and the transfer unit 23 are previously supported by the setting mechanism, and by operating the unit setting mechanism, the transfer unit 23 is latched at the mounting position of the main body frame 200 (corresponding to positioning the transfer unit 23). The photosensitive drum 31 is pressed against the V-shaped block 211 of the main body frame 200 by a pressing member 236 provided in the transfer unit 23.

Further, positioning portions 241 to 243 of the exposure unit 40 are formed on the main frames 202 and 203, as shown in FIGS. In the present embodiment, the exposure unit 40 has a substantially box-shaped unit case 41, and a front portion (a case portion located on a side facing the main frame 202) of the unit case 41 projects forward. Positioning boss 4
02 is formed as a portion to be positioned, while a flange portion 403 projecting at least laterally is formed on a rear portion of the unit case 41, and a pair of positioning bosses 404, 405 projecting forward from the flange portion 403. Is formed as a portion to be positioned. The second main frame 203 has a rectangular insertion opening 203a into which the exposure unit 40 is inserted. When the exposure unit 40 is inserted through the insertion opening 203a, the unit of the exposure unit 40 is opened. The front part of the case 41 contacts the inside of the first main frame 202, and the flange part 4 of the rear part of the unit case 41 is formed.
03 is an insertion opening 203a of the second main frame 203.
It comes into contact with the outer edge side. Therefore, in the present embodiment, the positioning portion 241 is provided on the first main frame 2.
02 is formed as a positioning hole into which the positioning boss 402 of the exposure unit 40 fits.
On the other hand, the positioning portions 242 and 243 are formed at the edge of the insertion opening 203a of the second main frame 203, and are configured as positioning holes into which the positioning bosses 404 and 405 of the exposure unit 40 fit. In FIG. 8, reference numeral 250 denotes a mounting hole for mounting the exposure unit 40 with a fastener such as a screw. In the present embodiment,
Although one common exposure unit 40 is used, in a mode in which an exposure unit is individually provided for each image forming unit 22, a positioning structure that positions each individual exposure unit may be used.

In this embodiment, as shown in FIG. 4, of the positioning portions 210, 221-222, 241-243 formed on the main frames 202, 203, the positioning portions 210, 221-222, 241-243 are symmetrical with respect to the main frames 202, 203. Since the positioning portions 210, 221 and 222 formed at the same time are processed simultaneously with the two main frames 202 and 203 being superposed, the positional accuracy between them is extremely high. Note that the positioning portions 241 to 243 formed asymmetrically with respect to the main frames 202 and 203 may be individually processed. In FIG. 4, reference numeral 251 denotes an opening formed in the main frame 203 to escape a protruding portion (for example, a recovery path for collecting waste developer) provided at an end of the developing unit 33 on the main frame 203 side. is there.

Here, the performance of the image forming apparatus according to the present embodiment will be described. First, in the present embodiment, the photoconductor unit 3 is attached to the main body frame 200 of the image forming apparatus.
Since the positioning units 210, 221-222, 241-243 of the transfer unit 23 and the exposure unit 40 are integrally formed, there is no member interposed in the mutual positional relationship between the units 30, 23, and 40, so that it is simple. With the configuration, the units 30, 23, and 40 are accurately positioned.

In the present embodiment, the main body frame 2
00, each of the positioning units 210, 221-222, 2
The alignment of the main frames 202 and 203, which are two sheet metal members on which 41 to 243 are formed, is broken and the absolute position of each photoconductor unit 30 (specifically, 30 (1) to 30 (4)) Is the ideal position (for example, horizontal position in the figure)
9A, the deviation of the relative positional relationship such as the degree of parallelism between the respective photoconductor units 30 is very small, and the parallelism of the photoconductor drums 31 of the respective photoconductor units 30 is small as shown in FIG. The degree (the chain line in the figure indicates the axis of the photosensitive drum 31) is maintained. Therefore, each of the exposure beams Bm (Bm (1) to Bm (4)) from the exposure unit 40 and the photosensitive drum 3 of each of the photosensitive unit 30 (30 (1) to 30 (4))
The relative positional relationship with each other coincides with each other. For example, the color misregistration of each color component image can be performed without providing a mechanism for correcting a skew caused by the misalignment of the parallelism between the photosensitive drum 31 and the exposure unit 40. Does not occur. In this regard, if the image quality was examined in a comparative mode in which a support member or the like was interposed between each unit 30, 23, 40 and the main body frame 200, as shown in FIG. Since there is a concern that the parallelism of the photoconductor drums 31 of the photoconductor units 30 (30 (1) to 30 (4)) may be shifted, each of the exposure beams Bm (Bm (1) to Bm) from the exposure unit 40 may be used.
(4)) and each photoconductor unit 30 (30 (1) to 30 (4))
Relative positional relationship with the photosensitive drum 31 is shifted,
It has been confirmed that there is a concern that color shift of each color component image may occur.

Further, in the present embodiment, the outer diameter end of the photoconductor drum 31 of the photoconductor unit 30 or a member for holding the outer diameter end (the bearing 311 in this example) is attached to the main body frame 200.
Is positioned on the positioning section 210 having the V-shaped block 211, so that even in the photoreceptor unit 30 having the CRU configuration, the positioning accuracy is good with repeated replacement, and the occurrence of color misregistration can be prevented with a simple configuration. Can be. Also, the positioning unit 2 having the V-shaped block 211
10 has a configuration in which a wall serving as one support point is provided in the direction in which the driving force at the time of driving the photoconductor drum 31 is applied. Therefore, even if the photoconductor drum 31 is driven, there is little concern that the positioning accuracy will deteriorate. In particular, in the present embodiment, the pressing member 23
Since the photosensitive drum 31 is pressed toward the V-shaped block 211 of the positioning section 210 in Step 6, the positioning accuracy of the photosensitive drum 31 is always kept good.

The embodiments of the present invention are not limited to those described above, and the design may be appropriately changed as exemplified below. As a positioning structure of the transfer unit 23, for example, as shown in FIG. 10, unlike the above-described embodiment, a positioning boss 260 and a positioning leg 235 are provided on the unit frame 233, and these are used as positioning portions to position the main body frame 200. Part 221,
The position may be set to 222.

As a positioning structure for the exposure unit 40, for example, as shown in FIGS.
(The support frame 204 of the embodiment of FIG. 4).
The exposure unit 40 may be inserted and positioned through the insertion opening 270. In this case, as the exposure unit 40, a positioning projection 406 is formed on the left side portion of the unit case 41 in the drawing, and positioning bosses 407 projecting outward are respectively provided on right side edges of the front and rear portions of the unit case 41 in the drawing. , 40
8 and these are used as positioning portions. On the other hand, positioning holes 281 are formed in the support frame 205 as positioning portions into which the positioning projections 406 are inserted, and the right side of the main frames 202 and 203 in FIG. Positioning U-shaped holes 282 and 283 are formed at the edges as positioning portions to which the positioning bosses 407 and 408 fit. In the present embodiment, as shown in FIG. 12A, the width dimension of the positioning projection 406 is
1 is set to be narrower than the longitudinal dimension, so that the positioning projection 406 easily enters the positioning elongated hole 281. Then, in order to position the exposure unit 40, FIG.
As shown in (a), the positioning projection 406 is inserted into the positioning elongated hole 281, and in this state, the positioning holder 28 previously attached to the support frame 205.
At 5, the positioning projection 406 is pressed against and held against the lower edge of the positioning elongated hole 281, and the positioning bosses 407 and 408 are engaged with the positioning U-shaped holes 282 and 283, as shown in FIG. Main frame 2
The positioning bosses 407 and 408 may be pressed and held against the edges of the positioning U-shaped holes 282 and 283 by the positioning holders 286 and 287 previously attached to the 02 and 203. Reference numerals 288 and 289 denote the exposure unit 4
0 is a mounting hole for mounting 0 with a fastener such as a screw.

Further, with respect to the structure of the main body frame 200, for example, in a mode in which a notch groove is formed in the upper edge of the main frames 202 and 203 as the positioning portion 210 of the photoconductor unit 30, the rigidity of the main frames 202 and 203 is reduced. In other words, the mainframe 202,
In the sense of reinforcing the rigidity of 203, as shown in FIG.
For example, a rigid reinforcing portion 290 may be provided in a part or all (in the present example, two inside) of the positioning portion 210 including four notched grooves for each of the main frames 202 and 203. Here, as the rigidity reinforcing portion 290, for example, one in which an E-shaped connecting portion is integrally provided above the two positioning portions 210 and the connecting portion is bent.

Further, as the structure of the main body frame 200, in the above-described embodiment, each of the frames 201 to 20 is used.
5, a box-shaped frame is formed. For example, a box-shaped frame is already constructed without the main frames 202 and 203, and the main frames 202 and 2 are added thereto.
03 may be added, and in order to simplify the structure of the main body frame 200, the unit case 41 of the exposure unit 40 may be replaced with, for example, the main frame 202, as shown in FIG. 203 may also be used.

In this embodiment, the positioning structure for the photosensitive unit 30, the transfer unit 23, and the exposure unit 40 is shown. However, the present invention is not limited to this. For example, as shown in FIG. 200
In addition, positioning parts (for example, constituted by positioning holes) 301 and 302 for positioning both ends of the resist roll 63 and the heat roll of the fixing device 66 are provided, or an image density and a pixel position on the intermediate transfer belt 230 are detected. A positioning portion 303 for positioning a bracket (not shown) of the sensor unit 310 may be provided. For example, if the sensor unit 310 is directly positioned on the main body frame 200, the correlation between the sensor unit 310 and the intermediate transfer belt 230 can be easily maintained with high accuracy, and the detection by the sensor unit 310 is correspondingly performed. The accuracy is improved.

Second Embodiment FIG. 16 shows a main part of an image forming apparatus according to a second embodiment of the present invention. In the present embodiment, the basic configuration of the image forming apparatus is substantially the same as that of the first embodiment, but the positioning structure of the subunit such as the photoconductor unit 30 is different from that of the first embodiment. That is, in the first embodiment, for example, the positioning structure of the photoconductor unit 30 is such that the positioning unit 210 having the V-shaped block 211 formed on the main body frame 200 (the main frames 202 and 203) has a vertical structure. Since the photoconductor unit 30 is positioned in the plane direction (XY direction), the positioning of the photoconductor unit 30 in the axial direction (Z direction) is performed by a separate positioning mechanism [for example, at the stage of positioning and mounting the photoconductor unit 30 on the positioning unit 210. A mechanism for restricting the position of the photoconductor unit 30 in the axial direction (Z direction) is required, but in the present embodiment, for example, the positioning structure of the photoconductor unit 30 is, as shown in FIG. 30 can be simultaneously positioned in the vertical direction (XY direction) and the axial direction (Z direction). As a positioning portion 210 provided in the 200, the photoconductor unit 3
A V-shaped block 211 similar to that of the first embodiment for positioning in the vertical plane direction (XY directions) of 0, and an end of the photoconductor unit 30 for positioning in the axial direction (Z direction) of the photoconductor unit 30. And a position restricting surface 212 for restricting the position. Note that components similar to those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and detailed description thereof is omitted here.

In the present embodiment, the body frame 20
0 is, for example, each frame 201 substantially the same as in the first embodiment.
To 205 (see FIG. 4), unlike the first embodiment, an outer frame 206 is further provided outside the main frame 202 as shown in FIG.
A V-shaped block 211 is formed integrally with the main frames 202 and 203, and a position regulating surface 212 is formed integrally with a part of the inner surface of the outer frame 206. FIG. 17 shows details of the photoconductor unit 30 used in the present embodiment. In the figure, the photoconductor unit 30 has a photoconductor drum 31, a charger (a charging roll in this example) 32 and a cleaner 34 incorporated in a CRU housing 320, as in the first embodiment. The configuration of the body drum 31 is partially different from that of the first embodiment. That is, the photosensitive drum 31
As shown in FIG. 18, bearings (bearings) 311 are fitted to both ends of the outer diameter end of the drum main body 31 a, and a driving gear 312 is further attached to one end of the outer diameter end (in this example, the main frame 202 side). 19 and 20, an end cap 313 is press-fitted to the end of the drum body 31a on the side of the drive gear 312 as shown in FIGS. 19 and 20, and approximately at the center of the end cap 313. The positioning projection 314 is formed, for example, integrally.

Further, the CRU housing 320 is the same as that shown in FIG.
As shown in FIG. 19, a substantially U-shaped bearing holding portion 321 for receiving both end bearings 311 of the photosensitive drum 31 is provided, and a holder 322 is detachably attached to the opening of the bearing holding portion 321. By attaching, the photosensitive drum 3
The outer case portion of the one end bearing 311 is fixed by interference fit. As shown in FIGS. 19 and 20, for example, the holder 322 used in the present embodiment has a substantially bow-shaped holder main body 323, and claw portions project outward and downward on both ends of the holder main body 323. A pair of locking claws 324, 32 slightly elastically deformed toward
5 are integrally provided so that the locking claws 324 and 325 are locked in locking holes 326 and 327 formed in the bearing holding portion 321 of the CRU housing 320. The mounting structure of the holder 322 is not limited to this, and one of the mounting structures is a locking structure between a locking claw and a locking hole, and the other is a locking structure using a fastener such as a screw. You can select it as appropriate. Further, a mountain-shaped inclined portion 328 that is inclined along the axial direction of the photosensitive drum 31 is formed integrally with a part of the top surface of the holder main body 323, and the inclined portion 328 has at least a pressing portion to be described later. A pressing slope 329 for contacting the member 236 is provided. It should be noted that in FIGS.
Reference numeral 0 denotes a drive transmission gear that meshes with the drive gear 312 of the photosensitive drum 31 and transmits a driving force to the waste toner conveying auger in the cleaner 34. Reference numeral 331 denotes a positioning opening formed in a part of the bearing holding portion 321. , And the support points P1 and P2 of the V-shaped block 211 directly contact the outer case portion of the bearing 311.

The transfer unit 23 has a pressing member 236 which operates in substantially the same manner as in the first embodiment.
The specific configuration of this is different from the first embodiment.
That is, in the present embodiment, the pressing member 236 is
As shown in FIGS. 16, 21 and 22, the transfer unit 23 is attached to both inner side surfaces of the unit frame 233, for example, a substantially central portion of a substantially V-shaped swing arm 360 bent at an obtuse angle. The rotation stud 361a is fixedly provided on the unit frame 233 in this example, and the rotation stud 361a is inserted into the rotation center hole of the swing arm 360.
An E-ring 361b for retaining is locked at the tip of the rotating stud 361a, and the rotating stud 361a is rotatable in a state where the swing arm 360 is prevented from falling off). A pressing roll 36 is provided at the tip of 360.
2 and an urging spring 363 is interposed between the base end of the swing arm 360 and the unit frame 233, and the urging force of the urging spring 363 causes the pressing roll 362 to move in the inclined portion 328 of the holder 322. It is designed to urge toward the pressing slope 329 side. 21 and 22, reference numeral 364 denotes an arm rotation stopper for stopping the rotation of the swing arm 360.

In this embodiment, the pressing roll 362 constituting the pressing member 236 comes into contact with the pressing slope 329 of the inclined portion 328 of the holder 322 from a substantially vertical direction against the urging force of the urging spring 363, and Component force is V
It acts on the character block 211 side and the position regulating surface 212 side in the direction of pressing the photoconductor unit 30 respectively. In the present embodiment, the pressing rod 238 as in the first embodiment may be used as the pressing member 236, but the mode (the swing arm 360 + the pressing roll 362) as in the present example is more suitable for pressing. This is preferable in that the pressing direction against the slope 329 can be accurately determined.

Next, the positioning performance of the photosensitive unit 30 of the image forming apparatus according to this embodiment will be described.
In other words, when the photoconductor unit 30 is positioned and mounted, as shown in FIG. 23, for example, the photoconductor unit 30 and the transfer unit 23 are previously supported by a unit set mechanism (not shown), and the unit set mechanism is operated. The photosensitive unit 30 and the transfer unit 23 may be moved to the mounting position of the main body frame 200. still,
In FIG. 23, the main frame 203 (see FIG. 16) located on the near side is omitted. At this time, when the transfer unit 23 is latched at the mounting position of the main body frame 200 (corresponding to positioning the transfer unit 23), the pressing member 236 provided on the transfer unit 23 is provided.
Is pressed against the urging force of the urging spring 363, as shown in FIGS. 23 and 24 (the support structure of the pressing member 236 is omitted).
Swings about the pivot 361, and the pressing roll 362 provided at the tip of the swing arm 360 abuts the pressing slope 329 of the inclined portion 328 of the holder 322 from a substantially vertical direction.

Then, the pressing force from the pressing roll 362 acts as a component force (A, B) on the inner side in the radial direction and the outer side in the axial direction of the photosensitive drum 31 (in this example, on the side of the positioning protrusion 314 of the photosensitive drum 31). The photoconductor unit 30
Is pressed toward the V-shaped block 211 by the radially inward force of the photosensitive drum 31 and simultaneously toward the position regulating surface 212 by the axially outward force of the photosensitive drum 31. In this state, the V-shaped block 211 positions and supports the bearing 311 in the vertical direction (XY directions), and the position regulating surface 212 positions and supports the positioning protrusion 314 in the axial direction (Z direction). The body unit 30 is simultaneously positioned with respect to the main body frame 200 not only in a vertical plane direction (XY directions) but also in an axial direction (Z direction).

In particular, in the present embodiment, one pressing member 236 is provided not only in the vicinity of the position regulating surface 212 but also in the V-shaped block 211, so that the pressing member 236 is also provided in the axial direction of the photosensitive unit 30. 236 and the positioning point are arranged close to each other, and accordingly, C
The influence of the deformation of the RU housing 320 in the axial direction is small, and the positioning accuracy of the photoreceptor unit 30 in the axial direction is maintained as well as in the vertical direction. In the present embodiment, the aspect in which the vertical direction (XY direction) and the axial direction (Z direction) are simultaneously positioned has been described by taking the photoconductor unit 30 as an example, but the present invention is not limited to this. Other subunits may be provided with the same mode as in the present embodiment. Further, it is needless to say that the same design change as in the first embodiment may be made for each component of the present embodiment.

[0048]

As described above, according to the present invention, since the positioning portion of the image forming subunit is formed integrally with the main body frame, the image forming subunit for the main body frame can be formed with a simple structure. The positioning accuracy of the unit can be improved. In particular, since the present invention can improve the positioning accuracy of the subunit with respect to the main body frame, when the tandem image forming apparatus is targeted, the subunit for image formation has a user-replaceable CRU configuration. However, the occurrence of color misregistration can be reliably suppressed with a simple configuration.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating an outline of an image forming apparatus according to the present invention.

FIG. 2 is an explanatory diagram illustrating an overall configuration of an image forming apparatus according to a first embodiment of the present invention;

FIG. 3 is an explanatory diagram showing a drive system of a photosensitive drum according to the embodiment.

FIG. 4 is an explanatory view showing a main body frame structure and a positioning part structure of each unit used in the present embodiment.

FIG. 5 is an explanatory view showing a positioning structure of a photoconductor unit.

FIG. 6 is an explanatory view of a main part showing a positioning state of a photoconductor unit.

FIG. 7 is an explanatory diagram illustrating a positioning structure of a transfer unit.

FIG. 8 is an explanatory diagram showing a positioning structure of an exposure unit.

FIG. 9A is an explanatory diagram showing the image quality of the image forming apparatus according to the present embodiment, and FIG. 9B is an explanatory diagram showing the image quality of the image forming device according to the comparative embodiment.

FIG. 10 is an explanatory view showing another example of the positioning structure of the transfer unit.

FIG. 11 is an explanatory view showing another example of the positioning structure of the exposure unit.

12 (a) and (b) are explanatory views showing the positioning state of portions A and B in FIG.

FIG. 13 is an explanatory view showing another example of the main body frame structure.

FIG. 14 is an explanatory view showing still another example of the main body frame structure.

FIG. 15 is an explanatory diagram showing a positioning structure of another subunit.

FIG. 16 is an essential part explanatory view showing Embodiment 2 of the image forming apparatus to which the present invention has been applied.

FIG. 17 is an explanatory perspective view showing a photoconductor unit used in the second embodiment.

FIG. 18 is an explanatory diagram illustrating a configuration of a photoconductor drum incorporated in a photoconductor unit used in the second embodiment.

FIG. 19 is an explanatory view showing a photosensitive drum support structure of a photosensitive unit used in the second embodiment.

20 is a view as viewed in the direction of the arrow XX in FIG. 19;

FIG. 21 is an explanatory diagram showing details of an XXI section in FIG. 16;

FIG. 22 is an explanatory diagram showing details of an XXII section in FIG. 16;

FIG. 23 is an explanatory diagram showing a positioning state of a photoconductor unit used in the second embodiment.

FIG. 24 is an explanatory diagram showing details of an XXIV section in FIG. 23;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Body frame, 2 (2 (1) -2 (3)) ... Subunit, 2a ... Image carrier, 3 (3 (1) -3 (5)) ... Positioning part

Continuing on the front page (72) Inventor Atsuyuki Kitamura 2274 Hongo, Ebina-shi, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Sakurako 2274 Hongo, Ebina-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd. F-term (reference) 2H030 AA06 AA07 AB02 BB02 BB10 BB42 BB46 BB54 2H071 AA27 BA05 BA13 BA16 BA20 BA22 BA27 BA29 DA02 DA08 DA09 DA12 DA15

Claims (14)

[Claims] An image forming apparatus for positioning and mounting an image forming sub-unit on a main body frame, wherein a positioning portion for positioning and supporting the sub-unit is integrally formed on the main body frame. apparatus. 2. An image forming apparatus in which a plurality of sub-units composed of image bearing units each including an image carrier are positioned and mounted on a main body frame, wherein the sub-unit composed of a plurality of image bearing units is positioned and supported on the main body frame. An image forming apparatus, wherein a plurality of positioning portions are integrally formed. 3. The image forming apparatus according to claim 1, wherein a positioning portion for positioning and supporting a subunit including an image bearing unit including the image bearing member is integrally formed on the main body frame. The positioning portion of the image carrier unit includes a substantially V-shaped V-shaped block for positioning and supporting at two points an end outer diameter portion of the image carrier or a bearing member which holds the outer diameter portion rotatably. An image forming apparatus comprising: 4. The image forming apparatus according to claim 3, wherein
An image forming apparatus comprising a pressing means for pressing the image carrying unit toward the V-shaped block. 5. The image forming apparatus according to claim 1, wherein a positioning portion for positioning and supporting a sub-unit composed of an image bearing unit including an image bearing member is integrally formed on the main body frame. A positioning portion of the image carrier unit, a substantially V-shaped V-shaped block for positioning and supporting the end outer diameter portion of the image carrier or a bearing member at which the outer diameter portion is rotatably held; An image forming apparatus comprising: a position restricting unit that restricts an end position of the image forming apparatus. 6. The image forming apparatus according to claim 5, further comprising a pressing unit that presses the image holding unit toward the V-shaped block and the position regulating unit. 7. The image forming apparatus according to claim 6, wherein the pressing means includes an inclined portion that is inclined along the axial direction of the image carrier on the image carrying unit side, and at least the pressing direction is V with respect to the inclined portion. An image forming apparatus, wherein a pressing body directed toward a V-shaped block is engaged to simultaneously press the image-carrying unit against the V-shaped block and the position regulating unit. 8. The image forming apparatus according to claim 3, wherein the V-shaped block constituting the positioning portion of the image bearing unit faces a driving force acting in a radial direction of the image bearing member when driving the image bearing member. An image forming apparatus having a wall serving as a single support point at a part to be formed. 9. The image forming apparatus according to claim 1, wherein a positioning unit for positioning and supporting a subunit including a transfer unit for transferring an image on the image carrier to a recording medium is integrally formed on the main body frame. In the above aspect, the positioning unit of the transfer unit is engaged with a positioning unit provided on the transfer unit side. 10. The image forming apparatus according to claim 1, wherein
In a mode in which a positioning portion for integrally positioning and supporting a sub-unit composed of an image bearing unit including an image bearing member and a transfer unit for transferring an image on the image bearing member to a recording medium is integrally formed on the main body frame. It is configured to be retractable from the positioning position of the main body frame, and secures a space for separating from the positioning position of the image carrying unit when the transfer unit is retracted to the retreat position, and when the transfer unit is set to the positioning position. An image forming apparatus comprising: a pressing unit that presses an image carrying unit toward a positioning unit. 11. The image forming apparatus according to claim 1, wherein
In a mode in which a positioning section for positioning and supporting a sub-unit composed of a latent image forming unit for writing an electrostatic latent image on an image carrier is integrally formed on a main body frame, the positioning section of the latent image forming unit includes a latent image An image forming apparatus, wherein the image forming apparatus engages with a portion to be positioned provided on a forming unit side. 12. The image forming apparatus according to claim 1, wherein the main body frame structure includes at least two sheet metal members arranged side by side at a distance from each other, and a subunit in a state where the two sheet metal members are stacked. An image forming apparatus characterized in that the respective positioning portions are simultaneously processed. 13. The image forming apparatus according to claim 1, wherein the main body frame structure includes at least two sheet metal members that are juxtaposed at a distance from each other and have a positioning unit for a subunit formed therein. An image forming apparatus to be constructed. 14. The image forming apparatus according to claim 1, wherein the main body frame structure also serves as a unit frame of a latent image forming unit for writing an electrostatic latent image on the image carrier. Forming equipment.