JPH0594056A - Image forming device - Google Patents

Abstract

PURPOSE:To form an image with high precision by positioning an image forming cartridge, an exposure means, and a bottom frame of the main body with accuracy to each other. CONSTITUTION:The device is constituted by having both of the image forming cartridge 16 and the exposure unit 17 is floatably supported 36, 45 to the main body 1, and providing positioning means 41, 51, 52, and 53 to position each of the image forming cartridge 16 and the exposure unit 17 to the specified positions against the bottom frame 2 by abutting the bottom frame 2, the image forming cartridge 16, and the exposure unit 17 to each other with movement or pressure when the upper frame 4 of the main body 1 is closed against the bottom frame 2.

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 for forming an image by an electrophotographic system such as a laser beam printer, a facsimile printer, a copying machine, and the like. A main body having an upper frame that is openably and closably connected to the main body, an image forming cartridge that has a photoconductor and an image forming apparatus around the photoconductor, and is attached and detached in the opened state of the upper frame, and a photosensitive body of the image forming cartridge. The present invention relates to an image forming apparatus provided with a sheet conveying system for providing an image transfer from a transfer sheet with a transfer sheet on a lower frame, which is provided with an exposure unit for exposing the body to an image.

[0002]

2. Description of the Related Art The main body of an apparatus is divided into an upper frame side and a lower frame side with the sheet conveying system as a boundary so that the sheet conveying system can be opened when the upper frame is opened, and sheet jam processing is performed. Making it easy.

Further, the photosensitive member and the image forming device around the photosensitive member are used as one image forming cartridge so that the image forming cartridge can be attached and detached in the opened state of the upper frame. It is possible to replace it and it is easy to maintain.

In order to form an image with high accuracy, the image forming cartridge and the exposure unit must face each other accurately. At the same time, since the image formed on the image forming unit is accurately transferred onto the transfer sheet supplied by the sheet conveying system of the lower frame, the image forming unit correctly faces the sheet conveying system of the lower frame. There must be.

Conventionally, in order to satisfy such positioning,
By mounting the image forming cartridge on the upper frame in the opened state, positioning it in advance with respect to the exposure unit fixedly mounted on the upper frame, and then closing the upper frame with the lower frame to form an image. The cartridge is positioned with respect to the lower frame via the upper frame.

[0006]

The lower frame of the main body is equipped with a sheet conveying system as well as heavy equipment such as a main motor, a drive mechanism and a fixing device, and has sufficient strength and stability. .. On the other hand, the upper frame is made lighter and smaller so that it can be easily opened and closed with respect to the lower frame. However, one end of the upper frame is only hinged to the lower frame, and the upper frame is equipped with an image forming cartridge and an exposure unit, so that the upper frame is relatively susceptible to fluctuations. It is also possible to connect the free end side of the upper frame and the lower frame with a telescopic cylinder. This allows the opening / closing operation of the upper frame to be smoothly performed under the weight of the upper frame, but the fluctuation of the upper frame cannot be sufficiently suppressed.

In addition, the upper frame is locked to the lower frame by the lock lever provided at the free end of the upper frame engaging with the pin of the lower frame. No special measures have been taken to align.

Therefore, when the image forming cartridge mounted on the upper frame in the open state as in the conventional case is positioned on the exposure unit fixedly mounted on the upper frame, the positioning between them is satisfactory. However, even if the upper frame is closed to the lower frame and the image forming cartridge is positioned with respect to the lower frame, the upper frame is difficult to be properly aligned with the lower frame,
The image forming cartridge is displaced from the lower frame by an amount corresponding to the displacement of the upper frame from the lower frame.

Therefore, even if the image exposure of the image forming cartridge is performed satisfactorily, the image formed by the image forming cartridge is transferred onto the transfer sheet conveyed by the conveying system of the lower frame. Performance deterioration, variations, and positional deviations occur, and accurate image formation cannot be expected.

Therefore, it is an object of the present invention to provide an image forming apparatus in which the image forming cartridge is accurately aligned with the exposure unit and the lower frame of the main body, and an image can be formed with high accuracy. ..

[0011]

In order to achieve the above object, the present invention provides a main body having a lower frame and an upper frame connected to the lower frame so as to be vertically opened and closed, a photoreceptor and A transfer sheet is provided in a lower frame, which has an image forming cartridge having an image forming device around it and is attached / detached in the opened state of the upper frame, and an exposure unit for performing image exposure on the photoconductor of the image forming cartridge. In an image forming apparatus provided with a sheet conveying system for transferring an image from an image forming cartridge, both an image forming cartridge and an exposure unit are supported in a floating manner on the main body, and an upper frame of the main body is closed with respect to a lower frame. The lower frame, the image forming cartridge, and the exposure unit are brought into contact with each other by the movement or the pressing at the time, and the image forming unit It is an first characterized in that each of the cartridge and the exposure unit provided with a positioning means for positioning in a predetermined position relative to the lower frame.

In this case, the positioning means can be constituted by a pair of contact portions between the image forming cartridge and the lower frame and a pair of contact portions between the exposure unit and the lower frame, and between the image forming cartridge and the lower frame. It can also be composed of a contact portion pair and a contact portion pair between the image forming cartridge and the exposure unit.

Further, according to the present invention, the image forming cartridge can be attached to and detached from the lower frame, and when the image forming cartridge is attached to the image forming cartridge attaching portion of the lower frame, the image forming cartridges are brought into contact with each other so that the image forming cartridge is attached to the lower frame. The exposure unit supports the exposure unit in a floating manner, and the exposure unit abuts and exposes the exposure unit and the lower frame by movement or pressing when the upper frame is closed with respect to the lower frame. A second feature is that a positioning means for positioning the unit at a predetermined position with respect to the lower frame is provided.

Instead of the positioning means in this case, the exposure unit and the image forming cartridge are brought into contact with each other by the movement or pressing when the upper frame is closed with respect to the lower frame, and the exposure unit is moved to a predetermined position with respect to the lower frame. It is also possible to provide a positioning means for positioning in.

[0015]

In the above-mentioned constitution of the first feature of the present invention, when the upper frame of the main body is closed with respect to the lower frame,
The image forming cartridge and the exposure unit, which are floatably supported by the main body, are moved to the lower frame side by movement or pressing due to the closing operation of the upper frame,
Since the positioning means abut against each other between the lower frame, the image forming cartridge and the exposure unit and position them in a predetermined positional relationship, the image forming cartridge is positioned regardless of the positional accuracy of the upper frame. Both of them are properly positioned, and image formation by image exposure from the exposure unit and transfer of the image to the sheet conveyed by the sheet conveying system of the lower frame can be accurately achieved.

If the positioning means is composed of the contact portion pair between the image forming cartridge and the lower frame and the contact portion pair between the exposure unit and the lower frame, both the image forming cartridge and the exposure unit are positioned on the lower frame side. However, the positioning between the image forming cartridge and the exposure unit can be uniquely determined on the lower frame. Further, when the positioning means is composed of the contact portion pair between the image forming cartridge and the lower frame and the contact portion pair between the image forming cartridge and the exposure unit, the image forming cartridge is directly positioned with respect to each of the exposure unit and the lower frame. You can meet each other.

According to the above configuration of the second feature of the present invention,
The image forming cartridge can be mounted directly on the lower frame, and at the same time, can be directly positioned between the lower frame and the supporting frame for the upper frame. When the upper frame is closed with respect to the lower frame, the exposure unit, which is supported in a floating manner, is moved or pressed accordingly, and the positioning means between the exposure unit and the lower frame are brought into contact with each other. The exposure unit can be directly positioned with respect to the lower frame to uniquely achieve positioning with the image forming cartridge.

Further, when the exposure unit moved or pressed by closing the upper frame to the lower frame and the image forming cartridge mounted and positioned on the lower frame are brought into contact with each other, the exposure is performed. The unit can be positioned directly with respect to the imaging cartridge.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus as a first embodiment of the present invention shown in FIGS. 1 to 4 will be described.

This embodiment shows the case of a laser beam printer, and as shown in the overall schematic structure of FIG. 1, the apparatus main body 1 can be opened and closed by a lower frame 2 and a hinge shaft 3 on the lower frame 2. The upper frame 4 is connected and supported.

The upper frame 4 is biased by a biasing means (not shown) so as to maintain the open state shown in FIG. 1, and is provided at its free end when the upper frame 4 is closed as shown in FIG. The lock lever 5 is elastically engaged with the lock pin 6 fixed to the lower frame 2 so as to be locked in the closed state.

This lock is released by rotating the lock lever 5 against the urging force in the engaging direction acting on the lock lever 5 by the operating lever 7 to release the lock pin 5 from the lock pin 6.

The upper frame 4 has a photosensitive drum 11 and
An image forming cartridge 1 equipped with an image forming device such as a charger 12, a developing device 13, a cleaning device 14 and an eraser 15 arranged around the photosensitive drum 11.
6 is provided, and a laser scanning unit 17 for exposing the photosensitive drum 11 to an image is provided as an exposing unit on the image forming cartridge 16.

The laser scanning unit 17 generates a laser beam 18 modulated according to an image signal toward the photosensitive drum 11 as shown in FIG. 2 to perform image exposure.

After the residual toner is removed by the cleaning device 14 and the residual charge is removed by the eraser 15, the surface of the photosensitive drum 11 is uniformly charged by the charging charger 12, and the surface after the charging is subjected to the image exposure. In response, an electrostatic latent image according to the image signal is formed.

The electrostatic latent image on the photosensitive drum 11 is developed by the developing device 13.
The toner is developed and visualized.

On the other hand, the lower frame 2 is provided with the photosensitive drum 1
Transfer sheet 1 used for transferring the visible image formed on
A sheet conveying system 21 for conveying the sheet 9 and performing necessary processing is provided.

The sheet conveying system 21 includes a photosensitive drum 1 when the upper frame 4 and the lower frame 2 are closed.
It has a transfer charger 22 which is opposed to the surface after the development of No. 1 and before cleaning at a predetermined interval and position as shown in FIG.

The transfer charger 22 forms a transfer portion 23 between itself and the photosensitive drum 11, and electrostatically transfers the visible image formed on the photosensitive drum 11 onto the transfer sheet 19 passing through the transfer portion 23. ..

The sheet conveying system 21 includes the lower frame 2
A sheet feeding roller 25 that feeds out the transfer sheets 19 in the sheet feeding cassette 24 mounted at one end of the sheet feeding roller 25, and the transfer sheets 19 delivered by the sheet feeding roller 25 are once received in a stopped state and then exposed to light. After the timing roller 26 that is re-driven at the timing when the leading edge of the image on the drum 11 coincides and sends the transfer sheet 19 toward the transfer section 23, and the transfer sheet 19 after transfer via the transfer section 23 is received and fixed. And a fixing device 27 for discharging.

As a result, the sheet conveying system 21 provides the transfer sheet 19 for image transfer from the photosensitive drum 11 with the upper frame 4 closed with respect to the lower frame 2, and fixes the transfer sheet 19 after transfer. Processing can be performed to effect image formation on the sheet.

Both the image forming cartridge 16 and the laser scanning unit 17 are floatably supported by the upper frame 4, and the image forming cartridge 16 is detachable from the upper frame 4.

This will be specifically described. As shown in FIGS. 1 and 3, the image forming cartridge 16 has flange portions 31 on both side surfaces thereof, and a guide rail 33 is fixedly provided on an inner frame 32 in the upper frame 4 so as to face the flange portions 31. The rear end of the guide rail 33 and the rear end of the support space 34 of the image forming cartridge 16 are opened outside the main body 1 by opening the upper frame 4 as shown in FIG.

While the image forming cartridge 16 is being inserted into the support space 34 in this open state, the flange portions 31 on both side surfaces are fitted to the guide rails 33, so that the image forming cartridge 16 is placed in the support space 34. The image forming cartridge 16 can be mounted and supported so that the image forming cartridge 16 can be pulled out from the upper frame 4 in the opened state by the reverse operation.

The guide rail 33 has a large play in the vertical direction with respect to the flange portion 31, and also has a small play in the horizontal direction.
It is supported so that it can float. However, the upper and lower slide shafts 35 are supported on the upper wall of the guide rail 33 and the spring 3
6 has a pressing guide 37 which is urged downward by 6, and a flange portion 31 which is received by the guide rail 33 is pressed against the lower wall of the guide rail 33 to form the image forming cartridge 16
To stabilize.

Further, the laser scanning unit 17 is
Positioning pins 41 are provided on the front and rear sides of both sides, and a part of a resin-made square bush 42 fitted to the positioning pins 41 is fitted to a sliding window 43 of the inner frame 32 so as to be vertically movable. 17 is supported so as to have a large play vertically and a little play left and right, and is floatable with respect to the upper frame 4.

However, the square bush 42 is pressed against the lower end portion of the sliding window 43 by a spring 45 that is exerted between the square bush 42 and a spring receiver 44 fixed to the upper portion of the inner frame 32, and laser scanning. Unit 17
To stabilize.

Therefore, both the image forming cartridge 16 and the laser scanning unit 17 are supported by the upper frame 4 so as to be floatable, and are stabilized in the lower moving position by the springs 36 and 45. It is moved downward with the movement when closed.

When the image forming cartridge 16 and the laser scanning unit 17 are moved downward in accordance with the closing operation of the upper frame 4, they are brought into contact with the side of the lower frame 2 and positioned with respect to the lower frame 2. The pair of contact portions are positioning pins 51 projecting from the front and rear sides of the image forming cartridge 16, positioning recesses 52 on the lower frame 2 side for receiving the positioning pins 51, and the laser scanning unit 17.
It is provided as a combination of the positioning pin 41 projecting on both sides of and the positioning recess 53 on the side of the lower frame 2 that receives the positioning pin 41.

The positioning recesses 52 and 53 are formed in resin blocks 54 and 55, respectively.
The positioning recesses 52, 53 are fixedly provided at predetermined positions by fitting the inner surfaces of the side walls of the lower frame 2 with 4, 55. However, the positions of the blocks 54 and 55 may be finely adjusted by a known method.

The positioning recess 52 of the lower frame 2 receives the positioning pin 51 of the image forming cartridge 16 which is moved downward in accordance with the closing operation of the upper frame 4 as shown in FIGS. The image forming cartridge 16 is positioned at a predetermined position with respect to the lower frame 2 without being influenced by the upper frame 4 having a play therebetween.

Further, the positioning recess 53 of the lower frame 2
2 receives the positioning pin 41 of the laser scan unit 17 which is moved downward in accordance with the closing operation of the upper frame 4 as shown in FIGS. -Position the scanning unit 17 in place with respect to the lower frame 2 without the influence of the upper frame 4 having play between them.

Therefore, the image forming cartridge 16 and the lower frame 2 are directly positioned with high precision, and the image forming cartridge 16 and the laser scanning unit 17 are
Although the lower frame 2 is interposed, the positioning recesses 52 and 53 in the lower frame 2 directly and accurately position the image forming cartridge 16 and the laser scan unit 17 to uniquely and accurately perform positioning.

Therefore, the image forming cartridge 16 receives a highly accurate image exposure from the laser scanning unit 17 to form an image, and the transfer sheet 1 to which the formed image is supplied.
9 can be transferred with high accuracy, and an image can be formed with high accuracy.

In this embodiment, the image forming cartridge 16
While the laser scanning unit 17 is supported by the upper frame 4 so as to be floatable, the same operation and effect can be achieved by supporting one or both of them by the lower frame 2 in a floating manner.

In some cases, the image forming cartridge 1
The floating support of the laser scanning unit 6 and the laser scanning unit 17 may be floated only in the necessary limited direction, and the positioning with respect to the lower frame 2 side may be performed in the floating direction.

The second embodiment of the present invention shown in FIG. 5 is the first embodiment.
The image forming cartridge 16 in the above embodiment is removably directly attached to the support space 61 provided in the lower frame 2, and the positioning pin 51 is used for the positioning recess 52 at the time of this attachment.
The lower frame 2 at the same time as mounting by fitting
Can be positioned at a predetermined position.

As a result, the simplification and weight saving of the structure on the side of the upper frame 4 can be achieved.

There is no change in other constitutions and operational effects,
The description is omitted.

In the third embodiment of the present invention shown in FIGS. 6 and 7, the play between the flange portion 31 of the image forming cartridge 16 and the guide rail 33 in the first embodiment is eliminated, and the guide rail is provided. 33 is made of resin, and the integrally formed projection 71 is fitted into the sliding window 72 of the inner frame 32 so as to be vertically movable, so that the image forming cartridge 16 has a large up and down play and a little left and right play. It is supported and floatable. However, a spring 74 that acts between the guide rail 33 and a spring receiver 73 that is fixed to the inner frame 32 is used to press and hold the image forming cartridge 16 in the downward position to stabilize it.

The laser scanning unit 17 has positioning protrusions 81 projecting downward at four corners of the bottom surface of the image forming cartridge 16 facing the image forming cartridge 16, and the positioning protrusions 81 are formed on the upper surface of the image forming cartridge 16. A positioning recess 82 for receiving and positioning the laser scanning unit 17 with respect to the image forming cartridge 16 is provided.

The positioning protrusion 81 is formed integrally with the resin case of the laser scan unit 17, and the positioning recess 82 is formed in a resin block 83, which is fitted on the upper wall of the image forming cartridge 16. There is.

The other structure is the same as that of the first embodiment. When the upper frame 4 and the lower frame 2 are closed,
With this movement, the image forming cartridge 16 and the laser
The scanning unit 17 is moved downward, and this movement causes the image forming cartridge 16 to be directly positioned with respect to the lower frame 2 as in the case of the first embodiment. On the other hand, the laser scan unit 17 is brought close to the image forming cartridge 16 positioned on the lower frame 2 so that the positioning protrusion 81 and the positioning recess 82 are brought into contact with each other, and the laser scan unit 17 becomes the image forming cartridge. Positioned directly between 16 and.

Therefore, in the case of the present embodiment, the image forming cartridge 16 is directly positioned between both the lower frame 2 and the laser scanning unit 17, and it is possible to satisfy high positioning accuracy with a simple structure.

The fourth embodiment of the present invention shown in FIG. 8 is the third embodiment.
The image forming cartridge 16 in this embodiment is different from that in the third embodiment in that the image forming cartridge 16 is mounted and positioned on the lower frame 2 in the same manner as in the second embodiment.

Therefore, the upper frame 4 is simplified and downsized as compared with the case of the third embodiment.

[0057]

According to the first aspect of the present invention, when the upper frame of the main body is closed to the lower frame, the image forming cartridge and the exposure unit which are floatably supported by the main body are closed by the upper frame. When the lower frame, the image forming cartridge, and the exposure unit are brought into contact with each other, the positioning means abut against each other by being moved or pressed together, and they are positioned in a predetermined positional relationship. Since it can be achieved with high accuracy without any influence of the image forming cartridge, the image forming cartridge receives the image exposure with high accuracy from the exposure unit to form an image, and the formed image is transferred to the transfer sheet sent by the sheet conveying system. It is possible to transfer the image with high accuracy and form the image with high accuracy.

If the positioning means is composed of a pair of contact portions between the image forming cartridge and the lower frame and a pair of contact portions between the exposure unit and the lower frame, both the image forming cartridge and the exposure unit are positioned on the lower frame side. However, the positioning between the image forming cartridge and the exposure unit on the lower frame can be uniquely determined on the lower frame side, and the required accuracy can be easily obtained. Further, when the positioning means is composed of the contact portion pair between the image forming cartridge and the lower frame and the contact portion pair between the image forming cartridge and the exposure unit, the image forming cartridge is directly positioned with respect to each of the exposure unit and the lower frame. They can be matched with each other, the positioning structure can be simplified, and the positioning accuracy can be easily obtained.

According to the second aspect of the present invention, since the image forming cartridge can be directly mounted on the lower frame and directly positioned with respect to the lower frame, the structure for supporting and positioning the image forming cartridge can be improved. To simplify.
Further, the supporting load on the upper frame can be reduced, and the structure and weight of the upper frame itself can be simplified.

When the upper frame is closed with respect to the lower frame, the exposure unit, which is supported in a floating manner, is moved or pressed accordingly, so that the positioning means between the exposure unit and the lower frame abut each other. Since the exposure unit is directly positioned with respect to the lower frame, the positioning with the image forming cartridge is uniquely achieved on the lower frame side, and the required accuracy can be easily obtained.

Further, when the positioning unit between the exposure unit which is moved or pressed by the closing of the upper frame to the lower frame and the image forming cartridge mounted and positioned on the lower frame are brought into contact with each other, the exposure is performed. The unit can be positioned directly with respect to the image forming cartridge, which simplifies the positioning structure and facilitates positioning accuracy.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an image forming apparatus as a first embodiment of the present invention.

2 is a cross-sectional view showing a state in which the upper frame of the apparatus of FIG. 1 is closed, in a direction parallel to a part of the sheet passing direction.

3 is a cross-sectional view showing the same state as FIG. 2 in a direction perpendicular to the sheet passing direction.

FIG. 4 is a partial side view showing a floating support state of a laser scanning unit of the apparatus of FIG.

FIG. 5 is a schematic configuration diagram of an image forming apparatus showing a second embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of an image forming apparatus showing a third embodiment of the present invention.

7 is a cross-sectional view of a part of the apparatus of FIG. 6 showing a positioning state between an image forming cartridge and a laser scanning unit in a direction perpendicular to a sheet passing direction.

FIG. 8 is a schematic configuration diagram showing an image forming apparatus according to a fourth embodiment of the present invention.

[Explanation of symbols]

 1 Main Body 2 Lower Frame 3 Hinge Axis 4 Upper Frame 11 Photosensitive Drum 16 Image Cartridge 17 Laser Scan Unit 19 Transfer Sheet 21 Sheet Conveying System 31 Flange 32 Inner Frame 33 Guide Rail 34, 61 Support Space 35 Vertical Slide Axis 36 , 45, 74 Spring 41, 51 Positioning pin 42 Square bush 43, 72 Sliding window 52, 53, 82 Positioning recess 71 Protrusion 81 Positioning protrusion

Claims (5)

[Claims] 1. A main body having a lower frame and an upper frame connected to the lower frame so as to be vertically opened and closed, a photoconductor and an image forming device around the same, and attached and detached in an opened state of the upper frame. Image forming apparatus having an image forming cartridge and an exposure unit for exposing a photosensitive member of the image forming cartridge to an image, and a sheet conveying system for transferring a transfer sheet from the image forming cartridge to a lower frame. In the above, both the image forming cartridge and the exposure unit are supported in a floating manner on the main body, and the movement or pressing when the upper frame of the main body is closed with respect to the lower frame causes the space between the lower frame, the image forming cartridge and the exposure unit. Abutting each other with the image forming cartridge and the exposure unit to the lower frame. An image forming apparatus characterized in that a positioning means for positioning at a predetermined position that. 2. The image forming apparatus according to claim 1, wherein the positioning means is a pair of contact portions between the image forming cartridge and the lower frame and a pair of contact portions between the exposure unit and the lower frame. 3. The image forming apparatus according to claim 1, wherein the positioning means includes a contact portion pair between the image forming cartridge and the lower frame and a contact portion pair between the image forming cartridge and the exposure unit. 4. A main body having a lower frame and an upper frame connected to the lower frame so as to be able to open and close vertically, a photoconductor and an image forming device around the same, and attached and detached in an opened state of the upper frame. Image forming apparatus having an image forming cartridge and an exposure unit for exposing a photosensitive member of the image forming cartridge to an image, and a sheet conveying system for transferring a transfer sheet from the image forming cartridge to a lower frame. In (1), the image forming cartridge is attachable to and detachable from the lower frame, and when the image forming cartridge is attached to the image forming cartridge mounting portion of the lower frame, the image forming cartridges come into contact with each other to position the image forming cartridge at a predetermined position with respect to the lower frame. The exposure unit supports the exposure unit so that the exposure unit can float and the upper frame can support the lower unit. An image forming apparatus provided with a positioning means for abutting between the exposure unit and the lower frame to position the exposure unit at a predetermined position with respect to the lower frame by moving or pressing when the shutter is closed. .. 5. A main body having a lower frame and an upper frame connected to the lower frame so as to be vertically opened and closed, a photoconductor and an image forming device around the same, and attached and detached in an opened state of the upper frame. Image forming apparatus having an image forming cartridge and an exposure unit for exposing a photosensitive member of the image forming cartridge to an image, and a sheet conveying system for transferring a transfer sheet from the image forming cartridge to a lower frame. In (1), the image forming cartridge is attachable to and detachable from the lower frame, and when the image forming cartridge is attached to the image forming cartridge mounting portion of the lower frame, the image forming cartridges come into contact with each other to position the image forming cartridge at a predetermined position with respect to the lower frame. The exposure unit supports the exposure unit so that the exposure unit can float and the upper frame can support the lower unit. An image forming device is provided with a positioning means for abutting between the exposure unit and the image forming cartridge to position the exposure unit at a predetermined position with respect to the lower frame by moving or pressing when the shutter unit is closed. apparatus.