JPH1020613A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color image forming device capable of realizing the positioning of plural developing devices with respect to a photoreceptor belt and stabilizing developing performance in the respective developing devices while satisfying the miniaturization of the entire device. SOLUTION: This color image forming device is equipped with a rotary type color developing unit 6 opposed to the photoreceptor belt 1 laid over turning roller 2 and 3 and a black developing device 7, and it is provided with an engaging hole 101C functioning as a positioning part for positioning the developing device 7 with respect to the belt 1 on the upper surface of the case member 101 of the unit 6 positioned with respect to the belt 1 by using a device main body side plate 102. When the device 7 is moved toward the belt 1 on the case member 101, a projection part 41A formed on the lower surface of a developer container 41 is engaged and locked in the engaging hole 101C, thereby the device 7 is positioned.

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, a facsimile, and a printer.
The present invention relates to an image forming apparatus having a plurality of developing devices facing an image carrier.

[0002]

2. Description of the Related Art Conventionally, as this type of image forming apparatus,
One having a plurality of developing devices each having a single developing device, or having a plurality of developing devices supported by a rotating support,
It is known that the image forming apparatus includes a plurality of developing devices including a rotary developing device that switches a developing device positioned at a developing position facing a latent image carrier belt by rotation of the rotating support.
Even in such an image forming apparatus having a plurality of developing devices, technical development for reducing the size of the entire device is being advanced. From the viewpoint of achieving such miniaturization, the present applicant has proposed in Japanese Patent Application No. 8-104623 an image forming apparatus in which a belt-shaped image carrier is provided over at least two roller members. According to the image forming apparatus according to this proposal, since the image carrier can be erected such that the extending portion between the roller members of the image carrier is vertical or slightly oblique from that direction, the image carrier having a drum shape The thickness in the horizontal direction can be reduced as compared with the case where a body is used, and the size of the apparatus main body can be reduced. In addition, the extended portion of the image carrier can be made long, and a plurality of developing devices can be arranged side by side in the vertical direction so as to face the extended portion, so that the size of the apparatus main body can be further reduced.

Further, the present applicant has filed Japanese Patent Application No. Hei 8-23210.
Wherein the image carrier comprises a belt-shaped image carrier, and a plurality of developing devices opposed to the image carrier at different positions, wherein at least two adjacent developing devices of the plurality of developing devices face each other. There has been proposed an image forming apparatus in which the image carrier is pushed outward using a backup member between opposing portions. According to the image forming apparatus according to this proposal, the belt supporting members located at both ends of the extended portion of the image carrier while securing the interval between the adjacent developing devices with the portion pushed outward by the backup member therebetween. Since it is possible to set the interval between the roller members as relatively small, when disposing the plurality of developing devices, the developer carrier is wound around the roller member as a portion on the image carrier that is in contact with or close to the developer carrier. While satisfying the desire to use a part that is somewhat distant from where
The size of the image forming apparatus main body can be reduced.

[0004]

In order to stabilize the developing performance even in an image forming apparatus including a plurality of developing devices and miniaturizing the entire device, such as the image forming device according to the above proposal, In order to maintain a constant gap or nip width between the developer carrier and the image carrier of each developing device, it is necessary to position each developing device with respect to the image carrier. From the viewpoint of reducing the size of the entire image forming apparatus, it is desired that the positioning mechanism for positioning the developing device take up as little space as possible.

The present invention has been made in view of the above background, and an object of the present invention is to perform positioning of a plurality of developing devices with respect to an image carrier while satisfying a demand for miniaturization of the entire image forming apparatus. Another object of the present invention is to provide an image forming apparatus capable of stabilizing the developing performance of each developing device.

[0006]

According to a first aspect of the present invention, there is provided an image forming apparatus including a plurality of developing devices opposed to an image carrier. The case member of the reference developing device positioned with respect to the image carrier is provided with a positioning portion for positioning another developing device adjacent to the reference developing device with respect to the image carrier. It is.

According to a second aspect of the present invention, the developing device includes:
2. The image forming apparatus according to claim 1, further comprising a movable developing device configured to be movable between a developing position facing the image carrier and a position separated from the developing position. A guide member for guiding the movement of the movable developing device is provided on a case member of the matching developing device.

According to a third aspect of the present invention, the plurality of developing devices are arranged side by side in the vertical direction, and a developing opening for exposing the developer carrier of the lowermost developing device is provided on a side of the lowermost developing device. 2. The image according to claim 1, further comprising: a light irradiating device provided in the unit, and irradiating light passing near the developing opening to the surface of the image carrier to form a latent image below the lowermost developing device. In the forming apparatus, a space extending from the lower end of the developing opening extends vertically downward so as to shield a space adjacent to the developing opening and a space adjacent to an exposed surface of the light emitting optical member of the light irradiation device. A light through hole through which light emitted from the light emitting optical member of the light irradiation device penetrates is formed in the shielding member, and a horizontal direction from a lower end of the developing opening toward the image carrier is provided. It is characterized by having provided an eaves extending to the sea.

According to a fourth aspect of the present invention, as the developing device,
2. The image forming apparatus according to claim 1, further comprising a rotary developing device in which a plurality of developing devices are supported by a rotary support. A stand unit for allowing the rotary developing device to stand on a case member of the rotary developing device. Is provided.

In the image forming apparatus according to any one of the first to fourth aspects, a reference developing device, which is a reference for positioning each developing device among a plurality of developing devices, is positioned with respect to the image carrier.
And another developing device adjacent to the reference developing device,
Instead of positioning using the member on the image forming apparatus main body side, positioning is performed using a positioning portion provided on the case member of the reference developing device. By this positioning, the other developing device is indirectly positioned with respect to the image carrier so that the gap or nip width between the developer carrier and the image carrier becomes constant.

Particularly, in the image forming apparatus according to the second aspect,
Instead of guiding the movable developing device with a guide portion provided on a member on the image forming apparatus main body side, by guiding the movable developing device with a guide portion provided on a case member of a developing device adjacent to the movable developing device, the image carrier is It is moved between an opposing developing position and a position separated from the developing position.

In the image forming apparatus according to the third aspect of the present invention, the developer is loaded from a developing opening provided at a side of the lowermost developing device among a plurality of developing devices arranged in the vertical direction. The body is exposed, and from this development opening,
The developer used in the lowermost developing device may scatter into the image forming apparatus main body. On the other hand, light for forming a latent image on the surface of the image carrier is emitted from an emission optical member of a light irradiation device provided below the lowermost developing device, and a space adjacent to the developing opening is provided. The light passes through a light through hole formed in a shielding member that shields a space adjacent to an exposed surface of the light emitting optical member, and reaches a surface of the image carrier located near a lower end of the developing opening. Here, by forming the light through hole in a shielding member extending vertically downward from the lower end of the developing opening, the developer scattered from the developing opening and falls vertically downward due to gravity, airflow, or the like. The falling direction is substantially parallel to the surface of the side plate on which the light through hole is formed, so that the developer falling by its own weight or the like passes through the light through hole and the light emitting optical member. To make it difficult to enter the space adjacent to the exposed surface. Further, an eave provided so as to extend from the lower end of the developing opening toward the image carrier receives the developer scattered from the developing opening and prevents the developer from falling toward the light through hole.

In the image forming apparatus according to the present invention, when the rotary developing device in which the plurality of developing devices are supported by the rotary support is detached from the image forming device and placed outside the device,
The developing device is allowed to stand alone by a stand provided on a case member of the rotary developing device.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a color image forming apparatus will be described below. First, the configuration and operation of the entire color image forming apparatus according to the present embodiment will be described. FIG. 2 is an overall schematic configuration diagram. FIG.
In, a belt-shaped photoconductor as an image carrier (hereinafter, referred to as
A photoreceptor belt 1 is provided between the rotating rollers 2 and 3, and is rotated and conveyed clockwise in the drawing by the driving of the rotating rollers 2 and 3. Around the photoreceptor belt 1, a charging charger 4 as a charging device, a laser writing unit 5 as a light irradiation device, and three developing devices containing yellow, magenta, and cyan color developers, respectively, were provided. A rotary color developing unit as a rotary developing device (hereinafter referred to as a color developing unit) 6,
A black developing device 7 or the like as a developing device containing a black developer different from the color developing unit 6 is provided.

The laser writing unit 5 contains a semiconductor laser (not shown), a polygon mirror 5B rotated by a drive motor 5A, an f-θ lens 5C, and a mirror 5D in a unit case 5E as a holding housing.
It is built into the lower part of the device body. A slit-shaped exposure opening to which an optical window material 5F as an optical member for light emission is attached is provided in a portion of the upper surface of the unit case 5E through which the light beam passes. Paper cassette 1
A bottom plate (not shown) is provided above the laser writing unit 5 above the upper part 7. The laser writing unit 5 is incorporated on the bottom plate, and left and right in the axial direction of the roller (rear side and front side in FIG. 2) to support each unit.
A side plate (not shown) of the apparatus main body provided in the apparatus is assembled to the bottom plate.

Further, the charging position by the charging charger 4, the irradiation position of the light beam from the laser writing unit 5, and the cleaning position by the photosensitive member cleaning blade 15A are the lower rotation of the two rotation rollers. It is set at a portion where the photosensitive belt 1 is wound around the roller 2.

Each of the color developing unit 6 and the black developing device 7 has a developing roller as a developer carrying member which comes close to or in contact with the photoreceptor belt 1 at a predetermined position. It has the function of visualizing by contact development or contact development.

The upper rotating roller 3 of the photosensitive belt 1
An intermediate transfer belt 10 as an intermediate transfer member is provided so as to come into contact with a portion wound around the intermediate transfer belt. The intermediate transfer belt 10 is installed to be inclined between the rotation rollers 11 and 12, and is rotated and conveyed counterclockwise in the drawing by driving the rotation rollers 11 and 12. The extended portion on the lower left side of the inclined intermediate transfer belt 10 in the drawing is in contact with the portion wound around the upper rotating roller 3 of the photosensitive belt 1, and the first time on the photosensitive belt 1 Is transferred onto the intermediate transfer belt 10 by a bias brush 13 as a primary transfer member provided inside the intermediate transfer belt 10 (primary transfer). Then, by repeating the same process, the second visualization, the third visualization, and the fourth visualization are superimposed on the intermediate transfer belt 10 so that no positional deviation occurs. Transcribed. The winding portion of the intermediate transfer belt 10 around the rotation roller 11 includes:
A transfer roller 14 as a secondary transfer member is provided so as to be in contact with or separated from the intermediate transfer belt 10, and the transfer roller 14 transfers an image superimposed on the intermediate transfer belt 10 onto a transfer sheet as a transfer material. (Secondary transfer). Here, the distance on the intermediate transfer belt 10 from the primary transfer position to the secondary transfer position is set to be equal to or longer than the maximum image output length.

The cleaning unit 15 for cleaning the surface of the photosensitive belt 1 includes a cleaning blade 1
5A, a waste toner collecting container 15B and the like. The cleaning unit 16 for cleaning the surface of the intermediate transfer belt 10 includes a cleaning blade 16.
A, an auger 16B for conveying toner is provided. During image formation, the cleaning blade 16A of the intermediate transfer belt cleaning unit 16
And is pressed against the surface of the intermediate transfer belt 10 as shown in the drawing only during cleaning after the secondary transfer.

FIG. 3 is a schematic configuration diagram of the inside of the color developing unit 6 and the black developing device 7, and FIG. 4 is a perspective view of the color developing unit 6. In the color developing unit 6, an inner casing 21 which is a rotating body has a rotation center O.
The inner casing 21 is provided rotatably around
Can be rotated clockwise in the figure by driving a drive mechanism (not shown). The inner casing 21 has yellow, magenta, and cyan developing units 22 (-Y,
M, C) are held together. Each color developer 22 (−
Y, M, and C) have the same form and are configured to perform the same operation.

Also, one of the two extending portions between the rotating rollers 2 and 3 of the photosensitive belt 1 on the color developing unit 6 side (black developing device 7 side) is pushed outward. A backup roller 35 is provided so that the upper portion of the one extending portion is transported in the vertical direction, and the lower portion is transported in a state of being slightly inclined. The black developing device 7 is opposed to the upper part of the extended portion of the photosensitive belt 1 extruded by the backup roller 35, and the color developing unit 6 is opposed to the lower part of the extended portion. Here, the extending portion of the intermediate transfer belt 10 is inclined more greatly than the photosensitive belt 1 so that the extending portion of the photosensitive belt 1 is substantially vertical.
A space for arranging the waste toner collecting container 15B of a fixed capacity of the cleaning unit 15 can be secured.

At the developing position in the color developing unit 6, the photosensitive belt 1 is rotated so that the developing roller 23 rotates in the same direction as the photosensitive belt 1 at a predetermined linear velocity ratio. They are arranged facing each other. Below the developing roller 23 at the developing position, a supply roller 25 made of an elastic material such as foamed polyurethane rubs with the developing roller 23 at a rubbing portion, and the developing roller 2
3 so as to rotate in the same direction with a predetermined linear velocity ratio. Supply roller 2 in a rubbing portion with developing roller 23
A developing blade 26 made of a thin plate having a spring property such as stainless steel is provided on the downstream side in the rotation direction of 5 such that one end thereof is in contact with the developing roller 23. Further, a screw-shaped first toner conveying member 27 described later conveys toner as a developer from the near side to the far side in FIG.

As shown in FIG. 4, a toner container 29 is provided at one end side (front side in FIG. 4) of the color developing unit 6 in the axial direction of the developing roller. The screw-shaped first toner conveying member 27 is disposed in parallel with the developing roller 23 and the supply roller 25 from the toner container 29 to the developing device side plate on the rear side of the color developing device unit 6 in the drawing. The toner is conveyed from the front of the drawing toward the back. Then, it is interlocked with the developing roller 23 and the supply roller 25, and rotates at a predetermined linear velocity ratio therewith. The partition plate 24 of each developing unit is disposed so that a part thereof is in contact with the supply roller 25, and a toner transport space surrounding the first toner transport member 27 is formed by the developing roller 23 and the supply roller 25. Is done. The toner supplied on the supply roller 25 is supplied to the surface of the developing roller 23 by the supply roller 25, charged, and carried on the surface of the developing roller 23. The toner carried on the surface of the developing roller 23 is thinned by the developing blade 26, and develops the electrostatic latent image formed on the surface of the photosensitive belt 1.

The toner that has not been used in the developing step is transferred to the toner storage section 29 by the first toner conveying member 27.
Is transported to the rear side of the developing device on the side opposite to the front side, and reaches the toner circulating section provided outside the effective diameter portion of the developing roller 23 and the supply roller 25 in the axial direction. It falls to the lower part of the developing device 22. At the lowermost part of the developing device 22 at the developing position, a screw-shaped second toner conveying member 28 is provided with a developing roller 23 and a supply roller 25.
And disposed in parallel with the first toner conveying member 27,
The toner is rotated so as to convey the toner in a direction opposite to that of the first toner conveying member 27, and conveys the toner not used in the developing process to the toner storage unit 29. By appropriately setting the toner transport amount of the first toner transport unit 27 and the second toner transport member 28, the supply loaf 25 can be detected without detecting the toner amount in the developing unit 22 or performing complicated toner supply amount control. A small color developing unit 6 can supply toner to the top, has a large degree of freedom in layout, and has a small sectional occupation ratio with respect to the photoreceptor belt 1. The toner cartridge 30 shown in FIG. 4 is detachable from the toner container 29 and can be replaced when toner is supplied.

The black developing device 7 is a developing device of a type in which black toner is contained in a developing container 41. When the toner is exhausted, the life of the developing device is replaced. It is a vessel. Like the developing units 22 of the color developing unit 7, the developing roller 23 faces the photosensitive belt 1 so that the developing roller 23 rotates in the same direction as the moving direction of the photosensitive belt 1 with a predetermined linear velocity ratio. It is arranged. Further, behind the developing roller 23 opposite to the developing position facing the photosensitive belt 1,
A supply roller 25 made of an elastic material such as foamed polyurethane is provided so as to rub against the developing roller 23 in the rubbing portion, and to rotate in the same direction as the developing roller 23 at a predetermined linear velocity ratio. A developing blade 26 made of a thin plate having a property is provided so that one end thereof is in contact with the developing loaf 23. In the developing container 41, a first agitator 42 and a second agitator 43 for transporting and stirring the toner toward the supply roller 25 and the developing roller 23 are provided. Here, a developing cartridge of a type containing toner is used, but a developing device of a type that replaces the toner cartridge and replenishes the toner like the color developing unit 6 may be used. The black developing device 7 is movable in the horizontal direction with respect to the photosensitive belt 1, is separated from the photosensitive belt 1 during non-developing, and reaches a developing position where the developing roller 23 approaches or contacts the photosensitive belt 1 during developing. Perform a separating operation such as moving.

The color image forming apparatus according to the present embodiment includes a photosensitive belt 1, a charging charger 4, an intermediate transfer belt 10, a cleaning unit 16,
The registration roller 20 </ b> B is integrally formed as a process cartridge 31. The waste toner collecting container 15
B is exchangeably incorporated into the process cartridge 31. In addition, the process cartridge 31
The surface of the registration roller 20B in the case exterior part also has a function as a conveyance guide.

Here, the waste toner scraped off from the surface of the intermediate transfer belt 10 by the cleaning blade 16A is supplied to the auger 1 provided in the cleaning unit 16.
6B, the paper is conveyed to the front side in the figure, and further conveyed to the waste toner collecting container 15B by a conveying member (not shown) provided on the front side of the process skirt ridge 31 to be collected. Thereby, the process cartridge 31
Since the waste toner can be recovered without replacing the cartridge, the life of the process cartridge 31 can be extended.

The transport roller 19 and the registration roller 2
0, transfer roller 14, fixing roller 49 of fixing device 49
The transport paths to A and B are arranged almost in parallel with the inclined extending portion of the intermediate transfer belt 10 to reduce the size of the apparatus main body.

The image forming process by the above-described color image forming apparatus is performed as follows. First, the formation of a multicolor image is performed according to the image forming system described below. When the laser writing unit 5 is driven based on a color image signal sent from an external image reading device or a host computer, a semiconductor laser (not shown)
The light beam (laser beam) generated in is scanned by a borgon mirror 5B rotated by a drive motor 5A,
The optical path is bent by the mirror 5D through the f-θ lens 5C, emitted from the optical window member 5F to the outside of the unit case 5E, and exposed on the outer peripheral surface of the photoreceptor belt 1 uniformly charged in advance by the charging charger 4. , An electrostatic latent image is formed.

Here, the image pattern to be exposed is a single-color image pattern when a desired full-color image is separated into yellow, magenta, cyan, and black. The electrostatic latent images of the three colors formed on the photoreceptor belt 1 are sequentially moved to developing positions of the yellow, magenta, and cyan developing units by the rotation operation of the color developing unit 6 to face the photoreceptor belt 1. And a single color image of each color is formed.
At this time, the black developing device 7 is retracted from the developing position facing the photosensitive belt 1 to the non-developing position. The electrostatic latent image corresponding to the black image on the photoreceptor belt 1 is developed by the black developing device 7 moved to the developing position, and a black monochromatic image is formed. The single-color images formed on the photoconductor belt 1 are sequentially superimposed and transferred onto an intermediate transfer belt 10 that rotates counterclockwise while contacting the photoconductor belt 1. Yellow, magenta, superimposed on the intermediate transfer belt 10
The cyan and black images are transferred by the transfer roller 14 to the transfer paper conveyed to the transfer unit from the paper supply cassette 17 via the paper supply roller 18, the conveyance roller 19, and the registration roller 20. After the transfer is completed, the transfer paper is fixed by the fixing device 49 to complete a full-color image.

Next, FIG.
A description will be given based on FIG. As the device body structure,
It comprises a main body frame 9 as an immovable part housing and a front frame 8 as a front housing capable of opening a transfer paper transport path. A paper feed cassette 17 is arranged below the main body frame 9, a color developing unit 6, a black developing device 7, and a process cartridge 31 are exchangeably arranged at a central portion, and a fixing device 49 is arranged above the exchangeable unit.
A discharge stack portion is formed.

The front frame 8 is supported so as to be rotatable about a rotation support shaft 9A provided on a main body frame 9 serving as a rotation fulcrum.
Are held by the main body frame 9 as shown in FIG. By releasing the holding during the jam processing, the opening can be opened in the clockwise direction in FIG. 5, and the open state can be maintained by the power of a tension spring or the like. The front frame 8 holds a registration roller 20, a transfer roller 14, and the like, which are parts of the transport path. As a result, when the front frame 8 is opened, the transport path is opened as shown in FIG. 5, and the paper jam processing is performed. At this time, since only the jam processing can be performed without operating the image forming system unit such as the developing unit 6, there is no problem such as toner drop.

Further, the process cartridge 31 is held on the main body frame 9 in a configuration described later, and is supported so as to be rotatable about a rotation support shaft 9B provided on the main body frame 9 serving as a rotation fulcrum. The intermediate frame 40 is provided on the near side and the far side in FIG. 5 (see FIG. 6). The intermediate frame 40 is normally held (other than when the process cartridge 31, the color developing unit 6 or the black developing device 7 is replaced) by the main body frame 9. As shown, it can be opened clockwise.

FIG. 7 shows the attachment / detachment position of the process cartridge 31, and FIGS. 8 (a) to 8 (c) show the attachment / detachment state of the process cartridge 31. Rail-shaped projections 32 are provided on both side surfaces of the process cartridge 31 so as to be parallel to the attaching / detaching operation direction. Correspondingly, the rail-shaped grooves 4 are similarly formed on the intermediate frame 40 so as to be parallel to the attaching / detaching operation direction.
0A is provided so that the intermediate frame 4
0 holds the process cartridge 31. If the process cartridge 31 is operated in the direction of the arrow while the intermediate frame 40 is supported and fixed at the position shown in FIG. 7, the process cartridge 31 can be more easily attached and detached than the intermediate frame 40. In particular, when the handle 33 is provided at the front of the process cartridge 31, the operability is further increased. The groove 40
As for the shape of A, if the insertion side of the process cartridge 31 is opened like a trumpet, a slight displacement can be mounted without any problem.

Here, the operation direction of the process cartridge 31 is the direction in which the two rollers 11 and 12 of the intermediate transfer belt 10 are stretched, and the belt surface on which the photosensitive belt 1 is stretched is the intermediate transfer belt. Since it is arranged so as to be substantially parallel to the surface, the space between development and transfer can be reduced, and the cross section of the apparatus main body can also be reduced.

The intermediate frame 40 can be further opened to the mounting / detaching position of the process cartridge 31, and reaches the same position as the opening position of the front frame 8 as shown in FIG. At this position, the intermediate frame 40 is supported and fixed while the process cartridge 31 is mounted, so that the process cartridge 31 does not have to be once moved out of the apparatus main body, and the color developing unit 6 disposed behind the process cartridge 31 can be used. Also, since the black developing device 7 is greatly opened, the operability of attaching and detaching them becomes a good source.

FIGS. 8A to 8C show an example of a mechanism for supporting and fixing the intermediate frame 40 in two stages. 8, two grooves are provided below the rotation fulcrum of the intermediate frame 40, and the leaf spring 34 is incorporated in the main body frame so as to swing with a constant spring force in the direction of the arrow. The leaf spring swinging distal end portion 34A is
The intermediate frame 40 is latched and supported and fixed in two stages by rotating the intermediate frame 40 into the grooves 40B and 40C. At this time, the position of the process cartridge 31 in the attaching / detaching rotational direction is supported and fixed at a position such that the center of gravity G of the process cartridge 31 is substantially on the vertical line of the rotational center position of the intermediate frame 40, and the attaching / detaching moving direction is substantially vertical. By adjusting the handle position so that the process cartridge 31 is supported and fixed, the spring force of the leaf spring 34 for supporting and fixing the process cartridge 31 is minute, the stability at the time of the rotation operation of the intermediate frame 40 is obtained, and the process cartridge becomes gravitational. Can be operated without falling into an unstable state. In addition, if the intermediate frame 40 is used as a stopper member for stopping rotation by using a part of the front frame at the second support fixing position, the groove 40C of the intermediate frame 40 can be eliminated.

Next, based on FIGS. 1 and 10, the structure of a case member for positioning and mounting the color developing unit 6 and the black developing unit 7 on the main body frame 9 in the color image forming apparatus having the above configuration. Will be described. As shown in FIGS. 1 and 10, the color developing unit 6 has a shape incorporated in a case member 101, and the entire color developing unit with the case member 101 integrated with the main body frame 9. It can be attached and detached. Both ends of the rotating shaft of the inner casing 21 as a rotating body of the color developing unit 6 are provided with rotation reference holes 101A formed in side walls of both ends of the case member 101 in the longitudinal direction (the rotating shaft direction of the inner casing 21). Is mounted so as to be rotatable.

The side walls of both ends of the case member 101 in the color developing unit 6 in the longitudinal direction are formed with cylindrical projections 10.
1B. By being supported by the main body side plate 102 of the main body frame 9 at three points (P1, P2, and P3 in FIG. 1) of the convex portion, the main body side plate 102
The color developing unit 6 is positioned with respect to and is fixed by a stopper member (not shown). On the other hand, when the process cartridge 31 is mounted on the main body frame 9, the end of the rotating shaft of the rotating roller 2 on the lower side of the photoreceptor belt 1 is attached to the main body side plates 102 on the near side and the back side in FIG. While being received and supported by the receiving portion 102A, the rotation shaft end of the rotation roller 11 above the intermediate transfer belt 10 is
Each main body side plate 102 is received and supported by a receiving portion 102B. By supporting the process cartridge 31 in this way, the photosensitive belt 1 is positioned with respect to the main body side plate 102. As described above, by positioning the color developing unit 6 and the photosensitive belt 1 with respect to the main body side plate 102, the photosensitive belt 1
The color developing unit 6 is positioned with respect to
The developing roller 23 at the developing position of the unit faces the surface of the photoreceptor belt 1 at a predetermined gap or nip width.

The photosensitive belt 1 of the black developing device 7
Is performed by fixing the black developing device 7 at a predetermined position of the case member 101 of the color developing unit 6 positioned as described above. As shown in FIG. 1, on the lower surface of the developing container 41 of the black developing device 7, a projection 41A positioned on the upper surface of the case member 101 of the color developing unit 6 and the photosensitive belt 1 of the black developing device 7 are provided.
A convex guided portion 41B that is guided by the upper surface of the case member 101 when moving toward and away from is formed.
As shown in FIG. 10, the upper surface of the case member 101 of the color developing unit 6 has a slightly lowered surface on the side of the photoreceptor belt 1 and engages with the protrusion of the black developing device 7 on this surface. An engaging hole 101C is formed as a positioning portion for positioning. That is, this engagement hole 10
An edge surface of the photoconductor belt 1C on the side of the photoreceptor belt 1 (a surface on which the protrusion 41A abuts) serves as a positioning reference surface of the black developing device 7 in the X direction in the drawing. Further, Y of the engagement hole 101C in the drawing is shown.
The width in the direction is set so that the black developing device 7 has a thrust play. By moving the black developing device 7 toward the photoreceptor belt 1 with the black developing device 7 placed on the color developing unit 6, the protrusion 41A is brought into contact with the edge of the engaging hole 101C and positioned at a predetermined developing position. The developing roller 23 of the black developing device 7 comes to face the surface of the photoreceptor belt 1 at a predetermined gap or nip width.

Further, on the upper surface of the case member 101 of the color developing unit 7, the guided portion 4 of the black developing device 7 is provided.
1B so that the guided portion 4 can engage and slide.
A guide hole 101D for guiding 1B is formed.
The guided portion 41B of the black developing device 7 is
While being guided by D, the black developing device 7 moves the color developing unit between the developing position where the protrusion 41A abuts the edge of the engagement hole 101C and the non-developing position which is separated from the developing position as described above. 6 can be slid. The black developing device 7 is urged to the non-developing position side by a spring as urging means (not shown), and the movement of the black developing device 7 toward the photoreceptor belt 1 starts from the left side of FIG. This is performed by a cam member (not shown) that presses the side end surface.

The lower part of the case member 101 of the color developing unit 6 has a stand so that the unit 6 can stand on its own when placed on a flat surface outside the apparatus. The stand portion is provided with the developing opening 101 of the case member 101.
A unit supporting side plate 101F extending vertically downward from the lower edge of E, and a unit supporting leg 101G extending vertically downward from the rear side of the unit 6 opposite to the developing opening 101E. It is configured. The unit support side plate 101F and the unit support leg 101G are provided over the entire width in the unit longitudinal direction. The unit supporting side plate 101F is provided between the space adjacent to the developing opening 101E and the optical window material 5 of the laser writing unit 5.
It is also used as a shielding member for shielding the space adjacent to the exposed surface of F.

The lower end of the unit supporting side plate 101F is
The bent portion 101H is bent inside the unit, and the bent portion 101H is
It is in contact with the upper surface end of the unit case 5E of the laser writing unit 5 through the line 03. This bent portion 101
The dimension of H is set to a minimum necessary to be received by the cushion member 103.

The laser light emitted from the optical window member 5F of the laser writing unit 5 located below the color developing unit 6 is moved in the vicinity of the lower end of the developing opening 101E to the rotating roller of the photosensitive belt 1. 2 towards the wrap around. Therefore, the unit supporting side plate 10
A light through hole 101I for passing a laser beam is formed in the vicinity of the developing opening 101E of 1F. This light through hole 10
At the lower end of the developing opening 101E above 1I, an eave 101J extending horizontally toward the photoreceptor belt 1 over the entire width in the longitudinal direction is provided, and the toner scattered from the developing opening 101E is provided by the eave 101J. Light through hole 10
I try not to fall toward 1I. An eave 101L is formed above the developing opening 101E over the entire width in the longitudinal direction.

Further, the lower end of the unit support leg 101G has a flat portion, and this flat portion is in contact with the upper surface of the unit case 5E of the laser writing unit 5 via the cushion member 104. Unit support leg 1
A dustproof filter 105 is housed inside 01G, and an exhaust port 101K is formed on the back surface. An exhaust fan (not shown) connected to the exhaust port 101K exhausts air in the color developing unit 6 to the outside of the color developing unit 6 through the dustproof filter 105.
From 01E, the toner is prevented from scattering into the apparatus main body.

As described above, according to the present embodiment, the color developing unit 6 is positioned with respect to the photoreceptor belt 1, and the black developing device 7 placed above the color developing unit 6 is moved to the color developing unit. Case member 10 of unit 6
1, the black developing device 7 is positioned relative to the photosensitive belt 1 so that the gap or nip width between the developing roller 23 and the photosensitive belt 1 is constant. Indirect positioning. Accordingly, the size of the image forming apparatus main body can be reduced as compared with the case where the positioning member of the black developing apparatus 7 is provided on the apparatus main body side, and the developing performance of the color developing unit 6 and the black developing apparatus 7 can be stabilized. Can be achieved.

According to the present embodiment, the black developing device 7
Is guided between the developing position and the non-developing position by using the guide holes 101D provided on the upper surface of the case member 101 of the color developing unit 6, so that the The size of the image forming apparatus main body can be reduced as compared with the case where the guide portion is provided.

Further, according to the present embodiment, the toner scattered from the developing openings of the color developing unit 6 and the black developing device 7 and falling vertically downward is applied to the lower end of the developing opening 101E of the case member 101. Of the developing window 10F through the light through hole 101I formed in the unit supporting side plate (shielding member) 101F extending vertically downward from the optical window member 5F.
The eaves 101J provided so as to extend from the lower end of 1E to the photoreceptor belt 1 side catches the developer scattered from the developing opening, thereby making it difficult to drop toward the light through hole 101I. , Window material made of toner 5
The occurrence of dirt on the exposed surface of F can be prevented.

Further, according to the present embodiment, when the rotary type color developing unit 6 having three developing units supported by the inner casing 21 is detached from the image forming apparatus main body and placed outside the apparatus, the developing unit 6 Unit supporting side plate 101F and unit supporting leg 10 provided on case member 101 of FIG.
1G allows the developing unit 6 to be self-supporting, thereby preventing the developing unit 6 from tipping over and protecting the developing unit 6 from damage due to tipping.

In the above embodiment, the image forming apparatus employing the intermediate transfer system using the intermediate transfer belt 10 has been described. However, the present invention employs a system in which four colors are superimposed on the photosensitive belt 1. The same can be applied to an image forming apparatus.

[0051]

According to the first to fourth aspects of the present invention, another developing device adjacent to the reference developing device is positioned using the positioning portion provided in the reference developing device positioned with respect to the image carrier. Thus, since the gap or the nip width between the developer carrier and the image carrier of another developing device is indirectly positioned with respect to the image carrier, the development in each developing device is It is possible to stabilize the performance and to secure a space for providing the positioning portion between the two developing devices without increasing the distance between the reference developing device and the other developing device. There is an effect that the size of the image forming apparatus main body can be reduced as compared with the case where the positioning member is provided on the main body side.

In particular, according to the second aspect of the present invention, the movable developing device is guided by the guide portion provided in the developing device adjacent to the movable developing device, so that the developing position facing the image carrier and the developing position The movable developing device can be moved between the movable developing device and the adjacent developing device without increasing the space between the movable developing device and the adjacent developing device. Thus, there is an effect that the size of the image forming apparatus main body can be reduced as compared with the case where the guide portion is provided on the image forming apparatus main body side.

According to the third aspect of the present invention, a shield for shielding a space adjacent to the developing opening of the lowermost developing device and a space adjacent to the exposed surface of the light emitting optical member of the light irradiation device. The member makes it difficult for the developer scattered from the developing opening to drop vertically downward into the space adjacent to the exposed surface of the light emitting optical member. Further, since the light through hole through which the light from the light irradiation device penetrates is formed in the shielding member extending vertically downward from the lower end of the developing opening, the developing material which falls vertically downward from the developing opening is formed. The agent is less likely to enter the space adjacent to the exposed surface of the light emitting optical member. Further, an eave provided so as to extend in the horizontal direction from the lower end of the developing opening toward the image bearing member catches the developer scattered from the developing opening and drops toward the light through hole. This makes it possible to prevent the developer from being stained on the exposed surface of the light-emitting optical member by the developer.

According to the invention of claim 4, when the rotary developing device in which a plurality of developing devices are supported by the rotary support is detached from the image forming apparatus and placed outside the device, the rotary developing device can be used. Since the developing device can be made to stand on its own by the stand provided on the case member, there is an effect that the developing device is prevented from overturning and the developing device can be protected from damage due to overturning.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration near a color developing unit of a color image forming apparatus according to an embodiment.

FIG. 2 is a sectional view showing a schematic configuration of the entire color image forming apparatus.

FIG. 3 is a sectional view showing an internal structure of a color developing unit and a black developing device of the color image forming apparatus.

FIG. 4 is a perspective view of a color developing unit of the color image forming apparatus.

FIG. 5 is a sectional view of the color image forming apparatus in a state where a front frame is opened.

FIG. 6 is a perspective view of a process cartridge of the color image forming apparatus and an intermediate frame for supporting the process cartridge.

FIG. 7 is a cross-sectional view showing a mounting / dismounting position of the process cartridge.

FIGS. 8A to 8C are side views showing a detached state of the process cartridge.

FIG. 9 is a sectional view of the color image forming apparatus in an opened state of an intermediate frame.

FIG. 10 is a perspective view of a case member of the color developing unit of the color image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor belt 2, 3 Rotating roller 4 Charging charger 5 Optical writing unit 5F Optical window material 6 Rotary color developing unit 7 Black developing device 8 Front frame 9 Main body frame 10 Intermediate transfer belt 15 Cleaning unit for photoconductor belt 16 Cleaning Unit for Intermediate Transfer Belt 21 Inner Casing 22 Developing Device 23 Developing Roller 31 Process Cartridge 35 Backup Roller 41 Developing Container 41A Projection 41B Guided Part 101 Case Member 101A Rotation Reference Hole 101B Convex 101C Mating hole 101D Guide hole 101E Developing opening 101F Unit supporting side plate (shielding member) 101G Unit supporting leg 101H Bending portion 101I Light through hole 101J Eave 101K Exhaust port 101L Eave 102 Body side plate 02A, 102B receiving portion 103, 104 cushion member 105 dust filter

Claims (4)

[Claims] An image forming apparatus provided with a plurality of developing devices opposed to the image carrier, wherein the reference developing device is mounted on a case member of a reference developing device positioned with respect to the image carrier among the plurality of developing devices. An image forming apparatus, comprising: a positioning portion for positioning another developing device adjacent to the device with respect to the image carrier. 2. An image according to claim 1, wherein said developing device comprises a movable developing device which is movable between a developing position facing said image carrier and a position separated from said developing position. An image forming apparatus, wherein a guide portion for guiding the movement of the movable developing device is provided in a case member of the developing device adjacent to the movable developing device. 3. The developing device according to claim 1, wherein the plurality of developing devices are arranged side by side in a vertical direction, and a developing opening for exposing a developer carrier of the lowermost developing device is provided on a side portion of the lowermost developing device. 2. The image forming apparatus according to claim 1, further comprising: a light irradiating device that forms a latent image by irradiating light passing through the vicinity of the developing opening to the surface of the image carrier below the lowermost developing device. A shielding member extending vertically downward from a lower end of the developing opening is provided so as to shield a space adjacent to the developing opening and a space adjacent to an exposed surface of the light emitting optical member of the light irradiation device. Forming a light through hole through which light emitted from the light emitting optical member of the light irradiation device passes through the shielding member, and extending an eave extending horizontally from the lower end of the developing opening toward the image carrier. An image forming apparatus, comprising: 4. The image forming apparatus according to claim 1, wherein said developing device comprises a rotary developing device in which a plurality of developing devices are supported by a rotary support. An image forming apparatus provided with a stand for making a mold developing device stand alone.