JP2000003092A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of reducing the breakage of each developing roller and toner scattering of a turning type developing device caused by a warpage and distortion of a cover member. SOLUTION: Rib shaped members 401 and 402 extended in the axial direction of a turning shaft O are provided at the upper part of a cover member 41, that is, the part of the member 41 opposed to a black developing device. Furthermore, a 2nd rib-shaped member 403 is laid on the members 401 and 402 so that it may orthogonally cross with the members 401 and 402 and its upper part may be in parallel with the attaching/detaching direction of the black developing device.

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 improvement of a cover member that covers a plurality of developing units of a rotary developing device.

[0002]

2. Description of the Related Art Conventionally, a color separation light image is exposed to a latent image carrier, each formed latent image is developed with a toner of a complementary color of the color separation light, and a plurality of obtained toner images are formed on the same transfer paper. A full-color image forming apparatus such as a full-color copying machine that transfers images by superimposing them onto a latent image carrier that is to be reproduced in different colors, and developing each latent image in a different color. There is known a multicolor image forming apparatus which develops a plurality of toner images and transfers the obtained toner images by superimposing them on the same transfer paper. In these image forming apparatuses, a plurality of developing units are required to perform development of a plurality of colors. However, if each developing unit is independently configured and arranged side by side around the latent image carrier, the size of the apparatus increases. There was a disadvantage that it would.

[0003] Therefore, conventionally, a rotating body is provided opposite to the latent image carrier, and a plurality of developing devices are supported by the rotating body at predetermined positions, and each developing device is mounted on the latent image carrier. Many rotary developing devices have been proposed in which a latent image on a latent image carrier is developed with each color toner by sequentially rotating and transporting the latent image to an opposing developing position.

For example, Japanese Patent Publication No. Hei 4-23782 and Japanese Patent Application Laid-Open No. Hei 4-29166 disclose an image forming method in which a rotary developing device is integrally detached and replaced when a toner end of one developing unit occurs. An apparatus is described. However, in this type of image forming apparatus, since the rotary developing device is integrally replaced, the developing device containing a sufficient amount of toner is also replaced, so that there is much waste and the running cost is greatly reduced. Was causing a significant rise. For example, when handling a normal general document, the output of a black-and-white image is mainly performed, and the ratio of the black-and-white output image to the color output image is 9: 1.
Is said to be 7: 3. For this reason, the consumption of the black toner is overwhelmingly larger than the consumption of the non-black toner, and a large amount of the non-black toner is wasted. Also,
It is time to replace the rotary type developing device at the time of toner end, and it is necessary to discard members whose life has not expired. Furthermore, from the viewpoint of protecting the global environment, a system and equipment for collecting, disassembling and recycling the rotary developing device made of various materials are required, which substantially raises initial costs and running costs. Become.

In Japanese Utility Model Publication No. 4-38362, there is described an image forming apparatus having a rotary developing device for storing a large amount of black toner which consumes a larger amount than a non-black toner. In this type of image forming apparatus, Japanese Patent Publication No. 4-237
As compared with the image forming apparatus described in JP-A-82-82 and JP-A-4-29166, waste of non-black toner is reduced, and an increase in running cost is reduced. However, there is a variation in the consumption amount of each color toner, and it has not completely prevented wasteful disposal of toner. In addition, similar to the image forming apparatus disclosed in Japanese Patent Publication No. Hei 4-23782 and Japanese Patent Laid-Open Publication No. Hei 4-29166, the initial costs and the running costs are substantially increased.

Further, Japanese Patent Application Laid-Open No. 61-97674 and Japanese Patent Publication No. 6-5403 disclose a plurality of toner cartridges which are fixed to a main body of the apparatus and contain toner of a predetermined color. An image forming apparatus having a flexible tube member for individually connecting each developing unit of the developing device and each corresponding toner cartridge is described. In this type of image forming apparatus, a predetermined color toner can be supplied to each developing unit by rotating a toner conveying member provided inside the flexible tube member in accordance with consumption of toner. However, in order to prevent the flexible tube member and the toner conveying member from being twisted, a connection that opens a connection state between each developing device and each flexible tube member according to a rotation state of the rotary developing device. Parts need to be provided. Further, it is necessary to provide a shutter and a seal member at the connecting portion in order to prevent scattering and leakage of the toner at the connecting portion and mixing of toners of other colors. There is a problem that the initial cost of the system increases.

Japanese Patent Publication No. 7-43551 discloses an image forming apparatus having a toner supply means provided at one end of a rotary developing device and a slider for slidably supporting the rotary developing device. Has been described. This type of image forming apparatus has an advantage that a toner of a predetermined color can be supplied to each developing unit without having the above-mentioned connecting portion. However, cleaning, inspection, adjustment, repair, and replacement of each component in the rotary developing device, and when a two-component developer is used, periodic replacement of the carrier is required. That is, the operator does not have to perform only the toner replenishment, but requires periodic maintenance of the rotary developing device. For this reason, in the image forming apparatus of Japanese Patent Publication No. 7-43551, the slider is provided to improve operability in maintenance work. However, the initial cost of the apparatus main body has been increased due to the complicated and robust configuration of the slider. In addition, when one of the developing devices reaches the end of its life, it is necessary to replace the entire rotary developing device, which greatly increases the running cost. For example, as described above, the consumption amount of the black toner is overwhelmingly higher than the consumption amount of the non-black toner, and, of course, the developing device for black is used much more frequently than the developing device for non-black. . For this reason,
If the black developing device and the non-black developing device have the same durability, the black developing device will reach its life earlier than the non-black developing device. Therefore, when a developing device for black is provided in the rotary developing device, high reliability and high maintainability of the developing device for black are required.

Further, JP-A-60-208779, JP-A-60-214377, JP-A-61-73163,
Japanese Patent Application Laid-Open No. S61-103175 discloses an image forming apparatus in which individual developing units of a rotary developing apparatus are configured as disposable systems called developing cartridges or developing magazines. According to this type of image forming apparatus, for example, JP-A-60-208779 and JP-A-6-208779
As described in JP-A No. 1-103175, by rotating an arbitrary developing device to a predetermined replacement position during maintenance work or replacement of the developing device, only the arbitrary developing device is rotated. It can be removed from the device. However, in this type of image forming apparatus, it is necessary to provide independent side plates and casings for each developing device of the rotary developing device, and further to provide a support member for supporting each developing device. There was a limit to miniaturization and cost reduction. In addition, since each developing device is handled individually, there is a problem that when the maintenance work of a plurality of developing devices is performed sequentially, the maintenance work requires time and effort. For example, in the case of a non-black developing device, although the amount of toner consumption varies slightly depending on the color of the toner to be handled, the frequency of use is almost the same and the life often ends at the same time. Often exchanged at the same time.

Further, as a rotary type developing apparatus, and thus an image forming apparatus as a whole, the size of which is reduced, and a frequently used monochrome image output is maintained in a stable and high quality, for example, Japanese Patent Publication No. 59-26954. No., JP-A-60-
233669, JP-A-62-85266, JP-A-6-85266
2-102261, Japanese Utility Model Application Laid-Open No. 63-26847,
JP-A-63-41871 and the like. This type of image forming apparatus is provided singly around a photoreceptor as a latent image carrier and forms a black image image with a black toner, and a developing device different from the black developing device. And a rotating developing device having a plurality of developing units that sequentially rotate to a position and form an image of a predetermined color with toner of a predetermined color. According to this type of image forming apparatus, it is possible to separately handle a frequently used black developing device and a relatively infrequently used non-black developing device,
Operability in maintenance work of the black developing device can be improved. However, depending on the configurations of the black developing device and the rotary developing device, various problems may occur. For example, Japanese Patent Application Laid-Open No.
In the image forming apparatus of No. 9, it is necessary to provide independent side plates and casings for the three developing devices supported by the rotary developing device, and further to provide support members for supporting the three developing devices, respectively. There is a limit in reducing the size and cost of the rotary developing device. In addition, since the above three developing devices are individually handled, there is a problem that when the maintenance work of these developing devices is performed sequentially, the maintenance work requires time and effort.

Therefore, the present inventor has disclosed in Japanese Patent Laid-Open No. 9-114.
No. 179, the above-mentioned black developing device is constituted by a developing cartridge, and a plurality of non-black developing devices provided in the rotary developing device are replenished with toner of a predetermined color according to the amount of consumed toner. An image forming apparatus having such a configuration is proposed. According to this image forming apparatus, the operability of the frequently used black developing device is improved, and the image forming apparatus is also suitable for a plurality of non-black developing devices having the same usage frequency and different toner consumption. Can be handled. Further, a toner replenishing device is provided at one end of the rotary type developing device so as to convey toner in the axial direction of the rotary shaft. The size can be reduced, and the degree of freedom in layout inside the image forming apparatus can be increased. However,
This image forming apparatus does not include a member for protecting the peripheral surface of the rotary developing device. For this reason, when the black developing device is attached or detached, each developing roller inside the rotary developing device is damaged, toner is scattered from each developing device, and the inside of the device main body is contaminated. There is a possibility that the black toner scatters from the developing device to cause a color mixture of the black toner to each developing device.

On the other hand, the present inventor has previously described Japanese Patent Application No. 8-35.
No. 3663, a cylindrical cover member having an opening at a developing position facing a latent image carrier is provided on the peripheral surface of the rotary developing device, and a handle member capable of being tightly housed is provided on the outer peripheral portion of the cover member. Proposed an image forming apparatus. According to this image forming apparatus, the problem of the image forming apparatus described in Japanese Patent Application Laid-Open No. Hei 9-114179 can be solved by installing the cylindrical cover member.

[0012]

However, in the image forming apparatus described in Japanese Patent Application No. 8-353636, if the strength of the cover member is insufficient, for example, when the black developing device is attached and detached. When an external force is applied to the cover member by contact with the cover member, deformation of the cover member may damage the developing roller and the like of each developing device of the rotary developing device. Further, when a resin molded product is used for the cylindrical cover member, for example, warpage or distortion is likely to occur during molding and processing. The warping and distortion may damage the developing roller of each developing device,
The toner on the developing roller may be scattered.

The present invention has been made in view of the above background, and an object of the present invention is to reduce damage to each developing roller and toner scattering of a rotary developing device due to warpage or distortion of a cover member. It is an object of the present invention to provide an image forming apparatus capable of performing the above.

[0014]

To achieve the above object, the present invention is directed to a latent image carrier for forming a latent image on a surface thereof and a plurality of developing devices arranged around a rotation axis. A rotary developing device having a developing device, and a cover member having an opening at a developing position facing the surface and covering the plurality of developing devices, the rotary developing device having the rotary shaft as a center. In the image forming apparatus which develops the latent image by moving an arbitrary developing device to the developing position by turning, the rib shape extending in the axial direction of the turning shaft is formed on the cover member. Is what you do.

According to a second aspect of the present invention, in the image forming apparatus of the first aspect, the color separation latent image corresponding to black is opposed to the latent image carrier at a development position different from the development position and the black developer A second developing device for developing the developing device is detachably disposed above the rotary developing device, and the individual color developing units of the rotary developing device correspond to a predetermined color other than black. The image is successively developed with the developer of the predetermined color.

In the first or second aspect of the present invention, the rib shape enhances the strength of the cover member in the axial direction and reduces deformation of the cover member such as warpage and distortion.

According to a third aspect of the present invention, in the image forming apparatus of the first or second aspect, the second rib shape is formed so as to extend in a direction different from the axial direction with respect to the rib shape. It is assumed that.

In the invention according to claim 3, the second rib shape further increases the strength of the cover member in the axial direction, and also increases the strength in a direction different from the axial direction. That is, the second rib shape further increases the strength of the cover member, and further reduces deformation of the cover member such as warpage and distortion.

According to a fourth aspect of the present invention, there is provided the image forming apparatus according to the third aspect, wherein the second developing device that moves in the attaching / detaching direction includes:
It is characterized by being supported on the upper part of the cover member.

According to the fourth aspect of the present invention, the upper portion of the cover member can be used as a guide for attaching and detaching the first developing device.

According to a fifth aspect of the present invention, in the image forming apparatus of the fourth aspect, the second rib shape is formed in a direction parallel to the attaching / detaching direction, and the second developing device moving in the attaching / detaching direction is provided in the second developing device. It is characterized by being supported in a two-rib shape.

In the fifth aspect of the present invention, the surface of the second rib shape on the side of the first developing device is used as an operation guide for attaching and detaching the first developing device. Accordingly, it is not necessary to newly provide a member for causing the upper part of the cover member to function as an operation guide for attaching and detaching the first developing device.

According to a sixth aspect of the present invention, in the image forming apparatus according to the fourth aspect, a planar shape is formed on the upper portion of the cover member, and the second developing device moving in the attaching / detaching direction is supported by the planar shape. It is characterized by the following.

According to the sixth aspect of the present invention, the planar shape makes it easier for the operator to recognize the upper portion of the cover member as an operation guide for attaching and detaching the first developing device.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an example of a conventional color image forming apparatus having a cover member on the peripheral surface of a rotary developing device will be described. FIG. 1 is a schematic configuration diagram of an entire color image forming apparatus having the above-described conventional configuration. In FIG. 1, a flexible belt-shaped photoreceptor (hereinafter, referred to as a “photoreceptor belt”) 1 as an image carrier is provided between rotating rollers 2 and 3, and the driving of the rotating rollers 2 and 3 is performed. As a result, it is rotated and transported in the direction of arrow A (clockwise) in the figure. Around the photoreceptor belt 1, a charging charger 4 as a charging unit for uniformly charging the surface of the photoreceptor belt, a laser writing unit 5 as an exposure device for forming an electrostatic latent image, yellow, magenta, and cyan A rotary color developing unit (hereinafter referred to as a "color developing device") as a rotary developing device (also referred to as "revolver type" or "rotary type") integrally provided with three developing devices each containing a color developer. unit"
And a black developing device 7 as a developing device containing a black developer separate from the color developing unit 6.

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. Paper cassette 17
A bottom plate (not shown) is provided between and the laser writing unit 5. A laser writing unit 5 is incorporated on the bottom plate, and side plates (not shown) of the apparatus main body provided on the left and right (rear side and front side in FIG. 1) in the roller axis direction to support each unit correspond to the bottom plate. Has been assembled.

The charging position by the charger 4, the irradiation position of the light beam L from the laser writing unit 5, and the cleaning position by the photosensitive member cleaning blade 15 A are lower than the two rotating rollers 2 and 3. Is set at a portion where the photosensitive belt 1 is wound around the rotating roller 2 on the side.

The color developing unit 6 and the black developing device 7 each have a developing roller as a developer carrying member which comes close to or comes into contact with the photosensitive belt 1 at a predetermined position. Has a function of visualizing by a non-contact development or a contact development method. In addition,
The color developing unit 6 and the black developing device 7 will be described later in detail.

Rotating roller 3 above photoreceptor 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 rotating rollers 11 and 12, and is rotated and conveyed in the direction of arrow B (counterclockwise) in the figure by driving the rotating 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 conductive bias brush 13 as a primary transfer member provided inside the intermediate transfer belt 10 (primary transfer). The tip of the bias brush 13 is in contact with the back surface of the intermediate transfer belt 10 under predetermined conditions. The intermediate transfer belt 10 is wound around the rotation roller 11 at the intermediate transfer belt 10.
A transfer roller 14 as a secondary transfer member is provided so as to come into contact with and separate from the transfer roller 14, and the image superimposed on the intermediate transfer belt 10 is transferred onto a transfer paper as a transfer material by the transfer roller 14 (2). Next 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.

Cleaning device 15 for photosensitive belt
Is a cleaning blade 15A that constantly contacts the photoconductor belt 1 and cleans the toner on the photoconductor belt 1;
A waste toner collecting container 15B and the like are provided. The cleaning device 16 for the intermediate transfer belt includes a cleaning blade 16A for cleaning the surface of the intermediate transfer belt 10, an auger 16B for conveying the toner, and the like.
The cleaning blade 16A for the intermediate transfer belt is kept at a position separated from the surface of the intermediate transfer belt 10 during image formation, and abuts on the surface of the intermediate transfer belt 10 as shown only during cleaning after the secondary transfer. Is done.

In the above-structured color image forming apparatus,
After the photoconductor belt 1 is uniformly charged by the charging charger 4, the laser beam (laser beam) L modulated based on image information is scanned by the laser writing unit 5 to be exposed, and the surface is electrostatically charged. A latent image is formed. Here, the image information used for the exposure is monochromatic image information obtained by decomposing a desired full-color image into yellow, magenta, cyan, and black color information. Laser light L generated by a semiconductor laser (not shown) based on this image information
Is rotationally scanned by a polygon mirror 5B rotated at high speed by a drive motor 5A, passes through an f-θ lens 5C,
The optical path is adjusted by the reflection mirror 5D.

The electrostatic latent image formed on the photoreceptor belt 1 is developed by a later-described color developing unit in a single color with predetermined yellow toner, magenta toner, and cyan toner, respectively. Further, the electrostatic latent image formed based on the black color information is developed with black toner by a black developing device 7 to be described later, and each color image (toner image) is sequentially formed on the photosensitive belt 1. You.

Each monochrome image (toner image) formed on the photosensitive belt 1 rotating in the direction of arrow A in FIG. 1 is applied to the bias brush 13 for each of the single colors of yellow, magenta, cyan, and black. Due to the predetermined transfer bias, the image is sequentially transferred onto the intermediate transfer belt 10 rotating in the direction of arrow B in synchronization with the photosensitive belt 1. Intermediate transfer belt 1
The images of yellow, magenta, cyan, and black superimposed on the image No. 0 are transferred from a sheet feeding table (sheet feeding cassette) 17 through a sheet feeding roller 18, a pair of conveying rollers 19A and 19B, and a pair of registration rollers 20A and 20B. Is collectively transferred by the transfer roller 14 onto the transfer paper 17 </ b> A conveyed to the printer. After the transfer, the image is fixed by the fixing device 80 to complete the full-color image. Transfer paper 1 on which this full-color image is formed
7A is discharged to a discharge stack 82 via a pair of discharge rollers 81A and 81B.

The photoreceptor belt 1, charging charger 4,
The intermediate transfer belt 10, the cleaning device 16, the registration roller 20B, and the like are integrally formed as a process cartridge, and the waste toner collecting container 15C is detachably attached to the process cartridge 31. The case exterior part of the registration roller 20B of the process cartridge 31 also has a function as a paper conveyance guide.

The waste toner scraped off the intermediate transfer belt 10 by the cleaning blade 16A is
The toner is conveyed toward the front of the drawing by an auger 16B provided in the cleaning device 16, and further conveyed to a waste toner collecting container 15C by a conveyance unit (not shown) provided on the front side surface of the process cartridge 31. By replacing the process cartridge 31 when a predetermined amount or more of waste toner is stored in the waste toner collecting device 15C, the life of the process cartridge 31 can be extended.

Next, the black developing device 7 used in the present color image forming apparatus will be described. FIG. 2 shows a black developing device 7.
1 is a schematic configuration diagram showing the inside of the device together with a color developing unit 6. The black developing device 7 contains a black developer (toner) in a developing container 71, and has a developing roller 23 </ b> K as a developer carrier in an opening 71 </ b> A of the developing container 71 facing the photoreceptor belt 1. This is a developing device integrally formed as a so-called developing cartridge in which the life of the developing device is replaced when the toner runs out.

In the developing container 71, a developing roller 23 is provided.
Parallel to K, and contacts the developing roller 23K at a predetermined contact pressure, and rotates so as to slide in a direction opposite to the developing roller surface moving direction at a contact portion with the developing roller 23K while forming a nip. For example, a toner supply roller 25K made of foamed polyurethane or the like is provided. In the vicinity of the opening 71A downstream of the sliding portion between the toner supply roller 25K and the developing roller 23K in the direction of movement of the developing roller surface, a toner layer regulation made of a springy thin plate such as stainless steel or an elastic material such as urethane rubber. A blade 26K as a member has a developing roller 23 near one end thereof.
It is provided so as to be in contact with K.

In the developing container 71, a first agitator 73 for stirring the toner in the container and transporting the toner to the toner supply roller 25K and the developing roller 23K is provided.
The second agitator 7 also stirs the toner in the developing container 71 and conveys the toner to the first agitator 73 side.
4 are provided. The first and second agitators 73 and 74 are disposed such that each rotation axis is parallel to the toner supply roller 25K and the developing roller 23K. Both agitators 73 and 74 are provided with a film-like elastic sheet or the like at the tip thereof so that the tip thereof slides on the bottom surface of the developing container 71.
The toner in the developing container 71 can be efficiently transported, and the remaining amount of the toner in the developing container 71 can be reduced. It is desirable that the rotation speed of the agitators 73 and 74 be as low as possible so as not to apply extra stress to the toner.

The black developing device 7 is movable in the horizontal direction with respect to the photoreceptor belt 1, is separated from the photoreceptor belt 1 during non-development, and the developing roller 23 approaches or contacts the photoreceptor belt 1 during development. A separating operation for moving to the developing position is performed. Normally, the black developing device 7 is retracted to a position where the developing roller 23K does not come into contact with the surface of the photoreceptor belt opposed thereto as shown in FIG. When the electrostatic latent image corresponding to the black image formed on the photoreceptor belt 1 is developed, the entire developing device 7 is moved in a horizontal direction along a guide member (not shown) by the operation of the cam 75. Then, the developing roller 23K is brought into contact with the surface of the photoreceptor belt in a state where a predetermined nip is formed therebetween.

It should be noted that the developing roller 23K is a photosensitive belt 1
When the developing roller 23K is not in contact with the developing container 23, the driving of the developing roller 23K is stopped, the developing roller 23K is controlled so as not to rotate, the toner scatters and leaks from the opening 71A of the developing container 71, the developing roller 23K, and other developing devices. 7 prevents early deterioration of the components.

Next, the color developing unit 6 used in the present color image forming apparatus will be described. FIG. 4 is a schematic configuration diagram showing the inside of the color developing unit 6 together with the black developing device 7, and FIG.
FIG. 2 is a front view showing C along with the photosensitive drum 1. As described above, the color developing unit 6 as a rotary developing device is disposed near the photoreceptor belt 1.

FIG. 4 shows a state in which the developing unit 22C for cyan is at the developing position. This color developing unit 6
Is provided with an inner casing 21 that is a rotating body rotatably provided about a rotation axis O. The inner casing 21 can be rotated in a direction indicated by an arrow D (clockwise) in FIG. ing. The inner casing 21 is provided with yellow, magenta, and cyan developing units 22.
(−Y, M, C) are integrally held. The developing units 22 (-Y, M, C) of the respective colors have the same form and are configured to perform the same operation. Each of the developing units 22Y, M, and C has a cylindrical developing roller 23Y as a developer carrier.
M and C are provided. Each developing roller 23Y, M, C
Is arranged such that a part thereof is exposed to the outside from an opening 21A formed in the inner casing 21, and is synchronized with the color information by a drive mechanism (not shown) by an arrow C in the figure.
, And develops the corresponding electrostatic latent image. At this time, the black developing device 7 is held at a position where the developing roller 23K is separated from the surface of the photosensitive belt 1 by a cam 75 and a spring (not shown).

Each of the developing devices 22Y, M, and C is a developing device using a non-magnetic one-component developer, and stores a yellow toner, a magenta toner, and a cyan toner, respectively.
Then, by rotating the inner casing 21 about the rotation axis O, each of the developing units 22Y, M, and C is selectively moved to the developing position, and is sequentially formed on the photosensitive belt 1 as described above. Develop the electrostatic latent image.

Next, the internal structure of the color developing unit 6 will be described. In addition, the developing devices 22 (-Y,
M, C) have the same form and are configured to perform the same operation.
Will be described only.

In FIG. 5, 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. Thus, the backup roller 35 is provided,
The upper portion of the one extension 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.

An opening 21A is formed above the cyan developing unit 22C. A developing roller 23C is disposed in the opening 21A so as to face the photoreceptor belt 1. The developing roller 23 </ b> C
With a predetermined peripheral speed ratio, the photosensitive drum 1 is rotated in the direction of arrow C in the drawing so that the surface moves in the same direction as the moving direction (A direction) of the belt at the portion facing the photosensitive belt 1. Also,
Below the developing roller 23C, a toner supply roller 25 as a toner supply member made of an elastic material such as foamed urethane is provided.
C is provided to rub against developing roller 23C. This toner supply roller 25C is provided with a developing roller 23C.
At a predetermined peripheral speed ratio, the roller 23C is rotationally driven so as to move in the same direction as the surface moving direction of the roller 23C in the rubbing portion with the developing roller 23C.

In the vicinity of the opening 21A, on the downstream side of the sliding portion between the developing roller 23C and the toner supply roller 25C in the direction of movement of the developing roller surface, a thin plate such as stainless steel or urethane rubber is used. Blade 26C as toner layer regulating member made of elastic material
Is provided so that the vicinity of one end thereof is in contact with the surface of the developing roller. 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. 6, a toner accommodating portion 29C is provided at one end side (the front side in FIG. 5) of the color developing unit 6 in the axial direction of the developing roller. The screw-shaped first toner conveying member 27 </ b> C
C to the developing unit 2 on the inner side of the color developing unit 6 in FIG.
Up to the side plate 2c, the developing roller 23C and the toner supply roller 25C are arranged in parallel.

The inner casing 21 is disposed so that a part thereof is in contact with the toner supply roller 25C. The first toner transport member 27C is formed by the developing roller 23C, the toner supply roller 25C and the inner casing 21. Is formed around the toner conveying space.

The screw-shaped first toner conveying member 27C is interlocked with the developing roller 23C and the toner supply roller 25C so as to convey the toner from the near side to the far side in FIGS. It is rotationally driven to rotate at a predetermined linear velocity ratio. By this rotation, the first
The toner transport member 27C transports the toner from the toner storage section 29C into the toner transport space and supplies the toner onto the toner supply roller 25C. The toner supplied onto the toner supply roller 25C is
The toner is supplied to the surface of the developing roller 23C while being charged by C, and is carried on the surface of the developing roller 23C. The toner carried on the surface of the developing roller 23C is
Accordingly, the photosensitive layer 1 is thinned to a uniform and predetermined thickness, and is used for developing an electrostatic latent image formed on the surface of the photoreceptor belt 1.
This development is performed by contact development or non-contact development.

The toner not used in the developing step is supplied to the developing device 2 on the side opposite to the front side where the toner container 29C is provided by the first toner conveying member 27C.
The toner is conveyed to the rear end of the developing roller 23C and reaches a toner circulating portion 32C provided outside the effective diameter portion in the axial direction of the developing roller 23C and the toner supply roller 25C, and the toner drops to a lower portion of the developing device 22C by gravity.

At the bottom of the developing unit 22C located at the developing position, a screw-shaped second toner conveying member 28 is provided.
C is provided in parallel with the developing roller 23C, the toner supply roller 25C, and the first toner conveying member 27C,
Is rotated so as to convey the toner in a direction opposite to that of the toner conveying member 27, and conveys the toner not used in the developing step to the toner accommodating portion 29C. These first toner conveying member 27C and second toner conveying member 28
By appropriately setting the toner transport amount of C, the developing device 22
It is possible to supply the toner onto the toner supply loaf 25C without detecting the amount of toner in C or performing complicated control of the amount of toner supply, and has a large degree of freedom in layout and a small color development with a small sectional occupation ratio to the photosensitive belt 1. Unit 6
It has become.

The toner cartridge 30C shown in the perspective view of FIG. 7 is detachably mounted on the toner container 29C. The toner cartridge 30C is mounted when the color developing unit 6 is newly mounted, and is replaced at the time of toner end, so that a necessary amount of toner is always stored in the toner storing section 29C.

Except during the image forming operation of the present color image forming apparatus, as shown in FIG. 3, in the black developing device 7, the developing roller 23K is driven by the cam 75 and a spring (not shown). It is held at a position separated from the surface of the belt 1. On the other hand, the developing device in the color developing unit 6 stops at the home position as shown in FIG. 3 at times other than the image forming operation, that is, before and after the image forming operation, I'm waiting.
In the present color image forming apparatus, the developing roller 23C of the cyan developing unit 22C and the developing roller 23 of the yellow developing unit 22Y
The rotation position of the developing device in which the intermediate position of Y is opposed to the photosensitive belt 1 and the rollers 23C and 23Y do not contact the photosensitive belt 1 is referred to as the "home position". The home position can be moved to the developing position faster and more accurately by rotating the developing device in the direction indicated by the arrow D in FIG. 3 at the start of image formation when the cyan developing device 22C used first when performing the color developing operation. Is a position that can be reached. Further, at the time of non-image forming operation, it is possible to prevent the photosensitive belt 1 and the developing roller 23 from being deteriorated or damaged due to unnecessary contact between the photosensitive belt 1 and the developing roller 23, and to adhere and fix toner outside a predetermined area. It is also a position where it can be prevented.

Next, the configuration of the main body of the present color image forming apparatus will be described with reference to FIGS. The apparatus main body structure includes a main body frame 9 as an immovable portion housing and a front frame 8 as a front housing capable of opening a transfer path of the transfer paper 17A. 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 interchangeably arranged in the center, and a fixing device 80 is arranged above the exchangeable unit. The paper discharge stack section 8
2 are formed.

The front frame 8 is supported so as to be rotatable around a rotation support shaft 9A provided on the main body frame 9 serving as a rotation fulcrum, and is usually mounted on the main body frame 9 as shown in FIG. On the other hand, it is kept closed. When a jam of the transfer paper 17A occurs in the transfer paper transport path, the front frame lock mechanism (not shown) is released, and the front frame 8 is rotated clockwise as shown in FIG. 8 to be opened. The open state of the front frame 8 can be maintained by power such as a tension spring. Since the front frame 8 holds a registration roller 20A, a transfer roller 14, and the like which are part of the transfer paper transport path, when the front frame 8 is opened, the transfer paper transport path is opened as shown in FIG. Jam processing can be performed.

When the amount of the cyan toner in the cyan developing unit 22C becomes equal to or less than a predetermined amount, the toner end is detected by a conventionally known toner end detecting means or the like, and a toner replacement display is displayed. In this case, as shown in FIG. 9, the toner cartridge 30C is replaced with the front frame 8 opened.

Next, referring to FIG. 10, the attachment / detachment replacement of the black developing device 7 of the present color image forming apparatus will be described. As described above, the black developing device 7 is configured as a so-called development cartridge (DTM). When the amount of toner in the black developing device 7 becomes equal to or less than a predetermined amount, a toner end is detected by a conventionally known toner amount detecting unit (for example, an optical sensor, a magnetic sensor, or a piezoelectric element) which is not shown. The exchange sign is displayed on a display panel, for example.

A sub-frame 9B is attached to the rotation shaft 9A of the front frame 8 so as to be rotatable about the rotation shaft 9A. The process cartridge 31 is detachably held on the sub-frame 9B.
When replacing the black developing device 7, the sub-frame 9B is rotated together with the front frame 8 about the rotation shaft 9A, and the process cartridge 31 is combined with the front frame 8 as shown in FIG. To evacuate. As a result, a device opening for attaching and detaching the black developing device 7 appears, and the black developing device 7 can be easily replaced without temporarily removing the process cartridge 31 outside the image forming apparatus main body.

Next, with reference to FIG. 11, the attachment / detachment replacement of the color developing unit 6 of the present color image forming apparatus will be described. In normal full-color image formation, although the consumption of toner differs depending on the color, the amount of use of each developing device using yellow toner, magenta toner and cyan toner is almost the same. The above-described black developing device 7
Is replaced by, for example, thousands of sheets due to the capacity limitation of the developing container 71. However, the color developing unit 6 is required to reduce the frequency of replacement work, improve operability and substantially use the unit for a long time. For reasons such as cost reduction, for example, when the tens of thousands of sheets are counted, the three developing units of yellow, magenta, and cyan are replaced together. When the count of the used amount (image formation number) of the color developing unit 6 stored in the internal memory or the like of the color image forming apparatus main body reaches a predetermined value, the life sign of the unit is displayed on a display panel, for example. . Thereafter, when the toner end of the black developing device 7 is detected, a sign of simultaneous replacement of the black developing device 7 and the color developing unit 6 is displayed on a display panel, for example. With this sign, the operator rotates the sub-frame 9B together with the front frame 8 about the rotation shaft 9A as in the case of replacing the black developing device 7, and as shown in FIG. The cartridge 31 is retracted while being combined with the front frame 8.

Next, the cover member and the handle member of the color developing unit 6 will be described. In FIG.
At both ends in the longitudinal direction of the color developing unit 6, disk (cylindrical) side plates 55, 57 which are in close contact with both ends of the above-mentioned inner casing 21 and constitute the developing devices of each color are provided. Disk (cylindrical) sliding portions 55A, 57A having the same diameter are provided on both side plates 55, 57, respectively.
The stopper portions 55B, 57B having an outer diameter larger than the outer diameter of the sliding portions 55A, 57A are provided outside the respective 57A.
Is provided.

A cover member 41 is provided between the stoppers 55B and 57B. The inner peripheral surface of the cover member 41 has the sliding portions 55A,
7A is slidably disposed so as to be in contact with the outer peripheral surface of 7A. That is, the inner diameter of the cover member 41 is
5A, 57A, the stoppers 55B,
It is set smaller than the outer diameter of 57B. Thus, the cover member 41 is slidably rotatable with respect to the developing device unit main body, and positioning in the thrust direction is performed by the two stopper portions 55B and 57B. (Hereinafter, margin)

FIG. 12 is a partial sectional view showing the internal structure of the color developing unit 6. The side plate 55 provided on the right side (drive side) in the figure has a multi-stage cylindrical outer diameter, and has a bowl-shaped recess formed therein. The coupling gear 5 provided in each of the developing units 22-Y, M, and C described above.
1, a gear 50 attached to the shaft of the developing roller 23, and a gear 5 attached to the shaft of the toner conveying member 28
4 and the like are stored in the bowl-shaped recess of the side plate 55. A disk-shaped drive unit cover 56 having holes at positions corresponding to the coupling gears 51 and the rotation center axis O is attached to a side portion of the side plate 55. As a result, the driving section in the color developing unit 6 is not exposed to the outside of the apparatus, and foreign matter is mixed into the driving system, and the driving system is damaged or abnormal, and the safety of the operator is secured. ing.

By appropriately setting the outer diameter of the drive unit cover 56, the diameter of the hole through which the rotation center axis O passes, and the positional accuracy, the side plate 55 having the bowl-shaped recess is provided.
And the deflection and positional accuracy with respect to the rotation center axis O are secured.

The drive unit cover 5 for the rotation center axis O
A positioning roller 58 is mounted coaxially with the shaft O and rotatably with respect to the shaft O at a portion located outside the shaft 6. When the color developing unit 6 is mounted on the color image forming apparatus main body, the positioning roller 58 is engaged with the receiving portion 59A provided on the side plate 591 on the color image forming apparatus main body side. Unit 6
Is positioned on the drive side.

The side plate 57 provided on the left side (toner container side) in FIG. 12 has a multistage cylindrical outer diameter similarly to the side plate 55 on the driving unit side, and has a bowl-shaped recess inside. Is formed. The axial ends of the developing roller 23 and the toner supply roller 25 have their positions in the thrust direction regulated by, for example, an E-shaped retaining ring in the recess in the side plate 57. Further, an electrode plate 60 made of a plate material having a spring property such as phosphor bronze is arranged at both ends of the shafts in contact with the respective color developing devices. A part of the electrode plate 60 extends from the inside of the cylindrical portion of the side plate to the outer peripheral portion, and forms a contact portion 60A extending along the outer peripheral surface of the cylindrical portion.

On the other hand, on the color image forming apparatus main body side, a bias supply electrode 63 also having a spring property and connected to a high-voltage power supply not shown is provided. When the developing device in the color developing unit 6 rotates and a certain developing device is located at the developing position and in the vicinity thereof, the contact portion 6
0A is in sliding contact with the bias supply electrode 63, and a predetermined bias is supplied to the developing device.

The configuration in which a common bias is applied to the developing roller 23 and the toner supply roller 25 has been described above.
For example, by disposing the contact portion 60A of the electrode plate 60 and the bias supply electrode 63 in parallel, it is possible to simultaneously supply different biases.

A shaft 62 is fixed to the side plate of the main body of the color image forming apparatus on the side of the toner container 29, and a pair of support rollers 61 are rotatably provided around the shaft 62. When the color developing unit 6 is mounted on the color image forming apparatus main body, the cylindrical outer peripheral portion 57A of the side plate 57 on the developing unit 6 side is supported on the outer peripheral portion of the pair of support rollers 61,
As a result, the color developing unit 6 is rotatably positioned.

Since the outer peripheral portion 57A of the side plate 57 of the color developing unit 6 is covered with the cover member 41, when the color developing unit 6 is mounted on the main body of the color image forming apparatus, the support rollers 61 are provided. A hole 42 is provided at a position of the cover member 41 corresponding to FIG. By covering the cylindrical outer peripheral portion 57A of the side plate 57 supported by the outer peripheral portion of the support roller 61 with the cover member 41, the cylindrical outer peripheral portion 57a which requires component precision for positioning the developing device is protected. Have been. Therefore, the toner and other foreign matters are not covered with the cylindrical outer peripheral portion 57A.
Can be prevented from invading and adhering to
The position of the developing device is always accurately supported.

Further, a seat portion 44 is formed integrally with the cover member 41 at a lower portion near both ends in the longitudinal direction of the cover member 41. The seat portion 44 has a flat bottom surface so that the color developing unit 6 can be stably mounted when the color developing unit 6 is taken out of the color image forming apparatus main body. In addition, the seat 44
When the color developing unit 6 is mounted on the color image forming apparatus main body as shown in FIG. 13, the color developing unit 6 is mounted so as to have a slight gap with the stopper portion 59B of the color image forming apparatus main body. Thereby, the color developing unit 6
When each of the developing units 22 performs the above-described rotation operation,
The cover member 41 is formed by the seat portion 44 and the stopper portion 59B.
Indicates that each of the developing units 22 inside the
Only the member rotates while sliding with respect to the cover member 41.

Next, the cover member 41 of the color developing unit 6 will be further described with reference to FIGS. FIGS. 14A and 14B are perspective views of the cover member 41 in an opened state and a closed state, respectively. FIG. 15A is a front view of the cover member 41 in an opened state and a closed state, and FIGS. 15B and 15C are enlarged views of a hinge portion and a locking portion of the cover member 41. It is.

As described above, the cover member 41 has the substantially cylindrical member integrally formed with the seat portion 44. When the color developing unit 6 is mounted on the color image forming apparatus main body, the cover member 41 and the photosensitive belt 1 are separated from each other. An opening 45 is provided at an opposing position. Further, a part of the circumferential portion of the cover member 41 has a thin hinge portion 46 over the entire region in the longitudinal direction, and a releasable separation engagement portion 47 provided at a position substantially opposite to the hinge portion 46. , And is divided into two in the circumferential direction. The divided upper cover portion 41A and lower cover portion 41B of the cover member 41 are integrally formed, and are connected by a hinge portion 46. This cover member 41 is
It can be opened and closed around a thin hinge portion 46. Locking portions 48 and 49 for engaging and fixing the upper cover portion 41A and the lower cover portion 41B are formed in the separation engaging portion 47 of the cover member 41, respectively, and cover the assembled developing device 22. Cover member 41 is attached as described above.

Next, with reference to FIGS. 14 and 16, a description will be given of a handle member used when the color developing unit 6 is attached, detached, or replaced. At an upper portion near both ends in the longitudinal direction of the cover member 41, a handle member 43 is attached to the outer peripheral portion of the cover member 41 so as to be closely housed. Using the handle member 43, the color developing unit 6 is attached to and detached from the color image forming apparatus main body. When the color developing unit 6 is taken out of the image forming apparatus and left to stand, or when the color developing unit 6 is attached or detached using the above-mentioned handle member, the load of the color developing unit unit composed of the developing device, etc. Acting on the lower cover of the member 41, the inner peripheral surface of the cover member 41 and the aforementioned side plates 55, 57
The frictional force between the outer peripheral surfaces of the sliding portions 55A and 57A prevents the color developing unit main body from being inadvertently rotated with respect to the cover member 41.

Conversely, when the color developing unit 6 is mounted on the color image forming apparatus main body, the cover member 41 is provided between the outer peripheral portions of the sliding portions 55A, 57A of the side plates 55, 57. Since only the load of 41 acts on the main body of the color developing unit, the frictional force between them is extremely small, and the developing unit 22 and the like on the main body of the developing unit can slide and rotate easily with respect to the cover member 41.

The lower cover 41B, to which the load of the main body of the developing unit is applied when the color developing unit is attached / detached, is integrally provided with projections 411 and 412 used for mounting the handle 43. Is provided. As shown in FIG. 17C, the projections 411 and 412 have a mushroom-like outer diameter. On the other hand, the handle member 43 is a sheet-like member made of a flexible material such as polypropylene and polyethylene. As the shape of the pair of handle members 43, from the viewpoint of reducing the number of types of parts, it is necessary to distinguish between the same shape as shown in FIG. 17A and the front and back surfaces as shown in FIG. It is preferable to adopt a symmetrical shape that can be used without any problem. The handle member 43 includes the protrusions 411 and 41.
A hole 43A and a long hole 43B that engage with the second constriction are formed. With the hole 43A inserted into the projection 411 of the cover member 41 and the elongated hole 43B inserted into the projection 412, the handle member 43 is pulled up.
The handle member 43 slides along the protrusion 412 to form a space 413 between the handle member 43 and the cover member 41 as shown in FIG. 19A. The attachment / detachment and replacement of the developing unit 6 can be performed.

Further, since the handle member 43 is attached to the lower cover portion 41B of the cover member, the load of the developing device unit main body that is applied when the color developing device unit 6 is actually attached or detached or replaced is held by the lower cover portion 41. it can. Therefore, the hinge portion 46, which is the connecting portion of the cover member 41,
The separating and engaging portion 47 only needs to have a strength enough to prevent the cover member 41 from being opened, and the attachment and detachment and replacement of the color developing unit 6 can be performed safely and reliably.

As shown in FIGS. 17 (b) and 18,
When the operation portion of the handle member 43 held by the operator is shifted inward from both ends in the longitudinal direction of the cover member 41, the operation portion is close to the developer unit side of the toner cartridge 30 or the main body of the color image forming apparatus during the operation. With the member
It is possible to secure a sufficient distance between the handle unit 43 and the operation unit,
The operator can easily hold the handle member 43 and can also prevent the injury of the operator. Further, it is also possible to attach the handle members 43 to positions where both ends of the cover member 41 are full. In this case, the cover member 41 can be provided without increasing the length of the color developing unit unit main body in the longitudinal direction. Opening 45 can be sufficiently secured. Note that the configuration of the cover member 41 is not limited to the one having an integral structure, and may be configured by combining, for example, members that can be separated into upper and lower parts.

FIGS. 19 (a) and 19 (b) are views for explaining the storage of the handle member 43 when not in use. FIG.
As shown in (a), when the color developing unit 6 is mounted on the main body of the color image forming apparatus and the handle member 43 is extended upward during use, the mounting of the color developing unit 6 is performed. Later, it interferes with other units or parts that are further mounted or moved and fixed to the color image forming apparatus main body, and these units are positioned at predetermined positions and are not fixed. ,
Or it may cause damage to the parts.

For this reason, this color image forming apparatus is
As shown in FIG. 9B, the direction in which the handle member 43 is stored is set to the direction of arrow S in the figure. After the color developing device unit 6 is mounted, when the black developing device 7 is mounted in the direction of arrow T in the figure, the handle member 4 is pressed by the bottom surface of the black developing device 7.
Even when 3 is in use, it automatically moves in the direction of arrow S and is stored in close contact with the outer peripheral portion of the cover member 41. In addition, as shown in FIG. 19, the color image forming apparatus in which the handle member 43 is stored by the mounting operation of the black developing device 7 is shown. For example, the process cartridge 31 described above and the setting of the main body frame 8 of the color image forming apparatus are set. You may comprise so that it may perform in connection with operation | movement. Further, the color image forming apparatus employing the intermediate transfer method using the intermediate transfer belt 10 has been described, but a configuration may be adopted in which images of a plurality of colors are superimposed on the photosensitive belt 1.

The conventional color image forming apparatus having the cover member 41 (hereinafter referred to as a conventional color image forming apparatus) has been described in detail. According to this conventional color image forming apparatus, since the cover member 41 is provided on the peripheral surface of the color developing unit 6, the inside of the apparatus main body is contaminated by toner scattering from each developing unit, or the black developing device 7 The problem that the black toner scatters and causes the contamination inside the apparatus main body and the color mixture of the black toner to the respective developing devices and the like can be solved.

However, in the above-mentioned conventional color image forming apparatus, if the strength of the cover member 41 is insufficient, for example, when the black developing device 7 is attached or detached, an external force is applied to the cover member 41 by contact. In the case, the cover member 4
Due to the deformation 1, the developing roller of each developing unit of the color developing unit 6 may be damaged. When a resin molded product is used for the cylindrical cover member 41, for example, warping or distortion is likely to occur during molding and processing.
The warping and distortion may damage the developing roller and the like of each developing device, and may scatter the toner on the developing roller.

Therefore, the color image forming apparatus of this embodiment has the following characteristic configuration in addition to the configuration of the above-described conventional color image forming apparatus. Hereinafter, a characteristic configuration of the color image forming apparatus of the present embodiment will be described.

FIG. 20 is a perspective view of the cover member 41 in the color image forming apparatus of this embodiment. As shown in the drawing, in the present embodiment, an upper portion of the cover member 41, that is, a portion of the cover member 41 facing the black developing device 7,
Rib shapes 401 and 402 extending in the axial direction of the rotation axis O
Is provided. By providing the cover members 41 with the rib shapes 401 and 402 in this manner, the strength of the cover member 41 in the axial direction can be increased, and deformation of the cover member 41 such as warpage or distortion can be reduced.

Further, in this embodiment, the second rib shape is provided so that the upper portion is horizontal, that is, parallel to the attaching / detaching direction of the black developing device 7, and is installed so as to be orthogonal to the rib shapes 401 and 402. 403 are provided. In this manner, by bridging the second rib shape 403 so as to be orthogonal to the rib shapes 401 and 402, the strength of the cover member 41 can be further increased, and the deformation of the cover member 41 can be further reduced. In addition, by providing the upper portion of the second rib shape 403 in parallel with the attaching / detaching direction of the black developing device 7, the upper portion of the cover member 41 can be used as an operation guide for attaching / detaching the black developing device 7. In addition, the second
By making the upper part of the rib shape 403 function as an operation guide for attachment / detachment of the black developing device 7, it is not necessary to newly provide a member for the operation guide for attachment / detachment.

As described above, according to the color image forming apparatus of the present embodiment, the rib shapes 401 and 402 reduce the deformation of the cover member 41, so that the deformation of the developing rollers in the color developing unit 6 and the toner Scattering can be reduced. Further, since the plurality of second rib shapes 403 further reduce the deformation of the cover member 41, it is possible to further reduce damage to each developing roller in the color developing unit 6 and toner scattering due to the deformation. Also, the cover member 41
Can be used as a guide for attaching / detaching the black developing device 7, so that the operability of attaching / detaching the black developing device 7 can be improved. Further, since it is not necessary to newly install a member for causing the upper portion of the cover member 41 to function as a guide for the attachment / detachment operation of the black developing device 7, an increase in initial cost due to the installation can be avoided.

Next, an embodiment in which the configuration of the cover member 41 is made more specific will be described. FIG. 21A is a perspective view of the cover member 41 in the color image forming apparatus of the present embodiment, and FIG. 21B is a cross-sectional view of the cover member 41.
As shown in the figure, the cover member 41 of the present embodiment has a planar shape 404 having a plane parallel to the attaching / detaching direction of the black developing device 7 above the second rib shape 403. Then, the operator can use the planar shape 404 to cover the cover member 4.
1 can be easily recognized as an operation guide for attaching and detaching the black developing device 7. In addition, an arrow or operation procedure in the attaching / detaching direction can be displayed on the planar shape 404 by integrally forming or attaching a decal (seal) or the like.

As described above, according to the color image forming apparatus of this embodiment, the operator can easily recognize the upper portion of the cover member 41 as an operation guide for attaching and detaching the black developing device 7, so that the upper portion can be recognized by the operator. It can be reliably used as the attaching / detaching operation guide.

FIG. 22A is a perspective view of a cover member 41 in a modification of the above embodiment, and FIG.
(B) is a sectional view of the cover member 41. As shown in the figure, the cover member 41 of this modified example device has a plurality of second members.
A member for bridging the side portion of the rib shape 403 is further provided, and the strength of the cover member 41 is further increased. (Hereinafter, margin)

Further, the cover member 41 and the rib shape 401,
Although the image forming apparatus in which 402 and 403 are integrally formed has been described, the cover member 41 and the rib shape 401,
402 and 403 are also formed separately.
The present invention is applicable.

Further, as shown in FIGS. 23A and 23B, the second rib member 4
03 may be installed at an angle.

[0092]

According to the first or second aspect of the present invention, since the deformation of the cover member is reduced, it is possible to reduce damage to each developing roller and toner scattering of the rotary developing device due to the deformation. Has an excellent effect.

According to the third aspect of the present invention, since the deformation of the cover member is further reduced, it is possible to further reduce damage to the developing rollers of the rotary developing device and toner scattering due to the deformation. effective.

According to the fourth aspect of the present invention, since the upper portion of the cover member can be used as a guide for attaching and detaching the first developing device, the operability of attaching and detaching the first developing device is improved. effective.

According to the fifth aspect of the present invention, there is no need to newly provide a member for causing the upper portion of the cover member to function as a guide for attaching and detaching the first developing device.
There is an excellent effect that an increase in initial cost due to the installation can be avoided.

According to the sixth aspect of the present invention, the operator can easily recognize the upper portion of the cover member as the operation guide for attaching and detaching the first developing device. There is an excellent effect that it can be reliably used as a guide.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of a conventional color image forming apparatus including a cover member 41.

FIG. 2 is a sectional view showing an internal structure of a color developing unit 6 and a black developing device 7 of the color image forming apparatus.

FIG. 3 is a sectional view showing the internal structure of the color developing unit 6 and the black developing device 7 during non-image formation.

FIG. 4 is a sectional view showing the internal structure of the color developing unit 6 and the black developing device 7 during color development.

FIG. 5 is a sectional view showing an internal structure of a cyan developing unit of the color developing unit 6;

FIG. 6 is a cross-sectional view of the cyan developing device as viewed from the side.

FIG. 7 is a perspective view of the color developing unit 6;

FIG. 8 is a cross-sectional view of the color image forming apparatus in an open state of a front frame.

FIG. 9 is an explanatory diagram of an attaching / detaching operation of a toner cartridge in the color image forming apparatus.

FIG. 10 shows a black developing device 7 in the color image forming apparatus.
FIG.

FIG. 11 is an explanatory diagram of an attaching / detaching operation of the color developing unit in the color image forming apparatus.

FIG. 12 is a partial cross-sectional view of the color developing unit 6 viewed from a side.

FIG. 13 is a partial cross-sectional view of one developing unit in the color developing unit 6 viewed from a side.

14A and 14B are perspective views of the same cover member 41, respectively.

FIG. 15A is an explanatory diagram illustrating an open state and a closed state of the cover member 41. (B) is an enlarged view of the hinge part of the same cover member 41. (C) is an enlarged view of a separation engagement portion of the cover member 41.

FIG. 16 is a side view of the color developing unit 6;

17 (a) and (b) are exploded plan views of a handle member 43 attached to the cover member 41. FIG. (C) is an enlarged view of a protrusion formed on the cover member 41.

FIG. 18 is a side view of a color developing unit 6 to which a handle member 43 according to a modification is attached.

FIGS. 19A and 19B are explanatory diagrams of automatic storage of the handle member 43 in the color developing unit 6. FIG.

FIG. 20 is a perspective view of a cover member 41 of the color developing unit 6 in the image forming apparatus according to the embodiment.

FIG. 21A is a perspective view of a cover member 41 in the image forming apparatus according to the present embodiment. (B) is the cover member 41
FIG.

FIG. 22A is a perspective view of a cover member 41 according to a modified example of the embodiment. (B) is sectional drawing of the same cover member.

FIG. 23A is a perspective view of a cover member 41 according to a modified example of the embodiment. (B) is sectional drawing of the same cover member.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoreceptor belt 2, 3 rotating roller 4 charging charger 5 light writing unit 6 rotating color developing unit 7 black developing device 8 front frame 9 main body frame 10 intermediate transfer belt 21 inner casing 22 developing device 23 developing roller 31 process cartridge 41 cover member 41A upper cover portion 41B lower cover portion 42 hole portion 43 handle member 43A hole 43B long hole 44 seat portion 45 opening 46 hinge portion 47 separation engaging portion 48, 49 locking portion 401 rib shape 402 rib shape 403 second Rib shape 404 Plan shape

Claims (6)

[Claims] A rotary image developing device having a latent image carrier for forming a latent image on a surface thereof, a plurality of developing devices disposed around a rotary shaft, and an opening at a developing position opposed to the surface; And a cover member that covers the plurality of developing devices, and the developing device is moved to the developing position by rotating the rotary developing device about the rotary shaft to move the latent image to the developing position. An image forming apparatus for developing an image, wherein a rib shape extending in the axial direction of the rotation shaft is formed on the cover member. 2. The image forming apparatus according to claim 1, wherein said latent image carrier is opposed to said latent image carrier at a developing position different from said developing position.
A second developing device for developing the color separation latent image corresponding to black with a black developer is detachably disposed above the rotary developing device, and each developing device of the rotary developing device includes: An image forming apparatus, wherein the color separation latent images respectively corresponding to predetermined colors other than black are sequentially developed with the developer of the predetermined color. 3. The image forming apparatus according to claim 1, wherein
An image forming apparatus, wherein the second rib shape is formed to extend in a direction different from the axial direction with respect to the rib shape. 4. The image forming apparatus according to claim 3, wherein said second developing device which moves in a mounting / removing direction is supported on an upper portion of said cover member. 5. The image forming apparatus according to claim 4, wherein said second rib shape is formed in a direction parallel to said attaching / detaching direction, and said second developing device moving in said attaching / detaching direction is supported by said second rib shape. An image forming apparatus comprising: 6. An image forming apparatus according to claim 4, wherein a planar shape is formed on an upper portion of said cover member, and said second developing device moving in said attaching / detaching direction is supported by said planar shape. Forming equipment.