JP2000122433A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a color image forming device provided with an intermediate transfer body. SOLUTION: Relating to this color image forming device, a latent image carrier 1 and the intermediate transfer body 5 are constituted in a belt shape, and a primary transfer part 29 for collectively transferring the colors overlapped toner image from the latent image carrier 1 to the intermediate transfer body 5 is formed in a region being a part of the intermediate transfer body 5 and being extended between two rolls of the primary transfer rollers 30 and 31 with prescribed tension, by allowing one roll of primary transfer counter roller 4 to be pressed following the rotation of the latent image carrier 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus such as a copying machine, a facsimile, and a printer capable of forming a color image such as a color copying machine and a color printer.

[0002]

2. Description of the Related Art A developing device for developing an electrostatic latent image formed on a latent image carrier with a plurality of color developers containing at least toner is provided, and a toner image formed on the latent image carrier is developed. A color image forming apparatus having a function of transferring a toner image on the intermediate transfer body onto a transfer material after transferring the toner image onto the intermediate transfer body and further fixing the toner image on the transfer material by a fixing unit is disclosed in JP-A-92759, JP-A-7-225505, JP-A-8-146794, and the like.

In the above-mentioned technique, a plurality of image forming unit groups having toners of different colors are rotatably moved so that they can be sequentially moved to the same image forming position. And transfers the color toner image to the opposed intermediate transfer belt. For each image forming unit, a color-superimposed toner image is formed at the same position on the intermediate transfer belt, and the color-superimposed toner image is collectively transferred and fixed on a sheet to obtain a color image.

In the above-mentioned technique, a rotary type developing device having respective color developing devices having toners of different colors is arranged opposite to a photosensitive drum, and a latent image formed in a corresponding color on the photosensitive drum is converted to a corresponding color. A toner image is formed by visualizing with a developing device, and the toner image is transferred to a transfer drum, and the same operation is performed for other colors to form a color-overlaid toner image on the transfer drum. The color superimposed toner image is collectively transferred to a transfer material and fixed to obtain a color image.

[0005] In the above technique, each color developing device having a different color toner is arranged around a photosensitive drum, and
An intermediate transfer drum (or an intermediate transfer belt) is arranged facing the photosensitive drum, and a latent image formed in a corresponding color on the photosensitive drum is visualized by a developing device of a corresponding color to form a toner image. This toner image is transferred to an intermediate transfer drum (or an intermediate transfer belt), and the same operation is performed for other colors to form a toner image of a color overlap on the intermediate transfer drum (or the intermediate transfer belt). The color superimposed toner image is collectively transferred to a transfer material and fixed to obtain a color image.

[0006]

The above technique employs a system in which a plurality of image forming unit groups each having a toner constitute one rotating body and the rotating body rotates intermittently. Further, in the above technique, each color developing device constitutes one rotating body, and a method is adopted in which the rotating body rotates intermittently. These rotating bodies occupy a large space. Therefore, it is difficult to reduce the size of the apparatus by any of the above techniques.

Accordingly, it is an object of the present invention to provide a color image forming apparatus capable of reducing the size of the apparatus.

[0008]

The present invention has the following configuration to achieve the above object. (1). A developing device for visualizing the electrostatic latent image formed on the latent image carrier with a developer of a plurality of colors including at least toner, and transferring the toner image formed on the latent image carrier onto an intermediate transfer body. A color image forming apparatus having a function of transferring the toner image on the intermediate transfer member onto a transfer material after transferring, and further fixing the toner image on the transfer material by a fixing unit; Both the intermediate transfer member is formed of an endless belt, and the latent image carrier and the intermediate transfer member are respectively provided on an independent latent image carrier unit and an intermediate transfer member unit which can be detached from the apparatus main body independently, A plurality of primary transfer rollers capable of rotating a primary transfer unit for transferring a toner image formed on the latent image carrier onto the intermediate transfer body following the rotation of the intermediate transfer body; Can rotate following the rotation of the carrier And the primary transfer facing roller, wherein the primary transfer facing roller is stretched with a predetermined tension between a plurality of primary transfer rollers. The transfer region is formed by pressing the transfer region (claim 1).

(2). (1) In the color image forming apparatus described in (1), the intermediate transfer belt is disposed between the plurality of primary transfer rollers in a direction perpendicular to an axial longitudinal direction of a roller that supports the latent image carrier and between the plurality of primary transfer rollers. The latent image carrier unit is movably guided in an arbitrary attachment / detachment direction different from the normal direction so that the latent image carrier unit can be detached from the apparatus main body.

(3). (2) In the color image forming apparatus described in (2), the longitudinal directions of the belt-shaped portions of the latent image carrier and the intermediate transfer member are respectively arranged in a substantially vertical direction, and the attaching / detaching direction is defined as a vertical direction. (Claim 3).

(4). In the color image forming apparatus according to (1), (2) or (3), the primary transfer facing roller provided in the latent image carrier unit may be configured to be the first transfer opposing roller.
Support means for reciprocatingly supporting the shaft of the primary transfer opposing roller so as to be able to take a projecting position that can interfere with the next transfer roller and a retracted position that cannot interfere with the next transfer roller; A tension roller that applies tension, and is provided in the intermediate transfer unit, and engages with the shaft portion in accordance with the attaching / detaching operation of the latent image carrying unit in a process of attaching / detaching the latent image carrying unit to / from the apparatus main body. A guide member for moving the shaft portion between the retracted position and the projecting position is provided (claim 4).

(5). (4) In the color image forming apparatus described in (4), a pressing member for pressing the shaft portion against the supporting means or the guide member is provided.

(6). (5) In the color image forming apparatus described in (5), the pressing member is formed of a contractible spring provided between the shaft portion and the latent image carrier unit.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [1] Example Corresponding to Claim 1 In FIG. 1 illustrating an example of a color image forming apparatus, reference numeral 1 denotes a latent image carrier, which is formed by an endless belt. The latent image carrier is stretched between two support rollers 2 and 3 which are vertically opposed and a primary transfer opposed roller 4 provided at an intermediate position between the support rollers 2 and 3. As a result, the latent image carrier 1 has a vertical belt portion between the support rollers 2 and 3 and a belt bent in a “<” shape by being supported by the primary transfer opposing roller 4 between the support rollers 2 and 3. And a part.

Reference numeral 5 denotes an intermediate transfer member 5, which comprises an endless belt. The intermediate transfer member 5 includes two support rollers 6 and 7 which are vertically opposed to each other, and a secondary transfer opposed roller 8 provided at an intermediate position between the support rollers 6 and 7.
It is stretched between. As a result, the intermediate transfer body 5 has a vertical belt portion between the support rollers 6 and 7 and the support rollers 6 and 7.
And a belt portion bent in a “<” shape by being supported by the secondary transfer opposing roller 8 between the belts 7.

The primary transfer opposing roller 4 faces the belt portion of the belt portion of the intermediate transfer member 5 that is supported along the vertical direction between the support rollers 6 and 7 and interposes the latent image carrier 1 in the middle. The transfer member 5 is supported so as to be in contact therewith. As described above, the component (1) in which the process in which the latent image carrier 1 is brought into contact with the intermediate transfer body 5 and the toner image formed on the latent image carrier 1 is transferred to the intermediate transfer body 5 is executed.
The area between the next transfer rollers 30 and 31 where the intermediate transfer body 5 and the latent image carrier 1 are in contact with each other by the primary transfer opposing roller 4) is referred to as a primary transfer section 29.

Further, in the latent image carrier 1, an opposing roller 10 is provided at a position between the support roller 3 and the primary transfer opposing roller 8 so as to oppose the cleaning blade 9a. Further, as for the intermediate transfer member 5, the support roller 6
A tension roller 11 is provided at a position between the roller and the secondary transfer opposing roller 8.

The support roller 3 and the support roller 7 are drive rollers each driven by a drive system (not shown).
In FIG. 1, the latent image carrier 1 is driven by these drive rollers.
Is driven to rotate in the counterclockwise direction indicated by the arrow, and the intermediate transfer member 5 is driven to rotate in the clockwise direction indicated by the arrow at the same linear speed as the latent image carrier 1.

In the belt portion of the latent image carrier 1, the yellow developing device 12 is arranged from the upstream side in the rotation direction indicated by an arrow in opposition to the belt portion stretched along the vertical direction.
Y, magenta developing device 12M, cyan developing device 12
C and black developing devices 12BK are arranged. Each of these developing devices includes developing rollers 14Y, 14M, 14C, and 14BK at a portion facing the intermediate transfer member 1.

Each of these developing devices is guided by guide means (not shown) so as to be able to advance toward the latent image carrier 1 and to retreat away from it. The rear ends are cams 13Y, 1
3M, 13C, and 13BK are urged by urging means (not shown) so as to come into contact with them. In this state, the developing rollers 14Y, 14M, 14C, and 14BK cannot be developed because they are separated from the latent image carrier 1.

At an appropriate timing, these cams 13Y,
By rotating any of 13M, 13C, and 13BK, the developing device corresponding to the rotated cam moves forward, and the developing roller of the developing device approaches the intermediate transfer member 1 to be in a state capable of developing.

At the lower right of the lower support roller 3, a writing device 15 is provided. The writing device 15 irradiates the exposure light Lb toward a portion of the latent image carrier 1 supported by the support roller 3.

Exposure light Lb emitted from the rotary polygon mirror 15a provided in the writing device 15 is transmitted to the imaging optical system 15b,
The latent image carrier 1 is irradiated via the mirror 15c. The writing device 15 can appropriately emit four types of exposure light Lb corresponding to each color of yellow, magenta, cyan, and black in accordance with the timing of exposure.

Assuming that the irradiation position of the exposure light Lb by the writing device 15 on the latent image carrier 1 is referred to as an exposure section, a portion upstream of the exposure section in the rotational direction of the latent image carrier 1 is charged. A cleaning device 9 having a cleaning blade 9a is provided at a position further upstream than the charger 16.

On the other hand, around the intermediate transfer member 5, a cleaning device 9 is provided above the upper support roller 6, and a cleaning brush 17a is brought into contact with the intermediate transfer member 5 supported by the support roller 6. Is provided. Further, an opposing roller 18 is provided in opposing contact with the secondary transfer opposing roller 8. A contact portion between the opposing roller 8 and the secondary transfer opposing roller 8 via the intermediate transfer member 5 is a secondary transfer portion 19. At each position, a transfer path of the transfer material as shown by a broken line is formed along the opposing guide plate.

This transport path is a path leading from the tray 20 containing the paper S as a transfer material to the paper discharge tray 26. On this path, from the upstream to the downstream, the paper feed roller 21 → a pair Conveying roller 22 → a pair of registration rollers 2
3 → secondary transfer section 19 → fixing device 24 → a pair of paper discharge rollers 2
5 etc. are located. The paper S can also be sent out from the paper feed roller 28 with the manual paper feed table 27 as a guide, so that the transport paths merge at a position upstream of the registration roller 23 as shown by a broken line. It has become.

In such a color image forming apparatus,
Image formation is performed as follows. While the latent image carrier 1 is rotating, the latent image carrier 1 charged to a predetermined potential required for forming a latent image by the charger 16 in the dark in the dark has a predetermined color predetermined by the writing device 8. For example, a latent image pattern for yellow is formed. By driving a developing device of a predetermined color corresponding to the color of the latent image, that is, a cam 13Y attached to the developing device 12Y, the developing device 1
By moving the developing roller 14Y close to the latent image carrier 1 by moving 2Y, yellow toner is adhered to the latent image carrier 1 and developed to obtain a yellow visible image.

The toner image on the latent image carrier 1 thus visualized rotates together with the latent image carrier 1 to reach the primary transfer section 29, and is transferred by the transfer electric field provided by the primary transfer opposing roller 4 to the intermediate transfer body. 5 is transferred. The same operation is sequentially performed for the other three colors of magenta, cyan, and black, and a four-color superimposed full-color toner image is finally formed on the intermediate transfer member 5.

On the other hand, the transfer paper S is fed out of the tray 20 by the paper feed roller 21 at an appropriate timing, temporarily stops at the position of the registration roller 23 via the transport roller 22, and the full-color toner image on the intermediate transfer body 5 The transfer sheet 19 waits for a sending timing so as to match, and when this timing comes, the transfer paper S stopped at the position of the registration roller 23 is sent from the registration roller 23,
The image is transferred onto the transfer sheet S in the secondary transfer section 19.

The transfer sheet S onto which the full-color toner image has been transferred in this manner is fixed while passing through the fixing device 24, and is discharged to a discharge tray 26 via a discharge roller 25. On the other hand, the residual toner remaining on the intermediate transfer member 5 is cleaned by the cleaning device 17.

As described above, the latent image carrier 1 and the intermediate transfer member 5
Are constituted by endless belts, and the belts are stretched in such a manner that the lengthwise direction of the belts is substantially parallel between the latent image carrier 1 and the intermediate transfer body 5. In this state, two belts having a substantially flat shape are superimposed in the same direction (horizontal direction in this example), so that the latent image carrier, the intermediate transfer body, and the like are formed in a cylindrical shape. A large space is not required as compared with the image forming apparatus, so that the color image forming apparatus can be downsized.

As described above, the latent image carrier 1 and the intermediate transfer member 5 are both constituted by endless belts, and the transfer area for transferring the toner image of the latent image carrier 1 to the intermediate transfer member 5 is the intermediate transfer member. If the intermediate position is between the two support rollers 6 and 7 in the body 5, there is a possibility that a stable and appropriate transfer area cannot be maintained due to looseness of the belt.

In order to solve this problem, in the present embodiment, the configuration around the latent image carrier 1 and the intermediate transfer member 5 in the color image forming apparatus shown in FIG. 1 is as shown in FIG.

In FIG. 2, a primary transfer section 29 for transferring the toner image formed on the latent image carrier 1 onto the intermediate transfer body 5
Is formed by two primary transfer rollers 30 and 31 rotatable following the intermediate transfer member 5 and a primary transfer opposing roller 4 rotatable following the rotation of the latent image carrier 5. So that the primary transfer opposing roller 4 is
It is configured to press against the intermediate transfer belt 5 stretched between 0 and 31 with a predetermined tension.

The intermediate position of the intermediate transfer belt 5 stretched between the two primary transfer rollers with a predetermined tension is set to 1
By pressing with the primary transfer roller 4, a transfer area of about several mm can be reliably and stably secured. In the present embodiment, the mode is such that the primary transfer opposing roller 4 is harder to be located inside the common tangent line of the primary transfer rollers 30 and 31.

More specifically, the latent image carrier 1
Are formed in a latent image carrier unit 32 which is independently detachable from the color image forming apparatus. The frame 33 constituting a main member of the latent image carrier unit 32 is provided with another member (not shown) on the back side of the paper surface in FIG. 2 (not shown), and these members are opposed to each other. Are connected to each other by a stay (not shown) to form one structure. The shaft 2 of the support roller 2 is
J, a shaft 3J of the support roller 3, a shaft 4J of the primary transfer opposing roller 4, and a shaft 35J of the tension roller 35 are attached.

The tension roller 35 has its shaft 35J slidably fitted along a groove 36 formed in the frame 33. The direction of the groove 36 is the normal direction of the latent image carrier 1. A spring 37 is provided in the groove 36 to urge the shaft 35J in a direction to push it out. The elasticity of the spring 37 causes the tension roller 35 to apply a constant tension to the latent image carrier 1.

The frame 33 and the members attached to the frame 33 are collectively
No. 2. The latent image carrier unit 32 having such a configuration is independently detachable from the color image forming apparatus main body.

Similar to the latent image carrier unit 32, a similar frame is formed around the intermediate transfer body 5 though not shown, and the frame has support rollers 6, 7, and 2 attached thereto. The intermediate transfer unit 34 is provided as a whole by including the next transfer opposing roller 8 and the tension roller 11. The intermediate transfer body unit 34 is also detachable from the color image forming apparatus main body independently.

As described above, the latent image carrier unit 32 and the intermediate transfer unit 3 are attached to the color image forming apparatus main body.
4 is independently detachable so that the latent image carrier 1
And the intermediate transfer body 5 can be taken out of the color image forming apparatus by itself, and the latent image carrier unit 32, the intermediate transfer body unit 34, etc. taken out in this way, and the color image forming apparatus main body left after taking out With regard to the above members, the maintenance around the target maintenance location is removed, so that maintenance can be performed very easily.

When the latent image carrier unit 32 and the intermediate transfer unit 34 are mounted on the main body of the color image forming apparatus, the primary transfer opposing roller 4 includes the primary transfer roller 30,
The state in which the intermediate transfer belt 5 is pressed against the intermediate transfer belt 5 stretched with a predetermined tension between the intermediate transfer belt 31 and the latent image carrier 1 is maintained as described above. The transfer region configured as the region is stably formed.

It is considered appropriate that the contact area between the latent image carrier belt and the intermediate transfer belt is set to the several mm in order to ensure stable transfer characteristics. The contact area between the belt and the intermediate transfer belt can be set and maintained at several mm, such a transfer area can be formed stably, and a stable image can always be output.

[2] Example Corresponding to Claims 2 to 4 In the color image forming apparatus shown in FIGS. 1 and 2, if the direction in which the latent image carrier unit 32 is attached to and detached from the color image forming apparatus main body and the color When the direction of attachment / detachment of the intermediate transfer body unit 34 from the image forming apparatus main body is parallel to the longitudinal direction of the shaft 2J of the roller 2 supporting the latent image carrier, there is no problem. The unit 32 and the intermediate transfer unit 34 can be detached.

However, due to the layout of various members constituting the color image forming apparatus, as described above, the shaft 2J
In some cases, a direction parallel to the longitudinal direction of the shaft cannot be set as the attaching / detaching direction.

In such a color image forming apparatus, the intermediate transfer between the plurality of primary transfer rollers 30 and 31 is perpendicular to the longitudinal direction of the roller 2 supporting the latent image carrier 1 and between the primary transfer rollers 30 and 31. The latent image carrier unit 32 is movably guided in an arbitrary attachment / detachment direction different from the normal direction of the body belt 1, for example, the left / right direction in FIG. Must be more removable.

In this embodiment, the direction of attachment and detachment of the latent image carrier unit 32 is vertical. In this vertical direction, as is clear from FIG. 1, there is only the paper output tray 26, and there are relatively few obstructions when pulling out the latent image carrier unit 32 as compared with the other directions. This is because it is sufficient to adopt a configuration in which the cover member that constitutes the paper board 26 can be removed.

As described above, although there is no problem in relation to the main body of the color image forming apparatus, the latent image carrier unit 32
Is simply guided linearly in the vertical direction by a guide means so that the primary transfer opposing roller 4 is attached to the primary transfer rollers 30 and 1 in the first transfer section 29 as shown in FIG.
Since the primary transfer opposing roller 4 interferes with the primary transfer roller 30 at the time of attachment / detachment, the attachment / detachment operation itself cannot be performed in extreme cases. Alternatively, the contact between the primary transfer opposing roller 4 and the primary transfer roller 30 may damage the surface of the latent image carrier 1 or the intermediate transfer member 5 and damage the image.

In such a state that it cannot be detached due to interference,
Alternatively, in order to avoid problems caused by scratches on the surface of the latent image carrier 1 or the intermediate transfer body 5 due to contact, in this embodiment, each of the latent image carrier unit 32 and the intermediate transfer body unit 34 is configured as follows.

First, with respect to the latent image carrier unit 32, during the operation of attaching and detaching the latent image carrier unit 32 to and from the main body of the color image forming apparatus, the primary transfer opposing roller 4
Is configured to be movable in the horizontal direction on the frame 33. That is, the primary transfer opposing roller 4 can be moved between a projecting position that can interfere with the primary transfer roller 30 and a retracted position that cannot interfere.

More specifically, as shown in FIG. 3, the horizontal direction is perpendicular to the longitudinal direction of the shaft 2J and is perpendicular to the vertical direction VV which is the direction in which the latent image carrier unit 32 is attached and detached. A long elongated hole 40 is formed in the frame 33 in the direction HH, and the shaft 4J of the primary transfer opposing roller 4 is slidably fitted in the elongated hole 40. The position of the long hole 40 and the size in the longitudinal direction are such that the primary transfer opposing roller 4 is
The shaft 4J is formed with a size sufficient to enable the movement of the shaft 4J between a protruding position where it can interfere and a retracted position where it cannot interfere.

More specifically, as shown in FIG. 4, a bearing 41 is provided at a portion of the shaft 4J that fits into the elongated hole 40, and the shaft positioning member 42 is sandwiched between the bearings 41 so as to sandwich the frame 33. , 43 were provided. Further, a shaft 44 is implanted directly below the elongated hole 40 and on the inner surface of the frame 33, and an elastic spring 45 is applied between the shaft 44 and a bearing 42 provided on the shaft 4J, thereby connecting the shaft 4J. A long hole 4 with room in the vertical direction
In this case, the lower edge is pressed and biased. In this configuration, the primary transfer opposing roller 4 is free to rotate with respect to the frame 33, and is rotatable as the latent image carrier 1 rotates. The other end of the shaft 4J has the same configuration.

In a state where the latent image carrier unit 32 is removed from the main body of the color image forming apparatus, as shown in FIG. 3, the latent image carrier is elastically biased by the spring 37 for urging the tension roller 35. 1 is tensioned with a constant tension, and 1
The next transfer opposing roller 4 is in a state where the shaft 4J is abutted on the right end of the elongated hole 40. Under this state, the primary transfer opposing roller 4 is retracted substantially inside the frame 33. However, by applying some external force, the shaft 4J is
It is possible to move within a range that hits the left end of 0.

The structure of the intermediate transfer unit 34 will be described with reference to FIG. In FIG. 5, a frame (a frame corresponding to the frame 33 of the latent image carrier unit 32) that supports the support rollers 6, 7 and the secondary transfer opposing roller 8, the tension roller 11, and the like is not shown. A guide member 50 is provided integrally with the frame.

The guide member 50 has a groove 6 for guiding the shaft 4J.
0 is formed. The upper portion of the groove 60 is opened to communicate with the outside world, and is formed larger than the shaft diameter of the shaft 4J so that the shaft 4J can be easily inserted into the groove 60.

More specifically, the groove 60 has a bottom edge 60-3.
And two parts of two opposing side edges 60-1 and 60-2. Of these two side edges 60-1, 60-2, the side edge 60-1 is a side edge located on the left side closer to the intermediate transfer member 5, and the first side edge 60a and the second side edge from above. 60b and a third side edge 60d. The side edge 60-2 is a side edge located on the right side far from the intermediate transfer body 5, and includes a first opposing side edge 60A, a second opposing side edge 60B, and a third opposing side edge 60C from above.

Regarding the side edge 60-1, the first side edge 60a is 1
This is a linear portion that is provided at the same height as the next transfer roller 30 and shifted in the horizontal direction, and extends in the vertical direction. An inclined surface 70 is formed adjacent to the upper portion of the first side edge 60a. Below the first side edge 60a, there is a third side edge 60c via a second side edge 60b inclined to the left. The third side edge 60c has a linear shape along the vertical direction, and is located closer to the intermediate transfer member 5 than the first side edge 60a.

Regarding the side edge 60-2, the first opposing side edge 60A
Is formed in a straight line along the vertical direction at an interval sufficiently larger than the diameter of the shaft 4J to facilitate introduction of the shaft 4J. Below the first opposing side edge 60A, there is a third opposing side edge 60C via a second opposing side edge 60B inclined to the left. The lower portions of the third opposing side edge 60C and the third side edge 50c are in contact with the common bottom edge 60-3.

As described with reference to FIG.
It is movable within the stroke range. And it is guided and positioned by the groove 60 in the range of this stroke.
When the latent image carrier unit 32 is separated from the color image forming apparatus main body, the shaft 4J is located at an unspecified position on the long hole 40. When the latent image carrier unit 32 is mounted on the main body of the color image forming apparatus, an engaging portion (not shown) of the latent image carrier unit 32 is attached to a vertical guide (not shown) provided on the main body side of the color image forming apparatus. Engage,
Under this engaged state, the latent image carrier unit 32 is lowered.

In a state where the shaft 4J is still located above the groove 60, no matter where the shaft 4J is located on the long hole 40, the latent image carrier unit 32 is further lowered. To ensure that it is introduced into the groove 60,
The horizontal formation position of the elongated hole 40 is such that the left end of the elongated hole 40 is located at least to the left of the third opposing side edge 60c. Therefore, the shaft 4J is located above the inclined surface 70, and the right end of the elongated hole 40 is located on the left side of the first side edge 60A, that is, above the second opposed side edge 60B.

When the latent image carrier unit 32 is lowered, for example, if the shaft 4J is located above the inclined surface 70, it is guided by the inclined surface 70 and is introduced into the groove 60. If it is at the right end of 40, that is, immediately above the groove 60, it is directly introduced into the groove 60.

When the latent image carrier unit 32 is further lowered, the shaft 4J is restricted by the first side edge 60a in a section corresponding to the first side edge 60a, so that the shaft 4J cannot approach the primary transfer roller 30. Accordingly, in this section, the shaft 4J sets the primary transfer opposing roller 4 to a retracted position where the primary transfer roller 4 cannot interfere with the primary transfer roller 30.

When the shaft 4J descends beyond the section corresponding to the first side edge 60a, the shaft 4J is guided by the second opposing side edge 60B, and the third opposing side edge 60c and the third opposing side edge 60c.
The lower edge 6 is inserted into the portion facing the side edge 60C.
It is held at the position where it abuts on 0-3.

Guide means (not shown) in the vertical direction of the latent image carrier unit 32 provided in the main body of the color image forming apparatus is provided with stopper means for stopping the lowering of the latent image carrier unit 32. The lowering of the image carrier unit 32 is prevented at a position where the shaft 4J abuts on the bottom edge 60-3, and is locked and held by appropriate holding means.

At this time, the primary transfer opposing roller 4 is pressed against the latent image carrier 5 tensioned by a predetermined tension between the primary transfer roller 30 and the primary transfer roller 31, as shown in FIG. And a state in which the latent image carrier 1 and the intermediate transfer member 5 are in contact with each other, and a predetermined transfer area is formed.
The primary transfer opposing roller 4 is at the projecting position.

When the latent image carrier unit 32 is removed from the color image forming apparatus main body, the operation reverse to the above is performed, and the lock of the holding means is released. Lift along the guide provided on the forming apparatus body. With this ascent operation, the shaft 4J is guided by the groove 60.

That is, from the position regulated by the third side edge 60c (the protruding position where the primary transfer opposing roller 4 can interfere with the primary transfer roller 30), the second side edge 60b passes through the first side edge 60a. The position moves to a regulated position (a retract position where the primary transfer opposing roller 4 cannot interfere with the primary transfer roller 30), and
The next transfer opposing roller 4 is raised around the primary transfer roller 30.

As described above, only by the attaching / detaching operation of moving the latent image carrier unit 32 up and down along the guide means of the color image forming apparatus, the primary transfer roller 4 is automatically moved to the projecting position and the retreating position in conjunction with this. You can switch to In this switching process, the primary transfer roller 4 moves, but the tension of the latent image carrier 1 is kept constant by the tension roller 35J.

Here, the elongated hole 40 is provided in the latent image carrier unit 32 and
The primary transfer opposing roller 4 is moved so as to be able to take a projecting position that can interfere with the primary transfer roller 30 and a retracted position that cannot interfere with the primary transfer roller 30.
1 is an example of a supporting means for supporting the shaft portion 4J of the first embodiment in a reciprocating manner. The groove 60 engages with the shaft 4J in accordance with the attachment / detachment operation of the latent image carrying unit 32 in the process of attaching / detaching the latent image carrying unit 32 to / from the main body of the color image forming apparatus. It is an example of a guide member for moving the shaft portion 4J between the guide members.

The spring 45 presses the shaft 4J against the lower edge of the elongated hole 40 at least in a state where the latent image carrier unit 32 is removed from the main body of the color image forming apparatus. When the latent image carrier unit 32 is mounted on the color image forming apparatus main body, the position of the latent image carrier unit 32 in the vertical direction by the stopper provided on the color image forming apparatus main body is also determined. As you can see, for example, slot 4
When the stop position of the guide member on the color image forming apparatus main body side is set such that the lower edge of the lower edge 0 and the lower edge 60-3 are at the same level, the spring 45 has an elongated hole with a clearance in the vertical direction. The shaft 4J is securely brought into contact with the lower edge of the long hole 40 within 40, or, for example, the lower edge of the long hole 40 is located at a level slightly higher than the bottom edge 60-3. In the case where the stop position of the guide member on the color image forming apparatus main body side is set as described above, also in this case, the shaft 4J is securely fitted to the lower edge of the long hole 40 in the long hole having a space in the vertical direction. Contact.

Further, for example, when the stop position of the guide member on the color image forming apparatus main body side is set such that the lower edge of the long hole 40 is at a level slightly lower than the lower edge 60-3. The spring 45 ensures that the shaft 4J abuts against the bottom edge 60-3. In any case, the shaft 4 in the elongated hole 40
Even if a space is provided in the vertical direction of the elongated hole 40 with respect to the diameter of the shaft 40J to facilitate the movement of the elongated hole 40, the action of the spring 45 allows the bottom edge and / or bottom edge 6
The shaft 4J can be reliably brought into contact with a fixed reference position such as 0-3, so that the primary transfer roller 4 is
It can be located at a certain position between 0 and 31 under certain conditions. As described above, the spring 45 is an example of a press-contact member that presses the shaft 4J against the support means and / or the guide member.

In this embodiment, the latent image carrier 1 and the intermediate transfer member 5 are arranged in a substantially vertical direction.
And the case where each unit of the intermediate transfer body 5 is detachable in the vertical direction has been described, but the latent image carrier 1 and the intermediate transfer body 5 are arranged in a substantially horizontal direction, and these latent image carrier 1
Also, the case where each unit of the intermediate transfer member 5 is detachable in the horizontal direction can be applied according to the above-described example.

[0072]

According to the first aspect of the present invention, since the latent image carrier and the intermediate transfer body are constituted by endless belts, and the transfer area for securely contacting both belts is constituted, the image quality is good and the size is small. Color image forming apparatus.

According to the second aspect of the present invention, since the latent image carrier unit is detachable from the main body of the color image forming apparatus, maintenance work is easy.

According to the third aspect of the present invention, since the longitudinal direction of each belt portion of the latent image carrier and the intermediate transfer member is substantially vertical, the required space in the horizontal direction of the color image forming apparatus is reduced. can do.

According to the fourth aspect of the present invention, in the operation of attaching and detaching the latent image carrier unit from the main body of the color image forming apparatus, the interference between the primary transfer opposing roller and the primary transfer roller is avoided by a simple operation. An appropriate transfer area can be easily obtained while preventing the surface of the intermediate transfer body belt from being damaged. In this transfer area, a contact area of several mm can be secured, so that stable transfer characteristics are always secured. As a result, a stable image can be output.

According to the fifth aspect of the present invention, the primary transfer opposing roller can be positioned at a predetermined position by the function of the pressure contact member, so that a predetermined transfer area can be reliably obtained.

According to the sixth aspect of the present invention, the pressing means can be obtained by simple means.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a color image forming apparatus capable of forming a full-color image according to the present invention.

FIG. 2 is a partial front view showing the latent image carrier unit and the intermediate transfer unit when the latent image carrier unit is mounted on the color image forming apparatus.

FIG. 3 is a front view of the latent image carrier unit.

FIG. 4 is a partial cross-sectional view of a support portion of a primary transfer facing roller with respect to a frame.

FIG. 5 is a schematic front view of the intermediate transfer body unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Latent image carrier 4 Primary transfer opposing roller 5 Intermediate transfer member 40 Slot (as a support means) 60 Groove (as a guide member)

Continued on the front page F-term (reference) 2H030 AA07 AD02 AD03 AD04 AD05 BB02 BB23 BB42 BB44 BB46 BB54 2H032 AA05 AA15 BA02 BA03 BA09 BA19 BA21 BA23 BA26 BA30 2H071 BA03 BA13 BA15 BA16 BA27 BA36 CA02 CA05 DA06 DA09 DA09 DA09 EA18

Claims (6)

[Claims] A developing device for developing an electrostatic latent image formed on the latent image carrier with a plurality of color developers containing at least toner, wherein a toner image formed on the latent image carrier is formed on the latent image carrier. A color image forming apparatus having a function of transferring the toner image on the intermediate transfer member onto a transfer material after transferring the toner image on the intermediate transfer member, and further fixing the toner image on the transfer material by a fixing unit; The image carrier and the intermediate transfer body are both endless belts, and each of the latent image carrier and the intermediate transfer body is independently detachable from the apparatus main body to form an independent latent image carrier unit and an intermediate transfer body unit. A plurality of primary transfer units that are provided, and that are capable of rotating a primary transfer unit that transfers a toner image formed on the latent image carrier onto the intermediate transfer body, following the rotation of the intermediate transfer body Roller and rotation of the latent image carrier Accordingly, the primary transfer opposing roller is configured to be rotatable, and the primary transfer opposing roller is stretched with a predetermined tension between the plurality of primary transfer rollers. A color image forming apparatus, wherein a transfer area is formed by being pressed against the intermediate transfer belt. 2. A color image forming apparatus according to claim 1, wherein said roller is arranged between said plurality of primary transfer rollers in a direction perpendicular to an axial longitudinal direction of a roller for supporting said latent image carrier. A color image wherein the latent image carrier unit is movably guided in an arbitrary attaching / detaching direction different from the normal direction of the intermediate transfer belt so that the latent image carrier unit is detachable from the apparatus main body. Forming equipment. 3. The color image forming apparatus according to claim 2, wherein the belt-like portions of the latent image carrier and the intermediate transfer member are stretched in a substantially vertical direction, respectively.
2. The color image forming apparatus according to claim 1, wherein the mounting direction is a vertical direction. 4. A color image forming apparatus according to claim 1, wherein the primary image transfer roller is provided on the latent image carrier unit and the primary image transfer roller can interfere with the primary image transfer roller. Supporting means for reciprocatingly supporting the shaft of the primary transfer opposing roller so as to be able to take a retracted position which cannot interfere with the position; a tension roller for applying a constant tension to the latent image carrier; The latent image holding unit is provided in the intermediate transfer unit, and engages with the shaft portion in accordance with the attaching / detaching operation of the latent image carrying unit in a process of attaching / detaching the latent image carrying unit to / from the apparatus main body. A guide member for moving the shaft portion between them. 5. The color image forming apparatus according to claim 4, further comprising a pressing member for pressing said shaft portion against said support means and / or said guide member. 6. A color image forming apparatus according to claim 5, wherein said press-contact member comprises a contractile spring provided between said shaft portion and said latent image carrier unit. Forming equipment.