JP2001249508A - Image forming unit and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming unit where making the unit small and bringing the cost down is possible and where only a member that is necessary can be exchanged and an image forming device utilizing it. SOLUTION: In the image forming unit that can be attached to or detached from an image forming device main body, a photoreceptor drum unit 20 provided with the photoreceptor drum 1 and an intermediate transfer belt unit 21 provided with an intermediate transfer belt 5a where an image on the photoreceptor drum 1 is transferred, the photoreceptor drum unit 20 and the intermediate transfer belt unit 21 are constituted to be able to be attached or detached.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming unit used for a copying machine or a printer using an electrophotographic system, and an image forming apparatus for forming an image on a transfer material using the same.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, an image is formed by transferring a toner image formed on a photosensitive drum as an image carrier to a transfer material. 2. Description of the Related Art There has been used a device having a configuration in which toner images of respective colors sequentially formed on a body drum are superimposedly transferred onto an intermediate transfer member, and the color images are collectively transferred onto a transfer material. In this case, in order to facilitate the handling of the deteriorated and consumable members of the photosensitive drum and the like, those which are unitized and detachable from the apparatus main body have been widely used.

For example, in an apparatus disclosed in Japanese Patent Application Laid-Open No. 8-137181 (hereinafter referred to as "conventional apparatus A"), a photosensitive unit and an intermediate transfer unit are configured as independent units, and a large movable frame is provided. Is rotated to the front of the apparatus, and the photosensitive unit and the intermediate transfer unit are inserted from above.

Then, on the upper surface of the projection of the intermediate transfer belt,
A photoreceptor unit in which a photoreceptor drum and a waste toner storage box are integrated is provided. Waste toner on the photoreceptor drum is scraped off by a cleaning blade and stored in a waste toner box on the back surface. Waste toner on the intermediate transfer belt is also scraped off by another cleaning blade, transported to a lower portion of the first transport pipe by a transport coil, and further stored by a screw in the first transport pipe. It is transported to the upper part of the box. Thereafter, the sheet is transported by the transport coil in the second transport pipe, and is finally stored in the waste toner storage box.

[0005] Further, since the connecting portion between the second pipe and the waste toner storage box is a separate unit, which is detachable, the shutter is opened and closed during attachment and detachment to prevent waste toner from spilling. .

Another conventional color image forming apparatus using an intermediate transfer member is disclosed in Japanese Patent Application Laid-Open No. H11-30944.
As disclosed in Japanese Patent Application Laid-Open No. H10-177329, there has been proposed an apparatus in which a photoreceptor belt, an intermediate transfer belt, and a waste toner storage box are integrated (hereinafter, referred to as "conventional apparatus B").

In the conventional apparatus B, a photoreceptor belt and a waste toner collecting box are arranged on a lower surface of a projection of the intermediate transfer belt. Further, similarly to the conventional device A,
The large movable frame is pivotally opened to the front of the apparatus, and an image forming unit in which an intermediate transfer body, a photoconductor, and a waste toner storage box are integrated is inserted from above.

[0008]

However, the above-described conventional color image forming apparatus has the following problems.

In the conventional apparatus A, since the intermediate transfer member and the photosensitive member are separate units, and two units are present, it takes time and effort for the user to replace the unit. In addition, the leakage of waste toner from the waste toner connecting portion between the units and the occurrence of a removal / insertion procedure at the time of attaching / detaching the units also cause usability to deteriorate. Further, since there are two types of units, the entire apparatus becomes large, the number of parts increases, and the cost increases.

Further, a large opening for attaching and detaching two types of image forming units is required, and the entire front surface of the apparatus is rotated and opened. Is hard work for
There is a problem that a large space and frame rigidity are required for the rotating mechanism, and the cost is further increased.

On the other hand, in the conventional apparatus B, the photosensitive member belt, the intermediate transfer member belt and the waste toner container constitute an integrated image forming unit. Only one image forming unit needs to be replaced. Therefore, usability is improved as compared with the conventional device A. However, when one of the photoreceptor belt and the intermediate transfer member belt has reached the end of its life, even if the other is usable, it must be replaced.
This imposes a cost burden on the user.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an image forming unit which can be reduced in size and cost and which can replace only necessary members, and an image using the same. A forming apparatus is provided.

[0013]

In order to achieve the above object, a typical configuration according to the present invention is an image forming unit detachable from an image forming apparatus main body, comprising: a first unit having an image carrier; A second unit having an intermediate transfer member onto which an image on the image carrier is transferred, wherein the first unit and the second unit are configured to be detachable.

In the above configuration, the first unit and the second unit are attached to and detached from the main body of the image forming apparatus in a state where the first unit and the second unit are connected to each other, so that the image carrier and the intermediate transfer body are integrally treated, so that the maintenance performance is improved. If one of the image carrier and the intermediate transfer member has reached the end of its service life, it is possible to replace only the member whose service life has expired by separating the two units, thereby reducing costs. Can be.

[0015]

Next, an image forming unit and an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.

[First Embodiment] FIG. 1 is an explanatory longitudinal sectional view showing a schematic configuration of a four-color full-color laser beam printer in an electrophotographic image forming apparatus A according to a first embodiment.

<< Overall Configuration of Image Forming Apparatus >> The photosensitive drum 1 as an image carrier is rotated in the direction of an arrow in FIG. 1 (counterclockwise) in synchronization with the rotation of an endless intermediate transfer belt 5a as an intermediate transfer body. The surface of the photosensitive drum 1 is uniformly charged by a charging roller 2 serving as a charging device, and a yellow image is irradiated with light by an exposure unit 3 to form a yellow electrostatic latent image on the photosensitive drum 1. Form. Simultaneously with the formation of the electrostatic latent image, the developing device 4 is driven to dispose the yellow developing unit 4Y at the developing position, and the photosensitive drum 1 is moved so that the yellow toner adheres to the electrostatic latent image on the photosensitive drum 1. A voltage having the same polarity as the charging polarity and substantially the same potential is applied to cause the yellow toner to adhere to the electrostatic latent image for development. Thereafter, a voltage having a polarity opposite to that of the toner is applied to a pressing roller (primary transfer roller) 5j of the intermediate transfer belt 5a to transfer the yellow toner image on the photosensitive drum 1 to the intermediate transfer belt 5j.
Primary transfer onto a.

When the primary transfer of the yellow toner image is completed as described above, the next developing unit rotates and moves to the developing position facing the photosensitive drum, and the magenta and cyan toners are moved in the same manner as in the case of yellow. , And formation of an electrostatic latent image for each color of black, each color developing device 4M,
Development and primary transfer by 4C and 4BK are sequentially performed, and four color toner images are superimposed on the intermediate transfer belt 5a.

During this time, the secondary transfer roller 11 is not in contact with the intermediate transfer belt 5a. At this time, the charging roller 5f as a cleaning charging unit is also connected to the intermediate transfer belt 5a.
Is in a non-contact state.

After the formation of the four color toner images on the intermediate transfer belt 5a, the secondary transfer roller 11 is pressed against the intermediate transfer belt 5a (the state shown in FIG. 1).
feed roller 7 as a conveying means in synchronization with the rotation of
b, the transfer material transported from the transfer material cassette 7a by the transport roller pair 7c and waiting at a predetermined position near the registration roller pair 7d is sent out to the nip portion between the intermediate transfer belt 5a and the secondary transfer roller 11.

Immediately before the registration roller pair 7d, a pre-registration sensor 14 which detects the leading end of the transfer material S, shuts off the rotational driving force of the registration roller pair 7d, and waits the transfer material S at a predetermined position. Is provided.

Further, a voltage having a polarity opposite to that of the toner is applied to the secondary transfer roller 11, so that the toner image on the intermediate transfer belt 5a is secondarily transferred onto the surface of the transfer material S which has been conveyed together. I will do it.

The transfer material S thus secondary-transferred as described above
Reaches the fixing device 8 via the conveyor belt unit 12, where the toner images of a plurality of colors are fixed,
The sheet is conveyed along the sheet ejection guide 15 and is ejected to the sheet ejection tray 10 above the color image forming apparatus A by the ejection roller pair 9 to complete the image formation.

On the other hand, after the secondary transfer, the cleaning charging roller 5f is pressed against the intermediate transfer belt 5a, and charges the residual toner remaining on the intermediate transfer belt with a charge opposite to that at the time of transfer (in the opposite direction to the normal charge polarity of the toner). (Polar charge). In the collecting means, the residual toner to which the charge of the opposite polarity has been applied as described above is electrostatically attached to the photosensitive drum 1 by the primary transfer roller 5j, and thereafter collected by the cleaning drum 6 for the photosensitive drum. You. Then, the collected residual toner follows a conveyance path to be described later as waste toner and is conveyed to a waste toner box.
Collected and accumulated at 16.

When an image is continuously formed on a plurality of transfer materials, the residual toner charged by the cleaning charging roller 5f is electrostatically transferred from the intermediate transfer belt 5a to the photosensitive drum 1 at the same time. The toner image for the next transfer material formed on the photosensitive drum 1 is primarily transferred to the intermediate transfer belt 5a. Thereby, the throughput of image formation can be improved.

{Image Forming Unit} Next, the structure of the image forming unit integrated with the photosensitive drum and the intermediate transfer belt that is attached to and detached from the image forming apparatus will be described in detail.

FIG. 2 is an explanatory longitudinal sectional view showing a schematic configuration of the image forming unit. FIG. 3 is an explanatory longitudinal sectional view of the image forming unit viewed from the side opposite to FIG. 2, and FIG. 4 is an arrow B in FIG. FIG. 4 is an explanatory cross-sectional view of the waste toner conveying passage viewed from the direction.

2 to 4, the image forming unit 5
Has a photoreceptor drum unit 20 disposed on the upper projection surface of the intermediate transfer belt unit 21 and a waste toner box disposed on the lower projection surface of the intermediate transfer belt unit 21. Further, the belt driving roller 40 of the intermediate transfer belt unit 21 is provided with a cleaning charging roller unit 23 for applying a charge opposite to that at the time of transfer to the residual toner on the intermediate transfer belt.

The photosensitive drum unit 20 has the photosensitive drum 1 rotatably held at both ends thereof by bearings (not shown), and a predetermined rotational driving force from the apparatus main body via a coupling 24 (see FIG. 3) at the right end. Is transmitted.

A charging roller 2 is pressed against the photosensitive drum 1 by a compression spring 26 with a predetermined force via bearings 25 at both ends, and is driven to rotate. At least one of the bearings 25 is formed of a conductive member, and a predetermined charging bias voltage is applied to the charging roller 2 to uniformly charge the surface of the photosensitive drum 1.

Further, a cleaning blade 6 is provided at a predetermined position on the photosensitive drum 1 to remove the residual toner on the intermediate transfer belt to which the above-described reverse charge has been applied.
It is configured to be collected above and scraped off together with the residual toner on the photosensitive drum 1. The scraped-off waste toner is prevented from falling onto the intermediate transfer belt 5a by the squeeze sheet 27, and the waste toner accumulated on the bottom of the photosensitive drum frame 29 is conveyed to the right side when viewed from the front of the apparatus by the rotation of the screw 28. (Direction of arrow C in FIG. 4).

Thereafter, the waste toner is supplied to the right side of the photosensitive drum unit 20 by the screw 28 (as viewed from the front side of the apparatus).
, And slide down and accumulate in the waste toner box 16. The photosensitive drum unit 20 is also provided with a drum shutter 19 that opens and closes in conjunction with the operation of attaching and detaching the photosensitive drum unit to and from the image forming apparatus main body.

Next, the configuration of the intermediate transfer belt unit 21 will be described. The intermediate transfer belt 5a is suspended around a frame 45 including a handle 61 by a driving roller 40 and a driven roller 41.

The driving roller 40 is rotatably held at both ends by bearings (not shown), and a predetermined rotational driving force is transmitted from the apparatus main body via a coupling 42 (see FIG. 3) at the right end. I have. Also, bearings at both ends of the driven roller
A compression spring 44 is provided on 43 to apply a predetermined tension to the intermediate transfer belt 5a.

A primary transfer roller 5j is provided at a position facing the photosensitive drum 1 with the intermediate transfer belt 5a interposed therebetween. The primary transfer roller 5j is pressed by a compression spring 47 with a predetermined force via bearings 46 at both ends, and is driven. It is designed to rotate.

At least one of the bearings 46 is formed of a conductive member. By applying a predetermined charging bias voltage to the primary transfer roller 5j, the toner on the surface of the photosensitive drum 1 is primarily transferred onto the intermediate transfer belt 5a. Is done.

At a position facing the intermediate transfer belt driving roller 40, a cleaning charging roller portion 23 for applying a charge opposite to that at the time of transfer to the residual toner on the intermediate transfer belt is provided.
Is provided.

The cleaning charging roller 5f has bearings at both ends.
The compression spring 52 press-contacts with a predetermined force via 51, and is driven to rotate. Then, at least one of the bearings 51 is formed of a conductive member, and by applying a voltage opposite to that at the time of transfer to the cleaning charging roller 5f,
The remaining toner on the intermediate transfer belt 5a is given a charge opposite to that at the time of transfer, is electrostatically attracted and collected on the drum surface by the photosensitive drum 1, and is accumulated in the waste toner box 16 as described above.

With the above construction, an image forming unit integrated with a developing unit having a size comparable to that of a conventional monochrome cartridge and a small-sized and low-cost intermediate transfer member and photosensitive drum similar to a photosensitive cartridge integrated process cartridge. And it is also possible to reduce the size of the image forming apparatus body using the same.

Further, by using the cleaning charging roller 5f, the waste toner boxes for the photosensitive drum and the intermediate transfer belt can be combined into one, and the layout restriction of each member in the unit can be reduced. it can.

{Unit Configuration of Image Forming Unit} Next, the frame configuration of the image forming unit 5 will be described in detail. The frame configuration is roughly divided into two. First, as shown in FIG. 4, the first unit includes a photosensitive drum 1, a right bearing 80, a left bearing 81, a charging roller 2, and a photosensitive drum frame 29 which is integrated with the waste toner box 16.
This is a photosensitive drum unit 20 (a portion surrounded by a bold two-dot chain line in FIG. 4) composed of the cleaning blade 6, the screw 28, and the drum shutter 19 as main components. Further, as shown in FIG. 2, the second unit has an intermediate transfer belt 5a suspended around a drive roller 40 and a driven roller 41 on an intermediate transfer body frame 45, and the intermediate transfer belt 5a is opposed to the photosensitive drum 1. Inside the primary transfer roller 5j,
The driving roller 40 is the intermediate transfer belt unit 21 in which the cleaning charging roller 5f is also disposed.

As shown in FIGS. 2 and 3, the two units have projections 71 provided on the left and right ends of the photosensitive drum frame 29 in positioning holes 72 provided in the intermediate transfer member frame 45, respectively. On the other hand, a hook 73 of a snap-fit type hook portion provided at the center in the width direction of the photosensitive drum frame 29 is engaged with a lock hole 74 of the intermediate transfer member frame 45.
It is fitted and connected.

Here, the positioning hole 72 and the lock hole 74 provided in the intermediate transfer body frame 45 are larger than the projection 71 provided in the photosensitive drum frame 29 and the hook 73 of the hook by a predetermined amount. A hole is formed, and a predetermined amount of relative position movement between the photosensitive drum unit 20 and the intermediate transfer belt unit 21 is possible. Also,
The positioning hole 72 is provided with a tapered portion 72a (see FIG. 6) so that it can be easily attached and detached.

In the above configuration, as shown in FIG. 3, the hook claw 73 of the photosensitive drum unit 20 is pushed in the direction of arrow D to disengage it from the lock hole 74 of the intermediate transfer belt unit 21.
As shown in FIG. 5, by rotating the photosensitive drum unit 20 in the direction of arrow E, as shown in FIGS. 6 and 7,
The photosensitive drum unit 20 and the intermediate transfer belt unit 21 can be divided.

When the two units 20 and 21 are connected to each other, the projection 71 of the photosensitive drum unit 20 is reversed.
Into the positioning hole 72 of the intermediate transfer belt unit 21,
By rotating the hook claw 73 into the lock hole 74 by rotating in the direction opposite to the arrow E in FIG. 5, the two units 20 and 21 are connected.

Since the photosensitive drum unit 20 and the intermediate transfer belt unit 21 are separable as described above, the life has expired when only the photosensitive drum 1 or only the intermediate transfer belt 5a has reached the end of its life. Only the unit can be replaced. Therefore, when the life of the photosensitive drum 1 and the life of the intermediate transfer belt 5a are different, the cost burden on the user is reduced.

{Mounting Means of Unit to Apparatus Main Body} Next, a description will be given of a configuration for attaching and detaching the image forming unit 5 to and from the image forming apparatus main body A and positioning and fixing the image forming unit 5 to a predetermined position with reference to FIG.

When the upper lid 60 of the main body A of the color image forming apparatus is opened, it is provided on a support portion 82 for supporting a photosensitive drum bearing.
Coupling for transmitting rotational driving force to photoconductor drum 1
24 (see FIG. 3) and a coupling 42 (see FIG. 3) which is provided on a support portion 83 which supports the bearing portion of the intermediate transfer belt driving shaft, and transmits rotational driving force to the intermediate transfer belt driving roller. 3) are respectively slid in the axial direction and retracted (disconnected state). It should be noted that a well-known configuration may be used for the retraction configuration itself of the coupling interlocking with the upper lid 60.

A guide rail 84 for the photosensitive drum and a guide rail 85 for the intermediate transfer body are provided on both sides of the apparatus body with a step γ. This step γ is the step γ between the drum bearings 80 and 81 of the image forming unit and the bearings 86 and 87 of the intermediate transfer belt driving roller, as shown in FIG.

The right and left photosensitive drum bearings 80 and 81 of the image forming unit 5 are connected to the photosensitive drum guide rails 84.
The right and left bearings 86 and 87 of the intermediate transfer belt drive roller and the projections 88 and 89 provided on the left and right side covers are placed on the intermediate transfer member guide rail 85 and inserted while sliding.

Finally, the right and left bearings 80 and 81 of the photosensitive drum fall into the supporting portion 82 for supporting the photosensitive drum bearing, and the right bearing 86 and the left bearing 87 of the intermediate transfer belt driving roller drive the intermediate transfer belt. Support part 83 that supports the shaft bearing part
The projections 88 and 89 provided on the left and right side covers of the image forming unit respectively fall into the positioning grooves 90. As shown in FIG. 8, the projections 88 and 89 are respectively formed by torsion coil springs 91, 92 and 93 on the frame of the apparatus main body. It is pressed against the positioning and fixed.

With the above configuration, the upper lid 60
The image forming unit in which the photosensitive drum unit 20 and the intermediate transfer belt unit 21 are connected can be easily attached and detached simply by opening the cover, and maintenance such as jam (paper jam) processing and replacement of the image forming unit can be easily performed. it can.

Further, since the positional relationship between the photosensitive drum unit 20 and the intermediate transfer belt unit 21 is configured to be relatively movable by a predetermined amount, even if there is a slight dimensional error, the image is formed as described above. When the forming unit 5 is mounted on the image forming apparatus main body, the relative positional relationship between the photosensitive drum 1 and the intermediate transfer belt 5a is fixed at a regular position,
In addition, the positional relationship between them and the image forming apparatus main body also becomes a regular positional relationship. In other words, there is no need to adopt a so-called Oldham coupling which absorbs dimensional errors and absorbs misalignment as in the prior art.
The coupling configuration for transmitting the rotational driving force transmission to each of the components a can be simplified.

In the above-described embodiment, an example is shown in which the photosensitive drum unit 20 and the intermediate transfer belt unit 21 are connected to form an image forming unit. However, the photosensitive drum unit 20 is integrated with the unit housing. It is used in the image forming apparatus of the present invention by being fixed and configured as a unit that can also be used in a normal image forming apparatus, and by configuring the intermediate transfer belt unit 21 to be detachable from the unit housing. An image forming unit may be configured. Also, contrary to the above, the intermediate transfer belt unit
The unit 21 may be integrally fixed to the unit housing, and the photosensitive drum unit 20 may be configured to be detachable from the unit housing.

Even with such a configuration, it is possible to replace only the photosensitive drum or the intermediate transfer member whose life has expired.

[0056]

The present invention is constructed as described above.
By attaching and detaching the first unit and the second unit to and from the image forming apparatus main body in a state where the first unit and the second unit are connected to each other, the image carrier and the intermediate transfer body are integrally handled, thereby improving maintainability. When one of the transfer members reaches the end of its life, the two units are separated from each other, so that only the member whose life has expired can be replaced, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory longitudinal sectional view showing a schematic configuration of a four-color full-color laser beam printer.

FIG. 2 is an explanatory longitudinal sectional view showing a schematic configuration of an image forming unit.

FIG. 3 is an explanatory longitudinal sectional view of the image forming unit viewed from a side opposite to FIG. 2;

FIG. 4 is an explanatory cross-sectional view of the waste toner conveying passage section viewed from the direction of arrow B in FIG. 3;

FIG. 5 is an explanatory diagram illustrating a state where a photosensitive drum unit and an intermediate transfer belt unit are separated.

FIG. 6 is an explanatory sectional view of the separated intermediate transfer belt unit.

FIG. 7 is an explanatory sectional view of a separated photosensitive drum unit.

FIG. 8 is an explanatory diagram of a state in which an image forming unit is attached and detached.

[Explanation of symbols]

 A: Electrophotographic image forming apparatus S: Transfer material 1: Photoconductor drum 2: Charging roller 3: Exposure means 4: Developing device 4Y, 4M, 4C, 4BK: Color developing device 5: Image forming unit 5a: Intermediate transfer belt 5f ... Cleaning charging roller 5j ... Primary transfer roller 6 ... Cleaning blade 7a ... Transfer material cassette 7b ... Supply roller 7c ... Transport roller pair 7d ... Registration roller pair 8 ... Fixing device 9 ... Discharge roller pair 10 ... Discharge tray 11 ... 2 Next transfer roller 12… Conveyer belt unit 13… Back discharge roller pair 14… Before registration sensor 15… Discharge guide 16… Waste toner box 19… Drum shutter 20… Photoconductor drum unit 21… Intermediate transfer belt unit 23… Cleaning charging roller Part 24… Coupling 25… Bearing 26… Compression spring 27… Squeeze sheet 28… Screw 29… Photoconductor Drum frame 40… Belt drive roller 41… Driving roller 42… Coupling 43… Bearing 44… Compression spring 45… Intermediate transfer body frame 46… Bearing 47… Compression spring 51… Bearing 52… Compression spring 60… Top lid 61… Handle 71 … Projecting part 72… Positioning hole 72a… Taper part 73… Claw 74… Lock hole 80… Right bearing 81… Left bearing 82… Support part 83… Support part 84… Guide rail 85… Guide rail 86… Right bearing 87… Left bearing 88, 89 ... Projection 90 ... Positioning groove

Claims (7)

[Claims] 1. An image forming unit detachable from an image forming apparatus main body, comprising: a first unit having an image carrier; and a second unit having an intermediate transfer member onto which an image on the image carrier is transferred. An image forming unit, comprising: the first unit and the second unit detachably configured. 2. An image forming unit according to claim 1, wherein said first unit and said second unit have positioning means for positioning with respect to an image forming apparatus main body. 3. The image forming unit according to claim 1, wherein the first unit or the second unit is provided with a toner box for storing toner collected from the intermediate transfer member. 4. The image forming apparatus according to claim 1, wherein the first unit and the second unit are connected to each other so that a positional relationship between the image carrier and the intermediate transfer member can be relatively moved by a predetermined amount. The image forming unit as described in the above. 5. The image forming unit according to claim 1, wherein the second unit is configured to be detachable from a housing to which the first unit is fixed. 6. The image forming unit according to claim 1, wherein the first unit is configured to be detachable from a housing to which the second unit is fixed. 7. The image forming unit is detachable,
An image forming apparatus for forming an image on a transfer material, a mounting unit for mounting the image forming unit according to any one of claims 1 to 6, a transport unit for transporting the transfer material, An image forming apparatus comprising: