JP2003233290A - Unit positioning in image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a unit positioning means which is inexpensive and excellent in usability. <P>SOLUTION: The use of a simple elastic means makes it possible to attach and/or detach the unit with weak force and ensure strong holding force in a predetermined position where the unit is put in the main body. In the case of an elastic means which is a torsion coil spring, which attached, the unit contacts a long portion of the arm of the torsion coil spring and falls into the predetermined position in the main body after pushed over the portion. Once the unit is put in the predetermined position in the main body, the unit is held by a short portion of the arm of the torsion coil spring, with force stronger than that required to attach it. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to positioning of a unit in an image forming apparatus such as a copying machine or a printer using an electrophotographic method.

[0002]

2. Description of the Related Art In the positioning of the unit with respect to the main body of the image forming apparatus, conventionally, a coupling type and a lever type requiring a locking operation are generally known.

[0003]

However, the above-described conventional positioning of the coupling type or the lever type requires a large number of parts, which leads to an increase in cost, and a mechanism for releasing the coupling or lever is required for attaching / detaching the unit. It often became a barrier to user access (usability).

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention uses a simple elastic means to provide either the force necessary for attaching or detaching the unit to the main body of the image forming apparatus or the attachment or detachment thereof. One of the features is that the force on one side is configured to be weaker than the holding force required at the process operation position.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) FIG. 1 is a longitudinal sectional view showing a schematic configuration of a four-color full-color laser beam printer which is an electrophotographic image forming apparatus embodying the present invention.

{Outline of image forming operation of color image forming apparatus} The photosensitive drum 1 is rotated in the direction of the arrow (counterclockwise) in FIG. 1 in synchronization with the rotation of the intermediate transfer belt 5a, and the surface of the photosensitive drum 1 is rotated. While being uniformly charged by the charging device 2, the exposure unit 3 irradiates a yellow image with light to form a yellow electrostatic latent image on the photosensitive drum 1. Simultaneously with the formation of the electrostatic latent image, the developing device 4 is driven to position the yellow developing device 4Y at the developing position, and the yellow toner is attached to the electrostatic latent image on the photosensitive drum 1 so that the yellow toner adheres to the photosensitive drum 1. By applying a voltage having the same polarity as the charging polarity and substantially the same potential, yellow toner is attached to the electrostatic latent image for development. After that, a voltage having a polarity opposite to that of the toner is applied to the pressing roller (primary transfer roller) 5j of the intermediate transfer member 5 to primarily transfer the yellow toner image on the photosensitive drum 1 onto the intermediate transfer belt 5a.

When the primary transfer of the yellow toner image is completed as described above, the next developing device is rotationally moved and positioned at the developing position facing the photosensitive drum, and the magenta, For each color of cyan and black, electrostatic latent image formation, development, and primary transfer 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 unit is also connected to the intermediate transfer belt 5
It is in a non-contact state with a.

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 (state of FIG. 1), and further in synchronization with the rotation of the intermediate transfer belt 5a. Then, the transfer material S, which has been standing by at a predetermined position near the registration roller pair 7 as the feeding means, is sent to the nip portion between the intermediate transfer belt 5a and the secondary transfer roller 11.

Immediately before the registration roller pair 7, there is a pre-registration sensor 14 which detects the leading end of the transfer material S to shut off the rotational driving force of the registration roller pair 7 and makes the transfer material S stand by at a predetermined position. It 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 collectively conveyed. I will do it.

The transfer material S secondarily transferred in this manner
Reaches the fixing device 8 via the conveyor belt unit 12,
After fixing the toner images of a plurality of colors, the sheet is conveyed along the sheet ejection guide 15 by the sheet ejection roller pair 13 and is ejected to the sheet ejection tray 10 above the color image forming apparatus A by the sheet ejection roller pair 9 to form an image. Complete the formation.

On the other hand, after the secondary transfer, the cleaning charging roller 5f is brought into pressure contact with the intermediate transfer belt 5a to give the residual toner remaining on the intermediate transfer belt an electric charge opposite to that at the time of transfer.

The residual toner to which the opposite electric charge is applied is electrostatically attached to the photosensitive drum 1 and then collected by the cleaning blade 6 for the photosensitive drum.

The collected residual toner is collected and accumulated in the waste toner box 16 as a waste toner by following a conveyance path for conveying the toner, which will be described later.

{Photosensitive Drum and Intermediate Transfer Body Integrated Process Cartridge Unit} Next, the construction of the separable photosensitive drum and intermediate transfer belt integrated process cartridge will be described in detail.

FIG. 2 is an enlarged vertical sectional view showing a schematic structure of the process cartridge portion of FIG. 1 according to the present invention (a view seen from the left side when viewed from the front of the apparatus).

FIG. 3 is a vertical sectional view of the process cartridge as seen from the opposite side (right side) from the front side of the apparatus.

FIG. 4 is a cross-sectional view of the waste toner conveying passage portion as viewed in the direction of arrow B in FIG.

2 to 4, in the process cartridge unit 5, the photosensitive drum unit 20 is arranged on the projection upper surface of the intermediate transfer belt unit 21, and the right side surface of the photosensitive drum unit 20 when viewed from the front of the apparatus. The waste toner box portion 16 is arranged integrally. Further, the belt driving roller 40 of the intermediate transfer belt unit 21 is
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 is provided, and has an integral structure.

In the photosensitive drum unit 20, the photosensitive drum 1 is rotatably held at both ends by a right bearing 206 and a left rotary shaft 202, and a coupling 24 at the right end is provided.
A predetermined rotational driving force is transmitted from the main body of the device via the (see from the front of the device).

The charging roller 2 is pressed against the photosensitive drum 1 with a predetermined force by a compression spring 26 via bearings 25 at both ends, and is driven to rotate.

At least one of the bearings 25 is made of a conductive material, and the surface of the photosensitive drum 1 is uniformly charged by applying a predetermined charging bias voltage to the charging roller 2. Incidentally, such a contact charging type charging device is disclosed in JP-A-63-149669.

Further, a cleaning blade 6 is provided at a predetermined position on the photoconductor drum 1 to remove the residual toner on the intermediate transfer belt to which the above-mentioned reverse charge has been applied.
The toner is collected on the upper surface and scraped together with the residual toner on the photosensitive drum 1.

Further, the scraped off waste toner is prevented from falling onto the intermediate transfer belt 5a by the squeeze sheet 27, and the waste toner collected at the bottom of the photosensitive drum container 29 is seen from the front of the apparatus by the rotation of the screw 28. And is conveyed to the right side (in the direction of arrow C in FIG. 4).

In FIG. 4, the waste toner is conveyed by the screw 28 to the right side surface of the photoconductor unit 20 (as viewed from the front of the apparatus), and slides down and accumulates in the waste toner container 16.

Further, the photosensitive drum unit 20 is also provided with a drum shutter 19 which opens and closes in association with the operation of attaching to and detaching from the main body of the image forming apparatus.

Next, the structure of the intermediate transfer belt unit 21 will be described.

The intermediate transfer belt 5a is stretched around an intermediate transfer body frame 45 including a handshake portion 61 by a driving roller 40 and a driven roller 41.

Both ends of the drive roller 40 are rotatably held by a right bearing 205 and a left bearing 201, and a predetermined rotational drive force is transmitted from the main body of the apparatus via a coupling 42 at the right end. .

The bearings 43 at both ends of the driven roller are provided with compression springs 44 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, and is pressed by a predetermined force by a compression spring 47 via bearings 46 at both ends. It is driven to rotate.

At least one of the bearings 46 is composed of a conductive member, and by applying a predetermined charging bias voltage to the primary transfer roller 5j, the toner on the surface of the photosensitive drum 1 is transferred onto the intermediate transfer belt 5a. Primary transfer is performed.

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

The cleaning charging roller 5f is pressed by a predetermined force by a compression spring 52 via bearings 51 at both ends and is driven to rotate.

At least one of the bearings 51 is made of a conductive member, and a voltage opposite to that at the time of transfer is applied to the cleaning charging roller 5f to charge the residual toner on the intermediate transfer belt 5a with an opposite charge. And is electrostatically adsorbed and collected on the surface of the photosensitive drum 1 by the photosensitive drum 1 and accumulated in the waste toner box 16 as described above.

Here, the frame structure of the process cartridge 5 will be described in detail.

The frame structure is roughly divided into two.

The photoconductor drum 1 and the right bearing 2 are attached to the photoconductor drum frame 29 which is integrated with the waste toner container 16.
06, a left rotary bearing 202, a charging roller 25, a cleaning blade 6, a screw 28, and a drum shutter 19 as main components, a photosensitive drum unit 20 (a portion surrounded by a thick chain double-dashed line in FIG. 4) and an intermediate transfer body. An intermediate transfer belt 5a is stretched around a frame 45 by a driving roller 40 and a driven roller 41, and a primary transfer roller 5j is provided inside the intermediate transfer belt facing the photosensitive drum 1, and a cleaning charging roller is provided as the driving roller 40. It is divided into an intermediate transfer belt unit 21 in which 5f is also arranged.

In these two units, the protrusions 71 provided at both the left and right ends of the photosensitive drum frame 29 are inserted into the positioning holes 72 provided in the intermediate transfer member frame 45, respectively, while the photosensitive drum frame 29 is also provided. Snap-fit type hook claw 73 provided in the center of the width direction of the
Are fitted and connected to the lock holes 74 of the intermediate transfer member frame 45.

Here, the positioning hole 72 and the lock hole 74 provided in the intermediate transfer member frame 45 are made larger than the protrusion 71 and the hook claw 73 provided in the photosensitive member frame 29 by a predetermined amount. Thus, a predetermined amount of relative position movement is possible between the photoconductor unit 20 and the intermediate transfer belt unit 21.

Further, the positioning hole 72 is provided with a taper portion 72a for easy attachment and detachment.

In FIG. 3, the hook claw 73 of the photoconductor unit 20 is pushed in the direction of arrow D to release it from the lock hole 74 of the intermediate transfer belt unit 21, and the photoconductor unit 20 is shown by arrow E as shown in FIG. By rotating in the direction, it can be divided into a photoconductor unit and an intermediate transfer body unit as shown in FIGS.

At the time of connection, conversely, the protrusion 71 of the photoconductor unit 20 is inserted into the positioning hole 72 of the intermediate transfer belt unit 21 and rotated in the direction opposite to the arrow E in FIG. 5 to lock the hook claw 73. By pushing into the hole 74, the two units are connected.

{Positioning Method of Cartridge to Apparatus Main Body} Referring to FIG. 8, a method of attaching / detaching the process cartridge 5 to / from the color image forming apparatus main body A and fixing it to a predetermined position will be described.

When the upper lid 60 of the main body A of the color image forming apparatus is opened, the supporting portions 102, 1 for supporting the photosensitive drum bearings
The rotational driving force transmission coupling to the photoconductor drum 1 provided in 06, and the rotational driving force to the intermediate transfer belt driving roller provided in the supporting portions 201 and 205 for supporting the bearing portion of the intermediate transfer belt driving shaft. The transmission coupling slides in the axial direction and is retracted (disconnected state).

With respect to the retracting and connecting mechanism of the coupling, there is a method as disclosed in Japanese Patent Laid-Open No. 11-109836, etc., and it is omitted in this embodiment.

A photoconductor drum guide rail 100 and an intermediate transfer body guide rail 101 are provided on both sides of the apparatus main body with a step γ.

The photosensitive drum right side bearing 206 and the left rotary shaft 202 of the process cartridge 5 are guided to the photosensitive drum guide line 100, the right side bearing 205 and the left side bearing 201 of the intermediate transfer belt driving roller, and the protrusions provided on the left and right side covers. The parts 203 and 204 are placed on the intermediate transfer member guide rail 101, respectively, and are slid and inserted.

Finally, the right side bearing 20 of the photosensitive drum
6. The left rotation shaft 202 falls into the supporting portion 102 that supports the photosensitive drum bearing, and the right bearing 205 and the left bearing 201 of the intermediate transfer belt driving roller fall into the supporting portion 103 that supports the bearing portion of the intermediate transfer belt driving shaft. The projections 203 and 204 provided on the left and right side covers respectively fall into the positioning groove 104 and are pressed and fixed to the positioning of the apparatus main body frame by torsion coil springs as shown in FIG.

{Torsion coil spring (holding elastic means)} As shown in FIGS. 9-a, 9-b and 9-c, when the cartridge is mounted, the bearing portions 102, 106 of the cartridge are mounted.
Since the arm length of the torsion coil spring 26 hits at the L portion, it is possible to push the cartridge into the deciding position with a weak force, and once fixed in the deciding position, the arm length of the torsion coil spring 26 is changed. Therefore, the holding force becomes stronger than that when the cartridge is mounted.

(Embodiment 2) The opposing fixed walls pressed by the torsion coil spring of Embodiment 1 are shown in FIGS.
As shown in FIG. 10B and FIG. 10C, the roller 110 is formed, and the detachability of the cartridge is improved.

[0053]

According to the present invention, the force required for attaching and detaching the unit to and from the image forming apparatus main body is weaker than the holding force after attachment, so that the function is satisfied and the detachability is further improved, and the lock mechanism and the coupling mechanism are provided. Since it does not exist, user accessibility is high. Further, since the photoconductor drum, the intermediate transfer member driving roller, and the intermediate transfer member driven roller are held only by the two left and right torsion coil spring parts, the cost merit is very high.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an electrophotographic color image forming apparatus embodying the present invention.

FIG. 2 is a vertical sectional view of a process cartridge embodying the present invention.

FIG. 3 is a vertical cross-sectional view of a process cartridge embodying the present invention viewed from the opposite direction.

FIG. 4 is a cross-sectional view as seen from the direction of arrow B in FIG.

FIG. 5 is a diagram showing a process of dividing a photoconductor unit and an intermediate transfer belt unit.

FIG. 6 is an intermediate transfer belt unit.

FIG. 7 is a photoconductor unit.

FIG. 8 is a view showing how the cartridge is attached to and detached from the apparatus main body.

FIG. 9 is a diagram showing a torsion coil spring.

FIG. 10 is a diagram showing a torsion coil spring.

[Explanation of symbols]

1 Photosensitive Drum 2 Photosensitive Drum Charging Roller 3 Exposure Means 4 Developing Device (Development Rotary) 5 Process Cartridge 5a Intermediate Transfer Belt 5f Cleaning Charging Roller 5j Primary Transfer Roller 16 Waste Toner Box 18 Paper Feed Pickup Roller 20 Photosensitive Unit 21 Intermediate transfer belt unit 25 Intermediate transfer belt driven roller positioning torsion coil spring 26 Photosensitive member positioning torsion coil spring 27 Intermediate transfer belt drive roller positioning torsion coil spring 28 Waste toner conveying screw 71 Projection 72 Positioning hole 73 Hook claw 74 Lock hole

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H035 CA07 CB03 CD02 CD05 CD07                       CD11 CD14 CG03                 2H071 BA04 BA13 BA16 BA29 BA42                       CA02 CA05 DA09 DA15                 2H200 FA12 GA23 GA34 GA47 GB12                       GB25 HA02 HB12 JA02 JC04                       LA03 LA06 LA12 LA17 LA27                       LA38

Claims (4)

[Claims] 1. A unit composed of at least one of an image carrier, an intermediate transfer member, and a toner CRG is attachable to and detachable from the image forming apparatus main body, and the unit is elastic in the image forming apparatus main body. It is pressed against a fixed wall or a rotating roller inside the main body of the image forming apparatus and positioned and held by the means. The elastic means is configured such that a force required when mounting or removing the unit from a determined position (process operation position) is lower than a holding force at the determined position. To do. 2. An image carrier (photoreceptor) unit, an intermediate transfer member unit, or both of the positions to be fixed to the image forming apparatus main body, and the image carrier and the intermediate transfer member driving roller shaft are coaxial. The image forming apparatus according to item 1. 3. The image forming apparatus according to claim 2, wherein the drive transmission method from the main body of either or both of the image bearing member (photoreceptor) unit and the intermediate transfer member unit is coupling. 4. The image carrier (photoreceptor) and the intermediate transfer member are integrated into a unit, and the determined position with respect to the main body of the image forming apparatus and the drive roller shafts of the image carrier (photoreceptor) and the intermediate transfer member are coaxial. 2. The image forming apparatus according to claim 1, wherein the drive transmission method from the image forming apparatus main body is a coupling, and the holding means of the unit is a torsion coil spring.