JPH09138590A - Attaching structure of transfer roller in image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the control of members by reducing the number of the members required for attaching a transfer roller and to reduce the cost by reducing assembly man-hours, in the attaching structure of the transfer roller in an image forming device. SOLUTION: The device is provided with the transfer roller 15 disposed to face the transfer area of a photoreceptor drum 21, transfer roller supports 80 for supporting the transfer roller 15 and a carrying guide 14 which is arranged so that one end faces the transfer area of the photoreceptor drum 21, to form a carrying path for a transfer paper. The transfer roller 15 is provided with a rotary shaft 151 projected from both ends in an axial direction and the transfer roller supports 80 are provided with bearing grooves 81 opened at the top ends and pivotally support, the rotary shaft of the transfer roller 15 in the bearing grooves 81. The carrying guide 14 is provided with a projecting member 141 projected to the side of the transfer roller 15 and the projecting member 141 is arranged in a position for preventing the fall-off of the rotary shaft out of the openings of the bearing grooves 81.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer roller mounting structure in an image forming apparatus such as a facsimile or an electronic copying machine.

[0002]

2. Description of the Related Art An image forming apparatus such as a facsimile or an electronic copying machine forms a latent electrostatic image on its surface, develops the latent electrostatic image into a toner image, and transfers the toner image onto a transfer paper. A body drum and a transfer roller for applying a voltage having a polarity opposite to the polarity of the electrostatic latent image from the back surface side of the transfer paper when the toner image is transferred onto the transfer paper are configured. In such an image forming apparatus, the transfer roller is attached with a structure as shown in FIG. That is, the transfer roller 100 has a pair of rotating shafts 101 projecting from both ends in the axial direction thereof, and is arranged so as to face the transfer area of the photosensitive drum 110, and the pair of rotating shafts 101 supports a pair of transfer rollers. It is pivotally attached to the body 120. A bearing groove 121, which opens at the upper end, is formed in the transfer roller support body 120 in the vertical direction.
21, a bearing member 122 is arranged on the upper portion, and an elastic member 123 made of a spring or the like for imparting an urging force to the upper portion of the bearing member 122 is arranged on the lower portion. The rotating shaft 10
1 is axially supported by the bearing groove 121 via the bearing member 122, and the rotation shaft 101 of the transfer roller 100 is not separated from the bearing groove 121 of the transfer roller support 120 at the upper end of the transfer roller support 120. The retaining member 124 is screwed onto.

[0003]

However, in the above-described conventional mounting structure of the transfer roller 100, the transfer roller 1 is provided by the retaining member 124 which is independent of other members.
Since the rotating shaft 101 of No. 00 does not separate from the bearing groove 121 of the transfer roller support 120, there is a problem that the number of members increases and the management of the members becomes complicated.
In addition, there is a problem in that the work of attaching the retaining member 124 is required and the assembling cost increases, which hinders the cost reduction.

Therefore, according to the present invention, the number of members required for mounting the transfer roller can be reduced to simplify the management of the members, and the number of assembling steps can be reduced to reduce the cost. An object is to provide a mounting structure for a transfer roller.

[0005]

In order to achieve such an object, a transfer roller mounting structure in an image forming apparatus according to a first aspect of the present invention is a transfer roller disposed so as to face a transfer area of a photosensitive drum. An image forming apparatus including a roller, a transfer roller supporter that supports the transfer roller, and a conveyance guide that forms a conveyance path for the transfer paper, one end of which faces the transfer area of the photosensitive drum. The transfer roller has a rotary shaft protruding from both ends in the axial direction, the transfer roller support has a bearing groove opening at the upper end, and the rotary shaft of the transfer roller is formed in the bearing groove. The transport guide has a projecting member that is axially supported and projects toward the transfer roller, and the projecting member is arranged at a position that prevents the rotary shaft from coming out of the opening of the bearing groove. It is characterized.

In the mounting structure of the transfer roller in the image forming apparatus according to the first aspect of the present invention, the rotation shaft of the transfer roller is prevented from coming out of the opening of the bearing groove of the transfer roller support by the protruding member formed on the conveyance guide. To be done.

The transfer roller mounting structure in the image forming apparatus according to a second aspect of the present invention is the one according to the first aspect, wherein the transport guide having the projecting member feeds the transfer sheet to the transfer area of the photosensitive drum. It is characterized by being

In the transfer roller mounting structure in the image forming apparatus according to the second aspect of the present invention, the rotating shaft of the transfer roller is rotated by the protruding member formed on the conveyance guide for feeding the transfer sheet to the transfer area of the photosensitive drum. The transfer roller support is prevented from coming out of the opening of the bearing groove.

Further, the mounting structure of the transfer roller in the image forming apparatus according to a third aspect is the one according to the first or second aspect, wherein the bearing groove is formed in a vertical direction, and the first groove is formed above the bearing groove. A bearing member is provided, and an elastic member that applies a biasing force to the upper side is provided at the lower portion of the first bearing member, and the rotation shaft of the transfer roller is the first member.
It is characterized in that it is axially supported in the bearing groove via the bearing member.

In the mounting structure of the transfer roller in the image forming apparatus according to the third aspect, the transfer roller surely comes into contact with the photosensitive drum by the urging force of the elastic member.

Further, the mounting structure of the transfer roller in the image forming apparatus according to claim 4 is the structure according to claim 3, wherein the first bearing member has an outer diameter larger than the outer diameter of the transfer roller. Second with circular body coaxially
Bearing member is fitted, the rotary shaft of the transfer roller is axially supported in the bearing groove through the second bearing member and the first bearing member in order, and the circular body is an end of the photosensitive drum. It is characterized in that it is in contact with the edge.

In the mounting structure of the transfer roller in the image forming apparatus according to the fourth aspect of the present invention, the circular body of the second bearing member abuts on the photosensitive drum, so that a gap is formed between the photosensitive drum and the transfer roller. Form.

[0013]

FIG. 6 is a front view showing a schematic configuration of a facsimile of an embodiment to which a mounting structure of a transfer roller in an image forming apparatus of the present invention is applied.

The facsimile is provided with a transfer sheet feeding section 10 arranged at a lower portion, a process unit 20 provided above the transfer sheet feeding section 10, and a process unit 20 provided above the process unit 20. The optical unit 30, the document placing table 40 and the document reading unit 50 arranged above the optical unit 30, the transfer paper discharge tray 60 extending to the left outside of the transfer paper feeding unit 10, and the document reading. The document discharge tray 70 is provided on the left outer side of the section 50. Less than,
Main constituent members will be described.

The transfer paper feeding unit 10 includes a paper feed cassette 11 arranged at the bottom, a paper conveyance path 12 for guiding the transfer paper arranged at the upper right of the paper feed cassette 11, and a pair of registration rollers arranged downstream thereof. 13, a transfer guide (pre-transfer guide) 14, a transfer roller 15, a transfer guide (post-transfer guide) 16, a fixing unit 17, and a discharge roller pair 1 in that order to the left.
8 is provided.

The paper feed cassette 11 stores transfer paper, and a paper feed roller 19 for taking out the transfer paper and feeding it to the paper transport path 12 side is arranged above the right end portion. The conveyance guide 14 feeds the transfer sheet fed via the pair of registration rollers 13 to the transfer area of the photosensitive drum 21 described later. The transfer roller 15 is arranged such that both peripheral surfaces thereof are close to each other at a position facing a transfer area of the photosensitive drum 21 described later. The transport guide 16 discharges the transfer paper on which the toner image has been transferred in the transfer area of the photosensitive drum 21, which will be described later, to the fixing unit 17 side. The fixing unit 17 fixes the transfer paper on which the toner image is transferred.

The process unit 20 includes the photosensitive drum 2
1, a charger 22 is provided on the upper side along the peripheral surface of the photosensitive drum 21, a developing unit 23 is provided on the right side of the charger 22, and a cleaning unit 24 is provided on the left side of the charger 22. The photoconductor drum 21 is driven to rotate in the direction indicated by the arrow, and an electrostatic latent image is formed at a position facing the charger 22.
The electrostatic latent image is developed into a toner image at a position facing 3 and the toner image is transferred to the transfer paper at a position facing the transfer roller 15. Further, the toner remaining on the surface is removed at the position facing the cleaning unit 24.

The optical unit 30 exposes an image on the photosensitive drum 21, and is provided with a light emitting portion including a laser light source, a polygon mirror, and the like, a reflection mirror for reflecting the laser light toward the photosensitive drum 21, and the like. There is.

The document reading section 50 includes a pair of conveying rollers and a CCD.
And the like. The original placed on the original placing table 40 is conveyed to the downstream side by the conveying roller pair, and the original image is read by the CCD and stored in a memory (not shown) as image data. The document from which the image is read is discharged to the document discharge tray 70.

The facsimile configured as described above is
It works as follows. That is, in the facsimile reception mode, the image signal received through the telephone line (not shown) is stored in the memory (not shown). In the facsimile transmission mode and the copy mode, the original placed on the original placing table 40 is fed to the original reading unit 50, the image of the original is read by the original reading unit 50, and the read image signal is not shown. Stored in memory. The document from which the image is read is discharged to the document discharge tray 70.

In the facsimile transmission mode, the image signal stored in the memory is transmitted to the facsimile of the other party through the telephone line. In the copy mode or the facsimile reception mode, the image stored in the memory is transferred onto the transfer paper. That is, the photoconductor drum 21 is charged by the charger 22, and a laser beam corresponding to the image signal stored in the memory is emitted toward the photoconductor drum 21 to expose the electrostatic latent image forming area, and the electrostatic latent image forming area is exposed. A latent image is formed. Then, the charged toner supplied from the developing unit 23 to the photosensitive drum 21 adheres to the electrostatic latent image to develop the electrostatic latent image.

On the other hand, the transfer paper stored in the paper feed cassette 11 is fed by the paper feed roller 19, and in synchronism with the development, the registration roller pair 13 moves the photosensitive drum 21 and the transfer roller 15 via the conveyance guide 14. It is transported to the gap.
The transfer paper is separated from the photosensitive drum 21 after the toner image on the photosensitive drum 21 is transferred by the transfer roller 15 to which a voltage having a polarity opposite to the polarity of the electrostatic latent image is applied, and the toner image is fixed by the fixing unit 17. Is fixed and is discharged onto the discharge tray 60 by the discharge roller pair 18.

Next, the mounting structure of the transfer roller 15 in the above facsimile will be described with reference to FIGS.

FIG. 1 is a perspective view of a transfer roller mounting structure, FIG. 2 is an exploded perspective view of a main part of the transfer roller mounting structure, and FIG. 3 is a plan view of the transfer roller mounting structure.

In these figures, the transfer roller 15 arranged at a position facing the transfer area of the photosensitive drum 21 is
It is attached to the pair of transfer roller supports 80. The pair of transfer roller support members 80 each have a vertically formed bearing groove 81 that opens at the upper end, and a first bearing member 82 is disposed above each bearing groove 81.
An elastic member 83, which is a spring that applies a biasing force to the upper side of the first bearing member 82, is disposed in the lower portion.

The bearing groove 81 has retaining walls 811 and 812 projecting from both sides of the bearing groove 81 at the upper end and the central portion thereof.
Is formed, and the locking projections 8 are formed near the bottom and the center.
13, 814 are formed. First bearing member 82
Has a bearing portion 821 at the upper end and a bulge portion 822 at the lower end and is formed in an elongated shape. The elastic member 83 is disposed below the bearing groove 81, so that the bearing portion 821 is at the upper end. The bulging portion 822 is arranged in the bearing groove 81 so as to correspond to the position of the retaining wall 811 of the central portion and the position of the retaining wall 812 of the central portion. As a result, the first bearing member 82 is prevented from coming off the retaining wall 8
It moves up and down within the range in which 11, 812 are formed, but does not come out from the side surface of the bearing groove 81 to the outside.

The elastic member 83 has locking projections 813, 81.
4 is fixed in the bearing groove 81, and the first bearing member 82
Is pressed from above, the first bearing member 82
It is designed to give an urging force to push it back to the upper side.

A through hole 821a is formed in the bearing portion 821 of the first bearing member 82, and a cylindrical second bearing member 85 is fitted in the through hole 821a. A circular body 851 having an outer diameter larger than the outer diameter of the transfer roller 15 is coaxially formed on the second bearing member 85, and the circular body 851 is provided on the side facing the first bearing member 82. Is formed with a stepped portion 852 that regulates the distance between the first bearing member 82 and the circular body 851. Note that this step 852
Is not mandatory.

The outer peripheral surface of the circular body 851 contacts the outer peripheral surface of the transfer roller 15 and the outer peripheral surface of the photoconductor drum 21 by abutting the outer peripheral surfaces thereof on the areas where both ends of the photoconductor drum 21 in the axial direction are not formed. A small gap (for example, 0.2 to 2.0 mm, which is slightly larger than the thickness of the transfer paper)
To form That is, when the transfer paper comes into contact with the photosensitive drum 21 with a large contact pressure, a so-called void phenomenon (a phenomenon in which toner is not present in a part of an image such as a transferred character) or an image dust phenomenon (transferred character) is generated. The phenomenon that toner is present in the vicinity of the image) easily occurs, but the formation of the above-mentioned gap prevents the occurrence thereof.

The transfer roller 15 has a rotary shaft 151 protruding from both ends in the axial direction, and is fitted to the transfer roller support 80 by fitting the rotary shaft 151 into the second bearing member 85. . That is, the transfer roller 15 is attached to the transfer roller support 80 by the rotation shaft 151 of which is axially supported by the bearing groove 81 through the second bearing member 85 and the first bearing member 82 in order, and
When the circular body 851 of the bearing member 85 comes into contact with the photosensitive drum 21, the circular member 851 is pushed downward against the elastic force of the elastic member 83. As a result, the first bearing member 82 is biased to the upper side, and the contact between the circular body 851 and the photosensitive drum 21 is kept good. It should be noted that the transfer roller 15 is driven by a drive motor to rotate one of the rotary shafts 151.
It rotates in synchronism with the feeding of the transfer paper via a gear 86 attached to the tip of the.

The transport guide 14 for feeding the transfer paper to the transfer area of the photosensitive drum 21 is fixed at a predetermined position in the facsimile, and is formed at both ends in the width direction thereof so as to project to the transfer roller 15 side. It has a pair of projecting members 141. The pair of projecting members 141 are disposed so as to be located above the rotary shafts 151 at both ends of the transfer roller 15.
The rotation shaft 151 of the transfer roller 15 is prevented from slipping out of the bearing groove 81 together with the first and second bearing members 82 and 85 when the photosensitive drum 21 is not present in a position close to the transfer roller 15. .

That is, the photosensitive drum 21 is located near the transfer roller 15 when the facsimile is being assembled or when the upper cover of the facsimile is opened and the process unit 20 is moved upward. If not, when a force is applied to the transfer roller 15 in the upward direction, the rotary shaft 151 comes out of the opening of the bearing groove 81 together with the first and second bearing members 82 and 85. Therefore, when the photoconductor drum 21 does not exist in the vicinity of the transfer roller 15, as shown in FIG.
The rotary shaft 151 of the transfer roller 15 is prevented from coming out of the opening of the bearing groove 81 by abutting on the upper peripheral surface of the bearing member 85.

When the photoconductor drum 21 is disposed at a predetermined position near the transfer roller 15, the photoconductor drum 21 moves to the second position.
Since it abuts on the circular body 851 of the bearing member 85, the transfer roller 15 is slightly pushed down to the lower side against the elastic force of the elastic member 83, as shown in FIG. Therefore, the protruding member 141 is in a state of floating above the peripheral surface of the second bearing member 85 and does not apply an extra load to the transfer roller 15 when the transfer roller 15 rotates, so that the transfer roller 15 can be smoothly rotated. Guaranteed. When the photoconductor drum 21 moves away from the transfer roller 15 again due to the upper cover of the facsimile being opened, the transfer roller 15 is pushed upward by the elastic member 83, and the second bearing member 85 is moved.
The upper part of the peripheral surface of the bearing contacts the protruding member 141, and the rotation shaft 151 is prevented from coming out of the opening of the bearing groove 81.

The mounting structure of the transfer roller in the image forming apparatus of the present invention is configured as described above, but various modifications as described below are possible.

That is, the rotary shaft 151 of the transfer roller 15
The protruding member 141 that prevents the toner from coming out of the opening of the bearing groove 81 is arranged so as to be located above the rotary shaft 151 of the transfer roller 15 in the above-described embodiment, but the end edge of the transfer roller 15 itself. You may arrange | position so that it may be located in the upper part of a part etc. In this case, when the photosensitive drum 21 does not exist in the position close to the transfer roller 15, the protruding member 141 contacts the upper part of the peripheral surface of the transfer roller 15 and the rotary shaft 151 comes out of the opening of the bearing groove 81. Prevent.

Further, although the projecting member 141 is formed on the transport guide 14 for feeding the transfer sheet to the transfer area of the photosensitive drum 21 in the above-mentioned embodiment, the projecting member 14 is formed.
Instead of 1, the same projecting member may be formed on the transport guide 16 that discharges the transfer paper on which the toner image is transferred in the transfer area of the photoconductor drum 21 to the fixing unit 17 side.
Even in this case, similarly to the case of the above-described embodiment, the rotation shaft 151 of the transfer roller 15 can be prevented from coming out of the opening of the bearing groove 81. In short, both of the transport guides 14 and 16 are arranged so that one ends thereof face the transfer area of the photosensitive drum 21, and both form a transfer paper transport path. Therefore, a projecting member projecting to the transfer roller side may be formed in a transport guide that forms a transport path for the transfer paper, one end of which faces the transfer area of the photosensitive drum 21. In addition, the transport guide 16 may be composed of a transport belt, and in this case, the protruding member is always formed on the transport guide 14 as in the above-described embodiment.

Further, in the above embodiment, the circular body 851 formed on the second bearing member 85 is brought into contact with the photosensitive drum 21, but the circular body 851 is removed and the transfer roller 15 and the photosensitive drum 21 are exposed. You may make it contact | abut directly with the body drum 21. In this case, the second bearing member 85 becomes unnecessary. Further, the first bearing member 82 may be removed so that the rotary shaft 151 of the transfer roller 15 is directly supported by the bearing groove 81 of the transfer roller support 80, and the elastic member 83 is removed. You can also do so. The circular body 851 is directly attached to the transfer roller 15
When it is formed on the rotary shaft 151 of
The second bearing member 85 can be eliminated even when the above is required.

[0038]

As described above, according to the first to fourth aspects of the invention, the rotary shafts projecting from both axial ends of the transfer roller are axially supported by the bearing grooves of the transfer roller support member and are formed in the conveyance guide. Since the projecting member prevents the rotary shaft from slipping out of the opening of the bearing groove, the number of independent members required for mounting the transfer roller is reduced, and as a result, the management of the member can be simplified. Further, since the rotary shaft is prevented from coming out of the opening of the bearing groove only by attaching the conveyance guide, the number of assembling steps can be reduced, and as a result, the cost can be reduced.

According to the second aspect of the present invention, the protruding member for preventing the rotary shaft of the transfer roller from coming out of the opening of the bearing groove is formed on the conveyance guide for feeding the transfer paper to the transfer area of the photosensitive drum. Therefore, the rotation shaft of the transfer roller can be reliably prevented from coming out of the opening of the bearing groove.

According to the third aspect of the present invention, the first bearing member is disposed above the bearing groove, and the elastic member for imparting a biasing force to the upper side of the first bearing member is disposed below the bearing groove. Since the rotary shaft of the transfer roller is axially supported by the bearing groove via the first bearing member, the transfer roller can be reliably brought into contact with the photosensitive drum by the biasing force of the elastic member.

According to the invention of claim 4, a second bearing member having a circular body coaxially with a circular body having an outer diameter larger than the outer diameter of the transfer roller is fitted to the first bearing member, The rotating shaft of the transfer roller is axially supported in the bearing groove through the second bearing member and the first bearing member in this order, and the circular body of the second bearing member is brought into contact with the edge portion of the photosensitive drum. Therefore, a gap is formed between the photoconductor drum and the transfer roller, so that it is possible to prevent the occurrence of the hollow image phenomenon and the image dust phenomenon when the toner image is transferred onto the transfer paper.

[Brief description of the drawings]

FIG. 1 is a perspective view of a transfer roller mounting structure in an image forming apparatus of the present invention.

FIG. 2 is an exploded perspective view of a main part of the transfer roller mounting structure shown in FIG.

FIG. 3 is a plan view of a mounting structure of the transfer roller shown in FIG.

4A and 4B are diagrams illustrating a contact state between a protruding member formed on a conveyance guide and a second bearing member in the transfer roller mounting structure shown in FIG.

5A and 5B are diagrams illustrating a contact state between a protruding member formed on a conveyance guide and a second bearing member in the transfer roller mounting structure shown in FIG.

FIG. 6 is a front view showing a schematic configuration of a facsimile to which the transfer roller mounting structure in the image forming apparatus of the present invention is applied.

FIG. 7 is a perspective view of a mounting structure of a transfer roller in a conventional image forming apparatus.

[Explanation of symbols]

 14 Transport Guide 15 Transfer Roller 21 Photoreceptor Drum 80 Transfer Roller Support 81 Bearing Groove 82 First Bearing Member 83 Elastic Member 85 Second Bearing Member 141 Projecting Member 851 Circular Body

Claims (4)

[Claims] 1. A transfer roller arranged to face the transfer area of the photoconductor drum, a transfer roller support for supporting the transfer roller, and one end of the transfer roller support body facing the transfer area of the photoconductor drum. And a transfer guide for forming a transfer path for the transferred transfer sheet, wherein the transfer roller has a rotating shaft projecting from both ends in the axial direction. The support has a bearing groove that is open at the upper end, the rotation shaft of the transfer roller is rotatably supported in the bearing groove, and the conveyance guide has a protruding member that protrudes toward the transfer roller. A structure for mounting a transfer roller in an image forming apparatus, wherein the rotary shaft is arranged at a position that prevents the rotary shaft from coming out of the opening of the bearing groove. 2. A transfer roller mounting structure for an image forming apparatus according to claim 1, wherein the conveyance guide having the projecting member is for feeding a transfer sheet to a transfer area of the photosensitive drum. . 3. The bearing groove is formed in a vertical direction, a first bearing member is disposed on an upper portion of the bearing groove, and an urging force to the upper side is applied to the lower portion of the first bearing member. An elastic member is provided, and the rotation axis of the transfer roller is the first
3. The transfer roller mounting structure for an image forming apparatus according to claim 1, wherein said transfer roller is axially supported by said bearing groove via said bearing member. 4. A second bearing member coaxially equipped with a circular body having an outer diameter larger than the outer diameter of the transfer roller is fitted to the first bearing member, and a rotary shaft of the transfer roller. Is axially supported in the bearing groove through the second bearing member and the first bearing member in this order, and the circular body is in contact with the edge portion of the photosensitive drum. Item 3
A structure for mounting a transfer roller in the image forming apparatus described in claim 1.