JP2001134164A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dissolve a problem that a transfer roll is deviated in position from a photoreceptor drum when a carrier passage is opened/closed in the case of maintenance in an image forming device of a copying machine, etc. SOLUTION: In a copying machine 1 including the image forming device 8, an image forming unit 40 including the photoreceptor drum 41 is supported so as to be attachable/detachable and a transfer unit 46 including the transfer roller is supported so as to be rotatable in the base member 32 of a housing 30. A positioning member 61 for positioning the transfer roller 47 is disposed in the casing 35 of the image forming unit 40. A guide member 56 for guiding a sheet of paper to a part between the transfer roller 47 and the drum 41 is attached to the casing 35 as a guide unit 60 which is integrated with the positioning member 61. The transfer roller 47 and the guide member 56 are stably positioned with respect to the photoreceptor drum 41 regardless of the attachment/detachment of the unit 40 or the displacement of the unit 46. Then an excellent image is stably obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrostatic copying machine, an electrostatic latent image is formed on a photosensitive drum, the electrostatic latent image is visualized with toner, and the visualized toner image is transferred. Transfer to paper as body. For this purpose, there is a printer in which a transfer roller is provided facing the peripheral surface of the photosensitive drum. The paper passes between the transfer roller and the peripheral surfaces of the photosensitive drums, and during that time, a predetermined voltage is applied to the transfer roller to transfer the toner image formed on the photosensitive drum to the paper.

The transfer roller is positioned at a predetermined position relative to the photosensitive drum in order to stably obtain a clear image. On the other hand, the transfer roller can be displaced with respect to the photosensitive drum for maintenance such as a jam clearance. For example, the photoconductor drum is rotatably supported while being positioned with respect to the base member, and the transfer roller is rotatable while being positioned with respect to a conveyance base forming a conveyance path around the photoconductor drum. Supported. The transport base and the base member are connected to each other.
Further, the transport base is rotatably supported by the base member, and the transport path can be opened and closed by rotating the transport base. When the transport path is closed, the transfer roller can be disposed at the above-described predetermined position with respect to the photosensitive drum via the base member, the transport base, and the like, so that an image can be formed. Further, when the transport path is opened, the transfer roller comes to be spaced apart from the photosensitive drum.

[0004]

However, when the transport path is opened and closed, the transfer roller may not be positioned at the above-described predetermined position relative to the photosensitive drum when the transport path is closed. As a result, it is assumed that a variation occurs in the image. Therefore, an object of the present invention is to solve the above-described technical problem, and to position the transfer roller with respect to the photosensitive drum without displacement when the transport path is opened and closed to return to an image forming state. It is an object of the present invention to provide an image forming apparatus capable of performing the above.

[0005]

According to the first aspect of the present invention, there is provided an image forming apparatus, comprising: a photosensitive drum which forms a toner image on a surface while rotating; and a photosensitive drum which rotates while facing the photosensitive drum. A transfer roller for transferring the toner image on the surface of the body drum to the sheet, a casing for supporting both end portions of the photosensitive drum in the axial direction, and holding the transfer roller while forming a sheet conveyance path between the casing and the casing. A transfer base that closes a transfer path so that an image can be formed and a transfer roller approaches and opposes the photosensitive drum; and a transfer roller that opens the transfer path and sets a transfer roller relative to the photosensitive drum. In the image forming apparatus that is displaceably connected to the casing at a position where the transfer roller is separated from the photosensitive drum, when the transfer path is closed and the transfer base is arranged, Positioning members for positioning the vicinity of both ends direction, to provide an image forming apparatus, characterized in that provided in the casing.

According to the present invention, since the positioning member is attached to the casing, the transfer roller can be stably positioned with respect to the photosensitive drum when the transfer path is opened and closed without closing the photosensitive drum. As a result, the paper can be stably conveyed, and an image with no variation can be obtained. According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the casing is provided with a guide member for guiding a sheet between the transfer roller and the photosensitive drum. The image forming apparatus is characterized in that the unit and the positioning member form an integrated unit, and the unit is positioned at a predetermined position with respect to the photosensitive drum.

According to the present invention, when the transport path is opened and closed, the guide member can also be positioned stably with respect to the photosensitive drum and the transfer roller, so that a more uniform image can be obtained. Can be. In particular, since the positioning member and the guide member constitute a unit, positioning with respect to the photosensitive drum is easy.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings, taking a copying machine as an example.
FIG. 1 is a front view showing a schematic configuration of a copying machine according to the present embodiment. The copying machine 1 includes an apparatus main body 2 in which an image forming apparatus 8 and the like are accommodated, and a document feeder 6 provided on an upper surface of the apparatus main body 2. The apparatus main body 2 includes an upper part 3 and a lower part 4.
And a paper discharge unit 5 partitioned between the upper part 3 and the lower part 4 to discharge the paper. The paper discharge unit 5 is exposed through a window 7 defined between the upper part 3 and the lower part 4.

A reading section 20 is provided on the upper part 3 of the apparatus main body 2. A document placing plate 21 is provided on the upper surface of the upper part 3, and the document feeder 6 is attached to the upper surface so as to be rotatable and openable. The document feeder 6 automatically feeds out the document placed on the upper surface thereof one sheet at a time, and sends it out to the upper surface via the document placing plate 21. The reading unit 20 exposes a document passing over the transparent document placing plate 21 by the document feeding unit 6,
Alternatively, the original placed on the original placing plate 21 is exposed and scanned, and the reflected light from the original is guided to the light receiving element 24 by an optical system such as a mirror 22 and a lens 23, and the reflected light is converted into an electric signal by the light receiving element 24. Convert to A signal from the reading unit 20 is subjected to predetermined processing by a signal processing unit (not shown) and output.

The lower part 4 of the apparatus main body 2 is
0 has the following components. That is, a light irradiation unit (LSU) 9 that obtains a predetermined light beam by scanning a laser beam from a semiconductor laser or the like oscillated by a polygon mirror or the like in accordance with a signal from a signal processing unit.
A photosensitive drum 41 for forming a latent image according to the light from the light irradiation unit 9, a charging charger 42 for charging the photosensitive drum 41, and a developing roller for charging the electrostatic latent image formed on the photosensitive drum 41 to a developing roller An image forming unit 40 including a developing device 43 for developing an image with toner supplied by using the toner 44 and a cleaner 45 for cleaning the surface of the photosensitive drum 41 after the transfer of the toner image. A transfer unit 4 that includes a transfer roller 47 provided opposite to the photosensitive drum 41 and transfers the sheet in a predetermined direction in order to transfer the image visualized by the image forming unit 40 to the sheet.
6. A fixing section 48 for heating and fixing the toner image transferred to the sheet; The paper is fed from a paper feed cassette 51 by a paper feed roller 52, and is passed from the front part 11 including the pair of registration rollers 53 through the image forming unit 40 and the fixing unit 48.
A paper transport unit 10 that discharges the paper to the paper discharge unit 5 by a rear part 12 including a transport roller 54; A transport path 13 that is partitioned inside the paper transport unit 10, between the image forming unit 40 and the transfer unit 46, inside the fixing unit 48, and the like, and through which paper is passed. These components are provided in the housing 30. The image forming unit 40 and the transfer unit 46 constitute an image forming apparatus 8 that forms a toner image on a sheet.

The photosensitive drum 41 has a cylindrical shape, and is arranged such that the central axis thereof extends forward and backward. The photoreceptor drum 41 forms a toner image on the surface while rotating, for example, clockwise in FIG. Further, the above-described transfer roller 47 is disposed so as to approach and face the peripheral surface of the photosensitive drum 41. The transfer roller 47 is applied with a predetermined voltage, and charges the sheet when the conveyed sheet contacts the transfer roller 47. The transfer roller 47 transfers the charged toner image adhering to the photoconductive drum to the charged paper by electrostatic attraction while passing the paper between the photoconductive drum 41 while rotating.

In the transport path 13, a portion near the photosensitive drum 41 and the transfer roller 47 guides the transported paper to a transfer area formed between the transfer roller 47 and the photosensitive drum 41. Guide members 56 and 57
Is provided. The pair of guide members 56 and 57 are plate-shaped members that are arranged on the upstream side of the photosensitive drum 41 in the sheet transport direction and are capable of moving the transported sheet along the axial direction of the photosensitive drum 41. And a part of the transport path 13 is defined therebetween. The guide member 56 is provided on the casing 35 forming a part of the image forming unit 40, and the guide member 57 is provided on the transport base 33 forming a part of the transfer unit 46.
It is fixed to. The sheet is guided by the guide members 56 and 57, reaches between the photosensitive drum 41 and the transfer roller 47, and passes between them (see the arrow H in FIG. 2).

The image forming unit 40 including the photosensitive drum 41 and the transfer roller 47 are arranged so that the transfer roller 47 is disposed at a predetermined position with respect to the photosensitive drum 41.
The transfer units 46 are positioned and attached to the base member 32 of the housing 30, respectively. On the other hand, the image forming unit 40 is detachable from the base member 32 of the housing 30 and the transfer unit 46 is rotatable to facilitate maintenance such as jam clearance. .

In the present embodiment, when the image forming unit 40 is attached or detached or the transfer unit 46 is rotated, the transfer roller 47 is attached to the photosensitive drum 41 so that it can be positioned again thereafter. A pair of positioning members 61 for positioning with respect to each other are provided on the casing 35 of the image forming unit 40 including the photosensitive drum 41. This allows
The positioning of the transfer roller 47 with respect to the photosensitive drum 41 can be realized with high precision so that the positioning position when the image forming unit 40 or the like is displaced and returned to the original position does not change.

In particular, in the present embodiment, the pair of positioning members 61 and one of the guide members 56 constitute an integral guide unit 60, which is positioned with respect to the photosensitive drum 41 and 35. The details will be described below. In the following description,
With the image forming unit 40 and the transfer unit 46 arranged at predetermined positions on the base member 32, the directions will be described with reference to when viewed from the front. In addition, an arrow X indicating a left-right direction is illustrated in FIG. 1 and each of the drawings described below.

First, the image forming unit 40 and the transfer unit 4
6 will be described. Please refer to FIG. The housing 30 includes a base member 32 serving as a structural member that supports the image forming apparatus 8, the light irradiation unit 9, the paper transport unit 10, and the like.
A plate-shaped transfer base 33 rotatably attached to the left side surface of the base member 32 and forming a part of the transfer path 13 and forming a part of the transfer unit 46;
2, a metal frame (see FIG. 1) composed of an exterior member 31 attached to and surrounding the copying machine 1 to form an exterior of the copying machine 1, and a plurality of metal plate members fixed to a base member 32 to support the upper portion 3 of the apparatus main body 2. Not shown) and the imaging unit 4
And a casing 35 that constitutes a part of the C.O.

The casing 35 is made of resin and is formed in a box shape elongated in the front-rear direction, and directly supports a bearing 71 (see FIG. 3) at both ends in the longitudinal direction. The drums 41 are supported in the vicinity of both ends in the axial direction. The casing 35 is detachably supported by the base member 32. The casing 35 can be attached to the accommodation chamber 62 of the base member 32 from the front along the front-rear direction, and can be pulled out forward. Also, the casing 3
5 is positioned at a predetermined position of the base member 32 when attached to the accommodation chamber 62.

The transport base 33 is supported by the base member 32 so as to be rotatable around a support shaft 34. In FIG. 1, a first position where the outer surface of the transfer base 33 is arranged along the left side surface of the housing 30, and the transfer base 33 is mounted on the housing 3 so that the inner surface of the transfer base 33 is opened.
The transport base 33 can be pivotally displaced to the second position that is tilted with respect to the left side surface of the zero. In the first position, the transport path 13 is defined between the right side surface of the transport base 33 and the left side surface of the base member 32 and the casing 35 attached thereto, and the transport path 13 is closed to the outside. As a result, the transfer roller 47 approaches the photosensitive drum 41 supported by the casing 35 so as to approach and form an image. At the second position, the transport path 13 is opened to the outside, and the peripheral surfaces of the photosensitive drum 41 and the transfer roller 47 are separated from each other,
Jam processing becomes possible.

Although only a part of the base member 32 is not shown, a main plate portion 61 for supporting the light irradiation unit 9 is provided.
And the image forming unit 4 provided on the left side of the main plate portion 61.
It has the above-mentioned accommodation room part 62 surrounding 0 and a support part (not shown) provided at the left end of the accommodation room part 62 and supporting the support shaft 34. An opening for inserting and removing the casing 35 is provided on the front surface of the storage chamber 62. The above-mentioned parts of the base member 32 are made of resin and are integrally formed.

Next, each part of the image forming unit 40 and the transfer unit 46 will be described based on the state at the time of image formation.
Please refer to FIG. 2 and FIG. FIG. 3 is a cross-sectional view of a portion near the rear side of the photosensitive drum 41 and the transfer roller 47 as viewed in the direction of arrow A. The image forming unit 40 includes a casing 35, a positioning member 61, and a guide member 56 in addition to the above-described components such as the photosensitive drum 41. A positioning ring 72 that can rotate integrally and a bearing 71 that is rotatably supported by the casing 35 are provided on both axial sides of the photoconductor drum 41. One end is rotatable integrally. Drive gear 73 is provided. The drive gear 73 is driven by a motor (not shown) to rotate the photosensitive drum 41, and transmits the rotation to the transfer roller 47 via a driven gear 83 that meshes with the drive gear 73.

A rotation center shaft 84 that can rotate integrally with the transfer roller 47 extends from both ends in the axial direction. The rotation center shaft 84 on both sides in the axial direction of the transfer roller 47 is provided with a positioning ring 82 that can rotate integrally with the transfer roller 47 and a bearing 81 that rotatably supports the rotation center shaft 84. , An axial end 8 on the outside in the axial direction.
5 are protruding. Also, on the rear side of the transfer roller 47,
The above-described driven gear 83 is fixed to the rotation center shaft 84 so as to be integrally rotatable.

The transfer roller 47 is held by the transport base 33 and is elastically pushed upward through a bearing 81 by a coil spring 86 as an urging member attached to the transport base 33. By being pushed in this direction, the transfer roller 47 approaches the photosensitive drum 41 so that the transfer roller 47 faces each other (arrow B).
As a result, the peripheral surfaces of the positioning rings 72 and 82 come into contact with each other. At the same time, the transfer roller 47
Abuts on the positioning member 61.

When the positioning ring 82 of the transfer roller 47 and the positioning ring 72 of the photosensitive drum 41 abut on each other, a predetermined gap is formed between the peripheral surfaces of both the transfer roller 47 and the photosensitive drum 41. The two 41 and 47 are positioned so as to face each other so that the center-to-center distance between the two is a predetermined distance while ensuring the above. Positioning member 61
Are arranged corresponding to both ends of the transfer roller 47 in the axial direction, and are fixed to the left side surface of the casing 35 near the transfer roller 47. The positioning member 61 includes a bearing 71
Is positioned in the vicinity of.

When the transport base 33 and the casing 35 are supported by the base member 32 so that an image can be formed, the positioning member 61 is located at a predetermined position on the left side of the photosensitive drum 41 and a predetermined distance below. , Transfer roller 4
The shaft ends 85 near both ends in the axial direction of the transfer roller 47 are positioned in the vertical direction, which is the direction intersecting the direction in which the photoconductor 7 and the photosensitive drum 41 face each other (arrow B). The positioning member 61 includes an upper surface 63 and a lower surface 62.
The upper surface 63 and the lower surface 62 face each other in the vertical direction, and the shaft end 85 of the transfer roller 47 is disposed between the upper surface 63 and the lower surface 62. The shaft end 85 of the transfer roller 47 pressed upward is moved to the lower surface 62 of the positioning member 61.
Abut from below. Thus, the transfer roller 47 is
Since it is pressed against the positioning member 61, it is positioned stably.

The lower surface 62 of the positioning member 61 has a direction in which the shaft end 85 of the transfer roller 47 is pushed and moved when the transfer roller 47 receives a rotational driving force via a pair of gears 73 and 83 (this direction). The direction is the direction in which the sheet is conveyed in the transfer area.), So that the transfer roller 47 receiving the rotational driving force can be positioned more stably. In addition, the space between the upper surface 63 and the lower surface 62 is open toward the left side, which is the side where the transport base 33 is located, and the shaft end 85 of the transfer roller 47 moves in and out as the transport base 33 rotates. It is a passage.

The guide member 56 is provided at both ends in the front-rear direction via the pair of positioning members 61 via the casing 35.
, And arranged at substantially the same position as the positioning member 61 when viewed from the front. In addition, a pair of positioning members 61
It may be fixed to the casing 35 via the guide member 56. During maintenance of the copying machine 1, first, the transport base 33 is tilted down, the shaft end 85 of the transfer roller 47 is separated from the positioning member 61, and the transfer roller 47 is separated from the photosensitive drum 41. At the same time, the guide members 56 and 57 are separated from each other.

When replacing the image forming unit 40, the image forming unit 40 is removed from the accommodation room 62 of the base member 32, and then the replaced image forming unit 40 is attached to the base member 32. Next, when the transport base 33 is returned, the shaft end portion 85 of the transfer roller 47 engages while being pressed against the lower surface 82 of the positioning member 61, and the transfer roller 47 contacts the photosensitive drum 41 and It is positioned at a predetermined position with respect to the guide member 56. At this predetermined position, the center axes of the photosensitive drum 41 and the transfer roller 47 are made parallel by the positioning member 61 and the positioning rings 72 and 82.

As described above, according to the present embodiment, since the positioning member 61 is attached to the casing 35, the transport path 13 is rotated by rotating the transport base 33.
When the shutter is opened and closed, the transfer roller 47 can be stably positioned with respect to the photosensitive drum 41 without a positional shift. As a result, the paper can be stably conveyed, and an image with no variation can be obtained. In particular, the positioning member 61
Is provided in the image forming unit 40, so that the transfer roller 47 can be stably positioned with respect to the photosensitive drum 41 without displacement even when the image forming unit 40 is attached and detached and returned.

Further, since the guide unit 60 is disposed near the bearing 71 in the casing 35 which directly supports the bearing 71, stable positioning with respect to the photosensitive drum 41 can be ensured. Further, since the guide member 56 is provided as a unit together with the positioning member 61 in the casing 35, when the transport path 13 is opened and closed, the guide member 56 is also connected to the photosensitive drum 41 and the transfer roller 4.
As a result, it is possible to obtain an image with even more variation.

For example, the guide member 56 is connected to the photosensitive drum 4
With respect to the transfer area between the transfer roller 1 and the transfer roller 47, the transfer area can be disposed at a position suitable for guiding the paper. As a result, the scattering of the toner in the transfer area due to the guided paper can be prevented. A fine image can be formed. Also,
Since the casing 35, the guide unit 60, and the photosensitive drum 41 constitute the image forming unit 40, they can be arranged close to each other, so that they can be accurately positioned at a predetermined position, and the positioning is easy. Can be simplified.

In particular, the guide unit 60 is connected to the photosensitive drum 4
1, the positioning member 61
The positioning of the three members, that is, the guide member 56 and the photosensitive drum 41, can be realized more easily than in the case where they are separately positioned. The positioning member 61 moves in the vertical direction, which is the direction intersecting the direction in which the transfer roller 47 and the photosensitive drum 41 face each other, in the vertical direction.
Since both shaft end portions 85 are positioned, it is possible to prevent the rotation shafts of the transfer roller 47 and the photosensitive drum 41 from tilting. In addition to this, the transfer roller 47 and the photosensitive drum 4
As a result, the rotation axes can be arranged in parallel with each other, and a clear image can be obtained.

Further, since the pair of guide members 56 and 57 are provided in separate units and can be separated from each other, it is easy to clear the jam. Note that the casing 35 is formed of the base member 3.
2, it was attached and detached by being inserted and removed in the front-rear direction, but is not limited to this. Further, the transport base 33 rotates with respect to the base member 32, but is not limited thereto. In short, if the transport base 33 and the casing 35 are connected to each other so as to be displaceable, the operation and effect of the present invention can be obtained.

The transfer roller 47 is connected to the photosensitive drum 4
1 or may be arranged with a predetermined gap from the peripheral surface of the photosensitive drum 41.
In short, the present invention can be applied to the image forming apparatus 8 as long as it can displace and position the transfer roller 47 with respect to the photosensitive drum 41. Further, the above-described image forming apparatus has been applied to a copying machine, but may be applied to a printer, a facsimile, and the like.

In addition, various design changes can be made without changing the gist of the present invention.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a schematic configuration of a copying machine showing an embodiment of the present invention.

FIG. 2 is an enlarged front sectional view of a portion near a transfer roller and a photosensitive drum shown in FIG. 1;

FIG. 3 is a cross-sectional view of a portion near an axial end of a transfer roller and a photosensitive drum when viewed from a direction A shown in FIG. 2;

[Description of Signs] 8 Image forming apparatus 13 Conveying path 33 Conveying base 35 Casing 41 Photoconductor drum 47 Transfer roller 56 Guide member 60 Guide unit 61 Positioning member 85

Claims (2)

[Claims] A photosensitive drum that forms a toner image on the surface while rotating; a transfer roller that transfers the toner image on the surface of the photosensitive drum to a sheet while rotating opposite to the photosensitive drum; A casing that supports both ends in the axial direction; and a transport base that holds a transfer roller while forming a transport path for the paper between the casing and the transport base. The transport base closes the transport path so that an image can be formed. An image that is displaceably connected to the casing at a position where the transfer roller approaches and is opposed to the photosensitive drum and at a position where the transfer path is opened and the transfer roller is separated from the photosensitive drum. In the forming apparatus, when the conveyance path is closed and the conveyance base is arranged, a positioning member for positioning the vicinity of both ends in the axial direction of the transfer roller with respect to the photosensitive drum is provided on the casing. Image forming apparatus characterized by being kicked. 2. The image forming apparatus according to claim 1, wherein the casing is provided with a guide member for guiding the sheet between the transfer roller and the photosensitive drum. An image forming apparatus comprising an integrated unit, wherein the unit is positioned at a predetermined position with respect to the photosensitive drum.