JP4635078B2 - Image forming apparatus - Google Patents

Description

  The present invention transfers a toner image on an image carrying rotator to a transfer material by passing the transfer material through a transfer nip between an image carrying rotator carrying a toner image and a counter rotator facing the image carrying rotator. The present invention relates to a transfer device, and an image forming apparatus such as a copying machine, a printer, a facsimile, and a plotter having the transfer device.

Japanese Patent Laid-Open No. 9-114277 discloses a static elimination needle for reducing the charge of a transfer material that has passed through a transfer nip, in the vicinity of the downstream of the transfer roller as an elastic roller that is pressed against a photosensitive drum to form a transfer nip. In this configuration, the relative positional relationship between the transfer roller and the charge reduction unit can be kept constant regardless of the backlash of a movable member such as a cover that supports the transfer roller. The intended transfer device is described.
A static elimination needle is provided on a holder rotatably provided on the rotation shaft of the transfer roller, a spring contact connected to a power source is provided on the inner surface of the cover that supports the transfer roller, and the holder is biased by the spring contact. This is brought into contact with a process cartridge having a photosensitive drum, thereby making the positional relationship between the transfer roller and the static elimination needle constant.

JP-A-9-114277 JP-A-8-160840 (Patent No. 3294030) JP 2002-123151 A

With the configuration described in Patent Document 1, even if the cover is not fully attached to the image forming apparatus main body, the error is absorbed by the biasing force of the spring contact.
However, since the pressing direction of the transfer roller against the photosensitive drum (the biasing direction via the elastic force of the roller when the cover is closed) and the biasing direction of the spring contact are the same, the biasing force of the spring contact is photosensitive. There is a problem in that the press contact state between the body drum and the transfer roller is affected, and the position and width of the transfer nip change with time, resulting in a decrease in transferability.

  Accordingly, the present invention has as its main object to provide a transfer device capable of maintaining good transferability over a long period of time even with a structure having a charge reduction function of a transfer material, and an image forming apparatus having the transfer device. To do.

In order to achieve the above object, the invention according to claim 1 is configured to be movable between a first position that is closed with respect to the apparatus main body and a second position that is opened outward with respect to the apparatus main body. An opening / closing body that is provided in the apparatus main body and that carries a toner image, an opposing rotation body that is provided in the opening / closing body and faces the image carrying rotation body,
The image bearing rotating body is pressed against the image bearing rotating body to form a transfer nip between the image bearing rotating body and the counter rotating body, and a transfer material is passed through the transfer nip. An image forming apparatus in which a toner image on a body is transferred to the transfer material, and when the opening / closing body is in the second position, the image bearing rotating body and the counter rotating body are separated from each other, and the transfer nip is opened. And a second electrical contact provided on the opening / closing body and contacting the first electrical contact when the opening / closing body is in the first position; , wherein the said first electrical contact the second electrical contact is in contact with the elastic force, the direction of the urging force acting between the two electrical contacts up direction der substantially orthogonal to the pressure-contacting direction, the second Are connected to the electrical contacts of the Characterized in that it comprises a conductive member provided in timber transport path.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect , when the opening / closing body is in the second position, the first electrical contact and the second electrical contact are separated from each other. Features.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the direction of the urging force acting between the two electrical contacts is the direction of the rotation axis of the counter rotating body .

According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the first electrical contact is grounded .

According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the first electrical contact is electrically connected to a power source .

In the invention of claim 6, wherein, in the image forming apparatus according to claim 1, wherein the conductive member is characterized by a charge removing member for reducing the charge of the transfer material having passed through the transfer nip.

According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, the image carrying rotator is an intermediate transfer belt supported by a plurality of rollers, and the counter rotation The body is a secondary transfer member, and has bias applying means for applying a transfer bias to the intermediate transfer belt via a rotation shaft of a roller provided at a position facing the secondary transfer member among the plurality of rollers. It is characterized by that.
In the invention of claim 8, wherein, in the image forming apparatus according to any one of claims 1 to 6, wherein the image bearing rotation body is a transfer belt between the medium, the counter rotator secondary transfer member A third electrical contact provided on the apparatus main body, and provided on the opening / closing body side, and electrically connected to the third electrical contact when the opening / closing body is in the first position and A fourth electric contact for applying a bias to the secondary transfer member, and the third electric contact and the fourth electric contact abut against each other by an elastic force, and an urging force acting between the two electric contacts. The direction of is a direction substantially orthogonal to the pressure contact direction .
In the invention of claim 9, wherein, in the image forming apparatus according to any one of claims 1 to 8, one of said second electrical contact with said first electrical contact is other abutting It has a contact part, and the slope part which inclines in the direction of the urging | biasing force which this contact part receives from said other with respect to the said contact part, It is characterized by the above-mentioned .

According to the present invention, the urging force of the electrical contact affects the pressure contact state between the image bearing rotator and the counter rotator, thereby preventing the transfer property from deteriorating due to changes in the position and width of the transfer nip with time. Can It is possible to prevent deterioration in transferability due to a transfer nip position shift or the like over a long period . Also, it is possible to improve the transferability of the toner image to the transfer material.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
First, an outline of the configuration of a color printer as an image forming apparatus in the present embodiment will be described with reference to FIG. A transfer belt unit 10 having an intermediate transfer belt 11 as an image bearing rotating body and four image stations are arranged at the center of the apparatus main body.
Each image station has photosensitive drums 20Y, 20C, 20M, and 20Bk as image carriers, around which are dedicated charging devices 30Y, 30C, 30M, and 30Bk, developing devices 50Y, 50C, 50M, and 50Bk, Cleaning devices 40Y, 40C, 40M, and 40Bk are arranged.
A toner bottle group 9 for replenishing toner is provided at the upper part of the apparatus main body. Each toner bottle is filled with toners of yellow (Y), cyan (C), magenta (M), and black (Bk) from the left in the drawing. Each color developing device 50Y, 50C, 50M, 50Bk is replenished.

A printing operation will be described. The transfer paper 2 as a transfer material (recording medium) is fed from the paper feed cassette 1 by the paper feed roller 3, and when the leading edge of the transfer paper 2 reaches the resist roller pair 4, it is detected by an unillustrated sensor. The transfer sheet 2 is conveyed to the nip portion between the secondary transfer roller 5 and the intermediate transfer belt 11 by the registration roller pair 4 while taking the timing.
The photosensitive drums 20Y, 20C, 20M, and 20Bk uniformly charged in advance by the charging devices 30Y, 30C, 30M, and 30Bk are exposed and scanned with laser light by the optical writing device 8, and the photosensitive drums 20Y, 20C, and An electrostatic latent image is created on 20M and 20Bk.

The electrostatic latent images are developed by the developing devices 50Y, 50C, 50M, and 50Bk for the respective colors, and yellow, cyan, magenta, and black toner images are formed on the surfaces of the photosensitive drums 20Y, 20C, 20M, and 20Bk. .
Next, a primary transfer voltage is applied to the primary transfer rollers 12Y, 12C, 12M, and 12Bk, and the toner on the photosensitive drums 20Y, 20C, 20M, and 20Bk is sequentially transferred onto the intermediate transfer belt 11. At this time, the image forming operation for each color is executed while shifting the timing from the upstream side toward the downstream side so that the toner image is transferred to the same position on the intermediate transfer belt 11.

The image formed on the intermediate transfer belt 11 is transported to the position of the secondary transfer roller 5 as the counter rotating member and is secondarily transferred onto the transfer paper 2 at once. The transfer paper 2 onto which the toner images of the respective colors have been transferred is conveyed to the fixing device 6 and fixed by heat and pressure, and is discharged by a paper discharge roller pair 7 onto a paper discharge tray 15 that forms the upper surface of the apparatus main body.
The residual toner on the photoconductive drums 20Y, 20C, 20M, and 20Bk is cleaned by the respective cleaning devices 40Y, 40C, 40M, and 40Bk, and then the charging device 30Y, in which the bias of the AC component is superimposed and applied to the direct current. 30C, 30M, and 30Bk are charged simultaneously with static elimination to prepare for the next image formation.
The residual toner on the intermediate transfer belt 11 is cleaned by the intermediate transfer belt cleaning device 13 to prepare for the next image forming process.

The intermediate transfer belt 11 includes a driving roller 21, a driven roller 22 facing the intermediate transfer belt cleaning device 13, a transfer sheet 2 from the registration roller pair 4 at a transfer nip between the secondary transfer roller 5 and the intermediate transfer belt 11. Is substantially supported by an entrance roller 23 that forms the entrance shape of the intermediate transfer belt 11.
The transfer device is constituted by the driving roller 21, the intermediate transfer belt 11, the secondary transfer roller 5, and the like.

The configuration of each image station will be described in detail with reference to FIG. In addition, it demonstrates without attaching the code | symbol according to color. The charging device 30 is a charging roller disposed in contact with or close to the photosensitive drum 20, and a cleaning roller 31 is provided in contact with the charging device 30.
The developing device 50 includes agitating and conveying members 53 and 54 for agitating and conveying the developer contained in the developing casing 55 to circulate, and the developer is supplied from the agitating and conveying member 53 to the developing roller 51. Toner is supplied from the developing roller 51 to the photosensitive drum 20. Reference numeral 52 denotes a doctor blade that regulates the layer thickness of the developer on the developing roller 51.
The cleaning device 40 includes a cleaning casing 43, a cleaning blade 41, a collecting member 42 that conveys and collects the scraped toner, and the like. In FIG. 6, symbol L indicates the laser beam from the optical writing device 8, and symbol 14 indicates the frame of the transfer belt unit 10. The transfer belt unit 10 is driven by a drive mechanism (not shown) so that the intermediate transfer belt 11 contacts the photosensitive drum 20 during image transfer, and after the transfer, the intermediate transfer belt 11 is driven away from the photosensitive drum 20. Is done.

As shown in FIG. 4, the secondary transfer roller 5 is rotatably supported by a support member 60 formed in a casing shape having a housing recess. In addition to the secondary transfer roller 5, the support member 60 includes a guide member 61 for conveying and guiding the transfer paper 2 to the transfer nip between the intermediate transfer belt 11 and the secondary transfer roller 5, and the transfer paper from the intermediate transfer belt 11. A neutralizing needle 62 as a conductive member for separating 2 and a handle 63 for performing operations such as attaching / detaching and transporting the support member 60 are provided. The static elimination needle 62 is provided such that its needle-shaped portion abuts (contacts) the transfer paper 2 after passing through the transfer nip.
The support member 60 is detachably provided on a cover member 65 that can be opened and closed in the direction of an arrow 64 shown in FIG. 5. When the cover member 65 is opened, the intermediate transfer belt 11 and the secondary transfer roller 5 are separated and transferred. The nip is opened.

The support member 60 is pivotally supported with its lower end pivotally supported with respect to the cover member 65, and the intermediate transfer belt 11 by a coil spring 66 as an urging means that is restricted by the cover member 65 at one end side. It is urged to the side. The coil springs 66 are arranged at two locations on both ends in the axial direction of the secondary transfer roller 5.
Due to the urging force (pressing force) of the coil spring 66, the secondary transfer roller 5 is pressed against the intermediate transfer belt 11 in the direction of arrow 67 to form a transfer nip.
In FIG. 3, reference numeral 68 indicates a bias applying unit that applies a bias to the intermediate transfer belt 11. The bias applying unit 68 constitutes a part of the transfer device, and applies a bias to the driving roller 21 as a bias applying roller via the shaft portion.
The shaft portion of the drive roller 21 is made of a conductive material (for example, stainless steel), and the bias applied to the drive roller 21 is directed to the intermediate transfer belt 11, the transfer paper 2, the secondary transfer roller 5, and the charge removal needle 62. Conduction is possible.

As shown in FIG. 1, an electrical contact 69 is formed on one end side of the support member 60 in the axial direction of the secondary transfer roller 5 and is formed by raising the end of the static elimination needle 62 vertically. The conductive elastic member 70 is in contact with 69. The electrical contact 69 is electrically connected to the surface of the secondary transfer roller 5. In FIG. 1, reference numeral 68 a indicates a contact piece of the bias applying means 68 with respect to the shaft portion of the driving roller 21.
As shown in FIG. 2, the conductive elastic member 70 has a base end fixed to a frame 71 of the apparatus main body with bolts 72 and connected to a power source (not shown) and a free end side of the base 73. It has a fixed leaf spring 74. The leaf spring 74 has an elastically deformable shape whose tip is bent in a horizontal plane, and a part of the leaf spring 74 is in contact with the electrical contact 69 and the contact with respect to the contact The inclined portion 74 a is inclined in the direction of the urging force received from the electrical contact 69 .

As shown in FIG. 1, the direction of the urging force due to elastic deformation of the inclined surface portion 74 a in a state where the contact portion 74 a-1 of the leaf spring 74 is in contact with the electrical contact 69 is substantially the same as the axial direction of the secondary transfer roller 5. The direction of the arrow 75 is a direction substantially perpendicular to the pressing direction 67 of the secondary transfer roller 5 against the intermediate transfer belt 11 or the urging direction by the coil spring 66.
Thereby, the force applied to the electrical contact 69 does not affect the force applied to the secondary transfer roller 5 by the coil spring 66. The charge eliminating needle 62 is supplied with a bias via the conductive elastic member 70, and the transfer sheet 2 charged through the transfer nip is brought into contact with the charge eliminating needle 62 to reduce the charge.
In this embodiment, the electrical contact 69 is configured by raising the end of the static elimination needle 62, but the electrical contact 69 may be provided separately and electrically connected to the static elimination needle 62.

A second embodiment will be described with reference to FIGS. The same parts as those in the above-described embodiment are denoted by the same reference numerals, and unless otherwise specified, the description of the configuration and functions already described is omitted, and only the main part will be described (the same applies to other embodiments below).
An electrical contact 76 is formed on one end side of the support member 60 in the axial direction of the secondary transfer roller 5, using the end portion of the static elimination needle 62 that extends horizontally as it is, and the electrical contact 76 has a conductive elastic member 77. Is in contact from above.
As shown in FIG. 8, the conductive elastic member 77 has a base end fixed to a frame (not shown) of the apparatus main body and a base 78 connected to a power source (not shown) and a free end of the base 78. A plate spring 79 is provided. The leaf spring 79 has an elastically deformable contact portion 79a that is bent and formed in a vertical plane at a tip portion thereof, and a part of the leaf spring 79 is a contact surface 79a-1 that contacts the electrical contact 76.

As shown in FIG. 9, the direction of the urging force due to the elastic deformation of the contact portion 79 a in a state where the contact surface 79 a-1 of the leaf spring 79 is in contact with the electrical contact 76 is applied by the coil spring 66 as indicated by an arrow 80. The direction is substantially perpendicular to the direction of force.
Thus, the force applied to the electrical contact 76 does not affect the force applied to the secondary transfer roller 5 by the coil spring 66. The charge eliminating needle 62 is supplied with a bias via the conductive elastic member 77, and the transfer sheet 2 charged through the transfer nip is brought into contact with the charge eliminating needle 62 to reduce the charge.
In the present embodiment, the electrical contact 76 is configured to use the horizontal end portion of the static elimination needle 62 as it is, but the electrical contact 76 may be provided separately and connected to the static elimination needle 62.

FIG. 10 shows a third embodiment. In the present embodiment, the contact piece 81 electrically connected to the static elimination needle 62 is in contact with the peripheral surface of the rotation shaft 5 a of the secondary transfer roller 5. The rotation shaft 5a of the secondary transfer roller 5 is formed of a conductive material such as stainless steel, and the end surface of the rotation shaft 5a becomes an electrical contact 82. The electrical contact 82 is in contact with a ground plate 83 as a conductive elastic member whose base end is supported by the frame of the apparatus main body. The ground plate 83 biases the rotary shaft 5a in the axial direction (the direction of the arrow 84).
The direction of the urging force by the ground plate 83 is a direction substantially orthogonal to the urging direction by the coil spring 66. Thereby, the force applied to the electrical contact does not affect the force applied to the secondary transfer roller 5 by the coil spring 66.

  In the first and second embodiments, the conductive elastic member is connected to the power source. However, the conductive elastic member may be grounded. In addition, a bias applying unit that applies a bias to the secondary transfer roller 5 may be provided.

It is a perspective view which shows the principal part of the transfer apparatus in the 1st Embodiment of this invention. It is a perspective view of a conductive elastic member. FIG. 4 is a diagram illustrating a configuration for applying a bias to an image bearing rotator and a pressure contact state between the image bearing rotator and an opposing rotator. It is a perspective view of the support member holding the secondary transfer roller. 1 is a schematic front view of a color printer as an image forming apparatus. It is a detailed view of an image station. It is a perspective view which shows the principal part of the transfer apparatus in 2nd Embodiment. It is a perspective view of the electroconductive elastic member in 2nd Embodiment. It is a principal part front view in 2nd Embodiment. It is a perspective view which shows the principal part of the transfer apparatus in 3rd Embodiment.

Explanation of symbols

2 Transfer paper as transfer material 5 Secondary transfer roller as counter rotating body 11 Intermediate transfer belt as image carrying rotating body 62 Static elimination needle as conductive member 68 Bias applying means 69, 76, 82 Electrical contacts 70, 77 Conductive Conductive elastic member 83 Ground plate as conductive elastic member

Claims (9)

An opening / closing body configured to be movable to a first position that is closed with respect to the apparatus main body and a second position that is opened outward with respect to the apparatus main body;
An image carrying rotator provided in the apparatus main body and carrying a toner image;
An opposing rotating body provided on the opening / closing body and facing the image bearing rotating body;
With
The counter rotator and the image bearing rotator are pressed against each other, a transfer nip is formed between the image bearing rotator and the counter rotator, and a transfer material is passed through the transfer nip. Transfer the toner image to the transfer material,
In the image forming apparatus in which, when the opening / closing body is in the second position, the image bearing rotating body and the counter rotating body are separated from each other, and the transfer nip is opened.
A first electrical contact provided in the apparatus body;
A second electrical contact provided on the opening / closing body and abutting on the first electrical contact when the opening / closing body is in the first position;
With
Wherein the first electrical contact the second electrical contact is in contact with the elastic force, the direction of the urging force acting between the two electrical contacts up direction der substantially orthogonal to the pressing direction,
An image forming apparatus comprising: a conductive member connected to the second electrical contact and provided in a transfer material conveyance path downstream of the transfer nip . The image forming apparatus according to claim 1.
The image forming apparatus, wherein the first electrical contact and the second electrical contact are separated from each other when the opening / closing body is in the second position. The image forming apparatus according to claim 1 or 2,
The image forming apparatus according to claim 1, wherein the direction of the urging force acting between the two electrical contacts is in the direction of the rotation axis of the counter rotating body. The image forming apparatus according to any one of claims 1 to 3,
The image forming apparatus, wherein the first electrical contact is grounded. The image forming apparatus according to any one of claims 1 to 3,
The image forming apparatus, wherein the first electrical contact is electrically connected to a power source. The image forming apparatus according to claim 1 .
The image forming apparatus according to claim 1, wherein the conductive member is a charge eliminating member that reduces a charge of the transfer material that has passed through the transfer nip . The image forming apparatus according to any one of claims 1 to 6 ,
The image bearing rotator is an intermediate transfer belt supported by a plurality of rollers, and the counter rotator is a secondary transfer member,
An image forming apparatus comprising bias applying means for applying a transfer bias to the intermediate transfer belt via a rotation shaft of a roller provided at a position facing the secondary transfer member among the plurality of rollers . The image forming apparatus according to any one of claims 1 to 6 ,
Said image bearing rotary member is a transfer belt between the medium, the opposing rotating member is a secondary transfer member,
A third electrical contact provided in the apparatus main body, and provided on the opening / closing body side, and electrically connected to the third electrical contact and the secondary transfer when the opening / closing body is in the first position A fourth electrical contact for applying a bias to the member;
3. The image forming apparatus according to claim 1, wherein the third electrical contact and the fourth electrical contact are brought into contact with each other by an elastic force, and a direction of an urging force acting between the both electrical contacts is a direction substantially orthogonal to the pressure contact direction . The image forming apparatus according to any one of claims 1 to 8 ,
One of the first electrical contact and the second electrical contact is a contact portion that contacts the other, a slope portion that inclines toward the urging force that the contact portion receives from the other with respect to the contact portion, an image forming apparatus, comprising a.

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