JPH07248685A - Transfer device - Google Patents

Abstract

PURPOSE:To provide a transfer device preventing the pollution of the transfer device due to a toner left on an image carrier and having a few number of part items and a simple structure at a low cost by moving a cylindrical thin film member near or apart from the image carrier via the stiffness and moving force due to the loosening of the transfer member synchronously with the infiltration of the transfer member. CONSTITUTION:This transfer device 18 is provided with a support member 181 arranged to face a photoreceptor 1 and applied with transfer voltage, a cylindrical thin film member 182 having a circumferential length slightly longer than the circumferential length of the support member 181 and idly coupled with the support member 181, and a rockable moving member 183 pushing up the cylindrical thin film member 182 pressed by the transfer paper 16 and located at a position apart from the photoreceptor 1 when the transfer paper 16 enters a transfer section B formed between the photoreceptor 1 and the cylindrical thin film member 182 toward the photoreceptor 1 and releasing the push-up of the cylindrical thin film member 182 when the transfer paper 16 passes through the transfer section B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device used in an image forming apparatus such as a transfer type electrophotographic copying machine, a transfer type electrophotographic facsimile and a printer, and more specifically, a toner image formed on an image carrier. The present invention relates to a transfer device for transferring and outputting the image on a transfer member.

[0002]

2. Description of the Related Art As a transfer device, for example, Japanese Patent Laid-Open No. 63-63
No. 25672 (hereinafter referred to as “conventional example 1”), JP-A No. 1-284884 (hereinafter referred to as “conventional example 2”), and JP-A No. 2-14876 (hereinafter referred to as “conventional example 3”). What has been done is known. The transfer device described in the conventional example 1 is arranged so as to face a photoconductor as an image carrier, and a transfer roller supported by a support is moved up and down by a cam to contact and separate from the image carrier. In the transfer device described in Example 2, a gap is provided between the transfer roller and the photoconductor, and the transfer is performed without direct contact between the transfer roller and the photoconductor at the time of transfer. Further, in the transfer device described in the conventional example 3, the transfer roller arranged so as to face the photoconductor is moved by the drive means centering on the solenoid so as to be brought into contact with and separated from the photoconductor.

[0003]

Among the above-mentioned transfer devices, in the transfer device of the first conventional example, the support for supporting the transfer roller is moved up and down by the cam to bring the transfer roller into contact with and separate from the photoconductor. Since a cam and its drive mechanism are required, there are problems that the number of parts is large, the cost is high, and the timing of the cam drive is difficult to adjust. In the transfer device of the conventional example 2, since a gap of about the thickness of the transfer member is set between the photoconductor and the transfer roller, only a transfer paper having a limited thickness suitable for the gap can be used for the transfer member. There are problems such as narrow paper selection and difficult gap management. In the transfer device of the conventional example 3, since the contacting / separating operation of the transfer roller to / from the photosensitive member is performed by the driving means centering on the solenoid, the structure becomes complicated, and the cost is increased due to the increase in the number of parts, and the solenoid driving is performed. There is a problem that it is difficult to adjust the timing. In the transfer device of the above-mentioned configuration, in which the photoconductor and the transfer roller are in contact with each other, the transfer paper causes a jam for some reason and is conveyed to the transfer portion formed between the transfer roller and the photoconductor. Otherwise, the toner remaining on the image carrier adheres to the transfer roller or the like and causes a transfer failure. The present invention has been made in view of the above problems, and an object of the present invention is to provide a tubular thin film member by synchronizing the movement of a transfer member with the slack of the transfer member and the moving force. By contacting and separating the
An object of the present invention is to provide a low cost transfer device having a simple structure with a small number of parts while preventing the transfer device from being contaminated by the toner remaining on the image carrier.

[0004]

Therefore, in a transfer device for transferring a toner image formed on an image carrier to a transfer member according to claim 1, a transfer voltage opposite to the image carrier is applied. A supporting member, a cylindrical thin film member having a peripheral length slightly longer than that of the supporting member and loosely fitted to the supporting member, and the cylindrical thin film member being in contact with the image carrier. And a contacting / separating member that moves in a separating direction. Claim 2
In the invention described above, at least one contacting / separating member is provided on the entrance side or the discharge side of the transfer member, with the transfer section formed between the image carrier and the tubular thin film member being sandwiched therebetween. According to the third aspect of the invention, the claw portions formed by the contacting / separating member toward the entrance side of the transfer member and the discharge side of the transfer member with the transfer portion interposed therebetween face the passage of the transfer member. In the invention described in 5, the contacting / separating member is made of a conductive member and is grounded. According to the invention of claim 6, the tubular thin film member is placed in an initial state in which the contacting / separating member is pressed by the transfer member as the transfer member enters the transfer portion and is in contact with the support on the image carrier side. From the opposite side of the transfer section to sandwich the transfer member with the image carrier, and toward the direction in which the tubular thin film member is lifted when the transfer member has finished passing through the transfer section. The transfer member swings as the transfer member moves. In the invention according to claim 7, a frictional resistance portion is formed at a contact portion of the claw portion with the transfer member.

[0005]

According to the first aspect of the present invention, the cylindrical thin film having a peripheral length slightly longer than the peripheral length of the supporting member, which is arranged so as to face the image carrier and is loosely fitted to the supporting member to which the transfer voltage is applied. When the member is moved by the contacting / separating member in the direction of coming into contact with the image carrier, the cylindrical thin film member is deformed and comes into contact with the image carrier. In the inventions according to claims 2, 3, and 6, when the transfer member enters the transfer portion, the transfer member comes into contact with a claw portion formed on the contact and separation member and extending toward the entrance side of the transfer member, and the contact and separation member is The tubular thin film member is rocked and pushed up toward the image carrier, and the transferred transfer member is sandwiched between the tubular thin film member and the image carrier. When the transfer member passes through the transfer portion, the contact between the claw portion and the transfer member disappears, so that the contact / separation member swings by its own weight as the cylindrical thin film member pushed up is separated from the image carrier. According to the inventions of claims 4 and 5,
Since the contacting / separating member is made of a conductive member and grounded, when the transfer member comes into contact with the claw portion, the transfer voltage applied via the tubular thin film member at the transfer portion is removed. Claim 7
In the above-described invention, the friction resistance portion formed on the claw portion increases the contact resistance between the transfer member and the claw portion, and the slip of the transfer member on the claw portion is reduced.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, referring to FIG. 1, a schematic structure of an image forming apparatus having a transfer device as an embodiment of the present invention will be described. Reference numeral 1 indicates a photoconductor as an image bearing member. As the photoconductor 1, a photoconductive organic photosensitive layer provided on a conductive cylindrical drum is used.

The photosensitive member 1 is rotationally driven in the clockwise direction in the figure by a motor as a driving means (not shown).
An original to be copied is placed on the lath 2 with the contact arranged above the photoconductor 1, and when a Prince switch (not shown) is pressed, a scanning optical system 5 including an original illumination light source 3 and a mirror 4, The scanning optical system 8 including the mirrors 6 and 7 moves to read and scan the document. This scanning light is transmitted to the image reading element 10 provided behind the lens 9,
It is read as an image signal, digitized, and image processed. Then, based on the image-processed signal, a laser diode (LD) (not shown) is driven so that the laser light emitted from the diode is reflected by the holygon mirror 11, and then the photoreceptor 1 is passed through the mirror 12.
Irradiated on. As a result, optical writing (exposure scanning) by the laser light is performed on the peripheral surface of the photoconductor 1. Photoconductor 1
The peripheral surface of is already uniformly charged by the charging charger 13 arranged in the vicinity of the transfer member, and an electrostatic latent image is formed on the photoconductor 1 by this exposure scanning. The formed electrostatic latent image is visualized by the developing device 14. This visible image is transferred by the transfer device 18 onto the transfer paper 16 as a transfer member that is fed from the paper feed unit 15. The transfer paper 16 on which the image has been transferred is separated from the surface of the photoconductor 1 and conveyed to the fixing roller pair 19 by the conveyor belt device 17, and the transfer image is fixed by the roller pair 19 and then transferred to the outside of the apparatus. Is discharged to. After the transfer, the photoconductor 1
The developer remaining on the surface of the transfer member is removed by the cleaning device 20, and is uniformly charged again by the charging charger 13 in preparation for the next exposure.

Next, the transfer device 18 will be described in detail. As shown in FIGS. 2 and 3, the transfer device 18 includes a transfer roller 181, a cylindrical thin-film member 182, and a cylindrical thin-film member 182 which are arranged near the photosensitive member 1 so as to face the photosensitive member 1. The main components are a contacting / separating member 183 for vertically moving and a stopper 184 for holding the member 183 at the transfer paper receiving position.

The transfer roller 181 is arranged in parallel with the photoconductor 1 and its length is set to be substantially the same as the width of the photoconductor 1. The transfer roller 181 is composed of a conductive member, is connected to a high voltage power supply 185, and is adapted to supply a transfer bias voltage at appropriate times. The transfer roller 181 is arranged so as to form a constant gap with the photoconductor 1.

The inner diameter of the cylindrical thin film member 182 is slightly larger than the outer diameter of the transfer roller 181, and its length is substantially the same as the entire length of the transfer roller 181. Cylindrical thin film member 182
2 is a cylindrical thin film member 18 that is the same as the photoconductor 1 as shown in FIG.
Below the transfer portion B formed between the two, it is normally mounted so as to be hung on the transfer roller 181 by its own weight. This state is the initial state of the tubular thin film member 182.
The tubular thin film member 182 is made of hydrin rubber, which is an elastic material having good smoothness and a small friction coefficient, and has a single-layer structure. The thickness of the tubular thin film member 182 is 0.1 mm.
˜0.3 mm is preferable, and its volume resistivity is preferably 10 ⁵ to 10 ¹² Ω · cm. Specific materials satisfying such conditions include, in addition to hydrin rubber, those in which carbon is dispersed in a fluororesin and those in which carbon is dispersed in a polycarbonate resin.
Further, the layered structure of the tubular thin film member 182 may be a two-layered structure in addition to the single layered structure, but the volume resistivity is 10 ⁵ to.
It is desirable to set it within the range of 10 ¹² Ω · cm.

A transfer sheet 16 enters the transfer section B shown in FIGS. 2 and 3 from the right side of the drawing and passes toward the left side with the section B as a boundary. Here, the right side of the drawing is the entrance side C of the transfer paper 16, and the left side is the discharge side D of the transfer paper 16.

The contacting / separating member 183 is a container having a substantially U-shaped cross section that surrounds the transfer roller 181 and the tubular thin film member 182 from the entrance side C and the discharge side D, and has the transfer roller 1 on the inner bottom thereof.
A protrusion A bulging toward 81 is formed. The contact / separation member 183 is made of a conductive member and is grounded. At the upper ends of the side plates 183a and 183b located on the entrance side C and the discharge side D of the contact / separation member 183, outwardly bent claws 18A and 18B are formed, respectively. As shown in FIG. 4, on the upper surfaces of the claw portions 18A and 18B, uneven portions 18C are formed as frictional resistance portions for increasing the contact resistance at the time of contact with the transfer paper 16. The contacting / separating member 183 is provided on the immovable member (not shown).
It is swingably supported by 6, and normally leans toward the entry side C by its own weight.

The stopper 184 is disposed on the entrance side C, and regulates the swing of the contacting / separating member 183 so that the claw portion 18A faces the entrance path E of the transfer paper 16. That is, as shown in FIG. 2, the contacting / separating member 183 has a claw above the line OE connecting the lower paper feed guide 21 forming the approach path E and the contact point O between the photoconductor 1 and the cylindrical thin film member 182. It is held at the transfer paper receiving position where the portion 18A is located. Further, in the claw portion 18B, the contact / separation member 183 is the tubular thin film member 1 shown in FIG.
The transfer paper 1 that has finished the transfer is transferred to the discharge path F of the transfer paper 16 that is formed on the discharge side D when the transfer paper 1 is in the transfer position for pushing up 82.
It is supposed to guide 6. That is, the claw portions 18A,
18B is arranged on the path EF of the transfer paper 16.

The projection A has a cylindrical thin film member 1 when the contacting / separating member 183 placed at the transfer paper receiving position (FIG. 2) swings counterclockwise about the pin 186 as a fulcrum in FIG.
A protrusion that pushes up 82 to press it against the photoconductor 1,
When the contacting / separating member 183 is at the transfer paper receiving position, it occupies a position where it does not contact the tubular thin film member 182. An insulator 187 is provided on the protrusion A. In particular,
Attach an insulating material with a low friction coefficient, such as Teflon (trade name) tape. In addition, means such as embedding an insulating member in the bottom portion of the contacting / separating member 183 and molding the protrusion A can be considered.

The operation of the transfer device 18 having such a configuration will be described. The state of the transfer device 18 shown in FIG.
3 shows an initial state of the transfer device 18 which is a state before the entry.
When a switch (not shown) is pressed to start a copying operation, a toner image is formed on the photoconductor 1 by the well-known image forming process described above, and a transfer bias is applied to the transfer roller 181. At this time, the transfer paper 16 is fed toward the transfer portion B from the paper feeding portion 15 at a predetermined timing in synchronization with the image forming process. Transfer paper 16 fed
However, when reaching the vicinity of the transfer portion B from the approach side C through the approach path E, the transfer paper 16 contacts the upper surface of the claw portion 18A facing the approach path E. At this time, due to the contact frictional force between them, the moving force of the transfer paper 16, and the stiffness of the transfer paper 16 that bends when contacting the claw portion 18A, the claw portion 18A is pushed in the moving direction of the transfer paper, and the contact / separation member 183 is moved. It oscillates counterclockwise around the pin 186 toward the discharge side D and occupies the transfer position. When the contacting / separating member 183 occupies the transfer position, the protrusion A moves from the position shown in FIG. 2 to the position shown in FIG. 3, and pushes up the cylindrical thin film member 182 hanging downward toward the photoconductor 1. The cylindrical thin-film member 182 pushed up presses the transfer paper 16 moving to the transfer portion B while pressing the contacting / separating member 183, as shown in FIG.

The transfer bias applied to the transfer roller 181 is supplied to the transfer paper 16 via the cylindrical thin film member 182, so that the toner image on the photoconductor 1 is transferred to the transfer paper 16. In addition, since the tubular thin film member 182 is a thin film,
When the transfer paper 16 is pressed, the transfer paper 16 is deformed along the peripheral surface of the photoconductor 1 to form a nip portion, and the transfer paper 16 is pressed against the photoconductor 1 with a softer pressing force than a general transfer roller or the like. That is, the photoconductor 1, the transfer paper 16, and the tubular thin film member 1
Since the contact surface with 82 is wide, uniform transfer is possible. As described above, when the cylindrical thin film member 182 presses the transfer paper 16 between itself and the photoconductor 1, the cylindrical thin film member 182 deforms along the peripheral surface of the photoconductor 1, so that the thickness of the transfer paper 16 varies. Even if there is, it can absorb the variation. Therefore, it is not necessary to strictly set the distance between the photoconductor 1 and the cylindrical thin film member 182 in the transfer portion B to a specific paper thickness as in the conventional case, but it can be set with a certain width.

The front end of the transfer paper 16 on which the transfer is performed moves to the discharge side D at any time while contacting the claw portion 18b. At this time, the transfer paper 16 is charged by the transfer bias, but is discharged by coming into contact with the claw portion 18B formed on the contacting / separating member 183 which is formed of a conductive member and grounded. Therefore, it is not necessary to collect and install the static eliminator of the transfer paper 16, which contributes to cost reduction and space saving.

Asperities 18 are formed on the upper surfaces of the claws 18A and 18B.
Since C is formed, the friction with the transfer paper 16 increases, and the slip of the transfer paper 16 on the claw portions 18A and 18B can be prevented. Therefore, the contact / separation member 183 can be stably pressed to the discharge side D even with a weak pressing force due to the moving force of the transfer paper 16 or the frictional force between the transfer paper 16 and the claw portions 18A and 18B.
As a result, the cylindrical thin film member 182 is stably pushed up toward the photoconductor 1 by the protrusion A. Therefore, the transfer paper 16 can be stably brought into contact with the photoconductor 1, which leads to stable transfer.

When the transfer paper 16 has finished passing through the transfer section B,
The pressing force exerted on the claw portions 18A and 18B by the transfer paper 16, that is, the urging force of the transfer paper 16 toward the downstream side D disappears. Then, the contact / separation member 183 swings from the transfer position shown in FIG. 3 toward the approaching side C by its own weight, contacts the stopper 184, and is held at the transfer paper receiving position. By swinging the contacting / separating member 183, the cylindrical thin film member 182 and the protrusion A
Are separated from each other, and the tubular thin film member 182 pushed up toward the photoconductor 1 is placed in an initial state separated from the photoconductor 1 and is in a standby state for the next transfer sheet. Since the tubular thin film member 182 placed in the initial state is separated from the photoconductor 1, residual toner or the like remaining on the photoconductor does not adhere, and the inside of the transfer device 18 and its periphery do not become dirty.

In the transfer device 18 described above, the transfer roller 181 may be rotatably supported or may be fixed. When the transfer roller 181 is rotatably supported, the cylindrical thin film member 1 mounted on the transfer roller 181 is mounted.
It is preferable to set the speed so that the linear speeds of 82 and the photoconductor 1 rotate at the same speed. Further, although the transfer paper 16 has been described as an example of the transfer member, a film or the like used in an overhead projector (OHP) or the like may be used instead. Further, here, the claw portions 18A, 1
The uneven portion 18C is provided as a frictional resistance portion on 8B to increase the resistance to the moving transfer paper 16, but in addition to this,
The upper surfaces of the claw portions 18A and 18B are roughened like sandpaper, or the transfer paper 16 such as a rubber member or a cork material is used.
It is also possible to provide a member that increases the contact resistance with. In short, it is important that the transfer member to be fed does not slip on the claw portions 18A and 18B, and it is preferable to provide a frictional resistance portion corresponding to the transfer member on the claw portions 18A and 18B (particularly the claw portion 18A).

In the present embodiment, the transfer roller 181 and the tubular thin film member 1 having a length substantially the same as the width of the photoconductor 1 in the axial direction.
82 is used, as another example, a plurality of transfer rollers and tubular thin film members formed shorter than the width of the photoconductor 1 are arranged in the axial direction of the photoconductor 1, and the transfer roller and the tubular The tubular thin film member is moved up and down by one contacting / separating member having a plurality of projections corresponding to the number of thin film members, or
The contacting / separating member is arranged so as to correspond to each transfer roller and the cylindrical thin film member, and the cylindrical thin film member 182 is arranged by each contacting / separating member.
It may be configured to move up and down.

[0022]

According to the present invention, since the tubular thin film member loosely fitted to the support member to which the transfer voltage is applied comes into contact with the image carrier, the tubular thin film member is deformed at the time of contact and the contact pressure is applied. Since it is possible to uniformly transfer to the transfer member and the cylindrical thin film member is deformed when it comes into contact, even if the thickness of the transfer member varies, the deformation can be tolerated and special clearance management is required. The transfer device can cope with a wide transfer member without doing so. Further, since the cylindrical thin film member is separated from the image carrier during non-transfer, the adhesion of toner remaining on the image carrier to the cylindrical thin film member is reduced, and a clean transfer device is provided. Can be provided. Further, the contacting / separating member is operated by a weak force such as a conveyance force of the transfer member or a frictional force between the transfer member and the claw portion, and the transfer member is sandwiched between the image carrier and the tubular thin film member. While performing the transfer operation,
Since the contacting / separating member is made of a conductive member and is grounded, there is no need for driving means such as an electromagnetic actuator or a charge removing device for the transfer member, and the structure of the device can be simplified and a low-cost transfer device is provided. can do. That is, according to the present invention, the cylindrical thin film member can be brought into and out of contact with the photoconductor by the rigidity and the moving force caused by the slack of the transfer member in synchronism with the entry of the transfer member. It is possible to achieve the object of preventing the transfer device from being contaminated by the toner remaining on the transfer device and providing a transfer device having a small number of parts and a simple structure at a low cost.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus in which a transfer device of the present invention is adopted.

FIG. 2 is a side view showing a schematic configuration showing an embodiment of a transfer device of the present invention and a state of the device when not transferring.

FIG. 3 is a side view showing a state of the transfer device during transfer.

FIG. 4 is an enlarged view of a claw portion of a contacting / separating member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image carrier (photoreceptor) 16 Transfer member 18 Transfer device 18A, 18B Claw part 18C Friction resistance part 8 uneven part 181 Support member (transfer roller) 182 Cylindrical thin film member 183 Contact / separation member B Transfer part C Transfer member Entry side D Transfer member discharge side E Entry path F Discharge path F, E Transfer member path

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasushi Nakazato 1-3-6 Nakamagome, Ota-ku, Tokyo, Ricoh Co., Ltd. (72) Inventor Satoshi Muramatsu 1-3-6 Nakamagome, Ota-ku, Tokyo No./In stock company Ricoh (72) Inventor Yoshiko Ishii 1-3-6 Nakamagome, Ota-ku, Tokyo-Inside Ricoh company (72) Nobuto Yokokawa 1-3-6 Nakamagome, Ota-ku, Tokyo- In Ricoh Co., Ltd. (72) Inventor Masako Suzuki 1-3-6 Nakamagome, Ota-ku, Tokyo ・ In Ricoh Co., Ltd.

Claims (7)

[Claims] 1. An electrophotographic apparatus for transferring a toner image formed on an image carrier to a transfer member by using a transfer device, and a support member facing the image carrier and to which a transfer voltage is applied. A cylindrical thin film member having a peripheral length slightly longer than the peripheral length of the supporting member and loosely fitted to the supporting member, and moving in a direction of bringing the cylindrical thin film member into contact with and separating from the image carrier. A transfer device, comprising: 2. At least one or a plurality of the contacting / separating members are disposed on the entrance side and the discharge side of the transfer member with a transfer portion formed between the image carrier and the cylindrical thin film member being sandwiched therebetween. The transfer device according to claim 1, wherein 3. The contacting / separating member has a claw portion that extends toward the entrance side of the transfer member and the discharge side of the transfer member with the transfer portion interposed therebetween, and the claw portion is on the entrance path of the transfer member. The transfer device according to claim 1, wherein the transfer device faces the transfer device. 4. The transfer device according to claim 1, 2 or 3, wherein the contacting / separating member is formed of a conductive member. 5. The transfer device according to claim 4, wherein the contacting / separating member is grounded. 6. A tubular member, wherein the contacting / separating member is swingable, and is placed in an initial state in which the contacting / separating member is pushed by the transfer member as the transfer member enters the transfer portion and is separated from the image carrier. The direction in which the thin film member is pushed up toward the image carrier and the transfer member is sandwiched between the image carrier and the pushing direction of the tubular thin film member is released when the transfer member finishes passing through the transfer section. The transfer device according to claim 1, 2 or 3, wherein the transfer device swings in a direction of rotation. 7. The transfer device according to claim 3, wherein a frictional resistance portion is provided at a contact portion of the claw portion with the transfer member.