Transfer apparatus and image forming apparatus

Abstract

To provide a transfer device that can remove untransferred toner attached to a conveyance guide on the upstream side of a transfer unit in a small space at low cost, and can be mounted in a small-sized apparatus.SOLUTION: A transfer device has an image carrier 102 on which a toner image is formed, a transfer unit 112 that is arranged opposite to the image carrier 102 and transfers the toner image to a sheet P, and a guide member 130 that is arranged on the upstream side in a sheet conveyance direction of the transfer unit 112. In conjunction with the rotation of the transfer unit, the guide member 130 vibrates in a direction to separate from the transfer unit 112 or a direction to approach the transfer unit.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a transfer device and an image forming apparatus.

Background Art

[0002] In a transfer device of an electrophotographic image forming apparatus, a conveyance guide for guiding a sheet to a transfer unit formed by a transfer device such as a transfer roller facing an image carrier is provided upstream of the transfer device. In order to stabilize the posture of the sheet entering the transfer unit, the gap between the conveyance guide and the image carrier is set to a narrow interval. Untransferred toner scattered from background stains or image density adjustment patches on the image carrier adheres to the conveyance guide and causes contamination, resulting in problems such as soiling the leading edge or back surface of the sheet during printing. Therefore, techniques for periodically cleaning manually, separating the transfer device from the image carrier during non-printing, or applying an alternating voltage to the conveyance guide to remove the untransferred toner adhering to the conveyance guide are already known.

[0003] In a conventional transfer device, a high-voltage power source for applying an alternating voltage to the conveyance guide and a space for securing a path from the high-voltage power source to the conveyance guide were required, resulting in an increase in the size of the device and an increase in cost.

[0004] Patent Document 1 discloses a transfer device that applies an alternating voltage to a conveyance guide using a high-voltage power source to remove untransferred toner adhering to the conveyance guide located upstream of the transfer device and electrically controls the charging polarity of the untransferred toner. However, due to the increase in the size of the device, it is not possible to remove the untransferred toner adhering to the conveyance guide with space savings and low cost. Further, such a transfer device cannot be mounted on a small device.

Summary of the Invention

Problems to be Solved by the Invention

[0005] Therefore, an object of the present invention is to provide a transfer device that can remove untransferred toner adhering to a guide member on the upstream side in the sheet conveyance direction of a transfer device with space savings and low cost and can be mounted on a small device. [Means for solving the problem]

[0006] This problem involves an image carrier on which a toner image is formed, a transfer unit positioned opposite the image carrier for transferring the toner image to paper, and a guide member positioned upstream of the transfer unit in the paper transport direction for guiding the paper. Without changing the positional relationship between the image carrier and the transfer device from the positional relationship during paper feeding, The transfer device In the opposite direction to when the paper is being fed through. The problem is solved by a transfer device characterized in that the guide member vibrates in a direction away from or toward the transfer device in conjunction with the rotation of the transfer device. [Effects of the Invention]

[0007] This enables the removal of untransferred toner adhering to the guide member on the upstream side of the paper transport direction of the transfer unit in a space-saving and low-cost manner, resulting in a transfer device that can be installed in small equipment. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows the overall configuration of an image forming apparatus according to one embodiment of the present invention. [Figure 2] This figure shows the configuration of a transfer device according to one embodiment of the present invention. [Figure 3] This figure shows the operation of a transfer device according to one embodiment of the present invention during image density adjustment. [Figure 4] This figure shows the operation of a transfer apparatus according to one embodiment of the present invention during printing. [Modes for carrying out the invention]

[0009] Figure 1 shows the overall configuration of an image forming apparatus according to one embodiment of the present invention. This image forming apparatus is a typical monochrome image forming apparatus. A black process cartridge 101 is detachably mounted on the main body 100 of the image forming apparatus, and the main body 100 contains an exposure unit 104, a transfer unit 120, a paper feed tray 121, a fuser unit 140, and the like.

[0010] During single-sided printing, a latent image is formed on the photoreceptor 102, which acts as an image carrier, by the exposure device 104, a toner image is created in the process cartridge 101, and the process moves to the transfer step. The paper P held in the paper feed tray 121 is transported by the paper feed roller 122 to the registration roller pair 123, where the amount of paper P fed out is adjusted by the registration roller pair 123 so that the leading edge of the paper P aligns with the toner image at the nip position (transfer nip) between the photoreceptor 102 and the transfer roller 112, and a transfer bias is applied to the transfer roller 112 to transfer the toner image to the paper P. Since the paper P that has passed through the transfer nip is charged by the transfer bias, it is separated from the photoreceptor 102 or the transfer roller 112 by the static elimination needle 113. Next, the paper P is transported to the fuser device 140, where the transferred toner image is fused to the paper P by heat and pressure, and the paper is discharged to the outside paper tray 125 by the paper discharge roller 124.

[0011] During double-sided printing, the position of the separation claw 126 located upstream of the paper output roller 124 is switched, the reversing roller 127 is rotated in the reverse direction to feed the paper P into the reversing pass 128, the separation claw 126 is returned to its original position, and the paper output roller 124 is rotated forward to feed the paper P into the double-sided pass 129. The paper P transported to the double-sided pass 129 is then transported back to the registration roller pair 123, and thereafter the second side is printed using the same process as single-sided printing.

[0012] Figure 2 shows the configuration of a transfer apparatus according to one embodiment of the present invention. The transfer device 120 in this embodiment includes a photoreceptor 102 as an image carrier on which a toner image is formed, and a transfer roller 112 positioned opposite the photoreceptor 102 and transferring the toner image to the paper P. The transfer device 120 also includes a guide member 130 positioned adjacent to the transfer roller 112 on the upstream side in the paper transport direction, opposite the photoreceptor 102. In the transfer device 120 having such a configuration, the guide member 130 can vibrate or rotate around a pivot point 130A in a direction away from or toward the transfer roller 112 in conjunction with the rotation of the transfer roller 112. The vibration of the guide member 130 peels off and removes any dirt adhering to the guide member 130. This provides a transfer device 120 for an electrophotographic image forming apparatus that can remove untransferred toner adhering to the guide member 130 upstream of the transfer roller 112 in a space-saving and low-cost manner, and can also be mounted in a small device.

[0013] The guide member 130 has a guide portion that guides the paper P near the transfer roller 112 with respect to the pivot point 130A. On the side opposite the guide portion with respect to the pivot point 130A, the guide member 130 is biased by a spring 131 to rotate toward the transfer roller 112, while on the side of the guide portion, it is stopped from rotating by a positioning pin 133 so as not to come into contact with the transfer roller 112. The positioning pin 133 is a restricting means that regulates the distance of the guide member 130 from the transfer roller 112, and the spring 131 is a biasing means that biases the guide member 130 toward the transfer roller 112. During printing, the guide member 130 is in a position to contact the positioning pin 133. In addition, the vibration amplitude of the guide member 130 is set to a width that prevents the guide member 130 from coming into contact with the photoreceptor 102.

[0014] Furthermore, projections 130B extending toward the transfer roller 112 are provided at both longitudinal ends of the guide portion of the guide member 130 (i.e., the front and back sides of the paper). A ratchet wheel (claw member) 135, which acts as a vibrating member, is provided on the shaft 112A of the transfer roller 112 opposite the projections 130B, via a one-way clutch 137. The ratchet wheel 135 has multiple claw portions 135A in a plane perpendicular to the shaft 112A of the transfer roller 112. The rotational diameter of the claw portions 135A of the ratchet wheel 135 or the rotational diameter of the tip of the ratchet wheel 135 is at a height that contacts the projections 130B of the guide member 130 when it rotates toward the transfer roller 112, and is smaller than the outer diameter of the transfer roller 112. The one-way clutch 137 is set so that the claw wheel 135 rotates only when the transfer roller 112 rotates counterclockwise, in the opposite direction to when paper is being fed, as shown in the figure.

[0015] As shown in Figure 2, when the photoreceptor 102 is rotated clockwise during non-image formation, the transfer roller 112 rotates counterclockwise along with the photoreceptor 102, and the ratchet wheel 135 also rotates counterclockwise due to the action of the one-way clutch 137. As a result, the rotation of the ratchet wheel 135 causes the ratchet wheel 135A to come into contact with and separate from the projection 130B of the guide member 130, causing the guide member 130 to vibrate around the pivot point 130A, thereby peeling off and removing any untransferred toner adhering to the guide member 130.

[0016] Then, the untransferred toner removed by the vibration of the guide member 130 is attracted to the photoreceptor 102 by electrostatic force and recovered by the cleaning member provided on the photoreceptor 102.

[0017] Figure 3 shows the operation of a transfer device according to one embodiment of the present invention during image density adjustment. As shown in the figure, during image density adjustment, part of the adjustment patch formed on the photoreceptor 102 may scatter as untransferred toner and adhere to the tip of the guide member 130. At this time, the photoreceptor 102 rotates counterclockwise as shown in the figure, and the transfer roller 112 rotates clockwise following this, but the claw wheel 135 idles due to the action of the one-way clutch 137 and does not rotate. Therefore, the claw portion 135A of the claw wheel 135 does not contact the protrusion 130B of the guide member 130, and the guide member 130 is at the position where it contacts the positioning pin 133 and does not vibrate.

[0018] FIG. 4 is a diagram showing the operation during printing of a transfer device according to an embodiment of the present invention. Most of the toner image formed on the photoreceptor 102 is transferred to the surface of the paper P at the transfer nip, but the background dirt toner on the photoreceptor 102 may scatter during power-on initialization or between papers and adhere to the tip of the guide member 130. Then, as shown in the figure, during printing, the untransferred toner adhering to the tip of the guide member 130 may adhere to the back surface of the paper P guided by the guide member 130, and the paper P may become dirty. At this time, the photoreceptor 102 rotates counterclockwise as shown in the figure, and the transfer roller 112 rotates clockwise following this, but the claw wheel 135 idles due to the action of the one-way clutch 137 and does not rotate. Therefore, the claw portion 135A of the claw wheel 135 does not contact the protrusion 130B of the guide member 130, and the guide member 130 is at the position where it contacts the positioning pin 133 and does not vibrate.

[0019] Aspects of the present invention are as follows, for example. <1> An image carrier on which a toner image is formed, A transfer device disposed opposite to the image carrier for transferring the toner image to paper, A guide member disposed upstream in the paper conveyance direction of the transfer device for guiding the paper, and having A transfer device characterized in that the guide member vibrates in a direction away from or toward the transfer device in conjunction with the rotation of the transfer device. <2> Protrusions are provided at the longitudinal ends of the guide member, On the axis of the transferrer facing the protrusion, a vibration member having a surface with uneven shape and capable of contacting the protrusion is arranged. The transfer device according to <1> above, wherein the guide member vibrates due to contact or separation between the protrusion of the guide member and the vibration member of the transferrer. <3> The transfer device according to <2> above, wherein the vibration member has a claw member having a plurality of claw portions, the rotation diameter of the claw member has a height that contacts the protrusion of the guide member, and is smaller than the outer diameter of the transferrer. <4> The vibration member is provided on the axis of the transferrer via a one-way clutch. The transfer device according to <2> or <3> above, wherein the vibration member also rotates only when the transferrer rotates in the direction opposite to the paper passing direction by the one-way clutch. <5> The transfer device according to any one of <1> to <4> above, wherein the vibration amplitude of the guide member is set to a width such that the guide member does not hit the image carrier. <6> Regulation means for regulating the distance between the guide member and the transferrer, and The transfer device according to any one of <1> to <5> above, which has biasing means for biasing the guide member toward the transferrer. <7> The transfer device according to any one of <1> to <6> above, wherein the untransferred toner removed by the vibration of the guide member is attached to and recovered by the image carrier. <8> An image forming apparatus having the transfer device according to any one of <1> to <7> above.

Explanation of Signs

[0020] 102 Photoconductor (image carrier) 112 Transfer roller (transferrer) 130 Guide member 130B Protrusion 131 Spring (biasing means) 133 Positioning pin (regulation means) 135 Claw wheel (vibration member, claw member) 135A Claw portion 137 One-way clutch P paper [Preliminary Technology Documents] [License]

[0021] [License 1] Special Announcement No. 07-306600

Claims

1. Image carrier on which toner image is formed, A transfer device positioned opposite the image carrier, which transfers the toner image onto the paper. The transfer unit has a guide member positioned upstream in the paper transport direction, which guides the paper. A transfer apparatus characterized in that, without changing the positional relationship between the image carrier and the transfer device from the positional relationship during paper feeding, the guide member vibrates in a direction away from or toward the transfer device in conjunction with the rotation of the transfer device in the opposite direction to the rotation during paper feeding.

2. A projection is provided at the longitudinal end of the guide member, A vibrating member having an uneven surface that can contact the projection is positioned on the shaft of the transfer device facing the projection. The transfer apparatus according to claim 1, characterized in that the guide member vibrates due to contact or separation between the projection of the guide member and the vibrating member of the transfer device.

3. The transfer apparatus according to claim 2, wherein the vibrating member has a claw member having a plurality of claw portions, and the rotational diameter of the claw member has a height that contacts the projection of the guide member and is smaller than the outer diameter of the transfer device.

4. The vibrating member is provided on the shaft of the transfer device via a one-way clutch. The transfer apparatus according to claim 2 or 3, characterized in that the one-way clutch causes the vibrating member to rotate only when the transfer device rotates in the opposite direction to when paper is being fed.

5. The transfer apparatus according to any one of claims 1 to 3, characterized in that the vibration amplitude of the guide member is set to a width such that the guide member does not come into contact with the image carrier.

6. A restricting means for restricting the distance of the guide member from the transfer device, and The transfer apparatus according to any one of claims 1 to 3, characterized in that it has a biasing means for biasing the guide member toward the transfer device.

7. The transfer apparatus according to any one of claims 1 to 3, characterized in that the untransferred toner removed by the vibration of the guide member is attached to the image carrier and recovered.

8. An image forming apparatus having a transfer apparatus according to any one of claims 1 to 3.

Images