JP2015087440A - Transfer device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the contamination of a sheet with toner in a lateral conveyance type transfer device.SOLUTION: A transfer device 10 includes a transfer roller 15 provided so as to come into contact with a photoreceptor drum 31 and form a nip part N and conveying a sheet 4 in a lateral direction along a horizontal direction in the nip part N, a first guide member 16 arranged to face the front side surface of the sheet 4, a second guide member 17 arranged to face the rear side surface of the sheet 4, and a cover member 40 covering a gap between the sheet 4 and the end on the side of the nip part N of the first guide member 16, in a state where the sheet 4 is pressed from the side of the first guide member 16 and is in contact with the second guide member 17.

Description

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

  For example, an image forming apparatus such as a laser printer or a multifunction peripheral includes a transfer device that transfers a toner image formed on a photosensitive drum onto a sheet such as paper. The transfer device generally has a transfer roller that forms a nip portion in contact with the photosensitive drum, and a bias voltage having a polarity opposite to the polarity of the toner is applied from the back surface of the sheet at the nip portion. As a result, the toner image is transferred from the photosensitive drum to the printing surface of the sheet for transfer.

  Japanese Patent Application Laid-Open No. 2004-228561 describes a transfer device that transports a sheet in a vertical direction (hereinafter referred to as a vertical transport system) at a nip portion formed by a transfer roller and a photosensitive drum. The transfer device includes a paper guide that guides the paper upward toward the nip portion. The paper guide has a paper front side member and a paper back side member facing each other.

  Further, the transfer device includes a flexible sheet made of a polyester film having a lower end fixed to the paper front side member and an upper end contacting the paper back side member, the flexible sheet and the paper back side member, The paper passes between them. As a result, the toner scattered from the photosensitive drum is shielded by the flexible sheet, and the paper surface is prevented from being contaminated by the toner.

  Here, a transfer device that transports a sheet of paper or the like in the lateral direction along the horizontal direction at the nip portion (hereinafter referred to as a lateral transport method) is also generally known. Since the horizontal transfer type transfer device can easily save space in the apparatus, the horizontal transfer method is preferable to the vertical transfer method from the viewpoint of downsizing the apparatus.

Japanese Patent Application Laid-Open No. 8-211753

  Therefore, it is conceivable to apply the configuration of the vertical conveyance method described in Patent Document 1 to a transfer device of the horizontal conveyance method. By the way, in the transfer device of Patent Document 1, the gap between the flexible sheet and the sheet surface side member is a concave toner collecting portion that collects toner. When the configuration of Patent Document 1 is applied to the lateral conveyance system as it is, the toner collecting unit is disposed so as to be opened to the side, so that the toner that has entered the toner collecting unit is, for example, that of a photosensitive drum. It becomes easy to wind up by the wind produced by rotation etc. Therefore, there is a possibility that the paper is soiled by the rolled up toner.

  The present invention has been made in view of the above points, and an object of the present invention is to suppress contamination of a sheet by toner in a lateral conveyance type transfer device.

  The transfer device according to the present invention is provided so as to form a nip portion in contact with the photosensitive drum, and the sheet is conveyed to the outer peripheral surface of the photosensitive drum while being conveyed in the horizontal direction along the horizontal direction at the nip portion. A transfer roller that transfers the formed toner image to the sheet, and a first guide that is disposed to face the front side of the sheet on which the toner image is transferred and guides the sheet to the nip portion. A member, a second guide member that is disposed opposite to the back side of the sheet opposite to the front side, and that guides the sheet to the nip portion; and is provided on the first guide member, the first guide In a state where the sheet passing between the member and the second guide member is pressed from the first guide member side and brought into contact with the second guide member, the sheet and the first guide portion And a cover member for covering the space between the ends of the nip portion side in.

  According to the present invention, it is possible to suppress the contamination of the sheet by the toner in the lateral transfer type transfer device.

FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus according to the present embodiment. FIG. 2 is a side view showing a schematic configuration of the transfer apparatus according to the first embodiment. FIG. 3 is a perspective view showing an appearance of the first guide member. FIG. 4 is a perspective view showing the appearance of the cover member. FIG. 5 is an enlarged side view showing the vicinity of the cover member. FIG. 6 is an enlarged side view showing the end portion on the nip portion side of the first guide member. FIG. 7 is a side view showing a schematic configuration of the transfer apparatus according to the second embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiment.
Embodiment 1

  FIG. 1 is a cross-sectional view illustrating a schematic structure of the image forming apparatus 1. The image forming apparatus 1 is, for example, a printer, and includes a transfer device 10, a fixing unit 11, an optical scanning unit 12, and an image forming unit 13, as shown in FIG.

  A paper feed cassette 3 is disposed below the inside of the main body 2 of the image forming apparatus 1. The paper feed cassette 3 stores and accommodates sheets 4 as sheets before printing inside. A first paper transport unit 21 is provided on the side of the paper feed cassette 3. The first paper transport unit 21 receives the paper fed from the paper feed cassette 3 and transports the paper upward.

  A manual paper feed unit 5 is provided on the right side of the paper feed cassette 3. A second paper transport unit 22 is provided on the left side of the manual paper feed unit 5. The second paper transport unit 22 transports the paper fed from the manual paper feed unit 5 or the paper transported from the first paper transport unit 21 to the side image forming unit 13. The second paper transport unit 22 is provided with a registration roller 26 for feeding the paper 4 to the image forming unit 13 at a predetermined timing.

  The optical scanning unit 12 is disposed above the second paper transport unit 22 and includes a light source (not shown) such as a laser diode and a polygon mirror (not shown) that reflects light from the light source. The image forming apparatus 1 is configured to irradiate the image forming unit 13 with laser light based on the image data received.

  The image forming unit 13 includes a photoconductor drum 31 that is a photoconductor, and a charger 32, a developing device 33, and a cleaning device 34 disposed around the photoconductor drum 31.

  The photosensitive drum 31 is rotationally driven by a drive motor (not shown). The charger 32 uniformly charges the outer peripheral surface of the photosensitive drum 31 to a predetermined potential by a charging bias applied from a charging bias power source (not shown). The photosensitive drum 31 is formed with an electrostatic latent image by writing light emitted from the optical scanning unit 12.

  The developing device 33 has a developing roller 35 that stores toner and rotates in contact with the photosensitive drum 31. The developing device 33 attaches toner to the electrostatic latent image on the photosensitive drum 31 by the developing roller 35. Then, the electrostatic latent image on the photosensitive drum 31 is developed and visualized as a toner image. After the toner image is transferred from the photosensitive drum 31 to the paper, the cleaning device 34 cleans the outer peripheral surface of the photosensitive drum 31 and removes residual toner and foreign matters from the outer peripheral surface.

  Here, FIG. 2 shows an enlarged schematic configuration of the transfer apparatus. The transfer device 10 is disposed below the image forming unit 13 and includes a transfer roller 15, a first guide member 16, and a second guide member 17, as shown in FIG.

  The transfer roller 15 is provided so as to form the nip portion N in contact with the photosensitive drum 31. The transfer roller 15 transfers the toner image formed on the outer peripheral surface of the photosensitive drum 31 to the sheet 4 while conveying the sheet 4 in the horizontal direction along the horizontal direction at the nip portion N.

  Here, FIG. 3 shows an appearance of the first guide member 16. As shown in FIGS. 2 and 3, the first guide member 16 is disposed so as to face the front side surface on which the toner image on the paper 4 is transferred, and guides the paper 4 to the nip portion N. As for the 1st guide member 16, the lower surface which contacts the paper 4 is curving concavely. The first guide member 16 is made of a conductive material such as metal, for example.

  On the other hand, the second guide member 17 is arranged to face the back side surface opposite to the front side surface of the paper 4 and guides the paper 4 to the nip portion N. The second guide member 17 is disposed to face the end portion on the nip portion N side of the first guide member 16.

  In addition, the transfer device 10 includes a transport plate 18 disposed to face the first guide member 16. An end portion on the nip portion N side of the transport plate 18 is in contact with the second guide member 17. The first guide member 16, the second guide member 17, and the transport plate 18 are disposed between the nip portion N and the registration roller 26.

  The fixing unit 11 is provided on the side of the image forming unit 13. Between the image forming unit 13 and the fixing unit 11, a third paper transport unit 23 that transports the paper 4 to which the toner image is transferred to the fixing unit 11 is formed. The fixing unit 11 includes a fixing roller 27 and a pressure roller 28 that rotate. The toner image is fixed on the paper 4 by heating and pressing the paper 4 with the fixing roller 27 and the pressure roller 28.

  Formed on the upper portion of the main body 2 is a paper discharge portion 29 for discharging the paper 4 on which the toner image is fixed. A fourth paper transport unit 24 is formed between the fixing unit 11 and the paper discharge unit 29. A control unit 30 that controls an image forming process in the image forming apparatus 1 is provided above the fixing unit 11.

  As described above, in the image forming apparatus 1, an electrostatic latent image is formed on the photosensitive drum 31 by the optical scanning unit 12 optically scanning the photosensitive drum 31 based on the image data. Thereafter, the electrostatic latent image on the photosensitive drum 31 is developed as a toner image by the developing device. Next, the toner image on the photosensitive drum 31 is transferred to the paper 4 conveyed from the first paper conveyance unit 21 by the transfer device 10. Thereafter, the sheet 4 on which the toner image is fixed by the fixing unit 11 is discharged to the sheet discharge unit 29.

  The transfer device 10 includes a cover member 40 provided on the first guide member 16. The cover member 40 is configured by a flexible sheet having elasticity such as PET. The cover member 40 is made of a material that is charged with the same polarity as the toner.

  Here, FIG. 4 shows the appearance of the cover member 40. FIG. 5 shows the vicinity of the cover member 40 in an enlarged manner. FIG. 6 is an enlarged view of the end portion on the nip portion N side of the first guide member 16.

  As shown in FIGS. 4 and 5, the cover member 40 includes a rectangular sheet-like first portion 41 and a first portion 41 bent from the end on the nip portion N side to the first guide member 16 side. And a third portion 43 extending from the end of the first portion 41 opposite to the second portion 42 along the first guide member 16 to the opposite side of the nip portion N.

  The 3rd part 43 is affixed on the surface facing the paper 4 in the 1st guide member 16 via a double-sided adhesive tape (not shown), for example. As a result, in the cover member 40, the front end A, which is the nip portion N side portion of the first portion 41, urges the paper 4 toward the second guide member 17 and the first guide member 16 and the second guide member. 17 can be swung between. In addition, you may use an adhesive agent instead of a double-sided adhesive tape.

  A plurality of slits 44 extending from the proximal end side to the distal end side of the second portion 42 are formed in the second portion 42. The slit 44 is inserted with a guide pin 45 projecting from an end 16 a on the nip portion N side of the first guide member 16. The distal end of the guide pin 45 is connected to a plate-like stopper portion 46 extending along the front end of the first guide member 16. The stopper portion 46 is provided so as to cover the slit 44. Thus, the second portion 42 can swing when the guide pin 45 is guided by the slit 44.

  In this manner, the cover member 40 is in a state where the sheet 4 passing between the first guide member 16 and the second guide member 17 is pressed from the first guide member 16 side and brought into contact with the second guide member 17. Thus, the second portion 42 covers the space between the sheet 4 and the end portion 16 a of the first guide member 16.

  Accordingly, the sheet 4 supplied from the registration roller 26 to the transfer device 10 is guided by the first guide member 16 and the transport plate 18, and the front end thereof contacts the cover member 40. The sheet 4 is guided by the second guide member 17 while its front side is pressed by the cover member 40. Thus, the sheet 4 is conveyed toward the nip portion N while being sandwiched between the front end portion A of the cover member 40 and the second guide member 17.

  As described above, in the present embodiment, by providing the cover member 40 on the first guide member 16, the sheet 4 passing between the first guide member 16 and the second guide member 17 is transferred to the first guide member 16. Since the space between the sheet 4 and the end portion 16a of the first guide member 16 is covered with the second guide member 17 pressed from the side, the first guide member 16 and the second guide member 17 Can be closed together with the paper 4 by the cover member 40. Therefore, since the toner scattered from the developing roller 35 and the photosensitive drum 31 can be prevented from entering between the first guide member 16 and the second guide member 17, the sheet of toner using the lateral transfer type transfer device 10 can be suppressed. 4 can be suitably suppressed.

  Furthermore, since the cover member 40 is formed of a flexible sheet, the paper 4 can be urged toward the second guide member 17 with a simple configuration. Furthermore, since the cover member 40 is made of a material that is charged with the same polarity as the toner, even when the cover member 40 is charged by friction with the paper 4, toner adhesion to the cover member 40 can be prevented.

  Furthermore, since the front end portion A of the cover member 40 is configured to be swingable, the cover member 40 and the second guide member 17 sandwich the sheet 4 even when the sheet 4 is relatively thick. The paper 4 can be suitably conveyed.

In addition, since the first guide member 16 is made of a conductive material, toner scattering due to static electricity generated by friction between the first guide member 16 and the paper 4 can be prevented. Therefore, the disturbance of the image formed on the paper 4 can be suppressed.
<< Embodiment 2 >>

  FIG. 7 shows a schematic configuration of the transfer apparatus according to the second embodiment. In the first embodiment, the example in which the cover member 40 is fixed to the first guide member 16 by the double-sided adhesive tape in the third portion 43 has been described, but may be fixed by the fixing member 50 as shown in FIG.

  That is, the cover member 40 is fixed by the fixing member 50 on the surface of the first guide member 16 on the side facing the paper 4 in the third portion 43. The fixing member 50 is configured to guide the front end of the paper 4 to a position where the paper 4 pressed by the cover member 40 contacts the second guide member 17.

  The fixing member 50 is made of a conductive material such as metal. As a result, scattering of toner due to static electricity generated by friction between the fixing member 50 and the paper 4 can be prevented. Note that the fixing member 50 may be formed of other materials such as polycarbonate.

  Therefore, also in this embodiment, since the cover member 40 is provided in the transfer device 10, the same effect as in the first embodiment can be obtained. In addition, while the cover member 40 is appropriately fixed to the first guide member 16 by the fixing member 50, the paper 4 supplied from the registration roller 26 is suitably guided by the fixing member 50 to stabilize the paper 4. Can be transported.

  In the first and second embodiments, the example in which the cover member 40 is formed of a flexible sheet has been described. However, the present invention is not limited to this. You may make it urge.

  In the above-described embodiment, the printer is described as an example of the image forming apparatus. However, the image forming apparatus is not limited thereto, and may be another image forming apparatus such as a copying machine, a scanner device, or a multifunction peripheral.

  As described above, the present invention is useful for a transfer device and an image forming apparatus.

1 Image forming apparatus 4 Paper (sheet)
DESCRIPTION OF SYMBOLS 10 Transfer apparatus 15 Transfer roller 16 1st guide member 17 2nd guide member 31 Photosensitive drum 40 Cover member 50 Fixing member

Claims (5)

The toner image formed on the outer peripheral surface of the photosensitive drum is provided so as to form a nip portion in contact with the photosensitive drum, and the sheet is conveyed in the lateral direction along the horizontal direction in the nip portion. A transfer roller for transferring to the sheet;
A first guide member that is disposed to face a front side of the sheet on which the toner image is transferred and guides the sheet to the nip portion;
A second guide member disposed opposite to the back side opposite to the front side of the sheet and guiding the sheet to the nip portion;
In a state where the sheet that is provided on the first guide member and passes between the first guide member and the second guide member is pressed from the first guide member side and is in contact with the second guide member. And a cover member that covers a space between the sheet and the end portion on the nip portion side of the first guide member. The transfer device according to claim 1,
The transfer device, wherein the cover member is constituted by a flexible sheet. The transfer device according to claim 1.
The transfer device, wherein the cover member is made of a material that is charged to the same polarity as the toner. The transfer device according to claim 1.
The cover member is fixed by a fixing member on the surface of the first guide member on the side facing the sheet,
The transfer device, wherein the fixing member is configured to guide the front end of the sheet to a position where the sheet pressed by the cover member contacts the second guide member. A photosensitive drum;
A toner image formed on the outer peripheral surface of the photosensitive drum is provided so as to form a nip portion in contact with the photosensitive drum, and the sheet is conveyed in the lateral direction along the horizontal direction in the nip portion. A transfer roller for transferring to the sheet;
A first guide member that is disposed to face a front side of the sheet on which the toner image is transferred and guides the sheet to the nip portion;
A second guide member disposed opposite to the back side opposite to the front side of the sheet and guiding the sheet to the nip portion;
In a state where the sheet that is provided on the first guide member and passes between the first guide member and the second guide member is pressed from the first guide member side and is in contact with the second guide member. An image forming apparatus comprising: a cover member that covers a space between the sheet and the end portion on the nip portion side of the first guide member.

Images