JP2008110843A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device having a double-sided printing function, capable of forming a high-quality image, by effectively removing electric charge the paper receives from a roller. <P>SOLUTION: This image forming device 1 has static eliminating brushes 13 and 14 being a static eliminating member having substantially the same length as a width of a paper feeding carrier roller 5 in the paper width direction, in the vicinity of the paper feeding carrier roller 5 rotating by contacting with the paper on a paper feeding-paper carrying passage 4. The static eliminating brushes 13 and 14 are arranged so as to contact with the paper in a place corresponding to a locus of the paper feeding carrier roller 5 extended in the paper carrying direction. As a result, the electric charge received from the roller to the paper can be effectively removed by the static 3 eliminating brushes 13 and 14 arranged in a proper place. The paper can be particularly further effectively statically eliminated in double-sided printing further easily electrified differently from when printing only one side. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus represented by a copying machine or a printer.

  In an electrophotographic image forming apparatus such as a copying machine or a printer, an image forming unit (image forming unit) that forms a toner image on the surface of a photosensitive member, a transfer unit that transfers the toner image to a sheet, Components such as a fixing unit for fixing the toner image are provided. The sheet is conveyed along the sheet conveyance path between the components including these. In the sheet conveyance path, a conveyance guide member constituting the path, a conveyance roller for feeding the sheet, a conveyance roller, and a movable guide for switching the conveyance direction are arranged.

  Here, the sheet may be charged due to charge accumulation due to transfer of the toner image at the transfer unit or contact with the conveyance guide member or the conveyance roller during conveyance. A large potential difference may occur between the charged sheet and the conveyance guide member, particularly on the downstream side of the transfer unit in the sheet conveyance direction. When this sheet comes into contact with a conveyance guide member or the like, a sudden electric potential change may cause a discharge, and unfixed toner on the sheet may be scattered. Even when the discharge is not performed, the unfixed toner on the paper may move unintentionally due to excessive charging of the paper. Due to such phenomena, the toner image is disturbed and an abnormal image is generated.

Therefore, as a method for removing the charged charge on the paper that causes the abnormal image as described above, there has been proposed an image forming apparatus in which a static eliminating member that contacts the paper is arranged on the paper transport path, and an example thereof is patented. Reference 1 can be seen.
JP 2000-255812 A (page 4, FIG. 1-2)

  In the image forming apparatus described in Patent Document 1, a neutralizing brush that is a neutralizing member is disposed upstream of the image forming unit in the sheet conveying direction, and the sheet is neutralized by the neutralizing brush. However, in this configuration, there is no mention of the length or arrangement location of the static elimination brush in the paper width direction perpendicular to the paper conveyance direction. As described above, a roller such as a conveyance roller that contacts a sheet is easily charged by the roller itself. Therefore, special consideration must be given to the movement of charges from the roller to the sheet. If the neutralizing brush is not disposed at a position corresponding to the path of the roller extending in the paper conveyance direction, there is a possibility that effective neutralization cannot be realized. On the other hand, if the neutralizing brush is disposed over the entire width of the sheet, the neutralizing brush may be disposed at a portion where neutralization is unnecessary, and the cost of parts increases.

  It has been found that the charging of the paper tends to be severe during double-sided printing. This is because in double-sided printing, after printing the first side, it is necessary to feed the paper again to the image forming unit through a paper conveyance path in which a plurality of rollers are arranged in order to print the second side. The paper comes into contact with many rollers during this period, and becomes more easily charged, unlike the case where only one side is printed.

  The present invention has been made in view of the above points, and in an image forming apparatus having a double-sided printing function, it is possible to effectively remove the charged charge on a sheet received from a roller that rotates in contact with the sheet. An object of the present invention is to provide an image forming apparatus capable of realizing high-quality image formation.

  In order to solve the above problems, the present invention provides an image forming apparatus having a double-sided printing function that enables printing on the second side after printing the first side of the paper. A neutralizing member having a length substantially the same as the width of the roller in the paper width direction perpendicular to the paper conveyance direction is provided in the vicinity of the roller to perform, and this neutralization member corresponds to the locus of the roller extending in the paper conveyance direction. It was decided to place it in contact with the paper.

  In the image forming apparatus having the above-described configuration, the charge removal member is disposed at a position facing the roller with a sheet interposed therebetween.

  Further, in the image forming apparatus having the above-described configuration, the charge eliminating member is disposed at a location where the sheet conveyance path extending from the sheet feeding cassette and the sheet conveyance path on which the sheet is conveyed for printing the second surface merge. It was.

  The present invention also provides an image forming apparatus having a double-sided printing function that enables printing on the second side after printing the first side of the paper, and contacts the peripheral surface of the roller that rotates in contact with the paper. The static elimination member having a length substantially the same as the width of the roller in the paper width direction perpendicular to the paper conveyance direction is provided.

  According to the configuration of the present invention, in an image forming apparatus having a double-sided printing function, in the vicinity of a roller that rotates in contact with a sheet, the length is approximately the same as the width of the roller in a sheet width direction perpendicular to the sheet conveyance direction. The neutralization member is provided, and the neutralization member is located at a location corresponding to the locus of the roller extending in the paper conveyance direction and in contact with the paper. The charge removing member can effectively remove the charge received from the roller by the charge eliminating member. In particular, when performing double-sided printing, which is more likely to be charged, unlike when printing on only one side, it is possible to perform more effective sheet neutralization. Accordingly, it is possible to prevent scattering and movement of unfixed toner on the sheet due to charging due to contact with the roller at a position between the image forming unit and the fixing unit. Therefore, it is possible to obtain an image forming apparatus that can prevent the occurrence of abnormal images and can realize high-quality image formation.

  In addition, since the charge eliminating member is disposed at a position facing the roller with the sheet interposed therebetween, it is possible to remove the charged charges from the sheet simultaneously with the contact with the sheet roller. Thereby, the sheet can be quickly discharged, and the charge can be prevented from moving to a position away from the locus of the roller on the sheet. Therefore, it is possible to further improve the static elimination effect of the paper.

  In addition, since the static elimination member is disposed at a location where the paper conveyance path extending from the paper feed cassette and the paper conveyance path on which the paper is conveyed to print the second surface are joined, The member can neutralize both the sheet conveyed from the paper feed cassette and the sheet that has finished printing on the first side and is going to print on the second side. Thereby, it is possible to efficiently perform the charge removal of the sheet with a single charge removal member, and it is possible to reduce the component cost of the charge removal member. Therefore, the charge eliminating effect of the paper can be further enhanced.

  Further, in an image forming apparatus having a double-sided printing function, the static elimination having a length substantially the same as the width of the roller in the paper width direction perpendicular to the paper transport direction, which contacts the circumferential surface of the roller rotating in contact with the paper. Since the member is provided, it is possible to directly remove the electric charge charged on the peripheral surface of the roller by the charge eliminating member. As a result, the charging of the roller itself due to contact with the paper can be prevented. Accordingly, since the charge does not move from the roller to another sheet again, it is possible to prevent the sheet from being charged by the roller that is in contact with the sheet while being conveyed on the sheet conveyance path.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  First, the image output operation of the image forming apparatus according to the first embodiment of the present invention will be described while explaining the outline of the structure with reference to FIG. FIG. 1 is a left side view of a schematic vertical section showing a schematic structure of an image forming apparatus. In FIG. 1, the right side is the front side of the image forming apparatus, and the left side is the back side.

  As shown in FIG. 1, a paper feed cassette 3 is disposed below the main body 2 of the image forming apparatus 1. Inside the paper feed cassette 3, paper such as cut paper before printing is stacked and accommodated. Then, the sheets are separated and sent one by one toward the upper right of the sheet feeding cassette 3 in FIG. The paper feed cassette 3 can be pulled out horizontally from the front side of the main body 2, that is, from the right side in FIG.

  A paper feed path 4, a paper feed transport roller 5, a registration roller 6, an image forming unit 20, and a transfer unit 30 are disposed downstream of the paper feed cassette 3 in the paper transport direction. The sheet fed from the sheet feeding cassette 3 enters the sheet feeding sheet conveyance path 4, is conveyed by the sheet feeding conveyance roller 5, and reaches the registration roller 6. The registration roller 6 feeds the paper to the transfer unit 30 by correcting the oblique feeding of the paper and timing the toner image formed by the image forming unit 20.

  The image forming unit 20 includes a photosensitive drum 21 which is a rotating image carrier at the center thereof. The photosensitive drum 21 rotates clockwise in FIG. Around the photosensitive drum 21, a charging device 22, a developing device 23, and a drum cleaning device 24 are sequentially arranged along the rotation direction.

  On the other hand, image data signals such as characters, graphics, and patterns from an external computer (not shown) are transmitted to the image forming apparatus 1, and based on this image data, the optical unit 7 provided above the image forming unit 20. Laser light L to be controlled (two-dot chain line in the figure) is irradiated toward the photosensitive drum 21. Thereby, in the image forming unit 20, an electrostatic latent image of the original image is formed on the surface of the photosensitive drum 21. From this electrostatic latent image, a toner image is developed by a developing device 23 arranged to face the photosensitive drum 21. The toner image is transferred to a sheet fed synchronously by the registration roller 6 at a transfer nip portion formed by press contact between the photosensitive drum 21 and the transfer roller 31 of the transfer portion 30.

  A fixing unit 8, a discharge paper transport path 9, and a paper discharge unit 10 are disposed downstream of the image forming unit 20 and the transfer unit 30 in the paper transport direction. The sheet carrying the unfixed toner image in the transfer unit 30 is sent to the fixing unit 8 and heated and pressed by the heat roller and the pressure roller to fix the toner image. The sheet discharged from the fixing unit 8 is sent upward through a discharge sheet conveyance path 9 and is discharged by a discharge roller 11 to a sheet discharge unit 10 provided on the upper surface of the main body 2. The paper discharge unit 10 is provided on the upper surface of the main body 2 at a position where a printed paper can be taken out from the outside.

  A double-sided printing paper conveyance path 12 is disposed below the fixing unit 8 and the transfer unit 30 and between the paper feeding cassette 3. The double-sided printing paper conveyance path 12 branches from the middle of the discharge paper conveyance path 9, passes under the fixing unit 8 and under the transfer unit 30, and immediately upstream of the paper supply conveyance roller 5. It merges with the conveyance path 4.

  When performing double-sided printing, the sheet discharged from the fixing unit 8 is switched to the reverse direction and switched back immediately before being discharged to the sheet discharge unit 10 through the discharge sheet transfer path 9. . Then, the paper is sent to the double-sided printing paper transport path 12, merged with the paper feed paper transport path 4 immediately upstream of the paper feed transport roller 5, and sent again to the transfer unit 30.

  In the image forming apparatus 1 having the above-described configuration, the upstream side and the downstream side of the paper feed conveyance roller 5 on the paper feed path 4 and the vicinity of the discharge roller 11 of the discharge paper feed path 9. The neutralization brushes 13 to 15 that are neutralization members are provided at a total of three locations. The neutralizing brushes 13 to 15 are in contact with the paper passing through the conveyance path and remove the electric charge accumulated on the paper.

  Subsequently, regarding such a static elimination brush, the static elimination brushes 13 and 14 disposed on the upstream side and the downstream side of the sheet feeding conveyance roller 5 are taken as an example, and the detailed configuration thereof will be described with reference to FIGS. explain. 2 is a partially enlarged vertical cross-sectional left side view showing the periphery of the paper feed transport roller, FIG. 3 is a perspective view of the paper feed transport roller from the front, and FIG. 4 is the paper feed transport roller from the rear. FIG.

  Here, as shown in FIGS. 3 and 4, the paper feed transport roller 5 includes two common feed shafts 5 a extending in the paper width direction perpendicular to the paper transport direction, and having two relatively narrow paper feeds. It is comprised in the form which penetrates the conveyance roller 5 for use.

  As shown in FIGS. 3 and 4, the neutralizing brushes 13 and 14 are configured to have substantially the same length as the width of the paper feeding transport roller 5 in the paper width direction. The neutralizing brushes 13 and 14 are provided so that the brush portions 13b and 14b protrude from the base portions 13a and 14a. And the static elimination brushes 13 and 14 are being fixed to the flame | frame of the main body 2 with the base parts 13a and 14a so that the brush parts 13b and 14b may be located in paper conveyance space.

  As shown in FIGS. 2 and 3, the neutralizing brush 13 disposed on the upstream side of the paper feed transport roller 5 prints the paper feed path 4 extending from the paper feed cassette 3 and the second surface. Is provided at a location where the double-sided printing paper conveyance path 12 is conveyed. The neutralizing brush 13 is transported to a location corresponding to the locus of the paper feed transport roller 5 extending upstream in the paper transport direction with respect to the paper feed paper transport path 4, that is, immediately upstream of the paper feed transport roller 5. It arrange | positions so that the paper which passes a path | route may be contacted. Further, the neutralizing brush 13 is disposed on the double-sided printing paper conveyance path 12 so as to be in contact with the paper at a position facing the paper feeding conveyance roller 5 across the paper passing through the conveyance path.

  As shown in FIGS. 2 and 4, the neutralizing brush 14 disposed on the downstream side of the paper feed transport roller 5 is a portion corresponding to the locus of the paper feed transport roller 5 extending downstream in the paper transport direction, i.e., the feed brush. It is arranged immediately downstream of the paper transport roller 5 so as to contact the paper passing through the transport path.

  In this manner, in the image forming apparatus 1 having the double-sided printing function, in the vicinity of the paper feed transport roller 5 that rotates in contact with the paper, the length substantially equal to the width of the paper feed transport roller 5 in the paper width direction. The neutralizing brushes 13 and 14 as the neutralizing members are provided, and the neutralizing brushes 13 and 14 are locations corresponding to the trajectory of the sheet feeding conveyance roller 5 extending in the sheet conveying direction so as to come into contact with the sheet. Therefore, the charge received by the sheet from the roller can be effectively removed by the neutralizing brushes 13 and 14 disposed at appropriate positions. In particular, when performing double-sided printing, which is more likely to be charged, unlike when printing on only one side, it is possible to perform more effective sheet neutralization. As a result, it is possible to prevent scattering and movement of unfixed toner on the sheet due to charging due to contact with the sheet feeding conveyance roller 5 at a location between the image forming unit 20 and the fixing unit 8. Therefore, it is possible to obtain the image forming apparatus 1 that can prevent the occurrence of abnormal images and can realize high-quality image formation.

  Further, with respect to the double-sided printing paper conveyance path 12, the neutralizing brush 13 is disposed at a position facing the paper feeding conveyance roller 5 with the paper sandwiched therebetween, so that the paper is simultaneously brought into contact with the paper feeding conveyance roller 5. It becomes possible to remove the charged charge from. Accordingly, the sheet can be quickly discharged, and the charge can be prevented from moving to a position away from the locus of the sheet feeding conveyance roller 5 on the sheet. Therefore, it is possible to further improve the static elimination effect of the paper.

  Further, the neutralizing brush 13 is disposed at a location where the paper feeding paper conveyance path 4 extending from the paper feeding cassette 3 and the double-sided printing paper conveyance path 12 through which the paper is conveyed for printing the second surface merge. Therefore, the single static elimination brush 13 can neutralize both the paper conveyed from the paper feed cassette 3 and the paper which has finished printing on the first side and is going to print on the second side. Accordingly, it is possible to efficiently perform the charge removal of the sheet with the single charge eliminating brush 13, and it is possible to reduce the component cost of the charge eliminating brush. Therefore, the charge eliminating effect of the paper can be further enhanced.

  It should be noted that the neutralizing brush 15 disposed in the vicinity of the discharge roller 11 in the discharge sheet conveyance path 9 and immediately downstream thereof is also the above-described neutralization brush disposed on the upstream side and the downstream side of the sheet feeding conveyance roller 5. 13 and 14 is provided, and the discharge roller 11 is provided at an arrangement location based on the same conditions.

  Next, the detailed configuration of the image forming apparatus according to the second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a partially enlarged vertical cross-sectional left side view showing the periphery of the sheet feeding conveyance roller of the image forming apparatus. Since the basic configuration of this embodiment is the same as that of the first embodiment described with reference to FIGS. 1 to 4, the configuration common to the first embodiment is described in the drawings, and The description will be omitted.

  In the image forming apparatus 1 according to the second embodiment, the neutralizing brush 16 that is a neutralizing member is a portion corresponding to the back side of the sheet feeding conveyance roller 5 with respect to the sheet feeding sheet conveyance path 4, It is provided in contact with the peripheral surface of the paper transport roller 5. The configuration of the static elimination brush 16 has substantially the same length as the width of the paper feed conveyance roller 5 in the paper width direction, similarly to the static elimination brushes 13 to 15 described in the first embodiment.

  As a result, it is possible to directly remove the electric charges charged on the roller peripheral surface of the paper feed conveying roller 5 by the charge eliminating brush 16. As a result, it is possible to prevent the feeding roller 5 itself from being charged due to contact with the paper. Therefore, since the charge does not move again from the paper feed transport roller 5 to another paper, the paper is charged by the paper feed transport roller 5 that is in contact with the paper while being transported on the paper transport path. It is possible to prevent.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  For example, in the above-described embodiment, the neutralization brushes 13, 14, and 16 are provided for the paper feeding conveyance roller 5, and the neutralization brush 15 is provided for the discharge roller 11, so that the charge that the sheet receives from each roller is effectively removed. However, the location of the static elimination brush is not limited to these, and it may be provided for other rollers on the paper conveyance path.

  The present invention can be used in all image forming apparatuses having a duplex printing function.

1 is a left side view of a schematic vertical section of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a partial enlarged vertical cross-sectional left side view showing the periphery of a paper feed conveyance roller in FIG. 1. It is the perspective view which looked at the location of the conveyance roller for paper feeding of FIG. 1 from the front. It is the perspective view which looked at the location of the conveyance roller for paper feeding of FIG. 1 from back. FIG. 6 is a partially enlarged vertical cross-sectional left side view showing the periphery of a paper feed conveyance roller of an image forming apparatus according to a second embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Paper feed cassette 4 Paper feed paper conveyance path (paper conveyance path)
5 Feed roller (roller)
8 Fixing section 9 Paper transport path for discharge (paper transport path)
11 Paper transport path for duplex printing (paper transport path)
13-16 Static elimination brush (static elimination member)
20 Image forming section 30 Transfer section

Claims (4)

In an image forming apparatus having a double-sided printing function that enables printing on the second side after printing the first side of the paper,
In the vicinity of the roller rotating in contact with the paper, a static elimination member having a length substantially equal to the width of the roller in the paper width direction perpendicular to the paper conveyance direction is provided, and the static elimination member is extended in the paper conveyance direction. An image forming apparatus, wherein the image forming apparatus is disposed so as to be in contact with a sheet at a position corresponding to a locus of the roller.   The image forming apparatus according to claim 1, wherein the charge eliminating member is disposed at a position facing the roller with a sheet interposed therebetween.   2. The neutralizing member is disposed at a location where a sheet conveyance path extending from a sheet feeding cassette and a sheet conveyance path on which a sheet is conveyed for printing the second surface are merged. The image forming apparatus according to 2. In an image forming apparatus having a double-sided printing function that enables printing on the second side after printing the first side of the paper,
An image forming apparatus comprising: a neutralizing member that is in contact with a circumferential surface of a roller that rotates in contact with a sheet, and has a length substantially equal to the width of the roller in a sheet width direction perpendicular to the sheet conveyance direction.