JP2009122448A - Paper discharging device and image forming apparatus provided with same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper discharging device which discharges static electricity charged to recording paper after transferring by using conductive non-woven fabric and to provide an image forming apparatus using the same, in a simple constitution and at a low cost. <P>SOLUTION: The paper discharging device 120 is installed on a downstream side of a transfer part 12 for transferring a toner image to the recording paper 18 and discharges the static electricity which is charged to the recording paper 18. The paper discharging device 120 is provided with a plate like supporting member 120B which is extended in a direction nearly orthogonal to the transporting direction of the recording paper 18 on a back surface side of the recording paper 18 and a frame-like cover member 120C which is attached to a surface of the supporting member 120B for maintaining the surface of the supporting member 120B and the recording paper 18 in a state of non-contact without any electrostatic blocking between the two. In addition, the conductive unwoven cloth 125 extending along a longer direction of the supporting member 120B is interposed between the surface of the supporting member 120B and the cover member 120C. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an improvement in a sheet static eliminator that removes static electricity from a recording sheet charged by a transfer voltage, and an image forming apparatus using the same.

Japanese Patent No. 2595857

  Conventionally, it is known that when the recording paper after transfer is charged with static electricity, the running of the recording paper becomes unstable and problems such as paper wrinkles and image defects occur at the fixing unit. Therefore, in order to solve such a problem, a paper static eliminator that removes static electricity charged on the recording paper has been proposed. (For example, refer to Patent Document 1).

  Here, Patent Document 1 discloses a sheet static eliminator in which a sheet-like electrode made of a conductive nonwoven fabric is fixedly installed by a sticking means so as to be in non-contact with a recording sheet.

  An object of the present invention is to provide a sheet neutralizing device that neutralizes static electricity charged on a recording sheet after transfer with a conductive nonwoven fabric and an image forming apparatus using the same, with a simple configuration at low cost.

  In order to achieve the above object, a paper static eliminator according to claim 1 is a paper static eliminator provided on the downstream side of a transfer portion for transferring a toner image onto a recording paper and neutralizing static electricity charged on the recording paper. And electrostatically shielding the plate-like support member extending in the direction substantially orthogonal to the recording paper conveyance direction on the back side of the recording paper, and the surface of the supporting member and the recording paper. And a frame-shaped cover member that is attached to the surface of the support member, and is provided between the surface of the support member and the cover member along the longitudinal direction of the support member. It is characterized by interposing a conductive non-woven fabric extending.

  Here, the back side of the recording paper means the back side of the toner forming surface of the recording paper on which the toner image is formed. When the toner images are formed on both sides of the recording paper, The back side of the transfer surface of the recording paper onto which the toner image is transferred is assumed. Further, the surface of the support member refers to the surface on the side facing the recording paper.

  According to a second aspect of the present invention, in the configuration of the first aspect, the frame-shaped cover member includes a plurality of ribs extending along a conveyance direction of the recording paper, and the recording paper This also serves as a conveyance guide member that guides conveyance in a predetermined direction.

  The sheet static eliminator according to claim 3 is the configuration according to claim 1 or 2, wherein the conductive nonwoven fabric is adhered to a thin plate-like resin member, and the longitudinal direction of the thin plate-like resin member. It is fixed to the support member at both ends.

  According to a fourth aspect of the present invention, there is provided the sheet static eliminator according to any one of the first to third aspects, wherein the recording sheet is conveyed substantially vertically upward from the transfer portion, and the transferred toner image is displayed. The distance between the fixing unit fixed on the recording sheet and the transfer unit is shorter than the maximum sheet passing size.

  An image forming apparatus according to a fifth aspect includes the sheet static eliminator according to any one of the first to fourth aspects and a color image forming unit that forms a color image on a recording sheet. .

  According to the first aspect of the present invention, a sheet static eliminator that can easily replace and recycle the static electricity charged on the recording sheet at the transfer section while maintaining a non-contact state with the recording sheet is inexpensive with a simple configuration. Can be realized.

  According to the second aspect of the present invention, it is possible to contribute to downsizing and cost reduction of the apparatus by combining the cover member of the sheet static eliminator and the conveyance guide member for guiding the conveyance of the recording sheet.

  According to the invention described in claim 3, a sheet static eliminator that prevents the floating and peeling of the conductive nonwoven fabric in advance and maintains good running performance of the recording paper, and is easy to attach and recycle the conductive nonwoven fabric. Can be realized easily.

  According to the invention described in claim 4, charging of the recording paper after transfer is particularly problematic, and the image formation is configured such that the distance between the transfer portion and the fixing portion is short and the recording paper is conveyed in the direction against gravity. The sheet neutralizing apparatus according to the present invention can be suitably applied to the apparatus.

  According to the fifth aspect of the present invention, since the transfer voltage is higher than that of the monochrome image forming apparatus, the sheet neutralizing apparatus according to the present invention is suitable for a color image forming apparatus in which charging of the recording sheet after transfer is particularly problematic. Can be applied to.

  Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.

  First, a schematic configuration of an embodiment of an image forming apparatus to which the present invention can be applied will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of a tandem color image forming apparatus 100 to which the present invention is applicable.

  In this image forming apparatus 100, color image information of a color original read by the image reading apparatus 102, color image information sent from a personal computer or an image data input device (not shown), and the like are input, and the input image Image processing is performed on the information.

  In FIG. 1, 1Y, 1M, 1C, and 1K are image forming units that form toner images of yellow (Y), magenta (M), cyan (C), and black (K), respectively. The endless intermediate transfer belt 9 stretched by a roll is arranged in series in the order of 1Y, 1M, 1C, and 1K along the traveling direction. The intermediate transfer belt 9 is an intermediate transfer body to which toner images of respective colors sequentially formed by these image forming units 1Y, 1M, 1C, and 1K are transferred in a state of being superimposed on each other. Between the primary transfer rolls 6Y, 6M, 6C, and 6K disposed to face the photosensitive drums 2Y, 2M, 2C, and 2K, which are electrostatic latent image holders corresponding to 1Y, 1M, 1C, and 1K, respectively. And is configured to be able to circulate in the direction of the arrow. Then, the toner images of the respective colors transferred in multiple on the intermediate transfer belt 9 are collectively transferred onto a recording paper 18 as a recording medium fed from the paper feeding cassette 17 or the like. Thereafter, the recording sheet 18 on which the unfixed toner image is formed is discharged by a sheet discharging device 120 that also serves as a sheet traveling guide and guided to a fixing device (fixing unit) 15, and a color image is fixedly formed on the surface thereof. The recorded recording paper 18 is discharged to the outside.

  Here, the image reading apparatus 102 illuminates a document placed on the platen glass with a light source (not shown), and reflects a reflected light image from the document with an image reading element including a CCD sensor or the like via a scanning optical system. It is configured to read at a predetermined resolution.

  The image forming units 1Y, 1M, 1C, and 1K are configured in the same manner. Broadly speaking, the photosensitive drums 2Y, 2M, 2C, and 2K that rotate at a predetermined rotational speed in the direction of the arrow, and the photosensitive drums. Charging rolls 3Y, 3M, 3C, 3K as charging means for uniformly charging the surfaces of the drums 2Y, 2M, 2C, 2K, and images corresponding to the respective colors on the surfaces of the photosensitive drums 2Y, 2M, 2C, 2K Exposure devices 4Y, 4M, 4C, and 4K that form an electrostatic latent image by exposure, and developing devices 5Y, 5M, and 5C that develop the electrostatic latent images formed on the photosensitive drums 2Y, 2M, 2C, and 2K, 5K, toner cartridges 10Y, 10M, 10C, and 10K that are detachably arranged and supply toner of a predetermined color to the developing devices 5Y, 5M, 5C, and 5K, drum cleaning devices 7Y, 7M, 7C, and 7K, and the like It is al configuration.

  Further, in the present embodiment, the photosensitive drums 2Y, 2M, 2C, and 2K are photosensitive materials made of an organic photosensitive material, an amorphous selenium photosensitive material, an amorphous silicon photosensitive material, or the like on the surface of a metal drum that rotates in the direction of the arrow. A body layer is formed, and the charging rolls 3Y, 3M, 3C, and 3K are configured to come into contact with the surfaces of the photosensitive drums 2Y, 2M, 2C, and 2K and to charge the photoreceptor layers to a predetermined potential. ing.

  The image forming process in the image forming apparatus configured as described above will be described using the image forming unit 1Y that forms a yellow toner image as a representative example.

  First, the surface of the photosensitive drum 2Y is uniformly charged by the charging roll 3Y. Next, for example, based on the image information read by the image reading device 102, scanning exposure corresponding to the yellow image is performed by the laser beam output from the exposure device 4Y, and the surface of the photosensitive drum 2Y corresponds to the yellow image. An electrostatic latent image is formed.

  The electrostatic latent image corresponding to the yellow image is converted into a yellow toner image by the developing device 5Y, and is primarily transferred onto the intermediate transfer belt 9 by the pressing force and electrostatic attraction force of the primary transfer roll 6Y constituting a part of the primary transfer unit. Is done. The yellow toner remaining on the photosensitive drum 2Y after the primary transfer is scraped off by the drum cleaning device 7Y. Thereafter, the surface of the photosensitive drum 2Y is neutralized by the drum neutralizing device 8Y and then charged again by the charging roll 3Y for the next image forming cycle.

  In the present image forming apparatus 100 that performs multicolor image formation, an image forming process similar to the above is performed at the timing in consideration of the relative position difference between the image forming units 1Y, 1M, 1C, and 1K. This is also performed in 1M, 1C, and 1K, and a full color toner image is formed on the intermediate transfer belt 9 in a superimposed state. As the intermediate transfer belt 9, for example, a flexible synthetic resin film such as polyimide is formed in a strip shape, and both ends of the synthetic resin film formed in the strip shape are connected by means such as welding, thereby being endless. What was formed in the shape of a belt can be used.

  The full-color toner image primarily transferred onto the intermediate transfer belt 9 is secondarily transferred onto the recording paper 18 conveyed to the secondary transfer position at a predetermined timing. Specifically, a predetermined transfer voltage is applied between the backup roll 13 that supports the intermediate transfer belt 9 and the secondary transfer roll 12 that is in pressure contact with the backup roll 13 at a predetermined timing. Secondary transfer is performed by suction force. The residual toner on the intermediate transfer belt 9 that could not be secondarily transferred onto the recording paper 18 is transported to the belt cleaning device 14 as it is adhered on the intermediate transfer belt 9, and is transferred by the belt cleaning device 14. It is removed from the belt 9 to prepare for the next image formation.

  On the other hand, recording paper 18 having a predetermined size is fed from a paper feed cassette 17 serving as a recording paper storage unit disposed in the lower part of the image forming apparatus 100 by a paper feed roll 17a. The fed recording paper 18 is conveyed to a secondary transfer position of the intermediate transfer belt 9 by a plurality of conveying rolls 19 and registration rolls 20 at a predetermined timing. Then, as described above, the full color toner image is transferred onto the recording paper 18 from the intermediate transfer belt 9 by the secondary transfer roll 12 and the backup roll 13 constituting the secondary transfer means (transfer section). Is done.

  The recording paper 18 on which the full-color toner image is secondarily transferred from the intermediate transfer belt 9 is separated from the intermediate transfer belt 9, and then the paper discharger that also serves as a travel guide member disposed on the downstream side of the secondary transfer means. The apparatus 120 removes static electricity charged on the surface by the transfer voltage and conveys it to the fixing device 15 so that the toner image is fixed on the recording paper 18 by heat and pressure. It has become. The recording sheet 18 after fixing is discharged onto a discharge tray 24 through a discharge roll 23. In the image forming apparatus 100 according to the present embodiment, in order to reduce the size of the apparatus, a fixing device 15 is disposed in the vicinity of the secondary transfer roll 12 so as to be close to the secondary transfer transfer roll 12. The transport path between the secondary transfer unit composed of the backup roll 13 and the fixing device 15 is shortened. Specifically, in the present embodiment, the recording paper 18 that has passed through the secondary transfer unit is conveyed substantially vertically upward, and the disposition distance between the secondary transfer unit and the fixing device 15 is the maximum sheet passing size. It is set to be shorter than (A3 size in this example).

  Next, the configuration of the sheet neutralizing apparatus according to the present invention will be described with reference to FIG. Here, FIG. 2 is a schematic perspective view showing the configuration of the sheet static eliminator according to the present invention.

  As shown in FIG. 2, the sheet neutralizing device 120 according to the present embodiment is disposed on the downstream side of the secondary transfer roll 12 (between the secondary transfer roll 12 and the fixing device 15). It also serves as a travel guide member that guides the recording paper 18 that has passed through the secondary transfer portion constituted by the transfer roll 12 and the backup roll 13 to the fixing device 15.

  The sheet neutralizing device 120 extends in the axial direction of the secondary transfer roll 12 and has a substantially L-shaped support member 120B disposed opposite to the back surface of the recording sheet 18, and a conductive member attached to the surface of the support member. The non-woven fabric 125 and a frame-shaped cover member 120C attached to the support member 120B with the conductive non-woven fabric 125 interposed therebetween.

  Here, the support member 120B is a substantially L-shaped member that has a facing surface 121 that faces the back surface of the recording paper 18 and a plane 123 that is substantially orthogonal to the facing surface 121, and is formed of stainless steel or the like. In order to prevent the charging, high resistance grounding of about 200 MΩ is used. The support member 120B according to the present embodiment is configured as a member having a substantially L-shaped cross section, but may be formed as a flat plate member having only the facing surface 121 to which the conductive nonwoven fabric 125 is fixed. Good.

  Further, the conductive nonwoven fabric 125 is formed on a thin plate-like resin member (in this embodiment, for example, a PET sheet) 127 having substantially the same shape as the facing surface 121 of the support member 120B, except for both longitudinal ends 127e thereof. The both ends 127e of the PET sheet 127 are fixed to each other by attaching them to both ends in the longitudinal direction of the opposing surface 121 of the support member 120B. In the present embodiment, as the conductive nonwoven fabric 125, DENKITOL (registered trademark) manufactured by Japan Vilene Co., Ltd. is used, and this conductive nonwoven fabric 125 is attached to a PET sheet having a thickness of 125 μm.

  The cover member 120C is a substantially L-shaped resin frame that follows the surface shape of the support member 120B, and a portion corresponding to the facing surface 121 of the support member 120B is opened. Are provided with a plurality of rib members 129, 129... Arranged in parallel in the axial direction (longitudinal direction) at a predetermined interval along the conveyance direction of the recording paper 18 (arrow direction in the figure). .

  In the sheet neutralizing device 120 configured as described above, the conductive nonwoven fabric 125 having a neutralizing function is applied to the recording sheet 18 by the plurality of rib members 129, 129... Provided in the opening of the cover member 120C. Since it can be maintained in a non-contact state without being electrostatically shielded and interposed between the support member 125B and the conveyance direction of the recording sheet 18 can be guided, the conveyance guide member and the sheet neutralizing device can be guided. It can be used in combination, contributing to downsizing and cost reduction of the device.

  Further, the conductive nonwoven fabric 125 is affixed to the PET sheet 127 and both ends 127e of the PET sheet 127 are attached to the support member 120B, so that the conductive nonwoven fabric 125 is directly adhered to the support member 125B. This makes it possible to simplify the attachment work and replacement work of the conductive nonwoven fabric 125 and facilitate the recycling of the expensive conductive nonwoven fabric 125.

  Furthermore, the rib member 129 of the cover member 120C can guide the conveyance direction of the recording paper 18 and can maintain a non-contact state in which an appropriate separation distance between the conductive nonwoven fabric 125 and the recording paper 18 is maintained. It is possible to realize a static elimination performance that is stable over time for the paper 18. In addition, the conductive nonwoven fabric 125 can be easily attached by sandwiching the conductive nonwoven fabric 125 with the support member 120B by a plurality of ribs 129, 129... Provided on the cover member 120C. The conductive nonwoven fabric 125 can be prevented from being deformed due to the generation of undulations and wrinkles over time, and can contribute to the stable conveyance of the recording paper 18 over time.

  The image forming apparatus to which the sheet neutralizing apparatus according to the present invention can be applied is not limited to the image forming apparatus having the above-described configuration, but the occurrence of paper wrinkles and image defects due to charging of the recording sheet after transfer is caused. This is particularly suitable for an image forming apparatus having a configuration in which the distance between the transfer device and the fixing device, which is a problem, is short, and the sheet is conveyed substantially vertically upward against the direction of gravity. Furthermore, the present invention can be suitably applied to a color image forming apparatus in which a transfer voltage is higher than that of a monochrome image forming apparatus.

1 is a schematic configuration diagram showing an embodiment of an image forming apparatus according to the present invention. 1 is a schematic perspective view illustrating a configuration of an embodiment of a sheet static eliminator according to the present invention.

Explanation of symbols

  1Y, 1M, 1C, 1K: image forming unit, 2Y, 2M, 2C, 2K: photosensitive drum, 3Y, 3M, 3C, 3K: charging roll, 4Y, 4M, 4C, 4K: exposure device, 5Y, 5M, 5C , 5K: Developing device, 6Y, 6M, 6C, 6K: Primary transfer roll, 7Y, 7M, 7C, 7K: Drum cleaning device, 9: Intermediate transfer belt, 10Y, 10M, 10C, 10K: Toner cartridge, 12: Two Next transfer roll, 13: Backup roll, 14: Belt cleaning device, 15: Fixing device, 17: Paper feed cassette, 18: Recording paper, 100: Tandem color image forming device, 102: Image reading device, 120: Paper neutralization Device, 120B: Support member, 120C: Cover member, 121: Opposing surface, 125: Conductive nonwoven fabric, 127: PET sheet, 129: Re Member

Claims (5)

A sheet neutralizing device provided on the downstream side of a transfer unit for transferring a toner image to a recording sheet and neutralizing static electricity charged on the recording sheet,
A plate-like support member extending on the back side of the recording paper in a direction substantially orthogonal to the conveyance direction of the recording paper;
Maintaining the surface of the support member and the recording paper in a non-contact state without electrostatic shielding, and a frame-shaped cover member attached to the surface of the support member,
A sheet static eliminator characterized in that a conductive non-woven fabric extending along the longitudinal direction of the support member is interposed between the surface of the support member and the cover member.   The frame-shaped cover member has a plurality of ribs extending along the conveyance direction of the recording paper, and also serves as a conveyance guide member for guiding conveyance of the recording paper in a predetermined direction. The sheet static eliminator according to claim 1.   The conductive nonwoven fabric is bonded to a thin plate-like resin member and fixed to the support member at both longitudinal ends of the thin plate-like resin member. The sheet static eliminator described in 1.   The recording sheet is conveyed substantially vertically upward from the transfer unit, and the distance between the fixing unit that fixes the transferred toner image on the recording sheet and the transfer unit is shorter than the maximum sheet passing size. The sheet static eliminator according to any one of claims 1 to 3.   An image forming apparatus comprising: the sheet static eliminator according to claim 1; and a color image forming unit that forms a color image on a recording sheet.

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