JP2005338311A - Full color printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the quality of formed images by preventing contact between a conductive layer being in an end part of a belt photoreceptor and a contact electrifier in a full color printer. <P>SOLUTION: The full color printer is provided with developing units of four colors of black, yellow, magenta, and cyan, the photoreceptor belt, and the contact electrifier for electrifying the photoreceptor belt, and a bearing which receives a shaft of a charging brush of the contact electrifier is provided with a rib to prevent contact between the contact charging brush and the conductive layer formed on the photoreceptor belt. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a multicolor image forming apparatus, and more particularly to a full color printer that forms a multicolor image by superimposing a plurality of color toner images by electrophotography based on a print signal transmitted from a host apparatus.

  A multicolor image forming apparatus that can be applied to a color printer, a color copying machine, a color facsimile, and the like has a plurality of developing units each containing toner of different colors, and the plurality of developing units are configured such that the toner adheres to the surface of the photoreceptor. Are arranged in order. After the surface of the photosensitive member is uniformly charged by the contact charger, the photosensitive member is irradiated with laser light from the exposure device, and an electrostatic latent image corresponding to the image signal is formed. The electrostatic latent image formed on the surface of the photoreceptor is visualized as a toner image by the developing device and transferred to the intermediate transfer member. The toner image transferred to the intermediate transfer member is transferred to a sheet, and the toner image transferred to the sheet is fixed on the sheet by a fixing device, so that a multicolor image is printed. An example of such a multicolor image forming apparatus is disclosed in Patent Document 1.

  Here, the contact between the conductive layer on the photoreceptor and the contact charger to prevent a short circuit is an important technique for preventing image defects and abnormal operation of the printer and obtaining high print quality of multicolor images. .

JP 2000-338740 A (FIG. 1)

  In the prior art, there is a problem that the conductive layer at the end of the photoconductor is in contact with the contact charger, the charging voltage is lowered and image defects occur, or electrostatic noise is generated and the printer operates abnormally. .

  An object of the present invention is to provide a multicolor image forming apparatus that prevents contact between a conductive layer of a photosensitive member and a contact charger and does not cause image defects or malfunctions.

  Another object of the present invention is to provide a multicolor image forming apparatus that has a simple and compact structure for preventing contact between a conductive layer of a photoreceptor and a contact charger.

  In order to prevent contact between the contact charger and the conductive layer on the photoconductor, the full-color printer of the present invention charges a photoconductor unit having a conductive layer at the end of the photoconductor and the surface of the photoconductor belt. A contact charger, an exposure device for forming an electrostatic latent image based on image information on the surface of the photosensitive belt, and toners of different colors are accommodated to visualize the electrostatic latent image as a toner image. A plurality of developing units, an intermediate transfer member that forms a color image by sequentially superimposing toner images of each color formed on the photosensitive belt, and a transfer unit that transfers the color image of the intermediate transfer member to a sheet, The charger is installed inside the conductive layer, and a gap is provided between the charging brush and the conductive brush so that the charger does not contact and short-circuit the conductive layer.

  In the full color printer of the present invention, the end portion of the contact charger is disposed inside the end portion of the photoreceptor. In the full color printer of the present invention, a member that restricts the position of the contact charger is provided so that the contact charger does not contact the conductive layer or the conductor.

  Further, in the full-color printer of the present invention, in order to prevent contact between the contact charging brush and the conductive layer on the photoconductor, a photoconductor unit having a conductive layer at the end of the photoconductor and the surface of the photoconductor belt are provided. A charging contact charging brush, an exposure device that forms an electrostatic latent image based on image information on the surface of the photosensitive belt, and a toner image of each different color, and the electrostatic latent image is visualized as a toner image A plurality of developing units, an intermediate transfer member that forms a color image by sequentially superimposing toner images of respective colors formed on the photosensitive belt, and a transfer unit that transfers the color image of the intermediate transfer member to a sheet. In the full-color printer, a member for preventing the conductive layer of the photoconductor and the contact charging brush from coming into contact with each other and short-circuiting is provided.

  Further, in the full color printer of the present invention, the mechanism is simplified by integrating the bearing of the charging brush, the conductive layer of the photosensitive member, and the member that prevents the charging brush from contacting and short-circuiting.

  Further, in the full color printer of the present invention, the charging brush bearing, the cleaning shaft bearing for cleaning the charging brush, the conductive layer of the photosensitive member, and the member that prevents the charging brush from contacting and short-circuiting are integrated, The mechanism was simplified.

  In the multicolor image forming apparatus of the present invention, since the contact between the charging brush and the photosensitive belt conductive portion is prevented, charging of the photosensitive belt and the latent image are stabilized, and a highly accurate image can be obtained.

  Hereinafter, details of the present invention will be described with reference to the drawings.

  Hereinafter, this embodiment will be described with reference to FIG. The main body of the full color printer 25 is a developing device 1 to 4 having toners of four colors (black, yellow, cyan, magenta), an exposure device 5, a contact charging brush 8, a photosensitive belt 22, an intermediate transfer member 21, a registration roller 12, and a transfer. A roller 13, a static eliminator 15, a fixing device 19, a paper discharge roller 18, and a paper feed cassette 6 are provided as main components.

  Next, the operation of the full color printer 25 will be described. The contact charging brush 8 uniformly charges the surface of the photosensitive belt 22 by a print start signal from a host device (not shown). Subsequently, the exposure device 5 irradiates the surface of the photosensitive belt 22 with the laser beam 7 based on the print data sent from the host device, thereby forming an electrostatic latent image. The toner image is made visible by adhering the toner image to the photosensitive belt 22 by any one of 4. The photosensitive belt 22 is rotated in a direction indicated by an arrow P by a driving source (not shown), and the toner on the photosensitive belt 22 is transferred to the intermediate transfer body 21.

  In the case of full-color printing, the above steps are repeated 3 to 4 times while switching the developing devices 1 to 4. A visible image is formed on the intermediate transfer member 21 with toner of a single color or a plurality of colors, and when a desired transfer is completed or in advance, a stack of paper 27 such as cut paper is fed from the paper feed cassette 6. Each sheet is pulled out by the roller 10 and waits at the registration roller 12. At the timing when the position of the visible image formed on the intermediate transfer member 21 coincides with the transfer position on the sheet, the sheet waiting on the registration roller 12 starts to be transported again, and at the position of the transfer roller 13. Transfer the toner image onto the paper. The sheet is peeled off from the intermediate transfer member 21 by the static eliminator 15 and conveyed. At this time, an unfixed toner image is adhered on the sheet, and the unfixed toner image is fixed on the sheet by the fixing device 19 and then discharged to the sheet discharge tray 28 by the sheet discharge roller 18.

  On the surface of the intermediate transfer member 21, toner that has not been transferred to the paper during transfer remains. The toner remaining on the surface of the intermediate transfer member 21 is removed by the cleaner 20. In addition, toner may remain on the surface of the photosensitive belt 22 without being transferred to the intermediate transfer body 21. The toner remaining on the surface of the photoreceptor belt 22 is removed by another cleaner 23. Thereafter, the photosensitive belt 22 is charged again by the contact charging brush 8.

  Next, the photosensitive belt unit 101 of this embodiment will be described in detail with reference to FIG. The photosensitive belt 22 is suspended by three rollers, a driving roller 102, a driven roller 103, and a tension roller 104. The tension roller 104 applies tension by a tension spring 107 suspended on an arm 106 supported around an arm rotation point 105. The drive roller 102 rotates so as to move the photosensitive belt 22 in the direction of arrow P by power from a drive source (not shown). At that time, the driven roller 103 receives the conveying force of the photosensitive belt 22 and follows the direction of the arrow Q.

  The bias brush contacts the conductive layer at the end of the photoreceptor belt 22 to bias the photoreceptor. The conductive layer may have a gap from the end of the photoreceptor belt 22. The contact charging brush 8 is in contact with the photosensitive belt 22 to charge the surface of the photosensitive belt 22.

  The positional relationship between the contact charging brush 8 and the photosensitive belt 22 will be described with reference to FIG. The contact charging brush 8 is provided so that the end of the charging brush is located on the end of the photosensitive belt 22 and the inside of the conductive layer 22a. As a result, contact between the conductive layer of the photosensitive member and the contact charger is prevented, and image defects and malfunction of the printer are prevented.

  A means for preventing contact between the contact charging brush 8 and the conductive portion on the photosensitive belt 22 will be described with reference to FIG. By providing the insulating collars 108 on both sides of the contact charging brush 8, it is possible to prevent the end of the photoreceptor belt 22 or the conductive layer 22 a of the photoreceptor belt 22 from touching the end of the contact charging brush 8. Prevent defects and printer malfunctions.

  Further, as shown in FIG. 5, the bearings 109 a and 109 b that receive the shaft 8 a of the contact charging brush 8, the bearing of the cleaning shaft 111 that cleans the contact charging brush, and the rib 110 are integrally formed on the bearing 109 a, It is possible to prevent the end portion of the contact charging brush 8 from coming into contact with the conductive layer 22a of the photosensitive belt 22 and short-circuiting, and to simplify and compact the structure.

1 is a schematic diagram illustrating a configuration of a full-color printer according to an embodiment. FIG. FIG. 3 is a schematic diagram of a photoreceptor belt unit provided in the full color printer of the embodiment. Explanatory drawing of the contact prevention means of the charging brush of a full-color printer of an Example, and a photoreceptor belt electroconductive part. Explanatory drawing of the contact prevention means of the charging brush of a full-color printer of an Example, and a photoreceptor belt electroconductive part. Explanatory drawing of the contact prevention means of the charging brush of a full-color printer of an Example, and a photoreceptor belt electroconductive part.

Explanation of symbols

  1, 2, 3, 4 ... developer, 5 ... exposure device, 6 ... feed cassette, 7 ... laser beam, ... contact charger, 10 ... feed roller, 12 ... registration roller, 13 ... transfer roller, 15 ... Static eliminator, 18 ... discharge roller, 19 ... fixing device, 20, 23 ... cleaner, 21 ... intermediate transfer member, 22 ... photoconductor belt, 22a ... conductive layer, 25 ... full-color printer, 27 ... paper, 28 ... paper discharge Tray, 101 ... photosensitive belt unit, 102 ... driving roller, 103 ... driven roller, 104 ... tension roller, 105 ... arm rotation point, 106 ... arm, 107 ... tension spring, 108 ... collar, 109a, 109b ... bearing, 110: Rib, 111: Cleaning shaft.

Claims (5)

A photoconductor unit having a conductive layer at the end of the photoconductor, a contact charger for charging the surface of the photoconductor, an exposure device for forming an electrostatic latent image based on image information on the surface of the photoconductor, A plurality of developing units that store toners of different colors and visualize the electrostatic latent images as toner images, and a color image obtained by sequentially superimposing the toner images of the respective colors formed on the photoreceptor are transferred onto a sheet. In full-color printers equipped with transfer means,
A full-color printer characterized in that a member for restricting the position of the contact charger is disposed to isolate the contact charger from the conductive layer, and a gap is provided between the contact charger and the conductive layer.   2. The contact charger according to claim 1, wherein the contact charger is installed so that an end portion thereof is located inside an end portion of the photoconductor, and the contact charger is isolated from a conductive layer of the photoconductor end portion. Full color printer. A photosensitive unit having a conductive layer at the end of the photosensitive member, a contact charging brush for charging the surface of the photosensitive belt, and an exposure apparatus for forming an electrostatic latent image based on image information on the surface of the photosensitive belt A plurality of developing units that store toners of different colors and visualize the electrostatic latent images as toner images, and a color image obtained by sequentially superimposing the toner images of the respective colors formed on the photosensitive belt In a full-color printer with transfer means for transferring to
A full-color printer comprising a member that isolates the conductive layer of the photosensitive member from the contact charging brush and prevents a short circuit between the conductive layer and the contact charging brush.   4. The contact charging brush bearing and an isolation member for preventing a short circuit between the conductive layer of the photoconductor and the contact charging brush are formed integrally. Color printer. A bearing for the contact charging brush, a bearing for a cleaning shaft for cleaning the contact charging brush, and an isolation member for preventing the contact charging brush from being short-circuited to the conductive layer of the photoreceptor are integrally formed. The color printer according to claim 4, wherein:

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