JP2005227592A - Belt photoreceptor driving mechanism and printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent occurrence of image defects due to faulty transfer even when foreign substances such as toner, paper dust and carrier enter the gap between a belt photoreceptor and a roller which drives or supports the belt photoreceptor. <P>SOLUTION: In a belt photoreceptor driving mechanism comprising a driving roller disposed on the inner side of a belt photoreceptor to circularly drive the belt photoreceptor; a driven roller which rotates with circular movement of the belt photoreceptor in a following manner; and a tension roller which applies tension to the belt photoreceptor and rotates with circular movement of the belt photoreceptor in a following manner, a surface roughness Rmax of the driving or driven roller located in a transfer position is set to 50S-200S. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrophotographic apparatus that uses a laser or an LED to transfer an image formed on a photosensitive member by an electrophotographic process, such as a printer, a copying machine, and a facsimile, onto a transfer member represented by paper and record the image. More particularly, the present invention relates to a belt photoconductor driving device in such an electrophotographic apparatus in which a photoconductor is made of an endless belt, and the belt photoconductor is rotated around a plurality of rollers.

  Conventionally, in this type of belt photoreceptor driving device, as shown in FIG. 7, an endless belt photoreceptor 1 is stretched between a driving roller 2, a tension roller 3 and driven rollers 4, 5, and a roller shaft 6 of the driving roller 2. The rotation roller is transmitted to rotate the driving roller 2 to rotate the tension roller 3 and the driven rollers 4 and 5 respectively, and the belt photosensitive member 1 is conveyed in the direction indicated by the arrow in the figure.

Reference numeral 8 in the figure denotes a compression spring used to urge the roller shaft 7 to apply tension to the belt photoreceptor 1 and to control the meandering of the belt photoreceptor 1.
In addition to the rotational driving of the belt photoreceptor 1, an electrophotographic process such as charging, optical writing, development, transfer, and cleaning is repeated to repeatedly form an image on the belt photoreceptor 1, and the image is a transfer material. It was transferred onto paper.

  However, due to printing for a long time, foreign matter {toner, carrier and dust in the atmosphere (mainly paper dust)} enters inside the belt photoreceptor 1, and the inner surface of the belt photoreceptor 1 and the driving roller 2. In addition, it adheres to the surfaces of the tension roller 3 and the driven rollers 4 and 5 and the friction coefficient with the belt photoreceptor 1 decreases.

  Further, when a foreign material having a relatively large diameter such as a carrier is mixed between the belt photosensitive member 1 and each of the rollers, the mixed foreign material pushes the surface of the belt photosensitive member 1 into a convex shape and deforms it.

  The convex portions on the belt photoconductor 1 have a problem that the surface charge is concentrated and the image quality is deteriorated such as white spots in printing. In particular, when foreign matter is mixed between the roller 4 and the belt photoreceptor 1 paired with the transfer unit, a transfer omission defect is likely to occur with a high probability.

  As a method for dealing with this problem, the installation of a cleaning member inside the belt photoreceptor has been proposed (for example, see Patent Documents 1 and 2).

JP-A-5-257408 (page 1-3, FIG. 1)

JP-A-7-104611 (page 1-3, FIG. 1)

  However, such a method of installing the cleaning mechanism inside the belt photoconductor has complicated the apparatus and causes an increase in cost.

  SUMMARY OF THE INVENTION An object of the present invention is to prevent a reduction in image quality due to foreign matters (dust such as carrier, toner, and paper dust) entering the inside of a belt photoreceptor at low cost without complicating the apparatus. .

  The present invention is characterized in that the surface roughness Rmax of the driving or driven roller installed at the transfer position is 50S to 200S.

  The coefficient of static friction between the driving roller or driven roller and the belt photoreceptor may be 0.2 or more. In addition, a pressing member may be provided on the outer periphery of the driving or driven roller, and a foreign matter storage member for storing the carrier, toner, dust and the like scraped off by the pressing member may be provided. Furthermore, the pressing member may be a permanent magnet.

  According to the present invention, foreign matter that has entered the inside of the belt photoconductor can be captured in the concave portion of the surface of the belt conveyance roll, so that it is possible to prevent image quality deterioration due to convex deformation of the surface of the photoconductor belt or transfer failure due to foreign matter. can do.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 3 shows the overall schematic configuration of the internal mechanism of the image forming apparatus incorporating the photosensitive belt driving device 40 according to the present invention. The photoreceptor belt driving device 40 includes a belt photoreceptor 10 whose surface is made of an organic material, and rotationally drives the belt photoreceptor 10 in the direction of the arrow in the figure.

  Around the belt photoreceptor 10, process devices such as a charger 20, a latent image writing light source 21, a developing device 22, a transfer device 23, an erase light source 24, and a cleaning device 25 are installed.

  A sheet feeding roller 26 and a sheet feeding cassette 27 are provided below the transfer unit 23, and a sheet conveyance path 28, a fixing unit 29, and a sheet discharge roller 30 are installed above the transfer unit 23.

  Printing on a sheet by a printing apparatus including the belt photoreceptor driving device 40 according to the present invention is performed by first charging the belt photoreceptor 10 driven by the photoreceptor belt driving apparatus 40 at a rotational speed of 40 cm / s. The device 20 is used to charge about -600V.

  Next, the latent image writing light source 21 composed of an LED having a resolution of 1200 dpi performs light irradiation based on the image information to form an electrostatic latent image on the surface of the belt photoreceptor 10.

  Thereafter, the toner supplied by the developing device 22 is attached to the belt photoreceptor 10 to visualize the electrostatic latent image as a toner image.

  A two-component developer is used as the developer, a Mg-based ferrite carrier having an average particle diameter of 60 μm is used as the carrier, and a polyester-based toner having an average particle diameter of 8 μm is used as the toner.

  The toner image is transferred by using the transfer device 23 onto the paper 31 supplied from the paper supply cassette 27 to the transfer device 23 via the paper supply roller 26.

  Thereafter, the paper 31 holding the toner image is sent to the fixing device 29 through the paper conveyance path 28, fixed as a permanent image, and discharged to the outside by the paper discharge roller 30.

  Further, the belt photoreceptor 10 after the image transfer is subjected to charge removal by the erase light source 24 and removal of residual toner by the cleaner 25, and is prepared for the next image formation.

  Here, as shown in FIG. 1, the photosensitive belt driving device 40 according to the present invention spans the belt photosensitive member 10 over the driving roller 11, the driven rollers 13 and 14, and the tension roller 12, and the roller shaft 17 of the driving roller 11. By rotating the driving roller 11 and transmitting the rotation, the tension roller 12 and the driven rollers 13 and 14 are driven to rotate, and the photosensitive belt 10 is conveyed in the direction indicated by the arrow in the figure.

  The tension roller 12 is urged by a tension spring 18 to apply tension to the belt photoreceptor 10. In the belt photoconductor driving device 40 according to the present invention, the surface of the driven roller 13 (contact surface with the photoconductor belt 10) installed at a position facing the transfer unit 23 is a SUS roller, and the surface is shot blasted. Thus, a fine unevenness (surface roughness Rmax is 100S) is processed. The code | symbol 19 of FIG. 2 shows a foreign material.

  When a printing experiment of about 5000 pages was performed with the configuration of the present embodiment, even when foreign matter (particularly carrier) was mixed inside the belt photoreceptor 10, the foreign matter was captured in a recess formed on the surface of the driven roller 13, It was possible to prevent the surface of the belt photoreceptor 10 from being pushed up by a foreign substance in the transfer nip portion.

  As a result, poor image quality such as transfer omission was prevented, and high quality image quality was stably obtained for a long period of time.

  In the first embodiment, the configuration in which only the roller having the roughened surface is used as the roller 13 of the transfer unit is shown. However, depending on the roughened state of the roller surface and the material of the roller, the belt photoreceptor 10 easily slips.

  In this configuration, as shown in FIG. 4, the surface of the SUS roller 13 whose surface is roughened (surface roughness Rmax is 200 S) is provided with a Cr plating layer 33 with Ni strike, and the roller 13, the belt photoreceptor 10, and the like. The coefficient of friction was 0.3.

  When a printing experiment of about 5000 pages was performed in the configuration of this example in the same manner as in Example 1, even when foreign matter (particularly carrier) was mixed inside the belt photoreceptor 10, the foreign matter was produced on the surface of the driven roller 13. In addition to preventing the convex surface of the belt photoconductor 10 from being pushed up by foreign matter in the transfer nip, the image quality defect such as transfer omission was prevented, and high quality image quality could be stably obtained.

  In the first embodiment, the configuration in which only the roller whose surface is roughened is used as the roller 13 of the transfer portion is shown. However, in this embodiment, as shown in FIG. The pressing member 15 and the foreign matter storage member 16 are installed on the outer periphery of the outer periphery. By installing the pressing member 15, the foreign matter adhering to the roller surface is scraped off or pushed to the concave portion of the roller surface, and the convex push-up of the surface of the belt photoreceptor 10 by the foreign matter in the transfer nip portion is prevented more efficiently. To do.

  In addition, the foreign matter scraped off by the pressing member 15 is captured by the foreign matter storage member 16 and prevents the foreign matter from reattaching to the inner surface of the belt photoreceptor 10 and each roll surface.

  In the third embodiment, the configuration in which the pressing member is installed on the outer periphery of the surface-roughened driven roller is shown. However, in this embodiment, the pressing member is configured by a permanent magnet 32 as shown in FIG. It is. When the pressing member is the permanent magnet 32, not only foreign matter is captured in the recesses on the roll surface, but also the cleaning effect on the roller surface can be further improved because the carrier and magnetic toner are attracted by the permanent magnet.

  Although the belt photoreceptor driving device and the printing apparatus using the driving device have been described, the present invention can also be applied to an intermediate transfer belt driving device.

It is a schematic block diagram of the belt photoconductor drive device of this invention. (Example 1) It is the perspective view and enlarged view of the belt conveyance roll in this invention. (Example 1) 1 is an overall schematic configuration diagram showing an internal mechanism of a printing apparatus provided with a belt photoreceptor driving device of the present invention. (Example 1) It is a schematic block diagram which shows the belt photoconductor drive device of this invention. (Example 2) It is a schematic block diagram which shows the belt photoconductor drive device of this invention. Example 3 It is a schematic block diagram which shows the belt photoconductor drive device of this invention. (Example 4) It is a schematic block diagram of the conventional belt photoconductor drive device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Belt photoconductor 11 Driving roller 12 Tension roller 13 Belt conveying roll with roughened surface 15 Pressing member 16 Foreign material storage member 32 Permanent magnet 40 Belt photoconductor driving device

Claims (6)

  A driving roller that is provided inside the belt photoconductor and circulates and drives the belt photoconductor, a driven roller that rotates in accordance with the circulation movement of the belt photoconductor, tensions the photoconductor, and circulation of the belt photoconductor A belt photoconductor driving device comprising a tension roller rotating according to movement, wherein the surface roughness Rmax of the drive or driven roller installed at the transfer position is 50S to 200S.   2. The belt photosensitive member driving device according to claim 1, wherein a coefficient of static friction between the driving roller or the driven roller and the belt photosensitive member is 0.2 or more.   2. The belt photosensitive member driving device according to claim 1, wherein a pressing member is provided on an outer periphery of the driving or driven roller.   4. The belt photoconductor driving device according to claim 3, further comprising a foreign material storage member for storing the carrier, toner, dust and the like scraped off by the pressing member.   4. The belt photoreceptor driving device according to claim 3, wherein the pressing member is a permanent magnet. A printing apparatus comprising the belt photoreceptor driving device according to claim 1.

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