Abstract:
There is provided an image forming mechanism including: an image carrier containing a lubricant in a photosensitive layer that is formed on a surface of the image carrier, and on which an electrostatic latent image is formed; a developing section developing the electrostatic latent image into a visible image by a developer that contains the lubricant; and a cleaning member formed with a first layer that contacts the photosensitive layer, and a second layer that is formed of a material having a lower modulus of repulsion elasticity than the first layer and that is layered with the first layer and that does not contact the surface of the image carrier.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 USC 119 from Japanese Patent Application No. 2009-026250 filed on Feb. 6, 2009. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to an image forming mechanism and an image forming device. 
     2. Related Art 
     Conventionally, there are structures that add a lubricant to the surface layer of a photoreceptor so as to reduce wear of the photoreceptor. Further, there are structures that add a lubricant to a developer so as to reduce wear of a photoreceptor. 
     Moreover, there are structures that provide a toner pool so as to aim for increased lifespan of a cleaning blade. Or, there are structures that make a cleaning blade be a two-layer structure. 
     SUMMARY 
     An aspect of the present invention provides an image forming mechanism including: 
     an image carrier containing a lubricant in a photosensitive layer that is formed on a surface of the image carrier, and on which an electrostatic latent image is formed; 
     a developing section developing the electrostatic latent image into a visible image by a developer that contains the lubricant; and 
     a cleaning member formed with a first layer that contacts the photosensitive layer, and a second layer that is formed of a material having a lower modulus of repulsion elasticity than the first layer and that is layered with the first layer and that does not contact the surface of the image carrier. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An exemplary embodiment of the present invention will be described in detail based on the following figures, wherein: 
         FIG. 1  is a cross-sectional view showing the structure of an image forming device equipped with an image forming mechanism relating to an exemplary embodiment of the present invention; 
         FIG. 2  is a side view showing the structure of the image forming mechanism shown in  FIG. 1 ; 
         FIG. 3A  and  FIG. 3B  are side views showing, in an enlarged manner, the structure of the image forming mechanism shown in  FIG. 2 ; 
         FIG. 4  is a cross-sectional view showing the surface structure of a photoreceptor drum relating to the exemplary embodiment of the present invention; 
         FIG. 5  is a structural formula showing the structure of a polymer compound that is a material of a charge transport layer of the photoreceptor drum relating to the exemplary embodiment of the present invention; 
         FIG. 6  is a structural formula showing the structure of a charge transport material that is a material of the charge transport layer of the photoreceptor drum relating to the exemplary embodiment of the present invention; 
         FIG. 7  is a table showing properties of materials forming a cleaning blade relating to the exemplary embodiment of the present invention; 
         FIG. 8  is a graph showing the proportion of the time that the pressing force is 0 of the cleaning blade relating to the exemplary embodiment of the present invention and comparative examples; 
         FIG. 9A  through  FIG. 9D  are graphs showing amounts of irregular wear at the surfaces of photoreceptor drums of the cleaning blade relating to the exemplary embodiment of the present invention and comparative examples; 
         FIG. 10  is a graph showing the relationship between the proportion of the time that the pressing force is 0 and the amount of irregular wear at the surfaces of photoreceptor drums of the cleaning blade relating to the exemplary embodiment of the present invention and comparative examples; 
         FIG. 11A  through  FIG. 11C  are drawings showing, per coefficient of friction, deformation at the surface of the photoreceptor drum, of the cleaning blade relating to the exemplary embodiment of the present invention; 
         FIG. 12  is a graph showing differences in occurrence at a charger of stripes due to contamination, when PTFE and ZnSt are used in a lubricant that is contained in the developer and the surface of the photoreceptor drum relating to the exemplary embodiment of the present invention; and 
         FIG. 13A  and  FIG. 13B  are graphs showing amounts of irregular wear at the surfaces of photoreceptor drums of the cleaning blade relating to the exemplary embodiment of the present invention and a conventional example. 
     
    
    
     DETAILED DESCRIPTION 
     An exemplary embodiment of the present invention will be described hereinafter with reference to the drawings. 
     &lt;Structure&gt; 
       FIG. 1  and  FIG. 2  are cross-sectional views showing the internal structure of an image forming device relating to the exemplary embodiment of the present invention. 
     As shown in  FIG. 1 , an image forming device  10  has an intermediate transfer belt  24  on whose surface toner images are transferred, and image forming mechanisms  30 Y through  30 K that form the toner images on the surface of the intermediate transfer belt  24 . The main portion of the image forming device  10  is structured thereby. 
     Each of the image forming mechanisms  30 Y through  30 K is structured from a photoreceptor drum  12  on whose surface and electrostatic latent image is formed, a charging device  18  for primary charging that contacts and charges the photoreceptor drum  12 , a light scanning device  16  that forms an electrostatic latent image on the photoreceptor drum  12 , and a developing unit  14  that develops the electrostatic latent image by toner. The respective color toners that are consumed in the image formation are replenished by toners  11  of respective colors being supplied from unillustrated toner cartridges to the developing units  14 Y through  14 K. 
     The toner image that is formed on the photoreceptor drum  12  is transferred from the surface of the photoreceptor drum  12  onto the intermediate transfer belt  24  at a nip position between a primary transfer roller  26  that is provided at a position opposing the photoreceptor drum  12  with the intermediate transfer belt  24  nipped therebetween, and the intermediate transfer belt  24  that is driven in the direction of the arrows in the drawing while abutting the photoreceptor drum  12  that rotates. 
     Recording sheets P that are accommodated in a tray  32  are conveyed along a sheet conveying path, and, at a nip position  24 A, are pressed tightly against the intermediate transfer belt  24  that is pressed by a secondary transfer roller  28 . The toner images, that were transferred onto the intermediate transfer belt  24  from the photoreceptor drums  12 , are transferred onto the recording sheet P. 
     The recording sheet P, on whose surface the toner image has been transferred, is conveyed along the conveying path and passes through a fixing device  34  where the heat-fused toner image is fixed. The recording sheet P on which the image is formed is discharged to the exterior of the device and outputted as an image. 
     The internal structure of the periphery of the photoreceptor drum of the image forming device relating to the exemplary embodiment of the present invention is shown in  FIG. 2 . 
     As shown in  FIG. 2 , after surface potential is applied to the photoreceptor drum  12  at the charging device  18 , scanning exposure is provided by the light scanning device  16 . Due to potential being lost only at the exposed portions, an electrostatic latent image is formed on the surface of the photoreceptor drum  12 . Due to the toner  11  being supplied to the non-exposed portions by the developing unit  14 , the electrostatic latent image is developed by the toner, and is formed on the surface of the photoreceptor drum  12  as a toner image  11 A that is formed from the toner  11  of that color. 
     The toner image is transferred by nip pressure and transfer potential onto the intermediate transfer belt  24  that is nipped by the photoreceptor drum  12  at the primary transfer roller  26 . The toner images that are transferred onto the intermediate transfer belt  24  are transferred so as to be superposed at the same position for each color of YMCK, and finally, the toner images of the four colors are superposed at a correctly aligned position and transferred onto the recording sheet P. 
     After the toner image  11 A that is formed on the surface of the photoreceptor drum  11 A is transferred onto the intermediate transfer belt  24 , residual toner  11 B that was not transferred onto the intermediate transfer belt  24  remains on the surface of the photoreceptor drum  12 . As shown in  FIG. 2 , the residual toner  11 B is scraped-off by a cleaning blade  20  and removed from the surface of the photoreceptor drum  12 . 
     The surface structure of the photoreceptor drum  12  is shown in  FIG. 4 . The photoreceptor drum  12  is a structure at which a undercoat layer  12 B, a charge generating layer  12 C and a charge transport layer  12 D are formed on an aluminum substrate  12 A. 
     Specifically, the cylindrical aluminum substrate  12 A of an outer diameter of Φ30 mm that has been subjected to honing processing is readied. A coating liquid for undercoat layer formation is coated on the aluminum substrate  12 A by dipping, and the undercoat layer  12 B is formed by heating and drying. Next, a coating liquid for charge generating layer formation is coated on the undercoat layer  12 B by dipping, and is heated and dried such that the charge generating layer  12 C is formed. Next, a coating liquid for the charge transport layer is obtained by adding and dispersing polytetrafluoroethylene particulates Ruburon L2 (Daikin Industries, Ltd.) to and in a liquid that is obtained by mixing together the charge transport material shown by formula (VI- 1 ) of  FIG. 6 , a polymer compound having the structural unit shown by (VI- 2 ) of  FIG. 5 , and chlorobenzene. This coating liquid for the charge transport layer is coated on the charge generating layer  12 C and heated so as to form the charge transport layer  12 D. 
     The photoreceptor drum  12 , at which the undercoat layer  12 B, the charge generating layer  12 C and the charge transport layer  12 D that contains polytetrafluoroethylene (hereinafter, referred to as PTFE) as described above are formed on the aluminum substrate  12 A that has been subjected to honing processing, is obtained as described above. 
     The structure at the periphery of the cleaning blade of the image forming device relating to the exemplary embodiment of the present invention is shown in  FIG. 3A  and  FIG. 3B . 
     As shown in  FIG. 3A  and  FIG. 3B , the cleaning blade  20  is a two-layer structure. An obverse layer  20 A that contacts the surface of the photoreceptor drum  12  is formed of a material that, as compared with a reverse layer  20 B that does not contact the surface of the photoreceptor drum  12 , has a low Young&#39;s modulus and damping coefficient, high hardness and low repulsion. The cleaning blade  20  is a slender plate-shaped member. As shown in  FIG. 3A , the region from one transverse direction end to part-way along (Lb in the drawing) is fixed to a holding member  21 , such that La that is the free end side is supported so as to be deformable by its own elasticity. La:Lb is approximately 2:1. 
     As shown in  FIG. 3B , plural places in the longitudinal direction of the holding member  21 , that holds the cleaning blade  20 , are fixed by fixing screws  21 A to a frame  23 . The cleaning blade  20  that is held at the holding member  21  is pressed against the surface of the photoreceptor drum  12  at pressing force NF, and deforms by bite-in amount d. Due thereto, the obverse layer  20 A of the cleaning blade  20  contacts the surface of the photoreceptor drum  12  at angle WA. The residual toner  11 B adhering to the surface of the photoreceptor drum  12  is scraped-off by the obverse layer  20 A of the cleaning blade  20 . 
     In the same way as the charge transport layer  12 D of the photoreceptor  12 , PTFE is contained in the toner  11 . Specifically, silica particles of an average particle diameter of 12 nm, silica particles of an average particle diameter of 40 nm, and Ruburon L2 (Daikin Industries, Ltd.) composed of PTFE particles are added to toner cohered particles, and are mixed-together in a Henschel mixer so as to prepare the toner  11 . Due thereto, the toner  11 , that is in a state in which the PTFE particles adhere in a range of a particle diameter of 0.2 to 1 μm to the toner cohered particles, is obtained. 
     The effects that combinations of structures and properties of materials of the cleaning blade of the image forming device relating to the exemplary embodiment of the present invention, have on the surface of the photoreceptor drum  12  are shown in  FIG. 7  through  FIG. 13 . 
     The state of the distal end of the cleaning blade  20  when the coefficient of friction of the cleaning blade  20  and the surface of the photoreceptor drum  12  is large is shown in  FIG. 11A , and when the coefficient of friction is small is shown in  FIG. 11B , and when the coefficient of friction is small and the pressing force NF is substantially 0 is shown in  FIG. 11C . In the state shown in  FIG. 11C , the longitudinal direction both end portions of the surface of the photoreceptor drum  12  are worn more than the central portion as shown in  FIG. 11A  and  FIG. 11B . 
     With examples of combinations of patterns that change in various ways the size and, as properties, the thickness, Young&#39;s modulus, modulus of repulsion elasticity, and density of the reverse layer  20 B when the cleaning blade  20  is made to be two layer structure as compared with two types of conventional examples that have a cleaning blade of a single-layer structure as shown in  FIG. 7 , the results shown in  FIG. 8  are obtained that, with pattern  4 , pattern  7  and pattern  9 , the time that the pressing force NF is substantially 0 is shorter than the conventional examples. It can be understood that, the longer the time that the pressing force NF is substantially 0, the easier it is for the cleaning blade  20  to be excited, and the easier it is for irregular wear to occur at the surface of the photoreceptor drum  12 . Namely, as shown by the graph in  FIG. 10 , the time that the pressing force NF is substantially 0 and the difference in the wear amount in the longitudinal direction at the surface of the photoreceptor drum  12  are correlated. 
     Namely, pattern  4  is a combination in which the Young&#39;s modulus of the reverse layer  20 B is high, and pattern  7  is a combination in which the modulus of repulsion elasticity of the reverse layer  20 B is low, and pattern  9  is a combination in which the density of the reverse layer  20 B is low. In accordance with these combinations, as compared with the conventional examples shown in  FIG. 9A  and  FIG. 9B , results are obtained that there is little occurrence of irregular wear in the longitudinal direction at the surface of the photoreceptor drum  12 , as shown in  FIG. 9C  and  FIG. 9D . 
     The amount of occurrence at the charging device  18  of stripes due to contamination, per number of prints, is shown in  FIG. 12  by comparing two types of lubricants. As shown in  FIG. 12 , results are obtained that, as compared with the example using zinc stearate (ZnSt) in the lubricant contained in the charge transport layer  12 D of the photoreceptor drum  12  and the toner  11 , it is difficult for stripes due to contamination to arise at the charging device  18  in the example using PTFE in the lubricant. 
     Differences in the irregular wear amount at the surface of the photoreceptor drum  12  after processing 100,000 sheets is shown in  FIG. 13A  and  FIG. 13B  by comparing pattern  4  of the present exemplary embodiment shown in  FIG. 7  and a conventional example. As shown in  FIG. 13A  and  FIG. 13B , the results are obtained that, when the amount of the lubricant PTFE that is contained in the charge transport layer  12 D of the photoreceptor drum  12  and the toner  11  is increased, the irregular wear at the surface of the photoreceptor drum  12  increases in the comparative example, whereas, in the present exemplary embodiment, even if the amount of the lubricant PTFE is increased, it is difficult for irregular wear at the surface of the photoreceptor drum  12  to increase. 
     &lt;Others&gt; 
     An exemplary embodiment of the present invention has been described above, but the present invention is not limited in any way to the above-described exemplary embodiment, and can of course be implemented by various aspects within a range that does not deviate from the gist of the present invention. 
     For example, in the above-described exemplary embodiment, the cleaning blade that removes the residual toner from the surface of the photoreceptor drum is given as an example, but the present invention is not limited to the same and can be applied to, for example, a cleaner such as a belt, a roller, or the like.