JP2010066708A - Process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process cartridge which achieves high image quality over a long term. <P>SOLUTION: The process cartridge includes an electrostatic latent image holding body, a developing means, an electrifying roll which electrifies the electrostatic latent image holding body, an electrifying roll cleaner which comes into contact with a surface of the electrifying roll, and an electrostatic latent image holding body cleaner which cleans a surface of the electrostatic latent image holding body. The electrostatic latent image holding body cleaner includes a cleaning blade, a housing to store collected toner therein, a conveying means to convey the collected toner in the cartridge to the outside, and a discharge port to discharge the collected toner to the outside of the cartridge. Nip width between the electrifying roll and the electrifying roll cleaner is the larger on the discharge port side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a process cartridge.

  Conventionally, as a charging device for an image forming apparatus such as a copying machine or a printer adopting an electrophotographic method, a device using a corona discharge phenomenon such as a scorotron charger has been widely used, but a charging device using a corona discharge phenomenon is used. Then, ozone and nitrogen oxides may be generated. In contrast, the contact charging method in which a conductive charging roll or the like is in direct contact with the photosensitive member to charge the photosensitive member generates less ozone and nitrogen oxides and has good power efficiency. Contact charging is the mainstream.

  In an image forming apparatus using such a contact charging type charging roll, for example, a charging roll cleaner for cleaning the charging roll by rotating in contact with the charging roll is disposed. Further, a process cartridge that can be attached to and detached from the image forming apparatus main body is provided, and a configuration including a photosensitive member, a charging roll, and a charging roll cleaner is disclosed in the process cartridge (see, for example, Patent Document 1). ).

  Further, a method of collecting the transfer residual toner with a cleaning device, returning it to the developing device, and reusing it has been studied. Patent Document 2 discloses an image carrier that carries an electrostatic latent image, and the image carrier. A developer that supplies toner to the electrostatic latent image formed thereon to form a toner image, and a cleaning that removes residual toner remaining on the image carrier after the toner image is transferred onto a transfer material. An image forming apparatus comprising: a device; and a toner conveying screw that conveys the residual toner collected in the housing of the cleaning device to the developing device, wherein a buffer member that contacts an inner wall of the housing is configured to convey the toner. An image forming apparatus characterized by being provided on a screw is disclosed.

JP 2000-162853 A JP 2007-93640 A

  An object of the present invention is to provide a process cartridge capable of achieving high image quality over a long period of time.

The above-described problems of the present invention have been solved by the means described in <1> below. It is described below together with <2> and <3> which are preferred embodiments.
<1> An electrostatic latent image holding body, a developing unit, a charging roll for charging the electrostatic latent image holding body, a charging roll cleaner in contact with the surface of the charging roll, and the electrostatic latent image holding body An electrostatic latent image holding body cleaner for cleaning the surface, the electrostatic latent image holding body cleaner having a cleaning blade, a housing for storing the collected toner, a conveying means for conveying the collected toner in the cartridge to the outside, and A process cartridge having a discharge port for discharging the collected toner to the outside of the cartridge, wherein a nip width between the charging roll and the charging roll cleaner is large on the discharge port side;
<2> The charging roll cleaner is provided with a contact portion made of foamed resin on the outer periphery of the rod-shaped support shaft, the rod-shaped support shaft is arranged in parallel with the conveying auger, and the outer diameter of the contact portion made of foamed resin is The process cartridge according to <1>, which is large on the discharge port side,
<3> The charging roll cleaner is provided with a contact portion made of foamed resin on the outer periphery of the rod-shaped support shaft, and the distance between the rod-shaped support shaft of the charging roll cleaner and the support shaft of the charging roll is determined by the discharge port. The process cartridge according to <1> or <2>, which is small on the side.

According to the invention described in <1>, it is possible to provide a process cartridge capable of forming a high-quality image over a long period of time as compared with the case where the present configuration is not provided.
According to the invention described in <2>, it is possible to provide a simple apparatus as compared with a case where the present configuration is not provided.
According to the invention described in <3>, it is possible to provide a simple apparatus as compared with the case where the present configuration is not provided.

The process cartridge of the present invention includes an electrostatic latent image holding member, a developing unit, a charging roll that charges the electrostatic latent image holding member, a charging roll cleaner that contacts a surface of the charging roll, and the electrostatic latent image. An electrostatic latent image holding body cleaner for cleaning the surface of the image holding body, and the electrostatic latent image holding body cleaner conveys a cleaning blade, a housing for storing the collected toner, and the collected toner in the cartridge to the outside. It has a discharge means for discharging the conveying means and the collected toner to the outside of the cartridge, and the nip width between the charging roll and the charging roll cleaner is large on the discharge port side.
Hereinafter, this embodiment will be described in detail with reference to the drawings. In the following description, the same reference numeral represents the same object.

FIG. 1 is a schematic configuration diagram illustrating an entire image forming apparatus 1 including a process cartridge according to the present embodiment.
The image forming apparatus 1 is a digital color printer, and image data sent from an exposure apparatus for a document (not shown), a personal computer, or the like is sent to the image processing apparatus 12 and subjected to predetermined image processing. Image data that has been subjected to predetermined image processing by the image processing device 12 is also processed by the image processing device 12 into 4 of yellow (Y), magenta (M), cyan (C), and black (K) (each 8 bits). As described below, the image forming units 13Y, 13M, 13C for each color of yellow (Y), magenta (M), cyan (C), and black (K) are converted into color original reproduction color material gradation data. It is sent to the 13K exposure device 14. In this exposure device 14, image exposure with laser light LB is performed in accordance with document reproduction color material gradation data of a predetermined color.
Inside the image forming apparatus 1, four image forming units 13Y, 13M, 13C, and 13K of yellow (Y), magenta (M), cyan (C), and black (K) are spaced at a constant interval in the horizontal direction. Are arranged in parallel. These four image forming units 13Y, 13M, 13C, and 13K are all configured in the same manner, and the electrostatic latent image holding member (photosensitive drum) 15 that is driven to rotate and the surface of the photosensitive drum 15 are arranged. A charging roll 16 that is uniformly charged, an exposure device 14 that exposes an image corresponding to a predetermined color on the surface of the photosensitive drum 15 to form an electrostatic latent image, and a static image formed on the photosensitive drum 15. A developing unit 17 that develops the electrostatic latent image with toner of a predetermined color, a cleaning device 18 that cleans the surface of the photosensitive drum 15, and a charging roll cleaner 60 that cleans the charging roll 16 are configured.

  The exposure device 14 is configured in common to the four image forming units 13Y, 13M, 13C, and 13K, and modulates four semiconductor lasers (not shown) in accordance with the original reproduction color material gradation data of each color. Laser light LB-Y, LB-M, LB-C, and LB-K are emitted from the semiconductor laser in accordance with the gradation data. Of course, the exposure device 14 may be individually configured for each of a plurality of image forming units. The laser beams LB-Y, LB-M, LB-C, and LB-K emitted from the semiconductor laser are irradiated to the polygon mirror 19 through an f-θ lens (not shown), and are deflected and scanned by the polygon mirror 19. The The laser beams LB-Y, LB-M, LB-C, and LB-K deflected and scanned by the polygon mirror 19 pass through an imaging lens (not shown) and a plurality of mirrors to an exposure point on the photosensitive drum 15. Then, scanning exposure is performed obliquely from below.

  Since the exposure device 14 scans and exposes an image on the photosensitive drum 15 from below, the exposure device 14 includes the developing units 17 of four image forming units 13Y, 13M, 13C, and 13K positioned above. There is a risk that toner etc. may fall off and be contaminated. Therefore, the periphery of the exposure apparatus 14 is hermetically sealed by a rectangular parallelepiped frame 20, and four laser beams LB-Y, LB-M, LB-C, and LB-K are applied to the upper portion of the frame 20. Transparent glass windows 21Y, 21M, 21C, and 21K as shield members are provided for exposure on the photosensitive drums 15 of the image forming units 13Y, 13M, 13C, and 13K.

  From the image processing device 12, an exposure device 14 is provided in common for the image forming units 13Y, 13M, 13C, and 13K for each color of yellow (Y), magenta (M), cyan (C), and black (K). The image data of each color is sequentially output. Laser beams LB-Y, LB-M, LB-C, and LB-K emitted from the exposure device 14 in accordance with image data are scanned and exposed on the surface of the corresponding photosensitive drums 15 to form an electrostatic latent image. Is done. The electrostatic latent image formed on the photoconductor drum 15 is developed by toners of yellow (Y), magenta (M), cyan (C), and black (K), respectively, by developing units 17Y, 17M, 17C, and 17K. Developed as an image.

  The yellow (Y), magenta (M), cyan (C), and black (K) toner images sequentially formed on the photosensitive drums 15 of the image forming units 13Y, 13M, 13C, and 13K On the intermediate transfer belt 25 of the transfer unit 22 arranged over the image forming units 13Y, 13M, 13C, and 13K, the images are transferred in multiple by the four primary transfer rolls 26Y, 26M, 26C, and 26K. These primary transfer rolls 26Y, 26M, 26C, and 26K are disposed on the back side of the intermediate transfer belt 25 corresponding to the photosensitive drums 15 of the image forming units 13Y, 13M, 13C, and 13K. A transfer bias power source (not shown) is connected to the primary transfer rolls 26Y, 26M, 26C, and 26K, and a transfer bias having a polarity opposite to a predetermined toner polarity (positive polarity in the present embodiment) is set at a predetermined timing. Applied.

  The intermediate transfer belt 25 is wound around the drive roll 27, the tension roll 24, and the backup roll 28 with a constant tension, and is rotated by a motor (not shown) by a drive roll 27 shown in the drawing. Circulation is driven around at a predetermined speed.

  The yellow (Y), magenta (M), cyan (C), and black (K) toner images transferred onto the intermediate transfer belt 25 in a multiple manner are transferred to the backup roll 28 by a secondary transfer roll 29. The recording sheet 30 that has been secondarily transferred onto a recording medium (recording sheet) 30 as a sheet and onto which the toner images of these colors have been transferred is conveyed to a fixing device 31 positioned above. The secondary transfer roll 29 is in pressure contact with the side of the backup roll 28 and is configured to secondary-transfer toner images of each color onto a recording paper 30 that is conveyed from below to above. The fixing device 31 includes a heating roll 56 heated to a predetermined temperature, and a pressure roll 58 pressed against the heating roll 56. The recording paper 30 onto which the toner images of the respective colors have been transferred undergoes a fixing process by heat and pressure at the pressure contact portion between the heating roll 56 and the pressure roll 58, and is then placed on the upper portion of the image forming apparatus 1 by the discharge roll 32. The paper is discharged onto a provided discharge tray 33.

  The recording paper 30 having a predetermined size from the paper feed cassette 34 is once transported to a registration roll 38 via a paper transport path 37 by a paper feed roller 35 and a pair of paper separating and transporting rollers 36 and stopped. . The paper transport path 37 of the fed recording paper 30 is directed upward in the vertical direction. The recording paper 30 supplied from the paper feed cassette 34 is sent to the secondary transfer position of the intermediate transfer belt 25 by a registration roll 38 that rotates at a predetermined timing.

  When the image forming apparatus 1 makes a full-color double-sided copy, the recording sheet 30 having an image fixed on one side is not directly discharged onto the discharge tray 33 by the discharge roll 32 but is not shown. To switch the transport direction and transport the paper to the duplex transport unit 40 via the pair of paper transport rollers 39. In the double-sided conveyance unit 40, the recording paper 30 is conveyed again to the registration roll 38 with the pair of conveyance rollers (not shown) provided along the conveyance path 41 being reversed. Then, after the image is transferred and fixed on the back surface of the recording paper 30, it is discharged onto the discharge tray 33.

  Further, residual toner, paper dust, and the like are removed from the surface of the photosensitive drum 15 after the toner image transfer process is completed by the cleaning device 18 to prepare for the next image forming process. The cleaning device 18 includes a cleaning blade (not shown), and removes residual toner, paper dust, and the like on the photosensitive drum 15 by the cleaning blade.

  Further, residual toner, paper dust, and the like are removed from the surface of the intermediate transfer belt 25 after the toner image transfer process is completed by the cleaning device 43 to prepare for the next image forming process. The cleaning device 43 includes a cleaning brush 43a and a cleaning blade 43b, and residual toner and paper dust on the intermediate transfer belt 25 are removed by the cleaning brush 43a and the cleaning blade 43b.

  In addition, toner cartridges 44Y, 44M, 44C, and 44K that store yellow, magenta, cyan, and black toners are respectively provided in the upper part of the inside of the image forming apparatus 1. The color toner is supplied.

  Further, a manual feed tray 47 capable of stacking arbitrary sheets is attached to the side surface (left side surface in FIG. 1) of the image forming apparatus 1. A recording paper 52 as a sheet is set on the manual feed tray 47, and the recording paper 52 is fed by a paper feed roller 54 and conveyed to the registration roll 38. The recording sheet 52 is different in type and size from the recording sheet 30 described above.

  FIG. 2 is a schematic cross-sectional view showing the process cartridge of this embodiment, and FIGS. 3 and 4 are schematic plan views showing the process cartridge. The process cartridge is a so-called CRU (Customer Replace Unit), which is a unit that can be replaced by assembling an electrostatic latent image holding member (photosensitive member), which is a consumable part, a developing device, and the like.

The process cartridge 100 is charged with an electrostatic latent image holding member (hereinafter also referred to as “photosensitive member”) 101 that forms a latent image on the surface by exposure from an exposure unit (not shown), and the electrostatic latent image holding member 101. A charging roll 102 to be developed, a developing unit 104 for forming a toner image corresponding to the latent image formed on the electrostatic latent image holding member 101, and an electrostatic latent for removing residual toner on the electrostatic latent image holding member after transfer. An image carrier cleaner (hereinafter also referred to as “photoreceptor cleaner”) 105 is included. Further, the process cartridge 100 has a charging roll cleaner 103 that contacts the surface of the charging roll 102 and removes residual toner on the charging roll 102. The photoreceptor 101, the charging roll 102, the photoreceptor cleaner 105, the charging roll cleaner 103, and the developing device 104 are accommodated in a housing (not shown).
The photoconductor cleaner 105 is provided with a cleaning blade 106 at a position where it contacts the photoconductor 101, and the transfer residual toner 110 remaining on the photoconductor 101 without being transferred is scraped off at the edge of the cleaning blade 106. The transfer residual toner 110 scraped off is collected in the housing 107.
The transfer residual toner 110 collected in the housing 107 and becomes the collected toner 111 is conveyed to the discharge port 109 by the conveying means 108.

As the conveying means 108, a conveying auger can be exemplified, and the conveying auger is a cylindrical member whose surface is formed into a screw shape, and when this is rotated, as shown in FIG. Then, the recovered toner 111 is conveyed in the discharge direction (the direction of arrow D in FIG. 3).
The discharged collected toner 111 may be transported to the developing device 104 and reused.

  In this embodiment, the nip width (contact width) between the charging roll 102 and the charging roll cleaner 103 is large on the discharge port side. In FIG. 3, the charging roll cleaner 103 has a larger outer diameter on the discharge port side. Further, in FIG. 4, the distance between the rod-shaped support shaft 120 of the charging roll cleaner 103 and the support shaft 122 of the charging roll 102 is small on the discharge port side. Although the cleaning blade 106 and the photosensitive member 101, the photosensitive member 101 and the charging roll 102, and the charging roll 102 and the charging roll cleaner 103 are arranged in contact with each other, for convenience of explanation, FIG. 3A and FIG. In FIG. 4 (a), they are shown separately. Moreover, in FIG.3 (b) and FIG.4 (b), the nip part is shown with the dotted line.

Referring to FIG. 3, the charging roll cleaner 103 is provided with a contact portion 121 made of foamed resin on the outer periphery of a rod-shaped support shaft 120, and the rod-shaped support shaft 120 includes a conveying means (conveying auger) 108 and a charging roll. 102, arranged in parallel with the photoconductor 101.
In FIG. 3, when the outer diameter of the contact portion 121 on the discharge port side is s and the outer diameter on the opposite side of the discharge port is t, s> t.

The difference between the outer diameter s and the outer diameter t is preferably 1 mm or more and 10 mm or less, more preferably 1 mm or more and 8 mm or less, and further preferably 2 mm or more and 6 mm or less.
As shown in FIG. 3B, when the charging roll cleaner 103 having a large outer diameter on the discharge port side of the contact portion 121 is brought into contact with the charging roll 102, the nip width on the discharge port side is opposite to the discharge port. Larger than the nip width.
5 is a cross-sectional view of the charging roll 102 and the charging roll cleaner 103 in FIG. 3, FIG. 5 (b) is a cross-sectional view on the discharge port side, and FIG. 5 (a) is a side opposite to the discharge port. It is sectional drawing.
3 and 5, the outer periphery s on the discharge port side of the charging roll cleaner 103 is larger than the outer periphery t on the side opposite to the discharge port. Further, the distance between the shaft-shaped support shaft 120 of the charging roll cleaner 103 and the support shaft 122 of the charging roll 102 is the same (x = y) on the discharge port side and the opposite side to the discharge port. The nip width on the discharge port side (a in FIG. 5B) is larger than the nip width on the side opposite to the discharge port (b in FIG. 5A). That is, a> b is established. The difference between a and b is preferably 0.5 mm or more and 5 mm or less. When the difference between a and b is within the above range, even if the nip width of b is increased, the nip width of a can be suppressed to a small value. This is preferable because adhesion of additives and the like can be prevented.
Here, b is preferably 1 mm or more and 7 mm or less. When b is in the above range, the nip width of a can be suppressed small, and the toner and external additive can be prevented from sticking to the contact charging roll accompanying excessive increase of the nip width.
The configuration shown in FIG. 3 can be obtained by using the charging roll cleaner 103 having a large outer diameter on the discharge port side instead of the conventional charging roll cleaner.

In the embodiment shown in FIG. 4, the inter-axis distance between the rod-shaped support shaft 120 of the charging roll cleaner 103 and the support shaft 122 of the charging roll 102 is small on the discharge port side. In FIG. 4, the inter-axis distance on the discharge port side is represented by x, and the inter-axis distance on the side opposite to the discharge port is represented by y, where x <y.
6 is a cross-sectional view of the charging roll 102 and the charging roll cleaner 103 in FIG. 4, FIG. 6 (b) is a cross-sectional view on the discharge port side, and FIG. 6 (a) is opposite to the discharge port. It is sectional drawing by the side.
4 and 6, the outer periphery s on the discharge port side of the charging roll cleaner 103 is equal to the outer periphery t on the opposite side of the discharge port side (t = s). Further, when the distance between the shafts of the rod-shaped support shaft 120 of the charging roll cleaner 103 and the support shaft 122 of the charging roll 102 on the discharge port side is x, and the distance between the axes on the opposite side to the discharge port side is y, x <y.
Thereby, the nip width on the discharge port side (a in FIG. 6B) becomes larger than the nip width on the side opposite to the discharge port (b in FIG. 6A). That is, a> b is established. The preferred range of the difference between a and b and the preferred range of b are the same as above.

Next, the operation of the present invention will be described in detail.
When image formation with a high image density is performed for a long period of time, the amount of the collected toner 111 in the housing 107 increases, and the collected toner 111 stays in the vicinity of the discharge port 109. When such a phenomenon occurs, the collected toner 111 re-transfers to the photoconductor 101 and the photoconductor 101 is contaminated. Further, there is an imbalance between the photosensitive member 101 and the cleaning blade 106 in which the amount of toner intervening increases and the amount of intervening increases particularly on the discharge port side.
According to the present inventor, such an imbalance in the amount of toner involved destabilizes the blade behavior of the cleaning blade 106, causing contamination of the charging roll 102 via the photosensitive member 101, resulting in image deterioration due to uneven charging. I found that the problem arises.

  In the process cartridge of this embodiment, the nip width (contact width) between the charging roll 102 and the charging roll cleaner 103 is increased on the discharge port 109 side, so that the cleaning property of the charging roll 103 is improved on the discharge port side. It suppresses the imbalance of the amount and forms a good image over a long period of time.

(Charging roll cleaner)
Details of the charging roll cleaner will be described. The charging roll cleaner can be appropriately selected from known charging roll cleaners, and is not particularly limited. Examples of the charging roll cleaner include a contact portion (sponge layer) made of foamed resin formed on the outer periphery of a rod-shaped support shaft (shaft). it can.
As the material of the shaft of the charging roll cleaner, free-cutting steel, stainless steel, etc. are used, and the material and surface treatment method are appropriately selected according to the application such as slidability. The conductive treatment may be performed by a general treatment such as a plating treatment, or may be used as it is. In addition, since the charging roll cleaner comes into contact with the charging roll through a sponge layer at an appropriate nip pressure, a material that does not bend at the time of nip or a shaft diameter that is sufficiently rigid with respect to the shaft length is selected. The

  The contact portion (sponge layer) is made of a foam having a porous three-dimensional structure, and preferably has a cavity or an uneven portion (hereinafter referred to as a cell) inside or on the surface and has elasticity. . This sponge layer is selected from polyurethane, polyethylene, polyamide, olefin, melamine or polypropylene, NBR, EPDM, natural rubber and styrene butadiene rubber, chloroprene, silicone, nitrile, etc. The Thereby, the sponge layer which has many cells can be manufactured cheaply. The sponge layer efficiently cleans foreign substances such as external additives by driven sliding rubbing with the charging roll, and at the same time does not damage the surface of the charging roll due to rubbing of the sponge layer. In order to prevent breakage, polyurethane that is strong in tearing, tensile strength, etc. is particularly preferably used.

  It is not particularly limited as polyurethane, but polyol such as polyester polyol, polyether polyester and acrylic polyol, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4-diphenylmethane diisocyanate, tolidine diisocyanate, It only needs to be accompanied by a reaction of an isocyanate such as 1,6-hexamethylene diisocyanate, and a chain extender such as 1,4-butanediol or trimethylolpropane is preferably mixed. In general, foaming is performed using a foaming agent such as water, azodicarbonamide, azo compounds such as azobisisobutyronitrile. Further, auxiliary agents such as foaming aids, foam stabilizers, catalysts, etc. may be added as necessary.

  As shown in FIG. 3, in order to increase the outer diameter on the discharge port side, a method of cutting after foaming can be exemplified.

  The outer diameter of the charging roll cleaner is not particularly limited, but is preferably from 7 mm to 14 mm, more preferably from 8 mm to 13 mm, and the thickness of the sponge layer is preferably from 2 mm to 4 mm. When the diameter is 14 mm or less, it is preferable from the viewpoint of miniaturization, and when the diameter is 7 mm or more, the number of times of contact with the external additive per place on the peripheral surface is small, and the number of cleanings is small, so that long-term stability is excellent. .

(Charging roll)
Next, details of the charging roll will be described. The charging roll may be appropriately selected from known charging rolls, and is not particularly limited. Examples thereof include a conductive elastic layer and a surface layer sequentially formed as a charging layer on a conductive support shaft (shaft).
The outer diameter (diameter) of the charging roll is not particularly limited, but is preferably from 7 mm to 15 mm, and more preferably from 8 mm to 14 mm. A diameter of 15 mm or less is advantageous from the viewpoint of miniaturization. When the diameter is 7 mm or more, the number of times of contact with the external additive per place on the peripheral surface is small, and the number of discharges is small, which is advantageous for long-term stability.

The charging roll is not limited to the following configuration as long as it has a predetermined charging performance.
As the material of the spindle (shaft), free-cutting steel, stainless steel, etc. are used, and the material and surface treatment method are appropriately selected according to the application such as slidability. The conductive process is performed by a general process.

  The conductive elastic layer constituting the charging layer of the charging roll is, for example, an elastic material such as rubber having elasticity, a conductive material such as carbon black or ionic conductive material that adjusts the resistance of the conductive elastic layer, and as necessary. Materials that can usually be added to rubber, such as softeners, plasticizers, curing agents, vulcanizing agents, vulcanization accelerators, anti-aging agents, fillers such as silica and calcium carbonate, may be added. It is formed by coating a peripheral surface of a conductive shaft with a mixture added with materials usually added to rubber. As a conductive agent for the purpose of adjusting the resistance value, a material in which a material that conducts electricity using electrons and / or ions as a charge carrier, such as carbon black or an ionic conductive agent blended in a matrix material, is used. it can. The elastic material may be a foam.

  The elastic material constituting the conductive elastic layer is formed, for example, by dispersing a conductive agent in a rubber material. Rubber materials include isoprene rubber, chloroprene rubber, epichlorohydrin rubber, butyl rubber, urethane rubber, silicone rubber, fluorine rubber, styrene-butadiene rubber, butadiene rubber, nitrile rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide copolymer Examples thereof include rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, ethylene-propylene-diene terpolymer rubber (EPDM), acrylonitrile-butadiene copolymer rubber, natural rubber, and blend rubbers thereof. Among these, silicone rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, acrylonitrile-butadiene copolymer rubber and blended rubber thereof are preferably used. These rubber materials may be foamed or non-foamed.

  As the conductive agent, an electronic conductive agent or an ionic conductive agent is used. Examples of the electronic conductive agent include carbon black such as ketjen black and acetylene black; pyrolytic carbon, graphite; various conductive metals or alloys such as aluminum, copper, nickel, stainless steel; tin oxide, indium oxide, titanium oxide Examples thereof include fine powders such as various conductive metal oxides such as tin oxide-antimony oxide solid solution and tin oxide-indium oxide solid solution; Examples of ionic conductive agents include perchlorates and chlorates such as tetraethylammonium and lauryltrimethylammonium; alkali metals such as lithium and magnesium; perchlorates and chlorates of alkaline earth metals Can be mentioned. Among them, the electronic conductive agent is preferable from the viewpoint of maintainability because it has little adhesion to the charging roll cleaner.

  The surface layer constituting the charging layer is formed to prevent contamination by foreign matters such as toner, and the material of the surface layer may be any of resin, rubber, etc. Is not to be done. Polyester, polyimide, copolymer nylon, silicone resin, acrylic resin, polyvinyl butyral, ethylene tetrafluoroethylene copolymer, melamine resin, fluoro rubber, epoxy resin, polycarbonate, polyvinyl alcohol, cellulose, polyvinylidene chloride, polyvinyl chloride, polyethylene And ethylene vinyl acetate copolymer. Of these, polyvinylidene fluoride, a tetrafluoroethylene copolymer, polyester, polyimide, and copolymer nylon are preferably used from the viewpoint of resistance to external additives.

  The surface layer can contain a conductive material to adjust the resistance value. The conductive material preferably has a particle size of 3 μm or less. In addition, as a conductive agent for the purpose of adjusting the resistance value, it electrically conducts electrons and / or ions as charge carriers, such as carbon black, conductive metal oxide particles, or ionic conductive agent blended in the matrix material. What disperse | distributed material etc. can be used.

  Further, it is preferable to use a fluorine-based or silicone-based resin for the surface layer. In particular, it is preferably composed of a fluorine-modified acrylate polymer. Further, fine particles may be added to the surface layer. As a result, the surface layer becomes hydrophobic and acts to prevent the adhesion of foreign matter to the charging roll. In addition, insulating particles such as alumina and silica are added to give unevenness to the surface of the charging roll, reducing the load during rubbing with the photoreceptor and reducing the wear resistance between the charging roll and the photoreceptor. It is also possible to improve the performance.

  Hereinafter, the present embodiment will be described in more detail with reference to examples, but the present embodiment is not limited thereto.

Example 1
In Example 1, the process cartridge shown in FIGS. 3 and 5 was used.
Here, the outer diameter s on the discharge port side of the charging roll cleaner was φ14 mm, and the outer diameter s on the side opposite to the discharge port was φ10 mm. Further, the distance between the rod-shaped support shaft of the charging roll cleaner and the support shaft of the charging roll was 11.5 mm.
Further, the outer diameter of the charging roll was fixed at 14 mm.

(Example 2)
In Example 2, the process cartridge shown in FIG. 4 was used.
Here, the outer diameter of the charging roll cleaner was constant at 10 mm. Further, the distance between the rod-shaped support shaft of the charging roll cleaner and the support shaft of the charging roll was set to x = 10.5 mm on the discharge port side and y = 11.5 mm on the opposite side to the discharge port.
Further, the outer diameter of the charging roll was fixed at 14 mm.

(Comparative Example 1)
In Comparative Example 1, the process cartridge shown in FIG. 7 was used.
Here, the outer diameter of the charging roll cleaner is constant at 10 mm, and the distance between the rod-shaped support shaft of the charging roll cleaner and the support shaft of the charging roll is fixed at 11.5 mm.
The outer diameter of the charging roll is constant at φ14 mm.

(Evaluation methods)
As shown in Examples 1 and 2 and Comparative Example 1, processing was performed so that a charging roll cleaner could be installed in DocuCentre Color 450 manufactured by Fuji Xerox Co., Ltd.
Halftone image of 20,000 sheets in total, 10,000 sheets of A4 horizontal under high temperature and humidity of 28 ° C and 85% humidity, and 10,000 sheets of A4 horizontal under low temperature and low humidity of 10 ° C / humidity of 15%. After forming, a halftone image was formed under low temperature and low humidity, and the image quality was evaluated.
The nip width was measured with a three-dimensional measuring device.
The results are shown in the table below.

1 is a schematic configuration diagram illustrating an entire image forming apparatus including a process cartridge according to an exemplary embodiment. It is a cross-sectional schematic diagram which shows the structure of the process cartridge of this embodiment. FIG. 3 is a schematic plan view illustrating an example of a process cartridge according to the present embodiment. It is a plane schematic diagram which shows another example of the process cartridge of this embodiment. It is a cross-sectional schematic diagram which shows an example of the contact of the charging roll and charging roll cleaner of the process cartridge of this embodiment. It is a cross-sectional schematic diagram which shows another example of the contact of the charging roll and charging roll cleaner of the process cartridge of this embodiment. It is a plane schematic diagram which shows the process cartridge of a comparative example. s

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 12 Image processing apparatus 13Y Yellow image forming unit 13M Magenta image forming unit 13C Cyan image forming unit 13K Black image forming unit 14 Exposure apparatus 15 Electrostatic latent image holding body (photosensitive drum)
16 Charging roll 17 Developer 18 Cleaning device 19 Polygon mirror 20 Frame 21Y, 21M, 21C, 21K Window 22 Transfer unit 24 Tension roll 25 Intermediate transfer belt 26Y, 26M, 26C, 26K Primary transfer roll 27 Drive roll 28 Backup roll 29 Two Next transfer roll 30 Recording medium (recording paper)
Reference Signs List 31 Fixing Unit 32 Discharge Roll 33 Discharge Tray 34 Paper Feed Cassette 35 Paper Feed Roller 36 Paper Separation and Conveyance Roller Pair 37 Paper Conveyance Path 38 Resist Roll 39 Paper Conveyance Roller Pair 40 Double Side Conveyance Unit 41 Conveyance Path 43 43a Cleaning brush 43b Cleaning blade 44Y, 44M, 44C, 44K Toner cartridge 47 Manual feed tray 52 Recording paper 54 Paper feed roller 56 Heating roll 58 Pressure roll 60 Charging roll cleaner 100 Process cartridge 101 Electrostatic latent image holder (photoconductor)
102 Charging roll 103 Charging roll cleaner 104 Developer 105 Electrostatic latent image carrier cleaner (photoconductor cleaner)
106 Cleaning blade 107 Housing 108 Conveying means 109 Discharge port 110 Transfer residual toner 111 Recovered toner 112 Screw-like protrusion 120 Rod-like support shaft 121 Contact portion 122 Support shaft LB of charging roll Laser beam

Claims (3)

An electrostatic latent image carrier;
Developing means;
A charging roll for charging the electrostatic latent image holding member;
A charging roll cleaner in contact with the surface of the charging roll;
An electrostatic latent image carrier cleaner for cleaning the surface of the electrostatic latent image carrier;
The electrostatic latent image holder cleaner has a cleaning blade, a housing for storing the collected toner, a conveying means for conveying the collected toner in the cartridge to the outside, and a discharge port for discharging the collected toner to the outside of the cartridge,
A process cartridge, wherein a nip width between the charging roll and the charging roll cleaner is large on a discharge port side.   2. The process cartridge according to claim 1, wherein the charging roll cleaner is provided with an abutting portion made of foamed resin on an outer periphery of the rod-shaped support shaft, and an outer diameter of the abutting portion made of foamed resin is large on the discharge port side. .   The charging roll cleaner is provided with a contact portion made of foamed resin on the outer periphery of the rod-shaped support shaft, and the distance between the shaft-shaped support shaft of the charging roll cleaner and the support shaft of the charging roll is small on the discharge port side. The process cartridge according to claim 1 or 2.

Images