JP2008076471A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus mounted with a cleaning device which achieves the longer lifetime of a brush roller by evenly suppressing the adhesion and deposition of a residual toner on the inner wall of a casing and a conveyance screw surface and surely restoring the oblique bristles of the brush roller, and can deliver the recovered toner to the outside of the machine. <P>SOLUTION: The image forming apparatus comprises; a cleaning blade which removes the residual toner of the image carrier by abutting on the image carrier; the brush roller which abuts on the image carrier nearer the upstream side of the image carrier than the abutting position of the cleaning blade; the casing which houses the cleaning device disposed in a recovery section for recovering the recovered toner recovered by the cleaning blade in a bottom section; and a conveyance screw which is disposed in the recovery section in order to deliver the recovered toner collected in the recovery section to a developing unit or a waste toner box. The conveyance screw and the brush roller are arranged in a position where bristle tips intrude in contact with or proximity to the screw surface of the conveyance screw. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus equipped with a cleaning device for cleaning an image carrier.

  Residual toner on the image carrier is scraped off by a cleaning blade or a cleaning brush roller of the cleaning device, collected in a recovery unit at the lower part of the housing of the cleaning device, and transported to the outside by a transport screw provided there. Is done.

  However, the collected toner that collects in the collecting unit adheres to and accumulates on the conveying screw and the inner wall of the collecting unit and becomes difficult to be conveyed. In order to solve this problem, as shown in Patent Document 1, an adhering deposit is provided by a scraping member that is installed in parallel with the axis of the conveying screw and is urged against the conveying screw and swinging. There is a way to break down. The scraping member that contacts while swinging is a member processed into a long plate shape with uneven cuts and windows, and it contacts the screw surface and actively disintegrates the deposited toner and improves transportability. This is what I want to mention. However, such a member is difficult to process and has poor durability, and furthermore, the entire screw surface cannot be contacted, and therefore, particularly in a high-temperature and high-humidity environment, a toner adhesion / deposition phenomenon is likely to occur. . As a result, it is considered that the load on the conveying screw increases and the conveyance of the collected toner gradually deteriorates.

Also, as disclosed in Patent Document 2, there is a rubber sheet elastic member that contacts in parallel with the conveying screw so that the deposited deposits are destroyed. Since it is difficult to scrape off, the conveying effect is not sufficient.
JP 2002-278402 A Japanese Patent Laid-Open No. 10-186888

  The present invention eliminates the disadvantages of the prior art, and evenly suppresses the remaining toner from adhering to and accumulating on the inner wall of the housing and the surface of the conveying screw with a simple structure. The roller's slanted hair is raised and reliably recovered to extend the life of the brush roller, and the recovered toner can be sent to the developer as recycled toner or sent to the waste toner box. An object of the present invention is to provide an image forming apparatus equipped with the apparatus.

This object is achieved by the following technical means 1 or 2.
1. In an image forming apparatus having a cleaning device that cleans and collects residual toner on an image carrier, the cleaning device includes:
A cleaning blade that contacts the image carrier and removes residual toner from the image carrier;
A brush roller in contact with the image carrier on the upstream side of the rotation direction of the image carrier relative to the contact position of the cleaning blade;
A housing for housing the cleaning device provided with a collection unit for collecting toner removed by the cleaning blade at the bottom;
A conveying screw provided in the collecting unit for sending the toner collected in the collecting unit to a developing device or a waste toner box;
Have
The image is characterized in that the conveying screw and the brush roller are arranged at a position in which the bristles of the brush roller are in contact with or close to the screw surface from the peak to the valley of the conveying screw. Forming equipment.
2. 2. The image forming apparatus according to claim 1, wherein a length of the bristles is within a height from a peak to a valley of the screw surface.
3. The direction of the circumferential speed of the contact part of the said conveyance screw and the said brush roller is the same direction, The circumferential speed of the said conveyance screw is made larger than the circumferential speed of the said brush roller, The 1 or 2 characterized by the above-mentioned. The image forming apparatus described in 1.

  In the present invention, in the case of a two-component toner, a carrier or paper powder may be mixed in addition to the toner, and in the case of a one-component toner, a paper powder may be mixed. In addition, the remaining residual toner that is collected may be simply referred to as toner or collected toner.

  According to the present invention, the residual toner scraped off from the image carrier by the cleaning blade is carried to the conveyance screw by the sub brush roller that contacts the image carrier on the upstream side and contacts the screw surface of the conveyance screw. And it will be thrown away evenly. At the same time, the toner is stably and reliably sent out of the apparatus by the conveying screw while it is broken so that the deposited deposit around the conveying screw does not grow. Further, since the brush roller which is in contact with the image carrier and is inclined is raised by the conveying screw, the service life is inevitably extended.

  Although embodiments of the present invention will be described, the following description does not limit the technical scope of the claims and the meaning of terms. In addition, the following assertive description in the embodiment of the present invention shows the best mode, and does not limit the meaning or technical scope of the terms of the present invention.

  First, an outline of an image forming apparatus GS for color electrophotography as an image forming apparatus of the present invention equipped with cleaning apparatuses 190 and 190A will be described with reference to FIG.

  This image forming apparatus GS is called a tandem type color image forming apparatus, and arranges image forming units for forming respective color toner images of yellow, magenta, cyan and black along the moving direction of the intermediate transfer member. The color toner images formed on the image carrier of each image forming unit are transferred onto the intermediate transfer member and superimposed, and then transferred onto the recording medium at once.

  In the figure, a document image placed on an image reading device SC arranged at a position occupying the upper portion of the image forming device GS is scanned and exposed by an optical system, read by a line image sensor CCD, and read by the line image sensor CCD. The analog signal subjected to photoelectric conversion is subjected to analog processing, A / D conversion, shading correction, image compression processing, and the like in an image processing unit, and then an image data signal is sent to the exposure optical system 3 serving as an image writing unit.

  The intermediate transfer member includes a drum type and an endless belt type, both of which have the same function. However, in the following description, an endless belt type intermediate transfer member 6 is used as the intermediate transfer member. I will point to it.

  In the drawing, four sets of process units 100 are formed on the peripheral edge of the endless belt-shaped intermediate transfer body 6 for image formation for each color of yellow (Y), magenta (M), cyan (C) and black (K). Are arranged in tandem in the vertical direction along the intermediate transfer belt 6 with respect to the rotational direction of the intermediate transfer belt 6 in the vertical direction indicated by the arrows in FIG. Arranged in order.

  Each of the four process units 100 has a common structure, and each includes a photosensitive drum 1 as an image carrier, a charger 2 as a charging unit, an exposure optical system 3 as an image writing unit, and development. The apparatus 4 and a photoreceptor cleaning device 190 as an image carrier cleaning means.

  The photosensitive drum 1 that is an image carrier is a layer thickness (film thickness) as a photosensitive layer thickness on the outer periphery of a cylindrical base formed of a metallic member such as aluminum having an outer diameter of about 40 to 100 mm. A photoconductive layer of an organic photoreceptor layer (OPC) having a thickness of about 20 to 40 μm is formed. The photosensitive drum 1 is rotated by power from a driving source (not shown) in a direction indicated by an arrow with the conductive layer grounded, for example, at a linear velocity of about 80 to 280 mm / s, preferably 220 mm / s. .

  Around the photosensitive drum 1, an image forming unit including a charger 2 as a charging unit, an exposure optical system 3 as an image writing unit, and a developing device 4 is set as a photosensitive drum indicated by an arrow in the figure. 1 with respect to the rotation direction.

  The charger 2 as a charging unit is attached in close proximity to the photosensitive drum 1 in a direction parallel to the rotation axis of the photosensitive drum 1. The charger 2 includes a discharge wire as a corona discharge electrode that applies a predetermined potential to the organic photoreceptor layer of the photoreceptor drum 1 and is charged by a corona discharge having the same polarity as the toner (in this embodiment, negatively charged). To apply a uniform potential to the photosensitive drum 1.

  An exposure optical system 3 serving as an image writing means rotationally scans laser light emitted from a semiconductor laser (LD) light source (not shown) in a main scanning direction by a rotating polygon mirror (no symbol), and an fθ lens (no symbol). ), Exposure on the photosensitive drum 1 through an electric signal corresponding to the image signal (image writing) through a reflecting mirror (not shown), etc., and corresponding to the original image on the photosensitive layer on the surface of the photosensitive drum 1. An electrostatic latent image is formed.

  The developing device 4 as a developing unit is configured to supply a two-component developer of each color of yellow (Y), magenta (M), cyan (C), or black (K) charged to the same polarity as the charging polarity of the photosensitive drum 1. Each is provided with a developing roller 4a which is a developer carrying member formed of, for example, a cylindrical nonmagnetic stainless steel or aluminum material having a thickness of 0.5 to 1 mm and an outer diameter of 15 to 25 mm. The developing roller 4a is kept in contact with the photosensitive drum 1 with a predetermined gap (for example, 100 to 1000 μm) by an abutting roller (not shown), and rotates in the same direction as the rotational direction of the photosensitive drum 1. At the time of development, a photoconductor drum is applied by applying to the developing roller 4a a DC voltage having the same polarity as the toner (negative polarity in the present embodiment) or a developing bias voltage that superimposes an AC voltage on the DC voltage. The reversal development is performed on the upper exposed portion. As the developer (toner) used for the reversal development, styrene acrylic polymerized toner is used.

The endless belt-shaped intermediate transfer member 6 has a volume resistivity of about 1.0 × 10 ^{7 to} 1.0 × 10 ⁹ Ω · cm and a surface resistivity of 1.0 × 10 ^{10 to} 1.0 × 10 ¹² Ω. / □ About semi-conductive endless (seamless) resin belt members are used, for example, conductive materials for engineering plastics such as modified polyimide, thermosetting polyimide, ethylene tetrafluoroethylene copolymer, polyvinylidene fluoride, nylon alloy, etc. Is a semiconductive resin film substrate having a thickness of 0.05 to 0.5 mm. As the base of the endless belt-shaped intermediate transfer member 6, a semiconductive rubber belt having a thickness of 0.5 to 2.0 mm in which a conductive material is dispersed in silicon rubber or urethane rubber can also be used. The endless belt-shaped intermediate transfer body 6 is wound around a plurality of roller members including a guide roller 6A, a tension roller 6a, and a backup roller 6B facing the secondary transfer roller 7A, and is supported to be rotatable in the vertical direction. It is also possible to use a drum-shaped intermediate transfer member.

  The primary transfer roller 7 serving as a primary transfer unit for each color is made of a roller-like conductive member using foamed rubber such as silicon or urethane, for example, and the photosensitive drum 1 for each color with the endless belt-like intermediate transfer 6 interposed therebetween. The transfer area is formed between the endless belt-like intermediate transfer 6 and the photosensitive drum 1 by pressing the back surface of the endless belt-like intermediate transfer 6. A DC constant current having a polarity opposite to that of the toner (positive polarity in the present embodiment) is applied to the primary transfer roller 7 by constant current control, and a toner image on the photosensitive drum 1 is formed by a transfer electric field formed in the transfer area. The image is transferred onto the endless belt-shaped intermediate transfer body 6.

  The image forming process (image forming process) will be described below.

  When the image recording is started, the photosensitive drum drive motor (not shown) is rotated to rotate the Y photosensitive drum 1 in the direction indicated by the arrow in the figure, and a potential is applied to the Y photosensitive drum 1 by the Y charger 2. . After the Y photosensitive drum 1 is applied with a potential, the Y exposure optical system 3 performs exposure (image writing) with an electrical signal corresponding to the first color signal, that is, the Y image data. An electrostatic latent image corresponding to a yellow (Y) image is formed on the body drum 1. The latent image is reversely developed by the Y developing device 4 to form a toner image made of yellow (Y) toner on the Y photosensitive drum 1. The Y toner image formed on the Y photosensitive drum 1 is transferred onto the endless belt-shaped intermediate transfer body 6 by a primary transfer roller 7 as a primary transfer means.

  Next, a potential is applied to the M photosensitive drum 1 by the M charger 2. After the potential is applied to the M photoconductor drum 1, the M exposure optical system 3 performs exposure (image writing) with an electrical signal corresponding to the first color signal, that is, the M image data, and the M photosensitivity. An electrostatic latent image corresponding to a magenta (M) image is formed on the body drum 1. The latent image is reversely developed by the M developing device 4 to form a toner image made of magenta (M) toner on the M photoconductor drum 1. The M toner image formed on the M photoconductor drum 1 is transferred onto the endless belt-shaped upper intermediate transfer body 6 by being superimposed on the Y toner image by a primary transfer roller 7 as a primary transfer unit.

  By a similar process, a toner image made of cyan (C) toner formed on the C photoconductive drum 1 and a toner image made of black (K) toner formed on the K photoconductive drum 1 are obtained. Sequentially formed on the endless belt-shaped intermediate transfer body 6 in an overlapping manner, and a superimposed color toner image composed of Y, M, C, and K toners is formed on the peripheral surface of the endless belt-shaped intermediate transfer body 6. .

  The toner remaining on the peripheral surface of each photoconductor drum 1 after the transfer is cleaned by a photoconductor cleaning device 190.

  On the other hand, the recording medium P as recording paper accommodated in the paper feed cassettes 20A, 20B, and 20C is fed by the feed roller 21 and the paper feed roller 22A provided in the paper feed cassettes 20A, 20B, and 20C, respectively, and conveyed. A secondary transfer roller serving as a secondary transfer unit that is transported on the path 22 by transport rollers 22B, 22C, and 22D, to which a voltage having a polarity opposite to that of the toner (a positive polarity in this embodiment) is applied via the registration roller 23. The superimposed color toner images (color images) formed on the endless belt-shaped intermediate transfer body 6 are transferred onto the recording medium P in a lump in the transfer area of the secondary transfer roller 7A.

  The recording medium P onto which the color image has been transferred is heated and pressed at a fixing nip portion NA formed by the heating roller 17a and the pressure roller 17b of the fixing device 17 and is fixed by the paper discharge roller 24. It is placed on the outer paper discharge tray 25.

  The above describes the state in which image formation is performed on the first side, which is one side of the recording medium P. In the case of double-sided copying, the sheet discharge switching member 26 is switched, the sheet guiding portion 26A is opened, and recording is performed. The medium P is conveyed in the direction of the broken line arrow.

  Further, the recording medium P is conveyed to the lower conveying path 27B by the conveying mechanism 27A, switched back by the sheet reversing unit 27C, and the conveying path is switched by the branching unit 27D. And is conveyed into the duplex copying paper feed unit 130.

  The recording medium P moves in a paper feeding direction through a conveyance guide 131 provided in the duplex copying paper feeding unit 130, and the recording medium P is re-fed by the paper feeding roller 132 and guided to the conveyance path 22.

  Then, again, as described above, the recording medium P is conveyed in the direction of the secondary transfer roller 7A, the toner image is transferred to the second surface which is the back surface of the recording medium P, fixed by the fixing device 17, and then the paper discharge tray. 25 is discharged.

  Further, the endless belt-shaped intermediate transfer body 6 obtained by separating the curvature of the recording medium P after the color image is transferred onto the recording medium P by the secondary transfer roller 7A as the secondary transfer means is used as the intermediate transfer body cleaning means. The residual toner is removed by the intermediate transfer member cleaning device 190A.

  As described above, there are a photosensitive member and an intermediate transfer member as the image carrier, and in this embodiment, the photosensitive drum 1 is used as the photosensitive member, and an endless belt-like intermediate transfer member 6 is used as the intermediate transfer material member. In the following description regarding the cleaning device, the cleaning device 190 for the photosensitive drum 1 will be mainly described. The configuration of the cleaning device 190A for the endless belt-shaped intermediate transfer member 6 can also be exactly the same as that of the cleaning device except that the image carrier is different.

  A brush roller 192 is used for cleaning residual toner on an image carrier such as the photosensitive drum 1 and the endless belt-shaped intermediate transfer member 6 in the electrophotographic image forming apparatus GS. The brush roller 192 can clean the remaining toner T alone. However, the brush roller can be used as a sub of the main cleaning blade 191. The present invention uses this method. That is, they are arranged as shown in the front view of FIG. 2 and the side view of FIG. Then, as shown in the front view of FIG. 4, the brush roller 192 prevents the residual toner T on the photosensitive drum 1 scraped by the cleaning blade 191 from being returned to the photosensitive drum 1 again. Sub-cleaning is performed by contacting the photosensitive drum 1. At the same time, the brush roller 192 which receives the residual toner T scraped off by the main cleaning blade 191 on the surface and inside of the brush tip portion does not bring the residual toner T close to the surface of the photosensitive drum 1. By rotating in contact with the direction, it is efficiently transported to the transport screw 196 of the recovery unit 193A provided at the bottom of the housing 193 and dropped.

  Further, the brush roller 192 comes into contact with the photosensitive drum 1, and if the toner T is continuously conveyed and sub-cleaning is continued, oblique hairs occur and the outer diameter decreases. If it is left as it is, the contact nip state at the time of initial setting cannot be obtained, and re-attachment due to slipping of the collected toner to the photosensitive drum 1 occurs, and the cleaning property, toner recovery property and durability of the photosensitive drum 1 by the brush roller 192 occur. And the image formed on the recording medium P is also affected and deteriorated.

  However, as shown in the partial side view of FIG. 5, the residual toner T removed by the main cleaning blade 191 is conveyed to the conveying screw 196 while entering the surface of the sub brush roller 192 and the inside of the hair. Here, the hair tip 192A of the brush roller 192 is in contact with or close to the screw surface 196A from the peak to the valley of the conveying screw 196 of the recovery unit 193A, and the screw surface rotates. , The hair tip 192A and the screw surface 196A are repeatedly contacted and separated evenly in order, and the residual toner T is surely wiped off by the conveying screw 196. That is, as shown in the partial side view of FIG. 6, the brush tip 192A is swung while repeatedly contacting and separating from the screw surface 196A and placed on the brush of the brush roller 192 or collected into the brush. The residual toner T therein is wiped off or scraped off and is efficiently fed into the conveying screw 196. The residual toner T is smoothly transported to the outside by the transport screw 196. This is performed without the inconvenience that toner adheres to and accumulates on the inner wall of the recovery unit 193A and the screw surface 196A and causes a conveyance failure. Incidentally, when the brush roller 192 is provided, as shown in the partial side view (a) and the partial front view (b) of FIG. 7, the adhesion and accumulation of the toner T on the inner wall surface of the collecting portion 193A and the screw surface 196A are ensured. In the case where the brush roller 192 is not provided, as shown in the partial side view (a) and the partial front view (b) of FIG. 8, the toner T is applied to the inner wall surface of the recovery unit 193A and the screw surface 196A. Adhesion and accumulation occur in the form of so-called stickiness and lumps (kamakura), and the transport of the collected toner T to the outside of the machine is significantly hindered.

Now, the direction of the peripheral speed at the contact portion of the conveying screw 196 and the brush roller 192, whose axes are arranged in parallel with each other, is the same direction, and the peripheral speed of the conveying screw 196 is greater than the peripheral speed of the brush roller 192. As a result, the bevel of the brush roller 192 is raised so that it is bent in the opposite direction.

  The winding direction of the screw may be determined by the discharging direction. In this way, the raised hair is made and the oblique hair is reliably recovered. Thus, an image forming apparatus GS including a compact, reliable, low-cost and long-life cleaning device can be obtained.

  The endless belt-shaped intermediate transfer member cleaning device 190A shown in FIG. 1 can be configured and operated in the same manner as the photosensitive drum cleaning device 190 as described above, except for the difference in image carrier. Is omitted.

1 is a cross-sectional configuration diagram of a main part of an image forming apparatus including an image carrier cleaning device according to the present invention. FIG. 3 is a front view of a photosensitive drum cleaning device in the image forming apparatus of the present invention. FIG. 3 is a side view of a photosensitive drum cleaning device in the image forming apparatus of the present invention. FIG. 4 is a schematic front view showing a state in which residual toner scraped off from a photosensitive drum is carried in a housing. It is a partial side view which shows the overlap depth of the hair-tip part of a brush roller, and the screw surface of a conveyance screw. FIG. 6 is a diagram illustrating a state in which toner is conveyed while being spilled and dropped onto a screw surface of a conveying screw from a hair tip portion of the brush roller in FIG. 5. FIG. 4A is a partial side view, and FIG. 4B is a partial front view, illustrating a state in which a conveying screw of a collecting unit smoothly conveys toner when a brush roller is provided. It is a figure which shows a mode that the conveyance screw of the collection | recovery part in the case where a brush roller is not provided receives adhesion and the obstruction | occlusion, and becomes impossible to convey, (a) is a partial side view, (b) is a partial front view. .

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging device 3 Exposure optical system 4 Developing apparatus 6 Endless belt-shaped intermediate transfer body 190, 190A Cleaning device 191 Cleaning blade 192 Brush roller 193 Housing 193A Collection part 196 Conveying screw 196A Screw surface GS Image forming apparatus P Recording Medium T Residual toner (collected toner)

Claims (3)

In an image forming apparatus having a cleaning device that cleans and collects residual toner on an image carrier, the cleaning device includes:
A cleaning blade that contacts the image carrier and removes residual toner from the image carrier;
A brush roller in contact with the image carrier on the upstream side of the rotation direction of the image carrier relative to the contact position of the cleaning blade;
A housing for housing the cleaning device provided with a collection unit for collecting toner removed by the cleaning blade at the bottom;
A conveying screw provided in the collecting unit for sending the toner collected in the collecting unit to a developing device or a waste toner box;
Have
The image is characterized in that the conveying screw and the brush roller are arranged at a position in which the bristles of the brush roller are in contact with or close to the screw surface from the peak to the valley of the conveying screw. Forming equipment. The image forming apparatus according to claim 1, wherein a length into which the hair end portion enters is within a height reaching a valley from a peak of the screw surface. The direction of the circumferential speed of the contact part of the said conveyance screw and the said brush roller is the same direction, The circumferential speed of the said conveyance screw is made larger than the circumferential speed of the said brush roller, The Claim 1 or 2 characterized by the above-mentioned. The image forming apparatus described in 1.

Images