JP2883921B2 - Cleaning device for image forming apparatus - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning apparatus for an image forming apparatus using a toner for developing an electrostatic latent image such as an electrophotographic copying machine, a printer, and a facsimile, and more particularly, to a cleaning apparatus. The present invention relates to a cleaning device for an image forming apparatus, comprising a cleaning unit and a brush for a toner disturber disposed upstream thereof.

[Conventional technology]

Recently, an organic photoconductor called OPC has been used in electrophotographic copying machines instead of an inorganic photoconductor such as selenium. As shown in FIG. 12 (a), the OPC photoreceptor has an undercoat layer UCU, a charge generation layer CGL, and a charge transport layer CTL sequentially provided on a conductive substrate CB.
As shown in FIG. 12 (b), there is a two-layer structure in which a charge generation layer CGL and a charge transport layer CTL are provided in this order on a conductive substrate CB. is there. The undercoat layer UCL and the charge generation layer CGL usually have a thickness of 1 μm or less, and the charge transport layer CTL has a thickness of 10 to 30 μm. Of these layers, the charge transport layer CTL, which is in direct contact with the cleaning member and the developing member, is an organic material, and is generally fragile and easily worn. The causes of the wear include the development system and the contact with the copy paper, but the cleaning member (blade, fur brush) is the largest. For this reason, a binder polymer that is hard to be worn and hard to be damaged is selected in addition to electric characteristics such as charging property and ozone resistance. Generally, polycarbonate resin, polyester resin, methacrylic resin and the like are used.

The sensitivity of such a stacked OPC photoreceptor depends on the carrier generation efficiency in the charge generation layer CGL and the charge transport layer CTL
And the mobility of carriers in the charge transport layer CTL. In order to increase the sensitivity, a charge generation layer CGL material with high carrier generation efficiency,
It is necessary to combine a charge generation layer CGL material having a large carrier mobility with a charge transport layer CTL material having good compatibility. To stabilize the sensitivity, it is important that the carrier generation efficiency, carrier mobility, and carrier injection efficiency have little dependence on an electric field or temperature. By the way, the carrier generation efficiency and the carrier injection efficiency are generally low in the low electric field region of the light portion potential level, but there are some photoconductors which are hardly reduced depending on the type of the photoconductor. In the case of such a photoreceptor, the light-portion potential may increase due to abrasion of the charge transport layer CTL due to a cleaning system or the like, causing background fog or the like (that is, a change in sensitivity). A brief description will be given of a mechanism in which the fogging of the background portion occurs due to the decrease in the thickness of the charge transport layer CTL. When corona discharge occurs on the photoreceptor, the photoreceptor is charged by the charge on the photoreceptor surface. Assuming that the charge per unit area on the photoreceptor is Q and the capacitance per unit area of the photoreceptor is C, a relationship of Q = CV −− is established between these and the surface potential V. Assuming that the relative permittivity of the photoconductor is ε, the permittivity of vacuum is ε ₀ , and the thickness of the photoconductor (which is almost equivalent to the thickness of the charge transport layer CTL) is 1, the capacitance C is C per unit area. = Ε · ε ₀ / l −− From the formula, Q = ε · ε ₀ · V / l −− In the formula, as described above, the charge transport layer CTL
Let us consider a case where the film thickness worn by the cleaning system or the like is reduced. When the charging potential V is kept substantially constant irrespective of the film thickness by the scorotron, the amount of charge Q on the surface of the photoreceptor is expressed by a formula, which is a linear expression which is the reciprocal of the film thickness 1 of the charge transport layer CTL. The thinner the film thickness, the larger the amount of charge Q on the surface. At a light potential portion level, when a certain amount of light (exposure amount) is incident, more exposure is needed to neutralize the relatively increased amount of charge. Amount is required. In the case of a photoreceptor in which the carrier generation efficiency does not depend on the electric field, the relationship between the relative exposure amount and the surface potential becomes almost a straight line as shown in FIG. As a specific example, the charge transport layer CTL film thickness is 22 μm.
m, the dark area potential is -700 V, and the bright area potential is -150 V, the rate of change of the potential per unit film thickness (that is, per 1 μm) is as follows when a relative light amount of 1.0 is applied: (700-150) / 22 = 25V / μm. When using a scorotron to charge the dark area potential to -700 V at all times (that is, even when the film thickness is reduced),
In particular, in the vicinity of the light portion potential, the film thickness decreases and the 25V light portion potential per 1 μm increases, and the background fog is likely to occur. That is, the sensitivity changes due to the decrease in the thickness of the charge transport layer CTL. The carrier generation efficiency has an electric field dependence, but the dependence varies depending on the material of the CPC. When the electric field dependence increases, when the film thickness is small, the electric field under a constant charging potential condition increases, and the generation efficiency increases. This increase in sensitivity acts in a direction that compensates for the apparent decrease in sensitivity due to the decrease in film thickness described above. As a result, the light portion potential increases.

By the way, there are "filming" and "image deletion" as phenomena often seen in an image forming apparatus in which an OPC photosensitive member and a blade cleaner are combined. "Filming" is a phenomenon in which the components in the toner adhere to the surface of the OPC photoreceptor, grow gradually, the light does not attenuate, and a high potential is printed out. In particular, it is often seen in the magnetic one-component developing system, and is likely to occur when an original having the same pattern is repeatedly copied under high temperature and high humidity. Also, "image flow"
Is a phenomenon in which images are missing due to high-temperature and high-moisture hair. This is because paper powder such as talc, rosin, and starch contained in the transfer paper adheres to the surface of the photoreceptor during the transfer process, and is strongly rubbed against the photoreceptor by a cleaning blade, which absorbs water under high humidity. A large amount of discharge products (NO _x , O ₃ ) are constantly generated from the corona discharge device, and the water-soluble components in this discharge into the paper powder attached to the photoreceptor surface, dissociate the ions, This is caused by the fact that the electric resistance on the body surface is extremely reduced and the latent image leaks along the surface. As a countermeasure for these, on the cleaning blade side, the hardness of the urethane rubber constituting the blade is increased, or the pressure of the blade is increased, so that the surface of the photoreceptor is rubbed more strongly to remove deposits on the surface of the photoreceptor. It is effective to scrape off mechanically. However, if the cleaning blade alone is used to obtain the scraping effect, the charge transport layer CTL is inevitably used in a more aggressive manner, resulting in deterioration of the photoreceptor and the problems described above. . As a drastic solution to the various problems described above, a method using a toner deter bar brush that removes untransferred toner and paper powder from the photoconductor or disturbs the photoconductor to weaken the adhesion upstream of the cleaning blade, The applicant has already proposed (Japanese Utility Model Application No. 62-52088, Japanese Utility Model Application Laid-Open No. 63-160576). By properly selecting the parameters of the mechanical contact state of the deter bar brush to the photoreceptor, the pressing force and hardness of the cleaning blade can be minimized, and the charge transport layer by the dester bar brush itself. The wear of the CTL can be minimized.

Based on the above findings, the following were found as a result of examining the causes of wear of the CPC photoreceptor. In terms of the developing method, when the magnetic one-component toner is used and the two-component toner is used, the use of the magnetic one-component toner causes the photoreceptor to wear at about twice the speed. This is because the magnetic one-component toner usually contains 30 to 60% by weight of magnetic powder (iron powder). It is considered that when the toner is removed from the surface of the photoreceptor by the cleaning member, the photoreceptor is more easily scraped due to its high hardness. Regardless of whether the process speed (the peripheral speed of the photoconductor) is high or low, the wear of the photoconductor is almost the same.
The wear increases as the rotation time of the photoconductor increases, that is, as the number of copies increases. When the amount of toner supplied to the cleaning device is large or small (for example, when a large number of originals having many black portions are copied), the wear of the photoconductor is hardly related. When a blade attached so as to be in contact with the rotation direction of the photoconductor at an acute angle is used as the cleaning means, the photoconductor is worn in proportion to the pressure of the blade.
As described above by the applicant of the present invention (Japanese Utility Model Application No. Sho 62-52088 and Japanese Utility Model Application Laid-Open No. Sho 63-160576), the residual toner is agitated at the upstream of the cleaning blade to remove the residual toner from the photoreceptor and copy paper. Removes talc, paper dust, etc. from the surface, and always supplies a part of the toner as a lubricant to the downstream cleaning blade, and the friction between the cleaning blade and the photoconductor surface becomes too high because there is no lubricant. When a brush for toner deter bar (hereinafter referred to as an auxiliary brush) for preventing blade turning and chattering, which is a phenomenon in which the cleaning blade is caught in the direction of the photoconductor, the peripheral speed of the auxiliary brush and the peripheral speed of the photoconductor are used. connection of,
In addition, the amount (nip amount) of pushing the auxiliary brush against the photoconductor is the amount most relevant to the degree of wear of the photoconductor.

[Problems to be solved by the invention]

By the way, the shorter the OPC photoreceptor drum having an outer diameter of several centimeters to less than 10 centimeters, the longer the life of the drum (for example, 100,000 or more copies), The problem due to wear becomes a serious problem. In an apparatus capable of mass copying using the same CPC photoconductor, for example, when using a long photoconductor belt,
Since several latent images are placed on the entire circumference of the photoreceptor belt, the problem of the photoreceptor abrasion is not necessarily a major problem. However, as described above, a short-diameter OPC photosensitive drum usually has only one latent image or less on the outer periphery of the drum, so the speed is several times faster than that using an OPC photosensitive belt as described above. The image deteriorates, that is, only a few copies can be made.

Therefore, in particular, in an image forming apparatus using an OPC photosensitive drum having a short diameter, a cleaning means such as a cleaning blade arranged in close proximity to the photosensitive member is brought into contact with the photosensitive member at a position upstream thereof for the above-mentioned purpose. When using a cleaning device including an auxiliary brush that rotates in the moving direction, it is necessary to optimize the relationship between the peripheral speed of the auxiliary brush and the peripheral speed of the photoconductor, and the nip amount of the auxiliary brush with respect to the photoconductor. is there. However, conventionally, the life of an OPC photoconductor has been at the level of 50,000 to 80,000 sheets at the longest, so that these parameters have not been optimized from the viewpoint of such abrasion of the photoconductor.

Therefore, an object of the present invention is to provide a cleaning device for an image forming apparatus such as an electrophotographic copying machine, a printer, and a facsimile that uses an OPC photosensitive drum having a short diameter, and a cleaning unit and an auxiliary brush disposed upstream thereof. An object of the present invention is to provide conditions and means for minimizing abrasion of the photoreceptor by the auxiliary brush while maintaining the original operation of the auxiliary brush. The photoconductor is not necessarily limited to a short-diameter OPC photoconductor drum, and the cleaning unit is not necessarily limited to a cleaning blade.

[Means for solving the problem]

The present invention has been completed as a result of pursuing the cause of the abrasion of the photoreceptor as described above. In a cleaning device for an image forming apparatus for cleaning a toner, a cleaning unit arranged in close proximity to a latent image carrier and a roll-shaped member which is in contact with the latent image carrier at a position upstream thereof and rotates in the moving direction thereof A moving speed of the latent image carrier, including a toner
When the ratio of the peripheral speed of the brush for toner deter bar to x mm / sec is y, the peripheral speed ratio y is set so as to satisfy the condition of 60 / x + 1 ≦ y ≦ 1.8. Things.

In addition to this condition, the nip amount of the roll-shaped toner deter bar brush with respect to the latent image carrier is set to 0.4 mm or more and 1.2 mm or more.
When the thickness is set to be equal to or less than mm, the wear of the latent image carrier can be further reduced.

This cleaning device is most effective when applied to an image forming apparatus using an OPC photosensitive member as a latent image carrier and a cleaning blade as a cleaning means.

In order to further reduce the wear of the photosensitive member, the roll-shaped toner deter bar brush may be configured to be separated from the latent image carrier at a position other than the toner image area of the latent image carrier, or It is preferable that the speed be changed so as to be substantially the same as the movement speed of the body.

[Action]

In the present invention, the cleaning device is provided by a cleaning unit disposed in close proximity to the latent image carrier and a brush for a roll-shaped toner deter bar that is in contact with the latent image carrier at a position upstream thereof and rotates in the moving direction. By setting the peripheral speed ratio y of the toner deter bar brush to the moving speed x mm / sec of the latent image carrier to be 60 / x + 1 ≦ y ≦ 1.8, the latent image serving as the toner deter bar brush It removes residual toner, talc, paper dust, etc. from the copy paper from the carrier, and always supplies a portion of the recovered toner to the downstream cleaning blade as a lubricant. Wear can be minimized.

〔Example〕

Next, embodiments of the present invention will be described with reference to the accompanying drawings.

1 of an image forming apparatus using the cleaning device of the present invention
The overall configuration of the example consists of an OPC
Including a photoreceptor drum, a photoreceptor unit comprising a cleaning device and a charging device of the present invention, a developing unit, a transfer unit, a fixing unit, and a paper tray, each of which can be independently pulled out toward the front of the apparatus. Each unit can be removed from the apparatus for maintenance such as paper jams and cleaning. The photoreceptor unit is configured to be replaced with a new one every 100,000 copies, for example. During 100,000 copies, the residual toner collected from the photoconductor drum by the cleaning device of the present invention is automatically and reliably collected and stored in the photoconductor unit, and the user is recovered in the photoconductor unit. It does not come into contact with the residual toner.

FIG. 1 shows a cross section taken perpendicular to the rotation axis of the photoconductor drum of the photoconductor unit 1 having the cleaning device according to one embodiment of the present invention, and FIG. 2 shows a line II-II 'in FIG. The section taken is shown. In the drawing, cylindrical side plates 5 and 7 made of die-cast are fitted at both ends of the photosensitive drum 3, and a first space for storing residual toner is defined by a space partitioned by the photosensitive drum 3 and the side plates 5 and 7. The container 4 is constituted. A rotating shaft 9 is integrally provided at the center of the side plate 7 on the rear side of the photoconductor drum 3 and is rotatably attached to a housing 11 of the photoconductor unit 1 via a bearing. A circular opening is provided at the center of the side plate 5 on the front side, and is rotatably fitted via a bearing to a cylindrical portion 13 projecting from the housing 11 to the inside of the unit. A gear 15 is cut on the outer periphery of the rear side plate 7 so that when the unit 1 is pushed into the apparatus main body from the front and set, the gear 15 meshes with a drum rotation drive gear (not shown) on the apparatus main body side. ing. A positioning hole (not shown) into which the tip of the rotating shaft 9 protruding out of the housing 11 is fitted into the apparatus main body, and a housing of the unit 1.
Shaft (not shown) that fits into positioning hole 16 provided in 11
And constitute a positioning mechanism when the unit 1 is pushed into the apparatus main body and set.

A roll-shaped toner deter bar brush (hereinafter referred to as an auxiliary brush) 17 is rotatably mounted via a bearing between extended side walls of a housing 11 provided at both ends of the photosensitive drum 3, and is shown by an arrow in the figure. By rotating the auxiliary brush 17 in the same direction as the moving direction of the photosensitive drum 3 at the contact position with respect to the photosensitive drum 3,
The toner remaining on the drum 3 without being transferred by the transfer device, talc, paper dust and the like from the copy paper are removed and adhere to the surface of the photoreceptor, so that the flow of the copy image, comet, fog, etc. This prevents the image from deteriorating due to the occurrence of the toner, and prevents the filming that the toner adheres to the surface of the photoconductor and cannot be removed.
A part of the toner stagnated in 17 is always supplied to the cleaning blade 23 as a lubricant. The auxiliary brush 17 is formed by implanting resinous bristles such as polypropylene at a high density all around the rotary shaft 19 in a roll shape, and has a rear end (rear side of the device) of the rotary shaft 19. The gear 21 is fixed, and meshes with a gear 29 for rotationally driving the toner transport rotary paddle 27 described later. Further, an elastic cleaning blade 23 is provided downstream of the contact point between the photosensitive drum 3 and the auxiliary brush 17 so that one side is fixed to the housing 11 and the other side contacts the drum 3 at an acute angle with respect to the rotation direction. The auxiliary brush 17 scrapes off toner, talc, paper dust, and the like left from the photosensitive drum 3. Further, a scraping member 22 for scraping the toner adhered to the auxiliary brush 17 downward is formed by a partition wall described later.
The tip is in contact with the auxiliary brush 17. Further, in order to transport the residual toner scraped onto the bottom plate 25 of the housing 11 by the auxiliary brush 17 and the cleaning blade 23 in a direction away from the cleaning device 30, the rear side of the auxiliary brush 17 in the housing 11 (from the drum 3). On the far side), a toner conveying rotary paddle 27 is provided in parallel with the toner conveying rotary paddle 27 via a bearing.
A gear 29 is fixed to the rear end of the shaft of the rotary paddle 27 and meshes with the gear 21 for rotating the auxiliary brush 17, so that the rotary paddle 27 and the auxiliary brush 17 rotate in the direction of the arrow shown in the figure. By the way, the housing 11 forms a toner collection box 31, which is a second container for storing residual toner, on the rear side of the cleaning device 30 including the auxiliary brush 17, the cleaning blade 23, and the toner conveying rotary paddle 27. The cleaning device 30 and the toner collection box 31 are partially separated by a partition wall 32. An elastic plate-like member 34 is provided so that one end is fixed to the partition wall 32 and extends downward, and the lower end thereof is in elastic contact with the plane of the rotary paddle 27. The rotating paddle 27 has a regular polygonal cross section as shown in the figure, and has the function of scraping residual toner accumulated on the rear side of the auxiliary brush 17 into the toner collecting box 31 by rotating in the direction of the arrow shown in the figure. . The plate-like member 34, whose tip is in elastic contact with the surface of the polygonal cross section, has a function of scraping off the toner adhered to the surface and a function of returning the toner accumulated in the toner collection box 31 to the inside of the cleaning device 30 again. Has the effect of preventing.

A rotating shaft 33 is rotatably provided on the rear housing 11 near the bottom of the toner collection box 31. On the toner collection box 31 side, a strip-shaped plate-like member is formed with a normal to the surface. An elastic toner conveying auger 35 formed in a helical shape (spiral shape) so as to face the axial direction is coaxially fixed. Further, a gear 37 for auger rotation is attached to the rear end of the rotation shaft 33 via a torque limiter mechanism 38 which is disconnected when a predetermined torque or more is applied. The toner transport auger 35 extends in parallel with the toner transport rotary paddle 27 and the like along the bottom of the toner recovery box 31, and has a tip projecting through a circular opening 39 provided in a front wall of the housing 11. ing.
The circular opening 39 and the hole 41 inside the cylindrical portion 13 projecting from the housing 11 are connected by a pipe 43 having an inner diameter slightly larger than the cross section of the toner conveying auger 35, and projecting through the circular opening 39. Auger for conveying toner
35 is bent along the pipe 43, and its tip 45 projects into the space 4 inside the drum 3. As described above, the toner conveying auger 35 has a shape of a flexible helical spring, and when it is rotated, the toner conveying auger 35 acts to convey the toner that has entered between the blades in the axial direction by the principle of a helical pump. Is what you do. Therefore, by rotating the toner collection box 31 in the toner collection box 31, the residual toner at the bottom in the toner collection box 31 is removed along the pipe 43 into the space 4 in the drum 3.
Can be transported to The toner transport auger 35
Both the rotating gear 37 and the rotating paddle 27 are engaged with a driving gear 47 rotatably provided on a rear wall of the housing 11, and the driving gear 47 is When the photoreceptor unit 1 is set in the apparatus main body, the photoreceptor unit 1 is engaged with a driving gear (not shown) provided in the main body, and the cleaning brush 17, the toner conveying rotary paddle 27, the toner conveying auger
Rotate 35. The toner transport auger 35 may be, for example, a flexible wire having a helical plate-shaped protrusion around the toner in addition to the helical spring-shaped one as described above.

In the toner collection box 31, a float member 49 is provided that floats from below by the accumulated toner when the residual toner contained in the toner collection box 31 has reached a predetermined amount or more. An opaque shielding member 51 is provided integrally. Further, a projection 53 made of a transparent wall is provided on the upper part of the housing 11 and forms a space into which the shielding member 51 enters from below when the float member 49 floats and rises. On the other hand,
A groove 55 into which the projecting portion 53 enters when the photoconductor unit 1 is set is provided, and a light emitting element 57 and a light receiving element 59 are provided on both sides of the groove 55 so as to face each other. Therefore, when the amount of residual toner in the toner collection box 31 exceeds a predetermined amount, the float member 49 rises so as to follow its surface, and the shielding member 51 also rises. This shielding member 51 is
When it rises inside and reaches a certain height, an optical path that exits the light emitting element 57 and penetrates the protruding portion 53 and reaches the light receiving element 59 is blocked. Therefore, by detecting this interruption, it is possible to detect that the toner collection box 31 is full with the collected residual toner. For details of the fullness detection mechanism 60, refer to Japanese Utility Model Application Laid-Open No. 63-39259, which was previously filed by the present applicant as Japanese Utility Model Application No. 61-132700. It should be apparent that the fullness detection mechanism 60 is not limited to the above-described one, and various known types can be used.

In FIG. 1, the photoreceptor unit 1 is integrally provided with a charger 61 for uniformly charging the cleaned photoreceptor drum for forming a latent image downstream of the cleaning blade 23. .

The operation of the photoreceptor unit having the cleaning device having the above-described configuration according to the embodiment of the present invention will be described.

The photosensitive drum 3 uniformly charged by the charger 61
The image exposure is performed in an exposure unit (not shown), and an electrostatic latent image is formed on the surface of the photosensitive drum 3. Next, in a developing device (not shown), the toner charged to the opposite polarity to the charge of the electrostatic latent image is brought into contact with the surface of the photosensitive drum 3 to form a toner image. The toner image contacts a sheet conveyed at the same speed as the peripheral speed of the photosensitive drum 3 and is transferred onto the sheet in a transfer device (not shown) provided at the next position. The sheet on which the toner image has been transferred is conveyed to a fixing device, where the toner image is fixed on the sheet and discharged from the apparatus.

On the other hand, the photosensitive drum 3 reaches the cleaning device 30,
The toner remaining on the surface without being transferred by the transfer device is removed by a rotating roll-shaped auxiliary brush 17 as if scraped up from below. Part of the removed toner adheres to the auxiliary brush 17 and is scraped off by the scraping member 22.
And when the auxiliary brush 17 collides with the scraping member 22, the auxiliary brush 17 is flipped off and scraped onto the bottom plate 25 of the housing 11. In addition, a part of the toner removed by the auxiliary brush 17 and a part of the toner remaining in the auxiliary brush 17 are scattered toward the cleaning blade 23 and are always supplied as a lubricant for the cleaning blade 23.
The auxiliary brush 17 removes not only residual toner but also talc, paper dust, and the like, which are generated from copy paper and adhere to the surface of the photoreceptor drum 3 and cause deterioration of a copied image such as image flow, comet, and fog. Works. The toner remaining on the photosensitive drum 3 without being scraped off by the auxiliary brush 17 is scraped off by the cleaning blade 23 and similarly falls onto the bottom plate 25 of the housing 11. The cleaning blade 23 is made of an elastic material such as polyurethane rubber, and is arranged at an acute angle with respect to the rotation direction of the photosensitive drum 3 so as to be in contact with the surface thereof, as shown in FIG. When there is no photosensitive drum 3, friction with the photosensitive drum 3 causes the photosensitive drum 3 to be caught in the peripheral speed direction (in the direction of the arrow in the drawing), causing the blade to be turned up, causing chattering and no longer functioning as a cleaning unit. . Therefore, the configuration in which a part of the toner removed from the auxiliary brush 17 is always supplied to the cleaning blade 23 as a lubricant as described above is important especially in a cleaning device employing blade-shaped cleaning means. It is. It is conceivable that the rotation direction of the auxiliary brush 17 is opposite to that shown in the drawing, and the auxiliary brush 17 is moved in the opposite direction at the point of contact with the photosensitive drum 3. However, if such a direction is selected, As described above, it becomes impossible to supply a part of the toner as a lubricant to the cleaning blade 23, the contact with the photoconductor becomes strong, and the photoconductor is easily damaged. In this embodiment, the auxiliary brush 17 is moved in such a direction because there is a problem that the toner is easily overflown due to an increase in the amount of toner accumulated in the toner, and it is difficult to find an appropriate arrangement position of the scraping member 22. Is not rotated.

Residual toner written off by the auxiliary brush 17 and the cleaning blade 23 and accumulated on the bottom plate 25 of the housing 11 is transferred to the toner transport rotary paddle 27 rotating at this position.
Accordingly, the toner is scraped into a toner collection box 31 provided adjacent to the cleaning device 30. Residual toner scraped into the toner collection box 31 is desirably removed from the toner conveyance rotation paddle 27 near the bottom of the toner collection box 31.
Is transported to the space 4 in the photosensitive drum 3 via the pipe 43 by the rotation of the toner transport auger 35 provided near the photosensitive drum 3. The toner transport auger 35 can rotate around the shaft and transport the residual toner in the axial direction while being bent by the elasticity even in the pipe 43. During this time,
The residual toner scraped into the toner collection box 31 is
Since the toner is transferred to the space 4 in the photosensitive drum 3 sequentially by the toner transfer auger 35, the residual toner does not accumulate in the toner collection box 31. When the space 4 in the photosensitive drum 3 is filled with the residual toner, a large resistance starts to be applied to the toner conveying auger 35. When the resistance becomes equal to or larger than a predetermined value, a torque limiter mechanism 38 provided between the rotation shaft 33 of the toner transport auger 35 and the auger rotation gear 37 acts, and the toner transport auger 35 rotates. The conveyance of the residual toner to the space 4 in the photosensitive drum 3 stops. Therefore, the residual toner scraped out by the toner transport rotation paddle 27 starts to accumulate in the toner collection box 31. When the amount of the residual toner contained therein exceeds a predetermined amount, the float member 49 rises so as to follow its surface, and the shielding member 51 also rises. When the shielding member 51 rises inside the protruding portion 53 and reaches a certain height, the light path that exits the light emitting element 57 and penetrates the protruding portion 53 to reach the light receiving element 59 is cut off, whereby the toner It is possible to detect that the collection box 31 is filled with the collected residual toner. This signal may be used to stop the copying apparatus. However, at a position where the shielding member 51 first blocks the optical path from the light emitting element 57 to the light receiving element 59, the residual toner is further stored in the toner collection box 31 by a predetermined amount. This signal is used as a warning signal that warns that the space 4 in the photosensitive drum 3 and the toner collection box 31 will be full with the collected residual toner after a predetermined number of copies. It can also be used. The photoconductor unit 1 thus filled with the residual toner is replaced with a new one.

By the way, as mentioned before, using an OPC photoconductor,
When the cleaning device 30 having the above-described configuration is employed, the degree of wear of the charge transport layer CTL of the photoconductor depends on the relationship between the peripheral speed of the auxiliary brush 17 and the peripheral speed of the photoconductor drum 3, and It has been found that it largely depends on the nip amount with respect to the photosensitive drum 3. This point will be described. First, the third
The figure shows the result of examining the amount of wear of the charge transport layer CTL after copying 100,000 sheets using the pressure of the cleaning blade 23 on the photoconductor 3 as a variable. In this figure, the diameter of the photoreceptor drum 3 is 84 mm (having an outer periphery of a vertical length of approximately A4 size).
And the peripheral speed of the photosensitive drum 3 is x mm / sec.
When the peripheral speed of 17 is z mm / sec, the ratio z / x is defined as the peripheral speed ratio y of the auxiliary brush 17, and this value y is 1.2,
The nip amount of the photosensitive drum 3 of No. 7 is defined as the pushing amount of the auxiliary brush 17 against the surface of the photosensitive drum 3 as shown in FIG. 4, and is a graph when the nip amount is 1.0 mm. The auxiliary brush 17 has an outer diameter of 19 mm and a shaft diameter of 6 mm.
The material of the hair is polypropylene resin, 17 denier, density is 60,000 / in ² , pile height is 5.5m
What was m was used. Also, cleaning blade 23
Made of thermosetting polyurethane, hardness 70 ゜ H
s, a width of 10 mm, a thickness of 2 mm, and a contact angle θ of 22 ° shown in FIG. 1 were used. As is apparent from FIG. 3, the charge transport layer CTL is worn in proportion to the pressure of the cleaning blade 23. However, if this pressure is less than 1.0 gf / mm, cleaning failure will occur.
23 pressure cannot be less than this.

Next, FIG. 5 shows the result of examining the amount of wear of the charge transport layer CTL after copying 100,000 sheets using the peripheral speed ratio y of the auxiliary brush 17 as a variable. The conditions are almost the same as in the case of FIG. 3, but in this case, the pressure of the cleaning blade 23 on the photoreceptor 3 is 1.2 gf / mm. From FIG. 5, it can be seen that when the peripheral speed ratio y of the auxiliary brush 17 is 1.0, the amount of wear of the charge transport layer CTL is minimum, and the amount of wear increases even if it is larger or smaller.
It can be seen that when the value exceeds 1.8, the amount of wear of the charge transport layer CTL increases rapidly. Considering the amount of wear caused by the pressure of the cleaning blade 23 in FIG.
It can be seen how rapidly the increase in the amount of abrasion due to is caused.
When the peripheral speed ratio y is 1.0, the peripheral speed x of the photosensitive drum 3 and the peripheral speed z of the auxiliary brush 17 are equal. Since the auxiliary brush 17 rubs the surface of the photoreceptor drum 3, it is considered that the amount of abrasion increases, which is a satisfactory result. From the above, the peripheral speed ratio y needs to satisfy the following condition: y ≦ 1.8.

By the way, as described above, the role of the auxiliary brush 17 is not only to scrape off the residual toner on the photosensitive drum 3 but also to prevent the talc of the copy paper from adhering to the surface of the photosensitive drum 3 to prevent the deterioration of the copied image. It is to be. Auxiliary brush
FIG. 6 shows the result of examining the talc adhesion amount using the peripheral speed ratio y of 17 as a variable and the process speed (the peripheral speed x of the photosensitive drum 3) as a parameter. In this graph, the amount of photoreceptor talc adhering after 1000 sheets of acidic paper (containing talc) was printed as a blank copy was evaluated in five grades, and the other conditions were the same as those in FIG. From this figure, y = 1 at which the peripheral speeds of the photosensitive drum 3 and the auxiliary brush 17 become equal.
In this case, the scraping force of the brush 3 becomes the weakest, and when the process speed is changed, if the peripheral speed ratio y is changed uniformly, a good result is not always obtained, and the process speed x and the peripheral speed z of the auxiliary brush 17 are not always obtained. It is understood that it is necessary to take a difference of 60 mm / sec or more. Specifically, the process speed x is 100 m
At m / sec, unless the peripheral speed ratio y is 1.6 or more, talc rapidly adheres to the surface of the photosensitive drum 3. Process speed x is 20
At 0 mm / sec, the peripheral speed ratio y must be 1.3 or more.
Similarly, when x is 300 mm / sec, y is 1.2 or more and x is 400 mm / sec.
In sec, y must be greater than or equal to 1.15. This is x
Is plotted on the horizontal axis and y on the vertical axis, the circles are as shown in FIG. 7, and when these circles are connected, a curve of y = 60 / x + 1 is obtained, and talc adheres to the surface of the photosensitive drum 3. It can be said that the condition y ≧ 60 / x + 1... Must be satisfied so that the copied image does not deteriorate. Seventh
The figure shows the region that satisfies both of the above conditions.
This is the area indicated by hatching.

The degree of wear of the charge transport layer CTL of the photoreceptor largely depends on the nip amount of the auxiliary brush 17 with respect to the photoreceptor drum 3 as described above. FIG. 8 shows the amount of wear of the charge transport layer CTL after copying 100,000 sheets.
FIG. 9 is a diagram showing a result of an investigation using a nip amount as a variable with respect to FIG. In this case, the peripheral speed ratio y of the auxiliary brush 17 is 1,2. From this figure, it can be seen that when the nip amount exceeds 1.2 mm, the abrasion amount of the CTL sharply increases (this is well understood by subtracting the abrasion amount due to the cleaning blade 23 in FIG. 3). As is clear from the figure, preferably 1.0 mm
The following nip amount is good. However, the nip amount is 0.4m
If it is smaller than m, the amount of talc adhering to the surface of the photoconductor drum 3 increases, and filming development in which toner adheres to the surface of the photoconductor drum occurs.

The amount of CTL wear varies depending on the thickness, material, and the like of the bristle used for the auxiliary brush 17, but the tendency shown in FIGS. 5 to 8 is the same.

As described above, by setting the condition of the peripheral speed ratio y of the auxiliary brush 17 and selecting the nip amount of the auxiliary brush 17, the wear of the OPC photoconductor can be reduced as much as possible. Or in addition to these, the photosensitive drum 3
At a time or position where a toner image is not formed on the surface, the auxiliary brush 17 is separated from the photosensitive drum 3 or
Alternatively, the wear amount of the photoreceptor can be further reduced by shifting the rotational peripheral speed to a speed at which wear is minimized. That is, as shown in the timing chart of FIG. 9, when the main charging, image exposure, development, and transfer times (lengths) are all equal and correspond to the length of the copy paper, the auxiliary brush 17 The drum 3 is brought into contact. If the auxiliary brush 17 does not come into contact with the photoconductor, the amount of wear of the charge transport layer CTL of the photoconductor is minimized, as is clear from FIGS. Therefore, the auxiliary brush 17 may be moved toward and away from the photosensitive drum 3 in accordance with the timing shown in FIG. For this purpose, for example, a configuration as shown in FIGS. 10 and 11 may be employed. That is, in the case of FIG. 2, the gear 21 fixed to the rear end of the shaft of the rotary paddle 27 is directly meshed with the gear 21 for rotating the auxiliary brush 17, and
The rotation shaft 19 of the auxiliary brush 17 was not swingable with respect to the housing 11. On the other hand, in the case of FIGS. 10 and 11, the rotating shaft 19 has one end attached to the plunger 75 of the solenoid 74 and is rotatable about the other end of the link 73 that can swing around the shaft 77. Installed. The gear 21 is not directly meshed with the gear 29, and the idler gears 71 and 72 are disposed so as to rotate about a shaft 77 on which the link 73 is swingably mounted. A return spring 76 is attached to one end of the link 73, and when the bias of the solenoid 74 is cut off, the link 73 is pivoted counterclockwise in FIG. With such a configuration, when the solenoid 74 is energized only at the timing of performing the cleaning shown in FIG.
10, the link 73 rotates clockwise, and the auxiliary brush 17 around the rotating shaft 19 attached to the other end comes into contact with the photosensitive drum 3. The nip amount of the auxiliary brush 17 with respect to the photosensitive drum 3 is determined by tracking rolls 78 and 78 'attached to both sides of the rotating shaft 19. Even if the rotating shaft 19 swings in this way, the swing center of the link 73 is
Since the rotation centers of the gears coincide with each other, the engagement of the gears from the gear 29 to the gear 21 is not disengaged, so that the rotational force from the driving gear 47 is continuously transmitted to the auxiliary brush 17. Solenoid 74
Is released, the link 73 swings counterclockwise by the force of the return spring 76, and the auxiliary brush 17 separates from the photosensitive drum 3. As shown in FIG. 11, a link 73 'similar to the link 73 is provided between the rotation shaft 19 and the shaft 77 on the side opposite to the gear train (on the front side of the apparatus). The separation and contact with the drum 3 are ensured. If the auxiliary brush 17 is left on the photosensitive drum 3, a part of the bristles of the brush will be curled, and the set part will cause vibration of the rotating auxiliary brush 17. Although this is transmitted to the photosensitive drum 3 and contributes to deterioration of the image quality, this problem can be solved by adopting the separation structure as described above.

As is apparent from FIG. 5, when the peripheral speed ratio y of the auxiliary brush 17 is 1.0, the amount of wear of the charge transport layer CTL is minimal, and the amount of wear is small.
In this case, the rotation speed of the auxiliary brush 17 is set to 2 according to the timing shown in FIG. 9 instead of moving the auxiliary brush 17 to and away from the photosensitive drum 3 as described above.
You may make it change into a step. That is, in the toner image area, the auxiliary brush 17 is rotated at any speed in the shaded area in FIG. 7, and in other cases, the auxiliary brush 17 is rotated so as to have a peripheral speed substantially equal to the peripheral speed of the photosensitive drum 3. Change the rotation speed. For this purpose, any known transmission mechanism may be used. For example, two gears with different numbers of teeth are coaxially fixed to the rotating shaft 19, while two gears with different numbers of teeth are rotatably mounted on a drive shaft arranged in parallel with the rotating shaft 19, and each is fixed. The gear of the shaft 19 is engaged. Then, any gear coaxial with the drive shaft may be selectively fixed to the drive shaft using an electromagnetic clutch.

In the above description, the photoconductor has been described as a photoconductor drum having a short diameter of the OPC.
The present invention is not limited to the OPC photoconductor drum, but may be applied to, for example, a belt-shaped photoconductor. Further, it was assumed that a cleaning blade was used as the cleaning means, but this point is not limited to this. For example, a cleaning brush or a wiper blade having an installation angle opposite to that of the cleaning blade of the present embodiment is used. It is also possible to use a cleaner or the like.

〔The invention's effect〕

In the present invention, the cleaning device is provided by a cleaning unit disposed in close proximity to the latent image carrier and a brush for a roll-shaped toner deter bar that is in contact with the latent image carrier at a position upstream thereof and rotates in the moving direction. By setting the peripheral speed ratio y of the toner deter bar brush to the moving speed x mm / sec of the latent image carrier to be 60 / x + 1 ≦ y ≦ 1.8, the latent image serving as the toner deter bar brush It removes residual toner, talc, paper dust, etc. from the copy paper from the carrier, and always supplies a portion of the recovered toner to the downstream cleaning blade as a lubricant. Wear can be minimized.

In addition, by setting the nip amount of the roll-shaped toner deter bar brush to the latent image carrier at 0.4 mm or more and 1.2 mm or less, the wear of the latent image carrier can be further reduced.

This cleaning device is most effective when applied to an image forming apparatus using an OPC photosensitive member as a latent image carrier and a cleaning blade as a cleaning means.

In order to further reduce the wear of the photosensitive member, the roll-shaped toner deter bar brush may be configured to be separated from the latent image carrier at a position other than the toner image area of the latent image carrier, or It is preferable that the speed be changed so as to be substantially the same as the movement speed of the body.

[Brief description of the drawings]

FIG. 1 is a sectional view taken along a line perpendicular to the rotation axis of a photosensitive drum of a photosensitive unit having a cleaning device according to a first embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II 'of FIG. FIG. 3 is a cross-sectional view, and FIG. 3 is a view showing the result of taking the amount of wear of the charge transport layer CTL by using the pressure of the cleaning blade on the photoconductor as a variable. FIG. 4 is a diagram for explaining the nip amount of the auxiliary brush with respect to the photoconductor drum. Figure 5 shows the charge transport layer CTL
FIG. 6 is a diagram showing a result obtained by taking the amount of wear of the auxiliary brush as a variable with the peripheral speed ratio y of the auxiliary brush, and FIG. FIG. 7 is a diagram showing the range of the peripheral speed ratio y of the auxiliary brush permitted by the present invention with the process speed x as a variable. FIG. 8 is a graph showing the wear amount of the charge transport layer CTL on the nip of the auxiliary brush with respect to the photosensitive drum. FIG. 9 is a diagram showing the result of an examination using the amount as a variable, FIG. 9 is a timing chart when the cleaning device of another embodiment of the present invention is applied to the image forming apparatus using the photoreceptor unit of FIG. 1, and FIG. FIG. 11 is a side view showing a main part of a configuration in a case where the auxiliary brush is moved toward and away from the photosensitive drum according to the present invention.
12 is a cross-sectional view of the OPC photoreceptor, and FIG. 13 is a view showing the relationship between the relative exposure and the surface potential when the thickness of the four charge transport layers CTL is used as a parameter. is there. 1 photoconductor unit, 3 photoconductor drum, 4 space in photoconductor drum, 5, 7 cylindrical side plate, 9 rotating shaft, 11 housing, 13 inside housing from housing Protruding cylindrical portion, 15 ... gear cut on the outer periphery of side plate, 16 ... positioning hole, 17 ... brush for toner deter bar, 19 ... rotating shaft of brush for toner deter bar, 21 ... toner Gears fixed to the rotation shaft of the brush for the deter bar, 22: scraping member, 23: cleaning blade, 25: bottom plate of housing, 27: toner transport rotary paddle, 29: toner transport rotary paddle rotary drive , A cleaning device, 31 a toner collecting box, 32 a partition wall between the cleaning device and the toner collecting box, 33 a rotating shaft, 34 a plate member, 35 a toner conveying auger, 37 ...... Auger Diversion of gear, 38 ......
Torque limiter mechanism, 39: circular opening provided in front wall of housing, 41: hole, 43: pipe, 45:
Auger tip, 47 ... a driving gear rotatably provided on the rear wall of the housing, 49 ... a float member,
51 ... Shielding member, 53 ... Projection made of transparent wall, 55 ...
Groove into which projecting part enters, 57: Light emitting element, 59: Light receiving element, 60: Full detection mechanism, 61: Charger, 71, 72 ... Idler gear, 73 ... Link, 74 ... Solenoid, 75 …
… Plunger, 76 …… return spring, 77 …… axis, 78, 78 '
…… Tracking roll

Continued on the front page (72) Inventor Mikio Kobayashi 2274 Hongo, Ebina-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd. Ebina Works (56) References JP-A-60-168183 (JP, A) JP-A-60-168182 (JP) JP-A-61-36969 (JP, A) JP-A-1-170976 (JP, A) JP-A-63-221376 (JP, A) JP-A-63-88572 (JP, A) 59-19984 (JP, A) Japanese Utility Model 63-178868 (JP, U) Japanese Utility Model 2-10561 (JP, U) Japanese Utility Model 63-160576 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) G03G 21/00-21/12

Claims (6)

(57) [Claims] 1. A cleaning device for an image forming apparatus for cleaning residual toner on a moving latent image carrier, comprising:
Cleaning means arranged in proximity to the latent image carrier,
A roller-shaped toner deter bar brush that rotates in the moving direction in contact with the latent image carrier at a position upstream thereof, and a peripheral speed of the toner deter bar brush with respect to the moving speed x mm / sec of the latent image carrier. Wherein the peripheral speed ratio y is set so as to satisfy the following condition: 60 / x + 1 ≦ y ≦ 1.8. 2. The cleaning device for an image forming apparatus according to claim 1, wherein the nip amount of the brush for the roll-shaped toner deter bar with respect to the latent image carrier is set to 0.4 mm or more and 1.2 mm or less. 3. The cleaning device according to claim 1, wherein an OPC photosensitive member is used as the latent image carrier. 4. The cleaning device for an image forming apparatus according to claim 1, wherein a cleaning blade is used as the cleaning means. 5. The toner brush according to claim 1, wherein the brush for the toner debar bar is separated from the latent image carrier at a position other than the toner image area of the latent image carrier. 2. The cleaning device for an image forming apparatus according to claim 1. 6. The apparatus according to claim 1, wherein the peripheral speed of the roll-shaped toner deter bar brush is changed to be substantially the same as the moving speed of the latent image carrier at a position other than the toner image area of the latent image carrier. The cleaning device for an image forming apparatus according to claim 1, wherein: