JP2010060679A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device preventing image deletion without generating image disorder due to jitter without need to add a member in particular. <P>SOLUTION: This image forming device includes a photoreceptor, an intermediate transfer body which is oppositely arranged to the photoreceptor and onto which a toner image formed on the surface of the photoreceptor is transferred, a sliding roller which makes cleaning by carrying toner on the surface and grinding the surface of the photoreceptor, and a friction resistance value detection means which detects a friction resistance value of the surface of the photoreceptor. The friction resistance value detection means detects the friction resistance value based on the density of a density detection toner image formed on the surface of the photoreceptor and the surface of the intermediate transfer body. When the frictional resistance value detection means detects a value larger than a predetermined friction resistance value, the rotation speed ratio of the sliding roller in relation to the photoreceptor is changed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus, and more particularly to an image forming apparatus that forms a color image using an intermediate transfer system as a transfer system.

In conventional electrophotographic image forming apparatuses such as copying machines, fax machines, and printers, image quality degradation due to image flow has been a problem.
Image flow is a phenomenon in which an image is blurred or rubbed, and the discharge product (active substances such as ozone and nitrogen oxides generated during corona discharge and their reaction products) is water-soluble on the surface of the photoreceptor. This occurs because a conductive foreign matter such as a body adheres and latent image charges flow in the direction of the latent image surface.

  As a means for solving this problem, a photoconductive member after an image is transferred to a sheet of toner having abrasive properties with an abrasive attached to a cleaning roller (rubbing roller) provided between a transfer device and a cleaning blade. A technology that reduces the surface roughness of the photoconductor and removes foreign matter such as water discharges from discharge products on the surface of the photoconductor by carrying the toner remaining on the surface and thereby polishing the surface of the photoconductor It has been known.

  However, when the adhesion of foreign matter to the photoconductor increases due to the operating environment of the image forming apparatus, the transfer paper used, the state of the toner, etc., or when the abrasiveness decreases due to a decrease in toner external additives, etc. Since the adhesion of foreign matter exceeds the polishing action of the rubbing roller, the surface condition of the photoconductor deteriorates and the surface friction coefficient increases, causing an increase in drive torque of the photoconductor, stick slip of the cleaning blade, and the like. Therefore, there is a possibility that problems such as generation of blade vibration noise, winding of the blade, color misregistration, and poor cleaning may occur.

  Therefore, Patent Document 1 discloses an image forming apparatus in which a rubbing roller rotates in the same direction as the rotation direction of the photosensitive member and at a peripheral speed of 120% with respect to the photosensitive member at all times during the image forming operation. As a result, a high polishing power can be obtained, so that the surface friction coefficient of the photoreceptor is not increased, and problems such as defective cleaning do not occur.

  Patent Document 2 discloses an image forming apparatus that includes a plurality of rubbing rollers and is set so that the rotation directions of adjacent rubbing rollers are different from each other. According to this, a high polishing force is obtained, the surface friction coefficient of the photoreceptor is not increased, and problems such as defective cleaning are not generated. Further, it is not easily affected by the rubbing load between the rubbing roller and the photosensitive drum and its fluctuation.

However, as in Patent Document 1, during the image forming operation, if the rubbing roller is rotated in the same direction as the photosensitive drum and at a higher rotation speed than the rotation of the photosensitive drum, the polishing force of the photosensitive member is reduced. Although it can be improved sufficiently, there is a problem that jitter due to rotational unevenness and rotational position deviation is likely to occur due to the frictional load of the rubbing roller and the photosensitive drum and the fluctuation thereof, and appear as image disturbance. is there.
The image forming apparatus of Patent Document 2 uses a plurality of rubbing rollers, and thus has a large number of members and a complicated structure, resulting in a problem that the apparatus itself becomes large or costs increase.

JP 7-234619 A JP 2004-361775 A

  In view of the above problems, the problem to be solved by the present invention is to provide an image forming apparatus that can prevent image flow without causing image distortion due to jitter without the need for additional members. is there.

  According to the first aspect of the present invention, there is provided a photoreceptor, an intermediate transfer member that is disposed opposite to the photoreceptor and onto which a toner image formed on the surface of the photoreceptor is transferred, and a surface of the photoreceptor that carries toner on the surface. An image forming apparatus having a rubbing roller for cleaning by polishing and a frictional resistance value detecting means for detecting a frictional resistance value of the surface of the photoreceptor, wherein the frictional resistance value detecting means is the surface of the photoreceptor or The frictional resistance value is detected based on the density of the density detection toner image formed on the surface of the intermediate transfer body, and when the frictional resistance value detecting means detects a value larger than a predetermined frictional resistance value. A rotation ratio of the rubbing roller to the photosensitive member is changed.

  According to a second aspect of the present invention, the rubbing roller rotates in a direction opposite to the photosensitive member in a direction slower than the rotational speed of the photosensitive member, and a value larger than a predetermined frictional resistance value is detected by the frictional resistance value detecting means. The image forming apparatus according to claim 1, wherein when detected, the image forming apparatus rotates in a direction opposite to the photoconductor faster than a rotation speed of the photoconductor.

  According to a third aspect of the present invention, the rubbing roller rotates in a direction opposite to the photosensitive member in a direction slower than the rotational speed of the photosensitive member, and a value larger than a predetermined frictional resistance value is detected by the frictional resistance value detecting means. The image forming apparatus according to claim 1, wherein when detected, the image forming apparatus rotates in the same direction as the photoconductor.

  According to a fourth aspect of the invention, the frictional resistance value detecting means is a density detection sensor for detecting the density of a density detection toner image formed on the surface of the intermediate transfer member. The image forming apparatus according to any one of the above.

  According to a fifth aspect of the invention, there is provided the image forming apparatus according to any one of the first to fourth aspects, wherein the detection by the frictional resistance value detecting means is performed during non-image formation.

  The invention according to claim 6 relates to the image forming apparatus according to claim 5, wherein the non-image forming time is when the apparatus power is turned on.

  The invention according to a seventh aspect relates to the image forming apparatus according to the fifth or sixth aspect, wherein the non-image formation is after a predetermined number of image forming processes have been performed.

According to the first aspect of the present invention, the photosensitive member, the intermediate transfer member that is disposed opposite to the photosensitive member and onto which the toner image formed on the surface of the photosensitive member is transferred, and the surface of the photosensitive member that carries the toner on the surface are mounted. An image forming apparatus having a rubbing roller for cleaning by polishing and a frictional resistance value detecting means for detecting a frictional resistance value on the surface of the photoreceptor, wherein the frictional resistance value detecting means is the surface of the photoreceptor or the intermediate transfer body By detecting the frictional resistance value based on the density of the density detection toner image formed on the surface, it is possible to detect the frictional resistance value on the surface of the photoreceptor without any additional member.
Further, when a value greater than the predetermined friction resistance value is detected by the friction resistance value detecting means, the rotation ratio of the rubbing roller to the photosensitive member is changed, so that the polishing power is increased only when necessary, so that jitter occurs. It is difficult to prevent image distortion.

  According to the second aspect of the present invention, the rubbing roller rotates in the direction opposite to the photosensitive member in the direction opposite to the rotational speed of the photosensitive member, and a value larger than the predetermined frictional resistance value is detected by the frictional resistance value detecting means. Occasionally, it rotates faster than the rotation speed of the photoconductor in the opposite direction to the photoconductor, so that it is not easily affected by the rubbing load and its fluctuation, and does not generate jitter due to rotation unevenness or rotational position shift, thereby improving the polishing performance. Can do.

  According to the invention of claim 3, the rubbing roller rotates in the direction opposite to the photosensitive member in the direction opposite to the rotational speed of the photosensitive member, and a value larger than the predetermined frictional resistance value is detected by the frictional resistance value detecting means. In this case, higher polishing performance can be easily obtained by rotating in the same direction as the photoconductor.

  According to the fourth aspect of the present invention, since the frictional resistance value detecting means is a density detecting sensor for detecting the density of the density detecting toner image formed on the surface of the intermediate transfer member, there is one density detecting sensor. Therefore, the number of members can be reduced, and the apparatus can be made compact and space-saving.

  According to the fifth aspect of the present invention, the detection by the frictional resistance value detecting means is performed at the time of non-image formation, so that jitter is generated even if it is affected by the frictional load fluctuation between the friction roller and the photosensitive member. I won't let you.

  According to the sixth aspect of the invention, since the non-image forming time is when the apparatus power is turned on, the frictional resistance value on the surface of the photosensitive member can be detected before the image forming operation, thereby preventing image disturbance. be able to.

  According to the seventh aspect of the present invention, since the non-image formation is after the predetermined number of image forming processes, the frictional resistance value of the surface of the photoconductor can be periodically detected, so that the friction of the surface of the photoconductor The resistance value can be maintained properly.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a preferred embodiment of an image forming apparatus according to the invention will be described with reference to the drawings.
FIG. 1 is a schematic view showing an image forming unit of an image forming apparatus according to the present invention.
As shown in FIG. 1, the image forming apparatus according to the present invention has an endless transfer belt (1) as an intermediate transfer member, and the transfer belt (1) extends over a driving roller (2), a driven roller (3), and the like. It is wound and rotated in the direction of the arrow in the figure.

Above the transfer belt (1), a plurality of image forming units (4) for developing with different color toners, more specifically, for magenta toner from the upstream side to the downstream side in the rotation direction of the transfer belt (1). An image forming unit (4M), a cyan toner image forming unit (4C), a yellow toner image forming unit (4Y), and a black toner image forming unit (4B) are arranged in this order.
Each of the image forming units (4M), (4C), (4Y), and (4B) has a photosensitive drum (5) that is rotationally driven, and a charging device is provided around the photosensitive drum (5). (6) An exposure device (7), a developing device (8), a cleaning blade (9), a static eliminator (not shown), and a rubbing roller (10) are provided.
The photoconductor drum (5) is an amorphous silicon photoconductor, but is not limited to this and may be an organic photoconductor.
The material of the rubbing roller (10) is not particularly limited, and examples thereof include foams of ethylene propylene diene terpolymer (EPDM).

A primary transfer roller (11) is provided so as to face each photosensitive drum (5) with the transfer belt (1) interposed therebetween.
A secondary transfer roller (not shown) is provided so as to face the driving roller (2) with the transfer belt (1) interposed therebetween. A cleaning blade (12) is provided on the front side of the transfer roller (1) in the traveling direction of the drive roller (2), and a density detection toner image (referred to as a patch) formed on the transfer belt (1) on the rear side in the traveling direction. Is provided with a density sensor (13). In the present embodiment, the density sensor (13) is also used as a frictional resistance value detecting means.
The primary transfer roller (11) and the secondary transfer roller (not shown) are provided with a power source for applying a bias voltage having a polarity opposite to the normal charging polarity of the toner, but are omitted in FIG. .

The image forming operation by this image forming apparatus is not particularly different from that of the conventional image forming apparatus, and in each image forming unit (4), the photosensitive drum (5) is rotated and driven by the charging device (6). A toner image is formed on the surface of the photoreceptor (5) by being exposed by the exposure device (7) and developed by the developing device (8).
Thereafter, by applying the bias voltage to the primary transfer roller (11), the toner image is transferred to the transfer belt (1) (primary transfer).
This operation is sequentially performed in the image forming units (4M), (4C), (4Y), and (4B) of the respective color toners while driving the transfer belt (1), and different colors are formed on the transfer belt (1). The toner is superposed to form a full color toner image.
Then, by applying the bias voltage to a secondary transfer roller (not shown), the full-color toner image is transferred to a sheet (secondary transfer).

After the primary transfer, the photosensitive drum (5) is neutralized by a static eliminator (not shown), cleaned by a rubbing roller (10) and a cleaning blade (9), and remains on the surface of the photosensitive drum (5). Untransferred toner is removed.
After the secondary transfer, untransferred toner remaining on the surface of the transfer belt (1) is removed by the cleaning blade (12).

FIG. 2 is an enlarged schematic view showing one of the four image forming units (4).
As shown in FIG. 2, at the time of image formation, the rubbing roller (10) rotates in the opposite direction to the photosensitive drum (5), and collects untransferred toner remaining on the surface of the photosensitive drum (5).

At this time, the rubbing roller (10) carries the collected toner on the surface and rotates more slowly than the photosensitive drum (5). As a result, the surface of the photosensitive drum (5) is polished with the toner, and the conductive foreign matter such as the water discharge product of the discharge product adhering to the surface of the photosensitive drum (5) can be removed.
An abrasive such as fine particle titanium oxide is added to the toner as an external additive, and the photosensitive drum (5) is polished mainly by the external additive.

  When the adhesion of foreign matter to the photosensitive drum (5) increases due to the operating environment or the state of the toner, or when the abrasiveness decreases due to a decrease in the toner additive, etc., the foreign matter adherence action is slid. Since it exceeds the polishing action of the rubbing roller (10), the surface state of the photosensitive drum (5) deteriorates and the surface frictional resistance value rises, but the frictional resistance value detecting means (concentration sensor (13)) determines a predetermined value. When a larger frictional resistance value is detected, the rotation ratio of the rubbing roller (10) to the photosensitive drum (5) is changed so as to increase the abrasiveness.

  To change the rotation ratio so as to improve the polishing properties, the rubbing roller (10) is rotated faster than the photoconductive drum (5) in the direction opposite to the photoconductive drum (5) (in the direction of the arrow in FIG. 2). Either the roller (10) is rotated in the same direction as the photosensitive drum (5) (the direction opposite to the arrow in FIG. 2).

  In the former, since the rubbing roller (10) and the photosensitive drum (5) rotate in the opposite direction (arrow direction in FIG. 2), that is, the abutting portions are moved in the same direction. Therefore, it is possible to improve the polishing performance without generating jitter due to uneven rotation or rotational position deviation.

  In the latter, the rubbing roller (10) and the photosensitive drum (5) rotate in the same direction (the reverse direction of the arrow in FIG. 2), that is, the abutting portion moves in the opposite direction. Can be easily obtained.

In any of the above cases, when the frictional resistance value detecting means detects a value larger than the predetermined frictional resistance value, the rotation ratio of the rubbing roller (10) to the photosensitive drum (5) is changed. Since the polishing performance is improved only occasionally, jitter is hardly generated and image disturbance can be prevented.
Further, since the rubbing roller (10) is also provided in a conventional image forming apparatus, no additional members are required.

Next, a method for detecting the frictional resistance value by the frictional resistance value detecting means will be described.
In this embodiment, the frictional resistance value detecting means is a density sensor (13) for detecting the density of a density detection toner image (patch) formed on the transfer belt (1).

FIG. 3 shows an example of the patch.
A patch (21), which is a solid image of three strips shown in FIG. 3A, is formed on the surface of the photosensitive drum (5) and transferred to the transfer belt (1). After cleaning, a patch (22) as a halftone image shown in FIG. 3B is newly formed on the surface of the photosensitive drum (5) and transferred to the transfer belt (1).
The density of the patch (22) transferred to the transfer belt (1) is detected by the density sensor (13).

  When the frictional resistance value on the surface of the photosensitive drum (5) increases, the transfer efficiency decreases, and the toner remains on the electrostatic latent image without being transferred. As a result, the charge memory remains without being completely discharged, and the image density decreases.

  The patch (22) forms a uniform halftone image shown in FIG. 3B when the frictional resistance value on the surface of the photosensitive drum (5) is not increased, but when the frictional resistance value increases. As shown in FIG. 3C, the charged memory (21 ′) remains in the portion corresponding to the patch (21), and the density of the patch (22) in the portion decreases.

The frictional resistance value on the surface of the photosensitive drum (5) is calculated based on the decrease in the density of the charging memory (21 ′) portion detected by the density sensor (13).
Specifically, as in an example shown in Table 1, the relationship between the patch density decrease and the frictional resistance value is examined in advance, and the detected patch density is collated with the value in Table 1 to obtain the frictional resistance value.
The relationship between the patch density reduction and the frictional resistance value varies depending on the operating environment, the toner used, and the like, and is not limited to Table 1.

  Originally, the density sensor (13) is used to detect the patches (21) and (22) in the image forming apparatus and determine the image forming conditions such as the exposure condition and the developing condition. Since it is also used as the resistance value detecting means, the frictional resistance value on the surface of the photosensitive drum (5) can be detected without adding any member.

The patch density detection is not limited to detecting the density of the patch formed on the surface of the transfer belt (1), but may be the one detecting the density of the patch formed on the surface of the photosensitive drum (5). However, the former is preferred.
Particularly in the color image forming apparatus, in the latter case, a density sensor is required for each color toner photosensitive drum (5), and the number of parts increases. In the former case, the patch transferred to the transfer belt (1) is increased. This is because the density is detected and only one density sensor (13) is required, and the number of parts may be small.

The detection of the frictional resistance value on the surface of the photosensitive drum (5) is preferably performed during non-image formation.
Even when an increase in the frictional resistance value is detected, even if the rotation ratio of the rubbing roller (10) with respect to the photosensitive drum (5) is changed and influenced by fluctuations in the rubbing load, no image forming operation is performed. This is because no jitter occurs.

The detection of the frictional resistance value on the surface of the photosensitive drum (5) is preferably performed when the apparatus power is turned on.
This is because the frictional resistance value on the surface of the photosensitive drum (5) can be detected before the image forming operation is performed, so that it is possible to prevent image disturbance.

The detection of the friction resistance value on the surface of the photosensitive drum (5) is preferably performed after a predetermined number of image forming processes (for example, 30,000 sheets, 50,000 sheets, etc.).
This is because the frictional resistance value on the surface of the photosensitive member can be detected periodically, so that the frictional resistance value on the surface of the photosensitive drum (5) can be properly maintained.

  The present embodiment is an image forming apparatus that forms a color image, but is not limited to this, and the present invention can also be applied to a monochrome image forming apparatus.

  The present invention is suitably used for an image forming apparatus employing an electrophotographic system such as a copying machine, a printer, or a fax machine.

1 is a schematic diagram illustrating an image forming unit of an image forming apparatus according to the present invention. 1 is a schematic view showing an image forming unit of an image forming apparatus according to the present invention. FIG. 3 is a diagram illustrating an example of a density detection toner image in the image forming apparatus according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Intermediate transfer belt 5 Photosensitive drum 10 Rub roller 13 Density sensor 21 Patch 22 Patch

Claims (7)

A photosensitive member; an intermediate transfer member disposed opposite to the photosensitive member to which a toner image formed on the surface of the photosensitive member is transferred; and a slider for carrying the toner on the surface and polishing the surface of the photosensitive member for cleaning. An image forming apparatus having a rubbing roller and a friction resistance value detecting means for detecting a friction resistance value of the surface of the photoreceptor,
The frictional resistance value detecting means detects a frictional resistance value based on a density of a density detection toner image formed on the surface of the photoreceptor or the intermediate transfer body;
An image forming apparatus, wherein a rotation ratio of the rubbing roller to the photosensitive member is changed when a value larger than a predetermined friction resistance value is detected by the friction resistance value detecting means.   The rubbing roller rotates in a direction opposite to the photosensitive member in a direction slower than the rotational speed of the photosensitive member, and the photosensitive member is detected when a value larger than a predetermined frictional resistance value is detected by the frictional resistance value detecting unit. The image forming apparatus according to claim 1, wherein the image forming apparatus rotates in a direction opposite to a rotation speed faster than a rotation speed of the photoconductor.   The rubbing roller rotates in a direction opposite to the photosensitive member in a direction slower than the rotational speed of the photosensitive member, and the photosensitive member is detected when a value larger than a predetermined frictional resistance value is detected by the frictional resistance value detecting unit. The image forming apparatus according to claim 1, wherein the image forming apparatus rotates in the same direction as the image forming apparatus.   4. The image forming apparatus according to claim 1, wherein the frictional resistance value detecting unit is a density detection sensor that detects a density of a density detection toner image formed on the surface of the intermediate transfer member. apparatus.   The image forming apparatus according to claim 1, wherein the detection by the frictional resistance value detection unit is performed during non-image formation.   6. The image forming apparatus according to claim 5, wherein the non-image forming time is when the apparatus power is turned on.   The image forming apparatus according to claim 5, wherein the non-image formation is after a predetermined number of image forming processes have been performed.

Images