JP3174418B2 - Image forming apparatus and control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrostatic recording process, such as an electrostatic copying machine and an electrostatic printer.

[0008]

2. Description of the Related Art (1) Conventionally, a plurality of image forming units are provided,
Various color image forming apparatuses have been proposed in which toner images of different colors are formed in the respective image forming units, and the toner images are sequentially superimposed and transferred on the same transfer material. Among them, various color image forming apparatuses are frequently used. This is a multi-color electrophotographic color copying machine.

Referring to FIG. 23, an example of the above-described color copying apparatus will be described. First to fourth image forming units Pa, Pb, Pc, Pd are juxtaposed in the apparatus body of the color electrophotographic copying apparatus. , A photosensitive drum 201 serving as a dedicated image carrier
a, 201b, 201c, and 201d. The photosensitive drums 201a, 201b, 201c, 201d
Around the primary chargers 202a, 202b, 202
c, 202d, developing units 203a, 203b, 203c,
203d, and cleaning devices 204a, 204b,
204c and 204d are arranged. In each of the image forming sections Pa, Pb, Pc, and Pd, an endless transfer belt 205 is disposed, and transfer chargers 206a, 206b, 206c, and 206d are disposed therein. Laser beam scanners 207a, 207b, 207b, 207b,
207c and 207d are provided, and irradiate a laser beam modulated according to image information to each drum surface to form a latent image.

In the above configuration, first, the first image forming section P
The photosensitive drum 201a is uniformly charged by the primary charger 202a, and is
07a forms a latent image of a black component in the original image (exposure). The latent image is supplied with black toner by the developing device 203a to be visualized. On the other hand, on the recording material 211 fed from the cassette 208 by the pickup roller 209 and conveyed by the transfer belt 205 via the registration roller 210, a black toner image is transferred by a transfer charger 206a in a transfer section.

Subsequently, while the black toner image is being transferred to the recording material 211, a magenta component color latent image is formed in the second image forming portion Pb, and then the magenta toner is developed by the developing device 203b. The supplied and formed magenta toner image is transferred when the recording material 211 after the transfer in the first image forming unit Pa is conveyed to the transfer unit. Hereinafter, similarly, the third and fourth image forming units Pc
, Pd to form yellow and cyan images, and a yellow toner image and a cyan toner image are transferred to the recording material 211, respectively.

When the image forming process is completed, the image of the transferred image is fixed on the recording material 211 by the fixing device 212. After the image is transferred, each of the photosensitive drums 201a, 201
The toner remaining on b, 201c, and 201d is removed by the cleaning devices 204a, 204b, 204c, and 204d, respectively, to prepare for the next image formation.

(2) Conventionally, an image forming apparatus employing an electrophotographic method has been applied to various apparatuses such as a black-and-white copying machine, a laser beam printer, and a color copying machine. In the electrophotographic method, an electrostatic latent image is formed on a photosensitive drum by a charging process and an exposure process, and the latent image is supplied with a colored toner by a developing process to be visualized, and then the toner image is formed by a transfer process. This is a method in which an image is transferred onto a recording paper and fixed to obtain an image. The toner remaining on the photoreceptor after image transfer is removed from the photosensitive drum by a cleaning process.

In the above-mentioned cleaning process, a blade cleaning system in which an edge made of an elastic member is brought into contact with the photosensitive drum to remove the remaining toner is adopted from the viewpoint of simplification of the apparatus.

[0016]

(1) Further, in the color electrophotographic copying apparatus shown in the above-mentioned prior art (1), foreign matter deposited and adhered on the recording material 211 stored in the cassette 208, Paper dust or the like generated when the surface of the recording material 211 is rubbed by the pickup roller 209 or the registration roller 210 to convey the recording material 211 is particularly deposited on the surface of the photosensitive drum 201a of the first image forming portion Pa. Many easily adhere. Thereby, the photosensitive drum 201a
Paper dust or the like enters between the cleaning blade 213a and the photosensitive drum 201a, which are provided to scrape off the toner remaining on the drum surface in contact with the toner, and the residual toner cannot be removed by the cleaning blade 213a. There is a risk of passing. As a result, FIG.
As shown in (1), there is a possibility that the linear or band-shaped residual toner 214 remains on the photosensitive drum 201a, and the linear or band-shaped defect image 215 is recorded on the recording material 211.

(2) In the blade cleaning method of the image forming apparatus shown in the above-mentioned prior art (2), the cleaning ability is determined by the accuracy of the edge of the cleaning blade, the contact condition, the state of the residual toner on the photosensitive drum ( Many factors are involved, such as, for example, the amount of charge and the degree of cohesion, and the state of contact between the surface of the photosensitive drum and the blade edge.

Of the above factors, the state of contact between the surface of the photosensitive drum and the blade edge is a particularly important factor. If this contact state is not sufficiently ensured, for example, when the contact state is weak, the toner slips through the cleaning blade and remains on the photosensitive drum, and when the contact state is strong, the friction between the cleaning blade and the photosensitive drum increases, causing the blade to be damaged. There is a risk of turning over. Therefore, if the contact between the surface of the photosensitive drum and the cleaning blade becomes nonuniform, there is a possibility that cleaning failure and turning up of the blade may occur.

(1) An object of the present invention is to solve the above-mentioned problem (1) of the prior art and to provide a highly reliable image forming apparatus which can prevent a cleaning failure.

(2) An object of the present invention is to solve the above-mentioned problem (2) of the prior art and provide an image forming apparatus capable of stably maintaining a cleaning operation by a cleaning means such as a cleaning blade for a long period of time. To provide.

[0023]

A typical means for solving the above-mentioned problem (1) of the prior art and applied to the embodiments described below is that a plurality of image carriers and a surface of each image carrier are provided. A plurality of cleaning blades for contacting and cleaning, respectively, wherein the cleaning is provided on the most upstream side in the transport direction of the recording material in the image forming apparatus for sequentially transferring images from the respective image carriers to the recording material. It is characterized in that only the blade can reciprocate in a direction perpendicular to the moving direction of the image carrier while in contact with the surface of the image carrier. Also, a first image carrier, a second image carrier provided downstream of the first image carrier in the transport direction of the recording material, and a first image carrier for cleaning the first image carrier. And a second cleaning blade for cleaning the second image carrier, and sequentially transferring images from the first image carrier and the second image carrier to a recording material. In the image forming apparatus, the first cleaning blade and the second cleaning blade are reciprocally movable in a direction orthogonal to a moving direction of each image carrier in a state of being in contact with the surface of each image carrier. The moving speed of the first cleaning blade is faster than the moving speed of the second cleaning blade. Also, a first image carrier, a second image carrier provided downstream of the first image carrier in the transport direction of the recording material, and a first image carrier for cleaning the first image carrier. A cleaning blade, and a second cleaning blade for cleaning the second image bearing member;
An image forming apparatus that sequentially transfers images from the first image carrier and the second image carrier to a recording material,
The first cleaning blade and the second cleaning blade are reciprocally movable in a direction orthogonal to a moving direction of each of the image carriers while being in contact with the surface of each of the image carriers. The movable distance of the second cleaning blade is longer than the movable distance of the second cleaning blade.

A typical means for solving the above-mentioned problem (2) of the prior art and applied to the embodiments described below is an image carrier and a cleaning means for rubbing and cleaning the surface of the image carrier. A friction charging step of frictionally charging the surface of the image carrier by the cleaning unit, and a detection step of detecting a potential of the surface of the image carrier that has been frictionally charged. A step of determining whether to supply toner between the image carrier and the cleaning unit according to the potential. Further, in a control method for controlling a contact state between an image carrier and a cleaning means for rubbing and cleaning the surface of the image carrier, a friction charging step of frictionally charging the image carrier surface by the cleaning means. An adhering step of adhering toner on the surface of the triboelectrically-charged image carrier, a detecting step of detecting an adhering amount of toner adhering to the surface of the image carrier, and the image forming apparatus according to the detected adhering amount of toner. Determining whether to supply toner between the carrier and the cleaning unit.

[0026]

According to the means (1), only the cleaning blade provided on the most upstream side in the transport direction of the recording material is reciprocated in a direction orthogonal to the moving direction of the image carrier in a state of being in contact with the surface of the image carrier. Since it is configured to be movable, cleaning failure can be prevented without complicating the configuration of the image forming apparatus, and a highly reliable image forming apparatus can be provided. Further, the first cleaning blade and the second cleaning blade can reciprocate in a direction orthogonal to the moving direction of each image carrier while being in contact with the surface of each image carrier. Since the moving speed is configured to be faster than the moving speed of the second cleaning blade, cleaning failure can be prevented without complicating the structure of the image forming apparatus, and a highly reliable image forming apparatus can be provided. can do. Further, the first cleaning blade and the second cleaning blade can reciprocate in a direction orthogonal to the moving direction of each image carrier while being in contact with the surface of each image carrier. Since the movable distance is longer than the movable distance of the second cleaning blade, it is possible to prevent poor cleaning without complicating the configuration of the image forming apparatus, and to provide a highly reliable image forming apparatus. Can be provided.

According to the means (2), a frictional charging step of frictionally charging the surface of the image carrier by the cleaning means;
A detecting step of detecting a potential of the surface of the image carrier triboelectrically charged; and a determining step of determining whether to supply toner between the image carrier and the cleaning unit according to the detected potential. Therefore, it is possible to provide an image forming apparatus capable of stably maintaining the cleaning operation by the cleaning unit for a long period of time. A friction charging step of frictionally charging the surface of the image carrier by the cleaning unit; an adhesion step of adhering toner to the surface of the image carrier that has been frictionally charged; and a detection of detecting the amount of toner adhering to the surface of the image carrier. And a determining step of determining whether to supply toner between the image bearing member and the cleaning unit according to the detected amount of adhered toner. An image forming apparatus that can be stably maintained for a long time can be provided.

[0028]

[First Reference Example]

An image forming apparatus according to a first reference example will be described. The present embodiment will be described using a color electrophotographic copying apparatus having a plurality of image carriers and a plurality of image forming units. FIG.
FIG. 2 is an explanatory sectional view showing the overall configuration of the copying apparatus, and FIG. 2 is an explanatory view showing the width of each part of the process unit.

First, the schematic structure of a color electrophotographic copying machine will be described with reference to FIG. 1. In the inside of the apparatus main body 1, image forming sections Pa, Pb, P having process means therein are built.
c, Pd are arranged in the horizontal direction, and each image forming portion Pa
, Pb, Pc, Pd, a belt drive roller 2
An endless transfer belt 3 is hung around a and 2b. The transfer belt 3 is rotated in the direction of arrow C by rotating the belt drive rollers 2a and 2b in the direction of arrow B by a drive motor (not shown). Reference numerals 4a and 4b denote cassettes which store recording sheets 5 as recording materials. The recording sheets 5 stored in the cassettes 4a and 4b are fed by a pickup roller 6 from the uppermost side. The skew is corrected by the registration roller pair 7, and the image forming units Pa, Pb, Pc, and Pd are corrected.
, And is conveyed onto the transfer belt 3. Reference numeral 8 denotes a transfer belt 3 for transferring the recording sheet 5 from the pair of registration rollers 7.
This is a conveyance guide for guiding the user.

Next, the image forming units Pa, Pb, Pc, P
To explain the configuration of d, the photosensitive drum 9 as an image carrier
a, 9b, 9c, and 9d, and primary chargers 10a, 10b, 10c, and 10d surrounding the processing means, and a developing device
11a, 11b, 11c, 11d, transfer chargers 12a, 12b, 12
c, 12d, cleaning devices 13a, 13b, 13c, 13d,
Pre-exposure light sources 14a, 14b, 14c, and 14d are provided, respectively. Above the photosensitive drums 9a, 9b, 9c, 9d, laser beam scanners 15a, 15b, 15c, 15c are provided.
d is provided.

The above primary chargers 10a, 10b, 10c, 10d
Is to uniformly charge the surface of the drum prior to exposure of the photosensitive drums 9a, 9b, 9c, 9d, and the developing units 11a, 11b, 11c, 11d are exposed to static electricity formed on the surface of the drum. Black, magenta, yellow,
A visible image is formed by attaching each color toner of cyan. The transfer chargers 12a, 12b, 12c, and 12d transfer toner images formed on the photosensitive drums 9a, 9b, 9c, and 9d to the recording sheet 5, and include a cleaning device.
13a, 13b, 13c and 13d are for removing residual toner adhering to the drum surface after image transfer. Pre-exposure light source
14a, 14b, 14c and 14d are photosensitive drums 9a, 9b and 9
The laser beam scanners 15a, 15b, 15c, and 15d have semiconductor lasers, polygon mirrors, fθ lenses, and the like, and receive electric digital image signals and respond to the signals. The modulated laser beam is applied to the photosensitive drums 9a, 9b, 9c, 9d.
In the direction of the generatrix.

Reference numeral 16 denotes a separation charger for separating the recording sheet 5 conveyed on the transfer belt 3, and reference numeral 17 denotes a fixing unit for fixing the transferred image transferred to the recording sheet 5. And a fixing roller 17a having a heating means such as a heater therein and a pressure roller 17b pressed against the fixing roller 17a. Reference numeral 18 denotes a discharge tray for stacking the recording sheets 5 discharged outside the apparatus.

Next, the image forming operation will be described. When an image forming operation start signal is input to the apparatus main body 1, the photosensitive drum 9a starts rotating in the direction of arrow A, and the primary charger 10a is started.
Uniformly charged by laser beam scanner 15
A laser beam modulated by an image signal corresponding to the black component of the original image by a is applied to the drum surface to form an electrostatic latent image (exposure). Next, a black toner is supplied by the developing device 11a to form a toner image that visualizes the latent image.

On the other hand, the recording sheets 5 stored in the cassettes 4a and 4b are fed by a pickup roller 6 and corrected for skew by a registration roller pair 7 which is temporarily stopped. The toner is conveyed onto the transfer belt 3 at a timing with the toner image formed on the transfer belt 3. The recording sheet 5 fed to the transfer belt 3 is subjected to transfer charging by a transfer charger 12a in a transfer section of the image forming section Pa, and a toner image is transferred to the recording sheet 5. The above steps are similarly performed in the image forming units Pb, Pc, and Pd, and the magenta toner image, the yellow toner image, and the cyan toner image are sequentially transferred to the recording sheet 5.

The recording sheet 5 on which the image transfer has been completed is separated from the transfer belt 3 and conveyed to the fixing device 17 while being subjected to AC charge elimination by the separation charger 16 at the left end of the transfer belt 3. Then, the recording sheet 5 on which the image has been fixed by the fixing device 17 is discharged to a discharge tray 18 outside the apparatus.

A fur brush 19 is in contact with a part of the transfer belt 3 as belt cleaning means.
By rotating the fur brush 19 at high speed, the toner accumulated on the transfer belt 3 is removed from the belt.

The image forming units Pa, Pb, P
c, cleaning blades 20a, 20b, 20c, 20d for scraping off residual toner remaining on the surfaces of the photosensitive drums 9a, 9b, 9c, 9d without being transferred to the cleaning devices 13a, 13b, 13c, 13d for Pd. Are arranged to abut the drum surface. As described above, in a color electrophotographic copying apparatus, in order to obtain a higher quality recorded image, the developed toner needs to be reduced to an average particle diameter of 8 μm or less. The cleaning devices 13a, 13b, 13c, and 13d float and easily scatter from the gaps between the cleaning blades 20a, 20b, 20c, and 20d and a cleaner end seal (not shown). 10a, 10b, 10c,
10d and the transfer chargers 12a, 12b, 12c and 12d may be contaminated, resulting in poor charging or deterioration of image quality.

Therefore, the present embodiment is directed to the cleaning device 13.
a, 13b, 13c, 13d cleaning blades 20a, 20d
The cleaning blades 20a, 20b, 20d are used to prevent the residual toner scraped off by the b, 20c, 20d from scattering.
The lengths of c and 20d are changed to the photosensitive drums 9a, 9b, 9c and 9d.
Is configured to be longer than the charging width of all the chargers provided around.

Specifically, as shown in FIG. 2, the width of the cylindrical photosensitive drums 9a, 9b, 9c, 9d in the generatrix direction is W
1. The charging width of the primary chargers 10a, 10b, 10c, 10d is set to W2
, Image forming width W3, developing units 11a, 11b, 11c, 11d
The developing width of the toner by W4, the transfer chargers 12a, 12b,
The charging width by 12c and 12d is W5, and the width of the transfer belt 3 is W
6, if the width of the cleaning blades 20a, 20b, 20c, and 20d is W71, and the width of the cleaner end seal is W8, the width W71 of the cleaning blade is changed to the charging width W2 of the primary charger and the charging width W5 of the transfer charger. By making the length longer (W2 <W71, W5 <W71), contamination of the primary charger and the transfer charger by residual toner scattered from both ends of the cleaning blades 20a, 20b, 20c and 20d can be reduced.
Therefore, contamination of the primary chargers 10a, 10b, 10c, and 10d and the transfer chargers 12a, 12b, 12c, and 12d can be prevented, and defective charging and deterioration of image quality can be prevented.

In the present embodiment, the primary charger and the transfer charger are shown as the chargers provided around the photosensitive drum. However, even when a cleaning auxiliary charger (not shown) is provided, these chargers may be used. This is effective when the length of the cleaning blade is longer than the charging width.

Second Embodiment Next, another example of the image forming apparatus will be described with reference to FIG. Since the schematic configuration of the image forming apparatus is the same as that of the first embodiment, the same members are denoted by the same reference numerals and description thereof will be omitted.

In this embodiment, the cleaning blades 20a, 20
The length W72 of b, 20c, 20d is changed to the primary chargers 10a, 10b,
10c, 10d charging width W2 and transfer chargers 12a, 12b, 12
The transfer belt 3 is configured to be longer than the charging width W5 of c and 12d and the width W6 of the transfer belt 3 (W3 <W4 <W2 <W6).
≤ W72, W3 <W4 <W5 <W6 ≤ W72). That is, the transfer belt 3 is made of polyethylene to ensure that the recording sheet 5 on the belt is attracted and to efficiently transfer the toner images formed on the photosensitive drums 9a, 9b, 9c, 9d to the recording sheet 5. Terephthalate (PET) and PV
It is composed of a thin film sheet made of a polymer resin such as DF, polycarbonate and polyurethane. When the scattered toner adheres to the transfer belt 3 made of the thin film sheet and the accumulation proceeds, the attached and accumulated toner cannot be removed even by the fur brush 19 provided in contact with the transfer belt 3, and the transfer is performed. Deformation of belt film,
There was a risk of damage and poor transfer.

In this embodiment, the length of the cleaning blade W72 is made longer than the width W6 of the transfer belt, so that the scattering of the toner from the cleaning device is reduced, and the scattered toner adheres and accumulates on the transfer belt 3. Can be prevented.

Third Embodiment Next, another example of the image forming apparatus will be described with reference to FIG. Since the schematic configuration of the image forming apparatus is the same as that of the first reference example, the same members are denoted by the same reference numerals and description thereof will be omitted.

In this embodiment, the cleaning blade 20a,
The length W73 of 20b, 20c, 20d is changed to the primary chargers 10a, 10d.
b, 10c, 10d, the charging width W2 and the transfer chargers 12a, 12b,
In addition to the charging width W5 of 12c and 12d and the width W6 of the transfer belt 3, the width W of the photosensitive drums 9a, 9b, 9c and 9d in the generatrix direction is obtained.
It is configured to be longer than 1. That is, when the length W73 of the cleaning blades 20a, 20b, 20c, and 20d is shorter than the width W1 of the photosensitive drums 9a, 9b, 9c, and 9d, the toner scattered from the ends of the cleaning blades is cleaned on the surface of the photosensitive drum. The scattered toner adhering to the photosensitive drum also adheres to the vicinity of the blade end, and after a long period of use, the scattered toner starts to scatter inside the vicinity of the cleaning blade end due to the influence of the air flow in the apparatus. There is a possibility that the end of the primary charger located on the downstream side in the drum rotation direction will be contaminated, causing poor charging.

Therefore, the cleaning blades 20a, 20
The length W73 of the photosensitive drums 9a, 9b, 9
By making the width c1, 9d longer than the width W1, it is possible to prevent scattered toner from remaining on the surface of the photosensitive drum, and to prevent contamination of various chargers and the transfer belt 3 even after long-term use.
It is possible to provide a highly reliable image forming apparatus free from charging failure and image failure.

In FIG. 4, reference numeral 21 denotes the photosensitive drum 9a,
9b, 9c, and 9d, the photosensitive drum 9
Reference numeral 23 denotes a drum flange having a gear 22 for rotatingly driving a, 9b, 9c, 9d, 23 denotes a drum shaft, and 24 denotes a cleaner end seal.

[First Embodiment] Next, an image forming apparatus according to an embodiment of the present invention to which the means (1) is applied will be described. The present embodiment will be described using a color electrophotographic copying apparatus having a plurality of image carriers and a plurality of image forming units. FIG. 5 is an explanatory cross-sectional view showing the overall configuration of the copying apparatus, FIG. 6 is an explanatory view showing the configuration of the image forming unit Pa, and FIG. 7 is an explanatory view showing the configuration of the cleaning device.

First, the schematic structure of a color electrophotographic copying machine will be described with reference to FIG. 5. In the apparatus main body 41, image forming sections Pa, Pb, P having process means therein are built.
c, Pd are arranged in the horizontal direction, and each image forming portion Pa
, Pb, Pc, and Pd are provided with belt driving rollers 42 below.
An endless transfer belt 43 is hung around a and b. The transfer belt 43 is rotated in the direction of arrow C by rotating the belt drive rollers 42a and 42b in the direction of arrow B by a drive motor (not shown). 44a and 44b are cassettes which store recording sheets 45 as recording materials. The recording sheets 45 stored in the cassettes 44a and 44b are fed from the uppermost side by a pickup roller 46. The skew is corrected by the pair of registration rollers 47, and the image forming units Pa, Pb, Pc, and Pd are corrected.
, And is conveyed onto the transfer belt 43. A transfer belt 43 transfers the recording sheet 45 from the registration roller pair 47.
This is a conveyance guide for guiding the user.

Next, the image forming units Pa, Pb, Pc, P
Explaining the configuration of d, the photosensitive drum 49 as an image carrier
a, 49b, 49c, and 49d, and primary chargers 50a, 50b, 50c, and 50d around which a process means is formed, and a developing device
51a, 51b, 51c, 51d, transfer chargers 52a, 52b, 52
c, 52d, cleaning devices 53a, 53b, 53c, 53d,
Pre-exposure light sources 54a, 54b, 54c and 54d are provided, respectively. Above the photosensitive drums 49a, 49b, 49c, 49d, laser beam scanners 55a, 55b, 55c, 55
d is provided.

The primary chargers 50a, 50b, 50c, 50d
Is for uniformly charging the surface of the drum prior to exposure of the photosensitive drums 49a, 49b, 49c, 49d. The developing units 51a, 51b, 51c, 51d are exposed to static electricity formed on the surface of the drum. Black, magenta, yellow,
A visible image is formed by attaching each color toner of cyan. The transfer chargers 52a, 52b, 52c, and 52d transfer toner images formed on the photosensitive drums 49a, 49b, 49c, and 49d to the recording sheet 45, and include a cleaning device.
53a, 53b, 53c and 53d are for removing residual toner adhering to the drum surface after image transfer. Pre-exposure light source
54a, 54b, 54c and 54d are photosensitive drums 49a, 49b and 49
The laser beam scanners 55a, 55b, 55c, and 55d have a semiconductor laser, a polygon mirror, an fθ lens, and the like, and receive an electric digital image signal and respond to the signal. The modulated laser beam is applied to the photosensitive drums 49a, 49b, 49c, 49d.
In the direction of the generatrix.

Reference numeral 56 denotes a separation charger for separating the recording sheet 45 conveyed on the transfer belt 43, and reference numeral 57 denotes a fixing unit for fixing the transferred image transferred to the recording sheet 45. And a fixing roller 57a having a heating means such as a heater therein and a pressure roller 57b pressed against the fixing roller 57a. Reference numeral 58 denotes a discharge tray for stacking the recording sheets 45 discharged outside the apparatus.

Next, the image forming operation will be described. When an image forming operation start signal is input to the apparatus main body 41, the photosensitive drum 49a starts rotating in the direction of arrow A, and the primary charger 50a is started.
Uniformly charged by the laser beam scanner 55
A laser beam modulated by an image signal corresponding to the black component of the original image by a is applied to the drum surface to form an electrostatic latent image (exposure). Next, a black toner is supplied by the developing device 51a to form a toner image in which the latent image is visualized.

On the other hand, the recording sheet 45 stored in the cassettes 44a and 44b is fed by a pickup roller 46, and after the skew is corrected by a registration roller pair 47 which is temporarily stopped, the photosensitive drum 49a The toner is conveyed onto the transfer belt 43 at a timing with the toner image formed on the transfer belt 43. Recording sheet sent to the transfer belt 43
Reference numeral 45 denotes a transfer section of the image forming section Pa, which is subjected to transfer charging by the transfer charger 52a, and the toner image is transferred to the recording sheet 45. The above steps are similarly performed in the image forming units Pb, Pc, and Pd, and the magenta toner image, the yellow toner image, and the cyan toner image are sequentially transferred to the recording sheet 45.

The recording sheet 45 on which the image transfer has been completed is separated from the transfer belt 43 and conveyed to the fixing device 57 while being subjected to AC static elimination by the separation charger 56 at the left end of the transfer belt 43. Then, the recording sheet 45 on which the image has been fixed by the fixing device 57 is discharged to a discharge tray 58 outside the apparatus.

A fur brush 59 is in contact with a part of the transfer belt 53 as belt cleaning means.
By rotating the fur brush 59 at high speed, the transfer belt
It is configured to remove the toner accumulated on the belt 53 from the belt.

Incidentally, the image forming units Pa, Pb, P
c, cleaning blades 60a, 60b, 60c, 60d for scraping residual toner remaining on the surfaces of the photosensitive drums 49a, 49b, 49c, 49d without being transferred to the cleaning devices 53a, 53b, 53c, 53d for Pd. Are arranged to abut the drum surface. As described above, the recording sheet 45 stored in the cassettes 44a and 44b is provided on the surface of the photosensitive drum 49a of the image forming unit Pa closest to the feeding unit.
Foreign matter that has been deposited and adhered on the surface, paper dust generated when the sheet surface is rubbed by the pickup roller 46 and the registration roller pair 47 when the recording sheet 45 is conveyed, and the like are easily attached to the cleaning blade. When it enters between the photosensitive drum 49a and the photosensitive drum 49a, cleaning failure is likely to occur.

When an image is formed with a plurality of color toners such as cyan, magenta, yellow, and black as shown in this embodiment, the color toner in each developing unit is provided in each developing unit in each image forming unit. In order to prevent the reproducibility from being deteriorated, the addition of an external additive such as zinc stearate, cerium oxide, or strontium titanate as a lubricant is restricted, so that the residual toner and paper dust adhering to the photosensitive drum 49a are restricted. Cleaning blade 60a
Removal may be more difficult.

Therefore, in the present embodiment, the cleaning device 53a of the image forming portion Pa closest to the feeding portion in terms of distance.
In addition, a reciprocating operation mechanism for reciprocating in a direction perpendicular to the paper surface of FIG. 5 in a state where the cleaning blade 60a is in contact with the photosensitive drum 49a is provided.

That is, since the fibrous foreign matter such as paper powder is most likely to adhere to the surface of the photosensitive drum 49a of the image forming unit Pa closest to the feeding unit in terms of distance, the image forming unit Pa In the case where these foreign substances enter between the cleaning blade 60a and the photosensitive drum 49a, the cleaning blade holder is driven by a drive motor (not shown).
The cleaning blade 61 is reciprocated in the direction perpendicular to the paper surface along the reciprocating shaft 62a, and the cleaning blade 60a is mechanically reciprocated in the direction perpendicular to the paper surface with the cleaning blade 60a in contact with the surface of the photosensitive drum 49a. Foreign matter that has entered between the photosensitive drum 60a and the photosensitive drum 49a can be positively removed, and an image defect such as a cleaning defect can be restored to a normal state, and a highly reliable image forming apparatus can be obtained. it can.

Hereinafter, referring to FIGS. 6 and 7, the image forming portion Pa and the cleaning device 53 which are closest in distance to the feeding portion will be described.
The configuration of a will be described. As shown in FIG. 6, the cleaning device 53a provided in the image forming section Pa has a cleaning blade 60a made of urethane rubber adhered to a cleaning blade holder 61 made of sheet metal. It is in contact with 49a. As shown in FIG. 7, the cleaning blade holder 61 is fixed to a reciprocating shaft 62a by a fixing member 63, and a spring 64 is provided at one end (the right side in the drawing) of the reciprocating shaft 62a so as to fit. The other end (left side in the drawing) of the reciprocating shaft 62a is in contact with the inclined side surface of the trapezoidal gear 65. The trapezoidal gear 65 is rotatably driven by a gear 66 driven by a drive motor (not shown) to reciprocate the reciprocating shaft 62a in the directions indicated by arrows F and R by a distance L corresponding to the difference in gear width of the trapezoidal gear 65. Is configured. Reference numeral 67 denotes a cleaner end seal provided to contact the photosensitive drum 49a in order to prevent scattering of waste toner from inside the cleaning device 53a.

According to an experiment conducted by the inventor based on the above configuration, four colors of cyan, magenta, yellow, and black were obtained.
In a copying apparatus having image forming units Pa, Pb, Pc, and Pd for the colors and having an OPC photosensitive drum and a two-component developing device as photosensitive drums, the image forming unit Pa closest to the feeding unit in distance is used. In the cleaning device 53a, the cleaning blade 60a is moved at a speed of 10 mm / sec.
With a reciprocating movement mechanism that only reciprocates,
The occurrence of cleaning failure in the image forming portion Pa was significantly reduced.

According to the above configuration, the cleaning device of the image forming unit closest to the feeding unit in distance is provided with the reciprocating operation mechanism for reciprocating the cleaning blade while keeping the cleaning blade in contact with the photosensitive drum. Failure can be prevented, and a highly reliable image forming apparatus can be obtained.

Second Embodiment Next, another example of the image forming apparatus shown in the first embodiment will be described with reference to FIGS. Since the schematic configuration of the color electrophotographic copying apparatus according to this embodiment is almost the same as that of the first embodiment, the same members are denoted by the same reference numerals and description thereof will be omitted.

In this embodiment, the image forming units Pa, Pb, Pc, and C, for four colors of cyan, magenta, yellow, and black are used.
All cleaning devices 53a, 53b, 53 equipped with Pd
c and 53d are provided with a reciprocating operation mechanism. That is, as shown in FIG. 8, the photosensitive drum 49 of each image forming unit
a, 49b, 49c, and 49d, cleaning blades 60a arranged in contact with the drum surface to remove fibrous foreign matters such as residual toner and paper dust adhering to the drum surface.
When the cleaning blades 60b, 60c, and 60d are provided, the cleaning blades 60a, 60b, 60c, and 60d are reciprocated in the direction perpendicular to the paper surface along the reciprocating shafts 62a, 62b, 62c, and 62d in the same configuration as in the first embodiment. That is, it is configured to be.

The reciprocating movement speed of the cleaning blade 60a of the cleaning device 53a provided in the image forming section Pa closest to the feeding section in the image forming sections is set to the other image forming sections Pb and Pb. The reciprocating movement speed of the cleaning blades 60b, 60c, 60d of the cleaning devices 53b, 53c, 53d mounted on Pc, Pd is configured to be higher. As shown in FIG. 9, this is deposited and adhered on the recording sheet 45 stored in the cassettes 44a and 44b on the surface of the photosensitive drum 49a of the image forming section Pa closest to the feeding section in terms of distance. Foreign matter or recording sheet
Paper powder and the like generated when the sheet surface is rubbed by the pickup roller 46 and the registration roller pair 47 when the sheet 45 is conveyed easily adhere to the photosensitive drum. (Na> Nb.gtoreq.Nc.gtoreq.Nd), it is necessary to increase the ability to remove foreign matter such as paper dust from the surface of the photosensitive drum as the image forming unit is closer to the feeding unit. That's why.

As shown in FIG. 10, according to the experiment performed by the present inventor, as the reciprocating speed at which the cleaning blade is reciprocally moved while being in contact with the photosensitive drum is increased, the paper from the drum surface by the cleaning blade is increased. It was found that the powder removing ability was improved. Therefore, in this embodiment, the reciprocating movement speed of the cleaning blade is increased (va> vb ≧ vc) in the image forming portion Pa closer to the feeding portion where the amount of foreign matter such as paper dust adhered to the photosensitive drum is larger.
.Gtoreq.vd), so that the ability to remove foreign matter adhering to the photosensitive drum is enhanced.

The structure for changing the reciprocating movement speed of the cleaning blades 60a, 60b, 60c, 60d in the image forming sections Pa, Pb, Pc, Pd is the same as that of the first embodiment shown in FIG. This can be easily realized by changing the rotation speed of the motor for each image forming unit, changing the number of teeth of the gear 66, and the like.

According to the above configuration, the setting condition of the reciprocating movement speed of the cleaning blade of each image forming unit is changed according to the distance from the feeding unit, and the reciprocating movement of the cleaning blade is closer to the image forming unit closer to the feeding unit. By increasing the speed, the efficiency of removing foreign matter attached to the photosensitive drum in each image forming unit can be improved. Further, in the image forming section remote from the feeding section, the structure of the cleaner end seal as a measure for preventing toner scattering required during the high-speed reciprocating movement operation can be simplified.

Third Embodiment Next, another example of the image forming apparatus shown in the first embodiment will be described with reference to FIG. Since the schematic configuration of the color electrophotographic copying apparatus according to this embodiment is almost the same as that of the first embodiment, the same members are denoted by the same reference numerals and description thereof will be omitted.

In this embodiment, the reciprocating movement distance L of the cleaning blade 60a of the cleaning device 53a provided in the image forming unit Pa closest to the feeding unit in terms of distance is set to the other image forming units Pb, Pc and Pd. Cleaning equipment equipped
53b, 53c, 53d cleaning blades 60b, 60c,
It is configured to be longer than the reciprocating movement distance L of 60d. That is, as shown in FIG. 11, according to the experiment of the present inventor, the longer the moving distance L for reciprocating the cleaning blade with the cleaning blade attached to the photosensitive drum, the longer the paper dust from the photosensitive drum by the cleaning blade. It was found that the removal ability was improved. Therefore, in this embodiment, the reciprocating movement distance of the cleaning blade is increased (La> Lb ≧ L in an image forming portion closer to the feeding portion having a larger amount of foreign matter such as paper dust on the photosensitive drum.
c.gtoreq.Ld), so that the ability to remove foreign matter adhering to the photosensitive drum is enhanced.

The structure for changing the reciprocating movement distance of the cleaning blades 60a, 60b, 60c, 60d in the image forming sections Pa, Pb, Pc, Pd is the same as that shown in FIG. 7 of the first embodiment. It can be realized only by changing the dimension L of the trapezoidal gear 65 for moving the blade, and the configuration of the image forming apparatus can be simplified even when all the image forming units are provided with a cleaning blade reciprocating movement mechanism.

According to the above configuration, the setting condition of the reciprocating movement of the cleaning blade of each image forming unit is changed according to the distance from the feeding unit, and the reciprocating movement distance of the cleaning blade is closer to the image forming unit closer to the feeding unit. By increasing the length, the efficiency of removing foreign matter adhering to the photosensitive drum in each image forming unit can be improved.

[Fourth Embodiment] Next, an image forming apparatus according to an embodiment of the present invention to which the means (2) is applied will be described. This embodiment will be described using an electrophotographic copying machine as an image forming apparatus. FIG. 12 is a cross-sectional explanatory diagram showing the entire configuration of the copying apparatus, FIG. 13 is an explanatory diagram showing an operation sequence of the process unit, FIG. 14 is a graph showing the relationship between the linear pressure of the cleaning blade on the photosensitive drum and the potential of the photosensitive drum, FIG. 15 is a graph showing the relationship between the number of prints and frictional charging potential, FIG. 16 is an explanatory diagram showing an operation sequence of the process unit in the frictional force measurement mode, and FIG. 17 is a flowchart showing a frictional force measurement operation in the frictional force measurement mode. is there.

First, the schematic structure of the copying apparatus will be described with reference to FIG. 12. Reference numeral 71 denotes a photosensitive drum as an image carrier, for example, a photosensitive drum such as selenium, amorphous Si, and an organic photosensitive member. Reference numeral 72 denotes a primary charger using corona discharge for uniformly charging the photosensitive drum 71.The primary charging unit including the primary charger 72 includes a discharge wire surrounded by a shield, and a scorotron provided with a grid at an opening. A constant current high voltage power supply unit 73 for applying a high voltage to the discharge wire and a constant voltage high voltage power supply unit 74 for applying a high voltage to the grid
It is connected to the.

Reference numeral 75 denotes a laser beam scanner for scanning a laser beam in the generatrix direction of the photosensitive drum 71 to form an electrostatic latent image. 76 is a developing device for visualizing the electrostatic latent image formed on the photosensitive drum 71, for example, using a one-component magnetic toner, forming a thin toner layer on a developing sleeve,
The developing bias (AC +
DC) is applied to develop a latent image, or a so-called jumping development method, or a thin toner layer is formed on a developing sleeve using a two-component developer composed of a high-resistance carrier and a toner, and the photosensitive drum 71 is not contacted with this. Developing bias (AC + DC) alternating between the photosensitive drum 71 and the developing sleeve in close proximity to
Is applied using a two-component magnetic brush system.

Reference numeral 77 denotes a transfer charger for transferring the toner image on the photosensitive drum 71 to a recording sheet. As in the case of the primary charger 72, a constant-current high-voltage power supply unit 78 for applying a high voltage to a discharge wire is provided. It is connected to the. Reference numeral 79 denotes a cleaning device that removes toner remaining on the photosensitive drum 71 after the transfer process, and mechanically scrapes the cleaning drum 79a made of an elastic material such as urethane by bringing the cleaning blade 79a into contact with the photosensitive drum 71 in the counter direction. A blade cleaning method of cleaning the drum surface by force is employed. Reference numeral 80 denotes a pre-exposure light source for making the potential of the photosensitive drum 71 uniform prior to primary charging, and 81 a fixing device for fixing the toner image transferred to the recording material. Reference numeral 85 denotes a CPU for controlling voltages applied to the constant current high voltage power units 73 and 78 and the constant voltage high voltage power unit 74.

FIG. 13 shows an operation sequence of the process unit during image formation. The photosensitive drum 71 is a primary charger 72
, And is exposed to light by a laser beam scanner 75 to form an electrostatic latent image. The electrostatic latent image is supplied with toner by a developing device 76 to be visualized.
On the other hand, the recording sheet 83 fed from the cassette 82 is corrected for skew by the temporarily stopped registration roller pair 84, and is conveyed in synchronization with the toner image.
The toner image on the photosensitive drum 71 is transferred onto the recording sheet 83 by the transfer charger 77. Recording sheet after image transfer
In the reference numeral 83, the transferred image is fixed by the fixing device 81 and is discharged out of the apparatus.

FIG. 14 is a graph showing the relationship between the linear pressure of the cleaning blade on the photosensitive drum and the potential of the photosensitive drum. The linear pressure of the cleaning blade 79a is a value representing the setting of the cleaning device 79. For example, if the linear pressure of the cleaning blade 79a is high, the friction between the cleaning blade 79a and the photosensitive drum 71 increases, and if it is too high, the blade is turned up. If the linear pressure is low, the scraping force of the residual toner on the photosensitive drum 71 will be insufficient, and if it is too low, cleaning failure will occur. Therefore, the linear pressure of the cleaning blade 79a needs to be set to an appropriate value.

The actually used linear pressure largely depends on the type of toner to be cleaned. That is, the toner having a small particle diameter has a large charge of the toner,
Since the adhesive force to 71 is large, a large linear pressure is required.
For example, a toner having an average particle diameter of 8 μm has a charge of 20 to 40.
about μC / g, blade linear pressure 10-30g / cm
Is needed. Although a frictional force with the photosensitive drum is reduced by adding a lubricant or the like to the toner, there is a problem that color reproducibility is reduced when the toner is a color toner or the like.

The surface of the photosensitive drum 71 is charged by friction between the surface of the photosensitive drum 71 and the cleaning blade 79a. As a result, the photosensitive drum 71 and the cleaning blade 79a are charged.
The friction force with 79a changes. By utilizing this relationship, the frictional force between the photosensitive drum 71 and the cleaning blade 79a can be estimated by measuring the surface potential of the photosensitive drum 71. The actual frictional force can be measured from a driving torque for rotating the photosensitive drum 71 or the like.

The magnitude of the frictional force was measured under various conditions by the above measuring method. As a result, the friction force becomes
For example, it is determined based on conditions such as blade pressure and the like, and changes depending on a change in the contact state between the cleaning blade 79a and the photosensitive drum 71. FIG. 15 shows the triboelectric potential in a durable use. Curve A indicates the triboelectric potential at a position where toner is always supplied, and curve B indicates the potential at a position where toner is not supplied. It is presumed that the frictional charging state of the cleaning blade 79a differs depending on the presence or absence of the toner. Due to the change in the frictional charging state, the photosensitive drum 71 and the cleaning blade 79a at the position where the toner is not supplied.
When the frictional force increases with a certain value or more, blade turning occurs. On the other hand, it can be presumed that the frictional force can be reduced by supplying the toner to the drum surface.

The present invention has been made in view of the above results. After the photosensitive drum 71 is uniformly discharged, the photosensitive drum 71 is frictionally charged by the cleaning blade 79a, and the potential distribution in the axial direction is measured. Thus, the frictional force of the cleaning blade 79a is measured. Thereafter, the photosensitive drum 71 is exposed by a laser beam scanner 75 as a frictional force reducing means to form a belt-like electrostatic latent image on the drum surface, and this is developed by a developing device 76 to supply toner to a cleaning device 79. To reduce the frictional force between the photosensitive drum 71 and the cleaning blade 79a.

The frictional force measuring operation will be described with reference to the operation sequence of the electrophotographic process shown in FIG. First,
When the frictional force measurement mode is instructed, the photosensitive drum 71 is driven and the photosensitive drum 71 is uniformly discharged by the primary charger 72 and the pre-exposure light source 80. Next, the photosensitive drum surface from which the charge has been uniformly removed is frictionally charged by rubbing with a cleaning blade 79a, and the potential distribution on the drum surface at this time is measured. Since the charging potential of the photosensitive drum 71 changes depending on the number of rotations, it must be measured on the drum surface having the same number of rotations.

In this embodiment, as a means for detecting the state of the potential distribution in the longitudinal direction of the photosensitive drum 71, a surface voltmeter 88 is used.
(See FIG. 12), and the surface electrometer 88 is connected to the photosensitive drum.
The potential unevenness in the longitudinal direction of the photosensitive drum 71 can be measured by measuring the potential by the moving means for moving the photosensitive drum 71 in the longitudinal direction. The photosensitive drum 71 and the cleaning blade
The frictional charging potential with 79a is generally wide, and can be sufficiently detected with a resolution of about 5 to 10 mm at an expected angle of a normal surface electrometer 88. The step of moving the surface voltmeter 88 is preferably about half the expected angle.

After the measurement of the frictional force, the pre-exposure light source 80 removes the charged charges, stops the rotation of the photosensitive drum 71, and terminates the frictional force measuring operation.

Next, the frictional force measuring operation in the frictional force measuring mode will be described with reference to the flowchart shown in FIG. First, in step S1, a frictional force measurement mode of the cleaning device 79 is designated by an operation unit (not shown), thereby starting a measurement operation. Next, proceeding to step S2, as described above, the photosensitive drum 71 is rotated to move the surface voltmeter 88 in the longitudinal direction of the photosensitive drum 71, and the surface potential is measured. The maximum value Vmax of the potential is calculated.

Next, the process proceeds to step S3, and if the maximum value Vmax of the frictional charging potential is larger than the fixed value VO, the process proceeds to step S4 to execute the above-described frictional force reducing means.
That is, in step S4, the photosensitive drum 71 is exposed by the laser beam scanner 75 to form a belt-like electrostatic latent image on the drum surface, and the electrostatic latent image is developed by the developing device 76 to remove toner from the photosensitive drum 71 and the cleaning blade. Supply between 79a (toner application mode). It is desirable to set the width of the electrostatic latent image as narrow as possible in order to prevent contamination in the apparatus. The width of the latent image can be optimally set according to the maximum value Vmax of the triboelectric potential. And
In step S5, the surface potential meter 88 is moved again in the longitudinal direction of the photosensitive drum 71 to measure the surface potential, and the maximum value Vmax of the triboelectric potential is calculated from the measured potential distribution.

Next, proceeding to step S6, if the maximum value Vmax of the triboelectric potential is larger than the fixed value VO, proceeding to step S7 to instruct the display unit (not shown) of the operation unit to replace the cleaning blade 79a. Is displayed.

According to the above configuration, the cleaning blade
The frictional force between the cleaning blade 79a and the photosensitive drum 71 is reduced by detecting the frictional charging potential of the photosensitive drum 71 caused by the rubbing of the photosensitive drum 71 with the photosensitive drum 71. A stable cleaning operation can be maintained for a long time.

Fifth Embodiment Next, another example of the image forming apparatus of the fourth embodiment will be described with reference to FIG.
This will be described with reference to FIGS. Since the schematic configuration of the electrophotographic copying apparatus is the same as that of the fourth embodiment, the same members are denoted by the same reference numerals and description thereof will be omitted. In FIG.
In this embodiment, the potential distribution of the photosensitive drum 71 frictionally charged by the rubbing of the cleaning blade 79a is visualized by supplying toner by a developing device 76, and the visible image is a toner adhesion sensor which is an optical detecting means. 86 to detect. By scanning the detection means 86 in the longitudinal direction of the photosensitive drum 71, it is possible to detect the unevenness of the toner adhesion amount and the unevenness of the potential.

The specific structure of the toner adhesion sensor 86 will be described with reference to FIG. A light emitting element 86a is provided inside the toner adhesion sensor 86. For example, a double-sided light emitting LED having a wavelength of 960 nm (preferably having a light collecting property to reduce the detection surface) and an optical transparent window 86 are provided.
b, and a light receiving element 86c for detecting the amount of light emitted from the light emitting element 86a and reflected in accordance with the amount of adhered toner.

Next, the frictional force measuring operation of this embodiment will be described with reference to FIG. 20 with reference to the operation sequence of the electrophotographic process. First, when the frictional force measurement mode is instructed, the photosensitive drum 71 is driven and the photosensitive drum 71 is uniformly discharged by the primary charger 72 and the pre-exposure light source 80. Next, the photosensitive drum surface from which the charge has been uniformly removed is cleaned with a cleaning blade 79a.
The toner is adhered to the drum surface charged to the developing unit 76 at this time, and the amount of toner adhered is detected by the toner adhesion sensor 86.

According to the above configuration, the potential unevenness of the photosensitive drum 71 is detected by replacing the unevenness in the potential of the photosensitive drum 71 with the toner adhesion amount. Therefore, the unevenness in the potential of the photosensitive drum 71 can be amplified at the toner attaching stage. That is, by setting the developing bias to a potential having a large gradient in the characteristic of the amount of toner adhesion with respect to the surface potential of the photosensitive drum 71, it is possible to amplify the potential non-uniformity when replacing it with the amount of toner adhesion. The frictional force between the cleaning blade 79a and the photosensitive drum 71 can also be detected by capturing the frictional force as the toner amount in this way, and the above-described frictional force reducing means can be executed.

Sixth Embodiment Next, another example of the image forming apparatus of the fourth embodiment will be described with reference to FIG.
This will be described with reference to FIG. Since the schematic configuration of the electrophotographic copying apparatus is the same as that of the fourth embodiment, the same members are denoted by the same reference numerals and description thereof will be omitted.

In this embodiment, the cleaning method shown in FIG.
As shown in FIG. 7, a fur brush cleaning method is adopted in which the fur brush 87 is brought into rotational contact with the photosensitive drum to remove residual toner attached to the drum surface after image transfer. In FIG. 21, the photosensitive drum moves in the direction of the arrow.
The fur brush 87 comes into contact with 71 and rotates in the opposite direction to remove the residual toner. The cleaning performance is determined by the material and the number of rotations of the fur brush 87, the amount of penetration into the photosensitive drum 71, and the like. It has been found that there is a correlation between the cleaning performance and the magnitude of the potential at which the photosensitive drum 71 is frictionally charged due to the friction between the fur brush 87 and the photosensitive drum 71. That is, if the cleaning performance is weak, cleaning failure occurs,
If the cleaning performance is too high, the photosensitive drum 71 is scraped and the fur brush 87 is deteriorated. In general, even if the fur brush 87 has an optimum cleaning performance, the cleaning performance gradually decreases with use. In this embodiment, the cleaning performance is determined by the photosensitive drum 71 and the fur brush 87.
Detected by the potential of the photosensitive drum 71 due to frictional charging of
The recovery process is performed to improve the cleaning performance of the cleaning device 79.

Next, the operation of measuring the amount of triboelectric charge in the frictional force measurement mode will be described with reference to the flowchart shown in FIG. First, in step S11, a frictional force measurement mode of the cleaning device 79 is designated by an operation unit (not shown), thereby starting a measurement operation. Next, the process proceeds to step S12, where the photosensitive drum
By rotating the surface potential meter 88 in the longitudinal direction of the photosensitive drum 71 by rotating the surface potential meter 71, the surface potential is measured, and the minimum value Vmin of the triboelectric potential is calculated from the measured potential distribution.

Next, the process proceeds to step S13, and if the minimum value Vmin is smaller than the fixed value V1, the process proceeds to step S14 to execute the above-described cleaning recovery process. That is, in step S14, after increasing the rotation speed of the fur brush 87, the process proceeds to step S15, where the surface potential meter 88 is moved again in the longitudinal direction of the photosensitive drum 71, and the surface potential is measured. From the obtained potential distribution, the minimum value Vmin of the triboelectric potential is calculated.

Next, the process proceeds to step S16, and if the maximum value Vmin is smaller than the fixed value V1, the process proceeds to step S17 to display on the display unit (not shown) of the operation unit an instruction to replace the fur brush 87.

According to the above configuration, the recovery performance of the cleaning device can be performed by detecting the cleaning performance of the fur brush 87 based on the charged potential of the photosensitive drum 71 due to frictional charging between the fur brush 87 and the photosensitive drum 71. In addition, a stable cleaning operation that does not cause defective cleaning can be maintained for a long time.

[0102]

According to the present invention, only the cleaning blade provided on the most upstream side in the conveying direction of the recording material reciprocates in the direction orthogonal to the moving direction of the image carrier in a state of being in contact with the surface of the image carrier. Since the configuration is possible, cleaning failure can be prevented without complicating the configuration of the image forming apparatus, and a highly reliable image forming apparatus can be provided. Further, according to the present invention, the first cleaning blade and the second cleaning blade can reciprocate in a direction orthogonal to a moving direction of each of the image carriers while being in contact with the surface of each of the image carriers. First
Since the moving speed of the cleaning blade is faster than the moving speed of the second cleaning blade, it is possible to prevent defective cleaning without complicating the structure of the image forming apparatus, and to obtain a highly reliable image. A forming device can be provided. Further, according to the present invention, the first cleaning blade and the second cleaning blade can reciprocate in a direction orthogonal to a moving direction of each of the image carriers while being in contact with the surface of each of the image carriers. Since the movable distance of the first cleaning blade is configured to be longer than the movable distance of the second cleaning blade, it is possible to prevent poor cleaning without complicating the configuration of the image forming apparatus.
A highly reliable image forming apparatus can be provided.

Further, according to the present invention, a friction charging step of frictionally charging the surface of the image bearing member by the cleaning means, a detecting step of detecting the potential of the surface of the image bearing member which has been frictionally charged, And a determining step of determining whether to supply toner between the image bearing member and the cleaning unit, so that the cleaning operation by the cleaning unit can be stably maintained for a long period of time. An image forming apparatus can be provided. Further, according to the present invention, a friction charging step of frictionally charging the surface of the image carrier by the cleaning unit, an adhesion step of adhering toner to the surface of the frictionally charged image carrier, A detection step of detecting the amount of adhesion;
A determining step of determining whether or not to supply toner between the image carrier and the cleaning unit in accordance with the detected amount of adhered toner, so that the cleaning operation by the cleaning unit is performed for a long period of time. And an image forming apparatus that can be stably maintained.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view illustrating an entire configuration of a copying apparatus according to a first reference example.

FIG. 2 is an explanatory diagram showing the width of each part of a process unit according to a first reference example.

FIG. 3 is an explanatory diagram showing the width of each part of a process unit according to another example (second reference example) of the first reference example.

FIG. 4 is an explanatory diagram showing the width of each part of a process unit according to another example (third reference example) of the first reference example.

FIG. 5 is an explanatory sectional view showing the entire configuration of the copying apparatus according to the first embodiment.

FIG. 6 is an explanatory diagram illustrating a configuration of an image forming unit Pa according to the first embodiment.

FIG. 7 is an explanatory diagram illustrating a configuration of the cleaning device according to the first embodiment.

FIG. 8 is an explanatory cross-sectional view showing the overall configuration of a copying apparatus according to another example (second embodiment) of the first embodiment.

FIG. 9 is a graph showing the amount of paper dust attached to each image forming unit according to another example (second embodiment) of the first embodiment.

FIG. 10 is a graph showing the relationship between the reciprocating movement speed of the cleaning blade and the amount of paper dust removed from the drum surface according to another example (second embodiment) of the first embodiment.

FIG. 11 is a graph showing a relationship between a reciprocating movement distance of a cleaning blade and an amount of paper dust removed from a drum surface according to another example (third embodiment) of the first embodiment.

FIG. 12 is an explanatory sectional view showing the entire configuration of a copying apparatus according to a fourth embodiment.

FIG. 13 is an explanatory diagram showing an operation sequence of a process unit according to a fourth embodiment.

FIG. 14 is a graph showing the relationship between the linear pressure of the cleaning blade on the photosensitive drum and the potential of the photosensitive drum according to the fourth embodiment.

FIG. 15 is a graph showing the relationship between the number of prints and the triboelectric potential according to the fourth embodiment.

FIG. 16 is an explanatory diagram showing an operation sequence of a process unit in a frictional force measurement mode according to the fourth embodiment.

FIG. 17 is a flowchart showing a frictional force measuring operation in a frictional force measuring mode according to the fourth embodiment.

FIG. 18 is an explanatory cross-sectional view showing the entire configuration of a copying apparatus according to another example (fifth embodiment) of the fourth embodiment.

FIG. 19 is an explanatory diagram showing a configuration of a toner adhesion amount detection sensor according to another example (fifth embodiment) of the fourth embodiment.

FIG. 20 is an explanatory diagram showing an operation sequence of a process unit in a frictional force measurement mode according to another example (fifth embodiment) of the fourth embodiment.

FIG. 21 is an explanatory diagram showing a fur brush cleaning operation according to another example (sixth embodiment) of the fourth embodiment.

FIG. 22 is a flowchart showing a triboelectric potential measurement operation in a frictional force measurement mode according to another example (sixth embodiment) of the fourth embodiment.

FIG. 23 is an explanatory diagram of a conventional copying apparatus.

FIG. 24 is an explanatory diagram of a conventional recorded image.

[Explanation of symbols]

Pa, Pb, Pc, Pd: image forming unit 1, 41: apparatus main body 2a, 2b, 42a, 42b: belt drive roller 3, 43: transfer belt 4a, 4b, 44a, 44b, 82: cassette 5, 45, 83 ... Recording sheet 6,46 ... Pickup roller 7,47,84 ... Registration roller pair 8,48 ... Transport guide 9a, 9b, 9c, 9d, 49a, 49b, 49c, 49d, 71
... Photosensitive drums 10a, 10b, 10c, 10d, 50a, 50b, 50c, 50d, 72
... Primary chargers 11a, 11b, 11c, 11d, 51a, 51b, 51c, 51d, 76
... Developers 12a, 12b, 12c, 12d, 52a, 52b, 52c, 52d, 77
... Transfer chargers 13a, 13b, 13c, 13d, 53a, 53b, 53c, 53d, 79
... Cleaning devices 14a, 14b, 14c, 14d, 54a, 54b, 54c, 54d, 80
... Pre-exposure light source 15a, 15b, 15c, 15d, 55a, 55b, 55c, 55d, 75
… Laser beam scanners 16, 56… Separation chargers 17, 57, 81… Fixers 17a, 57a… Fixing rollers 17b, 57b… Pressurizing rollers 18, 58… Discharge trays 19, 59, 87… Fur brushes 20a, 20b, 20c, 20d, 60a, 60b, 60c, 60d, 79
a ... Cleaning blade 21 ... Drum flange 22, 66 ... Gear 23 ... Drum shaft 24, 67 ... Cleaner end seal 61 ... Cleaning blade holder 62 ... Reciprocating shaft 63 ... Fixing member 64 ... Spring 65 ... Trapezoidal gear 73, 78 ... Constant Current high voltage power supply unit 74… Constant voltage high voltage power supply unit 85… CPU 86… Toner adhesion sensor 88… Surface potentiometer

Continuation of the front page (56) References JP-A-64-40875 (JP, A) Japanese Utility Model Application Hei 3-92670 (JP, U) Japanese Utility Model Application Utility Model Hei 3-65173 (JP, U) (58) Fields investigated (Int) .Cl. ⁷ , DB name) G03G 21/10-21/12 G03G 15/01-15/01 117 G03G 15/02-15/02 103 G03G 15/16-15/16 103 G03G 15/00 550 G03G 21 / 16-21/18 G03G 15/00 303 G03G 21/00 370-540

Claims (11)

(57) [Claims] 1. An image carrier comprising: a plurality of image carriers; and a plurality of cleaning blades for cleaning the respective image carriers in contact with the surfaces of the respective image carriers, and sequentially transferring images from the respective image carriers to a recording material. In the image forming apparatus, only the cleaning blade provided on the most upstream side in the transport direction of the recording material is capable of reciprocating in a direction orthogonal to the moving direction of the image carrier while in contact with the surface of the image carrier. An image forming apparatus comprising: A first image bearing member, a second image bearing member provided downstream of the first image bearing member in a recording material conveying direction, and a cleaning of the first image bearing member. First
Cleaning blade, and a second cleaning blade for cleaning the second image carrier,
An image forming apparatus for sequentially transferring an image from the first image carrier and the second image carrier to a recording material, wherein the first cleaning blade and the second cleaning blade are provided on the surface of each image carrier. Can move back and forth in a direction orthogonal to the moving direction of each of the image carriers while contacting with the first cleaning blade.
An image forming apparatus which is faster than the moving speed of the cleaning blade. 3. A first image carrier, a second image carrier provided downstream of the first image carrier in a conveying direction of a recording material, and cleaning of the first image carrier. First
Cleaning blade, and a second cleaning blade for cleaning the second image carrier,
An image forming apparatus for sequentially transferring an image from the first image carrier and the second image carrier to a recording material, wherein the first cleaning blade and the second cleaning blade are provided on the surface of each image carrier. The image carrier can be reciprocated in a direction perpendicular to the moving direction of the image carriers, and the movable distance of the first cleaning blade is longer than the movable distance of the second cleaning blade. Characteristic image forming apparatus. 4. A control method for controlling a contact state between an image carrier and a cleaning means for rubbing and cleaning the surface of the image carrier, wherein the cleaning means frictionally charges the surface of the image carrier. A charging step, a detecting step of detecting a potential of the surface of the image carrier that is frictionally charged, and a determination of determining whether to supply toner between the image carrier and the cleaning unit according to the detected potential. And a control method. 5. The control method according to claim 4, wherein after the toner is supplied between the image carrier and the cleaning unit, the friction charging step and the detection step are performed again. 6. The control method according to claim 5, further comprising a second determining step of determining whether or not a display for instructing replacement of the cleaning unit is to be displayed on a display unit according to the potential detected again. . 7. The image forming apparatus according to claim 4, further comprising a charge removing step for removing charge from the surface of the image bearing member, wherein the friction charging step is performed on the surface of the image bearing member that has been removed in the charge removing step. Control method. 8. A control method for controlling a contact state between an image carrier and a cleaning means for rubbing and cleaning the surface of the image carrier, wherein the cleaning means frictionally charges the surface of the image carrier. A charging step, an adhering step of adhering toner on the surface of the triboelectrically charged image carrier, a detecting step of detecting an adhering amount of toner adhering to the surface of the image carrier, and a detecting step for detecting the adhering amount of toner. A step of determining whether to supply toner between the image carrier and the cleaning unit. 9. The control method according to claim 8, wherein after the toner is supplied between the image carrier and the cleaning unit, the friction charging step, the attaching step, and the detecting step are performed again. 10. A method according to claim 9, further comprising the step of determining whether or not a display for instructing replacement of said cleaning means is to be displayed on a display unit in accordance with the amount of toner adhesion detected again. Control method. 11. The image forming apparatus according to claim 8, further comprising a charge elimination step for eliminating charge on the surface of the image bearing member, wherein the frictional charging step is performed on the surface of the image bearing member on which the charge is eliminated in the charge eliminating step. Control method.