JPH0659606A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the excessive cutting of the photosensitive layer of a photoreceptor by filming removing action through which a larger quantity of a cleaning agent than the time of copying is stored in a cleaning domain in a cleaning device to remove filming as the photoreceptor is made to function. CONSTITUTION:A film thickness detecting sensor and a voltage sensor are provided opposite to the surface of a photoreceptor 18, and the rubbing force of the photoreceptor 18 caused by the cleaning agent of the cleaning sleeve 32 of a cleaning device 27 and the executing time of filming removing action are regulated according to the output of the above sensors. In concrete terms, in the case where the reducing of the thickness of a film is detected, and the lowering of a charged voltage caused by a charger is detected, the rotating speed of the cleaning sleeve 32 is accelerated, or a gap between a doctor plate section 36 and the cleaning sleeve 32 is lessened to weaken the rubbing force, or to shorten the executing time of the film removing action.

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 such as a copying machine, a facsimile and a printer, and more particularly, to an image forming apparatus for performing a filming removing operation on a latent image carrier. The present invention relates to an improvement for preventing excessive scraping of the latent image bearing layer of the latent image bearing member.

[0002]

2. Description of the Related Art An image forming apparatus for removing filming on a latent image carrier has a latent image carrier layer formed on a substrate and a toner image formed on the latent image carrier layer during image formation. A latent image carrier, an agent carrier which is placed opposite to the latent image carrier and which conveys an agent composed of a magnetic material while carrying it by magnetic force, and the latent image carrier is slid by the agent on the agent carrier. A means for changing the rubbing force for rubbing, and performing the operation of removing filming on the latent image carrier by making the rubbing force stronger than during image formation at times other than during image formation. Known (see, for example, JP-A-3-155588, JP-A-3-121482, and JP-A-3-7976).

[0003]

According to the above configuration,
It is also possible to rub the latent image bearing member with the agent on the agent bearing member supported by magnetic force, thereby removing filming and making the surface of the latent image bearing member a mirror surface. However, it has been discovered that the filming removal force is relatively strong, so that the latent image bearing layer of the latent image bearing member may be thinned at an early stage. In order to solve this problem, it is possible to set various conditions so that the filming removal force becomes relatively weak, but if the filming removal frequency is set to a high level, it may be necessary to set only a weak filming removal force. In some cases, the filming cannot be completely removed and the image quality is deteriorated.

The present invention has been made in view of the above problems, and an object of the present invention is to detect the condition of a latent image carrier and to obtain an appropriate filming removing force according to this condition. An object of the present invention is to provide an image forming apparatus capable of adjusting the filming removal force.

[0005]

In order to achieve the above object, the present invention provides a latent image bearing layer on a substrate, and a toner image is formed on the latent image bearing layer during image formation. A latent image bearing member, and an agent bearing member that is placed opposite to the latent image bearing member and that conveys an agent made of a magnetic substance while magnetically carrying the agent.
A means for changing the rubbing force for rubbing the latent image carrier by the agent on the agent carrier, and making the rubbing force stronger than that during image formation at times other than during image formation. In an image forming apparatus for removing filming on the latent image carrier,
Detecting means for detecting the condition of the latent image carrier, and adjusting means for adjusting the rubbing force during the removing operation and the time for performing the removing operation according to the output of the detecting means are provided. Here, the agent and the agent carrier may be provided exclusively for filming removal, or in a developing device or a cleaning device, in an image forming apparatus including such an agent and the agent carrier, the developing device is used. Alternatively, the agent and the agent carrier in the cleaning device may also be used for removing filming. Also,
As the detection means, a thickness detection means for detecting the thickness of the latent image bearing layer or a potential detection means for detecting the surface potential of the latent image bearing member is used. Further, when this thickness detecting means is used, it is between a detection operation position where the detection means comes into contact with or approaches the surface of the latent image carrier and a retracted position which is farther from the surface than the detection operation position. It is desirable to provide contacting / separating means for moving. Further, the contacting / separating means is configured such that the thickness detecting means takes the detection operation position when the surface of the latent image carrier is stopped and takes the retracted position while the surface of the latent image carrier is moving. It is desirable to do. Further, the contacting / separating means brings a part of the mounting member, to which the thickness detecting means is mounted, into contact with the latent image carrier or a position reference portion other than the latent image carrier to perform positioning at the detecting operation position. It is desirable to configure it to do. Further, it is desirable that an elastic member be attached to the portion of the thickness detecting means or the attaching member to which the thickness detecting means is attached facing the latent image carrier.

[0006]

The present invention detects the condition of the latent image carrier and, in accordance with the result, the rubbing force for rubbing the latent image carrier by the agent on the agent carrier during the filming removal operation and the removal operation. It acts to adjust the time to do.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electrophotographic color copying machine which is an image forming apparatus will be described below. In this copying machine, the one used in the cleaning device is used as the agent for removing filming and the agent carrier. FIG. 1 is a schematic configuration diagram of a color copying machine according to the embodiment. First, the overall configuration will be described. In this copying machine, first, a document (not shown) placed on the contact glass 10 is illuminated and scanned by moving the illumination device 11 together with the first mirror 12 to the right in the figure. The scanning light image at this time is incident on the lens 15 via the second mirror 13 and the third mirror 14 that move in the same direction, and then the fourth mirror 16 and the filter device 17 are provided.
The image is projected onto a drum-shaped photoconductor 18 which is an example of the configuration of the latent image carrier. The filter device 17 has a plurality of color separation filters, and these filters can be rotated by 90 degrees so that they can be freely selected and used. Then, with one of these filters, for example, an optical image of a blue component is first taken out, and this optical image is image-projected onto the photoconductor 18 which has already been uniformly charged by the charger 19. As a result, an electrostatic latent image is formed on the photoconductor. A yellow developing device 21Y, a magenta developing device 21M, and a cyan developing device 21C are provided below the photoconductor 18, and the electrostatic latent image is first converted into a toner image by the yellow toner of the yellow developing device 21Y. A transfer paper, which is an example of the transfer material sent from the paper supply unit 23, is wound around and held on the transfer drum 22, and the toner image is transferred by the transfer charger 20 onto the wound transfer paper. Similarly, by using each of the other filters, the magenta magenta toner image and the cyan cyan toner image formed on the photoconductor are respectively transferred and superposed on the transfer paper. When obtaining the black toner image, the electrostatic latent image is visualized by the black toner of the black developing device 21B. In the case of black exposure, an ND filter may be used as a filter, or such a filter may not be used. 50Y, 50M, 50C and 50B in FIG.
The developing sleeve of each developing device is rotationally driven in the direction of the arrow, carries the developer on its peripheral surface and conveys the developer, and sequentially forms each electrostatic latent image on the photoconductor 18 into a toner image. After the toner image is transferred, the transfer paper is separated from the transfer drum 22 by the separation charger 24 and the separation claw 25, and the separated transfer paper passes through the fixing device 26 and is ejected outside the machine as copy paper. On the other hand, the toner remaining on the photoconductor 18 after the transfer of the toner image of each color is removed by the cleaning device 27 each time.

Next, the general structure and operation of the cleaning device 27 will be described. FIG. 2 shows the details of the magnetic brush cleaning device 27. Photoconductor 1
8 rotates in the direction of the arrow, and the photoconductor 1
A pre-cleaning charger 28 is provided on the downstream side of the transfer portion, which is a contact portion between the transfer drum 8 and the transfer drum 22, so as to face the photoconductor 18. In addition, a cleaning sleeve 32 made of a conductive non-magnetic material such as aluminum having a plurality of magnets 31 provided therein is disposed downstream of the pre-cleaning charger 28. The individual magnets are denoted by P _{1 to} P ₆ , and the magnetic poles of the respective magnets on the side facing the cleaning sleeve 32 are alternately opposite in polarity. The cleaning sleeve 32 constitutes one example of the constitution of the agent carrier, and in this embodiment, the sleeve 32 is used.
However, the fixed magnet 31 is rotationally driven in the arrow direction (clockwise direction) by a drive motor not shown in FIG. Reference numeral 40 denotes a cleaning case of the cleaning device 27. The side of the case 40 facing the photoconductor 18 is opened, and a part of the cleaning sleeve 32 is exposed at this opening. It is opposite to 18.

After the transfer of the toner image, when the toner left on the photosensitive member 18 comes to the portion of the pre-cleaning charger 28, corona discharge by the pre-cleaning charger 28 makes it easy to clean the toner particles. , With a certain polarity (positive in the example of the figure).

On the other hand, on the peripheral surface of the cleaning sleeve 32, a cleaning agent C composed of a magnetic carrier for cleaning and toner is carried by the magnetic force of the magnet 31, and a magnetic brush is formed by the carrier. More specifically, the cleaning agent C is composed of powders of a carrier and a toner that are frictionally charged with different polarities from each other, and particles of the carrier made of a magnetic material are carried on the sleeve 32 by magnetic force, and the toner is electrostatically attached to the particles. Are adhered to. It is well known that there are toners consisting of only toner particles and toners containing additives. The cleaning agent C is conveyed in the rotation direction of the cleaning sleeve 32 by the rotation of the cleaning sleeve 32 and rubs against the surface of the photoconductor 18 facing the cleaning sleeve 32 in the cleaning area X.

The residual toner charged by the pre-cleaning charger 28 is removed by the cleaning sleeve 3.
When it comes to the cleaning area X opposed to 2, the residual toner is transferred to a cleaning carrier having a negative charge on the cleaning sleeve 32 to which a bias voltage (negative in the example in the figure) is applied by the power supply 41. It adheres with electrostatic attraction and mechanical scavenging force. In this way, the toner on the photoconductor 18 is removed and cleaning is performed.

Next, the carrier to which the toner adheres is carried by the magnetic force on the cleaning sleeve 32 to form a magnetic brush, and is conveyed, for example, a bias made of metal and having a predetermined polarity (negative in the illustrated example). The voltage is applied to the toner collecting roller 33 by the power source 42, and the toner collecting roller 33 contacts the roller 33 at a position facing the toner collecting roller 33. At this time, the toner electrostatically adheres to the collecting roller 33. At this time, a certain amount of toner remains on the cleaning sleeve 32 side, and this becomes the toner in the cleaning agent C. The toner collecting roller 33 rotates clockwise, and a collecting blade 34 made of an elastic rubber or an elastic metal plate is brought into contact with the roller 33, whereby the toner adhered on the collecting roller 33 is moved downward. Be scraped off. The scraped toner is discharged to the outside of the cleaning device by the discharging screw conveyor 35.

On the other hand, the cleaning agent C on the cleaning sleeve 32 is further conveyed to the doctor blade section 3
6, the cleaning agent C has a thickness of 0.5, for example.
It is regulated to be about 2.0 mm, the cleaning area X is entered again, and this operation is repeated.

The above-mentioned doctor blade portion 36 is a structure of a regulating means for regulating the amount of the cleaning agent conveyed to the cleaning area X between the photoconductor 18 and the cleaning sleeve 32 so that proper cleaning is performed. It is an example. As described above, the copying machine shown in FIGS. 1 and 2 conveys the photoconductor 18 on which the toner image is formed during the image forming operation, the photoconductor 18 which is placed opposite to the photoconductor 18 and which carries the cleaning agent C by magnetic force. And a doctor blade portion 36 that regulates the amount of the cleaning agent C conveyed to the region X between the photoconductor 18 and the sleeve 32.

Specific examples of the respective elements of the copying machine shown in FIGS. 1 and 2, especially the cleaning device 27 thereof are as follows. (1) Magnetic velocity density in the magnetic pole of the magnet 31 shown by the symbol P ₁ in FIG. 2: 1000 to 1100 gauss (2) Similarly, magnetic velocity density in the magnetic pole of the magnet 31 shown by the symbol P ₂ : 1200 to 1300 gauss (3) ) Position of the magnet P ₁ forming the main pole: A line L connecting the cleaning sleeve 32 and the center of the photoconductor 18 is used as a reference, and an angle formed by this reference line and a line 1 passing through the center of the cleaning sleeve 32 is θM. Positive (+) as shown in Fig. 2,
When it was determined to be negative (−), the magnet P ₁ was arranged in the range of −2 ° to + 8 °. (4) Bias voltage applied to the cleaning sleeve 32 from the power supply 41: DC-150V (5) Bias voltage applied to the toner recovery roller 33 from the power supply 42: DC-500V (6) The cleaning sleeve 32 during normal cleaning operation Linear velocity (peripheral velocity) (V _S ): 300 mm / sec (7) Linear velocity (peripheral velocity) (V _P ) of ordinary photoconductor 18: 20
0mm / sec (8) the center value of the gap between the cleaning sleeve 32 and the doctor blade portion _{36 (G D): 0.8mm (} 9) the center value of the gap of the cleaning sleeve 32 and the photosensitive member 18 (G _P): 1 0.0 mm (10) Concentration of toner with respect to carrier of cleaning agent C: 0.5 to 2% by weight (11) Charge amount of toner in cleaning agent C: 10
80 μc / g (12) Carrier shape of cleaning agent C: irregular

As described above, the copying machine and its cleaning device 27
The general structure of the cleaning device 27 has been described above.
Of the toner that has moved to the 2 side, toner with a low charge amount,
Despite the charging function of the pre-cleaning charger 28, the toner that has not been positively charged may float away from the cleaning sleeve 32 and may adhere to the photoreceptor again. Further, not limited to the cleaning device 27,
Toner floating from the developing devices 21Y, 21M, 21C, 21B and the like, paper powder of transfer paper or additives contained therein adhere to the surface of the photoconductor 18. The toner, paper dust, etc. thus attached may adhere to the surface of the photoconductor in the form of a thin film over time. This is the filming phenomenon described above, and when this occurs, uneven sensitivity occurs on the photoconductor 18, resulting in uneven density of the toner image formed on the surface thereof or scumming. Therefore, it is necessary to remove the filming formed on the photoreceptor at an early stage or prevent the filming from occurring.

In the illustrated copying machine, a cleaning device 27 is used to remove filming. That is, at a time other than the time of image formation for forming the toner image on the photoconductor 18 as described above, a larger amount of the cleaning agent C than that during the normal cleaning operation is applied to the photoconductor 1.
8 and the cleaning sleeve 32 are fed into the area X, and the photosensitive member 18 is operated in a state where a large amount of the cleaning agent C is filled in the area X as compared with the cleaning operation. By doing so, the agent is accumulated in the cleaning area X, and the carrier particles in the cleaning agent C are
The surface of the rotating photoconductor 18 is strongly rubbed, and the filming formed on the photoconductor surface can be scraped off. That is, the contact pressure and the coefficient of friction between the magnetic brush made of the cleaning agent C and the surface of the photoconductor are increased, whereby the rubbing force of the magnetic brush on the surface of the photoconductor is increased and the effect of removing filming can be enhanced. is there.
In this way, the filming removal operation can be executed for a predetermined time other than the image forming operation to remove the filming on the photoconductor 18 or prevent the filming from occurring. Even if the drum-shaped photoconductor 18 has some eccentricity, a cleaning agent is accumulated in the cleaning area X and removes filming. Therefore, uneven filming removal does not occur.

As in the cleaning device 27 shown in the figure, in the cleaning device in which the magnet 31 is fixed and the cleaning sleeve 32 is rotationally driven to convey the cleaning agent C on the sleeve 32, cleaning to the cleaning area X is performed as described above. In order to increase the feeding amount of the agent C, the rotation speed of the cleaning sleeve 32 may be slower than that during the normal cleaning operation. If the linear velocity of the cleaning sleeve 32 becomes slower, the centrifugal force acting on the cleaning agent C carried on it becomes weaker, and the cleaning agent C is strongly attracted to the surface side of the cleaning sleeve 32. As a result, the doctor blade 36
The amount of the cleaning agent C passing through the sheet increases, and the amount of the cleaning agent C conveyed to the cleaning area X also increases.

According to experiments, the cleaning sleeve 32
The linear velocity of v _S of, when the linear velocity of the photoconductor 18 was v _P, when conveying a large amount of cleaning agent C in a cleaning area X can be scraped off filming, i.e. slow the linear velocity of the cleaning sleeve 0 <| v _S
By setting v _S and v _P so as to satisfy / v _P | <0.5 (the rotation speed of the cleaning sleeve 32 is, for example, about 10 rpm), filming can be scraped off efficiently. In the normal cleaning operation, for example, | v
Each linear velocity is set so as to satisfy _S / v _P |> 0.5.

Next, a more specific operation example will be described with reference to FIG. In FIG. 4, when the main switch of the copying machine is turned on, the photoconductor cleaning operation starts. That is, the photoconductor drive motor operates to start rotation of the photoconductor 18, and the cleaning sleeve drive motor operates to rotate the cleaning sleeve 32 clockwise in FIG. As a result, as described above, the photoconductor 1
The toner remaining on the toner 8 adheres to the cleaning agent C on the cleaning sleeve 32, more precisely, its carrier, and the photoconductor 18 is cleaned.

After the above cleaning operation is performed for a predetermined time, the filming removal operation is started. At this time, the rotation speed of the cleaning sleeve 32 is set to a low speed (0 <| v _S / v _P | <0.5) according to the eighth configuration example, and the amount of the cleaning agent conveyed to the cleaning area X is increased. The filming on the photoconductor 18 is scraped off. As an example of the v _S / v _P during low-speed rotation of the cleaning sleeve 32, v _S
/ V _P = 17 mm / sec / 300 mm / sec = 0.06. FIG. 3 shows an example of the relationship between the linear velocity v _S of the cleaning sleeve 32 and the amount of the cleaning agent conveyed to the cleaning area X (FIG. 2). The transport amount of the agent is increased, and the filming removal effect is enhanced.

Further, T shown in FIG. 4 is a rising time from the end of the above-described photosensitive member cleaning operation until each element of the copying machine, for example, the fixing device rises to a predetermined temperature, and in the example of FIG. Although the filming removal operation is performed only for the time indicated by t in the above, the filming removal operation may be performed over the desired range of the rising time T, or the whole thereof. This is
This is the meaning of the “extendable range of the filming removal operation” shown inside. When the rising time T elapses,
The copying machine is ready for copying, and the image forming operation (copying operation) is started by turning on the copy switch. During a series of image forming operations and at the end thereof as shown in FIG. 4, a photoreceptor cleaning operation is performed, and then a filming removal operation is performed. That is, the cleaning sleeve 32 is rotated at a low speed to increase the amount of the cleaning agent conveyed to the cleaning area X.

As can be seen from the above example, the filming removal operation can be executed at an appropriate time other than the time of image formation.

As described above, at a time other than the image forming operation for forming a toner image on the photoconductor 18, an amount of cleaning agent capable of scraping off the filming of the photoconductor 18 is cleaned with the photoconductor 18. By transporting the film to the area X between the sleeve 32 and the sleeve 32, filming can be effectively removed. In that case, no special member for removing filming is required, and the cost of the apparatus can be reduced.

By the way, filming has a different susceptibility depending on the copy frequency and the like. Therefore, assuming a situation in which filming is most likely to occur, uniformly increase the surface rubbing force of the photoconductor by the magnetic brush during the filming removal operation and / or increase the execution time of the filming removal operation. If the setting is made longer, the film surface itself may be excessively scraped and the photosensitive layer abruptly thinned to significantly shorten the life of the photosensitive member 18 when filming is relatively small due to a low copy frequency. is there. On the contrary, assuming a situation where the occurrence of filming is small, uniformly reduce the surface rubbing force of the photoconductor by the magnetic brush during the filming removal operation,
If the execution time of the filming removal operation is set and / or the filming cannot be removed completely, the image quality may be deteriorated due to the filming.

Therefore, in this embodiment, the photoconductor 18
The surface condition of the film is detected, and the filming removal force or the execution time of the filming removal operation in the filming removal operation is adjusted so that the appropriate filming operation according to the situation is detected. For example, when it is detected from the surface condition of the photoconductor 18 that the photosensitive layer is excessively scraped by the filming removal operation, the filming removal force in the filming removal operation is adjusted to be small. Instead of or in addition to this, the execution time of the filming removal operation is adjusted to be short.

First, the detection of the surface condition of the photoconductor 18 will be described. As such a detecting means, a film thickness detecting sensor for detecting the film thickness of the photosensitive layer can be used. FIG. 5A is an explanatory view of the mounting position, and FIG. 5B is an explanatory view of the support mechanism. In FIG. 5A, the film thickness detection sensor 60 is attached so that the detection head is close to the surface of the photoconductor. In the illustrated example, the black developing device 2
Although it is installed on the upstream side of 1B, it is not limited to this. The film thickness detection sensor 60 of this example is shown in FIG.
As shown in (b), three photoconductor drums 18 are provided at substantially equal intervals in the width direction. Each film thickness detection sensor 60 is fixed to a holder 61 which is a mounting member, and a detection operation position where the holder 61 contacts or approaches the film thickness detection sensor 60 with the surface of the photoconductor and a retracted position separated from the surface of the photoconductor. It is connected to a driving member 62, which is composed of, for example, a solenoid for moving between. Also,
Both ends of the holder 61 are abutting portions 18a having a diameter larger than that of a central portion formed at both ends of the photosensitive drum 18,
It faces 18a. When the drive member 62 moves the film thickness detection sensor 60 to the detection operation position, both ends of the holder 61 come into contact with the abutting portions 18a, 18a serving as reference positions to position the film thickness detection sensor 60. It functions as a reference member. An elastic member 63 is provided around each film thickness detection sensor 60 to prevent the film thickness detection sensor 60 from colliding with the surface of the photoconductor when the drive member 62 moves from the retracted position to the detection position. Has been. It is desirable that the film thickness detection sensor 60 detects the film thickness of the photoconductor layer when the rotation of the photoconductor drum 18 is stopped immediately before the filming removal operation is started. It is desirable to move the film thickness detection sensor 60 to the retreat position during the copying operation except during the detection operation so that the drive member 62 moves the film thickness detection sensor 60 to the detection operation position at the time of this detection. .

The surface condition of the photoconductor 18 that serves as a reference for controlling the filming operation is as follows.
The surface potential of can be used. This is detected by the surface potential sensor. FIG. 6 is an explanatory diagram of the mounting position of the surface potential sensor 70. In the illustrated example, the charging device 19 and the black developing device 21B are mounted so as to face the surface of the photoconductor, but the present invention is not limited to this.
It is desirable that the detection of the surface potential by the surface potential sensor 70 be performed during the copy operation immediately before the filming removal operation. That is, the surface potential of a portion where a constant discharge is performed by the charger 19 during such a copying operation is detected. Then, depending on the degree of decrease in the detected potential, the filming removal force in the filming operation is adjusted weaker or the filming operation execution time is adjusted shorter.

Next, the adjustment of the filming removal force will be described. The filming removal force can be adjusted by adjusting the rubbing force of the cleaning agent on the cleaning sleeve 32 against the surface of the photoconductor. This rubbing force can be adjusted by the amount of the cleaning agent conveyed to the cleaning area X by the cleaning sleeve 32, as described above. Specifically, the rotation speed of the cleaning sleeve 32 is adjusted, and the rubbing force can be reduced as the rotation speed is increased. Further, as described above, the amount of the cleaning agent conveyed to the cleaning area X can be adjusted by adjusting the distance between the doctor blade portion 36 and the cleaning sleeve 32. Further, the rubbing force can be adjusted also by adjusting the positions of the magnets P _{1 and the} like forming the main pole 31 in the cleaning sleeve 32. The rubbing force can also be adjusted by adjusting the distance between the cleaning sleeve 32 and the photoconductor 18. The adjustment of the rubbing force is based on the fact that the contact pressure of the cleaning agent in the cleaning region X on the surface of the photoconductor changes.

Next, the adjustment of the filming removal operation time will be described. This is for adjusting the filming removal operation time t shown in FIG. 4, for example, and when the thinning tendency of the photoconductor layer is detected, the filming removal operation time t is adjusted shorter. In addition, for example, when the filming removal operation is set to be executed for each copy of a predetermined number of sheets, the filming removal operation time can be shortened by increasing the interval for performing the filming removal operation. .

For adjustment according to the detection of the film thickness detection sensor 60 and the surface potential sensor 70, the initial film thickness and the initial surface potential are stored as reference values,
It is desirable to compare the detected value after that and this reference value to determine the adjustment amount according to the degree of decrease in film thickness or the degree of decrease in surface potential.

Although the example of using the film thickness detecting sensor and the example of using the surface potential sensor as the detecting means for the surface state of the photosensitive member 18 have been described above, they may be used in combination. Further, regarding the control of the filming removal operation, the example of adjusting the filming removal force and the example of adjusting the execution time of the filming removal operation have been described, but these may be used together. Further, here, the embodiment in which the filming removal operation is performed by the cleaning device has been described. However, instead of or in addition to this, the filming removal is performed by a device dedicated to the filming removal provided with the agent and the agent carrier. Alternatively, the development may be performed with a developing device equipped with an agent and an agent carrier.

[0033]

According to the invention of claim 1, the thickness of the latent image carrying layer is detected by the thickness detecting means, and the agent on the agent carrier is removed by the rubbing force adjusting means according to the output thereof during the filming removal operation. Since the rubbing force for rubbing the latent image bearing member is adjusted by, it is possible to prevent the latent image bearing member layer from being over-cut. According to the invention of claim 2, the thickness of the latent image bearing layer is detected by the thickness detecting means, and the filming removal operation time is adjusted by the operation time adjusting means according to the output thereof. It is possible to prevent excessive shaving. Further, according to the invention of claim 3, the thickness detecting means is moved to a detection operation position where the detection means comes into contact with or comes close to the surface of the latent image carrier, and a withdrawal distance from the surface from the detection operation position. Since the contacting / separating means for moving between the position and the position is provided, the thickness detecting means can be moved to the retracted position during a period in which the thickness detecting is not performed or when cleaning the thickness detecting means. Therefore, it is possible to prevent damage to the thickness detecting means and improve workability such as cleaning. Further, according to the invention of claim 4, in the image forming apparatus of claim 3, the thickness detecting means takes the detection operation position when the surface of the latent image carrier is stopped, and moves the surface of the latent image carrier. Since the contacting / separating unit is configured to take the retracted position during the middle period, dust adhering to the surface of the latent image carrier enters between the surface of the latent image carrier and the detection unit of the detection unit. It is possible to prevent the surface of the latent image carrier and the detector from being damaged. Further, when the thickness detecting means is brought into contact with the surface of the latent image carrier to perform detection, damage due to friction between the detecting portion of the thickness detecting means and the surface of the latent image carrier can be prevented. According to the invention of claim 5, in the image forming apparatus of claim 3, a part of the mounting member to which the thickness detecting means is mounted is brought into contact with the latent image carrier or another position reference part. Since the contacting / separating means is configured to perform the positioning at the detecting operation position, the thickness detecting means can be accurately positioned at the detecting operation position. Therefore, accurate thickness detection can be performed. According to a sixth aspect of the invention, in the image forming apparatus according to the third, fourth or fifth aspect, the thickness detecting means or the mounting member to which the thickness detecting means is attached is elastic at a portion facing the latent image carrier. Since the member is attached, it is possible to prevent the collision due to the contact and separation operation between the surface of the latent image bearing member and the surface of the latent image bearing member of the thickness detecting unit or the mounting member to which the thickness detecting unit is attached facing the latent image bearing member. Therefore, it is possible to prevent damage to the surface of the latent image carrier and the portion of the thickness detecting means and the mounting member to which the thickness detecting means is attached facing the latent image carrier. According to the invention of claim 7, the surface potential of the latent image carrier is detected by the potential detecting means, and the latent image is formed by the agent on the agent carrier during the filming removal operation by the rubbing force adjusting means according to the output. Since the rubbing force for rubbing the carrier is adjusted, it is possible to prevent the latent image carrier layer from being over-cut.
According to the invention of claim 8, the surface potential of the latent image carrier is detected by the potential detecting means, and the filming removal operation time is adjusted by the operation time adjusting means according to the output thereof.
It is possible to prevent excessive scraping of the latent image carrier layer.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a copying machine to which the present invention is applied.

FIG. 2 is an enlarged view of the cleaning device in FIG.

FIG. 3 is a graph showing the relationship between the linear velocity of the cleaning sleeve and the amount of cleaning agent conveyed.

FIG. 4 is a timing chart showing an example of a series of operations including a filming removal operation.

FIG. 5 is an explanatory diagram of a mounting position of a film thickness detection sensor.

FIG. 6 is an explanatory diagram of a mounting position of a surface potential sensor.

[Explanation of symbols]

 18 Photoreceptor Drum 27 Cleaning Device 32 Cleaning Sleeve 31 Main Pole 36 Doctor Blade X Cleaning Area

Claims (8)

[Claims] 1. A latent image carrier on which a latent image carrying layer is formed, and a toner image is formed on the latent image carrying layer during image formation; And a means for changing the rubbing force for rubbing the latent image bearing body with the agent on the agent bearing body, except for the time of image formation. In the image forming apparatus for performing the operation of removing the filming on the latent image carrier by making the rubbing force stronger than that at the time of image formation during the period of time, thickness detecting means for detecting the thickness of the latent image carrying layer, An image forming apparatus comprising: a rubbing force adjusting unit that adjusts the rubbing force during the removing operation according to an output of the thickness detecting unit. 2. A latent image carrier on which a latent image carrying layer is formed, and a toner image is formed on the latent image carrying layer at the time of image formation; And a means for changing the rubbing force for rubbing the latent image bearing body with the agent on the agent bearing body, except for the time of image formation. In the image forming apparatus for performing the operation of removing the filming on the latent image carrier by making the rubbing force stronger than that at the time of image formation during the period of time, thickness detecting means for detecting the thickness of the latent image carrying layer, An image forming apparatus comprising: an operation time adjusting means for adjusting a time for performing the removing operation according to an output of the thickness detecting means. 3. The thickness detecting means is moved between a detecting operation position where the detecting means contacts or approaches the surface of the latent image carrier and a retracted position which is farther from the surface than the detecting operation position. A contacting / separating means for causing the contact / separation is provided.
Alternatively, the image forming apparatus of item 2. 4. The contact / separation means is arranged such that the thickness detecting means takes the detection operation position when the surface of the latent image carrier is stopped and takes the retracted position while the surface of the latent image carrier is moving. The image forming apparatus according to claim 3, further comprising a means. 5. A part of a mounting member to which the thickness detecting means is mounted is brought into contact with the latent image carrier or another position reference part to perform positioning at the detection operation position. The image forming apparatus according to claim 3, wherein the contacting / separating unit is configured. 6. An elastic member is attached to a portion of the thickness detecting means or an attaching member to which the thickness detecting means is attached facing the latent image carrier.
4 or 5 image forming apparatus. 7. A latent image carrier on which a latent image carrying layer is formed on a substrate, and a toner image is formed on the latent image carrying layer at the time of image formation; And a means for changing the rubbing force for rubbing the latent image bearing body with the agent on the agent bearing body, except for the time of image formation. In the image forming apparatus for performing the operation of removing the filming on the latent image carrier by making the rubbing force stronger than that at the time of image formation during the period of time, a potential detecting means for detecting the surface potential of the latent image carrier, An image forming apparatus comprising: a rubbing force adjusting unit that adjusts the rubbing force during the removing operation according to the output of the potential detecting unit. 8. A latent image carrier on which a latent image carrying layer is formed on a substrate, and a toner image is formed on the latent image carrying layer at the time of image formation; And a means for changing the rubbing force for rubbing the latent image bearing body with the agent on the agent bearing body, except for the time of image formation. In the image forming apparatus for performing the operation of removing the filming on the latent image carrier by making the rubbing force stronger than that at the time of image formation during the period of time, a potential detecting means for detecting the surface potential of the latent image carrier, An image forming apparatus comprising: an operation time adjusting means for adjusting a time for performing the removing operation according to an output of the potential detecting means.