JPH0561396A - Image forming device - Google Patents

Abstract

PURPOSE:To prolong the life of a scraper by reducing the friction of a recovery roller and the scraper or making it zero when the quantity of a toner on the recovery roller intruding into the press-contact part of the recovery roller and scraper of a cleaning device is equal to a prescribed quantity or below, or zero. CONSTITUTION:The toner quantity of the surface of the recovery roller intruding into the press-contact part of the recovery roller 21 and scraper 19 of the cleaning device 10 is detected by a detector 70 and an optical sensor 72. When the toner quantity is equal to a fixed value or below, the rotation speed of the recovery roller 21 is changed over to low or zero, or the scraper 19 is retreated by an eccentric cam 64. Thus, the friction of the recovery roller 21 and the scraper 19 can be reduced or made zero.

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 or a printer, and more specifically, a conductive fur brush roller for rubbing the surface of an image carrier, and the conductive fur brush roller. In a cleaning device having a collecting roller that is driven to rotate by being pressed against a brush to remove toner from the brush, and a scraper that presses against the surface of the collecting roller to remove toner from the surface, the life of the scraper is extended. It is about the improvement to do so.

[0002]

2. Description of the Related Art Conventionally, in this type of cleaning apparatus, the toner is removed from the brush of the conductive fur brush by the collecting roller, so that the performance of removing the residual toner from the surface of the image carrier of the conductive fur brush roller is improved. I am maintaining. Then, in order to scrape and remove the toner on the surface of the collecting roller with the scraper, the scraper is brought into pressure contact with the surface of the collecting roller. For this reason, there is a possibility that the cleaning property is deteriorated due to the abrasion of the scraper due to the friction with the surface of the collecting roller and the toner remains.
This problem was particularly remarkable when a metal having a relatively large friction coefficient was used as the material of the collecting roller.

Therefore, it has been proposed that the surface layer of the collecting roller is made of a resin layer to reduce the coefficient of friction with the scraper, thereby extending the life of the scraper (see, for example, Japanese Unexamined Patent Publication No. 2-216175). ).

[0004]

However, even with this configuration, a sufficient amount of toner is not attached to the brush of the conductive fur brush roller, and as a result, the toner enters the pressure contact portion between the surface of the collecting roller and the scraper. If no toner is present on the surface of the collecting roller, the frictional force between the collecting roller surface and the scraper at the pressure contact portion becomes large,
Vibrations of the scraper, chipping of the scraper, winding of the scraper, etc. may occur. Further, since the scraper is constantly in pressure contact with the surface of the collecting roller, the scraper may be worn or deformed, and the cleaning property may be deteriorated. Further, since it is necessary to form the resin surface layer on the collecting roller, the cost is increased accordingly, and it is not suitable for a small-sized and low-cost image forming apparatus.

The present invention has been made in view of the above problems, and an object thereof is to provide an image forming apparatus capable of reliably extending the life of the scraper. Another object of the present invention is to provide an image forming apparatus capable of extending the life of the scraper with a simple structure.

[0006]

In order to achieve the above object, an image forming apparatus according to a first aspect of the present invention is a conductive fur brush roller for rubbing the surface of an image carrier, and a brush of the conductive fur brush roller. In an image forming apparatus including a cleaning device having a collecting roller that is pressed against and rotationally driven to remove toner from the brush, and a scraper that is pressed against the surface of the collecting roller to remove toner from the surface, Toner detection means for detecting the amount of toner adhering to the collection roller, and drive switching means for switching the rotation drive state of the collection roller based on the output of the toner detection means are provided. In addition, claim 2
In the image forming apparatus, a conductive fur brush roller that rubs the surface of the image carrier, a collection roller that is driven to rotate by being pressed against the brush of the conductive fur brush roller, and removes toner from the brush, In an image forming apparatus provided with a cleaning device having a scraper that presses against the surface of a roller and removes toner from the surface, the rotation driving state of the collecting roller is changed while waiting for an image formation start command. A drive switching means for switching to a state different from the rotational drive state during the image forming operation is provided. According to another aspect of the image forming apparatus of the present invention, a conductive fur brush roller that rubs the surface of the image carrier and a brush of the conductive fur brush roller are pressed to rotate and driven to remove toner from the brush. An image forming apparatus including a cleaning device having a roller and a scraper that presses against the surface of the collecting roller to remove toner from the surface, and a plurality of developing devices are arranged to face the image carrier. In the above, when all of the plurality of developing devices are inactive for a certain period of time or more, the rotation driving state of the recovery roller is defined as the rotation driving state when at least one of the plurality of developing devices is operating. Is provided with drive switching means for switching between different states. The image forming apparatus according to claim 4 is
2. The image forming apparatus according to claim 1, further comprising, instead of or in addition to the drive switching means, a separating means for separating the scraper from the surface of the collecting roller based on the output of the toner detecting means. To do. Further, in the image forming apparatus according to claim 2, in the image forming apparatus according to claim 2, the scraper is replaced with the scraper while waiting for an image formation start command in addition to or in addition to the drive switching means. It is characterized in that a separating means for separating from the surface of the collecting roller is provided.
An image forming apparatus according to a sixth aspect of the present invention is the image forming apparatus according to the second aspect, in which, in place of or in addition to the drive switching unit, all of the plurality of developing devices are inactive for a predetermined time or more. A separating means for separating the scraper from the surface of the collecting roller is provided. The image forming apparatus according to claim 7 is the image forming apparatus according to claim 4, 5 or 6, wherein the separating means separates the scraper from the surface of the collecting roller before starting the separation. Alternatively, a collecting roller reversing unit for reversing the collecting roller by a predetermined amount is provided while the scraper is separated from the surface of the collecting roller by the separating unit. The image forming apparatus according to claim 8 is the image forming apparatus according to claim 1,
In the image forming apparatus of 2, 3, 4, 5 or 6, the temperature detecting means for detecting the temperature of the scraper and the heater driven by the output of the temperature detecting means to heat the scraper are provided. It is characterized by.

[0007]

According to the present invention, the toner detecting means detects whether or not sufficient toner is present on the surface of the collecting roller that enters the pressure contact portion between the collecting roller and the scraper. , If there is not enough toner,
The drive switching means switches the rotation driving state of the collecting roller, or the separating means separates the scraper from the surface of the collecting roller, whereby the frictional force between the collecting roller and the scraper is reduced (including zero). Is.
In the image forming apparatus according to claim 2 or 5, when waiting for the image formation start command and waiting, the drive switching means sets the rotation driving state of the collecting roller to a state different from the rotation driving state during the image forming operation. The scraper is separated from the surface of the collecting roller by switching or the separating means, whereby the amount of toner on the surface of the collecting roller that enters the pressure contact portion between the collecting roller and the scraper decreases, and abrasion of the scraper occurs. Is to prevent. The image forming apparatus according to claim 3 or 6, wherein all of the plurality of developing devices are inactive for a predetermined time or more, and as a result, no toner is input to the conductive fur brush of the cleaning device, the drive switching means. And the rotation driving state of the collecting roller is switched to a state different from the rotation driving state when at least one of the plurality of developing devices is in the operating state, or the scraper is separated from the surface of the collecting roller by the separating means, whereby the collecting roller is collected. This prevents the amount of toner on the surface of the recovery roller that enters the pressure contact portion between the roller and the scraper, and the abrasion of the scraper. An image forming apparatus according to claim 7, wherein the collecting roller reversing means causes the separating means to separate the scraper from the surface of the collecting roller before the separation starts, or the separating means collects the scraper. During the period when the scraper is separated from the surface of the scraper, the recovery roller is reversed by a predetermined amount, so that the tip of the scraper is re-press-contacted with the scraper. It is something that should not be pressed onto. In the image forming apparatus according to the eighth aspect, the temperature of the scraper is detected by the temperature detecting means, and the heater is driven based on the output of the temperature detecting means to maintain the scraper at a predetermined temperature.

[0008]

EXAMPLE An example in which the present invention is applied to a cleaning device in a color electrophotographic printer will be described.
First, an outline of the entire printer will be described with reference to FIG. 3 showing an overall schematic configuration. The surface of a drum-shaped photoconductor (hereinafter referred to as a photoconductor drum) 14, which is a latent image carrier that is rotated counterclockwise, is charged by a charger 11 and then black (BL) by an optical writing device 12. Scanning exposure of the image signal of (1) to form a negative latent image (a state in which the image area is exposed and the surface potential of the photoconductor is attenuated). The latent image is developed by the black developing device BL (using black toner) of the developing device 13 to form a black toner image on the photoconductor drum 14. At this time, the developing devices Y, M, and C (each of which uses yellow, magenta, and cyan toners) other than the black developing device BL in the developing device 13 do not supply toner to the latent image on the photosensitive drum 14 and are inoperative. Controlled by the state. In order to make such an inoperative state, in this example, the developing device moving mechanism 13a using an eccentric roller is used.
Is provided so that the developing device to be inactivated is retracted from the surface of the photoconductor drum 14. After the toner image is formed, the charge / PCC charger 9 charges the photoconductor drum 14 to charge the black (BL) latent image on the photoconductor drum 14. At this time, the cleaning device 10 is shown in FIG.
As shown in (a), the photosensitive drum 14 is separated and inoperative. The cleaning device 10 will be described in detail later. Next, by the same method as the method of forming the black (BL) toner image, the processes of charging, exposing, developing, and discharging are repeated, and Y, M, and C (yellow, magenta, and cyan) on the photoconductor drum 14. Toner images are sequentially superposed and formed. The transfer paper 2 conveyed by the paper feed roller 3 and the registration roller 4 after all the toner development is completed.
Then, the transfer charger 5 electrostatically transfers the toner image. The toner image transferred onto the transfer paper 2 is fixed by heating the fixing roller 6, and then discharged onto the paper discharge tray 8 by the paper discharge roller 7. On the other hand, after the electrostatic transfer, the toner image remaining on the photoconductor drum 14 is removed by the cleaning device 10 which is moved to be in pressure contact with the photoconductor drum 14 and is in an operating state, as shown in FIG. 2B. Then, one cycle of color image formation is completed.

Next, the cleaning device 10 will be described in detail with reference to FIGS. 1 (a) and 1 (b). FIG. 1A is a front view showing a schematic configuration inside a casing 20 of the cleaning device 10, and FIG. 1B is a perspective view showing a schematic configuration of a support mechanism of a scraper 19 of the cleaning device 10.
In FIG. 1A, in a casing 20 of the cleaning device 10, a conductive fur brush roller 24 for rubbing the peripheral surface of the photosensitive drum 14 for cleaning is provided, and a brush portion of the conductive fur brush roller 24. Collecting roller 21 for cutting into the toner to remove the toner, and the collecting roller 2
A scraper 19 for scraping off the toner from one circumferential surface, and a coil spring 22 for discharging the toner scraped off from the collecting roller 21 by the scraper to the outside of the casing 20 are provided. Sealing members 30 for preventing toner scattering are provided at both edges of the lower opening of the casing 20. Here, the conductive fur brush roller 24 is formed by implanting conductive fibers (for example, “Toray's product name SA-7, etc.”) on the peripheral surface of the stainless steel or aluminum roller 24a, and the power supply 50 reverses the toner. The collecting roller 21 is a metallic roller, and has a power source 51 having a polarity opposite to that of the toner and the power source 50.
A larger bias is applied. The biting amount of the collecting roller 21 with respect to the brush portion of the conductive fur brush roller 24 is set to about 1 to 2 mm. And
The conductive fur brush roller 24 and the collecting roller 21 rotate in the same direction as indicated by the arrow, and the coil spring 22 rotates in a predetermined direction. For this purpose, a shaft (not shown) rotatably supported by the casing 20 of each of the conductive fur brush roller 24 and the collecting roller 21 and a rotary shaft 23 to which the coil spring 22 is fixed are connected by a gear (not shown). The driving force from the motor 52 is input to the rotary shaft 23 of these. Instead, the conductive fur brush roller 2
4, the collection roller 21 and the coil spring 22 may be drive-controlled independently of each other. The rotating shaft 23 penetrates the casing 20 and is rotatably supported by the side plate of the apparatus, and also serves as a swing center for swinging the casing, which will be described later.

Above the casing 20 of the cleaning device 10, the conductive fur brush roller 24 is in an operating position where it bites into the peripheral surface of the photosensitive drum 14 by a predetermined amount, and the conductive fur brush roller 24 surrounds the photosensitive drum 14. A swinging mechanism for swinging the entire casing around the support shaft 23 is provided so that an inoperative position separated from the surface can be obtained. The swinging mechanism includes a tension spring 51 that applies a turning force to the casing 20 in the clockwise direction around the support shaft 23, an eccentric roller 16 attached to the drive shaft 17, and a free end on the peripheral surface of the eccentric roller 16. Pressure contact,
A leaf spring 18 whose base end is fixed to the upper surface of the casing 20.
It consists of and. Then, the shaft 17 of the eccentric roller 16 is rotationally driven by the motor 52. This casing 2
The swing of 0 will be described. First, during a period in which a color image is formed on the photoconductor drum 14 in an overlapping manner, the conductive fur brush roller 24 moves around the photoconductor drum 14 as shown in FIG. The rotation position of the eccentric roller 16 is set to a position where the displacement amount is minimized so as to take an inoperative position separated from the surface. Then, after the toner on the photoconductor drum 14 is transferred to the transfer paper 2, the eccentric roller 16 is moved around the rotation shaft 17 by 1
Rotate 80 °. Then, the casing 20 rotates counterclockwise in the figure about the rotation shaft 23 against the force of the tension spring 51, and the conductive fur brush roller 24 causes the photosensitive drum 14 to rotate, as shown in FIG. 2B. It comes into contact with a predetermined amount of bite to rub against its peripheral surface. The amount of this bite is determined by the outer diameter of an abutting roller for gap maintenance (not shown) which is attached to both end shafts of the conductive fur brush roller 24 and whose peripheral surface abuts on the photosensitive drum 14, and is 0.5 ~ 2mm is desirable. The leaf spring 18 serves to press the abutting roller against the photosensitive drum 14. After cleaning, add 1 more eccentric roller 16.
The casing 20 rotates by 80 ° and the tension spring 5
The force of 1 rotates clockwise about the rotary shaft 23, and the conductive fur brush roller 24 is moved to the inoperative position where it is separated from the photosensitive drum 14. The movement to the inoperative position after the cleaning is completed until the toner image of the first color in the subsequent copying operation in which the toner images are superposed on the photosensitive drum 14 reaches the position facing the cleaning device 10. To do. For example, it is performed immediately after the cleaning is completed.

In the above arrangement, the cleaning device 10 located at the operating position removes the residual toner on the photosensitive drum 14 as follows. The toner remaining on the photoconductor drum 14 after transfer is first removed from the photoconductor drum 14 by the conductive fur brush roller 24 to which a bias having a polarity opposite to that of the toner is applied by the power supply 50, and electrostatically applied to the brush. Adhere to. The toner attached to the brush is electrostatically transferred to the side of the collecting roller 21 to which a bias larger than that of the conductive fur brush roller 24 is applied by the power source 53 at the contact portion with the collecting roller 21, and the scraper 19 collects the toner. Removed from the surface. The toner scraped off the collecting roller 21 by the scraper is discharged to the outside of the casing 20 by the coil spring 22.

In the state where the recovery roller 21 is rotated while the scraper 19 is in pressure contact,
If no toner is present on the surface of the recovery roller 21 that has entered the pressure contact portion between the recovery roller 21 and the scraper 19, the frictional force between the surface of the recovery roller 21 and the scraper 19 at the pressure contact portion increases, and the scraper 19 Problems such as vibration, chipping, and entrapment may occur. Therefore, in the present embodiment, when there is not enough toner on the surface of the collecting roller that enters the pressure contact portion between the collecting roller 21 and the scraper 19, the friction between the collecting roller 21 and the scraper 19 is eliminated, or , To reduce.

First, the determination as to whether or not the toner is sufficiently present on the surface of the collecting roller that enters the pressure contact portion between the collecting roller 21 and the scraper 19 will be described. Whether there is sufficient toner on the surface of the collecting roller that enters the pressure contact portion between the collecting roller 21 and the scraper 19 depends on the amount of residual toner on the photosensitive drum 14 after transfer, the photosensitive drum 14 and the like.
Input toner amount from the surface to the conductive fur brush roller 24, the conductive fur brush roller 24 to the collecting roller 21
It is possible to make a determination by detecting any of the amount of toner transferred to the contact roller, the amount of toner on the surface of the recovery roller 21 moving from the pressure contact portion with the conductive fur brush roller 24 to the pressure contact portion with the scraper 19, and the like. .. Further, in the sequence control, the time when the input toner from the surface of the photoconductor drum 14 to the conductive fur brush roller 24 does not exist is a fixed time (for example, the time when the photoconductor drum 14 rotates 2 to 3 times).
In the above case, for example, when all the developing devices 13 are inactive for a certain period of time, it can be determined that the toner on the surface of the collecting roller entering the pressure contact portion is insufficient. Further, when the apparatus waits for the print start command and there is no toner to be input to the conductive fur brush roller 24, the scraper 1 at this time
If the recovery roller 21 continues to rotate in a state in which 9 is in pressure contact, the amount of toner on the surface of the recovery roller that enters the pressure contact portion runs short, so similarly, the recovery roller 21 and the scraper 1
It is desirable to eliminate or reduce the friction with 9.

To detect the amount of residual toner on the photosensitive drum 14 after transfer and the amount of toner on the surface of the recovery roller 21 moving from the pressure contact portion with the conductive fur brush roller 24 to the pressure contact portion with the scraper 19. For example, a reflection type optical sensor can be used. Reference numeral 7 in FIG.
2 is a recovery roller 21 moving from a pressure contact portion with the conductive fur brush roller 24 to a pressure contact portion with the scraper 19.
2 illustrates a reflective optical sensor that detects the amount of toner on the surface. In order to detect the amount of toner input from the surface of the photosensitive drum 14 to the conductive fur brush roller 24 and the amount of toner transferred from the conductive fur brush roller 24 to the collecting roller 21, for example, such toner movement is used. The electric current or the resistance value between them (which varies depending on the presence or absence of toner) is detected. For example, as shown in FIG. 1A, a detector 70 for detecting a current due to toner movement is provided in a bias applying path from the power source 50 to the conductive fur brush roller 24 so that the surface of the photosensitive drum 14 is electrically conductive. The amount of toner input to the fur brush roller 24 can be detected. When the power source 50 is a constant voltage type, the detector 70 detects when a predetermined current value is detected,
However, in the case of a constant current type, when a predetermined potential is detected,
The detection signal is output to the control unit 73. Instead of this, a plurality of signals corresponding to the toner movement amount may be output to the control unit 73. A similar detector is provided in the bias applying path from the power source 53 to the collecting roller 21, and the amount of toner transferred from the conductive fur brush roller 24 to the collecting roller 21 can be detected. Here, the cleaning device 10
Even in the inactive position, the amount of toner transferred from the conductive fur brush roller 24 to the collecting roller 21 is detected by the current flowing through the circuit of the power source 50, the conductive fur brush roller, the collecting roller 21, and the power source 53. In this case, the reference for discriminating the amount of moving toner and the like is switched between when the cleaning device 10 is in the operating position and when it is in the non-operating position.

Next, a structure for eliminating or reducing the friction between the collecting roller 21 and the scraper 19 will be described. The rotation speed of the collecting roller 21 and the collecting roller 21
By changing the pressure contact force between the scraper 19 and the scraper 19, it is possible to eliminate or reduce the friction between the collecting roller 21 and the scraper 19. Specifically, the rotation speed and the pressure contact force may be switched in multiple stages according to the amount of toner on the surface of the recovery roller that enters the pressure contact portion between the recovery roller 21 and the scraper 19. When the toner amount is equal to or less than the predetermined amount, the rotation speed and / or the upper pressing force may be set to zero. Collection roller 21
In order to switch the rotation speed of the collecting roller 21, the rotation speed of the motor 52, which is the drive source of the collecting roller 21, is controlled by the control unit 73.
Control with.

In order to switch the pressure contact force between the collecting roller 21 and the scraper 19, the following structure is adopted in this example. That is, in FIG. 1B, the scraper holder 19a to which the scraper 19 is attached is swingably attached to the case 20 by the support shaft 60. A pin 61a, which is planted in a lever 61 fixed to one end of the support shaft 60, locks one end of a spring 63 which gives a turning force in a direction in which the tip end of the scraper 19 moves to the collecting roller 21 side.
The other end of the spring 63 is attached to the side wall 62 of the casing 20.
It is locked to the pin 62a fixed to. On the spring 63 side of the lever 61, an eccentric cam 64 fixed to a rotary shaft 64a driven by a drive source (not shown) is provided so as to abut the lever 61. The rotation position of the eccentric cam 64 is switched by the control of the rotation shaft 64a by the control unit 73, and the pressure contact force between the scraper 19 and the recovery roller 21 is switched.

Incidentally, for example, the collecting roller 21 and the scraper 1
When the amount of toner on the surface of the collecting roller entering the pressure contact portion with the collecting roller 9 is less than a predetermined amount, the scraper 19 causes the collecting roller 2 to move.
When the pressure contact force is set to 0 by separating the scraper 19 from the surface of 1, the collecting roller 21 is set immediately before the scraper 19 is separated.
By a certain amount, or the collecting roller 2
When the scraper 19 is re-press-contacted with the scraper 19, the scraper 19 is removed from the surface of the recovery roller 21 that has been cleaned by the scraper 19 before separation.
It is desirable that the tip end of each of them should be in pressure contact. This is for the following reason. That is, on the surface of the recovery roller 21 with which the leading edge of the scraper 19 is in pressure contact at the start of separation, a pool of toner and paper dust blocked by the leading edge is formed. When the rotation of the collecting roller 21 is stopped at the same time when the separation is started and the scraper 19 is re-pressed as it is,
The tip edge of the scraper 19 may come into pressure contact with the pool, and at least a part of the toner and paper dust in the pool may be transferred to the surface of the collecting roller 21 further downstream than the tip edge of the scraper 19 in the rotation direction of the collecting roller 21. is there. The toner or the like transferred in this way is not scraped off by the scraper 19 and is reattached to the conductive fur brush roller 24 by the rotation of the collecting roller 21 as it is.
Then, it re-adheres on the photosensitive drum 14 and causes a defect such as uneven image density due to uneven charging. In order to prevent such a problem, the scraper 1 is operated as described above.
When the 9 is re-pressed, the tip of the scraper 19 is pressed to the surface of the recovery roller 21 that has been cleaned by the scraper 19 before being separated.

When the scraper 19 is formed of a material which is deteriorated by a temperature change, particularly a material which is liable to be chipped at the tip edge portion at a low temperature, the temperature of the scraper 19 is set to a predetermined temperature. Is desirable. For that purpose, a heater 21a is arranged in the vicinity of the scraper 19, for example, in the recovery roller 21, and a temperature sensor 71 for detecting the temperature of the scraper 19 is attached to, for example, the holder 19a, and a predetermined value is determined based on the output of the temperature sensor 71. When the temperature falls below the temperature, the heater 21a is driven.

[0019]

According to the image forming apparatus of the present invention, the toner detecting means determines whether or not sufficient toner is present on the surface of the collecting roller entering the pressure contact portion between the collecting roller and the scraper. If sufficient toner is not detected, the rotation switching state of the collecting roller is switched by the drive switching unit, or the scraper is separated from the surface of the collecting roller by the separating unit, whereby the collecting roller and the scraper are separated from each other. Since it reduces the frictional force (including setting it to 0),
It is possible to prevent abrasion of the scraper, etc., and reliably extend the life of the scraper. In the image forming apparatus according to claim 2 or 5, when waiting for the image formation start command and waiting, the drive switching means sets the rotation driving state of the collecting roller to a state different from the rotation driving state during the image forming operation. The scraper is separated from the surface of the collecting roller by switching or the separating means, whereby the amount of toner on the surface of the collecting roller that enters the pressure contact portion between the collecting roller and the scraper decreases, and abrasion of the scraper occurs. Since the above is prevented, the scraper can surely have a long service life with a simple configuration by sequence control. The image forming apparatus according to claim 3 or 6,
All of the plurality of developing devices are inactive for a certain time or more,
As a result, when the toner is not input to the conductive fur brush of the cleaning device, the drive switching means sets the rotation driving state of the collecting roller to at least one of the plurality of developing devices.
One is switched to a state different from the rotational drive state when the other is in the operating state, or the scraper is separated from the surface of the recovery roller by the separating means, whereby the surface of the recovery roller enters the pressure contact portion between the recovery roller and the scraper. It is possible to prevent abrasion of the scraper due to a decrease in the amount of the upper toner, so that it is possible to reliably extend the life of the scraper. An image forming apparatus according to claim 7, wherein the collecting roller reversing means causes the separating means to separate the scraper from the surface of the collecting roller before the separation starts, or the separating means collects the scraper. During the period when the scraper is separated from the surface of the scraper, the recovery roller is reversed by a predetermined amount, so that the tip of the scraper is re-press-contacted with the scraper. Since it is not pressed against the top of the scraper, when the scraper is re-contacted, the tip of the scraper presses against the pool of toner and paper powder, and part of the toner in this pool rotates as the conductive roller brushes. Further, it is possible to prevent re-adhesion to the image carrier to cause unevenness in image density. The image forming apparatus according to claim 8, wherein the temperature detecting means detects the temperature of the scraper, and the heater is driven based on the output of the temperature detecting means to maintain the scraper at a predetermined temperature. Even when the scraper is formed with, the scraper can be prevented from being chipped.

[Brief description of drawings]

FIG. 1A is a front view showing a schematic configuration of a cleaning device according to an embodiment, and FIG. 1B is a perspective view showing a schematic configuration of a scraper support mechanism of the cleaning device.

2A is a front view of the cleaning device in an inoperative position, and FIG. 2B is a front view of the cleaning device in an operating position.

FIG. 3 is a front view showing a schematic configuration of a color electrophotographic printer using the cleaning device.

[Explanation of symbols]

10 Cleaning Device, 13 Developing Device (4 Colors) 14 Photosensitive Drum, 16 Eccentric Roller 17 Rotating Shaft, 18 Leaf Spring 19 Scraper, 19a Holder 20 Casing, 21 Recovery Roller 21a Heater, 22 Coil Spring 23 Rotating Shaft, 24 Conductivity Fur brush roller 50 power supply, 51 spring 52 motor, 53 power supply 60 support shaft, 61 lever 62 casing side plate, 63 spring 64 eccentric cam, 70 detector 71 temperature sensor, 73 control unit

Claims (8)

[Claims] 1. A conductive fur brush roller for rubbing the surface of an image bearing member, a collection roller for pressing and rotating the brush of the conductive fur brush roller to remove toner from the brush, and the collection roller. In an image forming apparatus equipped with a cleaning device having a scraper that presses against the surface of the toner and removes the toner from the surface, a toner detecting means for detecting the amount of toner adhering to the collecting roller and an output of the toner detecting means. An image forming apparatus comprising: a drive switching unit that switches a rotation drive state of the collecting roller based on the drive roller. 2. A conductive fur brush roller that rubs the surface of the image carrier, a collection roller that is driven to rotate by being pressed against the brush of the conductive fur brush roller, and removes toner from the brush, and the collection roller. In an image forming apparatus provided with a cleaning device having a scraper that presses against the surface of and removes toner from the surface, the rotation driving state of the collecting roller is changed while waiting for an image formation start command. An image forming apparatus comprising drive switching means for switching to a state different from the rotational drive state during an image forming operation. 3. A conductive fur brush roller that rubs the surface of the image carrier, a collecting roller that is driven to rotate by being pressed against the brush of the conductive fur brush roller, and removes toner from the brush, and the collecting roller. An image forming apparatus including a cleaning device having a scraper that presses against the surface of the sheet and removes the toner from the surface, and a plurality of developing devices arranged to face the image carrier. Driving for switching the rotation driving state of the collecting roller to a state different from the rotation driving state when at least one of the plurality of developing devices is in the operating state when all of the apparatuses are inactive for a certain time or more. An image forming apparatus comprising a switching unit. 4. A separation means for separating the scraper from the surface of the collection roller based on the output of the toner detection means is provided in place of or in addition to the drive switching means. Image forming device. 5. In place of or in addition to the drive switching means, while waiting for an image formation start command,
The image forming apparatus according to claim 2, further comprising a separating unit that separates the scraper from the surface of the collecting roller. 6. In place of or in addition to the drive switching means, a separating means for separating the scraper from the surface of the collecting roller when all of the plurality of developing devices are inoperative for a predetermined time or longer. The image forming apparatus according to claim 3, wherein the image forming apparatus is provided. 7. The separating means separates the scraper from the surface of the collecting roller before the separation is started, or the separating means separates the scraper from the surface of the collecting roller. 7. The image forming apparatus according to claim 4, 5 or 6, further comprising recovery roller reversing means for reversing the recovery roller by a predetermined amount during a certain period. 8. A temperature detecting means for detecting the temperature of the scraper, and a heater which is driven based on the output of the temperature detecting means to heat the scraper. 3, 4, 5 or 6 image forming apparatus.