JP2708816B2 - Method of reducing friction coefficient of cleaning blade - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a cleaning method for cleaning an image forming apparatus such as an electrophotographic copying machine by slidingly contacting the image bearing member after a toner image is transferred. The present invention relates to a method for reducing the coefficient of friction of a blade.

(Prior Art) In an image forming apparatus such as an electrophotographic copying machine, a toner image is formed on a photosensitive drum, and the toner image is transferred to a recording paper to obtain an image. The cleaning device removes toner and the like remaining on the peripheral surface of the photosensitive drum onto which the toner image has been transferred.

A cleaning device for a photoconductor drum usually has a cleaning blade made of an elastic material such as rubber or plastic, and the tip of the cleaning blade is brought into sliding contact with the peripheral surface of the photoconductor drum to thereby form the photoconductor drum. The toner on the peripheral surface is scraped off. Such a cleaning blade, when not in use, has a high coefficient of friction with respect to the photosensitive drum, and by slidingly contacting the photosensitive drum,
The photoconductor drum may be damaged. Further, the cleaning blade itself may be wound by sliding contact with the photosensitive drum.

For this reason, as disclosed in Japanese Patent Application Laid-Open No. 57-111578, an unused cleaning blade attaches toner to the photosensitive drum in advance before the cleaning operation of the photosensitive drum, and cleans the toner. The tip of the blade is slid and the toner is attached to the tip of the cleaning blade. In this manner, if the toner adheres to the tip of the cleaning blade, the coefficient of friction between the tip of the cleaning blade and the peripheral surface of the photosensitive drum is reduced, and thereafter, the cleaning blade does not damage the photosensitive drum without damaging the photosensitive drum. The body drum can be cleaned smoothly.

(Problems to be Solved by the Invention) When toner is to be attached to the tip of the cleaning blade, the image forming apparatus is operated to charge the photosensitive drum, and the developing device attaches the toner to the peripheral surface. ,
The tip of the cleaning blade is brought into sliding contact with the toner on the peripheral surface of the photosensitive drum when the toner adhering portion on the peripheral surface of the photosensitive drum passes through the area facing the cleaning blade.

However, when the toner concentration in the developing device is low, the toner does not sufficiently adhere to the cleaning blade, so that the friction coefficient of the cleaning blade is not reduced, and the photosensitive drum may be damaged or the cleaning blade itself may wind up. There is. Further, when attaching the toner on the photosensitive drum, the carrier may attach to the photosensitive drum together with the toner. If the cleaning blade slidably contacts the carrier adhered to the photosensitive drum, the photosensitive drum and the cleaning blade may be damaged.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to reduce the friction coefficient of a cleaning blade that is in sliding contact with a photoreceptor. It is to provide a reduction method.

(Means for Solving the Problems) The present invention relates to a method of reducing the friction coefficient of a cleaning blade in an image forming apparatus, wherein a toner density in a developing device of the image forming apparatus is reduced before the friction coefficient of the cleaning blade is reduced. Detecting the toner concentration and setting the toner concentration to an appropriate state; and applying a toner to a predetermined area of the photoconductor by a developing device having the toner concentration adjusted to an appropriate state.
Bringing the cleaning blade into sliding contact with the toner-adhered region of the photoreceptor to reduce the friction coefficient of the cleaning blade, thereby achieving the above object.

(Operation) According to the present invention, the friction coefficient of the cleaning blade is reduced after the toner concentration in the developing device is adjusted to an appropriate state, so that the friction coefficient of the cleaning blade is reliably reduced. Therefore, the cleaning blade does not wind up, and the cleaning blade does not damage the photosensitive drum. Further, since the operation of reducing the friction coefficient of the cleaning blade can be performed as needed, the toner is not wasted more than necessary.

(Example) Hereinafter, the present invention will be described with reference to examples.

FIG. 1 is a schematic view of a main part of an image forming apparatus used for carrying out the method of the present invention. In the figure, reference numeral 11 denotes a photosensitive drum rotating in the direction of arrow A. Above the photosensitive drum 11, a charger for uniformly charging the peripheral surface of the photosensitive drum 11 is provided.
12 are arranged. A predetermined image is exposed on the photosensitive drum 11 uniformly charged by the charger 12 to form an electrostatic latent image, and the electrostatic latent image is developed by the developing device on the side of the photosensitive drum 11. At 13 the toner is developed.

The toner in the toner hopper 14 is supplied to the developing device 13 by the rotation of the supply roller 15. The replenished toner is mixed with the carrier in the developing device 13 and charged by friction. A toner density sensor 16 for detecting the toner density in the developing device 13 is provided at an appropriate position of the developing device 13.

The toner image formed on the photosensitive drum 11 by the developing device 13 is transferred by a transfer device 17 to a recording sheet conveyed from a predetermined paper supply unit at a position below the photosensitive drum 11. Then, the recording paper is separated from the photosensitive drum 11 by a separation device 18 provided in parallel with the transfer device 17.

The peripheral surface of the photosensitive drum 11 to which the toner image has been transferred is cleaned by the cleaning device 20. The cleaning device 20 has a cleaning blade 21 made of an elastic material such as rubber, plastic, or the like.
Numeral 21 is selectively located, for example, by a solenoid, at a cleaning position where the tip abuts on the peripheral surface of the photoconductor drum 11 and a retreat position away from the photoconductor drum 11.

FIG. 2 is a block diagram of a control system of the image forming apparatus. In the figure, reference numeral 30 denotes a control unit using, for example, a microcomputer. The control unit 30 receives an output of the toner density sensor 16 provided in the developing device 13.
The output of the control unit 30 is a charger 12 for uniformly charging the photosensitive drum 11, a main motor 31 for driving the photosensitive drum 11,
A developing device 13 for attaching toner to the photosensitive drum 11, a toner replenishing roller 15 driven when replenishing toner from the toner hopper 14 to the developing device 13, and a cleaning device 20
Are provided to solenoids 32 for selectively operating the cleaning blade 21 in the cleaning position and the retreat position.

Next, a control operation by the control unit 30 will be described based on a flowchart of FIG. The control unit 30 is operated immediately before using the image forming apparatus to which the unused cleaning blade 21 is attached, or immediately before resuming use after not using the image forming apparatus for a long period of time.

The control unit 30 first checks whether the toner density in the developing device 13 is appropriate based on the output of the toner density sensor 16 (see FIG. 3, the same applies hereinafter). When the toner concentration in the developing device 13 is appropriate, first, the charger 12 and the main motor 31 are driven to rotate the photosensitive drum 11 in order to reduce the friction coefficient of the cleaning blade 21. Then, the developing device 13 is driven (). As a result, the photoconductor drum 11 is uniformly charged by the charger 12. Then, the charger 12 is stopped after charging the peripheral surface of the photosensitive drum 11 for a predetermined time (and). In the portion charged on the peripheral surface of the photosensitive drum 11,
The developing device 13 causes the toner to adhere. The developing device 13 is stopped after a predetermined time during which the toner can adhere to the charged portion of the photosensitive drum 11 (and). Further, after a predetermined time has elapsed until the toner portion adhering to the photosensitive drum 11 reaches the area facing the cleaning blade 21 of the cleaning device 20, the solenoid 32 is driven (and), and the tip of the cleaning blade 21 is moved. The cleaning position is set. Then, the tip of the cleaning blade 21 is slid on the toner adhered to the peripheral surface of the photosensitive drum 11. As a result, the toner adheres to the tip of the cleaning blade 21. After that, when a predetermined time during which the cleaning blade 21 slides on the toner on the photosensitive drum 11 has elapsed (), the drive of the solenoid 32 is stopped and the drive of the main motor 31 is stopped ().

On the other hand, when the toner density by the toner density sensor 16 provided in the developing device 13 is not in an appropriate state (), the toner replenishing roller 15 is supplied to the developing device 13 to replenish the toner in the toner hopper 14. Is driven ().
At this time, a timer in the control unit 30 is simultaneously started (), and the toner supply roller 15 is driven for a predetermined time. Then, when a predetermined time has elapsed and the timer is up (), the driving of the toner supply roller 15 is stopped (). At this time, since there is no toner in the toner hopper 14, the toner is supplied into the toner hopper 14 ().

If the toner concentration in the developing device 13 becomes appropriate while the toner is being replenished by the toner replenishing roller 15 for a predetermined time (), the driving of the toner replenishing roller 15 is stopped at that point ().

When the toner supply roller 15 has been driven for a predetermined time and then stopped, it is checked again whether the toner density in the developing device 13 is in an appropriate state (). Drive the toner replenishing roller 15 again for a predetermined time until the toner concentration in the developing device 13 becomes an appropriate state.
Is driven.

Then, after the toner concentration in the developing device 13 is in an appropriate state, the above-described operation of reducing the friction coefficient of the cleaning blade 21 is performed.

(Effect of the Invention) According to the method of reducing the friction coefficient of the cleaning blade of the present invention, after the toner concentration in the developing device is adjusted to an appropriate state, the toner is adhered to the photoreceptor by the developing device. Because the cleaning blade is in sliding contact with the toner, there is no possibility that the carrier adheres to the photoconductor,
There is no possibility that the photoconductor or the cleaning blade is damaged.
In addition, since the above-described friction coefficient reducing operation of the cleaning blade can be appropriately performed when necessary, the toner is not wasted more than necessary.

[Brief description of the drawings]

FIG. 1 is a schematic view of a main part of an image forming apparatus used for carrying out the method of the present invention, FIG. 2 is a block diagram of a control system thereof, FIG.
The figure is a flowchart for explaining the operation. 11 photoconductor drum, 12 charger, 13 developing device,
15: toner supply roller, 16: toner concentration sensor, 20
... cleaning device, 21 ... cleaning blade.

Claims (1)

(57) [Claims] 1. A method for reducing a friction coefficient of a cleaning blade in an image forming apparatus, comprising: detecting a toner density in a developing device of the image forming apparatus in advance when reducing the friction coefficient of the cleaning blade; To a proper state, a step of applying toner to a predetermined area of the photoreceptor by a developing device in which the toner concentration is set to an appropriate state, and a cleaning blade slidingly contacting the area of the photoreceptor to which the toner is adhered. Reducing the friction coefficient of the cleaning blade.