JPH04128861A - Cleaning device - Google Patents

Abstract

PURPOSE:To prevent the generation of a cleaning defect and black striae even if continuous copying is executed by rotating an image forming body backward upon completion of a copying operation, then parting a 1st cleaning means from the surface of the image forming body, rotating the image forming body forward and cleaning the surface of the image forming body by a 2nd cleaning means. CONSTITUTION:A photosensitive drum 1 rotates to a copying start position and stops when the copying operation ends. A signal for driving a motor backward is inputted to rotate the drum 1 backward if the number of sheets of continuous copying is >=100 sheets. The toner deposited on the edge of a cleaning blade 6 is parted in this way and transfers to the surface of the drum. A holder 8 is thereafter rotated counterclockwise by de-energizing a solenoid 9 and the blade 6 is moved to the position apart from the peripheral surface of the drum 1 to release the pressurization. The drum 1 is then rotated in a forward direction by controlling the motor and the deposited toner is moved downstream by the blade 6, by which the copying operation is ended.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a cleaning device for an image forming apparatus such as an electrophotographic copying machine.

(Prior Art) Generally, in an image forming apparatus such as an electrophotographic copying machine,
A rotating drum-type image forming body having a photoconductive photosensitive layer on its surface is used, an electrostatic latent image is formed on the photosensitive layer while the image forming body is rotated, and this is developed with a toner. Copying is performed by transferring the toner image onto recording paper. In this image forming apparatus, foreign matter such as toner that was not transferred during transfer and other paper dust remains on the surface of the image forming body after the transfer is completed, and the remaining toner is used to create a new image. Cleaning is performed to prevent overlapping copies from being made. As is well known, this cleaning is performed by disposing a cleaning member such as a blade member or a rotating member on the surface of the image forming body, and removing residual toner on the surface of the image forming body through the sliding action of this cleaning member. be exposed.

(Problem to be Solved by the Invention) In the blade cleaning method using a blade, the edge portion of the blade member is brought into pressure contact with the surface of the image forming body to forcibly remove residual toner from the surface of the image forming body, thereby cleaning the image forming body. will be held.

In an image forming apparatus, an image forming body is repeatedly rotated and stopped according to the copying process every time a copying operation is performed. When the image forming body is repeatedly rotated and stopped, a toner deposit called a toner pool may be accumulated at the tip of the blade that is in contact with the surface of the image forming body. If continuous copying is continued with this toner accumulation as it is, cleaning failure may occur, and streak-like noise, so-called so-called black streaks, may occur on the copied material.

Conventionally, cleaning of the toner pool was performed after copying was completed.
This is done by rotating the image forming body while keeping the blade in contact with the image forming body, but with this method, it is not possible to remove residual toner that has moved from the cleaning blade to the surface of the image forming body. , black lines may still occur when continuous copying is performed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cleaning device that can prevent cleaning defects and black streaks from occurring even when continuous copying is performed.

(Means for Solving the Problems) The present invention has been made to solve the above-mentioned conventional problems, and provides an image forming body capable of forward and reverse rotation for copying, and a surface of this image forming body. a first cleaning means that is movable towards and away from the image forming body and cleans residual toner on the image forming body; and a first cleaning means that is disposed on the upstream side of the image forming body in the moving direction of the image forming body, with respect to the first cleaning means of the image forming body. A first cleaning mode in which the first cleaning means is separated from the surface of the image forming body to perform cleaning after a certain period of time has elapsed since the completion of the copying operation. After the copying operation is completed, the image forming body is reversed, and then the first cleaning means is separated from the surface of the image forming body,
The cleaning apparatus is characterized by comprising a second cleaning mode in which the image forming body is rotated in the normal direction and the surface of the image forming body is cleaned by the second cleaning means.

(Function) After the copying operation is completed, the image forming body is reversed, and then the first cleaning means is separated from the surface of the image forming body, the image forming body is rotated forward, and the surface of the image forming body is cleaned by the second cleaning means. Cleaning removes accumulated toner from the imaging member.

(Example) Examples of the present invention will be described below based on FIGS. 1 to 4.

In FIG. 1, reference numeral 1 indicates a photosensitive drum which is an image forming body, and the photosensitive drum L is rotated in the clockwise direction in the drawing when copying. It rotates to perform copying operations. A cleaning unit 2 is disposed on the photosensitive drum 1 with its open portion lightly abutting the circumferential surface of the drum via a sealing member. The cleaning unit 2 includes a fair brush 3. Bias roller 4 whose part is in contact with the fur brush 3. Brush cleaning means as a second cleaning means consisting of a bias roller blade 5 whose free end is brought into contact with a bias roller 4; a blade cleaning means as a first cleaning means consisting of a cleaning blade 6 and a blade cleaner 7; and a means for transporting removed toner. 12 are provided.

The fur brush 3 is composed of a core metal and conductive brush bristles made of acrylic carbon fibers, and the moving directions are opposite to each other at the contact portion with the photoreceptor drum 1, i.e. It is rotated in the same direction as the photoreceptor drum to scrape off residual toner and the like on the surface of the photoreceptor drum. Bias roller 4 is DCI○
A constant current of μA is applied, and the toner attached to the fur brush 3 is electrostatically attracted. The bias roller blade 5 forcibly scrapes the toner attached to the bias roller 4.
Scrape it off. Almost 99% of the toner on the photoreceptor drum 1
is removed by the brush cleaning means, and the transport means 1
Recovered by 2.

On the other hand, the cleaning blade 6 is made of hard urethane rubber with a thickness of 3 mm and a free edge length of 16.5 mm in the axial direction of the photoreceptor drum, and is fixed to a holder 8 rotatably supported by the cleaning unit 2. has been done. The holder 8 is a shaft 8a provided in the cleaning unit 2.
is rotatably supported. The holder 8 is connected to the actuator of the solenoid 9, and the holder 8 is connected to the actuator of the solenoid 9.
The cleaning blade 6 rotates around the shaft 8a by turning on and off, and selectively moves the cleaning blade 6 between a position where it is in contact with the circumferential surface of the photoreceptor drum 1 and a position where it is retracted.

The blade cleaner 7 is made of a thin plate such as a polyester film, and its base 7a is swingably supported around a shaft 7b provided in the cleaning unit 2, and its free end touches the bottom surface of the cleaning blade 6. The cleaning unit 2 is pressed in the axial direction of the photosensitive drum 1 by a compression spring 13 provided between the base 7a and the cleaning unit 2. When the cleaning blade 6 moves away from the photosensitive drum 1 around the shaft 8a, the blade cleaner 7 is pushed by the spring 13, so the free ends of the cleaning blade 6 and the blade cleaner 7 move relative to each other. Then, the free end of the blade cleaner 7 rubs the edge surface of the cleaning blade 6 to push off toner and foreign matter adhering to the edge of the cleaning blade 6. Reference numeral 1o designates a pre-cleaning charge consisting of a negative bias AC corona charge, and reference numeral 11 designates a polyurethane inlet seal sealing between the unit 2 and the photoreceptor tram 1.

First, a copying process including copying and cleaning steps in a typical electrostatic copying apparatus will be explained.

Normally, in an electrostatic copying device, an electrostatic latent image of a document image is formed on the photosensitive drum by charging, exposing, developing, and transferring devices arranged around the photosensitive drum. A copy is obtained by converting the image into a visible image and transferring the visible image onto recording paper. After the copying operation is completed,
The toner remaining on the surface of the photoreceptor drum is first scraped off with a fur brush 3, and then the remaining toner is further scraped off with a cleaning blade 6 in contact with the surface of the photoreceptor drum 1. The cleaning blade 6 is
Approximately one minute after the end of the copying operation, the solenoid 9 is actuated to rotate the holder 8 counterclockwise around the shaft 8a and move it away from the surface of the photosensitive drum 1. At this time, the edge of the cleaning blade 6 is rubbed by the free end of the blade cleaner 7 as the cleaning blade 6 and the free end of the blade cleaner 7 move relative to each other, and the toner adhering to the edge of the cleaning blade 6 is removed. etc. are scraped off.

The copying/cleaning process in the present invention will be explained.

First, in FIG. 1, it is assumed that the cleaning blade 6 is separated from the photosensitive drum 1.

As shown in FIGS. 3 and 4, when the copy button of the copying machine is turned on, the signal is input to the central processing unit CPU, and based on this, the immediate action circuit that drives the solenoid 9 is driven. Solenoid 9 is energized. Solenoid 9
When the holder 8 is excited, the holder 8 is rotated about the shaft 8a in a direction in which the cleaning blade 6 comes into contact with the photoreceptor drum 1, and the blade 6 comes into contact with the photoreceptor drum 1 as shown in FIG. 2(a). It is in a state where it is in contact with the surface, that is, it is in a pressurized state. Then, similar to the conventional electrostatic copying apparatus, a pre-process is performed in which the photosensitive drum 1 is rotated over a certain period. Next, devices for performing each copying process in the copying apparatus are activated to perform a copying operation. During this copying operation, the number of sheets of copy paper that has been copied is counted by a paper discharge sensor, and the resulting signal is input to the central processing unit 1cPU. When the series of copying operations is completed, the image shown in Fig. 2 (
As shown in a), the photosensitive drum 1 rotates to the copy start position, that is, the home position, and then stops. After the copying operation is completed, it is determined whether the number of copies is 100 or more, and if the number of continuous copies is 100 or more, the motor is driven in reverse by the motor drive circuit that rotationally drives the photosensitive drum. A signal is input. Based on this, the photosensitive drum 1 is reversed as shown in FIG. 2(b).

In this case, the amount of reversal of the photoreceptor drum 1 is 5 m on the circumference of the photoreceptor drum. By reversing the photoreceptor drum, some or all of the toner deposited on the edge of the cleaning blade is pulled away from the edge of the cleaning blade and transferred to the surface of the photoreceptor drum. After that, by releasing the excitation of the solenoid 9, the holder 8 is moved to the shaft 8a.
The cleaning blade 6 is rotated counterclockwise around the center to move the cleaning blade 6 to a position away from the circumferential surface of the photoreceptor drum 1 as shown in FIG. 2(c). That is, the pressure applied to the cleaning blade 6 is released.

The motor is then controlled to:
Move the photoreceptor drum 1 by 20 mm or more in the normal rotation direction of the photoreceptor drum.
Cleaning plate 6 rotates for 25mm to remove accumulated toner.
The copying operation is completed by moving further downstream, and the photosensitive drum 1 enters a standby state, and the photosensitive drum 1 stops. Then, by operating the start button again, the photosensitive drum 1 rotates. The toner that moved with the photoreceptor drum is shown in Figure 2 (
As shown in e), it is scraped off by the 5-fur brush 3 in the pre-process during the copy cycle. The number of consecutive copies is 10
If the number of sheets does not reach 0 or more, one minute after the photoconductor drum stops rotating, control the solenoid 9, etc. to move the cleaning blade 6 to a position away from the circumferential surface of the photoconductor drum 1, and wait. enter the state.

(Effects of the Invention) According to the present invention, after the copying operation is completed, the image forming body is reversed, the pressure contact state of the first cleaning means is released, and then the image forming body is rotated in the normal direction to perform cleaning. Toner attached to the image forming body can be removed, and poor cleaning and black streaks can be prevented even when continuous copying is performed.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a cleaning device according to an embodiment of the present invention, FIG. 2 is a side view showing a cleaning process of the same, and FIG. 3 is a block diagram of the same. FIG. 4 is a flowchart similar to the above. 1... Photosensitive drum, 3... Fur brush, 6...
-Cleaning blade, 7...Plade cleaner. 9...Solenoid. (1 other person)

Claims (1)

[Scope of Claims] 1. An image forming member capable of forward and reverse rotation for copying, and an image forming member that can freely approach and separate from the surface of the image forming member to clean residual toner on the image forming member. In a cleaning device comprising a first cleaning means and a second cleaning means disposed upstream of the first cleaning means of the image forming body in the moving direction of the image forming body, after the copying operation is completed. a first cleaning mode in which cleaning is performed by separating the first cleaning means from the surface of the image forming body after a certain period of time has elapsed; and after completion of the copying operation;
The image forming body is reversely rotated, and then the first cleaning means is separated from the surface of the image forming body, the image forming body is rotated in the normal direction, and the surface of the image forming body is cleaned by the second cleaning means. A cleaning device characterized by having two cleaning modes. 2. The cleaning device according to claim 1, wherein one of the two cleaning modes is automatically selected depending on conditions such as the number of copies. 3. In the second cleaning mode, the image forming body is rotated in reverse while the first cleaning means remains in contact with the image forming body, and then the first cleaning means is separated from the image forming body; 2. A cleaning mode in which the image forming body is rotated in the normal direction and the accumulated toner transferred from the first cleaning means to the image forming body is moved downstream of the first cleaning means. Cleaning device as described.