JPS6195381A - Method for controlling cleaning device - Google Patents

Abstract

PURPOSE:To maintain a stable cleaning function over along period of time by sticking a toner to the surface of an image carrying body before the start of the next image forming operation only when the next image forming operation fails to be carried out within the prescribed time after the end of one image forming operation. CONSTITUTION:The toner sticking to the edge of a cleaning blade 8a is used as it is as a lubricating agent for the blade 8a in the starting stage of the next operation without detaching the blade 8a from the image carrying body 1 when the time since the end of one copying operation till the start of the next operation is short. A slight amt. of the toner is supplied to the side of the body 1 to stick the toner to the cleaned blade edge prior to the start of the operation in the stage of executing the image forming operation upon lapse of the specified time after the previous copying operation. The blade edge is thus made to provide the stable cleaning function without generating the incident of an insufficient lubricating effect owing to the lack of the toner.

Description

Detailed Description of the Invention (1) Purpose of the Invention (Field of Industrial Application) The present invention relates to an image forming apparatus using an electrostatic transfer process such as an electrophotographic copying machine or a printer, and in particular to a method of controlling a cleaning device thereof. (Prior art and problems to be solved) In an image forming apparatus that repeats the process of forming a transferable toner image on the surface of an image carrier and transferring this toner image to a transfer material, during transfer, the transfer material It is essential to clean the residual toner that remains on the surface of the image carrier without being transferred to the surface of the image carrier to obtain a good quality image. It is widely used because it has an excellent cleaning function, is compact and has a simple configuration, and is designed to scrape off residual toner by being brought into pressure contact with the body surface.

However, if this type of cleaning plate is kept in pressure contact with the surface of the image carrier for a long period of time, toner, paper particles, etc. will gradually accumulate and solidify on the edge portion that is in pressure contact with the surface, causing the image to spread over the entire length of the edge. This results in uneven pressure contact with the surface of the image carrier, leading to a risk of poor cleaning or damage to the surface of the image carrier.

In order to avoid such drawbacks, a method has already been proposed in which the blade is retracted from the image carrier when not in use, and the blade edge is cleaned during the retraction movement. The cleaning device used by Blade Edge generally comes into contact with the moving image bearing surface in a direction that impedes its movement in order to obtain a good toner scraping effect. Although it is undesirable for a large amount of toner to adhere to the image carrier, it has been found that it is desirable for a small amount of toner to always exist between the blade and the image carrier so that the toner acts as a lubricant. ing.

However, when cleaning the blade edge as described above, if the original to be copied has a lot of white background, that is, if the document to be copied has a small amount of toner and is continuously copied, the amount of toner at the blade edge may be insufficient. As a result, the friction between the blade and the image carrier increases, which may cause the blade to turn over, resulting in poor cleaning.

The present invention has been made to deal with such a situation, and it is an object of the present invention to provide a method of controlling a cleaning device that can maintain a stable cleaning function over a long period of time. be.

(2) Structure of the Invention In order to achieve the above object, the present invention provides a cleaning device equipped with a cleaning plate that can freely approach and separate from the image carrier and cleans the edges when separated from the image carrier. , the timer is activated after the copying operation is completed or after the warm-up rotation is completed after the power switch is turned on, and the cleaning plate is not pressed against the surface of the image carrier until the timer counts up. After loading, a small amount of toner is supplied to the surface of the image carrier before starting the next copying operation.
) 7” v-)°”″′ Lubrication 1li13.!=+?+
7))−+, i.

In any case, toner is present as a lubricant on the blade edge and a stable cleaning action can be achieved, and if further copying is to be performed after a relatively short period of time determined by a timer. for,
There is a method that can improve the working efficiency of the apparatus by omitting the operation for adhering toner to the image carrier and allowing the actual copying work to begin immediately.

(Description of Examples).

No. 2 is an explanatory diagram of the main parts of a copying machine to which the present invention is applied, in which a photoconductive layer on the surface of a photoreceptor 10 formed in a rotating cylindrical shape and rotating in the direction of arrow A is charged by a charger 2. After being uniformly charged, a light image corresponding to a document (not shown) is applied to the charged surface from the direction of arrow 9 to form an electrostatic latent image, and as the photoreceptor rotates, the latent image is transferred from the developing device. Developed by supplied toner.

This developed toner image, together with a transfer material (not shown) supplied through a conveyance path 4, reaches a transfer section having a transfer charger 5, where the toner is transferred to the transfer material, and is then transferred to a separation roller 6.
It is separated from the photoreceptor by a, and passes through a conveyance path 6b to proceed to the next process such as a fixing site.

On the other hand, residual toner that does not contribute to the transfer and remains on the surface of the photoreceptor at the transfer site has its charge neutralized by the neutralizing charger, and further reaches the cleaning device 8 where it is scraped off by the cleaning plate 8a.

The symbol Qs in the figure is, for example, UCOM87A manufactured by NEC Corporation.
A one-chip microcomputer such as D, Q2 is a high voltage unit. It is assumed that a predetermined voltage is applied to each charger 2, 5, 7, etc. to the high voltage unit. Also, the developing bias applied to the developing device has a DC component of 0 to 5.
00v1 AC component power 1000v11500 Hz, D
This is to change the image density by changing the C component.

For the DC component, the microcomputer Q1 converts a specific pulse into an integrator circuit Q.
3, the integrator circuit Q3 outputs an analog value of 10V to 15V to the high voltage unit Q2 according to the pulse, and the high voltage unit Q2 responds to the analog value of 0 to 50V.
A developing bias is applied by outputting a 0 V DC component and superimposing the AD acid component.

Loads required for other control systems are connected to other ports of the microcomputer Ql, but they are not related to the present invention and will therefore be omitted.

FIG. 3 is an enlarged side view of the IJ = ing device shown at 8 in FIG.

The cleaning device 8 includes a casing 8C disposed close to and parallel to the axis of the cylindrical photoreceptor 1, and includes a cleaning plate 8a. The cleaning plate 8a has one end attached to the support member 8b,
The other edge faces the photoreceptor.

The support member 8b is rotatably supported by the lever 9 by a shaft 8d, so that the edge of the blade is uniformly pressed against the surface of the photoreceptor 1 over its entire length.

Since the lever 9 is biased downward in the drawing by the spring 11, the edge of the cleaning blade is pressed against the photoreceptor with a predetermined pressure, and the pressure can be adjusted by the position of the locking part 12. The residual toner on the body surface is removed by cleaning plate 8a.
The scraped toner is guided to the scooping sheet 13 and reaches the storage section in the casing, and is further conveyed perpendicularly to the plane of the paper by the screw conveyor 14 as necessary to the casing. is discharged outside.

When the copying operation is completed, as is well known, the solenoid 10 is energized by a copying end signal.
The lever 9t rotates in the clockwise direction shown in the figure, and the edge of the cleaning plate 8& rotates in the direction of arrow B, separating it from the surface of the photoconductor, and at the same time, contacts the cleaning member 15 disposed inside the casing to remove the blade edge. The toner adhering to the surface is removed.

Next, a method of controlling the cleaning device of the present invention will be explained with reference to flowcharts shown in FIGS. 1A and 1B.

The photoreceptor l of the cleaning device has a diameter of 60 m and a rate of 1 B seconds.
It shall rotate. When the copying operation is completed, or when the current switch is closed and the warm-up rotation of the photoreceptor is completed (Ss), a timer built into the microcomputer Qs, for example, a 10-minute timer, starts operating (S2).

At this time, the edge of the cleaning plate is maintained in pressure contact with the photoreceptor 1. Note that the above-mentioned timer is not limited to a 10-minute timer, and the cleaning plate is maintained in pressure contact with the photoreceptor 1. can also be set at an appropriate time within a range that does not leave any blade marks on the photoreceptor during the next copying operation.

The timer is an internal timer of Ql, and when it counts up, it performs internal interrupt processing, and the cleaning device 8
The solenoid 10 is energized to separate the blade 8a from the photoreceptor surface, thereby cleaning the blade edge.

When you turn on the copy button to make a copy, the first B
As shown in the figure, the photoreceptor 1 starts rotating (S3).

At this time, the timer must not be counting up! (S4
), the copying operation immediately begins while the cleaning plate remains in pressure contact with the photoreceptor.

When the timer is counting up (S4), the cleaning plate has been evacuated from the photoreceptor and cleaned by this time, so the following operations are performed.

That is, at this time, a developing bias is applied.

The applied voltage at this time is set to be as high as possible, for example, 500V which is the maximum voltage. As a result, some of the positively charged toner present in the toner, which is mostly negatively charged, is transferred to the surface of the photoreceptor (Ss).

Of course, the amount of toner in this case is very small and can be ignored compared to the amount of toner consumed for image formation.

Next, wait 1 second and rotate the photoconductor until the tip of the toner adhesion surface slightly exceeds the cleaning device 8 (S
6).

At this point, press the cleaning plate against the photoreceptor (
S7).

As mentioned above, in this case, there is a small amount of toner in the area where the blade comes into pressure contact with the photoreceptor, so the lubricating effect of this allows the blade to slide smoothly without any problems such as curling up. can enter the state.

When the toner has adhered to the photoreceptor in the circumferential direction and around the semi-circumference, the developing bias is turned off (Ss).

After waiting approximately 2 seconds, the copying operation begins (Be) when all of the adhered toner has been removed by the cleaning plate.

(3) As described in detail, the present invention provides a cleaning device in which the cleaning blade can be brought into contact with and separated from the carrier, in which the next operation is started after one copying operation is completed. When the time until the start is relatively short,
Without separating the cleaning plate from the damaged area, a small amount of toner adhering to the blade edge is used as a lubricant for the blade at the start of the 11th operation, and when image forming operation is performed after a certain period of time. , by supplying a small amount of toner to the damaged and special holiday side, apply the toner to the cleaned blade and edge as follows:
It is applied before the start of work, and in any case, the blade edge can exhibit a stable cleaning function without causing insufficient lubrication due to lack of toner.

Since the amount of toner deposited on the edge of the light blade is extremely small, the toner required for image formation is not wasted.

[Brief explanation of the drawing]

Figures 1A and 1B are flowcharts showing the operation when the present invention is applied to a copying machine, Figure 2 is an explanatory diagram of main parts showing the operation of a copying machine to which the present invention is applied, and Figure 3 is a copy of the same. FIG. 1 is a side cross-sectional view showing the configuration of a cleaning device of the machine. 1... Photoreceptor, 2... Charger, 3... Developer,
5...Transfer charger, 8...Cleaning device, 8a
...Cleaning plate. , Patent Applicant Canon Co., Ltd. Agent Patent Attorney Emi Figure 1A Figure 1B: Figure 2

Claims (2)

[Claims] (1) In a cleaning device for an image forming apparatus that has a cleaning plate that can freely approach and separate from the surface of the image carrier, the above-mentioned A method for controlling a cleaning device that causes toner to adhere to the surface of an image carrier before starting the next image forming operation. (2) Claim 1 in which toner is attached to the image bearing member by applying a developing bias to the image forming apparatus.
A method for controlling the cleaning device described in Section 1.