JPH02262180A - Cleaning device for image forming device - Google Patents

Abstract

PURPOSE:To prevent the lowering of transfer efficiency and to always ensure stable image formation by disposing a cleaning roller on the downstream of a cleaning blade, and rubbing an image carrier with a specific rate to the number of copies. CONSTITUTION:The cleaning blade 21 is disposed on the downstream and the cleaning roller 22 is disposed on the upstream respectively while rubbing the surface of a transfer intermediate body 5 as the travelling image carrier. A functional high polymer layer of excellent non-adhesion and sliding character is formed on the surface of the cleaning roller 22. The timing when the cleaning roller 22 rubs the surface of the image carrier 5 is n-times/m-copies (m>n). Consequently, such a toner filming layer that gives an adverse influence to a second transfer can be surely removed and the adverse influence to a first transfer due to excessive rubbing, etc., can be prevented. Thus, transfer performance is stabilized and a preferable image quality can be maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a cleaning device for an image carrier used in an image forming apparatus such as an electrostatic transfer copying machine or a laser printer.

<Prior Art> Conventionally, in this type of copying machine, a device for cleaning an image bearing member, such as a photoreceptor or a transfer intermediate, to which toner adheres and must be cleaned before the next image forming cycle is used. There are a blade cleaning method in which the edge of urethane rubber is pressed to scrape off the toner, and a fur brush cleaning method in which a bristle brush is used.

In particular, the blade cleaning method is mechanically simple,
Moreover, because it is inexpensive, it is widely used.

By the way, in the case of full-color copying machines, it is necessary to use toner with a particularly low melting point, so if toner melts due to heat or pressure, etc. and occurs on the photoreceptor or transfer intermediate, it cannot be removed completely with the blade alone, and it gradually melts. Since a filming layer is formed on the paper, transfer performance deteriorates and image quality deteriorates.

Particularly in the case of a double transfer method using a transfer intermediate, even a slight amount of filming significantly reduces transfer efficiency.

In order to improve this problem, the applicant has proposed a cleaning device in which a cleaning roller is provided on the downstream side of the cleaning blade, the surface of which is coated with a functional polymer layer with excellent non-adhesive and sliding properties. did.

<Problems to be Solved by the Invention> However, in the case of the cleaning roller of the cleaning device proposed above, the ability to remove the toner filming layer is very good, but if the image bearing member is rubbed too much, the following There was a problem like this.

■ Scratches occur on the image carrier and appear as white streaks on copies.

■ The fluororesin on the surface of the cleaning roller transfers onto the transfer intermediate sheet (Az), and the releasability of the sheet from the toner increases, which causes the toner image to be transferred from the photoreceptor belt to the transfer intermediate sheet (V). Transfer (first transfer) performance deteriorates significantly.

■ Accelerates abrasion of the transfer intermediate, resulting in uneven reduction in image density.

In view of the above, an object of the present invention is to provide a cleaning device that has stable transfer performance and can maintain good image quality.

<Means for Solving the Problems> The present invention provides a cleaning blade disposed on the upstream side of the image carrier to rub the surface of the image carrier, and a cleaning blade disposed on the downstream side of the image carrier. a cleaning roller disposed to rub the body surface; a means for bringing the cleaning roller into contact with and away from the image carrier;
n) means for driving and controlling the approaching and separating means at a rate of n).

Effect> The timing at which the cleaning roller rubs the surface of the image carrier is reduced to once every m copies (m>n), which reduces the toner fipping layer that adversely affects the second transfer. It is possible to reliably remove the toner and prevent any adverse effects on the first transfer due to excessive rubbing.

<Example> Hereinafter, a color copying machine will be described as an example of a cleaning device for an image forming apparatus according to the present invention.

FIG. 1 is a front view showing an embodiment of a cleaning device for a copying machine according to the present invention, FIG. 2 is a configuration diagram of a cleaning roller, and FIG. 3 is a front view of a full-color copying machine using the cleaning device according to the present invention. Schematic diagram, Figure 4 shows solenoid 3
FIG. 6 is a control circuit diagram of No. 6.

First, the configuration of a color copying machine using the cleaning device of the present invention will be explained with reference to FIG.

In the figure! Reference numeral 1 indicates a transparent document mounting table, 2 indicates an exposure optical system, 3 indicates a sheet-shaped photoreceptor, 4a to 4c indicates a developing tank for each color component, 5 indicates a sheet-shaped transfer intermediate, and 6a and 6t) indicate a size. paper feed cassette, 7 is a charger, 8a+
8b is a transfer charger, 9 is a plate-shaped separation charger, i
o indicates a fixing portion, respectively.

The exposure optical system 2 is configured to expose an original 11 placed on an original placing table l.
A light source lamp 2a that irradiates light to the original, a plurality of reflecting mirrors 2b that guide reflected light from the original 11 onto the photoreceptor 3 as shown by the dashed line, an imaging lens 2c disposed on the optical path, and three primary colors. (Red-green.

The color separation filter 2d has a color fill (blue).

The photoreceptor 8 is rotationally driven by two rollers 12a and 12b, and developer tanks 4a to 4c are arranged near the center of the upper surface of the photoreceptor 3 in a non-contact manner. A charger 7 is provided on the first roller 12a side of the photoreceptor 3.
A cleaning mechanism 13 for removing toner remaining on the photoreceptor 3 is provided on the lower surface of the photoreceptor 3 on the side of the first roller 12a.

The transfer intermediate body 5 is rotationally driven by three rollers 14a to 14c, and is disposed on the second roller 12b side of the photoreceptor 8. The second roller 12b side of the photoreceptor 3 is pressed against one side of the transfer intermediate 5, and the first transfer roller 8a is disposed on the back side of the transfer intermediate 5 in the area where the photoreceptor 3 is pressed. be done. Further, a second transfer roller 8b and a separation charger 9 are arranged on the lower surface of the transfer intermediate body 5. In the figure, 15 is a recording medium (paper);
16 indicates a conveyance path.

A cleaning device 20 according to the present invention is arranged on the transfer intermediate 5 as an image carrier.

As shown in FIGS. 1 and 8, this cleaning device 20 includes a cleaning blade 21 on the upstream side and a cleaning roller 22 on the downstream side for rubbing against the surface of the transfer intermediate 5 as a moving image carrier. A functional polymer layer 23 having excellent non-adhesion and sliding properties is formed on the surface of the cleaning roller 22.

The cleaning blade 21 is made of urethane rubber and is held by a holder 24, as shown in FIG.

A blade driving device 25 is provided to bring the cleaning blade 21 into contact with and away from the transfer intermediate 5. As shown in FIG.
4 and a solenoid 2 that is connected to the support piece 27 at one end and moves the cleaning blade 21 in the direction of contacting the transfer intermediate 5.
8, and a spring 29 whose one end is connected to the support piece 27 and urges the cleaning roller 21 in the direction away from the transfer intermediate body 5.

After the yellow, magenta, and cyan toners are transferred from the photoreceptor 8 in this order, the blade 21 is separated from the transfer intermediate 5 until the toner is transferred to the recording medium (paper).
After the transfer to the recording medium is completed, the blade 21 is configured to come into pressure contact with the transfer intermediate and scrape off the toner.

The cleaning roller 22, like the cleaning blade 21, can freely come into contact with and separate from the transfer intermediate 5,
The direction of rotation is opposite to the direction in which the transfer intermediate body 5 travels.

As shown in FIG. 1, the roller driving device 31 for bringing the cleaning roller 22 into contact with and away from the transfer intermediate 5 includes a case 33 that accommodates and supports the cleaning roller 22 and swings around a support shaft 32, and a case 33 that accommodates and supports the cleaning roller 22 and swings around a support shaft 32. a cam 35 that contacts the back surface of the case 83 and swings around the shaft 84; a solenoid 36 that moves the cam 35 in the roller contact direction;
3 in the roller separation direction.

As shown in FIG. 2, the cleaning roller 22 includes a core metal part 38, a sponge rubber roller body 89 fixed to the outer periphery of the core metal part 88, and a roller body 89 formed on the outer surface of the roller body 89. and the functional polymer layer 28.

The functional polymer layer 23 is made of fluororesin, and FIG. 4 is a block circuit diagram for driving and controlling the solenoid. In the figure, 86 is a solenoid of the roller drive device 81;
41 is a copy sensor that outputs a detection signal every time one copy is made; 42 is a central processing unit (CPU); and 48 is a solenoid drive section. The central processing unit 42 counts the output signals from the copy sensor 41 and processes the copies m.
In total, n (m>n) solenoid drive signals a are output to the solenoid drive unit 48.

The number of times the solenoid 86 is driven, that is, the number of times the cleaning roller 22 rubs against the image carrier 5 is set to, for example, (a) once every 10 copies (10 (2nd sheet), (b) 2 for every 10 copies
times (9th and 10th sheets), (c) 3 times for 20 copies (
18th, 19th, and 20th).

The operation of the color copying machine with the above configuration will be briefly described.

First, the original 11 placed on the original placing table 1 is placed on the light source 2a.
The optical image is irradiated and scanned several times, and the optical image is separated into color components by the reflecting mirror 2b via the imaging lens 2c and the color separation filter 2d.

The optical images of each color component transmitted through each color filter of the color separation filter 2d in several scans are sequentially image-exposed onto a photoreceptor 8 which is uniformly charged by a charger 7. The latent images for each color component created in order here are developed with respective developers in developer tanks 4a to 4c containing developers of complementary colors (yellow, magenta, cyan) to each of the color filters 2d of the color separation filters. After being visualized, the images are sequentially transferred onto the intermediate body 5 by the first transfer roller 8.

In this way, by overlapping toner images for each color component on the transfer intermediate 5, one completed color toner image is created.

This color toner image is taken out from one of the paper feed cassettes 6a and 6b, and is transferred to the recording medium 15 that is brought into close contact with the lower surface of the transfer intermediate 5 by the transfer roller 8b.
It is transcribed by . Thereafter, the recording medium 15 is separated from the transfer intermediate 5 by the separation charger 9, and introduced into the fixing section 10 via the conveyance path 16, where the color image transferred to the recording medium 15 is fixed.

A high voltage is applied to the surfaces of the first and second transfer rollers 8a+8b during transfer. Further, the second transfer roller 8b is in pressure contact with the transfer intermediate body 5 only when transferring to the recording medium 15, and is separated from the transfer intermediate body 5 when not transferring.

After the yellow, magenta, and cyan toners are transferred in this order from the photoreceptor 3 to the transfer intermediate 5 as an image carrier, the blade 21 is used until the toner is transferred to the recording medium (paper). The blade 21 is separated from the intermediate body 5 after the transfer to the recording medium 15 is completed.
to scrape off the toner.

In this way, when the number of copies reaches 10, for example,
A signal a is output from the CPU 42, and in response to this signal, the solenoid drive section 43 outputs a signal A for a certain period of time to drive the solenoid 36. Therefore, the cleaning roller 22 is pressed against the transfer intermediate body 5 against the spring 37, rotates in the opposite direction to the transfer intermediate body 5, and cleans the toner that has passed through the blade 21. When the cleaning is completed (after a certain period of time has elapsed), the solenoid 36 is turned off, and the cleaning roller 22 is separated from the transfer intermediate 5 by the biasing force of the spring 37.

By the way, the reason why the cleaning blade 21 is arranged on the upstream side and the cleaning roller 22 is arranged on the downstream side is as follows. That is, the cleaning blade 21 is effective when a thick amount of toner remains, but cannot clean when a thin film of toner remains on the transfer intermediate.

On the other hand, the cleaning roller 22 has no effect when a thick amount of toner remains, and has a cleaning effect when toner remains in the form of a film.

Therefore, the cleaning blade 21 is disposed upstream to first roughly remove the toner, and then the toner remaining in the form of a film on the transfer intermediate 5 is removed by the cleaning roller 21.
By removing in Step 1, cleaning can be performed effectively.

The reason why the cleaning roller 21 is coated with a soft sponge rubber roller body 39 on the core metal part 88 and further has a fluororesin layer 23 formed thereon is as follows. That is, when the roller surface is coated with synthetic rubber (urethane, silicone), toner tends to adhere and is difficult to remove.

On the other hand, in the case of fluororesin, toner is difficult to adhere to and is easy to remove.

It should be noted that the present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

For example, in the above embodiments, a transfer intermediate is used as the image carrier, but the image carrier is not limited thereto, and may be a photoreceptor. Further, the image carrier is not limited to a sheet-like one as in the above embodiment, but may be a drum-like one.

<Effects of the Invention> As is clear from the above description, according to the present invention, a cleaning roller is disposed downstream of the cleaning blade, and the cleaning roller is used for each m copies at a rate of n days (m>n). Since the image carrier is rubbed, the number of times the cleaning roller is rubbed can be effectively reduced. Therefore, a decrease in transfer efficiency is prevented,
A cleaning device that can always ensure stable image formation can be provided.

[Brief explanation of drawings]

FIG. 1 is a front view showing an embodiment of a cleaning device for a copying machine according to the present invention, FIG. 2 is a configuration diagram of a cleaning roller, and FIG. 8 is a schematic diagram of a full-color copying machine using the cleaning device of the present invention. , Figure 4 is a solenoid drive control circuit diagram. 5 is a transfer intermediate, 21 is a cleaning blade, and 22 is a cleaning roller.

Claims (1)

[Claims] (1) A cleaning blade disposed on the upstream side of the image carrier to rub the surface of the image carrier, and a cleaning blade disposed on the downstream side of the image carrier to rub the surface of the image carrier. a cleaning roller, a means for moving the cleaning roller toward and away from the image carrier, n times for every m copies (m>n);
A cleaning device for an image forming apparatus, comprising means for driving and controlling the approaching and separating means at a ratio of .