JPH03241385A - Cleaning device - Google Patents

Abstract

PURPOSE:To prevent a toner from reattaching to the surface of an image bearing drum and staining the inside of a machine by causing air to flow in the direction reverse to the movement of the drum at the top of a cleaning blade when withdrawing the blade. CONSTITUTION:The cleaning blade 19A is pressed into contact with the circumference of the photosensitive drum 10 to rake down a remaining toner at the time of operating cleaning, and at the end of the raking the top E of the blade 19A is made a little apart from the circumference of the drum 10 and the cleaning operation is temporarily paused, and at the same time or slightly before, a motor M is started to rotate a propeller fan P to cause the air to flow in the direction reverse to the movement of the drum 10, and the toner powder and its blocks scattering or falling at the time of the separation are collected in a toner recovery holder in the case of the cleaning device 19 without attaching to the circumference of the drum 10, thus permitting the waste toner to be prevented from reattaching to the drum 10 and scattering in the inside of the device 19.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention provides a cleaning device used in a color image forming apparatus that superimposes a plurality of monochromatic toner images formed on an image carrier to synthesize a color toner image. Regarding.

[Conventional technology]

There are many ways to obtain color images using electrophotography.
A device has been proposed. For example, Japanese Patent Publication No. 61100770
As disclosed in the publication, a latent image is formed and developed on a photoreceptor drum serving as an image carrier according to the number of separated colors of the original image, and is transferred onto a transfer drum each time it is developed. One method is to form a multicolor image and then transfer it onto a transfer material to obtain a color copy. A device using this method requires a transfer drum large enough to transfer one sheet of image onto its circumferential surface in addition to the photoreceptor drum, and the device does not have a large and complicated structure. Inevitable.

Furthermore, as disclosed in JP-A No. 61-149972, for example, a latent image is formed and developed on a photoreceptor drum, which is an image carrier, according to the number of separated colors of the original image, and each time the development is performed, a latent image is transferred. This is a method to obtain a multicolor copy by transferring the image onto a material. With this method, it is difficult to overlap multicolor images with high precision, and it is impossible to obtain high-quality color copies.

Furthermore, there is a method of repeatedly forming a latent image on a photoreceptor drum according to the number of separated colors of an original image and developing it with color toner, and then transferring the color toner after superimposing it on the photoreceptor drum to obtain a color image. The basic process of forming a multicolor image is disclosed in Japanese Patent Application Laid-open No. 60-75850 and No. 60-75850 by the present applicant.
No. 76766, No. 60-95456, No. 60-954
No. 58, No. 60-158475, and the like. In a multicolor image forming apparatus that obtains a color image by such overlapping development, a high quality color image with few color streaks can be obtained.

In the image forming apparatus, after multicolor image formation is performed by overlapping development, the toner image formed on the photoreceptor drum is transferred onto transfer paper, and the remaining toner is cleaned and transferred to the next image. Preparations for image formation are made.

As a cleaning device, various methods and devices have been proposed, and recently, the end of a flat cleaning blade 119A as shown in FIG. A blade cleaning device is widely used in which residual toner is cleaned by pressing a cleaning and developing unit e, which is a contact portion of the blade, onto a photoreceptor drum 110, which is an image carrier.

As shown in FIG. 4(a), the blade cleaning device includes a counter type in which a support portion 119C of a cleaning blade 119A (hereinafter simply referred to as a blade) is located downstream with respect to the rotation of the photoreceptor drum 110, and a counter type in which a support portion 119C of a cleaning blade 119A (hereinafter simply referred to as a blade) is located on the downstream side with respect to the rotation of the photoreceptor drum 110; 4
As shown in Figure (b), the support portion 119 of the blade 119A
There is a trail type in which G is located on the upstream side. The counter type has a slightly better cleaning efficiency than the trail type, and the load on the image carrier at the contact point can be reduced, and there is less variation in the rotational speed of the image carrier, so it is used with less color misalignment. There are many things.

Although the blade 119A may remain pressed against the photoreceptor drum 110 at all times, for example, in the above-mentioned apparatus that performs overlapping development, the blade 119A may be separated from the photoreceptor drum 110 during the formation of a plurality of toner images. It is necessary to make it possible to press and release the material so that it can be pressed and cleaned after the transfer process is completed, and then separated again after cleaning is completed.

[Problem to be solved by the invention]

However, while the blade 119A presses against the photoreceptor drum 110 and performs the cleaning operation, the scraped toner powder adheres and accumulates on the contact portion of the cleaning edge e as shown in the figure. At the time of separation, a portion of the toner powder adhering to the contact portion of the edge e may be released and scattered in the rotational direction of the drum due to the movement of the air layer in contact with the drum.

As a result, toner adheres again to the drum surface after cleaning, resulting in so-called cleaning and development, which impairs subsequent image quality, or may enter the inside of the apparatus, causing contamination within the apparatus.

The present invention solves this problem and improves it by preventing the accumulated toner powder from adhering to the contacts of the cleaning edge e from moving and scattering in the direction of rotation of the drum, thereby preventing cleaning development and dirt inside the machine. The above object is to provide a cleaning device that has a cleaning blade in a cleaning case that moves toward and away from a rotating image carrier, in which the tip of the blade is removed when the cleaning blade is retracted from the image carrier. This is closely related to a cleaning device characterized in that it is configured to generate an air flow in a direction opposite to the moving direction of the image carrier.

〔Example〕

An embodiment of the present invention is shown in FIGS. 1 to 3.

Fig. 3 shows a color image forming apparatus incorporating the cleaning device of the present invention. Color images are formed through this process.

In the image reading section l, the document placed on the document table is illuminated and illuminated by a reading optical system that moves horizontally in synchronization with the rotational peripheral speed of the photoreceptor drum IO, which is an image carrier.
It is scanned, and the reflected light is guided to a lens reading section composed of a lens, a color separation prism or a color filter, a color CCD, and the like. The light reflected from the original is focused by the lens and formed into an image on the light-receiving surface of a CCD, which is a light-receiving element.

For example, the B, G, and H image signals output from the color CCD are subjected to color correction processing in the image information processing section, and the color-corrected color signals are processed according to the colors of the Y, M, and C toners T. It is outputted as follows and inputted to the laser writing section 2, which is an exposure means.

In the laser writing unit 2, the laser beam L generated by the semiconductor laser is rotated and scanned by a rotating polygon mirror, passes through an fθ lens, has its optical path bent by the mirror, and is charged in advance by a charger 14, which is a charging means. The circumferential surface of the photoreceptor drum IO thus obtained is scanned and exposed.

When scanning is started, modulation of the laser beam L by the first color signal is started, and the modulated laser beam L scans the circumferential surface of the photoreceptor drum 10.

Therefore, the main scanning by the laser beam L and the photosensitive drum 10
An electrostatic latent image of the first color is formed on the circumferential surface of the photosensitive drum 10 by the sub-scanning caused by the rotation of the photosensitive drum 10 . This latent image is reversely developed by a developing device 16 loaded with yellow (Y) toner, for example, to form a visible toner image. The obtained toner image, while being held on the photoreceptor drum IO, passes under a cleaning device 19, which is a cleaning means separated from the circumferential surface of the photoreceptor drum IO, and enters the next copy cycle.

In the next copy cycle, the photoreceptor drum 10 is charged by the charger 1.
4, the second color signal outputted from the image information processing section is input to the writing section 2, and the photosensitive drum 1 is charged again in the same manner as in the case of the first color signal described above.
Writing is performed on the zero circumferential surface and a latent image is formed. This latent image is reversely developed by a developing device 17 loaded with toner T of a second color, for example, magenta (M). This magenta (M) toner image is formed to be superimposed on the previously formed yellow (Y) color toner image.

The developing device 18 is a developing device containing cyan (C) color toner, and forms a cyan (C) toner image on the photoreceptor drum IO based on an image signal generated by the image information processing section.

A DC or DC and AC bias voltage is applied to the developing sleeves of each of the developing devices 16, 17, and 18, and non-contact development is performed in which the developing sleeve does not come into contact with the photoreceptor drum 10 using the two-component developer. It has become.

The color toner image thus formed on the circumferential surface of the photoreceptor drum IO is transferred to a transfer device 43 provided as a transfer means.
At this time, the image is transferred onto recording paper P, which is a transfer material, fed from a paper feed cassette 40 by a paper feed roller 41 and a registration roller 42 . Recording paper P to which the color toner image has been transferred
The toner image is separated from the photosensitive drum 10 by a separator 44, conveyed to a fixing device 46 via a conveyor belt 45, where the toner image is fixed, and is discharged from the apparatus as a completed copy image.

On the other hand, a photoreceptor drum l with the recording paper P separated from its circumferential surface
The plate 19A of the cleaning device 19 comes into contact with the drum 19 to remove the remaining toner T, and after that, it is pulled away from the drum circumferential surface again and a new color image forming process begins.

1 and 2 show the detailed structure of the cleaning device 19. FIG.

20 is a case of the cleaning device 19; 21 is a rotating shaft installed between both side walls of the case 20; the rotating shaft 21 is urged by an elastic member (not shown) to rotate counterclockwise within a predetermined angular range; Furthermore, it is designed to be reversed clockwise beyond the above range by receiving power from the main body of the device.

22 is a blade holder A fixed to the rotating shaft 21 with a screw; 23 is a blade holder B that is integrated with the blade holder A after adjusting its position via an adjusting screw 24; The blade 19A is attached to the drum surface by adhesive so as to be in pressure contact with the drum surface in a counter manner.

For example, urethane rubber with a hardness of about 70° is used for the blade 19A, and during the cleaning operation, the elasticity of the rubber and the urging force of the rotating shaft 21 press the tip E of the blade against the drum surface which rotates clockwise. Scrape off residual toner.

Reference numeral 19B denotes a metal toner collection roller installed below the blade 19A, which is rotated counterclockwise by the power of the main body of the apparatus during the cleaning operation at a position protruding from the drum surface with a small gap. The toner collection roller 19B receives the toner scraped off by the blade 19A on its peripheral surface and sends it to the toner collection section at the bottom of the case 20 via the scraper 25. In the toner collection section, a toner transport screw 26 rotates to transport the toner and store it in a collection container outside the case 20.

The case 20 has an intermediate wall 20B slightly above the center thereof.
The cleaning case 20 is divided vertically into two parts, and a relatively narrow ventilation path is formed between the upper wall 20A and the middle wall 20B, and a filter is provided at the opening at the left end of the air passage to filter out dust in the outside air. It is equipped with F1.

On the other hand, a filter F2 for filtering the toner in the case 20 is attached to the opening at the left end formed by the intermediate g20B and the lower wall 20G, and a propeller directly connected to the motor M is attached to the outside of the filter F2 for filtering the toner inside the case 20. A 7-amp is installed. The propeller fan P is located in the lower cleaning case 2.
It rotates in the direction of discharging the air inside.

In the cleaning device ff1i19, the blade 19A touches the photoreceptor drum 10 as shown in FIG. 1 during the cleaning operation.
The remaining toner on the photoreceptor after transfer is scraped off by pressing the peripheral surface of the photoreceptor, and the scraped toner is further conveyed to the toner collection section at the bottom.

When the residual toner has been removed, the rotating shaft 21 is rotated clockwise to rotate the blade 19A as shown in FIG.
The blade tip E is slightly spaced apart from the drum circumferential surface to temporarily interrupt the cleaning operation described above, forming a slit-like gap between the blade tip E and the drum circumferential surface.

At the same time or slightly before this, the motor M starts to rotate the propeller fan P, and due to the pressure reduction effect accompanying the rotation, an air flow as shown by the arrow is generated inside the case 20.

In other words, due to the rotation of the propeller 7A, a pressure difference is generated within the case 20 which is vertically divided by the intermediate wall 20B.
The outside air that has been filtered to remove dust and the like by the filter Fl is sucked into the case 20, and the sucked outside air further passes through the gap formed between the blade tip E and the drum surface to increase its speed and adhere to the blade 19A. The toner is forcibly sent in the direction of the arrow shown in FIG.

The above-mentioned air flow is an air flow in the opposite direction to the moving direction of the photoreceptor drum 10, and therefore, the wind force of the air flow is used to turn the flow of the air layer generated along the circumferential surface of the drum in the opposite direction of the rotation of the photoreceptor drum 10. Therefore, toner powder and toner lumps that scatter or fall when the blade 19A is separated can be collected and stored in the toner collecting section in the case 20 without adhering to the drum surface.

The filters F1 and F2 are cleaned or replaced with new ones from time to time during long-term use in order to constantly maintain the above-mentioned air flow.

In this embodiment, a cleaning device using a counter-type blade has been described, but the present invention can produce similar effects even when applied to a cleaning device equipped with a trail-type blade.

〔Effect of the invention〕

The present invention provides a cleaning device that prevents the waste toner removed by the cleaning blade from adhering to the photoreceptor or scattering into the machine, and also enables more efficient collection of the waste toner. It has become possible to realize an image formatting device that can always stably obtain high-quality images without stains.

[Brief explanation of drawings]

1 and 2 are cross-sectional views of a cleaning device of the present invention, FIG. 3 is a configuration diagram of an image formatting device equipped with the cleaning device, and FIG. 4 is an explanatory diagram showing a pressure contact type of a cleaning blade. 10... Photosensitive drum 19A... Blade 20... Case 21... Rotating shaft 23... Blade holder B 25... Scraper 26... Toner conveying screw E... Blade tip P. ...Propeller fan 19...Cleaning device 19B...Toner collection roller 20B...Intermediate wall 22...Blade holder A Fl, F2...Filter M...Motor

Claims (2)

[Claims] (1) In a cleaning device having a cleaning blade in a cleaning case that moves toward and away from a rotating image carrier, when the cleaning blade is retracted from the image carrier, the tip of the blade moves in the direction of movement of the image carrier. A cleaning device characterized in that it is configured to generate an air flow in a direction opposite to that of the cleaning device. (2) The cleaning according to claim 1, wherein the air flow is generated by dividing the cleaning case into two with the cleaning blade as a boundary, and providing an intake fan in the upstream case to reduce the pressure. Device.