JPH0160148B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cleaning device for an electrostatic recording device that can always obtain a stable cleaning effect without being affected by the environment.

In electrostatic image recording devices such as electrophotographic copying machines and facsimile machines, an electrostatic latent image of the original or electrical information is created on a photoreceptor or dielectric material using reflected light or electrical information signals obtained by exposing and scanning the original. The electrostatic latent image is developed into a visible image, and this visible image is transferred to recording paper and then fixed to form a recorded image. FIG. 1 shows a schematic configuration of a conventional electrophotographic copying machine. A document G placed on a document table 1 moving in the direction of an arrow (solid line) is irradiated with an illumination lamp 2, and light reflected from the document G is emitted. is projected onto the photoreceptor 3a of the rotating drum 3 rotating in the direction of the arrow, thereby forming an electrostatic latent image of the document G on the photoreceptor 3a. Around the rotating drum 3, there are a charging electrode 4 for uniformly charging the photoreceptor 3a, a developing device 5, a transfer electrode 6, a separating electrode 7, a neutralizing electrode 8, and a cleaning device 9 (fur brush type). are arranged sequentially. The electrostatic latent image is developed into a visible image by a developing device 5, and the visible image is transferred by a transfer electrode 6 onto recording paper P fed by a conveying device 11 from a paper feeding device 10 such as a cassette. After the transfer, the recording paper P is separated from the photoreceptor 3a by the separation electrode 7, and transferred to the conveyance device 12.
The paper is conveyed to the fixing device 13, where it is fixed, and the paper is discharged onto the paper discharge tray 14.

In the above apparatus, in order to be able to use the photoreceptor 3a repeatedly, it is necessary to remove the charge and toner remaining on the surface of the photoreceptor 3a after the transfer process in the series of electrophotographic processes,
Residual charges are removed by a static elimination electrode 8, and residual toner is removed by a cleaning device 9.

Various cleaning devices are known for use in electrophotographic copying machines, such as a fur brush type, a blade type, and a magnetic brush type. The fur brush type continuously rotates a fur brush made of rabbit or other animal hair or synthetic fibers to remove toner remaining on the surface of the photoreceptor. This method involves brushing off the toner with a plate (called a fritz carver), vacuuming the toner, or sucking it up with a fan, and collecting it with a filter. The blade method is a method in which a blade made of elastic synthetic resin is pressed against the surface of the photoreceptor to remove residual toner. On the other hand, in the magnetic brush type, a non-magnetic cylindrical sleeve in which groups of magnets with different polarities are arranged alternately is provided close to the surface of the photoreceptor, and either the carrier is attracted to the cylindrical sleeve and rotated, or the group of magnets is rotated. In this method, the toner remaining on the surface of the photoreceptor is adsorbed and removed, and the toner on the sleeve surface is scraped off with a blade or the like and collected. In recent years, as copying machines have become faster and the moving speed of the photoreceptor has increased, the blade method may not be able to perform sufficient cleaning, so the fur brush method has been used in high speed copying machines. In addition, the fur brush in particular does not press the surface of the photoreceptor, especially the selenium drum, like a blade, so it does not cause scratches, and it also prevents small to solid objects from adhering to the blade and causing scratches, which extends the life of the photoreceptor. It has the advantage of being possible. For these reasons, fur brush type cleaning devices tend to be used favorably.

In conventional fur brush type cleaning devices, the fur brush is rotated at high speed so as to scrape the surface of the photoreceptor to wipe off the toner remaining on the surface of the photoreceptor, and the toner adhering to the brush fibers comes into contact with the brush fibers. The toner is brushed off with a frit cover provided in a manner similar to the above, and the brushed off toner is sucked up with a fan and collected with a filter. However, using a fan to suck the toner requires a large space, so instead, an electrically biased electrode member (hereinafter referred to as the "recovery roller") is rotated so that it comes into contact with the brush fibers of the fur brush. Then, the toner adhering to the brush fibers is electrostatically transferred onto a collection roller and scraped off by a toner scraping blade provided in contact with the collection roller (for example, Japanese Patent Publication No. 49-20228).

In a fur brush type cleaning device using such a collection roller, the toner electrostatically attached to the brush fibers is adsorbed to the brush fibers by utilizing the triboelectric charging properties of the brush fibers of the fur brush.
Since the electrostatic adsorption force between the brush fibers and the toner on the surface of the photoconductor is relatively strong, the toner adhering to the brush fibers does not completely transfer to the collection roller. As a result, the brush fibers become stained with toner, which weakens the electrostatic adsorption force between the brush fibers and the toner, making it impossible to obtain a stable cleaning effect. On the other hand, since the triboelectric charging of brush fibers is easily affected by humidity,
There is a problem in that the charged potential of the brush fibers varies greatly depending on the environment, and when the humidity is high, the charged potential of the brush fibers decreases, making it impossible to obtain a sufficient cleaning effect.

Therefore, a method of applying a potential to the brush fibers using conductive brush fibers instead of insulating brush fibers has been considered, but in this case, the condition of the toner attached to the brush fibers and the relationship between the brush fibers and the collection roller Since the contact state of the brush fibers is not always constant, the potential of the brush fibers changes and a stable cleaning effect may not be obtained.

The present invention has been made in view of the above-mentioned points, and it is possible to clean powder developer remaining on an image forming support such as a photoreceptor or dielectric using a fur brush, and remove powder developer stuck to the fur brush. In this cleaning device, the fur brush is formed as a conductive brush, and the conductive brush is grounded via a nonlinear resistance element.

By doing so, it is possible to always obtain a stable cleaning effect without being affected by the environment, and moreover, it is possible to reduce toner stains on the fur brush.

The present invention will be explained below based on the drawings.

FIG. 2 is a schematic diagram showing the configuration of the fur brush type cleaning device, in which 3 is a rotating drum having a photoreceptor 3a, 8 is a static elimination electrode, and 9 is a cleaning device. The cleaning device 9 has a brush core 91a and a brush core 91a surrounded by conductive brush fibers 91b made of synthetic fibers mixed with carbon, etc., and is rotated by a motor _M1 .
1, a nonlinear resistance element such as a varistor 92 whose one end is connected to the fur brush 91 and the other end is grounded, and a voltage is applied from the power source E and the motor
a conductive collection roller 93 rotated by _M2 ;
It consists of a toner scraping blade 94 provided in contact with a collection roller 93.

Now, in the cleaning device with the above configuration,
When a bias voltage of 1 kV is applied to the recovery roller from the power source E, and the varistor 92 is used so that the voltage becomes 600V regardless of changes in current, the varistor 92 has a recovery roller 93 and conductive brush fibers 91b. A current flows through the brush fibers 91b, and the potential of the brush fibers 91b is constant at 600V. Therefore, the potential difference between the brush fibers 91b and the photoreceptor 3a is
It becomes 600V. As a result, the potential difference between the brush fibers 91b and the collecting roller 93 becomes 400V.

To remove toner with such a device,
The fur brush 91 is rotated at high speed in the direction of the arrow so as to rub against the rotating drum 3 rotating in the direction of the arrow, and the toner adhering to the surface of the photoreceptor 3a is electrostatically adhered to the brush fibers 91b. The toner is electrostatically transferred to a collection roller 93 rotating in the direction of the arrow in contact with the brush fibers 91b, and scraped off by a toner scraping blade 94.

As described above, in this embodiment, by connecting the varistor 92 to the fur brush 91, the electric potential of the brush fibers 91b is set to a predetermined constant value, and the electric potential difference between the brush fibers 91b and the photoreceptor 3a and the difference between the brush fibers 91b and the brush fibers 91b are controlled. The potential difference between the collecting roller 93 and the collection roller 93 can be kept constant. Therefore, the electrostatic adsorption force between the brush fibers 91b and the toner on the photoreceptor 3a is always approximately constant, and most of the toner is transferred to the brush fibers 91b. Also brush fiber 9
Since the electrostatic adsorption force between the toner attached to 1b and the collection roller 93 is always almost constant, the toner is reliably transferred to the collection roller 93 and the toner can be collected reliably. Therefore, a stable cleaning effect can always be obtained without being affected by the environment. Further, toner staining on the brush fibers 91b can be prevented.

In addition, considering the toner collection effect, the potential difference between the brush fibers 91b and the collection roller 93 is preferably 300V to 500V, and if it is within this range, the toner attached to the brush fibers 91b can be sufficiently transferred to the collection roller 93. be able to. Further, if the bias voltage of the collection roller 93 is set to 700V or less, the toner collection effect will be reduced, so it is appropriate that the bias voltage is set to 800V to 1000V. Here, even if the voltage of the power source E is increased, the bias voltage of the collection roller 93 will not increase, only an excessive current will flow, and the toner collection effect will not be improved. On the other hand, the potential of the brush fibers 91b is determined by the voltage of the varistor 92 having a desired voltage.
It is best to apply a voltage of 500V or more to b, so the voltage should be selected within the range of 500V to 600V.

In the above embodiment, a varistor is used as the nonlinear resistance element, but the present invention is not limited to this, and a Zener diode or the like may also be used.

Of course, the cleaning device according to the present invention can be used not only for photoreceptors but also for image forming supports such as dielectric materials.

As explained above, the present invention uses a fur brush to clean powder developer remaining on an image forming support such as a photoreceptor or dielectric, and electrically removes the powder developer adhering to the fur brush. In a cleaning device that collects with a biased roller, the fur brush is formed as a conductive brush, and the conductive brush is grounded via a nonlinear resistance element. By doing so, it is possible to always obtain a stable cleaning effect without being affected by the environment, and moreover, it is possible to reduce toner stains on the fur brush.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an electrostatic recording device, and FIG. 2 is a schematic diagram of an embodiment of a fur brush type cleaning device according to the present invention. 1... Document table, 2... Illumination lamp, 3... Rotating drum, 4... Charging electrode, 5... Developing device, 6...
Transfer electrode, 7... Separation electrode, 8... Static elimination electrode, 9
... Cleaning device, 10 ... Paper feeding device, 1
1, 12... Conveying device, 13... Fixing device, 14
... Paper discharge tray, 91 ... Fur brush, 91a ...
Brush core, 91b... Brush fiber, 92... Varistor, 93... Collection roller, 94... Toner scraping blade.

Claims (1)

[Claims] 1. In a cleaning device that uses a fur brush to clean toner remaining on an image forming support using an electrostatic image recording method, and collects the toner adhering to the fur brush with an electrically biased roller, the fur brush is used as a conductive brush. A cleaning device characterized in that the conductive brush is grounded via a nonlinear resistance element.