JPH04109283A - Cleaning device - Google Patents

Abstract

PURPOSE:To improve the recovery rate of residual toner by applying a rotary roller with an AC bias which has a DC component with the opposite polarity from electrostatic charges of toner. CONSTITUTION:A bias power source 110 is a power source which utilizes, for example, an iron resonance transformer and connected to a commercial power source on its primary side to obtain the AC bias, generated by superposing an AC component of 500Hz - 10KHz in frequency and about 400 - 200V and preferably about 500 - 1,000V in P-P voltage upon a DC component of 300 - 500V with the opposite polarity from the toner, on the secondary side. This AC bias is applied to the rotary roller 101 through a metallic shaft 102. Thus, the AC bias is superposed to the rotary roller 101 of the cleaning device. Consequently, the recovery rate of the toner is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cleaning device for capturing and cleaning residual toner on the surface of an image forming body of an image forming apparatus such as an electrophotographic copying machine.

[Conventional technology]

Conventionally, cleaning devices for image forming bodies of image forming apparatuses include devices that brush the surface of the image forming body with a rotating brush to clean it, and devices that press the corners (ridge lines) of a blade made of hard urethane rubber or the like against the surface of the image forming body. A cleaning device that scrapes and cleans the toner remaining on the surface of the photoconductor;
A rotating roller made of an elastic body rotated in the opposite direction to the moving direction of the image forming body is pressed against the image forming body by applying a DC bias voltage having a polarity different from the potential of the toner to remove the residual toner. Cleaning devices that clean by wiping and adsorption are known.

[Problem to be solved by the invention]

A cleaning device consisting of a pre-rotating brush had a low toner recovery rate, and the recovered toner was scattered and could not be completely recovered, making it incomplete. In addition, although the cleaning device consisting of the blade has a high toner recovery rate and has the feature that the device has a simple structure, the blade tip tends to vibrate, causing the toner accumulated at the blade tip to remain on the surface of the image forming body. Both methods have the disadvantage that they can cause unsightly fogging and smudges on the copied image.

An object of the present invention is to solve these drawbacks and provide a cleaning device with a high toner recovery rate.

[Means to solve the problem]

The above object is a cleaning device in which a rotating roller made of an elastic body is brought into pressure contact with an image forming body, and the moving direction of the image forming body and the moving direction of the rotating roller are opposite to each other on the pressing surface, the rotating roller This is achieved by a cleaning device characterized by applying an alternating current bias having a direct current component having a polarity different from that of the toner.

〔Example〕

FIG. 1 is a sectional view showing an example of a copying apparatus to which the present invention is applied. In Figure I: 8, 1 is a photoreceptor drum, which is an image forming member having a photoreceptor layer provided on the drum surface, which is made of aluminum or the like, and is rotating in the direction of the arrow at a linear velocity of 1500110/See. Photoconductors such as zinc oxide, selenium, amorphous silicon, organic semiconductors, and CdS can be used as the photoreceptor.

A document table 31 made of a transparent glass plate or the like, and a document cover 32 that covers the document placed on the document table 31 are disposed at the top of the main body of the copying apparatus. The exposure lamp 11 and the first
A first mirror unit 5 comprising a mirror 12 is provided,
It is mounted parallel to the document tray 31 and movable linearly in the horizontal direction in the drawing, and optically scans the entire surface of the document tray. Reference numerals 13 and 14 are a second mirror and a third mirror, respectively, and the mirror 17 of the first mirror unit 5 is designed to maintain a predetermined optical path length of the second mirror unit 6 which is integrally fixed with the second mirror 13 and 14, respectively.
Moves in a straight line in the same direction left and right at a speed of 2. Of course, the movement of the second mirror unit 6 is parallel to the document table 31 similarly to the first mirror unit 5. The image of the document on the document table 31 is illuminated by the exposure lamp 11, and
The photosensitive drum l passes through the mirror 12, the second mirror 13, the third mirror 14, the main lens 15, and the fourth mirror 16.
It is designed to be incident upward. After scanning, the first
The mirror unit 5 and the second mirror unit 6 return to their original positions and wait until the next copy.

The photosensitive drum 1 rotates clockwise as shown by the arrow at the same time as copying starts, and the charger 2 applies a uniform charge to the surface of the photosensitive drum 1, so that the photosensitive drum l rotates clockwise as shown by the arrow. An electrostatic latent image corresponding to the image of the document is formed on the body drum 1.

After that, the electrostatic latent image of the document on the photoreceptor drum 1 is
The toner image is developed by the developing device 3 into a visible toner image.

Paper feed cassette that accommodates multiple sheets of recording paper P] From 4,
The recording paper P is fed out one by one by the first paper feed roller 41. This fed-out recording paper P is attached to the photosensitive drum l.
The toner image is sent onto the photoreceptor drum 1 by the second paper feed roller 42 which operates in synchronization with the toner image above.

Thereafter, the toner image on the photosensitive drum 1 is transferred onto the recording paper P by the action of the transfer device 7. After being separated from the photoreceptor drum L by the separator 8, the recording paper P is sent to the fixing device 9 via the recording paper conveyance means, where it is fused and fixed by a heat fixing roller and a pressure roller, and then by a paper ejection roller. It is ejected from the copying machine.

On the other hand, it is not transferred onto the surface of the photoreceptor drum 1 and remains on the photoreceptor drum l! ; After the toner is neutralized by the pre-cleaning charger 18 and the pre-cleaning exposure device 19, the toner is scraped off and cleaned by the cleaning device 10, and is ready for the next copying.

FIG. 2 is an enlarged sectional view showing an embodiment of the cleaning device 10 of the present invention used in the copying machine and the like shown in FIG. In the figure, 101 is a rotating roller, 105 is a blade, 108 is a case, 109 is a collection screw 11
0 is a bias power supply for applying a bias voltage to the rotating roller 101; 107 is a bias power source for applying a bias voltage to the rotating roller 1;
01 is the nip portion of the pressure contact portion.

The rotary roller 101 is made of NBR rubber, for example, and has an outer diameter of about 30 mm and has a resistivity of 10' Ω, for example, made of NBR rubber, which has an outer diameter of about 30 mm and has a resistivity adjusted to 1070 cm or less, around a metal shaft 102 made of stainless steel, for example.
A roller-shaped conductive elastic body 103 with a resistivity of 10' Ωcm or more, preferably 1014 Ωc, is provided, and its surface is made of a Mylar tube with a thickness of 10 to 100 μm.
m or less, and the surface is covered with an insulating film 104 having a roughness approximately equal to the diameter of the toner (approximately 20 μm).

Both ends of the metal shaft 102 are supported by bearings, which are rotated without being pressed by a spring 106, and the rotating roller 1
The second part rotates while being pressed against the photosensitive drum 1 while rotating in the opposite direction on the pressure contact surface to form a nip portion 107 having a nip width of 2 to 3 mm.

Note that for the triboelectrification series between the insulating film 104 of the rotary roller 101 and the toner, a material is selected that does not change the polarity of the electric charge of the toner from the beginning.

The bias power supply 110 is, for example, a power supply using a ferro-resonant transformer, whose primary side is connected to a commercial power supply, and whose secondary side is supplied with a DC component of 300 to 500 V having a polarity different from that of the toner, with a frequency of 500 H2 to 10 KHz, P-P voltage 400V~
It is intended to obtain an alternating current bias with a superimposed alternating current component of 2000 V, preferably about 500 to 100 OV.

This alternating current bias is applied to the rotating roller 1 via the metal shaft 102.
01.

If the voltage of the alternating current component is lower than the above range, the cleaning performance will be insufficient, and if the blade is too high, breakdown will occur between the blade and the photoreceptor, resulting in decreased cleaning performance and deterioration of the photoreceptor.

Next, the operation of this cleaning device [10] will be explained.

The photosensitive drum l, which has transferred the toner image onto the recording paper P, continues to rotate, and the pre-cleaning static eliminator 18. When the toner reaches the pre-cleaning exposure device 19, the toner on the photoreceptor drum l is charged with one polarity. When this toner reaches a position very close to the rotating roller 101, which is rotating in the opposite direction to the moving direction of the photosensitive drum 1, the toner vibrates due to the AC component of the AC bias applied to the rotating roller 101. It becomes easy to separate from the surface of the photoreceptor drum 1, is attracted to the rotation roller 101 side by the DC component of the AC bias at the nip portion 107, is stripped off from the photoreceptor drum 1, and is conveyed.

The toner conveyed by the rotating roller 101 is scraped off toward the bottom of the case 108 by a conductive blade 105 that comes into contact with the circumferential surface of the rotating roller 101 . The scraped off toner is transported by a transport screw 109 to a toner collection box (not shown) and collected.

Of course, it is also possible to recycle it to the developing device 3.

Regarding the amount of toner collected over a long period, when the bias applied to the rotary roller 101 of the cleaning device 10 configured as described above is only a DC component, and when the bias is applied to an AC bias having a DC component as described above, As a result of extensive comparisons, it was found that the toner recovery rate was improved by about 15% when AC bias was added compared to when only DC components were used.

Although the cleaning device described in this embodiment can be used alone to obtain good cleaning results, the surface cleaning of the photoreceptor drum 1 can be sufficiently effected by using it in combination with a cleaning device such as a blade. It has been recognized that this can be mentioned.

〔Effect of the invention〕

According to the present invention, with the above-described configuration, a cleaning device with an extremely high recovery rate of residual toner is provided by applying an alternating current bias having a direct current component having a polarity different from that of the toner charge to the rotating roller. be able to.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a copying apparatus to which the present invention is applied, and FIG. 2 is an enlarged sectional view showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Photosensitive drum 10... Cleaning device 101... Rotating roller 102... Metal shaft 103... Elastic body 104... Insulating film 1
05...Blade 106...Spring llO
...bias power supply

Claims (1)

[Scope of Claims] A cleaning device in which a rotating roller made of an elastic body is brought into pressure contact with the image forming body, and the moving direction of the image forming body and the moving direction of the rotating roller are opposite to each other on the pressure contact surface. A cleaning device characterized in that an alternating current bias having a direct current component having a polarity different from that of toner is applied to the moving roller.