JPH0259471B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for removing residual toner from a photoreceptor of an electrophotographic copying machine.

In an electrophotographic copying machine that attracts charged toner to an electrostatic latent image formed on a photoreceptor to form a developed image and transfers it to copy paper, it is necessary to use the photoreceptor repeatedly. Toner remaining on the surface of the photoreceptor must be removed. A cleaning device is used to do this, and conventional cleaning devices include a rotating brush type, a blade type, and a magnetic brush type.

Since the present invention relates to an improvement of the magnetic brush type cleaning device, first, the conventional device will be explained.

FIG. 2 shows a conventional cleaning device described in Japanese Patent Publication No. 48-37382. 13
is a drum photoreceptor which rotates in the direction of the arrow, and residual toner 11 is adsorbed on its surface. 20
The magnetic brush device is composed of a non-magnetic metal sleeve 22 and a permanent magnet 24, similar to the magnetic brush in the developing device. Sleeve 22
rotates about an axis 26 as shown by the arrow, and the permanent magnet 24 is fixedly disposed in the position shown. plate 32
The magnetic carrier 28 housed in the sleeve 28 is the same as the carrier used for two-component developer, and is attracted to the circumferential surface of the sleeve 22 by the attractive force of the permanent magnet 24, and as it rotates. It is transported as if it were a long time ago.

A corona discharger 35 acts toward the circumferential surface of the photoreceptor 13 . The polarity of the power source 37 of the corona discharger 35 is selected so as to discharge the same polarity as the charged polarity of the toner 11 on the photoreceptor 13. A voltage having a polarity opposite to that of the toner 11 is applied to the sleeve 22 by a power source 30 .

The carrier 28 on the circumferential surface of the sleeve 22 stands up like a spike near the magnetic pole of the permanent magnet 24 and becomes a magnetic brush, and as a result of moving as the sleeve 22 rotates, the toner on the circumferential surface of the photoconductor 13 is removed. 11
is in sliding contact with the carrier 28. At this time, the toner 11 receives electrostatic attraction force due to the voltage applied to the sleeve 22 and is attracted to the carrier 28.
The toner 11 on the photoreceptor 13 is removed and cleaning is performed.

The carrier 28 that has absorbed the toner 11 moves as the sleeve 22 rotates, and stands up again in the shape of a spike at a position 180 degrees away. A metal drum 40 that rotates in the direction of the arrow is provided at that position, and a voltage is applied to it by a power source 44. Since this voltage is more than twice the voltage applied to the sleeve 22, the toner 11 is taken away from the carrier 22 that comes into contact with it. Thus, the toner 11 adsorbed on the metal drum 40 is conveyed as the metal drum rotates, scraped off by the blade 50 that presses against the peripheral surface of the metal drum 40, and collected in the collection container 52.

By the way, in the conventional device, it is necessary to apply a voltage of 200 to 1000 V to the sleeve 22, and since it is necessary to provide a potential difference between the metal drum 40 and the sleeve 22, a voltage higher than that is applied to the metal drum 40. It is necessary to apply a voltage of 1000-2000V. However, when such a high voltage is applied, leakage occurs through the carrier, and smooth operation cannot be expected.

The present invention aims to solve the above-mentioned problems by separately providing a magnetic brush device that attracts toner from a photoreceptor and a toner recovery device that separates toner from a carrier. It is characterized by a structure in which a carrier circulates between the two.

Next, the present invention will be explained based on the embodiment shown in FIG. The drum-shaped photoreceptor 13 rotates in the direction of the arrow and reaches the opening 7a of the cleaning device 7 with the negatively charged residual toner 11 attached thereto. A non-magnetic metal sleeve 1 having a permanent magnet 15 fixed therein is disposed within the opening 7a.
It is rotating counterclockwise. 2 and 3 are relay sleeves, both of which are made of non-magnetic material and have permanent magnets 16 and 1 inside like the sleeve 1.
7 are fixedly arranged.

Relay sleeve 2 is arranged diagonally above sleeve 1 and rotates clockwise. Relay sleeve 3
is arranged above the relay sleeve 2 and rotates counterclockwise. Each of these sleeves 1, 2, 3 is
By rotating while attracting the magnetic carrier 28 to its peripheral surface, the carrier 2 shown by arrows A, B, and C is
8 circulation paths are formed, and its operation is similar to that of a pumping sleeve in a developing device.

A scraper 8 acts on the circumferential surface of the relay sleeve 3, whereby the carrier 28 separated from the circumferential surface of the relay sleeve 3 falls to the upper part of the sleeve 1 and accumulates there. This carrier 28 is attracted to the circumferential surface of the sleeve 1 with a thickness regulated by the doctor 6, serves as a magnetic brush, sweeps the surface of the photoreceptor 13, and circulates through the circulation paths A, B, and C.

A toner collection roller 4 and a counter electrode 5 are arranged to face each other along the flow path C of the carrier 28,
The carrier 28 flows down between them. The toner collection roller 4 rotates in the direction of the arrow, and the blade 9 is in pressure contact with it. A collected toner discharge device 10 is arranged below the blade 9.

A positive voltage of 200 to 500 V (opposite polarity to the toner) is applied to the sleeve 1 by a power source 12, and the same voltage is applied to the toner collection roller 4 by a power source 14. The counter electrode 5 is grounded. As a result, the distance between the toner collection roller 4 and the counter electrode 5 is 1000~
An electric field of about 5000V/cm can be obtained.

Prior to cleaning, the photoreceptor 13 is subjected to static neutralization by a corona discharger 35. As a result, the electrostatic latent image on the photoreceptor 13 is neutralized, and the amount of negative charge on the toner 11 increases. When the magnetic brush by the carrier 28 formed on the circumferential surface of the sleeve 1 sweeps the circumferential surface of the photoreceptor 13, the negatively charged toner 11 is attracted by the positive voltage applied to the sleeve 1 and is attracted to the carrier 28. do. This carrier 28 is baton-touched by the relay sleeves 2 and 3 and is conveyed as shown by arrows A, B, and C. When flowing down the downstream path C, it passes between the collection roller 4 and the counter electrode 5, where it is subjected to the action of an electric field. This electric field separates the negatively charged toner 11 from the carrier 28 and attracts it to the collection roller 4. The toner 11 attracted to the collection roller 4 is conveyed as the collection roller 4 rotates, is scraped off by the blade 9, and collected in the collected toner discharge device 10. The carrier 28 separated from the toner 11 is the sleeve 1
Flows upward and recirculates. In addition, corona discharger 3
5 may not be provided.

As described above, the present invention provides an apparatus for electrostatic cleaning using a magnetic brush formed by a magnetic carrier, including a relay sleeve for conveying a toner-bearing magnetic carrier adsorbed to the circumferential surface of the sleeve forming the magnetic brush; It has an electrode that applies an electric field to the toner-bearing magnetic carrier separated from the circumferential surface of the relay sleeve, and a toner collection roller, and the magnetic carrier from which toner has been removed is returned to the sleeve of the magnetic brush device. The toner collecting roller can be made electrically independent, and there is no need to apply a high voltage to the toner collecting roller on top of the voltage applied to the magnetic brush forming sleeve. As a result, inconveniences due to leakage can be eliminated and insulation becomes easier. Further, as a result of providing the relay conveyance means, the carrier circulation path becomes longer and the amount of carriers included therein increases, so that fatigue of the carrier is reduced.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an embodiment of the present invention, and FIG. 2 is a front view of a conventional cleaning device. 1... Magnetic brush forming sleeve, 2, 3... Relay sleeve, 4... Toner collection roller, 5...
Counter electrode, 8... Screver, 11... Toner,
13...photoreceptor, 28...carrier.

Claims (1)

[Claims] 1. In an apparatus that performs electrostatic cleaning using a magnetic brush formed by a magnetic carrier, a relay sleeve that conveys a magnetic carrier with toner adsorbed to the circumferential surface of the sleeve forming the magnetic brush, and a device that is separated from the circumferential surface of the relay sleeve. A cleaning device for a photoconductor, comprising an electrode for applying an electric field to a magnetic carrier with toner and a toner collection roller, and returning the magnetic carrier from which toner has been removed to a sleeve of a magnetic brush device.