JPS62254172A - Recovery roller device for magnetic brush cleaning - Google Patents

Abstract

PURPOSE:To obtain excellent cleaning performance on the whole even if paper sizes are changed by dividing a recovery roller axially and electrically almost to each size of transfer paper and applying mutually different voltages. CONSTITUTION:The recovery roller 11 is divided into parts 21a-21c, whose boundaries are insulated electrically; and the divided areas are applied with voltages according to respective sizes of transfer paper. Contactors 22a-22c are contactors for supplying the respective voltages and a controller 16 generates signals for the respective sizes to set the voltages of the respective parts to desired values. For example, when a copy of A4 size is taken, the parts 21a and 21b are held at the same voltage as a voltage applied to a brush sleeve 10 and when a copy of B4 size is taken, the part 21a is held at the same voltage with the sleeve. Consequently, an abnormal decrease in toner density is eliminated and the polarity inversion of toner is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a collection roller device for magnetic brush cleaning of electrophotographic recording devices such as electrophotographic copying machines, facsimiles, and printers.

(Prior art) In conventional magnetic brush cleaning, the same voltage is applied in the entire axial direction, so when making an A4 size copy, for example, there is no toner to be cleaned in parts 21a and 21b of the magnetic brush. However, since the collection roller is highly biased, the toner concentration is abnormally reduced, causing the carriers to rub against each other, making it easy to scrape off the coating film on the carrier surface, and preventing normal charging. In addition, if a small amount of toner remains in contact with the high bias of the collection roller for a long time, it will become reversely charged (because the polarity of the voltage applied to the collection roller is opposite to the charged polarity of the toner), it will be charged to the photoreceptor. The toner may stick again or the amount of charge will become low, and then when copying with wide paper (1), the image will deteriorate due to poor cleaning, and the toner will scatter from the edge of the cleaning unit and stain the inside of the machine. There was a problem.

(the purpose) The present invention aims to eliminate the above problems.

(Structure) The present invention has been made in view of the above-mentioned problems, and includes removing residual toner on a photoconductor using a magnetic brush, bringing a collection roller into contact with the magnetic brush, and applying voltage to the collection roller. In magnetic brush cleaning, which attracts and collects the toner in the magnetic brush, the collection roller is electrically divided in the axial direction into widths that are approximately the same as each size of transfer paper, making it possible to apply different voltages to each. It is characterized by this.

Hereinafter, a detailed explanation will be given based on the illustrated embodiment. FIG. 1 is an overall schematic diagram of an electrophotographic copying machine to which the present invention is applied. After the photoreceptor is uniformly charged by the primary charger 1, image exposure is performed by the exposure optical system 2, unnecessary charges are erased by the erase lamp 3, and then a toner image corresponding to the latent image is created by the developing device 4 and the transfer agent After the toner image is brought into close contact with the photoreceptor 8, a transfer charger 5 transfers the toner image onto the transfer agent, and a separation charger 6 separates the toner image from the photoreceptor.

The transfer agent 8 passes through the fixing device 7 to complete a copy image. Furthermore, the toner remaining on the photoreceptor is removed by a cleaning device 9.

The cleaning device 9 includes a magnetic brush sleeve 10, a collection roller 11, a collection blade 12, a discharge device 13, a power supply 14 for the magnetic brush sleeve, and a power supply 1 for the collection roller.
5, an applied voltage controller 16.

There are a plurality of fixed magnets inside the magnetic brush sleeve, which attract magnetic carriers to the surface to form a magnetic brush. Further, the toner is removed from the photoconductor by rubbing the surface while applying a voltage of opposite polarity to the toner using the power source 14. Further, the toner electrostatically attracted to the magnetic brush sleeve is attracted to a collection roller 11 to which a voltage higher than that of the magnetic brush sleeve is applied, scraped off by a blade 12, and discharged from the cleaning unit by a discharge device 13. Ru.

FIG. 3 shows a first embodiment of the collecting roller device of the present invention.

The collection roller 11 can freely rotate around a shaft 24 via a bearing 23. The gear 25 also transmits drive to the collection roller.

The collection roller 11 is divided into parts 21a, 21b, and 21c, and the boundaries of each part are electrically insulated. Further, as shown in FIG. 3, voltage can be applied to the divided areas according to the size of each transfer paper. 22a, 22b, and 22c are contacts that supply each voltage, and the controller 16 generates signals of each size to set the voltage of each part to a desired value.

For example, when making an A4 size copy, the voltage applied to the portions 21a and 21b is the same as the voltage applied to the magnetic brush sleeve 10,
In the case of B4 size, by making the part 21a the same as the sleeve voltage, it is possible to prevent an abnormal decrease in toner concentration and a reversal of toner polarity.

FIG. 4 shows the second embodiment, A4. B4. For A3, 31c, 31c and 31b, 31c, 31b and 31 respectively
It will look like a. The shaft 24 has a contact 32a.

32b and 33c are provided, and 31a, respectively.

A voltage from a power source 15 is applied to portions 31b and 32c that are in contact with the roller 11 from the inside. Further, the control device 16 controls which part of the collection roller 11 is to be applied with voltage.

(Effects) The present invention uses a magnetic brush that removes residual toner on a photoconductor using a magnetic brush, brings a collection roller into contact with the magnetic brush, and applies voltage to the collection roller to attract and collect the toner in the magnetic brush. During cleaning, the collection roller is electrically divided in the axial direction into widths that are approximately the same as the width of each size of transfer paper, and different voltages can be applied to each, which may partially shorten the life of the cleaning agent. Even if the paper size changes without any problems, good cleaning performance can be obtained across the board, and since the amount of toner in the cleaning agent can be maintained at an appropriate level, the characteristics of the carrier and toner can be maintained in a good condition.

[Brief explanation of drawings]

FIG. 1 is a general schematic diagram of an electrophotographic copying machine according to the present invention, FIG. 2 is a perspective view of the magnetic brush sleeve and collection roller of FIG. 1, and FIG. 3 is a front cross-sectional view of the first embodiment of the present invention. , FIG. 4 is a front sectional view of a second embodiment of the present invention. 10...Magnetic brush sleeve 11...Collection roller 15...Collection roller application power source 16...Control device 21a, 21b, 21c, 31a, 31b, 31cm Divided parts of collection roller

Claims (1)

[Claims] In magnetic brush cleaning, the residual toner on the photoreceptor is removed by a magnetic brush, a collection roller is brought into contact with the magnetic brush, and a voltage is applied to the collection roller to attract and collect the toner in the magnetic brush. A collecting roller device for magnetic brush cleaning, characterized in that it is electrically divided into widths approximately the same as the widths of each size of transfer paper in the axial direction, and different voltages can be applied to each.