JPH0640960U - Contact charging device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a contact charging device that removes all toner attached to the tips of conductive brushes and does not scatter the removed toner to peripheral devices. In the vicinity of the photosensitive drum 1, a charging brush 3 in which a large number of conductive fiber bristles are planted on a surface of a shaft formed of a conductive material in a cylindrical shape is rotatably supported.
The tips of the hairs are always in contact with the surface of the photosensitive drum 1. On the upper part of the charging brush 3, a magnet 12 formed on a cylinder is rotatably arranged in parallel with the charging brush 3 at a position where it contacts the tips of the charging brush 3. This magnet 12
Attracts the magnetic toner remaining on the surface of the photoconductor drum 1 without being scraped off by the cleaner blade 11 and adhering to the bristles of the charging brush 3.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a contact charging device used in an electrophotographic device.

[0002]

[Prior art]

 Conventionally, an electrophotographic apparatus is equipped with a charging device for uniformly charging the surface of the photosensitive drum to a predetermined potential. As this charging device, a corona discharger mainly composed of a wire electrode and a shield electrode called a scorotron is mainly used. This corona discharger has long been adopted as a device that can achieve uniform charging with relatively simple control, and is still used in many electrophotographic devices.

However, This corona discharger produces ozone during discharge, but this ozone has a harmful effect on the human body. Therefore, the electrophotographic apparatus always requires a fan that generates an ozone absorption / decomposition filter and an air flow toward the filter. Therefore, it has been impossible to reduce the size and cost of the electrophotographic apparatus. In addition, foreign matter such as toner and silicon compound adheres to the discharge wire, which not only has a great adverse effect on image quality, but also requires cleaning treatment of the adhered foreign matter.

Therefore, recently, it has been proposed to use a contact charging device instead of the corona discharger, which has many problems as described above. In this contact charging device, for example, a predetermined DC voltage is externally applied to a cylindrical conductive fiber bristle brush as described in JP-A-57-46265, and while rotating this brush. By directly contacting the surface of the image carrier with a predetermined pressure contact force, charges are directly injected into the surface of the image carrier to uniformly charge the surface of the image carrier at a predetermined potential.

[0005]

[Problems to be solved by the device]

 However, in the above contact charging device, the brush must be brought into direct contact with the image carrier in order to charge the image carrier, so that there is a particular problem that a non-contact type charger such as a corona discharger does not have. Occurs.

For example, in the electrophotographic apparatus, a portion of which is shown in FIG. 2, electrostatically generated by laser light generated by the laser generation means 25 on the surface of the photoconductor drum 21 rotated by the motor 22. A latent image is created, toner is attached to the electrostatic latent image by the developing device 27 to form a toner image, and then the toner image is transferred to the paper by the transfer device 28, but all the toner is transferred to the paper. Instead, some toner remains on the surface of the photosensitive drum 21. After that, the remaining toner is scraped off by a rubber member called a cleaner blade 29 which is in contact with the photoconductor drum 21, but the toner remains on the photoconductor drum 21 in a slight amount.

The minute residual toner moves with the rotation of the photosensitive drum 21, and comes into contact with the rotating charging brush 23. The toner remaining on the photosensitive drum 1 is scraped off by the rotating charging brush 23, and scattered around the photosensitive drum 21 and the charging brush 23. The toner scattered on the periphery again adheres to the photosensitive drum 21 and causes deterioration of the quality of the output image. Further, the scraped toner adheres to the tips of the charging brush 23 and causes one of the charging failures, which causes deterioration of the quality of the output image.

Therefore, in order to prevent the toner from sticking to the tips of the charging brush 23, a bar called a flicker bar 32 is provided in parallel with the charging brush 23 so as to come into contact with the tips of the charging brush 23. It has also been attempted to strike off the toner from the bristle tips by bringing the bristle tips of the charging brush 23 into contact with the flicker bar 32 as the charging brush 23 rotates.

However, although the flicker bar 32 can prevent the toner from sticking to the hair tips of the charging brush 23, the adhered toner is scattered around the charging brush 23, and the toner scattered around the periphery is scattered. It adheres to the photosensitive drum 21 again and causes deterioration of the quality of the output image.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to remove all the toner attached to the tips of the conductive brush and to scatter the removed toner to peripheral devices. It is an object of the present invention to provide a contact charging device.

[0011]

[Means for Solving the Problems]

 In order to achieve this object, the contact charging device of the present invention has a magnetic member disposed in the vicinity of the conductive brush roller which is in constant contact with the conductive brush roller.

[0012]

[Action]

 In the contact charging device of the present invention having the above structure, the magnetic material is always in contact with the conductive brush roller to adsorb the toner adhering to the conductive brush roller, and the toner remains on the conductive brush roller. And prevent toner from scattering.

[0013]

【Example】

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

The present embodiment is a laser printer which is a kind of electrophotographic apparatus, and FIG. 1 is a sectional view showing a part of the internal configuration of the laser printer.

At the center of the inside of the laser printer, a photosensitive drum 1 which constitutes the member to be charged of the present invention is arranged, and the photosensitive drum 1 has a gear 1a fixed to its end on a main motor (not shown). It meshes with two connected gears, and rotates in the clockwise direction in FIG. 1 when the motor rotates.

In the vicinity of the photosensitive drum 1, a charging brush 3 in which a large number of conductive fiber bristles are planted on the surface of a cylindrical shaft formed of a conductive material is rotatably supported. The hair tips are always in contact with the surface of the photosensitive drum 1. A gear 3a is fixed to one end of the charging brush 3, and the gear 3a meshes with the gear 1a of the photosensitive drum 1 via an idle gear 4. Therefore, the charging brush 3 rotates in the same direction as the photosensitive drum 1. The shaft of the charging brush 3 is grounded via a voltage application source 5, and a predetermined voltage is applied to the charging brush 3 by the voltage application source 5. Then, by the rotation of the charging brush 3, the tips of the brushes rub against the surface of the photosensitive drum 1, and the surface of the photosensitive drum 1 is uniformly negatively charged.

A laser beam generator 6 is arranged on the upper right side of the photosensitive drum 1, and the laser beam output from the laser beam generator 6 is reflected by a mirror 6 a and is reflected on the surface of the photosensitive drum 1. It is irradiated and forms an electrostatic latent image on the photosensitive drum 1.

On the right side of the photosensitive drum 1, a magnetic toner and a developing device 8 having a developing roller 7 for conveying the magnetic toner to the surface of the photosensitive drum 1 are provided. The magnetic toner is conveyed to the surface of the photosensitive drum 1 by the rotation of the developing roller 7, and adheres to the electrostatic latent image. That is, the electrostatic latent image is developed by the developing device 8 into a toner image.

A transfer corotron 9 is disposed below the photoconductor drum 1 with a predetermined space therebetween, and a sheet is conveyed between the photoconductor drum 1 and the transfer corotron 9. Then, the transfer corotron 9 is discharged, so that the toner image on the photosensitive drum 1 is transferred onto the sheet.

A cleaner box 10 is disposed on the left side of the photosensitive drum 1, and a cleaner blade 11 whose tip contacts the surface of the photosensitive drum 1 is disposed in the cleaner box 10. The magnetic toner remaining on the photosensitive drum 1 without being transferred is scraped off by the cleaner blade 11 and stored in the cleaner box 10.

On the upper part of the charging brush 3, a magnet 12 formed on a cylinder is rotatably arranged in parallel with the charging brush 3 at a position in contact with the tips of the charging brush 3. The magnet 12 remains on the surface of the photosensitive drum 1 without being scraped off by the cleaner blade 11, and adsorbs the magnetic toner attached to the tips of the charging brush 3. Further, since the magnet 12 is rotatably supported, it rotates counterclockwise in FIG. 1 as the rotary brush 3 rotates. The magnet 12 constitutes the magnetic member of the present invention.

The operation of the electrophotographic apparatus configured as above will be described.

The photosensitive drum 1 is rotated in the clockwise direction in FIG. 1 by the motor, and the charging brush 3 is also rotated in the rotational direction in FIG. 1, so that the photosensitive drum 1 is uniformly negatively charged. In this state, laser light is generated from the laser generator 5 based on print data input from an external device such as a computer, and an electrostatic latent image is formed on the photosensitive drum 1.

This electrostatic latent image is converted into a toner image by the developing device 8, and this toner image is transferred by the transfer corotron 9 onto the sheet conveyed between the photosensitive drum 1 and the transfer corotron 9. The sheet on which the toner image is transferred is conveyed to a thermal fixing device (not shown), and the toner image is fused and fixed on the sheet by the thermal fixing device.

The magnetic toner remaining on the surface of the photosensitive drum 1 without being transferred onto the paper by the transfer corotron 9 is scraped off by the cleaner blade 11 and stored in the cleaner box 10. The magnetic toner that is not scraped off by the cleaner blade 11 and remains on the surface of the photosensitive drum 1 moves as the photosensitive drum 1 rotates, is scraped off by the charging brush 3, and comes into contact with and adheres to the tips of the brushes. . The magnetic toner attached to the bristles moves as the charging brush 3 rotates, contacts the magnet 12, and is attracted to the magnet 12.

As described above, in the electrophotographic apparatus of the present invention, the magnetic toner remaining on the surface of the photoconductor drum 1 without being transferred to the sheet by the transfer unit 8 is scraped off by the cleaner blade 11 to be cleaned by the cleaner box. The magnetic toner, which is stored in 10 and remains on the surface of the photosensitive drum 1 without being scraped off by the cleaner blade 11, is scraped off by the charging brush 3 and adheres to the bristle tips of the charging brush 3, and then the magnet. Adsorbed on 12.

Therefore, no magnetic toner remains on the photosensitive drum 1, and the quality of the image to be printed next does not deteriorate. In addition, the magnetic toner does not adhere to the tips of the charging brush 3 and charging failure does not occur.

Further, since the magnet 12 is rotatably supported and is in constant contact with the tips of the charging brush 3, the magnet 12 rotates in the counterclockwise direction in FIG. The magnetic toner is evenly attracted to the outer circumference of the magnet 12 without being concentrated in one place.

Further, since the magnet 12 can be used any number of times by removing the attracted magnetic toner, for example, if the producer of the electrophotographic apparatus collects the magnet 12 and cleans the attracted magnetic toner. , Can be reused.

It goes without saying that the present invention can be applied to printers, copiers and facsimile machines using electrophotography other than laser printers.

[0031]

[Effect of device]

 As is clear from the above description, the contact charging device of the present invention removes all the toner attached to the tips of the conductive brush, and does not scatter the removed toner to peripheral devices. In addition, no charging failure will occur.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a part of an internal configuration of a laser printer.

FIG. 2 is a sectional view showing a part of a conventional electrophotographic apparatus.

[Explanation of symbols]

 1 Photoconductor drum 3 Charging brush 11 Magnet

Claims (1)

[Scope of utility model registration request] 1. A contact charging device for charging an electrically conductive brush roller, which is applied with a voltage from the outside, with an object to be charged, in the vicinity of the electrically conductive brush roller and always in contact with the electrically conductive brush roller. A contact charging device comprising a magnetic member.