JPS61198181A - Magnetic brush cleaning device - Google Patents

Abstract

PURPOSE:To improve cleaning effects by composing a magnetic brush cleaning device of a fiber member arranged at the upstream side of a magnetic brush forming means and an auxiliary cleaning means which has a magnet for producing a magnetic field between the fiber member and an image carrier. CONSTITUTION:A magnetic brush unit 3 serves as the magnetic brush forming means between a magnetic brush cleaning device and a developing device and a magnetic brush M performs image forming operation for development in copying operation and is applied with an AC bias in cleaning operation to remove remaining toner. The fiber member 13 is the auxiliary cleaning means and the magnet 15, fixed and arranged on the fiber member 13, establishes a magnetic field between the fiber member 13 and a photosensitive drum 7. When the photosensitive drum 7 enters the 2nd rotation, an electrostatic charger 1 is placed in a nonoperation state and the drum finishes the 2nd rotation after being cleaned with the magnetic brush.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to electrostatic recording devices such as electrophotographic copying machines. In particular, the present invention relates to an improvement in a magnetic brush cleaning device that uses a magnetic brush to clean an image bearing member in an electrostatic recording device to remove residual toner.

2. Description of the Related Art In the electrostatic recording device, for example, an electrophotographic copying machine, a magnetic roll, which is a magnetic plan forming means, is disposed opposite to a photosensitive drum, which is an image bearing member, and an AC bias is applied to the magnetic roll. A magnetic blanking device which removes residual toner adhering to a photoreceptor drum by rubbing a magnetic brush formed on a magnetic roller against the photoreceptor drum is disclosed in Japanese Patent Laid-Open No. 56-97370.
It is stated in the No.

Although the magnetic plan cleaning device can almost completely remove residual toner from a solid image, it has a problem in that it cannot completely remove residual toner that is concentrated in thin lines or etched areas of a flat image.

A magnetic brush cleaning device has been developed in which a fiber member made of a non-magnetic material is disposed on the upper side of the step (separate application filed by the applicant). Although it has a high cleaning effect and can almost completely remove residual toner from each part by erasing the edge effects of There is an opening point.

Purpose of the Invention As a result of intensive research aimed at resolving the above-mentioned inconvenience, the inventor of the present invention has found that during the printing operation, only one toner scatters on the fiber member and comes into contact with an image carrier such as a photoreceptor drum. We have found that when the toner is a magnetic material, the toner can be held in the fiber member and prevented from scattering by applying a magnetic field to the fiber member.

The present invention has been completed based on the above findings, and its purpose is to be able to remove residual toner even from fine lines and edge portions of Petter 1 images, and to prevent background fog from forming on images. The object of the present invention is to provide a magnetic brush cleaning device with excellent cleaning effects.

Structure of the Invention The structure of the present invention is that, in an f# electric recording apparatus having a magnetic brush cleaning device, a magnetic brush forming means, a means for applying an AC bias to the magnetic brush forming means, and a magnetic brush forming means are provided. This is a magnetic brush cleaning device characterized by comprising a fiber member disposed on the upper beach side and an auxiliary cleaning means having a magnet for forming a magnetic field between the fiber member and the image carrier.

The present invention was able to achieve the above object by being configured as described above.

Example The present invention will be explained in detail by way of examples.

1 is a schematic explanatory diagram of an electrophotographic copying machine for explaining the first embodiment of the present invention, and FIG. 2 is an enlarged view of the main part of FIG. 1.

The Mineko-Yomahinoki photographic machine shown in Fig. 1 has a charger 1. & Optical device 2.
Magnetic brush unit 3. Transfer device 41 separation device 5. Fuser6. Photosensitive drum 7, paper feed roller 8, fiber member 13. Magnet 15. It is equipped with an AC bias power supply V, etc., and the magnetic brush unit 3 serves as a magnetic brush forming means for both the magnetic plan cleaning device and the developing device, and forms an image while the photosensitive drum 7 rotates twice. It is operated as follows.

As shown in FIG. 2, the magnetic blur 7 unit 3 includes a magnetic roll consisting of a non-magnetic sleeve 9 and a magnetic core 10, and a dogta blade 12. Toner hopper 14. It is equipped with a housing 11, etc., and a toner hopper 1.
4 stores toner T. Further, the non-magnetic sleeve 9 of the magnetic roll is provided with an AC bias power source (2) so as to be able to apply an AC bias only to the cleaning pin. As mentioned above, the magnetic brush unit 3 serves as the magnetic brush cleaning device, the developing device It, and the magnetic brush forming means of 7, and the magnetic brush M formed on the magnetic roll is used for developing purposes during the copying operation. It performs image formation, and during cleaning operation, AC bias is applied to remove residual toner.

The fiber member 13 is an auxiliary cleaning means, and is provided so as to be able to rub the photoreceptor drum 7 with an appropriate pressing force, and is made of non-MS material, such as natural or synthetic fibers flocked in a brush shape, or These include things made into cloth. The contact width of the fiber member 13 with the photoreceptor drum 7 is preferably as wide as possible in the moving direction of the photoreceptor drum 7, or may be about 0.5 to 30 degrees.

The magnet 15 is attached to the [81
Although the fiber member 1 is fixedly placed on the fiber member 13, it may be placed in the vicinity of the fiber member 13. Note that the force of the magnetic field generated by the magnet 15 binds and burns a single toner on the fiber member, but if the strength of the magnetic field on the surface of the photoreceptor drum 70 is equal to or greater than 0.0 Gauss, the toner is scattered. It can be restrained within a 1:3 ratio on the fiber part side. Furthermore, in order to increase the force of the magnetic field generated by the magnet 15, it is desirable to distribute the power to the magnet 15 at a distance of 15 or less from the surface of the photoreceptor drum 70. The printing machine is constructed as described above, and is operated so as to form one image during two rotations of the photoreceptor drum. Copying is performed during the first rotation, and cleaning is performed during the second rotation. It will be done. That is,
At the 01st rotation of the photoreceptor drum, charging is performed by a charger], light is emitted by an exposure device 2, development is performed by a magnetic brush unit 3 which acts as a developing device without applying an AC bias, and transfer to a transfer paper P is performed by a transfer device 4. 2. Processes such as separation of the transfer paper P from the photoreceptor tram 7 by the separation device 115 are sequentially performed, and an image is formed. Transfer 7 separated by separation device 5
Ej and aP are sent to the fixing device 6 and subjected to fixing processing. on the other hand,
The photosensitive drum 7 completes its first rotation with untransferred toner (residual toner) attached thereto. When the photosensitive drum 7 enters its second rotation, the charger 1 is set to a non-operating state, and the magnetic brush unit 3 is applied with a bias C. When the photosensitive drum 7 rotates, the residual toner is first rubbed by the fiber member 13, and then by the magnetic brush of the magnetic brush unit 3, which acts as a magnetic brush cleaning device. When the toner is rubbed by the magnetic brush, the residual toner is attracted by the magnetic brush and removed from the photosensitive drum 7. After being cleaned by the magnetic brush as described above, the photosensitive drum 7 completes its second rotation. Then, it waits at the copy start position.

Thereafter, the copying operation and the cleaning operation are performed in the same manner, but the residual toner adhering to the photoreceptor drum 7 during the cleaning operation is first rubbed and moved by the fiber member 13, so that it is not removed from fine lines or edges of solid images. Any residual toner adhering to the area is also removed by the magnetic brush, and is almost completely removed. Further, although toner accumulates in the fiber member 13,
The toner is transferred to the fiber member 1 by the force of the magnetic field generated by the magnet 15.
Since the particles are confined within 3, unlike conventional ones, they do not scatter during the copying operation and cause background blur in the image.

In this embodiment, the magnetic brush forming means includes A.
C) <It is preferable to apply Ias, but it is preferable to apply D in the form of a pulse.
Other oscillating bias voltages such as C bias may be applied. Furthermore, it goes without saying that the image carrier may be belt-shaped instead of drum-shaped.

Effects of the Invention The magnetic brush cleaning device of the present invention includes a fiber member;
An auxiliary cleaning means having a magnet for forming a magnetic field between the fiber member and the image carrier is disposed upstream of the magnetic brush forming means provided to apply an AC bias. Before the residual toner adhering to the carrier is removed by the magnetic brush forming means, the etch effect can be erased by rubbing with the auxiliary cleaning means, so the residual toner adhering to fine lines or the edges of solid images can be almost completely removed. Can be removed. In addition, since the toner accumulated in the fiber member of the auxiliary cleaning means is restrained within the fiber member by the force of the magnetic field from the magnet, it is scattered during copying operation unlike conventional ones, causing the image to be distorted. Never.

As described above, the present invention was able to achieve the above object with the above configuration.

[Brief explanation of the drawing]

FIG. 1 is a detailed explanatory diagram of the present invention, and FIG. 2 is an enlarged view of the main part of FIG. 3...Magnetic brush unit. 7... Photosensitive drum, 9... Non-magnetic sleeve. 10... Magnet core, 13... Fiber member. 15...Magnet, M...Magnetic brush. ■...AC bias power supply.

Claims (3)

[Claims] (1) In an electrostatic recording device having a magnetic brush cleaning device, a magnetic brush forming means, a means for applying an AC bias to the magnetic brush forming means, a fiber member disposed upstream of the magnetic brush forming means, and A magnetic brush cleaning device comprising an auxiliary cleaning device having a magnet for forming a magnetic field between the fiber member and the image carrier. (2) The magnetic brush cleaning device according to claim 1, wherein the fiber member is made of fibers flocked in a brush shape. (3) The magnetic brush cleaning device according to claim 1 or 2, wherein the magnetic brush forming means also serves as a magnetic brush forming means of a developing device of an electrostatic recording device. .