JPS6336344Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] The present invention relates to a cleaning device for a dry electrostatic printing device that efficiently removes residual toner remaining on a latent image drum after transfer with a simple configuration. It is.

In a dry electrostatic printing device, an optical or
An electrostatic latent image is formed by electrical means and visualized by adhering toner by magnetic brush development. Although this developed image is transferred to recording paper, it is well known that 100% of the image is not transferred, and some toner remains on the latent image drum.

This residual toner repeats over the surface of the latent image drum.
When used, it adheres to the recording paper again in the next transfer process, staining the printed matter and significantly deteriorating the resolution of the image.

Therefore, a cleaning device is generally provided to remove the residual toner from the surface of the latent image drum.

[Prior art]

A well-known method for removing this residual toner is to use a cylindrical bristle brush.

This consists of a cylindrical bristle brush made by pasting animal fur or artificial fur onto a cylindrical ball core.
The axis of the bristle brush and the latent image drum axis are parallel to each other, and the bristle brush is rotatably arranged so that a part of the bristle brush comes into contact with the surface of the latent image drum.

[Problem that the invention attempts to solve]

However, as printing speeds have increased, cleaning devices have also been required to be faster, but conventional devices have not been able to provide sufficient cleaning effects. increase contact time. In other words, this was compensated for by lengthening the cleaning time and increasing the effectiveness.

However, this method not only requires a complicated and large-sized apparatus, but also cannot be expected to be very effective.

[Means for solving problems]

In view of the above-mentioned conventional problems, the present invention provides a cleaning device for a dry electrostatic printing device that is equivalent in shape to a conventional cylindrical bristle brush and that can perform high-speed and highly efficient cleaning. This method involves developing an electrostatic latent image formed on a latent image drum having a photoconductive layer or a dielectric layer using a dry electrostatic developing device to form a toner image, and transferring the toner image onto recording paper. A cleaning device for a dry electrostatic printing device that later removes toner remaining on the latent image drum, which is installed at a position where it can come into contact with the surface of the latent image drum, and has a polarity of the same or opposite polarity as that of the residual toner. A brush made of a chargeable thread, a mesh electrode that applies an electric charge of the same polarity as the residual toner to the brush by frictional charging with the brush, and a contact portion between the brush and the mesh electrode in the moving direction of the brush. A cleaning device for a dry electrostatic printing device, characterized in that the cleaning device comprises means disposed on the latent image drum side for applying an electric charge having a polarity opposite to that of the residual toner to the brush.

[Effect]

In other words, in the past, there was a tendency to treat the surface of the bristles with surfactants to prevent tribo-electrification of the bristle brush from occurring, as it was thought that the tribo-electrification of the brush would interfere with cleaning. In our invention, we actively and effectively utilize this frictional charging, which charges the brush bristles to a potential of opposite polarity to the toner, and creates a Coulomb force that acts between this charge and the toner charge. The residual toner is adsorbed to the bristles and removed from the latent image drum, and the brush is charged to the same polarity as the toner by frictional charging in order to effectively remove the toner adhering to the brush.

In triboelectric charging, the amount of electricity, polarity, etc. of the charging are determined by the material, shape, surface condition, and speed of the two objects that are rubbing against each other, and by changing the combination of these, a desired charging state can be obtained.

For example, when a part of a cylindrical bristle brush is brought into contact with a grounded metal electrode and the brush is rotated, the bristle of the brush is charged by frictional charging. As an example, FIG. 1 shows the relationship between the number of rotations and the charging potential of a brush made of rayon and Teflon threads.

In the figure, the horizontal axis represents the number of brush rotations, and the vertical axis represents the charged potential of the bristles, where 1 is for rayon yarn and 2 is for Teflon yarn.

The charging characteristics are positive in the case of rayon-based materials and negative in the case of Teflon-based materials, and both exhibit a potential of several kilovolts (Kv). Therefore, the rayon type is effective when adsorbing negatively charged toner, and the Teflon type is effective when adsorbing positively charged toner.
It has a strong adsorption force due to Coulomb force, and is extremely effective in removing residual toner from the latent image drum at high speed and with high efficiency.

Instead of a grounded metal electrode, an organic or inorganic insulator can be used as the friction member.

As an example, the relationship between brush rotation speed and charging potential when an acrylic electrode and a rayon brush are rubbed is shown by curve 3 in FIG. That is, since the bristles of the brush are negatively charged, they are effective in suctioning and removing positively charged toner.

In the above-mentioned cleaning device, the shape of the ground metal electrode is a flat plate, a mesh, a wire, or a needle, and the material used is copper, copper, copper, stainless steel, or the like. Materials for the friction member made of insulators include organic materials such as acrylic, styrene, and Teflon, and inorganic materials such as glass and ceramics. Materials for the bristles that make up the brush include rayon, Teflon, vinylon, nylon, and silk. The cross-sectional shape may be round, square, circular, etc., and various modifications may be made to the shape, material, weave of the hair, and combinations thereof.

Corona discharge is generally used as a means for charging an insulator, but even when cleaning is performed by charging the bristles of a brush using this method, the same effect as the above-mentioned cleaning device can be obtained. In this case, since a charging corona discharge device is added, the cleaning device becomes somewhat complicated, but in this case, there is an advantage that the charging polarity and amount of charging of the brush can be easily controlled.

〔Example〕

Next, FIG. 2 shows some specific embodiments of the cleaning device for a dry electrostatic printing device according to the present invention.
This will be explained with reference to FIG.

FIG. 2 shows an example of the configuration of a cleaning device that applies frictional electrification between a grounded metal electrode and a brush.

In the figure, 4 is a cylindrical bristle brush consisting of a cylindrical core 4b and bristles 4a glued on the circumference of the cylindrical core;
6 is a mesh metal electrode for brush charging that also serves to scrape off toner adhering to the bristles 4a; 6 is a metal case that supports the mesh metal electrode 5 and is electrically connected to the mesh metal electrode 5 and grounded; be.

7 is an electrostatic latent image drum; 7' is residual toner that adheres to the surface of the electrostatic latent image drum 7 after the development and transfer process; 8 and 9 are electrostatic latent image drums 7, respectively.
and the rotation direction of the cylindrical bristle brush 4, 10
11 is an air suction port, and 11 is a friction member made of an insulator for charging the brush and provided at a position in contact with the cylindrical bristle brush 4. The friction member 11 is provided at a position before the cylindrical bristle brush 4 and the electrostatic latent image drum 7 come into contact, and the mesh metal electrode 5 is provided at a position after they come into contact.

As an example, if an acrylic insulator is used for the friction member 11 and the bristles 4a are made of rayon thread, the surface of the cylindrical bristle brush 4 will be negatively charged as shown by the curve 3 in FIG. The charged residual toner 7' can be adsorbed well.

Next, the operation will be explained.

First, it is assumed that the cylindrical bristle brush 4 is rotated in the direction of the arrow 8 shown in the figure, and its surface is rubbed by the friction member 11, so that the entire bristle brush 4 is negatively charged.

At this time, it is assumed that the residual toner 7' adhering to the surface of the electrostatic latent image drum is positively charged.

Next, the cylindrical bristle brush 4 whose surface is negatively charged contacts the electrostatic latent image drum 7, which is rotating in the direction of arrow 9 in the figure at a speed slower than the circumferential speed of the cylindrical bristle brush 4, and the residual toner 7' is removed. The toner 7' on the drum surface is caused by the Coulomb force acting between the electric charge of
is absorbed by the bristles 4a and removed from the drum surface 7.

The cylindrical bristle brush 4 is further rotated, and the bristle 4a on which the residual toner 7' is adsorbed is again guided to the mesh metal electrode 5.

The brush 4 on which the residual toner 7' has been adsorbed is rubbed against the net-like metal electrode 5, since the rayon thread is rubbed against the ground electrode and becomes positively charged as shown by the curve 1 in FIG. is residual toner 7'
Similarly, it is charged with positive polarity.

As a result, residual toner 7' adhering to the brush 4
acts to separate from the surface of the brush due to the repulsive force caused by the charged charge on the brush. At the same time, as the brush rotates, the bristles of the brush rub against the mesh metal electrode, effectively scraping off the toner. The scraped off residual toner 7' is guided to a toner recovery device (not shown) by suction air from the suction port 10.

The above operations are repeated continuously.

FIG. 3 shows an example of the configuration of a cleaning device in which a corona discharge device is used to apply charges to a brush for toner attraction.

Numbers in the figure are assigned corresponding to each part of the embodiment described above, and in the figure, 12 is electrically connected to the discharge wire electrode 12' and the metal case 6,
A corona discharge device consists of a ground electrode 12'', and 13 is a high voltage power source.

This embodiment is similar in principle to the embodiment shown in FIG. 2, and uses a corona discharge device 12 in place of the friction member 11 that applies a charge of opposite polarity to the toner shown in FIG. It performs a similar function. The operation and effect are almost the same as the embodiment shown in Fig. 2. However, in the case of this embodiment, a corona discharge device for brush charging is added, so the configuration of the device is slightly complicated; This has the advantage that the polarity and charge amount can be easily adjusted and controlled.

In each of the embodiments described above, the cylindrical bristle brush may be rotated in a direction opposite to that shown in the drawings. However, in this case, it is necessary to install the friction member 11 and the corona discharge device 12 on the lower side of the figure.

〔effect〕

As explained above, according to the present invention, even a high-speed dry electrostatic printing device can be cleaned in a short time.
The latent image drum can be sufficiently cleaned.

In addition, the toner attached to the brush is removed by contact with the mesh electrode, and the contact with the mesh electrode generates an electric charge of the same polarity as that of the toner on the brush, so that the residual toner adhering to the brush is removed. The brush is detached from the surface due to the repulsive force generated by the charged electric charge on the brush, so that the brush can be kept in a clean state at all times, and the replacement period of the brush can be extended.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the relationship between brush rotation speed and charging potential depending on the material of the brush, and FIGS. 2 and 3 are diagrams for explaining an embodiment of a cleaning device for a dry electrostatic printing device according to the present invention. This is a diagram for In the figure, 4 is a cylindrical bristle brush, 5 is a mesh metal electrode, 6 is a metal case, 7 is a latent image drum, and 11
1 is a friction member, 12 is a corona discharge device, and 13 is a high voltage power source.

Claims (1)

[Scope of utility model registration request] An electrostatic latent image formed on a latent image drum having a photoconductive layer or a dielectric layer is developed into a toner image using a dry electrostatic developing device, and after the toner image is transferred to recording paper, the latent image is A cleaning device for a dry electrostatic printing device that removes toner remaining on an image drum, the thread being provided at a position where it can come into contact with the surface of the latent image drum and capable of being charged to the same or opposite polarity as the remaining toner. a brush consisting of a brush, a mesh electrode that applies an electric charge of the same polarity as the residual toner to the brush by frictional charging with the brush; 1. A cleaning device for a dry electrostatic printing device, characterized in that the cleaning device comprises means for applying an electric charge to the brush with a polarity opposite to that of the residual toner.