JPS63202786A - Cleaning device for image forming device - Google Patents

Abstract

PURPOSE:To maintain a stable cleaning function for a long period without causing any deterioration in picture quality such as decreases in image density and visibility by supplying low-resistance powder to toner caught by a magnet roller successively. CONSTITUTION:Part of residual toner on a photosensitive body 1 is caught directly by the magnet roller and the remainder is scraped off by a cleaning blade 3 and caught by the roller 4. Then the low-resistance material of <=10OMEGAcm which consists of low-resistance toner, strontium titanate, conductive carriers, etc., is supplied from a container 7 to the upstream side of a cleaning device 2 through a supply roller 8 so that >=0.5% of the powder is mixed with the toner layer formed on the roller 4. The nonmagnetic sleeve 8b of the roller 8 is applied with a bias 9 obtained by superposing a direct current on an alternating current to select the powder and bias properly according to the polarity of the residual toner, thereby sticking the powder on the photosensitive body. Consequently, the mean potential of the toner layer on the roller 4 never decreases to destroy a photosensitive layer.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Aspects of the invention (industrial application field) This invention relates to image forming apparatuses that utilize an electrostatic recording process, such as cotton electrocopiers and printers, particularly cleaning apparatuses thereof. It is related to.

(Prior Art and Issues to be Solved) In a well-known image forming apparatus that repeats the process of transferring a transferable toner image formed on the surface of an image carrier onto a sheet-like transfer material such as paper, the image forming apparatus is Sufficient removal of residual toner on the surface of the carrier is extremely important in order to continuously obtain high quality images.

As a cleaning means for this purpose, cleaning blades have been widely used in the past because they are simple in construction, compact, and have excellent toner removal functions.
The residual toner contains various foreign substances such as fine paper dust generated from the paper used as the transfer material, precipitates such as rosin and talc, and corona products due to the presence of high-pressure parts. It is known that these foreign substances adhere to the image bearing member and cause deterioration of image quality, and furthermore, these foreign substances cannot be sufficiently removed by a cleaning blade.

For this purpose, foreign substances such as those mentioned above should be removed.

In a cleaning device for an image forming apparatus that uses magnetic toner, a magnetic roller is disposed therein to collect residual toner, and the surface of the fll carrier is rubbed and polished by the collected toner to remove foreign matter as described above. Some methods have been proposed to remove this, and have had some success.

However, on the other hand, magnetic toner has a resistance value of 10'
For this reason, the toner captured by the magnetic roller is caused by friction (
After 17 charges, the potential gradually rises, and when the charge V exceeds the resistance of the image carrier, a discharge occurs between the two, which destroys the photosensitive layer on the surface of the image carrier, creating pinholes.
As a result, black dots and white dots appear on the formed image, resulting in a significant loss of image quality.

The present invention has been made to deal with such a one-full situation, and even in a cleaning device that rubs and polishes an image bearing member with toner, it can be used constantly and stably without causing the above-mentioned drawbacks. It is an object of the present invention to provide a leaning device that provides a cleaning effect.

(2) Structure of the invention (technical means for solving the problem and its operation) In order to achieve the above object, the present invention provides an image forming apparatus using magnetic toner, in which residual toner collected on a magnetic roller In a cleaning device configured to rub and polish a traveling image carrier, a substance made of a substance having a lower resistance value than the toner used is placed on the upstream side of the cleaning device when viewed in the traveling direction of the image carrier. The present invention is characterized in that the low resistance powder is sequentially supplied to the toner collected by the magnetic roller in the cleaning device by supplying the powder to the image carrier.

With this configuration, the electric charge generated by the friction of the toner is maintained at a low potential as a whole due to the presence of the powder, thereby preventing dielectric breakdown from occurring in the image carrier photoreceptor due to an increase in the amount of electric charge. be able to.

(Explanation of the Embodiment) Figure 1 of the attached drawings is a side view of the main parts of an embodiment in which the unreleased IJI is applied to a copying machine equipped with a rotating cylindrical photoreceptor. A cleaning device 2 is disposed close to and parallel to the photoreceptor l rotating in the direction of the arrow.

Incidentally, it goes without saying that a negative charger, an image signal applying means, a developing device, a transfer charger, and other members necessary for image formation are arranged around the photoreceptor, but these are not covered by the present invention. Since they are not directly related, they are all omitted.

Inside the cleaning device 212, a cleaning blade 3 is installed.
is arranged, one edge of which comes into pressure contact with the photoreceptor to scrape off the residual toner.

In the cleaning device, a Macnet roller 4 that rotates in the direction of the arrow shown in the figure is disposed on the upstream side of the cleaning blade when viewed in the traveling direction of the photoreceptor. Residual toner remaining on the photoconductor at the transfer site without contributing to the transfer reaches the cleaning device as the photoconductor rotates, and some of it is directly captured by the magnet roller, while the rest is scraped off by the blade 3 and then removed. It is captured by the magnetic force of the magnet roller.

These captured toners stand in spikes on the surface of the magnet roller, are cut by peracid by the spike cutting blade 6, reach a position close to the photoreceptor, and rub the surface thereof.

At this time, the excess toner cut by the blade 6 reaches a toner storage section within the cleaning device, and is further discharged to the outside by the conveyance screw 5 as necessary.

In such a device, in the present invention, the photoreceptor l
1 on the upstream side of the cleaning device 2 when viewed in the running direction of the cleaning device 2.
A container 7 containing powder made of a low-resistance substance such as toner, strontium titanate, or a conductive carrier, which has a resistance lower than the toner used for image formation and has a resistance of about 0I2Ωcm or less, is provided, and is then applied to the photoreceptor. By supplying an appropriate amount of low-resistance powder, the toner layer formed on the magnet roller 4 in the cleaning device contains 0.5% or more of the powder.
It is configured so that L is mixed in.

As shown in the figure, the container 7 has an open end facing the photoreceptor, and a magnet roller 8a is attached to this part.
A replenishment roller 8 consisting of a non-magnetic sleeve 8b covering the replenishment roller 8 is disposed, and by rotating one or both of these, the low resistance powder layer formed on the sleeve surface is sequentially moved, and the blade 7a is At the same time, the powder is triboelectrically charged. It is desirable that the powder be selected to be charged to a polarity opposite to that of the toner used for image formation.

A bias 9 in which alternating current and direct current are superimposed is applied to the sleeve, and depending on the potential near this position of the photoreceptor (usually Ov in the non-image area) and the polarity of the residual toner,
By appropriately selecting low resistance powder and bias,
The powder can be attached to the photoreceptor by suction.

Is the powder that adheres to the photoconductor cleaned in this way along with the residual toner? At step tff12, a toner layer is formed together with the toner on the surface of the magnet roller 4, and the surface of the photoreceptor 1 is rubbed and polished to remove various foreign substances as described above.

With this structure, even if the amount of charge on the toner increases, the average potential of the toner layer on the magnetic roller decreases due to the presence of the low-resistance powder, and further,
Powder is sequentially supplied from the container 7 mentioned above, and excess toner is removed by the blade 6, so that the toner that forms the toner layer on the surface of the magnet roller is also sequentially replaced. Charge 71 does not increase enough to destroy the layer.

As explained above, in a cleaning device configured to form a magnetic toner layer on a magnetic roller and rub the photosensitive layer on the surface of an image carrier, a low-resistance powder serving as an antistatic agent for the toner is applied to the toner. Since this is done after the toner has been used for image formation, there is no risk of image quality deterioration such as a drop in image density, and the amount of powder supplied can be freely changed according to the situation. The abrasive action can be controlled once again.

FIGS. 2 and 3 show other embodiments of the present invention, and the basic configuration of the cleaning device is not particularly different from that described above, and corresponding parts are designated by the same reference numerals. are shown, and their explanation will be omitted.

In the one shown in Fig. 2, the ear cutting blade 6 is
In the case shown in FIG. 3, a bias having a polarity opposite to that of the toner is applied to the blade 6.

With this configuration, the toner charge is released to the ground through the low-resistance powder, or it is charged to the opposite polarity to the toner and neutralized with the toner charge, thereby preventing toner charge-up. Blocking can be accomplished more reliably.

The device shown in FIG. 4 has a magnet roller 4a covered with a conductive sleeve 4b made of a non-magnetic material instead of the magnet roller 4 in the device shown in FIG. 1, and can be used as a cleaning device. There is no particular difference in the basic structure and operation from that shown in Figure 1.

With such a configuration, the charge of the low-resistance powder can be received by the large-capacity sleeve, thereby promoting a reduction in the amount of charge on the toner layer.

FIGS. 5 and 6 show still other embodiments, [-
In the apparatus shown in FIG. 4, the sleeve 4b is shown in one case where it is grounded, and in the other case where the sleeve 4b is biased in the opposite polarity to that of the toner.

With such a configuration, it is possible to more effectively suppress toner charge-up, as shown in FIGS. 2 and 3 above.

Although the present invention has been described above with respect to a case where it is applied to a copying machine, it will be easily understood that the present invention is not limited to this and can be applied to other image forming apparatuses.

(3) Effects of the Invention Since the present invention has the configuration described above, the increase in the electric charge of the toner rubbing on the surface of the image bearing member can be prevented by using an extremely simple configuration, completely unrelated to image formation using the toner. It is possible to reliably prevent damage to the surface of the image carrier and the surface photosensitive layer, and it is possible to maintain a stable cleaning function over a long period of time without causing deterioration of image quality such as a decrease in image density or clarity, and to obtain high-quality images. It greatly contributes to

[Brief explanation of the drawing]

FIG. 1 is a side view of essential parts of an embodiment of a cleaning device according to the present invention, and FIGS. 2 to 6 are side views showing other embodiments, respectively. 1. Working photoreceptor, 2. Fist cleaning device, 311.
・Cleaning blade, 4/6 tatami magnetic roller,
4b... Conductive sleeve, 6... Working ear cutting blade,
7...Low resistance powder container, 8...Low resistance powder supply roller. Kotobuki 1

Claims (6)

[Claims] (1) In a cleaning device that includes a traveling image carrier and a magnet roller that is disposed close to the image carrier and captures residual magnetic toner inside the cleaning device, a cleaning device is provided that is arranged on the upstream side of the magnet roller when viewed in the running direction of the image carrier. . A cleaning device comprising means for supplying low resistance powder having a resistance value lower than that of the magnetic toner to the image carrier. (2) The resistance value of the powder mixed in the toner is 10^1^2
The cleaning device according to claim 1, wherein the cleaning device is made of a substance having a resistance of Ωcm or less. (3) The cleaning device according to claim 1, wherein the amount of low resistance powder mixed in the toner layer on the surface of the magnet roller is 0.5% or more of the toner. (4) A cleaning device according to any one of claims 1 to 3, wherein the magnet roller is covered with a conductive sleeve. (5) The cleaning device according to claim 4, wherein the conductive sleeve is grounded. (6) The cleaning device according to claim 4, wherein a bias having a polarity opposite to that of the toner is applied to the conductive sleeve.