JPH01284888A - Electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To prevent the image flow of an amorphous silicon photosensitive body by providing a magnetic sensor for detecting magnetic permeability in a cleaning device. CONSTITUTION:When residual toner remaining on the surface of the amorphous silicon photosensitive body 1 arrives at the position of a magnet roller 7b, it is loosened out from the surface with a magnetic brush so as to collect magnetism. Said toner is scraped with a napping regulating plate 7d and sliding and rubbing is performed on the surface. Then it is scraped with a cleaning blade 7a and carried to a discharged toner case with a carrier screw 9. In such a stage, the magnetic permeability is detected by the magnetic sensor 7c arranged in the cleaning device 7. When it is equal to or below the magnetic permeability necessary for forming the magnetic brush, magnetic toner is supplied from a developing device 4b through the photosensitive body 1.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrophotographic device using an amorphous silicon photoreceptor, and more specifically, an electrophotographic device that uses an electrostatic recording process, such as an electrostatic copying machine or a printer. an image forming device that
In particular, the present invention relates to an improvement in a cleaning device for both magnetic toner and non-magnetic toner to prevent image deletion.

[Prior Art] Conventionally, a transfer material on a sheet such as paper is brought into contact with a transferable toner image formed on the surface of an image carrier, and the toner image is electrostatically transferred to the transfer material. An image forming apparatus is known that repeats the process of separating this transfer material from an image carrier and removing residual toner that does not contribute to transfer and remains on the surface of the image carrier using an appropriate cleaning means such as a cleaning blade. ing. In particular, amorphous silicon photoreceptors have high surface hardness and are suitable for semiconductor lasers (77
It exhibits high sensitivity to long-wavelength light such as 0 nm to 800 nm), and shows almost no deterioration due to repeated use, making it particularly useful for high-speed copying machines and LBP (laser printers).
It has been praised as a photoreceptor for electrophotography such as beam printers.

In addition, in order to obtain a black image like that of ordinary documents,
One-component magnetic developer is widely used as a developer, and such a developer is equipped with a magnetic roller as a cleaning means, and the toner collected in the cleaning device is captured by the roller. The ozone particles are collected together to form a magnetic brush, and as a means of evenly polishing and removing ozone products that become sensitive to humidity and absorb moisture through repeated use, causing image defects such as image blurring. The aim is to maintain good leaning properties without increasing the frictional resistance of the photoreceptor.

[Problem to be solved by the invention] However, in recent years, not only black but also red,
As images in various colors such as blue are required, image forming apparatuses are also equipped with multiple developing devices each containing a developer with different characteristics. It has been proposed that the toner can be freely and easily selected from the above-mentioned black developer.

In such cases, this type of color toner is generally non-magnetic, so as mentioned above, in a device that uses a magnetic roller as a cleaning means, it is natural that the magnetic brush should not have such non-magnetic properties. Magnetic toner will also be taken in.

For this reason, when an image is formed with color toner, that is, non-magnetic toner, for a long period of time, this toner is not magnetically restrained by the magnetic roller, and on the other hand, the magnetic brush that has already been formed is also connected to the image carrier. Since it is inevitable that it will be gradually destroyed and deformed by mechanical action such as rubbing, the polishing effect of the magnetic brush will decrease, and image defects will occur due to the collected non-magnetic toner dripping onto the transfer material. Furthermore, there is a risk that this toner may cause problems such as contamination of various parts within the apparatus.

In order to avoid such a situation, firstly, without supplying a transfer material, the surface of the image carrier is coated with magnetic toner in the same manner as in normal development, and 5 to 10% of the normal transfer residual toner is coated. A method in which double the amount of magnetic toner is sent to a cleaning device and used to form a magnetic brush on a magnetic roller in the device.Secondly, a method in which spherical magnetic particles are mixed with toner and attached to a magnetic roller in the device. A method of forming a magnetic brush by using a magnetic brush has been proposed.

However, in the first method, the toner originally used for image formation is consumed without being involved in image formation.
Even if various copy usage modes are assumed, it is difficult to adequately handle the situation, and feeding the paper to a cleaning device unnecessarily increases the copying cost for the user. Furthermore, the second method also has a problem in that, after long-term use, the spherical magnetic particles are washed away by the collected toner and flow into the waste toner container, requiring occasional replenishment.

The present invention attempts to solve these problems. That is, an object of the present invention is to provide an electrophotographic apparatus that can prevent image deletion on an amorphous silicon photoreceptor and perform stable cleaning using both magnetic toner and non-magnetic toner.

[Means for Solving the Problems] In order to achieve the above object, the electrophotographic apparatus of the present invention has the following features:
In an image forming apparatus that uses an amorphous silicon photoconductor and is equipped with a developing device that uses magnetic toner, a developing device that uses non-magnetic toner, and a magnetic roller as a cleaning means, a magnetic roller that is installed in the cleaner and that detects magnetic permeability is used. Equipped with a sensor, the collected toner can be kept at a certain spike formation level! It is assumed that there are few means to maintain the 1ift rate. In addition, as means for maintaining the magnetic permeability, preferably, when the transfer material is not supplied, magnetic toner is delivered to a magnet roller via a photoreceptor and deposited, or spherical magnetic toner with a particle size of 30 to 200 μm is sent from a hopper to a magnetic roller. The particles are fed and deposited on the magnetic roller.

[Function] According to the present invention, since a magnetic sensor for detecting magnetic permeability is provided in the cleaner and a means for maintaining the magnetic permeability of the collected toner at a certain level of spike formation, the transfer material can be supplied. In the same way as normal development, the surface of the image carrier is coated with magnetic toner, and this is sent to a cleaning device, or spherical magnetic particles are sent and deposited on a magnet roller in the device, etc. It is possible to maintain the magnetic permeability of the collected toner at a constant spike formation level with high precision, and to clean both magnetic toner and non-magnetic toner well.

[Embodiment] FIG. 1 shows a first embodiment of the invention, and FIG. 2 shows a second embodiment of the invention.

In FIGS. 1 and 2, 1 is an amorphous silicon photoreceptor, 2 is a main charger, 3 is an image information providing means, and 4a
, 4b is a developing device, 5 is a transfer charger, 6 is a separation means, 7 is a cleaning device, 7a is a cleaning blade, 7b
is a magnet roller, 7c is a magnetic sensor, 7d is a stand-up regulating plate, 7e is a collecting brush, 8 is a static eliminating light source, and 9 is a conveyance section. Further, in FIG. 2, 7f is a hopper, and 7g is a replenishing means.

To explain further, around the cylindrical amorphous silicon photoreceptor 1 rotating in the direction of arrow A and perpendicular to the plane of the paper, a photosensitive layer on the surface of the photoreceptor is uniformly charged in the vicinity of the photoreceptor 1. A main charger 2, an image information imparting means 3 for forming an electrostatic latent image, a developing device 4a containing non-magnetic color toner for visualizing the latent image, a developing device 4b containing magnetic black toner, and a developing device 4b containing magnetic black toner. A transfer charger 5 for transferring a developed image onto a transfer material, a separating means 6 for separating the transfer material from the photoreceptor 1, a cleaning station 7, and a static elimination light source 8 are arranged in parallel.

Further, in the cleaning device, one edge of a cleaning blade 7a made of a suitable elastic material such as urethane rubber is in pressure contact with the photoreceptor 1 on the upstream side of the rotation. A magnet roller 7b that rotates in the opposite direction (direction of arrow B) to the photoconductor 1 is arranged at the contact position (0,5 to 2++v), and remains on the surface of the photoconductor 1 without contributing to the transfer at the transfer site. When the residual toner reaches the position of the magnetic roller 7b, it is loosened from the surface by a magnetic brush, and in the case of magnetic toner, a part of it is magnetically captured, scraped off by the spike regulating plate 7d, and then removed from the surface of the magnetic roller 7b. The toner toner is rubbed, then scraped off by the blade 7a, and transported to the waste toner case by the transport screw. During this process, magnetic permeability is detected by a magnetic sensor 7c disposed near the magnet roller 7b, and if the magnetic permeability is below the level required for forming a magnetic brush, the magnetic toner is removed from the developer 4b and the photoreceptor 1 is removed. The formation of a brush is ensured by feeding the spherical magnetic particles through a hopper 7f (see FIG. 2) containing the spherical magnetic particles (see FIG. 2). Further, a minute amount of submicron particles that have passed through the cleaning blade 7a are collected by a collection brush 7e made of acrylic nylon or the like. Next, the charge is removed by the charge removal light from the charge removal light source 8, and the process proceeds to the next time.

[Experimental Example 1] In the apparatus shown in Fig. 1, the diameter of the photoreceptor 1 is 108 m1I.
+1 process speed is 340 mm/sec.

The photoreceptor 1 used was one in which a 27 μm thick amorphous silicon photosensitive layer was deposited on an aluminum cylinder.

First, when color copying is performed continuously using the developing device 4a, the non-magnetic toner remaining after transfer is initially dripped off by the magnetic brush rotating in the same direction as the photoreceptor 1 at the magnet roller 7b. The toner is sent inside the cleaner and sent to the waste toner case by the conveying screw, and is cleaned well. However, if copying is continued as it is, as the collected toner is scraped off by the spike regulating plate 7d, the magnetic toner is removed. ratio decreases, the brush formation also becomes smaller, and the non-magnetic color toner scraped off by the blade 7a falls directly into the conveyance section 9,
It will stain the copy.

In this state, a coil is placed near the magnet roller 7b as the magnetic sensor 7C, and the change in magnetic permeability is detected as a change in the impedance of the coil. The device was operated to feed and deposit onto the magnet roller 7b.

With the above configuration, when 1000 A4 sheets were continuously copied using a non-magnetic color toner developing device, there was no toner dripping and a fairly good cleaning was achieved. Further, the amount of toner consumed to ensure the standing of the ears was about 50 g.

[Experimental Example 2] In the apparatus shown in FIG. 2, the same photoreceptor 1 as in Experimental Example 1 was used.

Further, as means for controlling magnetic permeability using the magnetic sensor 7C, the device was operated to directly supply magnetic particles from a hopper 7f for spherical magnetic particles provided on the top of the cleaner via a replenishing means 7g.

As magnetic particles are used for scrubbing, well-known amorphous or flat shaped particles are used to form a brush.When a brush is formed, mechanical bonding action between the particles is added, and the brush forming force is strong, so it is difficult to expose to light. Since the abrasive action is too strong when the photosensitive layer on the surface of the body 1 is rubbed, a spherical one is preferable. Furthermore, if the particles are smaller than 30μ, the particles that have left the brush portion during scrubbing will pass through the cleaning blade 7a, which is undesirable; if the particles are larger than 200μ, they will remain at the edge of the blade 7a. Since this may damage the surface and cause poor cleaning, the thickness is preferably 30 to 200 microns, and preferably 60 to 100 microns.

With the above configuration, when 1000 A4 sheets were continuously copied using a non-magnetic color toner intensifier, there was no toner dripping and a fairly good cleaning was achieved.

[Experimental Example 3] A copying machine having the configuration of Experimental Example 1 was heated at 32.5°C and 85% R.
Under the H environment, 1,000 consecutive A4 sheets were alternately copied using a magnetic black toner developer and a non-magnetic color toner developer, and 6,000 sheets per day were copied for one week, but no image deletion occurred.

[Experimental Example 4] A copying machine having the configuration of Experimental Example 2 was heated at 32.5°C and 85% R.
Under the environment of 1 (1), I alternately copied 1000 consecutive A4 sheets at a time using a magnetic black toner developer and a non-magnetic color toner developer, and continued to copy 6000 sheets a day for 1 week, but no image deletion occurred. [Comparative Example 1] The same evaluation as in Experimental Example 1 was conducted with the automatic magnetic toner feeding operation stopped.
After the 600th sheet, color toner dripping started to occur.
A good image was not obtained.

[Comparative Example 2] With the automatic magnetic toner feeding operation of Experimental Example 1 stopped, approximately 1 g of non-magnetic toner was added for every 10 copies.
When the same evaluation as in Experimental Example 1 was carried out by feeding magnetic toner as a black band, it was found that there was no toner smearing and a good level of leaning was achieved.

However, about 100 g of magnetic toner was consumed.

This is double the amount of the example, and 1000 yen of the office copy.
Equivalent to more than 1 sheet.

[Comparative Example 3] With the automatic feeding of magnetic toner in Experimental Example 1 stopped, approximately 1 g of magnetic toner was separately fed as a black belt for every 50 non-magnetic toner copies, and the experiment example When the same evaluation as in 1 was carried out, color toner smearing started to occur in rare cases from the 600th sheet, and good images could not be obtained.

This means that even if the same amount of magnetic toner as in Experimental Example 1 is fed,
This is thought to be due to poor matching between the interval of every 50 sheets and the feeding amount.

[Comparative Example 4] A copying machine having the configuration of Comparative Example 1 was heated at 32.5°C and 85% R.
In an environment of
After printing 6,000 sheets a day for one week, slight image blurring occurred at the edge of the magnetic roller on the third day.

[Effects of the Invention] As explained above, according to the present invention, a magnetic sensor for detecting magnetic permeability is provided in the cleaner, and a means for maintaining the magnetic permeability of the collected toner at a certain level of spike formation is provided. Therefore, without supplying transfer material, the surface of the image carrier is coated with magnetic toner and sent to a cleaning device in the same way as in normal development, or a spherical magnetic toner is coated on a magnetic roller in the device. The collected toner can be kept at a certain level of magnetic permeability to form spikes with high accuracy by feeding and depositing particles, and both magnetic toner and non-magnetic toner can be cleaned well. Therefore, it is possible to effectively and economically prevent image deletion on an amorphous silicon photoreceptor through a stable polishing effect.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional front view showing the first embodiment of the present invention, and the second embodiment is a cross-sectional front view showing the first embodiment of the present invention.
The figure is also a sectional front view showing the second embodiment. 1...Amorphous silicon photoreceptor 4a...Developer 4b containing non-magnetic color toner.
...Developer 7 containing magnetic black toner...Cleaning device 7a...Cleaning blade 7b...Magnetic roller 7c...Magnetic sensor 7d...Standing control plate 7f...Spherical magnetic particles Figure 1 of the stored hopper

Claims (1)

[Scope of Claims] 1. In an image forming apparatus using an amorphous silicon photoreceptor and equipped with a developing device using magnetic toner, a developing device using non-magnetic toner, and a magnetic roller as a cleaning means, the image forming apparatus is provided in a cleaner. What is claimed is: 1. An electrophotographic apparatus comprising: a magnetic sensor for detecting magnetic permeability; and means for maintaining the magnetic permeability of collected toner at a constant spike formation level. 2. The electrophotographic apparatus according to claim 1, wherein the means for maintaining magnetic permeability is configured to send and adhere magnetic toner to a magnet roller via a photoreceptor during a period when no transfer material is supplied. 3 As a means of maintaining magnetic permeability, the particle size is 30~
2. The electrophotographic apparatus according to claim 1, wherein the spherical magnetic particles of 200 μm are fed and deposited on a magnetic roller.