JPH0122023B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an apparatus, etc. that cleans and collects toner remaining on the surface of a photoreceptor without being transferred to recording paper in an apparatus using an electrophotographic process, and reuses the toner. This is related to the improvement of.

BACKGROUND OF THE INVENTION In a typical copying method using an electrophotographic process, first, in a dark place, the surface of a photoreceptor, which has a photoconductive insulating film attached to a conductive support, is uniformly charged by corona discharge.

Next, the original image to be copied is exposed to light to form an electrostatic latent image. This electrostatic latent image is developed by magnetic brush development. The obtained toner image is transferred to paper, but since the toner image is usually not completely transferred, it is necessary to clean the surface of the photoreceptor. The final step is to melt and fix the toner onto the transfer paper.

Although the copying method using the electrophotographic process has been briefly described above, the present invention relates to a technology related to a dust collector in the final stage of the post-transfer cleaning process.

In a typical electrophotographic copying machine, a rotating drum is used as the photoreceptor, and in order to perform repeated copying, it is necessary to clean toner remaining on the photoreceptor drum due to insufficient transfer. There is a method using a brush as this cleaning means. In this brush cleaning device, a rotating brush is brought into contact with the surface of a rotating photoreceptor drum, and the toner remaining on the photoreceptor drum is scraped off with the bristles of the brush and drawn out by an air flow. The drawn toner is collected in the cyclone separator dust collector, but the collected toner cannot be automatically and continuously carried out while the cyclone separator is in operation and supplied to the developer toner box as recycled toner. I couldn't do it. The reason for this is that the inside of the cyclone separator dust collection section has a negative pressure of about 100 to 300 mmAq, and if an ejection path is provided to automatically and continuously collect the collected toner from the dust collection section, the dust will be collected through the same section. This is because air flows into the chamber, significantly reducing the separation efficiency of the cyclone separator.

In order to solve this problem, a method of taking out the collected toner using a rotary valve has already been proposed (see, for example, Japanese Patent Laid-Open No. 56-93624).
Specifically, as shown in FIG. 1, a rotary valve 7 having a plurality of blades is disposed at the bottom of the cyclone separator 1, and the collected toner in the cyclone separator 1 is removed by rotation of the valve 7. Take out sequentially,
The toner is continuously supplied to the toner box 21 of the developing device 20 by an auger 8 which is a screw type conveyor.

Problems to be Solved by the Invention However, the cyclone separator used for toner recovery in the above-mentioned electrophotographic copying machine is generally made of plastic due to its advantages of being inexpensive and lightweight.

However, due to the general physical properties of plastic as a material, it has a high electrical resistance, so if static electricity is generated due to frictional charging due to contact with the swirling airflow of toner mixture inside the cyclone, the static electricity will be conducted to the outside and will not be eliminated and will accumulate and become charged. become.

When the amount of accumulated charge reaches a sufficient amount to be discharged to a conductive member adjacent to the outside of the body, electrical insulation breakdown occurs as an instantaneous spark discharge phenomenon, causing static electricity to be discharged from the plastic body to the conductive member. This will cause an adverse effect, such as acting as noise on electrical circuits.

Means for Solving the Problems The present invention provides a means for preventing the electrostatic charge that causes the above-mentioned spark discharge phenomenon, by making the plastic of the cyclone component electrically conductive, such as the electrically conductive member frame of an electrophotographic copying machine, etc. This eliminates the drawbacks associated with conventional plastic materials by grounding the material through the material.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 2, a charger, an exposure system, a developing device 20, a transfer device, and a cleaning device 30 are arranged around the photosensitive drum 10 in a normal layout. The toner image formed on the photoreceptor drum 10 is transferred to paper in a transfer process, but residual toner adheres to the surface of the photoreceptor after the transfer. This residual toner is removed by a cleaning device 30.

An AC voltage (AC-) on which a negative bias voltage is superimposed is applied to the entrance side of the cleaning device 30.
A static eliminating corotron 31 and a static eliminating lamp 32 to which a voltage of 6 KV, DC-2 KV) is applied are provided. In the cleaning device 30, first and second brush rolls 3 each include an insulating woven fiber brush.
3 and 34 are approximately 1.5 mm relative to the photoreceptor drum 10.
They are arranged so that they touch each other with a nip at a depth of about 100 mL. Moreover, both rolls 33 and 34
are rotated at 1200 rpm in the opposite direction and the same direction as the rotation of the photoreceptor drum 10, respectively. Furthermore, first and second flick bars 35, 36 are in sliding contact with both rolls 33, 34;
The first and second fritz coverrs are DC high voltage power supplies 37 (DC+4KV) and 38 (DC-4KV), respectively.
It is connected to the.

Therefore, the residual toner after the transfer is strongly electrostatically attached to the surface of the photoreceptor drum 10, and as the photoreceptor drum 10 rotates, the cleaning device 30
reach the position. Before entering the section, first, static electricity is removed from the surface of the photoreceptor drum 10 and residual toner by the AC discharge of the static elimination corotron 31 and the action of the static elimination lamp 32, and then by the (-) DC discharge of the static elimination corotron 31. Photosensitive drum 1
0 surface and residual toner are charged (-). Therefore, the residual toner adheres to the surface of the photosensitive drum 10 in an extremely unstable state, enters the cleaning device 30, and comes into contact with the first brush roll 33.

The first brush roll 33 is charged (+), and when it comes into contact with the residual toner that is unstablely attached to the surface of the photoreceptor drum 10, the residual toner is removed by electrostatic adsorption and mechanical removal. The portion of the photoreceptor drum 10 is electrically charged (-) and is removed from the surface of the photoreceptor drum 10 .

Further, approximately 10% of the remaining toner that has adhered to the surface of the photoreceptor drum 10 in an unstable state is charged to (+), and the second brush roll 34
I approach it as such.

Since the second brush roll 34 is (-) charged, the (+)-charged residual toner is electrostatically attracted and mechanically removed, so that the residual toner is completely removed from the surface of the photoreceptor drum 10. Removed and cleaned.

In addition, the first and second brush rolls 33, 34
The toner removed from the surface of the photoreceptor drum 10 by the action of is brushed off from the brush fibers of each brush roll 33 and 34 by the action of the first and second frit cover bars 35 and 36, and then transferred to the cleaner duct by the suction force of the blower. 39, is conveyed to the cyclone separator 1 together with the air stream through the connecting duct 40.

In FIG. 1, the main body 1 of the cyclone separator 1
The toner particles contained in the air entering through the inlet 2 extending in the tangential direction of the upper outer wall a become a swirling flow 5 along the inner wall of the main body 1a due to centrifugal force, and are separated from the air flow and descend to collect dust. The settled toner is collected from the port 4 and carried out to the lower space A by the action of the rotating rotary valve 7 without breaking the airtightness of the cyclone separator 1. The discharged toner is conveyed by the rotating auger 8 and collected as recycled toner into the toner box 21 of the developing device 20.

On the other hand, the air from which the powder has been separated is reversed and discharged from the central outlet 3.

The plastic material of the main body 1 has a volume resistivity of 10 ¹⁰ Ω・cm or less to make it conductive.
In addition to using a mixture of woven fibers such as carbon or aluminum or powder conductive material, another method is to use ordinary plastic material and plate or paint the surface with conductive material. It is clear that this can also be done as appropriate.

Effects of the Invention As described in detail above, the present invention provides that static electricity generated due to contact friction between the inner wall of the main body 1a and the swirling flow 5 is grounded along the main body 1a and transferred to the outside where it is eliminated. This means that it is possible to prevent the conventional problems caused by

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a cyclone separator according to the present invention, and FIG. 2 is an explanatory diagram of essential parts of an electrophotographic copying machine equipped with a toner recovery device according to an embodiment of the present invention. 1: cyclone separator, 2: inlet, 3: outlet,
4: dust collection port, 5: swirling flow, 6: grounding, 7: rotary valve, 8: auger, 10: photosensitive drum, 20: developer, 30: cleaning device, 3
1: Static elimination corotron.

Claims (1)

[Claims] 1. A cyclone separator made of plastic for separating and recovering powder and granules from a mixed fluid of powder and gas, characterized in that its main body is conductive and grounded.