JPH0642116B2 - Cleaning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Object of the Invention The present invention relates to an image forming apparatus utilizing an electrophotographic process such as an electrophotographic copying machine and a printer, and more particularly to a cleaning apparatus thereof.

The step of forming a transferable toner image on the running image carrier, transferring the toner image to a transfer material mainly composed of paper, and removing residual toner on the surface of the image carrier that did not contribute to the transfer is repeated. As a residual toner removing means in a known image forming apparatus to be returned, a cleaning blade made of an elastic material such as urethane rubber has been widely used because of its excellent toner removing function.

However, the substances that adhere to the surface of the image carrier are not only toner, but also minute paper pieces generated from the transfer paper, dust in the air, rosin and talc deposited from the transfer paper, or high pressure inside the image forming apparatus. There are various foreign substances such as corona products due to the presence of the member, and the cleaning blade exerts an excellent function for removing toner, but it is not always effective for the various foreign substances as described above.

When such a foreign substance adheres to the surface of the image bearing member, it absorbs moisture in the air to lower the resistance, which may cause image deletion.

In order to avoid such inconvenience, it has been proposed to supply an abrasive to the surface of the image bearing member in order to remove the foreign substance from the surface, but the action is not stable and satisfactory. The desired result is not obtained.

Further, the applicant has provided a magnet roller and the like in close proximity to the image carrier to capture and convey the small toner removed from the surface of the image carrier. Then, a method is proposed in which the surface of the image bearing member is rubbed with this toner to remove foreign matter. Although such a substance has an excellent function of removing foreign matter, it accumulates a large amount of toner, which scatters out of the cleaning device to contaminate each part or cause an inconvenience such as adversely affecting image formation, Since the toner rubs against the image bearing member, the burden of cleaning becomes large, which may cause cleaning failure.

The present invention has been made to cope with such a situation, by detecting the humidity near the surface of the image carrier,
Only when this reaches a preset humidity, a large amount of toner is supplied to the surface of the image carrier, and the surface is rubbed to remove the above-mentioned foreign matter, and cleaning is performed so that a good image can always be stably obtained. The purpose is to obtain a device.

(2) Structure of the invention In order to achieve the above object, the present invention provides a cleaning blade for cleaning the surface of the image carrier after transferring the toner image to the recording material, and a cleaning blade provided on the upstream side in the rotational direction of the image carrier. And a rotatable magnet roller carrying on its surface the magnetic toner removed from the image carrier by the blade, and a magnetic toner carried on the roller surface and moving with the rotation of the roller between the image carrier and the roller. In a cleaning device having a damming member for damming between and rubbing the image carrier surface with the magnetic toner dammed by the damming member, when the humidity in the vicinity of the image carrier is lower than a predetermined value, It is characterized in that it is provided with means for reducing the amount of toner blocked by the blocking member compared to when the humidity is higher than a predetermined value.

With such a configuration, an appropriate amount of magnetic toner can be stored at a predetermined position depending on the environmental humidity, so that good cleaning can always be stably performed.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a side view of essential parts showing a case where the cleaning device according to the present invention is applied to a copying machine using a rotating cylindrical photoconductor. A cleaning device 2 extending parallel to the axial direction of the photoconductor is arranged at a predetermined position near the photoconductor 1, and magnetic toner is used as the toner.

Around the periphery of the photoconductor, means for uniformly charging the photoconductive layer on the surface of the photoconductor, means for irradiating a photoimage on the photoconductive layer to form an electrostatic latent image, developing means for visualizing the latent image, Means for transferring the toner image to the transfer material are provided, but since they are not directly related to the present invention, description thereof will be omitted.

The cleaning device 2 includes a cleaning blade 3
Is disposed, and the edge of the edge is pressed against the surface of the photoconductor to scrape off the toner that does not contribute to the transfer in the transfer means and remains attached to the photoconductor when it reaches the blade. It is assumed that the scraped off toner is captured by the magnet roller 4, further reaches the small toner storage portion in the cleaning device with the rotation thereof, and is discharged to the outside of the cleaning device by the screw conveyor 5 as necessary. .

In such a cleaning device, in the present invention, a scraper member 6 that comes into contact with and separates from the magnet roller 4 is arranged in the device.

As shown in FIG. 2, the scraper member 6 is composed of a plate member 6b having a proper number of openings 6c and a support rod 6a attached to the plate member 6b, and is mounted in the cleaning device.
It is rotatable at that position and can selectively take a position shown in a solid line in FIG. 1 where it abuts against the magnet roller and a dotted line position separated therefrom.

FIG. 3 schematically shows the means for swinging the scraper member 6 as described above. The spring 7 is attached to one of the wires 8 wound around the pulley 9 attached to the end portion of the support rod 6a. Then, the plate body 6b is always given a turning tendency in the counterclockwise direction in the drawing, and the other end of the wire is attached to the solenoid SOL. Therefore, by urging the solenoid, the wire 8 is pulled against the action of the spring 7, and the pulley 9 is pulled.
Therefore, the scraper member 6 can be rotated clockwise in the drawing.

FIG. 3b shows a configuration in which the scraper can be displaced in a stepwise manner. With such a configuration, the toner amount can be further suitably adjusted.

In this case, the scraper 6 is supported by a swing fulcrum 6a, and a cam 10 is attached to a roller 12 attached to one end thereof.
Are in contact. The cam 10 is rotatable about an axis 11a, a one-way clutch 11 is coaxially arranged, and the one-way clutch is operated by a lever L.

A solenoid SOL is attached to the free end of the lever,
One-way clutch by the energizing of this solenoid,
Therefore, the cam 10 can be rotated stepwise, so that the solenoid can be energized several times to set the positions of the scraper in accordance with the position of the cam surface.

A ceramic humidity sensor made of, for example, a porous sintered body made of MgCr ₂ O ₄ and TiO ₂ is used in the vicinity of the periphery of the photoconductor 1, and the humidity sensor is arranged at a proper position near the photoconductor surface (not shown).
Input the output to the CPU. The CPU arithmetically processes the output of the humidity sensor, and when the set humidity is, for example, RH of 70% or more, the solenoid of the scraper member 6 is turned on to bring the scraper member closer to the magnet roller 4 and convey toner on the surface thereof. Then, the surface of the photoconductor is rubbed with the collected toner to remove the above-mentioned foreign matter adhering thereto. When the humidity falls below 70%, the solenoid is turned off, the scraper member 6 is separated from the roller 4, and the toner is conveyed to the storage section in the cleaning device.
Do not rub the photoreceptor with toner.

FIG. 4 is a flow chart showing the above operation.

In the above case, the solenoid is in the ON state from the pre-rotation of the photoconductor to the post-rotation of the post-copy.However, the ON time of the solenoid can be changed variously by using the timer according to the output value of the humidity sensor. You can FIG. 5 is a graph showing a case where the on-time of the solenoid is changed stepwise by dividing the humidity value into predetermined ranges, and FIG. 6 is a graph showing a case where the on-time is controlled continuously.

FIG. 7 shows a case where the amount of toner stored is changed by changing the position of the scraper member depending on the humidity. For example, in the cleaning device as shown in FIGS. 1A and 1B, the gap l between the magnet roller 4 and the inner surface of the cleaning device casing in the vicinity thereof.
₂ is 2 mm, the distance l ₁ between the magnet roller and the photoconductor is 3 mm
Then, when the scraper member 6 is separated from the toner, the toner conveyed by the magnet roller is
The height of the magnetic brush is approximately 2.5 mm at the interval l _1.
It does not come into contact with the photoconductor. The scraper member 6 is moved closer to the magnet roller, and the distance corresponding to the symbol L in FIG. 1 is changed to change the toner accumulation amount and change the rubbing action of the toner. The foreign matter can be removed more strongly.

When the above-mentioned humidity set value, for example, 70% or less, the toner is configured so as not to rub against the photoconductor as in the above example, so that the specific charge is high and the toner is adsorbed to the photoconductor at low humidity. It is preferable to supply a larger amount of easy toner to the position of the cleaning means such as the cleaning blade to increase the cleaning load and prevent the occurrence of defective cleaning.

(3) Effect of the Invention The present invention has the configuration and operation described above, and the toner is rubbed against the surface of the image carrier only when the periphery of the image carrier is in a high-humidity atmosphere. In addition, it is possible to reliably prevent foreign matters such as deposits from transfer paper and corona products from lowering the resistance of the image bearing member surface and adversely affecting the image formation. At times, a large amount of toner is not supplied, so a small amount of toner as a whole provides a sufficient rubbing effect, which damages the image bearing member and scatters the toner to stain each part of the image forming apparatus. Alternatively, it is possible to avoid a situation where a cleaning failure is caused by applying an excessive load to a cleaning means such as a cleaning blade, and it is possible to stably obtain a high-quality image for a long period of time. It is a thing.

[Brief description of drawings]

FIG. 1 is a side view of an essential part showing an embodiment of a cleaning device according to the present invention, FIG. 2 is a partial plan view showing the configuration of a scraper member, and FIG. 3a is an explanatory view showing an example of a mechanism for operating the scraper member. 3b is an explanatory view showing another example of the mechanism for operating the scraper member, FIG. 4 is a flow chart showing an operation mode of the cleaning device according to the present invention, and FIGS. 5, 6, and 7 show humidity and humidity. It is a graph which shows the relationship with the operation of a scraper. 1 ... Photoconductor, 2 ... Cleaning device, 3 ... Cleaning blade, 4 ... Magnet roller, 6 ... Scraper member.

Claims (1)

[Claims] 1. A cleaning blade for cleaning the surface of an image carrier after transferring a toner image on a recording material, and a magnetic member provided on the upstream side in the rotational direction of the image carrier and removed from the image carrier by the blade. A rotatable magnet roller that carries toner on its surface; and a damming member that dams magnetic toner carried on the surface of the roller and moving with the rotation of the roller between the image carrier and the roller, In a cleaning device that rubs the surface of an image bearing member with magnetic toner blocked by a blocking member, when the humidity in the vicinity of the image bearing member is lower than a predetermined value, the amount of toner blocked by the blocking member is A cleaning device comprising means for reducing the amount of the cleaning liquid when it is higher than a predetermined value.