JPH0634136B2 - Image forming 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 more particularly to a cleaning apparatus therefor.

A well-known image forming apparatus that repeats the steps of forming a transferable image with toner on the surface of a running image carrier, transferring this to a transfer material, and then removing residual toner on the surface of the image carrier It is essential to maintain and improve the function of the cleaning device for removing the residual toner in order to obtain a high quality image. Various types of means for removing the residual toner have been proposed in the past, but the one using a cleaning blade made of an elastic material such as rubber is widely used in recent years because of its compact structure and excellent toner removing action. It has come to be used.

However, in the case of using such a cleaning blade, if the blade is constantly kept in pressure contact with the surface of the image carrier, the toner adhering to the vicinity of the blade adheres to the image carrier when the apparatus is not operating. In some cases, the blade may act to rub this toner against the image carrier during the next operation, resulting in fusing. Further, in the case where the surface of the image bearing member has a low hardness, if the blade is left in pressure contact with the surface of the image carrier, the pressure contact portion may be deformed, which may adversely affect the image formation.

In order to avoid such drawbacks, it has already been proposed that the cleaning blade is pressed against the surface of the image carrier only when the image forming apparatus is in operation and is separated from the surface of the image carrier when not in operation.

However, with such a configuration, the cleaning blade is usually configured to elastically press the surface of the image carrier at a predetermined pressure by using a spring or a weight. , When it is not activated, it is separated against the action of the spring and so on, so when the blade is brought into pressure contact with the surface of the image carrier at the moment of activation, it makes a shocking contact, and the blade itself is elastic. Since it is made of a material, it is largely bent at the time of contact, and not only the edge portion but also the flat portion thereof is in contact with the surface of the image bearing member. For example, as shown in the graph of FIG. Due to the elasticity of the blade itself and the elasticity of the supporting member of the blade, there is a tendency to gradually converge to a steady pressure contact force while varying the pressure contact force of the blade to the image carrier surface. Inevitable.

In such a case, the maximum pressure contact force at the time of pressure fluctuation becomes much larger than the steady-state voltage. Therefore, as described above, the cleaning blade largely bends at this point and the image carrier surface. There is a possibility of causing inconvenience such as fusion of toner and deformation and damage of the surface of the image bearing member due to the surface contact.

The present invention has been completed in order to cope with such a situation, and in a cleaning device using a cleaning blade, the cleaning blade which is deviated from the surface of the image carrier is described above in connection with the operation of the image forming apparatus. When pressure is applied to the surface, it takes a certain amount of time to reach a predetermined pressure while gently contacting the surface, and thus the cleaning blade itself is brought into a fixed position without excessive bending. Deformation of the carrier,
An object of the present invention is to provide a cleaning device capable of suppressing damage and fusion of toner, maintaining a stable cleaning action for a long period of time, and contributing to production of a high quality image.

In order to achieve the above object, the present invention provides an image carrier, a drive motor that rotates the image carrier, a cam that receives a driving force from the rotating image carrier, and a cam that rotates. A cleaning blade that can move between a contact position that contacts the image carrier and a separated position that is separated from the image carrier according to the amount of displacement of the contour, and the drive transmission state from the image carrier to the cam And a switching means for switching to a cutoff state, when the drive motor is energized and the image carrier starts to rotate, the cam rotates to move the blade from the separated position to the contact position, When the blade reaches a predetermined contact position, the switching means is cut off to fix the blade at the predetermined contact position, and when the drive motor is de-energized, the switching means is in the transmission state. And the image bearing after de-energization Causing the cam is rotated by the rotation margin is moved to the separation position from the contact position of the blade which is an image forming apparatus according to claim.

With this configuration, the cleaning blade is not excessively bent, and when the blade is brought into contact with or separated from the image carrier, the toner or the like is fixed to the image carrier or fused. It is possible to perform good cleaning for a long period of time without any occurrence.

(2) Configuration of the Invention Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an embodiment in which the present invention is applied to a copying machine using a rotating cylindrical image carrier.

A photoreceptor 1 which is formed in a cylindrical shape and rotates in the direction of arrow A in the figure.
A cleaning device 20 is disposed in close proximity to and substantially parallel to this.

A charger, an exposure part, a developing device, a transfer electrode and the like (none of which are shown) are arranged around the photoconductor 1, but these are not directly related to the present invention, and therefore description thereof is omitted. To do.

In the cleaning device 20, one edge of the cleaning blade 2 formed of an appropriate elastic material such as urethane rubber is supported by the support member 4, and the other edge is brought into contact with and separated from the surface of the photoconductor. It is arranged. Support member 4
Is swingably supported by a pin 3 provided at an appropriate position in the housing of the cleaning device.
The spring 5 extends in the direction away from, and one end of the spring 5 is locked to this portion, and the other end of the spring 5 is locked at a proper position in the housing of the cleaning device. 4, cleaning blade 2
Is given a tendency to rotate counterclockwise as a whole,
Therefore, it is assumed that the free edge of the cleaning blade is conditioned to contact the surface of the photoconductor.

A portion of the support member 4 extending to the left in the figure is in contact with a bell crank-shaped lever 6 rotatably attached to a shaft 6b fixed to a housing, and the lever 6 is a spring 7 Therefore, it is given a tendency to rotate counterclockwise in the drawing.

The other leg of the lever 6 is in contact with the cam 9 attached to the inside of the housing of the apparatus, and as will be described later, the rotation of the cam 9 causes the lever 6 to swing. Support member 4,
The cleaning blade 2 comes into contact with and separates from the photoconductor 1.

The cam 9 has a ball-shaped shape as shown in the figure, and has a first portion 9b having a gradually increasing radius and a second portion 9c having a rapidly changing radius.

The position shown by the solid line in FIG. 1 shows the position in the non-actuated state, and as can be seen immediately from the drawing, one leg of the lever 6 is located at the minimum radius of the first portion 9b of the cam. The lever 6 is located in a counterclockwise biased position, and the other leg is in contact with the support member 4 and is held in a clockwise rotation position.

Therefore, the cleaning blade 2 is located away from the surface of the photoconductor.

FIG. 2 is a schematic diagram showing the relationship between the photoconductor 1 and a cleaning device represented by a cam. The gear 1a that rotates with the drive of the photoconductor 1 includes intermediate gears 12, 13, ...
Via the clutch 10, which is a switching means for switching the drive transmission from the image carrier to the cam between the transmission state and the cutoff state, the gear 11 is connected to the cam 9 via the clutch 10. The clutch 10, which may be a spring clutch, an electromagnetic clutch, or the like, is turned on by turning on a drive motor (not shown) for the photoconductor.

Returning to FIG. 1, the solid line in FIG. 1 shows the case where the image forming apparatus is inoperative, and the cleaning blade 2 is at a position separated from the surface of the photoconductor as described above.

When the photoconductor is rotated from this state, the clutch is turned on accordingly, and the gear 1a and the intermediate gears 11, 1 are rotated.
The cam 9 rotates in the clockwise direction in the figure via 2, 13, ....
When the cam 9 rotates, the lever 6 rotates clockwise from the position indicated by the solid line in the figure, so that the support member 4 that abuts one leg of the lever rotates counterclockwise, and the cleaning is performed accordingly. The free end of the blade 2 gradually comes into pressure contact with the photoreceptor. The broken lines in the figure indicate the operating positions of the lever 6, the support member 4, the cleaning blade 2 and the like. When the cleaning blade 2 reaches the operating position, the cam stops the clutching operation so that it stops with the leg portion of the lever resting on the maximum radius portion, and the copying operation becomes possible.

When the copying operation is completed, or when the detector 14 arranged near the photoconductor detects the presence of the transfer material caught without separating from the photoconductor at the preceding transfer position (not shown), the photoconductor is driven. The power supply to the motor is released, the photoconductor drive motor is turned off, and the cam 9 and gear 1 are temporarily turned off.
It is directly connected to 1. At this time, the rotation of the photosensitive member causes the cam 9 to rotate a small amount, and the lever 6 rapidly rotates counterclockwise due to the presence of the second portion 9c of the cam and the action of the spring 7. The cleaning blade 2 is instantly released from the surface of the photoconductor. This makes it possible to prevent the transfer material from sticking to the position of the cleaning blade.

(3) Effects The present invention has the configuration described in detail above, and when the image forming apparatus is operated, the cleaning blade is slowly moved to the image carrier as shown by reference numeral (9b) in FIG. Since the blade is pressed against the surface of the image carrier and does not come into contact with the surface of the image carrier, the blade applies excessive pressure to the surface of the image carrier to damage it or fuse the toner on the surface. Therefore, a good cleaning action can be maintained for a long period of time and a stable image can be obtained.

Further, especially when the photoconductor stops in the case of an abnormality such as a jam, the cleaning blade is rapidly separated from the image carrier as indicated by reference numeral (9c) in FIG. As a result, the edges of the image carrier and the cleaning blade are not damaged.

Moreover, since the replacement operation of the cleaning blade is performed by utilizing the rotational residual power when the image carrier is stopped,
For this reason, a special mechanism and driving force are not required, and the structure is simplified accordingly, which contributes to cost reduction.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a cleaning device according to the present invention, FIG. 2 is a perspective view of an essential part showing a relational operation between the cleaning device and a photoconductor, and FIG. 3 is a blade pressure of a known cleaning device. FIG. 4 is a graph showing a temporal change in blade pressure of the cleaning device according to the present invention. 1 ... Photoconductor, 2 ... Cleaning blade, 4 ... Supporting member, 6 ... Lever, 9 ... Cam, 10 ... Clutch.

Claims (1)

[Claims] 1. An image carrier, a drive motor for rotating the image carrier, a cam that rotates by receiving a driving force from the rotating image carrier, and an image carrier according to a displacement amount of a contour of the rotating cam. A cleaning blade movable between a contact position in contact with the image carrier and a separated position separated from the image carrier, and a switching unit for switching drive transmission from the image carrier to the cam between a transmission state and a cutoff state. When the drive motor is energized and the image bearing member starts to rotate, the cam rotates to move the blade from the separated position to the contact position, and when the blade reaches a predetermined contact position, the switching is performed. The means is cut off to fix the blade in a predetermined contact position,
When the drive motor is de-energized, the switching means is in a transmission state, and the cam rotates due to the image bearing member rotation residual force after de-energization to move the blade from the contact position to the separated position. An image forming apparatus characterized by.