JPH0660862U - Cleaning device - Google Patents

Abstract

(57) [Summary] [Purpose] In an electrophotographic cleaning device,
Changes in drum surface resistance, blade tilt, blade wear, etc. are detected by the rotation torque of the drum 1, and the bite amount (pressure contact state) of the blade 8 is controlled to prolong blade life and maintain cleaning performance. Is intended. [Structure] In FIG. 1, a cleaner unit 7 is rotatably supported and its blade 8 is pressed against the surface of the drum 1 to remove residual toner. The rotation torque of the drum 1 is detected by using the drive current of the motor that rotates the drum 1, the eccentric cam 20 is rotated based on the detection output, and the free end of the cleaner unit 7 is changed up and down. The pressure contact state of the blade 8 is optimally controlled. According to the cleaning device of the present invention, stable cleaning performance can be obtained. In addition, the life of the blade can be extended.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a facsimile, and a printer.

[0002]

[Prior art]

 FIG. 1 is a cross-sectional side view of a main part of a cleaning device of a copying machine, in which the reference numerals 1 to 14 are prior art and the reference numerals 15 and above are provided by the present invention. In FIG. 1, reference numeral 1 is a selenium photosensitive drum, which is rotated in the direction of the arrow by a driving motor (not shown) during a copying operation. Reference numeral 2 denotes a toner collecting device, which is provided with a rotatable fur brush 4 at a collecting port of the receiving main body 3 and a toner carrying screw 5 at a bottom portion thereof. The fur brush 5 removes the toner on the drum surface while rotating with the rotation of the drum 1 or rotating by a motor dedicated to the fur brush, and the residual toner of the brush is removed by the contact piece 6. . The toner transport screw 5 transports the dropped toner to a predetermined place.

Reference numeral 7 is a cleaner unit for removing toner that could not be removed by the fur brush 4, which is scraped off by a blade 8 which is pressed against the surface of the drum 1. The cleaner unit 7 is rotatably supported by an angle (9) on the body side of the copying machine, and is pressed against the surface of the drum 1 by its own weight. Reference numeral 10 is a base plate angle, to which the blade 8 is fixed below the shaft support (9), and between the pair of bent pieces 11 on the free end side, a scraper 12 having a V-shaped cross section is provided between both side pieces 13. It is provided rotatably with respect to the substrate angle 10.

The scraper 12 removes toner stuck to the blade 8. For example, when the free end of the substrate angle 10 is manually lifted, the scraper 12 has a V-shaped top abutting against the main body of the copying machine (not shown). The toner is removed by hitting a part and moving the tip 14 relatively to the blade 8 side.

Cleaning is performed in order to obtain a clear image, and it is required to improve its cleaning performance. Therefore, in the above-mentioned conventional cleaning device, in order to stabilize the pressure contact force (linear pressure) between the drum 1 and the blade 8, the hardness, elasticity, modulus, etc. of the blade material are controlled and the amount of bite into the drum 1 side is controlled. The surface of selenium photoconductors with high surface resistance is polished and roughened. That is, in order to improve the cleaning performance, it is effective to increase the blade linear pressure, but on the other hand, there is a problem that the blade 8 wears faster and shortens the service life. The cleaning performance and blade life were maintained by balancing the surface conditions of the blades.

The surface of the selenium photoconductor is originally smooth, and the rougher the surface resistance, the lower the life of the blade 8. The relationship between the usage amount of the drum (the number of copies: K is 1000 sheets) and the life of the blade 8 is as follows as a result of the experiment, and the life of the blade 8 becomes shorter as the surface of the drum 1 wears and approaches the mirror surface. I see.

Drum usage amount Blade life 0 When used from 0 to 150K 150K When used between 100K and 200K 90K When used between 200K and 300K 70K When used between 300K and 400K 50K 400K When used between 5K and 500K 30K

[0008]

[Problems to be solved by the device]

 In the conventional cleaning device, the surface of the drum 1 gradually becomes a mirror surface due to the contact with the blade 8 and the developer, and the surface resistance increases accordingly. The more you use it, the shorter it becomes. In addition, reversion occurs.

When the edge of the blade 8 is worn out, the linear pressure is reduced and the toner removal performance is deteriorated, so that the wear limit wear amount of the blade is accelerated.

The blade collapse caused by pressing the blade 8 against the drum 1 causes biting and changes in linear pressure.

In order to solve such a problem, the present invention detects fluctuations in drum surface resistance value, blade tilt, blade wear, etc., with the rotation torque of the drum 1, and detects the bite amount of the blade 8 (pressure contact state). Is controlled to prolong the life of the blade and maintain the cleaning performance.

[0012]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides an image forming apparatus using an electrophotographic method in which a blade 8 of a cleaner unit 7 is pressed against the surface of a drum 1 to remove residual toner as shown in FIG. It is characterized in that a control means for controlling the pressure contact state of the blade 8 in accordance with the rotation torque of the drum 1 is provided.

Further, the control means is characterized by having a detection means for detecting the rotation torque of the drum by using a drive current of a motor for rotating the drum.

Further, the cleaner unit is rotatably provided, and the control means is rotated on the basis of the detection output of the detection means to eccentrically displace the position of the cleaner unit relative to the drum. It is characterized by having a cam.

[0015]

[Action]

 In the above configuration, the rotational torque of the drum 1 is detected by the motor drive current, and the stepping motor 18 is rotated in accordance with the detected current to control the position of the cleaner unit 7 to control the pressure contact force of the blade 8. Adjust to the optimum.

[0016]

【Example】

 FIG. 1 is a sectional side view of a main part of the cleaning device of the present invention, and the description of the same parts as those of the conventional device will be omitted.

In FIG. 1, reference numeral 15 is a weight provided on the free end side of the substrate angle 10 of the cleaner unit, and gives a force for rotating the cleaner unit in the arrow direction.

Reference numeral 16 denotes a pressure contact force control means, which includes a fixed angle 17 fixed to the main body of the copying machine, a stepping motor 18 provided on the fixed angle 17, detection means for detecting a drive current of the motor, and this detection means. A control circuit (not shown) for controlling the rotation angle of the stepping motor 18 by the output of the above is provided.

An eccentric cam 20 is fixed to a rotary shaft 19 of the stepping motor 18, and an outer peripheral surface of the eccentric cam 20 receives the free end of the cleaner unit 7. Therefore, the cleaner unit slightly moves up and down as the cam 20 rotates.

FIG. 2 shows the relationship between the blade biting amount and the motor current. The horizontal axis shows the biting amount (mm) and the vertical axis shows the current value (ampere). Further, A is a characteristic curve when a new drum (that is, a drum having a rough surface) 1 and a new blade 8 are used and the optimum biting amount of the blade 8 is set to 1.4 mm. Is a characteristic curve when the drum 1 whose surface is mirror-finished is used and C is a characteristic curve when a worn blade (about 20 micron wear) is used.

According to FIG. 2, even if the optimum bite amount is 1.4 mm, the driving current of the motor is 1.4 amperes (data A) depending on the states of the blade 8 and the drum 1. It varies from 7 amps (data B) to 1.2 amps (data C).

This shows that when the drum 1 is mirror-finished, the surface resistance value becomes high, the blade 8 is pulled by the drum 1, the tack-in amount increases, and the biting amount becomes large, which is the same state. ing. Moreover, it is shown that when the blade 8 is worn, the opposite state occurs.

Therefore, the tuck-in amount of the blade 8 is kept constant by changing the biting amount of the blade 8 so that the current value in the initial optimum setting state is 1.4 amperes, and the blade and blade It is possible to secure stable cleaning performance regardless of the state change.

For this reason, in the above configuration, the rotation torque of the drum 8 is detected by the drive current of the drum rotation motor by the detection means, for example, the current transformer, and stepping is performed by the control circuit (not shown) based on the detection output. The motor 18 is driven to rotate the eccentric cam 20. By this rotation, the free end of the substrate angle 10 mounted on the outer peripheral surface of the eccentric cam 20 is vertically changed, and the contact state between the blade 8 and the drum 1 is changed, so that the driving current is kept constant. .

The control circuit has a comparison comparator that compares the reference current (1.4 amperes) with the detection current from the detection means. Based on the output of this comparator, the rotation direction and the rotation amount of the stepping motor 18 are determined. Control. In this way, the linear pressure drop due to the wear of the blade 8 can be corrected, and the wear limit wear amount of the blade 8 is increased and the life can be extended. Also, the cleaning performance can be maintained.

[0026]

[Effect of device]

 According to the cleaning device of the present invention, stable cleaning performance can be obtained. In addition, the life of the blade can be extended. Furthermore, it is not necessary to set the bite amount when replacing the blade.

[Brief description of drawings]

FIG. 1 is a cross-sectional side view of essential parts of a cleaning device according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram for explaining the operation of the present invention.

[Explanation of symbols]

 1 Drum 7 Cleaner Unit 8 Blade 16 Control Unit 18 Stepping Motor 20 Eccentric Cam

Claims (3)

[Scope of utility model registration request] 1. An image forming apparatus using an electrophotographic system, wherein a blade of a cleaner unit is pressed against the surface of a drum to remove residual toner. A cleaning device provided with control means for corresponding control. 2. The cleaning device according to claim 1, wherein the control means has a detection means for detecting a rotation torque of the drum by using a drive current of the drum rotation motor. 3. The eccentric cam, wherein the cleaner unit is rotatably provided, and the control means is rotated based on a detection output of the detection means to displace the position of the cleaner unit relative to the drum. The cleaning device according to claim 1 or 2, further comprising: