JPH0725807Y2 - Development device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a developing device of an electrophotographic copying machine.

<Prior Art> Conventionally, in a developing device of a copying machine that uses a two-component developer composed of toner and carrier, a scraper made of a plate or a round bar is fixed to the developing roller at a constant distance. This scraper has the function of peeling the developer that has become under toner after development from the developing roller and sending it to the agitating part with the replenished toner to agitate the toner and the developer to constantly stabilize the toner concentration. It has a function of circulating the developer in the tank to effectively use the entire amount of the developer.

<Problems to be Solved by the Invention> However, in the above-mentioned conventional technique, the developer attached to the developing roller is scraped off by a scraper fixed in proximity to the developing roller regardless of whether or not it is used for development. Be done. At this time, stress such as friction is applied to the developer by the scraper, peeling of the coating material of the carrier, pulverization, or adhesion of toner to the surface of the carrier (known as spent toner), which shortens the life of the developer. Then there are problems.

In view of the above, the present invention aims to provide a developing device capable of extending the life of the developer by reducing the stress applied to the developer.

<Means for Solving the Problems> In the means for solving the problems according to claim 1 of the present invention, as shown in FIGS. 1 to 4, a developing roller 13 is rotatably supported by a developing tank 12 and is in proximity to the developing roller 13. Then, a peeling member 15 for peeling off the developer D on the developing roller 13 is provided, and the peeling member 15 comes close to the developing roller 13 to peel off the developer D and agitate the developer D from the developing roller 13. It is possible to switch to a resting posture B for separating the developer D to reduce the stress on the developer D, and a driving unit 16 for switching the peeling member 15 between the working posture A and the resting posture B, and to replenish the developing tank 12 with toner. A toner replenishing means 14 and a control unit 17 for controlling the drive unit 16 so that the peeling member 15 is in the operating posture A when the toner is replenished and in the rest posture B when the toner is not replenished are provided.

According to the second aspect, as shown in FIG. 6, the control unit 17 for controlling the drive unit 16 is provided with the developing-time driving means 33 for setting the peeling member 15 in the operating position A during development and in the rest position B during non-developing. It is a thing.

In the third aspect, as shown in FIGS. 7 and 8, the control unit 17 for controlling the drive unit 16 causes the peeling member 15 to be in the working posture A when the toner replenishment time is a certain time or more, and the rest posture B when the toner replenishment time is less than the certain time.
The drive means 34 for continuous toner supply is provided.

<Operation> In the problem solving means according to claim 1, when the toner density becomes equal to or lower than the reference value, the toner replenishment signal is output from the control section 17 and the toner is replenished to the developing tank 12 from the toner replenishment means 14. At this time, at the same time, the driving unit 16 is operated and the peeling member 15 is switched to the working posture A.

The developer D is peeled from the developing roller 13 by the peeling member 15, flows as shown by an arrow X in FIG. 2, and is agitated with the replenished toner. Then, the developer D recovers the toner concentration to the original level, and is conveyed to the photoconductor 2 again with the rotation of the developing roller 13 and is used for development.

If the toner concentration is equal to or higher than the reference value, the peeling member 15 is held in the resting posture B, and the developer D passes between the developing roller 13 and the peeling member 15 as shown by an arrow Y shown in FIG. Used for development.

Therefore, when the toner is replenished, the peeling member 15 is interlocked with the working posture A so that the developer D having a reduced toner concentration after development is not used again for development, and the developer D is agitated. The developer tank 12
The circulation efficiency of the developer D in the inside increases, the developer D is uniformly and effectively utilized, and the image quality can be stabilized.

Further, when toner is not replenished, the peeling member 15 is placed in the resting posture B to reduce the frictional resistance of the developer D and reduce the stress applied to the developer D. Peeling, pulverization, or spent toner can be prevented, and the life of the developer D can be extended.

In the second aspect, when copying is started, the developing drive unit 33 is activated and the peeling member 15 is switched to the operating posture A.

The developer D is separated from the developing roller 13 and agitated with the replenished toner.

Then, when copying is completed and the developing roller 13 is stopped,
The peeling member 15 is switched to the resting posture B.

Therefore, the peeling member 15 takes the operating position A when the developer D at the time of development is consumed and sends the developer D to the agitating portion with the toner, so that the toner concentration is kept constant,
The image quality can be stabilized. Further, since the resting posture B is set during non-development, the developer D is not agitated unnecessarily, stress on the developer D is reduced, and the life can be extended.

In claim 3, when the toner density falls below the reference value and becomes under toner, a toner replenishment signal is output from the control unit 17, and the toner continuous replenishment time drive means 34 counts this toner replenishment signal to keep it constant. When it is continuously output for a time or more, the peeling member 15 is switched to the working posture A. Also,
When the toner replenishment signal is less than the fixed time, the peeling member 15 is held in the resting posture B.

Therefore, the stress applied to the developer D is reduced, which is effective in extending the life of the developer D.

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

[First Embodiment] FIG. 1 is a sectional view of a developing device showing the embodiment of the present invention.
The figure also shows the operating state of the peeling member, FIG. 3 also shows the resting state of the peeling member, FIG. 4 is a control block diagram, and FIG. 5 uses the developing device of the present invention. It is a schematic diagram of a copying machine.

The copying machine using the electrophotographic method according to the present embodiment is the fifth
As shown in the figure, the photoconductor 2 rotatably supported by the copying machine main body 1, the charging device 3 for charging the photoconductor 2, and the original document on the document table 4 are irradiated with light to form the original image on the photoconductor 2. An optical system 5 including a lamp, a mirror, etc., which is projected on the surface to form an electrostatic latent image.
A developing device 6 that visualizes the electrostatic latent image into a toner image, a transfer device 8 that transfers the toner image onto the transfer paper conveyed from the paper feeding device 7, and a charge on the photoreceptor 2 after transfer. It is composed of a static eliminator 9 for removing static electricity, a cleaning device 10 for removing the residual toner on the photoconductor 2, and a fixing device 11 for fixing the toner transferred onto the transfer paper.

In the developing device 6 of this embodiment, as shown in FIGS. 1 to 4, the developing roller 13 is rotatably supported by the document tank 12 and the developing agent on the developing roller 13 is close to the developing roller 13. A peeling member 15 for peeling off D is provided, and the peeling member 15 is in proximity to the developing roller 13 and has an operating posture A for peeling off the developer D and stirring with the toner. It is possible to switch to a resting posture B to reduce stress,
A drive unit 16 for switching the peeling member 15 between the operating posture A and the resting posture B, and a toner replenishing means for replenishing the developing tank 12 with toner.
14 and the driving member 16 so that the peeling member 15 is in the operating posture A when toner is replenished and in the rest posture B when toner is not replenished.
And a control unit 17 for controlling the.

As shown in FIG. 1, the developing tank 12 is disposed close to the photoconductor 2 and has the developing roller 13 and the stirring roller 18 rotatably incorporated therein. Toner replenishing tank 19 which is a part of toner replenishing means 14 for replenishing toner
Is detachably attached.

A toner concentration sensor 20 is disposed below the developing roller 13 so as to project from the bottom wall 12a of the developing tank 12 into the tank. The toner concentration sensor 20 detects the mixture ratio of the carrier and the toner in the developer as a change in magnetic permeability and converts the change into an electric signal to control the toner. Are driven and controlled.

The developing roller 13 has an opening 12b in the developing tank 12 on the side of the photoconductor 2.
And is disposed in the vicinity of the photoconductor 2 and includes a magnet body 22 fixed to the developing tank 12 and a sleeve 23 rotatably fitted around the outer circumference of the magnet body 22. The rotation direction of the sleeve 23 is opposite to the rotation direction of the photoconductor 2.

As the magnet body 22, a magnet having five poles is used in order to improve the transportability of the developer around the toner concentration sensor 20.

The agitating roller 18 is arranged on the side farther from the photoconductor 2 than the developing roller 13, and is rotated in the direction opposite to the sleeve 23 of the photoconductor 2.

A developing tank is provided above the stirring roller 18 on the side opposite to the photoconductor 2.
A replenishment port 24 that connects 12 and the toner replenishment tank 19 is formed,
A toner replenishing roller 21 forming a part of the toner replenishing means 14 is rotatably supported in the replenishing port 24.

The peeling member 15 is composed of a long plate having a tongue-shaped cross section, is arranged between the developing roller 13 and the stirring roller 18 in parallel to the axial direction of the developing roller 13, and is rotatably supported by the developing tank 12. Axis 25
It is fixed to.

The drive unit 16 is composed of a solenoid 26 for rotating the mounting shaft 25 of the disposing member 15, the solenoid 26 is fixed to the developing tank 12, and the actuator 26a of the solenoid 26 controls the end of the mounting shaft 25. It is attached to one end of a penetrating horizontal bar 27, a tension spring 28 for urging the peeling member 15 toward the photoconductor 2 is attached to the other end of the horizontal bar 27, and the other end of the tension spring 28 is attached to the developing tank 12. It is fixed.

When the solenoid 26 is turned on, the peeling member 15 is rotated to the right as shown in FIG. 3 to the resting posture B, and when the solenoid 26 is turned off, the tension spring 15 is turned on as shown in FIG.
It is rotated to the left by 28 to be in the operating posture A.

The control unit 17 comprises a one-chip micro computer, the toner concentration sensor 20 is connected to the input side,
There is provided toner control means 29 for driving the toner replenishing roller 21 of the toner replenishing means 14 when the toner concentration falls below the reference value and becomes under toner.

Then, by the output from the toner control means 29, the peeling member
Toner replenishment driving means 30 for controlling the driving portion 16 so as to switch 15 to the working posture A is provided. The toner replenishment drive means 30 does not operate when the amount of toner to be developed is small and does not reach the toner replenishment level, or during the pre-rotation during warm-up and the post-rotation after development, and the peeling member 15 is in the resting posture B. It has the function of holding it as it is.

In the above configuration, the copying operation will be described. When the copy switch is turned on, the photoconductor 2 rotates, and the charging device 3 uniformly charges the surface of the photoconductor 2. Then, the original image is exposed on the photoconductor 2 by the optical system 5 to form an electrostatic latent image, and the developer D comes into contact with the developing device 6 to form a toner image. The toner image is transferred to the transfer paper by the transfer device 8,
The transfer paper is conveyed to the fixing device 11 and the toner is fixed.
The charge on the surface of the photoconductor 2 after the transfer is removed by the charge removing device 9, and the developer D that has not been developed is removed from the photoconductor 2 by the cleaning device 10. In this way, a series of copying operations is completed.

At this time, in the developing device 6, the peeling member 15 is held in the resting posture B, so that the developer D whose toner concentration has decreased after development is accompanied by the rotation of the sleeve 23 and the developing roller.
It passes between 13 and the peeling member 15. Then, the toner density sensor 20 measures the toner density after development.

If the toner density is equal to or higher than the reference value, this state is maintained and the developer D flows as shown by an arrow Y in FIG. Further, the peeling member 15 is maintained in the resting posture B even when the amount of toner to be developed is small and does not reach the toner replenishment level, or during pre-rotation during warm-up and post-rotation after development.

When the toner concentration falls below the standard value, the toner concentration sensor
The toner control means 29 detects the under toner by the output from 20, and outputs a toner replenishment signal to drive the toner replenishing roller 21. Then, the toner replenishing roller 21 rotates to replenish the developing tank 12 with toner. At this time, at the same time, the toner replenishing drive means 30 is operated to turn off the solenoid 26, and the peeling member 15 is switched to the operating position A by the urging force of the tension spring 28.

The developer D is peeled from the developing roller 13 by the peeling member 15 and flows as indicated by an arrow X in FIG.
It is sent in the direction of 18 and is agitated with the replenished toner. Then, the developer D recovers the toner concentration to the original level, and is conveyed to the photoconductor 2 again as the sleeve 23 rotates, and is used for development.

Therefore, when the toner is replenished, the peeling member 15 is interlocked with the working posture A so that the developer D having a reduced toner concentration after development is not used again for development, and the developer D is agitated. The developer tank 12
The circulation efficiency of the developer D in the inside increases, the developer D is uniformly and effectively utilized, and the image quality can be stabilized.

Further, when toner is not replenished, the peeling member 15 is placed in the resting posture B to reduce the frictional resistance of the developer D and reduce the stress applied to the developer D. Peeling, pulverization, or spent toner can be prevented, and the life of the developer D can be extended.

[Second Embodiment] FIG. 6 is a control block diagram showing a second embodiment of the present invention. Then, as shown in the figure, the control unit 17 of the present embodiment starts from the copying start means 32 and the copying start means 32 that starts the copying operation by actuating the photoconductor 2, the developing roller 13, etc. by turning on the copying switch 31. Output means to control the drive unit 16 to switch the peeling member 15 to the working posture A.
And are provided.

The developing drive means 33 has a function of holding the peeling member 15 in the resting posture B during non-developing, which is not a copying operation. The other structure is the same as that of the first embodiment.

In the above configuration, when the copy switch 31 is turned on,
The copying start means 32 operates, the photoconductor 2 rotates, and the developing roller 13 also drives. The developer D is conveyed to the photoconductor 2 as the sleeve 23 rotates and used for development. And
The unused developer D is conveyed by the sleeve 23 as it is.

At this time, by the operation of the copy start means 32, the drive means at the time of development
33 is actuated, the solenoid 26 is turned off, and the peeling member 15 is switched to the working position A by the urging force of the tension spring 28.

As described in the first embodiment, the developer D is separated from the developing roller 13 and agitated with the replenished toner.

Then, when copying is completed and the developing roller 13 is stopped,
The solenoid 26 is turned on, and the peeling member 15 is switched to the resting posture B.

Therefore, the peeling member 15 takes the operating position A when the developer D at the time of development is consumed and sends the developer D to the agitating portion with the toner, so that the toner concentration is kept constant,
The image quality can be stabilized. Further, since the resting posture B is set during non-development, the developer D is not agitated unnecessarily, stress on the developer D is reduced, and the life can be extended.

[Third Embodiment] FIG. 7 is a control block diagram showing a third embodiment of the present invention, and FIG. 8 is a view showing the operation timing of the peeling member.

As shown in the figure, the control unit 17 of the present embodiment outputs a toner replenishment signal to the toner replenishing roller 21 of the toner replenishing means 14 when the output signal of the toner concentration sensor 20 falls below the reference value and becomes under toner. Toner control means 29 driven by
Then, when the toner replenishment signal from the toner control means 29 is counted and continuously output for a fixed time or more (six times or more in this embodiment), the drive unit 16 is controlled to switch the peeling member 15 to the working posture A. The driving means 34 for continuously replenishing toner is provided. Further, the continuous toner replenishment drive means 34 is
It has a function of holding the peeling member 15 in the resting posture B when the toner supply signal is less than 6 times.

The other configurations are the same as those of the first embodiment, and the same operational effects are obtained, but when the toner replenishment from the toner replenishing roller 21 becomes a certain time or more, the peeling member 15 becomes the operating posture A and the certain time is maintained. When it is less than the above, the resting posture B is maintained, so that the stress applied to the developer D is further reduced, which is effective in extending the life of the developer D.

It should be noted that the present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

<Effect of the Invention> As is apparent from the above description, according to claim 1 of the present invention, a peeling member for peeling the developer on the developing roller is provided in the vicinity of the developing roller, and the peeling member is provided on the developing roller. It is possible to switch between an operating posture in which the developer is peeled off in close proximity and agitated with the toner, and a resting posture in which the developer is separated from the developing roller to reduce stress on the developer, and by placing the peeling member in the working posture during toner supply, The developer whose toner concentration has decreased after development is not used for development again, and the developer is sent to the toner agitator, so the circulation efficiency of the developer in the developer tank is increased and the developer is used uniformly and effectively. Therefore, the image quality can be stabilized.

Also, when the toner is not replenished, by placing the peeling member in the resting position, the frictional resistance of the developer is reduced and the stress on the developer is reduced. Alternatively, spent toner can be prevented, and the life of the developer can be extended.

According to the second aspect of the present invention, since the peeling member is provided with an actuating position during development and a resting position during non-developing, the peeling member is actuated when the developer during development is consumed. It takes a posture and sends the developer to the stirring section with the toner. The toner density is kept constant and the image quality can be stabilized. Further, since the developer is in a resting posture during non-development, unnecessary agitation of the developer is not performed, stress on the developer is reduced, and the life can be extended.

According to the third aspect of the present invention, since the peeling member is provided with the driving means for continuously supplying toner when the toner replenishing time is a fixed time or more and is in the resting posture when the toner replenishing time is less than the fixed time, the stress applied to the developer is prevented. It will be further reduced, which is effective in extending the life of the developer.

[Brief description of drawings]

FIG. 1 is a sectional view of a developing device showing an embodiment of the present invention, and FIG.
The figure also shows the operating state of the peeling member, FIG. 3 also shows the resting state of the peeling member, FIG. 4 is a control block diagram, and FIG. 5 uses the developing device of the present invention. FIG. 6 is a control block diagram showing a second embodiment of the present invention, FIG. 7 is a control block diagram showing a third embodiment of the present invention, and FIG. 8 is the operation timing of the peeling member. FIG. 12: developer, 13: developing roller, 14: toner replenishing means, 15: peeling member, 16: drive unit, 17: control unit, 33: developing time drive unit, 3
4: Driving means for continuous toner supply, A: operating position, B: resting position, D: developer.

Continued Front Page (72) Hideo Yamasa 22-22 Nagaikecho, Naganocho, Abeno-ku, Osaka, Osaka (72) Inventor Seiko Mototsuka 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Prefecture Sharp Co., Ltd. (72) Inventor Tatsuya Ito, 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka, Japan Sharp Corporation (56) References: 61-76453 (JP, U)

Claims (3)

[Scope of utility model registration request] 1. A developing roller is rotatably supported in a developing tank, and a peeling member for peeling off a developer on the developing roller is provided in the vicinity of the developing roller, and the peeling member is arranged in the vicinity of the developing roller. A drive unit that is switchable between an operating position in which the developer is peeled off and agitated and a resting position in which the developer is separated from the developing roller to reduce stress on the developer, and that switches the peeling member between the operating position and the resting position; A toner replenishing unit that replenishes the developing tank with toner, and a control unit that controls the drive unit so that the peeling member is in an operating posture when toner is replenished and in a rest posture when toner is not replenished are provided. Development device. 2. A developing roller is rotatably supported in a developing tank, and a peeling member for peeling off the developer on the developing roller is provided in the vicinity of the developing roller, and the peeling member is arranged in the vicinity of the developing roller. A drive unit that is switchable between an operating position in which the developer is peeled off and agitated and a resting position in which the developer is separated from the developing roller to reduce stress on the developer, and that switches the peeling member between the operating position and the resting position; A developing device, wherein a control unit that controls the drive unit is provided with a developing-time driving unit that causes the peeling member to be in an operating posture during development and in a resting posture during non-developing. 3. A developing roller is rotatably supported in a developing tank, and a peeling member for peeling off the developer on the developing roller is provided in the vicinity of the developing roller, and the peeling member is in proximity to the developing roller. A drive unit that is switchable between an operating position in which the developer is peeled off and agitated and a resting position in which the developer is separated from the developing roller to reduce stress on the developer, and that switches the peeling member between the operating position and the resting position; Toner replenishment means for replenishing toner to the developing tank and a control section for controlling the drive section are arranged such that the peeling member is in an operating position when the toner replenishing time is a fixed time or longer, and is in a resting state when the toner replenishing time is less than the fixed time. A developing device provided with an hour driving unit.