JPH07177328A - Developing device - Google Patents

Abstract

PURPOSE:To prolong the life of a developing device by preventing the adhesion of toner to a doctor blade. CONSTITUTION:Toner is frictionally charged with static electricity by sliding a doctor blade 16 around a developing roller 14, and when an electrostatic latent image on a photosensitive belt 1 is closed to the toner, the toner is scattered and stuck to the latent image. A scraper 17 formed of an insulating material such as polyurethane is arranged on the downstream side lower than a position opposed to the belt 1 and toner on the roller 14 which is not stuck to the belt 1 is scraped by the scraper 17 and recovered to a toner recovering case 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device in an electrophotographic recording type image forming apparatus, and more particularly to a developing device for charging toner by a friction charging method.

[0002]

2. Description of the Related Art FIG. 10 shows a conventional developing device 4.
The toner supplied from the toner supply tank 12 is conveyed to the developing roller 14 while being stirred by the agitator 13. The surface of the developing roller 14 is magnetized in advance, and toner having a metal component is attracted to the surface of the developing roller 14. This toner is used by the developing roller 14 and the doctor blade 1.
When 6 comes into sliding contact, it is triboelectrically charged, and when an electrostatic latent image on a photoreceptor (not shown) approaches, it flies and adheres to the electrostatic latent image. Further, the toner on the developing roller 14 which has not adhered to the photoconductor is eliminated by the static elimination brush 15 slidingly contacting it. As a developing device of this type, for example, FEED (Floa
ting Electrode Effect Development) method and μ-IS
The P method is known, and the μ-ISP method is widely used because it is a low-cost one-component development.

[0003]

However, in such a developing device, the developing roller 14 rotates at a high speed and comes into sliding contact with the doctor blade 16, so that the toner on the developing roller 14 that did not fly to the photosensitive member is melted. Then, the doctor blade 16 is wound up and fixed to the doctor blade 16, and the doctor blade 16 that has been fixed prevents the toner from adhering to the developing roller 14 and causes image unevenness called white spots in the image. When such a state occurs, the developing device reaches the end of its life and must be replaced, so that the running cost per sheet of recording paper becomes high.

In view of the above conventional problems, it is an object of the present invention to provide a developing device capable of preventing toner from sticking to a doctor blade and prolonging its life.

[0005]

In order to achieve the above object, the first means is a developing device for frictionally charging toner by a doctor blade slidingly contacting a developing roller and adhering the toner to a photoconductor. An insulating scraper for scraping off the residual toner by coming into contact with the developing roller is provided downstream of the adhesion position of the developing roller and the photoconductor.

A second means is provided with a control means in the first means, which brings the insulating scraper into contact with the developing roller at the start of development and separates the insulating scraper from the developing roller at the end of development. It is characterized by that.

A third means is characterized in that, in the second means, the control means detects that the recording paper is discharged and separates the insulating scraper from the developing roller.

A fourth means is characterized in that, in the second means, the control means causes the timer means to bring the insulating scraper into contact with the developing roller, and then to separate the insulating roller.

A fifth means is characterized in that, in the second means, the control means brings the insulating scraper into contact with the developing roller at the start of recording an image received by facsimile.

A sixth means is provided with a toner circulating means for collecting the toner scraped off by the insulating scraper in the first means and supplying the toner to the developing roller.

[0011]

According to the first means, after the doctor blade is brought into sliding contact with the developing roller to adhere the triboelectrically charged toner to the photoconductor, the residual toner on the developing roller is scraped off by the insulating scraper, so that the photoconductor flies to the photoconductor. It is possible to prevent the undesired toner on the developing roller from being melted and rolled up and fixed to the doctor blade, so that the life can be extended.

In the second means, the insulating scraper abuts the developing roller at the start of development and separates from the developing roller at the end of development. Therefore, it is possible to prevent the insulating scraper and the developing roller from being worn. The life can be extended.

In the third means, since the insulating scraper is separated from the developing roller upon detecting that the recording paper is discharged, it is possible to prevent the insulating scraper and the developing roller from being worn away. , The life can be extended.

In the fourth means, the insulating scraper is brought into contact with and separated from the developing roller by the timer means, so that it is possible to prevent the insulating scraper and the developing roller from being worn, and therefore the life is extended. can do.

In the fifth means, since the insulating scraper contacts the developing roller at the start of recording the image received by the facsimile, it is possible to prevent the insulating scraper and the developing roller from being worn, and the plain paper facsimile. The running cost per piece of receiving paper can be reduced in the apparatus.

In the sixth means, the toner scraped off by the insulating scraper is re-supplied to the developing roller, so that the toner consumption amount can be reduced and therefore the running cost can be reduced.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a block diagram showing an embodiment of a developing device according to the present invention, FIG. 2 is a block diagram showing a facsimile device equipped with the developing device of FIG. 1, and FIG. 3 is an image forming section of the facsimile device of FIG. FIG. 4 is a configuration diagram showing a drive mechanism of the developing roller of FIG.

First, a facsimile apparatus equipped with the developing device of this embodiment will be described with reference to FIG. The reading unit is a reading scanning unit 101 that scans a transmission document or a copy document.
A reading processing unit 102 for processing an image signal read by the reading scanning unit 101; and a reading processing unit 1
A line memory 103 for temporarily storing the image data processed by 02 and a line memory control unit 104.

The transmission image data stored in the line memory 103 is read out under the control of the line memory control unit 104, the redundancy is removed according to the mode of the compression unit of the information compression unit and the decompression unit 105, and the data bus It is stored in the RAM 107 via 106. The RAM 107 is used as a transmission buffer, and the image data read from the RAM 107 is sent to the modem 109 via the communication control unit 108 to be modulated and sent to the line via the network control unit 110.

On the other hand, the image data received from the line is sent to the modem 109 via the network control unit 110 and demodulated, and stored in the RAM 107 via the communication control unit 108 and the data bus 106. The RAM 107 is used as a reception buffer, and the image data read from the RAM 107 is sent to the information compression unit and the decompression unit of the decompression unit 105 via the data bus 106 to be decompressed, and then the recording processing unit via the line memory 103. 111, the image is sent to the recording scanning unit (image forming unit) 112 of the electrophotographic recording system as shown in detail in FIG. 3 and the received image is recorded on the recording paper.

Regarding the image information, the network controller 110
And the communication control information is read by the communication control unit 108 to perform transmission control and error correction, and the journal information is stored in the RAM 107 when necessary. A call signal necessary for network control is sent to the line by the network control unit 110, and image information that does not require compression or decompression of information is read by the reading processing unit 102 and the line memory 103.
Is directly output to the RAM 107 or the outside through the data bus 106 to perform image processing and image communication.

It is also possible to directly input image-processed information or image-synthesized information, or to superimpose the information on the document image information and record / reproduce it via the line memory 103. . The line memory 103 can be used separately from the information compression unit and decompression unit 105, and compressed information can be decompressed and recorded via the line memory 103 irrespective of reading scan or recording scan. .

The control of the entire system, the management of the information flow, the communication control, and the network control are performed based on the program stored in the ROM 114.
It is carried out comprehensively by 3. The main system controls are the man-machine interface by the panel unit 115 and the reading units 101, 102 by the mechanism control unit 116.
And control of the mechanical configuration of the recording units 111 and 112. In the panel unit 115, the number of input / output terminals and control method are determined according to the type and format of panel switch and panel display.
Further, the mechanism control unit 116 determines the type and quantity of drivers and sensors according to the method and mechanical configuration of the reading units 101 and 102 and the recording units 111 and 112, and as a result, M
The control of the PU 113 has been decided.

Next, the image forming section (recording scanning section) 112 will be described with reference to FIG. First, the photoconductor belt 1 is precharged by the charger 2, and then an electrostatic latent image is formed by optical writing by the exposure unit 3. Then, toner is attached to this electrostatic latent image by the developing device 4 of this embodiment to form a toner image. Recording paper 5 in the paper cassette
Is conveyed so as to coincide with the toner image on the photosensitive belt 1 and the toner image is transferred by the transfer device 6, then conveyed between the fixing roller 8 and the pressure roller 7 to fix the toner image, and then discharged. The paper sensor 11 detects and ejects the paper. Further, the toner remaining on the photosensitive belt 1 after the transfer is scraped off by the waste toner cartridge 9 and collected as waste toner, and the residual charge is eliminated by the charge removing LED 10.
The static electricity is removed by irradiating with light.

In the developing device 4, as shown in FIG. 1, the toner replenished from the toner replenishing tank 12 (see FIG. 10) is conveyed to the developing roller 14 while being agitated by the agitator 13. The surface of the developing roller 14 is magnetized in advance, and toner having a metal component is attracted to the surface of the developing roller 14. This toner is triboelectrically charged when the developing roller 14 and the doctor blade 16 are in sliding contact with each other, and when the electrostatic latent image on the photosensitive belt 1 approaches, it flies and adheres to the electrostatic latent image. As shown in FIG. 4, the shaft of the developing roller 14 is connected to a motor shaft 16 provided on the facsimile apparatus main body side via a belt 16a and a gear 16b, and the rotation of the motor shaft 16 is transmitted to collect toner. It is frictionally charged.

In this embodiment, a scraper 17 made of an insulating material such as polyurethane is fixedly arranged downstream of the position facing the photoconductor belt 1 and attached to the photoconductor belt 1. The toner remaining on the developing roller 14 is scraped off by the scraper 17 and collected in the toner collecting container 18. After that, the developing roller 14 is discharged by the discharging brush 15 slidingly contacting it. Therefore, according to this embodiment, the toner on the developing roller 14 that did not adhere to the photosensitive belt 1 is scraped off by the scraper 17, and the toner collecting container 1
The toner is collected in 8
Can be prevented from sticking to and the life can be increased.

Next, a second embodiment will be described with reference to FIG. Although the scraper 17 is fixedly arranged in the above-described embodiment, in the second embodiment, the scraper 17 is supported by the scraper holder 19, and the scraper holder 19 contacts the scraper 17 with the developing roller 14. Alternatively, the solenoid 20 is swingable around a fulcrum provided on the toner collection container 18 so as to be separated from each other. Since the other configurations are the same, detailed description thereof will be omitted.

In such a structure, for example, in a facsimile machine, after receiving image information, the solenoid 20 is driven by the control of the CPU 113 so that the scraper 17 contacts the developing roller 14 at the start of the recording operation, and the sheet is discharged. When the sensor 11 detects the discharge of the recording paper 5, the solenoid 20 is driven so that the scraper 17 is separated from the developing roller 14. Therefore, the scraper 17 does not always come into contact with the developing roller 14, so that the scraper 17 and the developing roller 14 can be prevented from being deformed, and the life can be extended.

FIG. 6 shows a third embodiment. In the second embodiment, the scraper 17 is separated from the developing roller 14 when the discharge sensor 11 detects the discharge of the recording paper 5, but in the third embodiment, the development is finished by the timer 113a. The scraper 17 is controlled so as to separate from the developing roller 14 by measuring the time. Therefore, also in this embodiment, the scraper 17 is not always in contact with the developing roller 14, so that the scraper 17 and the developing roller 14 can be prevented from being deformed, and the life can be increased.

FIG. 7 shows a fourth embodiment. In this embodiment, the toner scraped off by the scraper 17 is returned to the inside of the developing device 4 by the toner carrying screw 22 via the toner carrying path 21. There is. Therefore, the toner can be circulated and reused, so that the toner consumption amount can be reduced and the running cost can be reduced.

The fifth embodiment shown in FIG. 8 shows an example in which the fourth embodiment and the second embodiment are combined. That is, first, similarly to the second embodiment, the solenoid 20 is driven by the control of the CPU 113 so that the scraper 17 contacts the developing roller 14 at the start of the recording operation, and the discharge sensor 11 discharges the recording paper 5. When is detected, the solenoid 20 is driven so that the scraper 17 is separated from the developing roller 14. And scraper 17
The toner scraped off by the toner is returned to the inside of the developing device 4 by the toner carrying screw 22 via the toner carrying path 21.

The sixth embodiment shown in FIG. 9 shows an example in which the fourth embodiment and the third embodiment are combined. That is, first, as in the third embodiment, the solenoid 20 is driven by the control of the CPU 113 so that the scraper 17 contacts the developing roller 14 at the start of the recording operation, and the timer 113a measures the time when the development is completed. Then, the solenoid 20 is driven so that the scraper 17 is separated from the developing roller 14. And scraper 1
The toner scraped off by 7 returns to the inside of the developing device 4 by the toner carrying screw 22 via the toner carrying path 21.

[0033]

As described above, according to the first aspect of the invention, after the doctor blade is brought into sliding contact with the developing roller and the toner charged by friction is adhered to the photoconductor, the residual toner on the developing roller is removed by the insulating scraper. It will be scraped off,
It is possible to prevent the toner on the developing roller that did not fly to the photosensitive member from being melted and rolled up and fixed to the doctor blade, and therefore the life can be extended.

According to the second aspect of the present invention, the insulating scraper abuts the developing roller at the start of development and separates from the developing roller at the end of development, so that it is possible to prevent the insulating scraper and the developing roller from being worn. Therefore, the life can be extended.

According to the third aspect of the present invention, since the insulating scraper is separated from the developing roller by detecting that the recording paper is discharged, it is possible to prevent the insulating scraper and the developing roller from being worn. Therefore, the life can be extended.

According to the fourth aspect of the present invention, since the insulating scraper is brought into contact with and separated from the developing roller by the timer means, it is possible to prevent the insulating scraper and the developing roller from being worn, and therefore the life of the insulating scraper is reduced. Can be lengthened.

According to the fifth aspect of the present invention, the insulating scraper abuts the developing roller when the recording of the image received by the facsimile is started. Therefore, it is possible to prevent the insulating scraper and the developing roller from being worn. In the paper facsimile machine, the running cost per sheet of received paper can be reduced.

In the invention described in claim 6, since the toner scraped off by the insulating scraper is re-supplied to the developing roller, the toner consumption amount can be reduced, and therefore the running cost can be reduced. it can.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a developing device according to the present invention.

FIG. 2 is a block diagram showing a facsimile device including the developing device of FIG.

FIG. 3 is a configuration diagram showing an image forming unit of the facsimile apparatus of FIG.

FIG. 4 is a configuration diagram showing a drive mechanism of the developing roller of FIG.

FIG. 5 is a configuration diagram illustrating a developing device according to a second embodiment.

FIG. 6 is a configuration diagram illustrating a developing device according to a third embodiment.

FIG. 7 is a configuration diagram illustrating a developing device according to a fourth embodiment.

FIG. 8 is a configuration diagram showing a developing device of a fifth embodiment.

FIG. 9 is a configuration diagram showing a developing device of a sixth embodiment.

FIG. 10 is a configuration diagram showing a conventional developing device.

[Explanation of symbols]

 11 Paper Discharge Sensor 14 Developing Roller 16 Doctor Blade 17 Scraper 18 Toner Collection Container 19 Scraper Holder 20 Solenoid 21 Toner Conveying Path 22 Toner Conveying Screw 113 CPU (MPU) 113a Timer

Claims (6)

[Claims] 1. A developing device for frictionally charging a toner by a doctor blade slidingly contacting the developing roller to attach the toner to a photoconductor, the developing device being provided on a downstream side of the attaching position of the developing roller and the photoconductor. A developing device, which is provided with an insulating scraper for contacting with and scraping off the residual toner. 2. A control means for bringing the insulating scraper into contact with the developing roller at the start of development and separating the insulating scraper from the developing roller at the end of development. Item 1. The developing device according to item 1. 3. The developing device according to claim 2, wherein the control unit detects that the recording paper is discharged and separates the insulating scraper from the developing roller. 4. The control means, after contacting the insulating scraper with the developing roller by a timer means,
The developing device according to claim 2, wherein the developing devices are separated from each other. 5. The developing device according to claim 2, wherein the control unit brings the insulating scraper into contact with the developing roller when recording of an image received by facsimile is started. 6. A toner circulating means for collecting the toner scraped off by the insulating scraper and supplying the collected toner to the developing roller.
The developing device described.