JPH08123196A - Developing device used in common with cleaning - Google Patents

Abstract

PURPOSE: To provide a developing device used in common with cleaning, capable of sufficient cleaning without reducing an image forming speed, at a low cost. CONSTITUTION: The developing device used in common with cleaning 10 is provided with at least two rollers 11 and 12 arranged to face a photoreceptor 1 and uses a two-component developer, the roller arranged on the upstream side in the rotational direction of the photoreceptor 1 is of the cleaning roller 11 cleaning the photoreceptor 1 and the roller arranged a part nearer to the downstream side than the cleaning roller 11 in the rotational direction of the photoreceptor 1 is of the developing roller 12 developing an electrostatic latent image on the photoreceptor 1 with the two-component developer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning / developing device using a two-component developer.

[0002]

2. Description of the Related Art An electrostatic latent image is developed by the first rotation of a photoconductor,
A cleaning / developing device of a cleaning / development alternating system in which the photoconductor is cleaned by the second rotation of the photoconductor is well known.

In a developing device of the magnetic brush system, a system is also known in which the toner on the photosensitive member is scraped off and developed at the same time by the scraping force of the magnetic brush of the developing device.

[0004]

The alternating developing and cleaning method described above has a problem that the image forming speed is lowered because the developing step and the cleaning step cannot be performed at the same time. Further, since an image larger than the outer peripheral area of the photoconductor cannot be formed, there is a problem that the photoconductor becomes large and the cost becomes high.

The magnetic brush method has a problem in that sufficient cleaning cannot be performed because cleaning is performed only by the scraping force of the magnetic brush.

It is therefore an object of the present invention to provide a cleaning / developing device which does not reduce the image forming speed, is small and inexpensive, and can perform sufficient cleaning.

[0007]

According to the first aspect of the present invention,
A developing device for cleaning and using two-component developer, comprising at least two rollers arranged facing the photoconductor, wherein the roller arranged upstream of the rotation direction of the photoconductor is a photosensitive member. A cleaning roller for cleaning the body, and a roller arranged downstream of the cleaning roller with respect to the rotation direction of the photoconductor develops an electrostatic latent image on the photoconductor with the two-component developer. Is characterized in that.

According to a second aspect of the present invention, in the cleaning / developing device according to the first aspect, the gap between the cleaning roller and the photoconductor is narrower than the gap between the developing roller and the photoconductor. It is characterized by having done.

According to a third aspect of the present invention, in the cleaning / development device according to the first or second aspect, the bias voltage applied to the cleaning roller is set higher than the bias voltage applied to the developing roller. To do.

According to a fourth aspect of the present invention, in the cleaning / developing device according to the first, second or third aspect, the polarity of the bias voltage applied to the cleaning roller is the polarity of the developing bias voltage applied to the developing roller. It is characterized by the opposite polarity.

The invention according to claim 5 is the invention as defined in claims 1, 2, and 3.
Alternatively, in the cleaning / development device according to the fourth aspect, the bias current applied to the cleaning roller is a combination of DC and AC or DC and pulse bias.

The invention according to claim 6 is the invention according to claim 1, 2,
The cleaning / development device described in 3, 4, or 5 is characterized in that the rotation speed of the cleaning roller is higher than the rotation speed of the development roller.

The invention according to claim 7 is based on claim 1,
In the cleaning and developing device described in 3, 4, 5 or 6, the rotation direction of the cleaning roller is the same as the rotation direction of the photoconductor, and the rotation direction of the development roller is opposite to the rotation direction of the photoconductor. Is characterized in that.

[0014]

According to the first aspect of the present invention, the developing roller develops the electrostatic latent image with the two-component developer while the surface of the photoconductor on which the electrostatic latent image is formed is cleaned by the cleaning roller.

According to the second aspect of the present invention, the cleaning roller having a gap between the developing roller and the photoconductor, which is narrower than the gap between the developing roller and the photoconductor, cleans the surface of the photoconductor, while the developing roller has two components. Develop the electrostatic latent image with a developer.

According to the third aspect of the present invention, the developing roller cleans the surface of the photoconductor with a bias voltage higher than the bias voltage applied to the developing roller, and the developing roller uses a two-component developer to form an electrostatic latent image. Develop the image.

According to another aspect of the present invention, the cleaning roller, to which a bias voltage having a polarity opposite to that of the bias voltage applied to the developing roller is applied, cleans the surface of the photoconductor, while the developing roller is a two-component developer. To develop the electrostatic latent image.

According to the fifth aspect of the invention, the cleaning roller to which a bias current in which a direct current and an alternating current or a direct current and a pulse bias are superposed is applied cleans the surface of the photosensitive member, while the developing roller uses a two-component developer. Develop the latent image.

According to the sixth aspect of the invention, the developing roller develops the electrostatic latent image with the two-component developer while the cleaning roller having a rotational speed higher than that of the developing roller cleans the surface of the photoconductor.

According to the seventh aspect of the present invention, the cleaning roller that rotates in the same direction as the rotation direction of the photoconductor cleans the surface of the photoconductor and the developing roller that rotates in the opposite direction to the rotation direction of the photoconductor. The electrostatic latent image is developed with a two-component developer.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 represents a photoconductor, and reference numeral 10 represents a cleaning and developing device.

Around the photoconductor 1, a charger 2 for uniformly charging the surface of the photoconductor 1, an exposing means 3 for forming an electrostatic latent image on the surface of the photoconductor 1, and a charge for a non-image portion are erased. The eraser 4 and the cleaning / development device 10 that cleans the photoconductor 1 and develops the electrostatic latent image on the photoconductor 1 with a two-component developer to form a toner image, and electrostatically attaches the toner to the photoconductor 1. A pre-transfer exposure device 7 that weakens the adhesion force, a transfer belt 5 that transfers the toner image on the photoconductor 1 to the transfer paper P and conveys it, and a discharge lamp 6 that erases the electric charge remaining on the photoconductor 1 are arranged in this order. There is.

The cleaning / development device 10 is arranged so as to face the photoconductor 1, and is arranged downstream of the cleaning roller 11 with respect to the cleaning roller 11 for cleaning the photoconductor 1 and the rotation direction of the photoconductor 1. , A developing roller 12 for developing the electrostatic latent image on the photoconductor 1, and a stirring paddle 13 for supplying toner to the developing roller 12 while stirring.
A developing blade 20 for regulating the thickness of the toner supplied to the developing roller 12, a second feeding roller 14 for feeding the toner to the stirring paddle 13, and a first feeding roller 15 for feeding the toner to the second feeding roller 14. A rotary member 16 for supplying toner to the first feed roller 15, a blade 17 for scraping the toner collected by the cleaning roller 11, and a toner scraped by the blade 17 for the second feed roller 1 again.
4, a separator 18 for sending the toner to the sheet 4, a screw 19 for carrying the toner sent by the separator 18, and a casing for housing these members.

The photosensitive member 1 is rotationally driven in the direction of the arrow at a speed vp, the cleaning roller 11 at a speed vs1, and the developing roller 12 at a speed vs2.

As shown in FIG. 2, the blade 17 projects a part of the casing toward the cleaning roller 11,
It is formed integrally with the casing. The gap GD between the blade 17 and the cleaning roller 11 is equal to
And a gap GP2 between the developing roller 12 and the developing roller 12 are set to be substantially equal to each other. On the other hand, the gap GP1 between the photoconductor 1 and the cleaning roller 11 is set smaller than the gap GP2. This means that the cleaning roller 11
This is to increase the cleaning power by increasing the scraping force by the. Generally, the gap GP2 is 0.7-2.
mm, the rotation speed vs2 of the developing roller 12 is vp
(1.2 to 3) mm / sec, respectively.

More than the rotation speed vs2 of the developing roller 12
Increase the rotation speed vs1 of the cleaning roller 12,
Toner is accumulated between the photoconductor 1 and the cleaning roller 11 and turbulence of the toner flow is generated, so that the scraping force of the cleaning roller 11 is increased.

Further, in this example, the cleaning roller 1
The cleaning roller 11 prevents the electrostatic latent image on the photoconductor 1 from being developed by the cleaning roller 11 by increasing the electric field absorption of the toner remaining on the photoconductor 1 by the cleaning roller 11.
Bias voltage DCVB1 applied to the developing roller 12
It is set to be larger than the bias voltage DCVB2 applied to the. The bias voltage DCVB2 is, for example, the photoconductor 1
Is formed by OPC and its potential is -800V,
It is set to about -300V to 400V.

The toner remaining on the photoreceptor 1 after transfer is
The charging device 2 charges the charging polarity side, that is, the remaining toner to a polarity opposite to the polarity of the toner supplied by the developing roller 12. Therefore, a bias voltage having a polarity opposite to that of the bias voltage applied to the developing roller 12 is applied to the cleaning roller 11. This helps increase the cleaning power due to the electric field force. Incidentally, in N / P development such as digital one, the cleaning roller 1
It is not necessary that the bias voltage applied to 1 and that applied to the developing roller 12 have opposite polarities.

Further, an alternating current AC is superposed on the bias voltage DCVB1 applied to the cleaning roller 11 to generate alternating bias, which vibrates the toner on the photoconductor 1 to increase the adhesive force between the photoconductor 1 and the toner. Weakened to improve cleaning performance. In addition, the bias voltage DCVB1
Further, a pulse bias may be superimposed. The alternating bias is DC for vp-p: 1200V, 2KHZ.
It is superimposed on VB1.

As shown in FIG. 1, the transfer belt 5 is supported by a driving roller 8 and a driven roller 9, and is arranged so as to come into contact with the photoconductor 1 with a nip width of a certain value or more.
A transfer electrode 21 and a ground electrode 22 are provided on the inner peripheral surface of the transfer belt 5. Between the transfer belt 5 and the pre-transfer exposure device 7, a registration roller 23 that conveys the sheet p at a predetermined timing is arranged between the transfer belt 5 and the photoconductor 1, while the conveyance direction of the transfer belt 5 is set. On the downstream side,
A fixing device 24 that melts and fixes the toner image transferred onto the sheet of paper p is arranged.

The operation of the above configuration will be briefly described below. The image of the original is projected by the exposure device 3 on the surface of the photoconductor 1 whose surface is uniformly charged by the charger 2.
An electrostatic latent image is formed. The electrostatic latent image on the photoconductor 1 is erased by the eraser 4 in the non-image portion. After that, the transfer residual toner at the time of the previous image formation is scraped off by the cleaning roller 11 of the cleaning / developing device 10, and the surface of the photoconductor 1 is cleaned.

At this time, the cleaning roller 11 is rotating faster than the rotation speed vs2 of the developing roller 12.
On the cleaning roller 11, a bias voltage DCVB1 that is higher than the bias voltage DCVB2 applied to the developing roller 12 and that has a reverse polarity and an alternating current AC are superimposed, and alternating bias is generated. Therefore, the toner on the photoconductor 1 is vibrated, and the adhesive force between the photoconductor 1 and the toner is weakened, and the toner is accumulated between the photoconductor 1 and the cleaning roller 11 or the flow of the toner is disturbed. Therefore, the scraping force of the cleaning roller 11 is increased.

The residual toner scraped off by the cleaning roller 11 is further scraped off by the blade 17, slides down on the separator 18, is transferred again to the second feed roller by the screw 19, and is again provided for development.

The electrostatic latent image on the photoconductor 1 is the developing roller 12
As a result, the toner is attached and a toner image is formed.
On the other hand, one sheet p is fed from a sheet feeding device (not shown) and sent to the registration rollers 23. The registration roller sends out the paper p to the transfer belt 5 at the timing when the toner image on the photoconductor 1 and the paper p coincide with each other on the transfer belt 5. Paper p on which the toner image has been transferred by the transfer belt 5
Is sent to the fixing device 24, heated and fixed, and then discharged to a paper discharge unit (not shown).

FIG. 3 shows a modified example. This modification is different from the examples shown in FIGS. 1 and 2 in that the developing roller 12 and the cleaning roller 11 are rotated in the same direction as the photosensitive member 1 and the blade 17 is removed to replace the developing blade 20a with the casing. Only the points provided integrally are different.

If the rotation direction of the cleaning roller 11 is the same as the rotation direction of the photoconductor 1, the relative speed difference between the photoconductor 1 and the cleaning roller 11 becomes large, and the residual toner on the photoconductor 1 by the cleaning roller 11 becomes large. The scraping power becomes stronger.

FIG. 4 shows another modification. This modification is different from the example shown in FIGS. 1 and 2 in that the cleaning roller 11 is rotated in the same direction as the photosensitive member 1 and the developing roller 12 is rotated in the opposite direction. Direction, and a blade 30 is provided instead of the blade 17 except for the above.

If the rotation direction of the cleaning roller 11 is the same as the rotation direction of the photoconductor 1, the relative speed difference between the photoconductor 1 and the cleaning roller 11 becomes large, and the residual toner on the photoconductor 1 due to the cleaning roller 11 is removed. The scraping power becomes stronger. On the other hand, when the rotation direction of the developing roller 12 is opposite to the rotation direction of the photoconductor 1, the developing roller 12
Scraping of the toner due to is reduced, and the toner can be sufficiently attached to the electrostatic latent image on the photoconductor 1.

[0039]

According to the present invention, the developing roller develops the electrostatic latent image with the two-component developer while the surface of the photosensitive member on which the electrostatic latent image is formed is cleaned by the cleaning roller. A conventional cleaning device can be omitted, an image forming speed is not reduced, and an inexpensive cleaning / developing device can be provided. Further, by reusing the residual toner, the resource is reduced.

According to the second aspect of the present invention, the cleaning roller having a gap between the developing roller and the photoconductor, which is narrower than the gap between the developing roller and the photoconductor, cleans the surface of the photoconductor, while the developing roller has two components. Since the electrostatic latent image is developed with the developer, in addition to the effect of the first aspect, the scraping force of the residual developer on the photoconductor by the cleaning roller is increased, and sufficient cleaning can be performed.

According to the third aspect of the present invention, the developing roller cleans the surface of the photoconductor with a bias voltage higher than the bias voltage applied to the developing roller, and the developing roller uses a two-component developer to form an electrostatic latent image. Since the image is developed, in addition to the effect of the first aspect, the cleaning roller attracts the developer by the electric field force and can perform sufficient cleaning.

According to the fourth aspect of the invention, the cleaning roller, to which a bias voltage having a polarity opposite to that of the bias voltage applied to the developing roller is applied, cleans the surface of the photoconductor, while the developing roller is a two-component developer. Since the electrostatic latent image is developed by the method, the cleaning roller attracts the developer on the photoconductor whose polarity is reversed by the electric field force to perform sufficient cleaning, in addition to the effect of the first aspect.

According to the fifth aspect of the present invention, the cleaning roller to which a bias current in which a direct current and an alternating current or a direct current and a pulse bias are superimposed is applied cleans the surface of the photoconductor, while the developing roller is a two-component developer. Since the electrostatic latent image is developed, in addition to the effect of the first aspect, the developer on the photoconductor is vibrated, the adhesion between the photoconductor and the developer is weakened, and sufficient cleaning can be performed.

According to the sixth aspect of the invention, the developing roller develops the electrostatic latent image with the two-component developer while the cleaning roller having a rotational speed higher than that of the developing roller cleans the surface of the photoconductor. In addition to the effects of the first aspect, the scraping force of the developer on the photoconductor by the cleaning roller is increased, and sufficient cleaning can be performed.

According to the seventh aspect of the invention, the cleaning roller which rotates in the same direction as the rotation direction of the photoconductor cleans the surface of the photoconductor, while the developing roller which rotates in the opposite direction to the rotation direction of the photoconductor is provided. Since the electrostatic latent image is developed by the two-component developer, in addition to the effect of claim 1, the relative speed difference between the photoconductor and the cleaning roller becomes large, and the scraping force of the developer on the photoconductor by the cleaning roller is increased. Can be cleaned sufficiently.

[Brief description of drawings]

FIG. 1 is a schematic side view of a main part of an image forming apparatus using a cleaning and developing device according to an embodiment of the present invention.

FIG. 2 is an enlarged side view of a main part of the cleaning and developing device shown in FIG.

FIG. 3 is an enlarged side view of a main part of a cleaning and developing device according to a modification of the present invention.

FIG. 4 is an enlarged side view of a main part of a cleaning and developing device according to still another modification of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging device 3 Exposure means 4 Eraser 5 Transfer belt 6 Electrification lamp 10 Cleaning developing device 11 Cleaning roller 12 Developing roller 13 Stirring paddle 14 First feeding roller 15 Second feeding roller 16 Rotating member 17 Blade 18 Separator 19 Screw

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location G03G 15/06 101 15/09 Z 21/10

Claims (7)

[Claims] 1. At least two members arranged to face the photoconductor.
A developing device for cleaning and using a two-component developer having a book roller, wherein the roller arranged upstream of the rotation direction of the photoconductor is a cleaning roller for cleaning the photoconductor. A cleaning / development device characterized in that a roller arranged downstream of the cleaning roller with respect to the rotating direction of the body is a developing roller for developing the electrostatic latent image on the photoconductor with the two-component developer. . 2. The cleaning / developing device according to claim 1, wherein the gap between the cleaning roller and the photoconductor is narrower than the gap between the developing roller and the photoconductor. 3. The cleaning and developing device according to claim 1, wherein the bias voltage applied to the cleaning roller is set higher than the bias voltage applied to the developing roller. 4. The cleaning / double-use cleaning apparatus according to claim 1, wherein the polarity of the bias voltage applied to the cleaning roller is opposite to the polarity of the developing bias voltage applied to the developing roller. Development device. 5. The cleaning / developing device according to claim 1, wherein the bias current applied to the cleaning roller is a combination of DC and AC or DC and pulse bias. 6. The cleaning / development developing apparatus according to claim 1, wherein the rotation speed of the cleaning roller is higher than the rotation speed of the developing roller. 7. The rotating direction of the cleaning roller is the same as the rotating direction of the photosensitive member, and the rotating direction of the developing roller is opposite to the rotating direction of the photosensitive member. 2. The cleaning / development developing device described in 2, 3, 4, 5 or 6.