JP3050653B2 - Cleaning equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning device for an image forming apparatus such as a copying machine, a printer, and a facsimile.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 1-259393 discloses that after a toner image formed on a latent image carrier composed of a photosensitive drum is transferred to a transfer material, toner remaining on the latent image carrier is transferred. A magnetic brush cleaning device of an image forming apparatus for cleaning with a magnetic brush of a cleaning agent magnetically carried on a cleaning means comprising a cleaning sleeve and collecting the toner on the cleaning means by a toner collecting member; A first constant current power supply insulated from the ground is connected between the collection member and the cleaning means, and a second constant current power supply is connected between the latent image carrier and the cleaning means. A magnetic brush cleaning device is described.

In this magnetic brush cleaning apparatus, a first constant current power supply insulated from the ground is connected between the toner collecting member and the cleaning means, and the first constant current power supply is connected between the latent image carrier and the cleaning means. Since the second constant current power supply is connected between them, a constant cleaning electric field is always applied between the latent image carrier and the cleaning means regardless of the level of the potential of the residual toner on the latent image carrier. Can be formed. In addition, when the resistance of the cleaning agent increases and the cleaning property deteriorates, the cleaning property is increased so that the cleaning electric field is corrected, so that the cleaning property can be maintained satisfactorily. The same applies to the scavenge bias formed between the toner collecting member and the cleaning means. Further, the first constant current power supply for forming the cleaning electric field and the second constant current power supply for forming the scavenge bias are independent of each other and do not interfere with each other. The current value of the cleaning unit between the cleaning unit and the cleaning unit, and the current value of the scavenging unit between the toner collecting member and the cleaning unit can be always kept constant.

[0004]

In the above-described magnetic brush cleaning device, a first constant current power source insulated from the ground is connected between the toner collecting member and the cleaning means, and the latent image carrier and the cleaning device are cleaned. Since the second constant current power supply is connected between the power supply and the means, when the surface potential of the photoconductor in the cleaning unit is low, the electric field for cleaning increases in conjunction with that. If the cleaning electric field is too high, charge injection from the cleaning means to the toner occurs, and a reverse toner adhesion phenomenon in which the toner adheres to the latent image carrier occurs.

It is an object of the present invention to improve the above-mentioned drawbacks and to prevent the reverse toner adhesion phenomenon by keeping the cleaning electric field below a certain value even if the surface potential of the latent image carrier is abnormally lowered for some reason. It is an object of the present invention to provide a cleaning device that can perform cleaning.

[0006]

In order to achieve the above object, the present invention forms a latent image on a latent image carrier, develops the latent image into a toner image, and transfers the toner image to a transfer material. In the cleaning device of the image forming apparatus for cleaning the residual toner on the latent image carrier after transfer, a magnetic brush is formed by carrying a cleaning agent including toner and carrier on the outer periphery, and the magnetic brush is rotated to carry the latent image. Cleaning means for electrically sucking and removing residual toner on the body by the carrier of the magnetic brush, a toner collecting member for collecting the toner removed from the latent image carrier by the cleaning means from the cleaning means, A first constant current source for applying a bias potential to the cleaning unit, and a second constant current source connected between the cleaning unit and the toner collecting member. And current sources, in which the potential difference between the cleaning means and the ground and a zener diode for limiting within a certain limit.

[0007]

The cleaning means carries a cleaning agent containing toner and carrier on the outer periphery to form a magnetic brush, and rotates to electrically attract residual toner on the latent image carrier by the magnetic brush carrier. Remove. The toner collection member collects the toner removed from the latent image carrier by the cleaning unit from the cleaning unit, and the first constant current source applies a bias potential to the cleaning unit. The second constant current source applies a bias potential to the toner collecting member, and the Zener diode limits the potential difference between the cleaning means and the ground to a certain limit.

[0008]

[0009]

FIG. 3 shows an embodiment of the present invention. This embodiment is a magnetic brush cleaning apparatus of an image forming apparatus such as a copying machine using a latent image carrier 11 made of an endless belt-shaped photosensitive member. The photoreceptor 11 is stretched over a drive roller (not shown) and other driven rollers 12 to 14, and is given a predetermined tension by a spring.

In the image forming apparatus, during the copying operation, the photoreceptor 11 is driven to rotate in the Z direction by rotating the driving roller by a motor, and a predetermined polarity, for example, a negative After being uniformly charged uniformly, it is subjected to image exposure by exposure means to form an electrostatic latent image. This electrostatic latent image is developed by a developing device to become a toner image, and is transferred by a transfer device to a transfer material composed of transfer paper fed from a paper feeding device. In this case, the electrostatic latent image becomes a toner image by attaching a toner charged to a polarity opposite to the polarity by the developing device. The transfer paper is separated from the photoreceptor 11 after the transfer of the toner image, the toner image is fixed by a fixing device, and is discharged as a copy. After the transfer paper is separated from the photoreceptor 11, the residual toner is removed by the magnetic brush cleaning device 15 of the present embodiment, the charge is removed by the charge remover, and the photosensitive member 11 can be reused.

[0011] Magnetic brush cleaning device 1 of the present embodiment
In 5, a cleaning opposing roller 16 is disposed on the back surface side of the photoconductor 11, and a cleaning unit 17 including a cleaning sleeve is disposed opposite the cleaning opposing roller 16 with the photoconductor 11 interposed therebetween. Both ends of the cleaning opposing roller 16 are movably supported, and are pressed against the photoconductor 11 by a leaf spring 24. The cleaning sleeve 17 is driven to rotate counterclockwise by a driving mechanism, and a plurality of magnets 18 are disposed inside. A cleaning agent 19 containing a toner and a carrier is carried on the outer periphery of the cleaning sleeve 17 by the magnetic force of a magnet 18 to form a magnetic brush. The photoconductor 11 is guided by the cleaning opposing roller 16, and a predetermined gap is formed between the photoconductor 11 and the cleaning sleeve 17.

A cleaning sleeve 17 has a photoconductor 11 on it.
A bias potential having a polarity (negative polarity) opposite to the charging polarity of the upper residual toner T is applied from a power supply, and the carrier in the cleaning agent 19 is charged to a negative polarity. The cleaning agent 1 accompanying the rotation of the cleaning sleeve 17
The carrier is also negatively charged by frictional charging between the toner 9 and the carrier. The magnetic brush composed of the cleaning agent 19 carried on the cleaning sleeve 17 is conveyed in accordance with the rotation of the cleaning sleeve 17 and is regulated to a predetermined layer thickness by the regulating member 20, and the residual toner T on the photoreceptor 11 has a polarity opposite to that of the toner. (Cleaning) while electrically suctioning with a carrier. The residual toner removed from the photoconductor 11 adheres to the carrier of the cleaning agent 19, is conveyed along with the rotation of the cleaning sleeve 17, and is collected by the toner collecting roller 21. Here, the toner collecting roller 21 is a metal core 2 having conductivity.
1a is covered with an outer layer 21b made of a dielectric, has a predetermined gap between itself and the cleaning sleeve 17, and is rotationally driven by a driving mechanism. A bias potential having a polarity opposite to the polarity of the charged toner is applied to the metal core 21 a from a power supply, and a part of the toner in the cleaning agent 19 is electrically sucked by the toner collecting roller 21. The toner on the toner collecting roller 21 is scraped off from the toner collecting roller 21 by the blade 22, and is conveyed outside the machine by the auger spring 23.

[0013] Figure 1 shows a circuit arrangement of this embodiment, FIG. 2
Shows the timing chart. In FIG. 1, the resistance R ₁ is the toner collection roller 21 and the cleaning sleeve 1.
7 shows the resistance of the cleaning agent 19 existing between the cleaning agent 19 and the cleaning agent 19.
The photoreceptor 11 is obtained by laminating a conductive layer and an organic photoreceptor layer on a photoreceptor base material and providing a conductive paint layer on both ends of the conductive layer, and the conductive paint layer is grounded. The resistance R ₂ indicates the resistance of the cleaning agent 19 existing between the cleaning sleeve 17 and the photoconductor 11, and the resistance R ₃ indicates the resistance of the photoconductor 11 (the resistance of the conductive layer, the organic photoconductor layer and the conductive paint layer). Show. PG is a cleaning sleeve 17
3 shows a gap between the photoconductor 11 and the photoconductor 11. A power supply 28 composed of a constant current source is connected between the metal core 21a of the toner collecting roller 21 and the cleaning sleeve 17 and is insulated from the ground (ground or copier frame). Is being applied. A power supply 29 composed of a constant current source is connected between the cleaning sleeve 17 and the ground, and applies a bias potential to the cleaning sleeve 17. Potential difference limiting means 30 composed of a bidirectional Zener diode is connected between the cleaning sleeve 17 and the ground, and limits the potential difference between the cleaning sleeve 17 and the ground to a certain limit.
i ₁ indicates a current supplied from the constant current source 28, and i ₂ indicates a current supplied from the constant current source 29. The i ₂ zener whole when not in operation of the diode 30 flows through the resistor R ₃ of the resistor R ₂ and the photosensitive member 11 of the cleaning agent 19, the resistance of the resistor R ₂ and the photosensitive member 11 of the cleaning agent 19 during operation of the Zener diode 30 Current i ₃ flowing through R ₃ and current i ₄ flowing through zener diode 30
Divided into

[0014] When the current i ₂ flows through the resistor R ₃ of the resistor R ₂ and the photosensitive member 11 of the cleaning agent 19 from the constant current source 29, cause a voltage drop V _1, the voltage drop V ₁ was V ₁ = (R ₂ + R ₃ ) i ₂ . Operating voltage (Zener voltage) V ₂ of the Zener diode 30, the voltage drop V ₁ is set slightly smaller than the value V ₀ which is the time limit that the toner adheres from the magnetic brush on the cleaning sleeve 17 to the photoreceptor 11. Therefore, when V ₁ <V ₂ , i ₃ = i ₂ . But V
_{When 1} ≧ V ₂ , the current i ₄
Flows, and i ₂ = i ₃ + i ₄ . Therefore, the maximum value of V ₁ was limited to the operating voltage V ₂ of the Zener diode 30 as shown in solid lines in FIG. 2, not greater than the operating voltage V ₂ of the Zener diode 30 as shown in dotted lines in FIG. 2. For this reason,
An abnormal increase in the potential of the cleaning sleeve 17 is suppressed.

Normally, before the residual toner on the photoconductor 11 is removed by the cleaning device 15, the cleaning electric field due to the difference between the surface potential of the photoconductor 11 and the potential of the cleaning sleeve 17 is constant. However, when the surface potential of the photoconductor 11 drops abnormally for some reason, the potential of the cleaning sleeve 17 does not follow the reduction of the surface potential of the photoconductor 11 and the operating voltage V _{2 of the} zener diode 30 is not increased.
And the reverse toner adhesion phenomenon in which toner adheres to the photoconductor 11 from the magnetic brush on the cleaning sleeve 17 is eliminated. Note that the level of the potential in the above description is a story based on an absolute value, and the potential of + is not high and the potential of-is not low.

[0016]

As described above, according to the first aspect of the present invention,
An image forming apparatus for forming a latent image on a latent image carrier, developing the latent image into a toner image, transferring the toner image to a transfer material, and cleaning residual toner on the latent image carrier. In the device, toner and
Forming magnetic brush by carrying cleaning agent including rear
And the residual toner on the latent image bearing member by rotating magnetic
A cleaning means for electrically sucking and removing the toner with a brush carrier; and a cleaning means for removing the toner removed from the latent image carrier by the cleaning means.
A toner collecting member for al recovery, a first constant current source providing a bias voltage to said cleaning means, said Kleene
Second means connected between the toner collecting means and the toner collecting means.
And a Zener diode for limiting the potential difference between the cleaning means and the ground to within a certain limit, so that the surface potential of the latent image carrier may be abnormally lowered for some reason. In addition, the cleaning electric field can be suppressed to a certain value or less to prevent the reverse toner adhesion phenomenon , and the configuration is simplified, and the cost is reduced.
You.

[0017]

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a circuit configuration of an embodiment of the present invention.

FIG. 2 is a timing chart of the embodiment.

FIG. 3 is a sectional view showing a configuration of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Photoconductor 17 Cleaning sleeve 19 Cleaning agent 21 Toner collection roller 29 Constant current source 30 Zener diode

Claims (1)

(57) [Claims] 1. A latent image is formed on a latent image carrier, and the latent image is developed into a toner image. After the toner image is transferred to a transfer material, residual toner on the latent image carrier is cleaned. In a cleaning device of an image forming apparatus, a magnetic brush is formed by carrying a cleaning agent including a toner and a carrier on an outer circumference, and the toner is rotated to electrically remove residual toner on the latent image carrier by a carrier of the magnetic brush. Cleaning means for sucking and removing, a toner recovery member for recovering the toner removed from the latent image carrier by the cleaning means from the cleaning means, a first constant current source for applying a bias potential to the cleaning means; ,
A second constant current source connected between the cleaning unit and the toner collecting member; and a zener diode for limiting a potential difference between the cleaning unit and the ground to a certain limit. Cleaning equipment.