JPH0862949A - Contact type electrifying device - Google Patents

Abstract

PURPOSE: To maintain cleaning performance for an electrifying roller over a long term and to perform stable electrification. CONSTITUTION: This device is provided with a contact/separate means (an arm 102a to a fixed part 102g) for allowing the electrifying roller 102 to contact with and separate from the surface of a photoreceptor 101, a cleaning roller 104 arranged at a position where it comes in contact with the roller 102 in a state where the roller 102 is separated from the photoreceptor 101 by the contact/separate means and removing toner or a foreign matter adhering to the surface of the roller 102, an auxiliary cleaning roller 105 removing the toner or the foreign matter adhering to the surface of the roller 104, a power source 107 impressing charge having a reverse polarity to that of the toner or the foreign matter adhering to the roller 102 on the roller 105, and a rubber blade 106 for removing the toner or the foreign matter adhering to the surface of the roller 105.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact type charging device for contacting a charging roller to uniformly charge a photoconductor, and more particularly, to a surface of a charging roller using a cleaning roller. The present invention relates to a contact type charging device that removes toner or foreign matter.

[0002]

2. Description of the Related Art In a conventional contact type charging device, charging is performed by bringing a charging roller into contact with a photosensitive member with a predetermined pressing force. There was the inconvenience that it adhered foreign substances and was easily soiled. Therefore, as means for solving this, "contact charging device and image forming apparatus" disclosed in JP-A-4-60660 and JP-A-3-10176.
As disclosed in "Charging Device" in Japanese Patent Publication No. 8, there is proposed a device in which a cleaning member removes toner or foreign matter adhering to the surface of the charging roller.

The "contact charging device and the image forming device" disclosed in Japanese Patent Laid-Open No. 4-60660 mentioned above is made of a material for the cleaning roller 203 for cleaning the surface of the charging roller 202 for charging the photosensitive member 201, as shown in FIG. The foreign matter on the charging roller is removed by having a triboelectric charging property of a polarity opposite to the polarity of the foreign matter adhering to the charging roller 202 in terms of the charging series with the charging roller 202.

The "charging device" disclosed in Japanese Patent Laid-Open No. 3-101768 is equipped with a cleaning member 303 for cleaning the surface of a charging roller 302 for charging the photoconductor 301, as shown in FIG. Since the cleaning member 303 is a sponge member and this sponge member is fixed to the support plate, the foreign matter adhering to the charging roller can be reliably removed at low cost. Further, the cleaning member is arranged so that the perpendicular line drawn from the rotation center of the charging roller to the mounting support plate of the cleaning member and the surface where the charging roller and the cleaning member come into contact with each other or have an appropriate gap. Therefore, even if the cleaning member is pressed against the charging roller for a long time and is repeatedly used, it is possible to prevent the cleaning member from being peeled off or torn from the mounting support surface.

[0005]

However, in Japanese Patent Application Laid-Open No. 4-60660 "contact charging device and image forming apparatus", the polarity and charge amount of the cleaning roller are controlled by frictional charging. Since the triboelectrification performance changes due to dirt and environmental changes, the cleaning performance of the charging roller deteriorates.

Further, in Japanese Patent Laid-Open No. 3-101768, "Charging Device", the sponge member for cleaning the charging roller is of a fixed type, and the contact portion is one place,
Since the amount of toner impregnated becomes small, there is a problem that the cleaning life becomes short. Further, there is a problem in that the charging performance may become unstable because the charging roller may be damaged, the sponge member may be peeled off, or torn off over time.

The present invention has been made in view of the above, and it is an object of the present invention to maintain the charging roller cleaning property for a long period of time and to perform stable charging.

[0008]

In order to achieve the above-mentioned object, the present invention provides a contact type charging device according to claim 1, wherein a contact type charging roller for charging a photoconductor and said charging roller are photoconductors. And a contacting / separating means for contacting / separating from the surface of the charging roller, and the charging / discharging roller is arranged at a position where the charging roller is in contact with the charging roller in a state where the charging roller is separated from the photoconductor, and is attached to the surface of the charging roller A cleaning roller for removing toner or foreign matter, an auxiliary cleaning roller formed of a conductive material for removing toner or foreign matter adhering to the surface of the cleaning roller, and a toner or foreign matter adhering to the charging roller. Charge applying means for applying charges of opposite polarity to the auxiliary cleaning roller, and toner or foreign matter adhered to the surface of the auxiliary cleaning roller It is obtained by and a removal means for removed by.

The contact type charging device according to claim 2 is
The removing means is a rubber blade, and the surface roughness of the auxiliary cleaning roller is 6.3 S or more.

Further, the contact type charging device according to claim 3 is
The cleaning roller is made of a conductive material.

Further, the contact type charging device according to claim 4 is
The cleaning roller is in an electrically floating state.

Further, the contact type charging device according to claim 5 is,
The contacting / separating unit separates the charging roller from the surface of the photoconductor immediately after the copying operation is completed, and the cleaning roller cleans the charging roller when the contacting / separating unit separates the charging roller from the photoconductor. Is to do.

The contact type charging device according to claim 6 is
At least one of the charging roller, the cleaning roller and the auxiliary cleaning roller is directly driven to rotate, and the remaining rollers are driven to be connected by a gear or the like.

[0014]

According to the contact type charging device of the present invention (claim 1), when the charging roller is separated from the photosensitive member by the contacting / separating means, the cleaning roller is disposed at the position where the charging roller contacts the charging roller. The toner or foreign matter adhering to the surface is removed, and an electric charge having a polarity opposite to that of the toner or foreign matter adhering to the charging roller is removed by the charge applying means.
It is applied to an auxiliary cleaning roller made of a conductive material, and the auxiliary cleaning roller removes toner or foreign matter adhering to the surface of the cleaning roller,
By removing the toner or foreign matter adhering to the surface of the auxiliary cleaning roller by the removing means, the surface of the cleaning roller is always kept clean.

In the contact type charging device of the present invention (claim 2), the removing means is a rubber blade, and the surface roughness of the auxiliary cleaning roller is 6.3 S or more. The surface properties of
The ability of the blade to scrape toner or foreign matter is improved.

Also, in the contact type charging device of the present invention (claim 3), the cleaning roller is charged to the same polarity by applying a charge to the auxiliary cleaning roller by using a conductive material for the cleaning roller. It

Further, the contact type charging device of the present invention (claim 4) prevents the electric charge from flowing by electrically floating the cleaning roller.

In the contact type charging device of the present invention (claim 5), the charging roller is separated from the surface of the photoconductor by the contacting / separating means immediately after the copying operation is completed, and the charging roller is separated from the photoconductor by the cleaning roller. By cleaning the charging roller when separated from each other, it is possible to prevent the toner from being left on the charging roller for a long time after the copying operation and being fixed on the charging roller, which makes it difficult to collect the toner.

Further, in the contact type charging device of the present invention (claim 6), at least one of the charging roller, the cleaning roller and the auxiliary cleaning roller is directly driven to rotate, and the remaining rollers are driven by gears or the like. By connecting and driving, each roller is prevented from slipping and non-rotating.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A case where the contact type charging device of the present invention is applied to a copying machine will be described in detail as an embodiment with reference to the drawings. First, the operation of the image forming system of the copying machine will be described with reference to FIG. FIG. 1 is an explanatory diagram showing a part of the configuration of the image forming system in the copying machine of the present embodiment, including a photoconductor 101 as an image carrier for forming an electrostatic latent image and a toner image,
Contact type charging roller 10 for charging the photoconductor 101
2 and a power supply 1 for applying a voltage to the charging roller 102
03, a cleaning roller 104 for removing the toner or foreign matter adhering to the surface of the charging roller 102, an auxiliary cleaning roller 105 for contacting the cleaning roller 104 and removing the toner or foreign matter adhering to the cleaning roller 104, and holding Fixed to the member,
The blade edge portion is in contact with the surface of the auxiliary cleaning roller 105 in the counter or trailing direction, and the rubber blade 106 for scraping off the toner or foreign matter adhering to the surface of the auxiliary cleaning roller 105,
A power source 107 for applying a voltage to the auxiliary cleaning roller 105, a control unit 108 for controlling the power source 103, the power source 107, and a solenoid 102f described later, and an electrostatic latent image formed on the photoconductor 101 are visualized. And a transfer unit 11 for transferring the toner image formed on the photoconductor 101 to a recording paper (not shown).
0a, a separation unit 110b for separating the recording paper after the transfer processing from the photoconductor 101, and a cleaning blade housed in a cleaning unit (not shown) for removing the residual toner on the surface of the photoconductor 101 after the separation processing. 111
And a discharging lamp 11 for discharging the residual potential of the photoconductor 101.
2 and.

Reference numeral 109a denotes a developing roller for guiding the toner to the photosensitive member 101 in the developing unit 109. Further, reference numeral 102a denotes an arm that holds the charging roller 102 rotatably around the center of the shaft 102b of the charging roller 102 and moves it toward and away from the photoconductor 101, and 102b fixes the arm 102a. A shaft that is rotatably supported by a side plate (not shown) is shown.
02c indicates a pin press-fitted to the shaft 102b, and 102d
Is held above the pin 102c in the figure, and the charging roller 10
2 indicates a tension spring for bringing the cleaning roller 104 into contact with the cleaning roller 104, 102e is a lower portion of the pin 102c held in the figure, and a tension spring for bringing the charging roller 102 into contact with the photoconductor 101, and 102f indicates a copying operation. In order to bring the charging roller 102 into contact with the photoconductor 101, a solenoid for pulling the pin 102c leftward in the drawing via a tension spring 102e is shown, and 102g is a fixing portion for fixing one end of the tension spring 102d.

One end of the tension spring 102d is fixed to the fixing portion 102g and serves to press the charging roller 102 against the cleaning roller 104 at a constant pressure. The tension spring 102e causes the solenoid 102f to press the charging roller 102 at a constant pressure. And serves to press-contact the photoconductor 101.

The charging roller 102 will be described below. The charging roller 102 has a structure in which a conductive elastic member is wound around the outer periphery of a metal cored bar, and rotates in a direction in which it rotates with the photoconductor 101.

With the above configuration, the operation of the image forming system will be described first. By the charge eliminating lamp 112,
The surface potential of the photoconductor 101 is 0 to −15 when the light is irradiated to
The reference potential is 0V. Next, a charge is applied to the photoconductor 101 by the charging roller 102, and the photoconductor 101 is charged.
Has a surface potential of around -1100V. A voltage is applied to the charging roller 102 by the power supply 103. −
The photoconductor 101 charged to 1100V is irradiated with laser light emitted from a laser diode (not shown).

Here, the laser light will be described.
Digital recording image information sent from an image processing unit (not shown), which is a known technique, is received by a line driver circuit (not shown), and a laser driver circuit (not shown).
Is amplified by. The digital recording image information is a 1-bit (recording / non-recording) binary signal per pixel, and a laser driver circuit activates a laser diode (not shown) to emit light in response to the binary signal. To do. The laser light emitted from the laser diode is imaged and irradiated on the photoconductor 101 as described above.

The surface potential of the portion of the photosensitive member 101 irradiated with light (laser light) (hereinafter referred to as the image portion) is 0 to −.
290V, and the surface potential of the non-image part (background part) not irradiated with light remains -1100V.
01 electrostatic latent image is formed on the surface. The electrostatic latent image is toner-developed by the developing unit 109 to form a toner image on the surface of the photoconductor 101.

In the developing unit 109, since the developing roller 109a is biased at about -800V, the toner in the developing unit 109 adheres to the image portion (surface potential 0 to -290V) and the non-image portion. It does not adhere to (surface potential-1100V).

Along with the formation of the toner image on the surface of the photoconductor 101, a recording paper (not shown) is conveyed from a paper supply unit (not shown). The recording paper is conveyed at the timing when the leading edge of the image in the toner image and the leading edge of the recording paper coincide with each other at the position of the transfer portion 110a. The toner image formed on the surface of the photoconductor 101 is transferred onto the conveyed recording paper by the transfer unit 110a, and the recording paper after the transfer processing is separated into the separation unit 110b.
Is separated from the photoconductor 101. The recording paper separated from the photoconductor 101 is sent to a fixing unit (not shown), and the transferred toner image is fused to the recording paper by heat and pressure and discharged as a copy to the outside of the apparatus.

On the other hand, the residual toner remaining on the photoconductor 101 is scraped off from the photoconductor 101 by a cleaning blade 111 in a cleaning unit (not shown). After removing the residual toner, the photosensitive member 101 moves to the next image forming step in the absence of toner.

Next, the charging roller 1 which is a feature of the present invention.
The operation of the contact / separation mechanism 02 and the cleaning mechanism of the cleaning roller 104 will be described. First, the operation of the cleaning mechanism will be described. The cleaning roller 104 removes the minute toner adhering to the charging roller 102, that is, the toner adhering to the surface of the photoconductor 101 that has passed through the cleaning blade 111 without being scraped off and adhered to the charging roller 102. It serves to remove from the charging roller 102. The cleaning roller 104 has a structure in which a porous sponge member, a bristle brush member, or a felt member is wound around the outer periphery of the core bar. In the present embodiment,
The wound member is electrically conductive.

The member wound around the outer periphery of the cored bar of the cleaning roller 104 is better in conductivity than in insulation, and the reason will be described below. When the auxiliary cleaning roller 105 is charged by applying an electric charge having a polarity opposite to that of the toner or foreign matter adhering to the surface of the charging roller 102, the cleaning roller 1 is charged.
If 04 is conductive, the auxiliary cleaning roller 105
Since the cleaning roller 104 in contact with is charged to the same polarity as the auxiliary cleaning roller 105, toner or foreign matter attached to the charging roller 102 can be electrically adsorbed to the cleaning roller 104.

In this embodiment, the cleaning roller 104 is constructed so as to float. This causes a problem when the cleaning roller 104 is connected to the ground, that is, the charge from the auxiliary cleaning roller 105 flows to the ground through the cleaning roller 104, and when the cleaning roller 104 is set to a predetermined constant potential. The problem that a large capacity power supply is required can be prevented.

The auxiliary cleaning roller 105 of this embodiment is made of a conductive member, and the roller surface has a roughness of 6.3 S or more. As a result, when scraping off the toner or foreign matter attached to the surface of the auxiliary cleaning roller 105 with the scraper or the elastic blade, the attached toner or foreign matter can be completely scraped off.

The auxiliary cleaning roller 105 is supplied with a charge having a polarity opposite to that of the toner or foreign matter adhering to the surface of the charging roller 102 by the power supply 107, and the cleaning roller 104 made of a conductive material also has the same polarity. Be charged. Therefore, the toner or foreign matter on the charging roller 102 can be electrically adsorbed.

The edge of the rubber blade 106 is in contact with the surface of the auxiliary cleaning roller 105 in the counter or trailing direction. As a result, the toner or foreign matter on the surface of the auxiliary cleaning roller 105 is prevented from coming into contact with the rubber blade 106. Completely scraped by. The scraped toner or foreign matter may be collected in a collecting container (not shown), or may be moved to another place by a predetermined collecting coil and collected. Further, in the present embodiment, the toner or foreign matter on the surface of the auxiliary cleaning roller 105 is scraped off by the rubber blade 106, but the invention is not limited to the rubber blade in particular, and the same operation may be performed.

When the charging roller 102 is separated from the photosensitive member 101 and is in contact with the cleaning roller 104, the charging roller 102 and the cleaning roller 104 are in contact with each other.
And the rotational drive is transmitted to at least one roller of the auxiliary cleaning roller 105 by a drive unit (not shown),
The drive is transmitted to the other rollers by a method such as gear connection. Therefore, it is possible to prevent the slip or non-rotation from occurring and prevent the cleaning ability from being deteriorated.

After the copying operation is completed, the solenoid 102f is turned off.
In the FF state, the tension spring 102d causes the arm 102a to rotate counterclockwise in the figure, and the charging roller 10
2 contacts the cleaning roller 104. afterwards,
Rotational force is transmitted to at least one of the charging roller 102, the cleaning roller 104, and the auxiliary cleaning roller 105, and the three rollers rotate. At the same time when the three rollers rotate, the power supply 107 causes the charging roller 1
02 A charge having a polarity opposite to that of the toner or the foreign matter attached to the surface is applied to the auxiliary cleaning roller 105. Since the cleaning roller 104 is electrically conductive and is in a floating state as the charge is applied to the auxiliary cleaning roller 105, the cleaning roller 104 is charged to the same polarity as the auxiliary cleaning roller 105 and adheres to the surface of the charging roller 102. Toner or foreign matter is electrically attracted to the cleaning roller 104, and further to the auxiliary cleaning roller 105.

The toner or foreign matter that is electrically attracted to the auxiliary cleaning roller 105 and adheres to the surface of the auxiliary cleaning roller 105 is completely scraped off by the rubber blade 106, whereby the cleaning roller 104
The surface is always kept clean. Therefore, the charging roller 1 is cleaned by the cleaning roller 104 maintained in this clean state.
02 The cleaning property of the surface is remarkably improved.

[0039]

As described above, the contact type charging device of the present invention (claim 1) is arranged at a position where it comes into contact with the charging roller in a state where the charging roller is separated from the photoconductor by the contacting / separating means. The cleaning roller removes the toner or foreign matter adhering to the surface of the charging roller, and the charge applying means applies an electric charge having a polarity opposite to that of the toner or foreign matter adhering to the charging roller to the auxiliary cleaning formed of a conductive material. Applied to the roller, the auxiliary cleaning roller removes the toner or foreign matter adhering to the surface of the cleaning roller, and the removing means removes the toner or foreign matter adhering to the surface of the auxiliary cleaning roller. Is always kept clean, so it is important to maintain the cleaning performance of the charging roller for a long time. , It is possible to allow a stable charging.

In the contact type charging device of the present invention (claim 2), the removing means is a rubber blade, and the surface roughness of the auxiliary cleaning roller is 6.3 S or more. The surface properties of
Since the ability of the blade to scrape off toner or foreign matter is improved, the cleaning ability of the cleaning roller is improved.

Further, in the contact type charging device of the present invention (claim 3), the cleaning roller is charged to the same polarity by applying a charge to the auxiliary cleaning roller by using a conductive material for the cleaning roller. In order to
Toner or foreign matter on the charging roller can be electrically adsorbed.

Further, in the contact type charging device of the present invention (claim 4), the cleaning roller is set to a constant potential in order to prevent the charge from flowing by electrically floating the cleaning roller. If this is the case, it is possible to avoid using an excessively large capacity power supply.

In the contact type charging device of the present invention (claim 5), the charging roller is separated from the surface of the photosensitive member by the contacting / separating means immediately after the copying operation is completed, and the charging roller is separated from the photosensitive member by the cleaning roller. By cleaning the charging roller when separated from each other, it is possible to prevent the toner from being left on the charging roller for a long time after the copying operation for a long time and sticking the toner onto the charging roller, which makes it difficult to collect the toner. It is possible to maintain and maintain stable charging.

Further, in the contact type charging device of the present invention (claim 6), at least one of the charging roller, the cleaning roller and the auxiliary cleaning roller is directly driven to rotate, and the remaining rollers are driven by gears or the like. By connecting and driving the rollers, slipping and non-rotation of each roller are prevented, so that the cleaning ability can be prevented from lowering.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a contact type charging device and its peripheral portion according to the present embodiment.

FIG. 2 is an explanatory diagram showing a conventional contact type charging device.

FIG. 3 is an explanatory diagram showing a conventional contact type charging device.

[Explanation of symbols]

102 charging roller 102a arm 102b shaft 102c pin 102d tension spring 102e tension spring 102f solenoid 102g fixed part 103 power supply 104 cleaning roller 105 auxiliary cleaning roller 106 rubber blade 107 power supply 108 control part

Claims (6)

[Claims] 1. A contact type charging roller for charging a photosensitive member, a contacting / separating unit for contacting / separating the charging roller from the surface of the photosensitive member, and a state in which the charging roller is separated from the photosensitive member by the contacting / separating unit. A cleaning roller which is disposed at a position in contact with the charging roller and removes toner or foreign matter adhering to the surface of the charging roller; and a cleaning roller which is formed of a conductive material and adheres to the surface of the cleaning roller. The auxiliary cleaning roller for removing the remaining toner or foreign matter, the charge applying means for applying to the auxiliary cleaning roller an electric charge having a polarity opposite to that of the toner or foreign matter attached to the charging roller, and the toner attached to the surface of the auxiliary cleaning roller. Alternatively, the contact type charging device is provided with a removing unit for removing foreign matter. 2. The removing means is a rubber blade,
The surface roughness of the auxiliary cleaning roller is 6.
The contact type charging device according to claim 1, wherein the contact type charging device is 3S or more. 3. The contact type charging device according to claim 1, wherein the cleaning roller is made of a conductive material. 4. The contact type charging device according to claim 3, wherein the cleaning roller is in an electrically floating state. 5. The contacting / separating unit separates the charging roller from the surface of the photoconductor immediately after the copying operation, and the cleaning roller separates the charging roller from the photosensitive member by the contacting / separating unit. The contact type charging device according to claim 1, wherein the charging roller is cleaned. 6. The charging roller, the cleaning roller, and at least one roller of the auxiliary cleaning roller are directly driven to rotate, and the remaining rollers are driven to be connected by a gear or the like. Contact charging device.