JP2000181199A - Electrifier having cleaner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability and the long-use stability of an electrifier of a power feed system in which an electrifying current is caused to flow in the direction of the circumference of an electrifying roller. SOLUTION: In an image forming device of an impression development system, a supply current to an electrifying roller 1 composing an electrifier for a photoreceptor drum 3 is supplied from a constant voltage source 4 by a power feed roller 2 rotating while keeping the linear or face contact with the electrifying roller 1. Because the supply current flows in the direction of the circumference of an electrifying roller, a high resistance value is obtained and electrification stability is ensured. However, sticking of transfer residual toner, paper powder, and so on may impair the stability, etc., of the electrifier. By providing a scraping (cleaning) member 5, transfer residual toner and so on are scraped to clean the surface of the electrifying roller 1 and hence to improve the durability and stability of the electrifier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device having a cleaning device, and more particularly, to a charging device having a cleaning device for an image forming apparatus used in a copying machine, a facsimile machine or the like.

[0002]

2. Description of the Related Art A so-called impression development comprising a paper feeding unit for supplying printing paper, a developing unit for performing respective steps of charging, exposure, development, transfer, fixing and cleaning, and a paper discharging unit for discharging printed paper. Image forming apparatuses of the type are well known.

FIG. 6 is a schematic cross-sectional view of a conventional image forming apparatus having the above configuration. In FIG. 6, reference numeral 10 denotes a paper feed unit for supplying printing paper S for image formation, and reference numeral 20 denotes each of the above steps. Is a developing unit where the printing is performed, and 30 is a paper discharging unit for discharging the printed paper.

A paper feed unit 10 has a rear end pivotally supported so as to be swingable, a paper mounting plate 11 for mounting a print paper S, a paper feed roller 12 for supplying the print paper S to a developing unit, A compression spring 13 for pressing the mounting plate 11 in the direction of the paper feeding roller 12; when the paper feeding roller 12 is driven at a paper feeding timing by a driving device (not shown),
The first printing paper S is supplied to the developing unit 20.

The developing unit 20 includes a photosensitive drum 21 on which a photoconductive layer whose electrical characteristics change by light irradiation is formed, a charging roller 22 for charging the surface of the photosensitive drum 21 with static electricity, and a charging roller 22. A charging device including a power supply roller 23 for supplying power, an exposure unit 24 for irradiating a print pattern onto the photosensitive drum 21 to form an electrostatic latent image on the photosensitive drum 21, and a supply roller 25 for supplying toner. A developing roller 26 for carrying out development by pressing the photosensitive drum 21 while carrying the toner supplied from the supply roller 25. The printing paper is brought into close contact with the printing paper by bringing the printing paper into close contact with the photosensitive drum 21 to which the toner is adhered by the developing roller 26. A transfer roller 27 for transferring to a sheet, and a fixing roller for applying heat and pressure to the print sheet to fix the toner on the print sheet 8, and has a cleaning unit 29 for scraping off toner remaining on the photosensitive drum 21 to not completely transferred to the printing paper.

These are operated by a known operation method of a so-called impression development system to print image information of a document (not shown) on a print sheet S and discharge the image information to a discharge unit 30.

Conventionally, a corona discharge type charging device has been used as a charging device for charging the developing type photosensitive drum with static electricity. However, the discharge wire is easily cut and it takes time to replace the discharge wire. Recently, a charging roller having a semiconductive layer on the surface of a conductive roller made of metal or the like and a semiconductive layer have been recently developed because spark discharge occurs between cases and there is a limit in reducing the shape of the corotron. A contact-type charging device that uses a power supply roller for supplying power to the power supply is used.

FIG. 7 is a diagram schematically showing a cross section of a conventional contact charging type charging device. FIG.
(B) shows a longitudinal section, in which 40 is a charging roller, 41 is a charging roller base formed of aluminum or the like, 42 is a shaft of the charging roller 40, and 43 is a doping and coating on the charging roller base 41. Alternatively, the semiconductive layer 44 provided by covering the heat shrinkable tube or the like is a gap holding member formed of polyacetal or the like. The gap holding member 44 has, for example, a disk shape, and has a shaft hole (not shown) that fits with the shaft portion 42 at the center.
A predetermined discharge gap length d can be obtained between the photosensitive drum 21 and the semiconductive layer 43 only by attaching the charging roller base 41 to both ends of the shaft portion 42 and abutting the photosensitive drum 21. The photosensitive drum 21 is charged by supplying power to the charging roller base 41 from the constant voltage source 45 via the shaft 42.

According to such a charging method, the supply current is supplied from the shaft 42 of the charging roller 40 to the base 41 of the charging roller.
Therefore, since it flows in the thickness direction of the semiconductive layer 43 after passing through, a sufficient resistance value cannot be obtained, and stable charging cannot be performed.

Therefore, the inventor provided a charging current supply member for supplying a charging current by contacting the charging member whose discharge surface rotates with respect to the member to be charged by rotating the charging member in the longitudinal direction of the rotation axis of the charging member. (Japanese Patent Application No. 10-357969) has developed a charging device that obtains a sufficient resistance value by supplying power from the surface of the device and enables stable charging.

[0011]

As a result of further research, the inventor has found that a charging device that supplies power from the surface of the charging member enables stable charging, but the charging device does not adhere to the charging device. The transfer residual toner and paper dust that occur cause more uneven charging, and the durability of the charging device and the stability during long-term use (hereinafter referred to as durability stability).
For the first time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a charging member that rotates facing a member to be charged and a rotating member that holds a linear or planar contact portion with the charging member. Accordingly, the present invention provides a charging device having a cleaning device provided with a cleaning device in a charging device having a charging current supply member for supplying a charging current to the charging member.

[0013]

According to a first aspect of the present invention, there is provided a charging member having a semiconductive layer provided on a surface of a cylindrical insulating base, and rotating in opposition to an object to be charged. A charging current supply member that supplies a charging current to the charging member by rotating while holding a linear or planar contact portion, and a cleaning device provided to face the surface of the charging member or the power supply current supply member Wherein the charging device has improved durability stability.

According to a second aspect of the present invention, in the first aspect of the present invention, the cleaning device is provided to face a surface of the charging member that contacts the power supply current supply member, and cleans the surface. The cleaning is performed easily and efficiently.

According to a third aspect of the present invention, in the first aspect of the invention, the cleaning device is provided to face a surface of the power supply current supply member that contacts the charging device, and the cleaning member cleans the surface. The cleaning is performed without damaging the charging member such as flaws.

According to a fourth aspect of the present invention, there is provided a charging member comprising a semiconductive layer provided on the surface of a cylindrical insulating base, the charging member rotating to face a member to be charged, and a charging current supply member having a conductive brush. A cleaning device is provided in a charging device having a charging current supply member that supplies a charging current to the charging member by holding and rotating a contact portion of the charging member and the conductive brush, The cleaning is performed while power is supplied to the charging device to improve the durability stability of the charging device.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the cleaning device comprises a rotating member to which a bipolar voltage is applied from a constant voltage source and which rotates in contact with the brush; It is a cleaning member that cleans the rotating surface, and cleans the transfer residual toner, which is opposite in polarity to the predetermined polarity for developing the electrostatic latent image formed on the charged body. It is something to do.

[0018]

FIG. 4 is a view schematically showing a cross section of a charging device to which the present invention is applied. In FIG.
Are polycarbonate (PC), polyamide (PA),
Base 1 made of insulating resin such as polyimide (PI)
The semiconductor device has a semiconductive layer 1b provided on a by doping, coating or coating of a heat-shrinkable tube. 1c
Is a shaft portion of the charging roller 1, and 1d is a gap holding member formed of polyacetal or the like. The gap holding member 1d has, for example, a disk shape and is provided at the center with a shaft hole (not shown) that fits into the shaft portion 1c. Only by contact, a predetermined discharge gap length d can be obtained between the photosensitive drum 3 and the semiconductor layer 1b.

Reference numeral 2 denotes a power supply roller formed of a conductive and elastic material such as conductive urethane, conductive silicon, or conductive urethane foam, and 2a denotes a shaft portion of the power supply roller 2; Power is supplied from the constant voltage source 4 via the shaft 2a.

The charging roller 1 and the power feeding roller 2 hold linear or planar (nip width n) contact portions in the direction of the rotation axis of the rollers by driving the shaft portions 1c and 2a by a driving device (not shown). And rotate. Therefore, according to the above configuration, the power supply current is controlled by the charging roller 1 and the power supply roller 2.
From the contact portion to the discharge surface where the charging roller 1 and the photosensitive drum 3 face each other, the surface of the semiconductive layer 1b of the charging roller 1 flows in a circumferential direction, so that the photosensitive drum 3 can be stably charged. Has sufficient electric resistance (10 ⁹ ) to cause a stable discharge in the gap between the charging roller 1 and the photosensitive drum 3 (the position where the discharge gap length d is shown in the figure).
Ohms).

FIG. 5 is a diagram schematically showing a cross section of another charging device to which the present invention is applied. In the drawing, reference numeral 7 denotes a power supply roller including a brush 7a and a roller member 7b. The power supply roller 7 has a conductive member affixed over the entire surface of the roller member 7b as a main body, or the roller member 7b itself is formed of a conductive material, and a conductive brush 7a is implanted thereon. You. The brush 7a is energized from the constant voltage source 4. The same components as those in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted.

When the charging roller 1 and the feeding roller 2 are rotationally driven by a driving device (not shown), a charging current is supplied from the constant voltage source 4 to the charging roller 1 via the brush 7a. By implanting the brush 7a with regularity in the axial direction and the circumferential direction, the brush 7a can be rotated while substantially holding the linear or planar contact portion described in FIG. After that, a charging current is supplied to the charging roller 1. At this time, the brush 7a performs cleaning of the charging roller 1 together with power supply.

FIG. 1 is a diagram schematically showing a cross section of a charging device having a cleaning device for explaining an embodiment of the present invention. In the drawing, reference numeral 5 denotes a scraping member of a charging roller. The same components as those in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted. The charging roller 1 and the power supply roller 2 rotate while holding a linear or planar (nip width n) contact portion in the rotation axis direction of the roller by driving the shaft portions 1c and 2a by a driving device (not shown). I do. When power is supplied from the constant voltage source 4 to the power supply roller 2, the power supply current flows from the contact portion between the power supply roller 2 and the charging roller 1 in the circumferential direction on the surface of the semiconductive layer 1 b of the charging roller 1, and Is charged. At this time, the scraping member 5 comes into sliding contact with the agent with respect to the rotation of the charging roller 1 to scrape off the untransferred toner and paper dust attached to the surface of the charging roller 1. Since the surface of the charging roller is directly cleaned, the apparatus can be efficiently cleaned.

FIG. 2 is a diagram schematically showing a cross section of a charging device having a cleaning device for explaining another embodiment of the present invention. In the drawing, reference numeral 6 denotes a scraping member of a power supply roller. The same components as those in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted. When the charging roller 1 and the power supply roller 2 rotate in the same manner as in the charging device of FIG. 4 and power is supplied from the constant voltage source 4 to the power supply roller 2, the power supply current flows between the charging roller 1 and the power supply roller 2. The surface of the semiconductive layer 1b of the charging roller 1 flows circumferentially from the contact portion to the discharge surface (charging position) facing the photosensitive drum 3, and the photosensitive drum 3 is charged. At this time, the scraping member 6 comes into sliding contact with the power supply roller 6 against the power supply roller 6 to scrape off transfer residual toner and the like attached to the surface of the power supply roller 2. The transfer residual toner and the like adhered to the charging roller 1 are once adhered to the power supply roller 2 and then scraped off on the power supply roller 2 side, so that the scraping member 6 does not directly contact the charging roller 1 and the charging roller 1 is damaged. Since the cleaning of the charging roller 1 is performed without damaging the charging roller 1, the uniformity of charging, the durability of the charging device, and the stability during long-term use (durability stability) can be improved.

FIG. 3 is a diagram schematically showing a cross section of a charging device having a cleaning device for explaining still another embodiment of the present invention. In the drawing, reference numeral 8 denotes a conductive cleaning roller of the power supply roller 7. , 9 is a scraping member and 4 'is a constant voltage source. The same components as those in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted. Charging roller 1 and feeding roller 7
Operates in the same manner as the charging device of FIG. Accordingly, the power supply current to the charging roller 1 flows from the constant voltage source 4 to the surface of the semiconductive layer 1b of the charging roller 1 from the contact portion between the charging roller 1 and the brush 7a of the power supply roller 2 in the circumferential direction. The drum 3 is charged. At this time, the surface of the charging roller 1 is cleaned by the contact between the charging roller 1 and the brush 7a.

Further, the brush 7a includes a cleaning roller 8
The voltage is applied to the cleaning roller 8 from the constant voltage source 4 ′, and the scraping member 9 is in sliding contact with the cleaning roller 8 against the cleaning roller 8. Therefore, by applying a bipolar potential periodically from the constant voltage source 4 ', it is possible to scrape off and remove the transfer residual toner having the opposite charge.

The charging roller 1 and the power supply roller 6 are driven at different rotational speeds, and the two rollers have different peripheral speeds, so that the charging roller 1 can be effectively cleaned by the brush 7a.

[0028]

According to the first aspect of the present invention, a semiconductive layer is provided on the surface of a cylindrical insulating base, and the charging member rotates in opposition to the member to be charged. Or a charging current supply member that supplies a charging current to the charging member by rotating while holding a planar contact portion, and a cleaning device provided to face the surface of the charging member or the power supply current supply member. As a result, the durability of the charging device and the stability during long-term use can be improved.

According to the second aspect of the present invention, in addition to the effect of the first aspect, the cleaning device is provided so as to face a surface of the charging member which comes into contact with the power supply current supply member. Since the cleaning member cleans the charging member, the surface of the charging member is directly cleaned, so that the cleaning can be easily and efficiently performed.

According to the third aspect of the present invention, in addition to the effect of the first aspect, the cleaning device is provided so as to face a surface of the power supply current supply member that contacts the charging device, and the cleaning device is provided with the cleaning device. The cleaning member can clean the charging member without damaging the charging member.

According to the fourth aspect of the present invention, a semiconductive layer is provided on the surface of the cylindrical insulating base, and a charging member which rotates facing the member to be charged and a charging current supply having a conductive brush are provided. Since a charging device having a charging current supply member that supplies a charging current to the charging member by holding and rotating a contact portion between the charging member and the conductive brush is provided with a cleaning device, Cleaning can be performed while power is supplied to the device to improve the durability stability of the charging device.

According to the fifth aspect of the present invention, in addition to the effect of the fourth aspect of the present invention, in the cleaning device, a rotating member to which a bipolar voltage is applied from a constant voltage source and which rotates in contact with the brush. And a cleaning member for cleaning the rotating surface of the rotating member, so that the transfer residual toner having the opposite polarity to the predetermined polarity for developing the electrostatic latent image formed on the member to be charged is also excellent. Can be cleaned.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a charging device for explaining an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a charging device for explaining another embodiment of the present invention.

FIG. 3 is a cross-sectional view of a charging device for explaining still another embodiment of the present invention.

FIG. 4 is a diagram schematically showing a cross section of a charging device to which the present invention is applied.

FIG. 5 is a diagram schematically showing a cross section of another charging device to which the present invention is applied.

FIG. 6 is a schematic cross-sectional configuration diagram of a conventional image forming apparatus.

FIG. 7 is a diagram schematically showing a cross section of a conventional charging device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Charging roller, 1a ... Insulating base, 1b ... Semiconductive layer,
1c: Shaft, 1d: Gap holding member, 2: Power supply roller, 2
a: shaft part, 3: photosensitive drum, 4, 4 '... constant voltage source, 5,
6: scraping member, 7: feeding roller, 7a: brush, 7
b: roller member, 8: cleaning roller, 9: scraping member, 10: paper feed unit, 11: paper loading plate, 12
... Supply roller, 13 ... Compression spring, 20 ... Development unit,
DESCRIPTION OF SYMBOLS 21 ... Photosensitive drum, 22 ... Charging roller, 23 ... Power supply roller, 24 ... Exposure part, 25 ... Supply roller, 26 ... Developing roller, 27 ... Transfer roller, 28 ... Fixing roller, 29 ... Cleaning part, 30 ... Paper discharge unit , 40 ... Charging device, 4
DESCRIPTION OF SYMBOLS 1 ... Charge roller base, 42 ... Shaft part, 43 ... Semiconductive layer, 4
4 ... gap holding member, 45 ... constant voltage source, d ... discharge gap length,
n: Nip width, S: Printing paper

Claims (5)

[Claims] 1. A charging member having a semiconductive layer provided on a surface of a cylindrical insulating base and rotating to face a member to be charged,
A charging current supply member for supplying a charging current to the charging member by holding and rotating the linear or planar contact portion with the charging member, and a charging current supply member provided to face the surface of the charging member or the power supply current supply member. And a cleaning device provided with the cleaning device. 2. The cleaning device according to claim 1, wherein the cleaning device includes a cleaning member that is provided to face a surface of the charging member that contacts the power supply current supply member and cleans the surface. Charging device having the cleaning device of (1). 3. The cleaning device according to claim 1, wherein the cleaning device includes a cleaning member that is provided to face a surface of the power supply current supply member that contacts the charging device and cleans the surface. Charging device having the cleaning device of (1). 4. A charging member having a semiconductive layer provided on a surface of a cylindrical insulating base and rotating in opposition to a member to be charged,
A charging current supply member having a conductive brush, and a charging current supply member for supplying a charging current to the charging member by rotating while holding a contact portion of the charging member and the conductive brush; A charging device having a cleaning device, comprising the cleaning device. 5. The cleaning device according to claim 1, wherein the cleaning device is a rotating member to which a voltage of both polarities is applied from a constant voltage source and rotates in contact with the brush, and a cleaning member for cleaning a rotating surface of the rotating member. A charging device comprising the cleaning device according to claim 4.