JP2001209238A - Electrifying device, image forming device and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent any failure in electrification and deterioration of durability of the electrifying member due to soiling of an electrifying member and generation of a failure in image formation, etc., in an image forming device by securing a good clean state of the electrifying member over a long period of time in a contact type electrifying device and the image forming device or a process cartridge utilizing the electrifying device. SOLUTION: In the electrifying device provided with a movable electrifying member 2 electrifying body to be electrified 1 and with a cleaning member 36 cleaning the electrifying member, a force in a direction orthogonal to direction of movement of the electrifying member 2 is applied to a surface of the electrifying member 2 by the cleaning member 36.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device, an image forming apparatus, and a process cartridge. For more information: a. A contact-type charging device for charging (including static elimination) the surface of the charged body by bringing the charging member into contact with the charged body; b. An image forming apparatus for forming an image by applying an image forming process including a charging step to the surface of the image carrier, and using the charging device as a means for charging the image carrier; c. At least, the present invention relates to an image carrier and a process cartridge that includes the charging device as a means for charging the image carrier and that is attached to and detached from an image forming apparatus main body.

[0002]

2. Description of the Related Art Conventionally, for example, in an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus, an image bearing member such as a photosensitive member or a dielectric body is charged with an electrophotographic process or an electrostatic recording process including a charging step. When the image forming process is applied to form an image, a corona discharge device is used as a charging means of the image carrier, and the image carrier surface is charged by exposing the image carrier surface to a corona generated from the device. Non-contact charging means is widely used. The corona discharge device is effective as a means for uniformly charging the surface of a member to be charged such as an image carrier to a predetermined potential. However, it has problems such as generation of ozone due to corona discharge, which requires a high voltage power supply.

In recent years, contact type charging means (contact charging) has been adopted for such corona discharge devices. Contact charging is a method in which a voltage is applied to a charging member (contact charging member, conductive member) such as a roller type or a blade type, and the charging member is brought into contact with or brought close to the charged member to charge the surface of the charged member. It is.

[0004] In contact charging, compared with a non-contact charging corona discharge device, the applied voltage required to obtain a desired potential on the surface of the charged object can be reduced, and the amount of ozone generated in the charging process can be reduced. However, there is an advantage that there is no need for an ozone removal filter and that the structure of the exhaust system of the apparatus is simplified.

The bias applied to the charging member may be only a DC voltage (DC application method), but it is preferable to apply an oscillating voltage (a voltage whose voltage value changes periodically with time) (AC application method). The present applicant has previously proposed
As described above, in particular, a charging voltage is applied to a charging member by applying an oscillating voltage having a peak-to-peak voltage that is at least twice the charging start voltage of the member to be charged when a DC voltage is applied. This method is effective because uniform charging (static elimination) can be performed. The oscillating voltage is an oscillating voltage component (hereinafter, referred to as an AC component), or the AC component and a DC voltage component (a voltage corresponding to a target charging potential; hereinafter, D
C component) and the waveform of the AC component is a sine wave, a rectangular wave, a triangular wave, or the like. It may be a rectangular wave voltage formed by periodically turning on / off a DC power supply.

FIG. 8 shows a schematic configuration of an example of an image forming apparatus using a contact-type charging device. The image forming apparatus of this embodiment is a transfer type electrophotographic apparatus (copier or printer).

Reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member (hereinafter, abbreviated as a photosensitive member) as a member to be charged. The photoconductor 1 is driven to rotate at a predetermined process speed (peripheral speed) in a counterclockwise direction indicated by an arrow.

Reference numeral 2 denotes a charging member brought into contact with the photosensitive member 1. The charging member 2 of this example is of a roller type (hereinafter, referred to as a charging roller), and has a basic structure including a core 2a and a conductive rubber layer 2b formed concentrically and integrally with the outer periphery of the core 2a in a roller shape. Both ends of the gold 2a are rotatably held by bearing members (not shown), and are pressed against the surface of the photoreceptor 1 with a predetermined pressing force by a pressing means (not shown). The charging roller 2 rotates following the rotation of the photoconductor 1.

Reference numeral 3 denotes a power supply for applying a bias to the charging roller 2. The power supply 3 is electrically connected to the metal core 2 a of the charging roller 2, and a predetermined bias is applied to the charging roller 2 by the power supply 3. Is done. As a result, the peripheral surface of the rotary photoreceptor 1 is uniformly contact-charged to a predetermined polarity and potential by the charging roller 2.

The surface of the photoreceptor 1 charged by the charging roller 2 is then subjected to exposure L of target image information by exposure means (not shown) such as slit exposure means for original images and laser beam scanning exposure means. An electrostatic latent image corresponding to the target image information is formed on the surface of the photoconductor 1. The electrostatic latent image is developed by the developing device 4 as a toner image.

On the other hand, a recording material (transfer material) P is fed one by one from a paper feeding mechanism (not shown), and the recording material P is pressed into contact with a photosensitive member 1 and a transfer roller 5 as a transfer means (transfer nip). The toner image on the photoconductor 1 side is sequentially transferred to the surface of the recording material P by being introduced into the recording material P at a predetermined timing. Reference numeral 6 denotes a transfer bias application power supply for the transfer roller 5.

The recording material P to which the toner image has been transferred is separated from the surface of the photoreceptor 1 and introduced into a fixing device (not shown) to undergo a toner image fixing process.

After the transfer of the toner image onto the recording material P, the surface of the photoconductor 1 is cleaned by a cleaning member 7 of a cleaning device 7.
a (a cleaning blade in this example) removes residual adhered contaminants such as transfer residual toner Ta, etc., and cleans the surface;
The image is subjected to a charge elimination process by a charge elimination unit (not shown), and is repeatedly provided for image formation.

Incidentally, the image forming apparatus as described above has
As the number of times of image formation increases, the charging roller 2 serving as a charging member in contact with the photosensitive member 1 serving as a member to be charged
Is stained with a stain 8 such as toner that has passed through a cleaning blade 7 a as a cleaning member of the cleaning device 7.

As a method for removing the dirt 8, a method has been devised in which the cleaning member 9 is pressed against or separated from the charging roller 2. The cleaning member 9 is a pad member such as a sponge or a fine fiber. The device shown in FIG. 8 is a device in which the cleaning member 9 is constantly pressed against the charging roller 2 with a predetermined intrusion amount, and has a simple configuration. There is an adverse effect such as re-contamination of the charging roller 2 due to the accumulation of dirt on the charging roller 9 and the pressing of the dirt on the charging roller 2. Further, since the cleaning member 9 is in contact with the charging roller 2 even during image formation, a part of the current flowing through the charging roller 2 flows to the cleaning member 9, which is one of the factors that hinder stable charging performance. ing.

Therefore, in order to extend the life of the charging roller 2, it is essential to reduce the chance that the dirt 8 is pressed against the charging roller 2. Since it is necessary to prevent the cleaning member 9 from contacting the charging roller 2 during the formation, as shown in FIG. Pad 9 is connected to solenoid 10
And the link mechanisms 11 and 12 are pressed against the charging roller 2 at a predetermined timing other than during image formation.

Further, as another configuration, when charging for forming an image on the image bearing member 1 by the charging member 2 is not performed, the charging member 2 is separated from the image bearing member 1 and the charging member 2 and the image bearing member are separated from each other. In some cases, the body 1 is prevented from sliding more than necessary and electrical deterioration, dirt and scratches are reduced to achieve long-term use, or charging is controlled by measuring the resistance of the charging member 2.

[0018]

However, in the conventional method of pressing the flat pad 9 like the apparatus shown in FIG. 9, the same position of the cleaning pad 9 comes into contact with the charging roller 2, and the cleaning pad 9 is once pressed. Dirty places have reduced cleaning ability. For this reason, when the durability is advanced, a streak-like dirt is generated at the position of the charging roller 2 and the image is inevitably affected. Further, when extreme dirt is generated in a short time, the dirt on the cleaning pad 9 progresses at a stretch, so that there is no advantage over the system in which the flat pad 9 is constantly applied. As described above, in the conventional method, it is necessary to periodically replace and clean the cleaning pad 9 in order to stably secure the durability of the charging roller 2.

Accordingly, the present invention provides a contact-type charging device or an image forming apparatus or a process cartridge using the charging device, which ensures a good cleaning state of the charging member for a long period of time, thereby causing the charging member to become dirty. It is an object of the present invention to prevent the occurrence of poor charging, reduced durability of the charging member, and the occurrence of poor image formation in an image forming apparatus.

Further, it is possible to prevent the contamination or the like generated at a fixed position in the axial direction of the charging member from growing in the circumferential direction to cause unevenness in deterioration in the axial direction. It is an object of the present invention to form a streak on the top and to prevent local deterioration of the charging member and the image carrier so as not to deteriorate the image.

[0021]

According to the present invention, there is provided a charging device, an image forming apparatus, and a process cartridge having the following structures.

(1) In a charging apparatus having a movable charging member that contacts a member to be charged and charges the member to be charged, and a cleaning member that cleans the charging member, the cleaning member moves in a direction in which the charging member moves. A force in a direction perpendicular to the surface of the charging member.

(2) The charging device according to (1), wherein the cleaning member is driven to reciprocate in a direction orthogonal to a moving direction of the charging member.

(3) The charging device according to (1) or (2), wherein the cleaning member is a pad.

(4) The charging device according to (1), wherein the cleaning member has a spiral shape.

(5) An image forming apparatus comprising: an image bearing member; and a charging means for charging the image bearing member, wherein the charging means is the charging device according to (1).

(6) A process cartridge having at least an image bearing member and a charging means for the image bearing member, which is detachable from the image forming apparatus main body. A process cartridge characterized by being the charging device according to (1).

[Operation] By providing the cleaning member in contact with the charging member with a function of moving dirt in the longitudinal direction of the charging member, the life of the cleaning member can be extended and the cleaning ability can be improved.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> (FIGS. 1 to 4) FIG. 1 is a schematic diagram of a main part of an apparatus of the present embodiment. The apparatus of this embodiment is a transfer type electrophotographic apparatus using a contact-type charging device, and the same reference numerals are given to constituent members and portions common to the above-described apparatuses of FIGS. Omitted.

The photosensitive member 1 as a member to be charged is rotated at a predetermined process speed in a counterclockwise direction indicated by an arrow. A charging roller 2 serving as a charging member has both ends of a cored bar 2a rotatably supported by a bearing member (not shown) and is arranged in parallel with the photoreceptor 1, and is fixed to a surface of the photoreceptor 1 by pressing means (not shown). In this case, the photosensitive member 1 is driven to rotate in accordance with the rotational driving thereof.

Reference numeral 36 denotes a felt pad as a cleaning element that comes into contact with the charging roller 2 and removes contaminants (charge inhibiting substances) on the surface of the charging roller.

FIG. 2 is a front view of a charging roller cleaning mechanism including a felt pad 36 as a cleaning element, with a middle part omitted, FIG. 3 is an enlarged vertical sectional view of a driving pulley part,
FIG. 4 is an enlarged cross-sectional view taken along line (9)-(9) in FIG.

Reference numeral 31 denotes a rail member disposed above the charging roller 2 in the longitudinal direction of the roller in parallel with the roller.
The rail portion 31 is a channel-shaped rail formed by bending a metal plate into a U-shape in cross section. The groove side is directed upward, and both ends are fixedly supported between front and rear side plates of the apparatus main body (not shown).

Reference numeral 32 denotes a stepping motor mounted and held on one side surface of the rail member 31, reference numeral 33 denotes a driving pulley press-fitted into an output shaft 32a of the motor, and reference numerals 32b and 3
2b (FIG. 3) is the bearing of the shaft 32a, 34 is the rail member 31
A driven pulley 34a rotatably provided on the other end of the driven pulley is a rotation center axis of the driven pulley.

Reference numeral 35 denotes a resin slider (cleaning member holder) fitted and engaged with the outside of the rail member 31. The slider 35 is free to slide along the length of the rail member 31.

A felt pad 36 as the cleaning element is fixed to the lower surface of the slider 35 by a double-sided adhesive tape 37 (FIG. 4).

Numeral 38 denotes the lower surface of the rail member 31 and the slider 3
5 is a leaf spring interposed between the inner surface of the bottom of the slider 5 and the inner surface of the slider 35 which is thermally caulked. This leaf spring 3
8 is pressed between the lower surface of the rail member 31 and the inner surface of the bottom of the slider 35 when the slider 35 is fitted and engaged with the outside of the rail member 31, and presses a felt pad 36 as a cleaning element against the upper surface of the charging roller 2. Acts to be.

39 is a metal tension wire,
One end thereof is engaged with the slider 35, is wound around the driving pulley 32 a plurality of times (FIG. 3), is wound around the driven pulley 33, and the other end is engaged with the slider 35.

With the above configuration, the stepping motor 3
2 is driven forward and backward, the rotational force is transmitted to the drive pulley 32 and the wire 39, and the slider 35, that is, the felt pad 36 as a cleaning element moves along the rail member 31 by the pulling by the wire 39. It is moved and moved back. That is, the felt pad 36 is reciprocally slid and moved (thrust movement) along the roller length while being in contact with the charging roller 2. The reciprocating range of the felt pad 36 is between the point A on one end of the charging roller 2 and the point B on the other end.

With such a configuration, the stepping motor 3
2, the contact point C of the felt pad 36 with the charging roller 2 rubs the surface of the charging roller 2 while reciprocating between points A and B at both ends of the charging roller 2. The surface of the charging roller 2 is cleaned by the thrust motion. In this configuration, since the felt pad 36 as a cleaning element moves in the longitudinal direction of the charging roller 2, a part of the circumference of the charging roller surface is not significantly stained.

<Second Embodiment> (FIGS. 5 and 6) FIG. 5 is a front view of the charging roller cleaning mechanism according to the present embodiment, in which a part of the spiral roller as a cleaning member is omitted. It is a top view.

Reference numeral 41 denotes a spiral roller as a cleaning member, and the cleaning element 4 extends along the length of the shaft 42.
As No. 3, a short felt sheet is spirally wound around a gap and attached.

The spiral roller 41 is connected to a shaft 42
Are rotatably held by bearing members (not shown), arranged above the charging roller 2 in parallel with the roller in the longitudinal direction of the roller, and pressed against the charging roller 2 by pressing means (not shown). It is. The spiral roller 41 is rotated by the motor 44 with a peripheral speed difference from the charging roller 2.

The longitudinal force F _S as shown in FIG. 6 the charging roller 2 viewed from Te by the edge 43a of the felt sheet 43 as a cleaning element foulant on the surface of the charging roller 2 is wound in a spiral shape by this arrangement, the circumferential And the directional force F _R.

The dirt is sequentially moved in the longitudinal direction of the charging roller 2 by the longitudinal force F _S , passes through the edge 43 a little by little while being dispersed, and contacts and adheres to the surface of the felt sheet 43 as a cleaning element. Thus, the surface of the charging roller 2 is cleaned. With this configuration,
The cleaning member 41 does not depend on a part of the dirt, so that it is possible to prevent the occurrence of a partially defective cleaning part. In addition, since the dirt is removed using the edge 43a, the power of removing dirt becomes stronger than before, and the cleaning ability is improved.

In this embodiment, a felt is used as a cleaning element for the cleaning member. However, the present invention is not limited to the felt, and an effect can be obtained if the member is elastic enough to form a nip between the charging roller and the charging roller.

As described above, as in the first and second embodiments, the cleaning members 36 and 41 that come into contact with the charging roller 2 are used.
By providing the ability to move dirt in the longitudinal direction of the charging roller, effects such as prolonging the life of the cleaning member and improving the cleaning ability were obtained.

Third Embodiment (FIG. 7) This embodiment is a schematic configuration diagram of an example of an image forming apparatus using the charging device of the first or second embodiment.

The image forming apparatus of this embodiment is a copying machine using a fixed original platen / movable optical system and a transfer type electrophotographic process.

Reference numeral 71 denotes an exterior casing of the apparatus, and reference numeral 72 denotes a fixed document table glass disposed on an upper panel of the exterior casing.
The original O is placed on the original platen glass 72 with the image surface to be copied facing downward according to a predetermined placement standard, and the original O is pressed down and set by covering it with an original pressing plate 73.

When the copy start button of the operation unit (not shown) is pressed, the illumination lamp 74 of the moving optical system is pressed.
When the first mirror 75 is V along the lower surface of the platen glass 72
And the second and third mirrors 76 and 77
By moving forward at a speed of / 2, the downward image surface of the set document O on the platen glass 72 is optically scanned, and the document image is rotated via the imaging lens 78 and the fixed fourth to sixth mirrors 79 to 81. The surface of the photoconductor 1 is subjected to slit image formation exposure L.

The rotating photoreceptor 1 is uniformly primary-charged to a predetermined polarity and potential by a charging roller 2 by a contact charging method, and the charged surface is exposed to the above-mentioned exposure L to correspond to the image of the original O. A formed electrostatic latent image is formed. The latent image is then developed by the developing device 4 as a toner image.

On the other hand, the sheet feeding roller 85 is fed from the first or second sheet feeding cassette 82 or 83 or the manual sheet feeding table 84.
Or, at 86 or 87, the transfer sheet P is fed out one by one, and is conveyed to the registration roller pair 78 through the sheet path.
The toner image on the photoconductor 1 side is conveyed to the transfer sheet P by being conveyed to the transfer nip portion which is a press contact portion between the photoconductor 1 and the transfer roller 5 at a predetermined timing by the registration roller pair 78. It is transcribed sequentially.

The transfer sheet P to which the toner image has been transferred at the transfer nip portion is separated from the surface of the photoreceptor 1,
Then, the toner image is subjected to the fixing process of the toner image, and is sent out to a paper tray 92 outside the apparatus by a discharge roller pair 91.

After the transfer of the toner image onto the transfer sheet P, the surface of the rotary photoreceptor 1 is cleaned by the cleaning device 7 to remove contaminants such as untransferred toner and the like. After being subjected to a charge elimination process by the charge elimination means, the image is repeatedly provided for image formation.

The cleaning mechanism of the charging roller 2, its operation sequence, and the like are the same as those in the first or second embodiment, so that the description will not be repeated.

In the image forming process equipment, at least four photoconductors 1 and a charging roller 2, generally four photoconductors 1, a charging roller 2, a developing device 4, and a cleaning device 7 are collectively mounted on the apparatus main body side. On the other hand, it can be configured as a detachable and replaceable process cartridge.

The charging member may be of a belt type, a blade type, a rod type, a pad type, etc. other than the charging roller 2. It may be a friction charging member.

[0059]

As described above, according to the present invention, the cleaning member in contact with the charging member is provided with the function of moving dirt in the longitudinal direction of the charging member, so that a portion of the surface of the charging member is markedly remarkable. It is possible to extend the life of the cleaning member without contamination and to improve the cleaning ability. Even if accidental extreme contamination occurs on the charging member, it is possible to secure and maintain a good cleaning state of the charging member over a long period of time during the life of the charging member.

In the image forming apparatus, it is possible to prevent the occurrence of defective image formation and the like, to prevent local deterioration of the charging member and the image carrier, and to prevent the image from being deteriorated.

[Brief description of the drawings]

FIG. 1 is a schematic view of a configuration of a main part of an apparatus according to a first embodiment.

FIG. 2 is a front view of a charging roller cleaning mechanism with a middle part omitted.

FIG. 3 is an enlarged vertical sectional view of a driving pulley portion of the mechanism.

FIG. 4 is an enlarged cross-sectional view taken along line (9)-(9) in FIG. 2;

FIG. 5 is a front view of the charging roller cleaning mechanism of the second embodiment in which an intermediate portion is omitted.

FIG. 6 is an enlarged plan view of a part of a spiral roller as a cleaning member of the mechanism.

FIG. 7 is a schematic structural diagram of an image forming apparatus as a third embodiment apparatus.

FIG. 8 is a schematic configuration diagram of an example of an image forming apparatus using a contact-type charging device.

FIG. 9 is a diagram of a mechanism for moving a cleaning member toward and away from a charging roller.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor (charged body) 2 Charging roller (charging member) 36 Felt pad as cleaning element 31-36, 39 Felt pad reciprocating mechanism 41 Spiral cleaning roller

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Haruo Naruse 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Toshinori Iwasaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inside the corporation

Claims (6)

[Claims] 1. A charging device, comprising: a movable charging member that contacts a member to be charged and charges the member to be charged; and a cleaning member that cleans the charging member. A charging device, wherein a force in a direction perpendicular to the charging member is applied to a surface of the charging member. 2. The charging device according to claim 1, wherein the cleaning member is driven to reciprocate in a direction orthogonal to a moving direction of the charging member. 3. The charging device according to claim 1, wherein the cleaning member is a pad. 4. The charging device according to claim 1, wherein the cleaning member has a spiral shape. 5. The image processing apparatus according to claim 1, further comprising an image carrier, and a charging unit for charging the image carrier, wherein the charging unit is the charging device according to any one of claims 1 to 4. Image forming apparatus. 6. A process cartridge having at least an image carrier and a charging unit for the image carrier, the cartridge being a process cartridge detachably attached to an image forming apparatus main body, wherein the charging unit is provided. 5. A process cartridge, which is the charging device according to any one of items 1 to 4.