JP2008122778A - Charging device and image forming apparatus having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify configuration by reducing the number of components while maintaining satisfactory charging of an image carrier by a charging member for a long time. <P>SOLUTION: The blade support member 7b of a cleaning blade 7a is attached so as to be rotatable around a rotation shaft 9. The brush support member 3 of a charging brush 3d is attached to the blade support member 7b. The blade support member 7b is constantly pressed counterclockwise by a spring 11, thereby bringing the cleaning blade 7a and charging brush 3d into firm contact with a photoreceptor 2. During an image forming operation, the charging brush 3d is vibrated by the stick slip motion of the cleaning blade 7a. Thus, toner and foreign matter sticking to a first charging brush 3d is shaken off. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technical field of an image forming apparatus including a charging device for charging an image carrier and an electrophotographic apparatus.

  In a conventional image forming apparatus including an electrophotographic apparatus such as an electrostatic copying machine, a printer, or a facsimile, the surface of the photosensitive member is uniformly charged by the contact charging device, and then electrostatically applied to the surface of the photosensitive member by the exposure device. A latent image is formed. The electrostatic latent image is developed into a toner image by a developing device, and is transferred to a transfer material such as paper via an intermediate transfer member or directly. Finally, an image is formed by fixing the toner image on the transfer material by a fixing device.

  By the way, in a conventional image forming apparatus, there is known an image forming apparatus provided with a charging device in which two charging members are brought into contact with the photoconductor in order to uniformly and satisfactorily charge the surface of the rotating photoconductor. (For example, see Patent Document 1). In the charging device of this image forming apparatus, the charging unevenness when the surface of the photosensitive member is charged by the contact charging member on the upstream side in the rotation direction of the photosensitive member is removed by the contact charging member on the downstream side in the rotation direction of the photosensitive member. Are uniformly charged.

However, due to long-term use of the image forming apparatus or the like, toner or foreign matter may adhere to the contact charging member, the contact charging member may become dirty, and charging unevenness may occur. Therefore, in the charging device described in Patent Document 1, a flocked sheet is affixed to a PET sheet, and the flocked sheet is in contact with a charging roller that is a contact charging member on the downstream side in the rotation direction of the photoreceptor. The flocking sheet functions as a dedicated cleaning member for the charging roller. Thereby, the cleaning performance of the charging roller can be maintained for a long time, and the life of the contact charger is extended. Although not exemplified in addition to Patent Document 1, various methods for cleaning the contact charging member with a dedicated cleaning member have been proposed.
JP-A-2005-215321.

  However, in the charging device having two conventional contact charging members such as the charging device described in the above-mentioned Patent Document 1, a dedicated cleaning member is simply brought into contact with the contact charging member. For this reason, the cleaning effect of the contact charging member by the cleaning member is not always sufficiently obtained. Further, since a dedicated cleaning member is required, the number of parts is not only large, but the configuration is complicated accordingly.

  The present invention has been made in view of such circumstances, and the object thereof is to reduce the number of parts and simplify the configuration while maintaining good charging of the image carrier by the charging member for a long period of time. A charging device and an image forming apparatus including the charging device are provided.

In order to solve the above problems, according to the present invention, the first charging member is vibrated by the stick-slip motion of the cleaning blade of the image carrier during the image forming operation. Due to the vibration of the first charging member, the toner and foreign matter adhering to the first charging member are shaken off, so that the contamination of the first charging member due to the toner and foreign matter can be removed and the charging property can be improved. Therefore, the image carrier can be charged with the first charging member satisfactorily over a long period of time, and a high-quality image can be obtained.
In addition, since a dedicated cleaning member for removing dirt on the first charging member is not required, the number of parts can be reduced and the configuration of the charging device can be simplified.

  Further, by using a charging brush for the first contact charging member, the brush bristles of the charging brush can be more effectively vibrated during the image forming operation. As a result, it is possible to more reliably remove dirt due to toner and foreign matters adhering to the charging brush.

  Further, the contact point of the cleaning blade with the image carrier is set on the upstream side in the rotation direction of the image carrier with respect to the straight line connecting the rotation center of the image carrier and the rotation center of the cleaning blade. Further, the contact point of the first contact charging member with the image carrier is set on the downstream side in the rotation direction of the image carrier from this straight line. Thereby, the amount of biting of the first contact charging member into the image carrier can be reduced according to the durable deflection of the cleaning blade. Therefore, film scraping of the image carrier due to the pressure contact of the first contact charging member can be suppressed, and the life of the apparatus can be extended.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram schematically and partially showing an example of an embodiment of an image forming apparatus according to the present invention.

  As shown in FIG. 1, an image forming apparatus 1 of this example includes a photosensitive member 2 that is an image carrier on which an electrostatic latent image and a toner image are formed. The photosensitive member 2 is, for example, a cylindrical photosensitive member. It consists of a drum and is rotated in the clockwise rotation direction α in FIG. The charging device 3 that sequentially contacts and charges the photoconductor 2 around the photoconductor 2 from the upstream side of the rotation direction α of the photoconductor 2, the optical writing device 4 that writes an electrostatic latent image on the photoconductor 2, and the static of the photoconductor 2 A developing device 5 that performs non-contact jumping development of the electrostatic latent image with toner, a transfer device 6 that transfers the toner image of the photoreceptor 2, and a cleaning device 7 that cleans the photoreceptor 2 are provided.

  The charging device 3 includes a charging roller 3a (second charging member) that charges the photosensitive member 2 and a charging brush 3d (second charging member) that similarly charges the photosensitive member 2 upstream of the charging roller 3a in the rotation direction α. 1 charging member). The charging roller 3a is in contact with the outer peripheral surface of the photoconductor 2 and is rotated in the direction β opposite to the rotation direction α of the photoconductor 2 (counterclockwise in FIG. 1).

  As the charging roller 3a, a known charging roller that has been conventionally used can be used. That is, the charging roller 3a can be manufactured by a manufacturing method described in, for example, JP-A-10-48916. That is, the charging roller 3a is configured by providing, for example, a cylindrical conductive elastomer layer 3c made of, for example, conductive rubber or the like having a surface inclined resistance layer on a metal shaft 3b made of stainless steel. ing.

  The charging brush 3d has a large number of bristles and is supported by a brush support member 3e. The tips of a large number of brush hairs are in contact with the outer peripheral surface of the photoreceptor 2. As the charging brush 3d, a known charging brush that has been conventionally used can be used. An example of the charging brush 3d is shown in Table 1.

As shown in Table 1, the brush hair of the brush 1 as an example has a material of 6 nylon, a fineness of 220T / 96F, a density of 240 kf / inch ² , a yarn resistance of 7.1 LogΩ, and a pile length of 5 mm. The overall shape of the brush 1 is 300 mm in length (along the axial direction of the photoreceptor 2), 5 mm in width, and 5 mm in height. As another example, the brush bristles of the brush 2 are made of nylon 6 material, a fineness of 330 T / 48 F, a density of 80 kf / inch ² , a yarn resistance of 9.3 LogΩ, and a pile length of 5 mm. The overall shape of the brush 1 is 300 mm in length (along the axial direction of the photoreceptor 2), 5 mm in width, and 5 mm in height.
The photoreceptor 2 is first charged by the charging brush 3d and then charged by the charging roller 3a.

  The optical writing device 4 writes an electrostatic latent image on the photosensitive member 2 with, for example, a laser beam. The developing device 5 includes a developing roller 5a, a toner supply roller 5b, and a toner layer thickness regulating member 5c. At both ends of the developing roller 5a, developing rollers 5d (only one developing roller 5a is shown in FIG. 1) are provided. These developing rollers 5d constitute a developing roller / image carrier axis distance regulating member. In other words, the distance between the axial center of the developing roller 5 a and the axial center of the photosensitive member 2 is regulated by the development rollers 5 d coming into contact with the outer peripheral surface of the photosensitive member 2. Thus, a predetermined development gap is set between the outer peripheral surface of the developing roller 5a and the outer peripheral surface of the photoreceptor 2.

  Then, toner (not shown) as a developer is supplied onto the developing roller 5a by the toner supply roller 5b, and the toner on the developing roller 5a is regulated in thickness by the toner layer thickness regulating member 5c, so that the photoconductor. 2, the electrostatic latent image on the photoreceptor 2 is jumped and developed with the conveyed toner, and a toner image is formed on the photoreceptor 2.

  The transfer device 6 has a transfer roller 6a, and a toner image is transferred onto the photosensitive member 2 by the transfer roller 6a onto a transfer medium 8 such as transfer paper or an intermediate transfer medium. When the toner image is transferred to the transfer paper that is the transfer medium 8, the toner image on the transfer paper is fixed by a fixing device (not shown), an image is formed on the transfer paper, and the toner image is transferred to the transfer medium 8. When the toner image is transferred to the intermediate transfer medium, the toner image on the intermediate transfer medium is further transferred to the transfer paper, and then the toner image on the transfer paper is fixed by a fixing device (not shown) to form an image on the transfer paper. Is done.

  The cleaning device 7 has a cleaning blade 7a made of an elastic material such as rubber. The cleaning blade 7a is supported by an L-shaped blade support member 7b. In this case, as shown in FIG. 2, the blade support member 7 b is attached to the apparatus main body (or cartridge main body) 10 so as to be rotatable about the rotation shaft 9. Further, a tension spring 11 is stretched between the blade support member 7b and the apparatus main body 10, and the tension spring 11 causes the blade support member 7b to be constantly urged clockwise in FIG. Has been. As a result, the cleaning blade 7 a is always in pressure contact with the outer peripheral surface of the photoreceptor 2. The photoconductor 2 is cleaned by the cleaning blade 7a, and the untransferred toner on the photoconductor 2 is removed and recovered by the toner recovery portion 7c.

  In the image forming apparatus 1 of this example, the brush support member 3 of the charging brush 3d is attached to the blade support member 7b of the cleaning blade 7a. That is, the charging brush 3d and the cleaning blade 7a are integrated. The charging brush 3d is always in pressure contact with the outer peripheral surface of the photoreceptor 2 with a predetermined amount of biting by the urging force of the tension spring 11. A point where a straight line γ connecting the rotation center A of the photoreceptor 2 and the center B of the rotation shaft 9 of the blade support member 7b intersects with the outer peripheral surface of the photoreceptor 2 is defined as an intersection E. Then, a contact point C between the conductive elastomer layer 3c of the charging roller 3a and the photosensitive member 2 is set downstream of the intersection E in the rotation direction α of the photosensitive member 2. Further, the contact point D of the charging brush 3d with the photosensitive member 2 is downstream of the contact point F of the cleaning blade 7a with the photosensitive member 2 in the rotational direction α of the photosensitive member 2 and upstream of the crossing point E in the rotational direction α. Is set to

In the image forming apparatus 1 of this example configured as described above, when the photosensitive member 2 rotates in the rotation direction α during image formation, the cleaning blade 7a pressed against the photosensitive member 2 performs a stick-slip motion. Due to this stick-slip motion, the cleaning blade 7a vibrates, and this vibration is transmitted to the charging brush 3d via the blade support member 7b and the brush support member 3, so that the charging brush 3d also vibrates. Due to the vibration of the charging brush 3d, toner and foreign matter adhering to the charging brush 3d are shaken off. As a result, contamination of the charging brush 3d due to toner or foreign matter is removed, and the charging property is improved.
The overall image forming operation of the image forming apparatus 1 in this example is the same as the image forming operation of the conventional general image forming apparatus 1, and thus the description thereof is omitted.

According to the image forming apparatus 1 of this example, since the brush support member 3 of the charging brush 3d is attached to the blade support member 7b of the cleaning blade 7a, the charging is performed by the stick-slip motion of the cleaning blade 7a generated during the image forming operation. The brush 3d can be vibrated. Due to this vibration, the toner and foreign matter adhering to the charging brush 3d are shaken off, so that the contamination of the charging brush 3d due to the toner and foreign matter can be removed and the charging property can be improved. Therefore, it is possible to charge the photoreceptor 2 with the charging brush 3d satisfactorily over a long period of time and to obtain a high-quality image.
In addition, since a dedicated cleaning member for removing dirt on the first charging member is not required, the number of parts can be reduced, and the configuration of the charging device can be simplified.

FIG. 3 is a view similar to FIG. 2 showing another example of the embodiment of the image forming apparatus of the present invention.
In the image forming apparatus 1 of the example shown in FIG. 2, the contact point C between the conductive elastomer layer 3c of the charging roller 3a and the photoreceptor 2 and the contact point D between the photoreceptor 2 of the charging brush 3d are photosensitive. The straight line γ connecting the rotation center A of the body 2 and the rotation center B of the blade support member 7b is set on the opposite side. On the other hand, as shown in FIG. 3, in the image forming apparatus 1 of this example, the contact point C of the charging roller 3a with the photosensitive member 2 and the contact point D of the charging brush 3d with the photosensitive member 2 are linear γ. Both are set on the same side. That is, both contact points C and D are located downstream from the intersection E in the rotational direction α. Further, the contact point F of the cleaning blade 7a with the photoreceptor 2 is set on the opposite side of the contact point D of the charging brush 3d with the photoreceptor 2 with respect to the straight line γ.

In order to arrange the contact points C, D, E in this way, in the image forming apparatus 1 of this example, the rotation center B of the blade support member 7b is the rotation center B of the blade support member 7b of the example shown in FIG. More provided on the cleaning blade 7a side.
In the image forming apparatus 1 of this example configured as described above, the cleaning blade 7a is bent flexibly by long-term image formation. Then, the blade support member 7b rotates counterclockwise around the rotation center B in FIG. 3 according to the deflection amount of the cleaning blade 7a. By the rotation of the blade support member 7b, the charging brush 3d moves in a direction in which the amount of biting decreases, and the pressure contact force of the charging brush 3d to the photosensitive member 2 is reduced.

  According to the image forming apparatus 1 of this example, the contact point F of the cleaning blade 7a is set on the side opposite to the contact point D of the charging brush 3d with respect to the straight line γ, so that it corresponds to the durable deflection of the cleaning blade 7a. The amount of biting of the charging brush 3d into the photoreceptor 2 can be reduced. Therefore, film abrasion of the photoreceptor 2 due to the pressure contact of the charging brush 3d can be suppressed, and the life of the apparatus can be extended.

Further, by providing the rotation center B of the blade support member 7b on the cleaning blade 7a side, the pressure contact force of the cleaning blade 7a can be increased. In other words, the urging force of the tension spring 1 that presses the cleaning blade 7a against the photosensitive member 2 can be reduced.
Other configurations and other functions and effects of the image forming apparatus 1 of this example are the same as those of the example shown in FIG.

FIG. 4 is a view similar to FIG. 2, showing still another example of the embodiment of the image forming apparatus of the present invention.
In the image forming apparatus 1 of the example shown in FIG. 2 described above, the charging brush 3d is supported by the blade support member 7b via the brush support member 3e. On the other hand, as shown in FIG. 4, in the image forming apparatus 1 of this example, the charging brush 3d is directly supported on the cleaning blade 7a by an adhesive or the like.
According to the image forming apparatus 1 of this example, the brush support member 3e is unnecessary, the number of parts is smaller than that of the example shown in FIG. 2, and the configuration can be made compact.
Other configurations and other functions and effects of the image forming apparatus 1 of this example are the same as those of the example shown in FIG.

  In each of the above-described examples, the charging brush 3d is used as the first charging member, but another member such as a roller or pad made of sponge, foamed urethane foam or felt may be used as the first charging member. it can. Similarly, the charging roller 3a is used for the second charging member, but other similar members can be used for the second charging member.

1 is a diagram schematically and partially showing an example of an embodiment of an image forming apparatus according to the present invention. FIG. 1 schematically shows the example photoreceptor, charging device, and cleaning device shown in FIG. It is a figure showing other examples of an embodiment of an image forming device concerning the present invention typically and partially. FIG. 10 is a diagram schematically and partially showing still another example of the embodiment of the image forming apparatus according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Photoconductor, 3 ... Charging device, 3a ... Charging roller (second charging member), 3c ... Conductive elastomer layer, 3d ... Charging brush (first charging member), 3e ... Brush support member , 7 ... Cleaning device, 7a ... Cleaning blade, 7b ... Blade support member, 9 ... Rotating shaft, A ... Rotation center of photoconductor, B ... Rotation center of cleaning blade, C ... Contact point of charging roller to photoconductor , D: contact point of charging brush to photoreceptor, E: contact point of cleaning blade to photoreceptor, γ: straight line connecting both rotation centers A and B

Claims (5)

A first contact charging member that is rotatably provided and contacts the image carrier to charge the surface of the image carrier;
A second contact charging member that contacts the image carrier downstream of the first contact charging member in the rotation direction of the image carrier and charges the surface of the image carrier;
A cleaning blade that contacts the surface of the image carrier and cleans the surface;
A blade support member provided rotatably and supporting the cleaning blade;
At least a charging member support member for supporting the first contact charging member,
A charging device, wherein the charging member supporting member is attached to the blade supporting member. A first contact charging member that is rotatably provided and contacts the image carrier to charge the surface of the image carrier;
A second contact charging member that contacts the image carrier downstream of the first contact charging member in the rotation direction of the image carrier and charges the surface of the image carrier;
A cleaning blade that contacts the surface of the image carrier and cleans the surface;
A blade support member provided rotatably and supporting the cleaning blade;
At least a charging member support member for supporting the first contact charging member,
A charging device, wherein the charging member supporting member is attached to the cleaning blade. 3. The charging device according to claim 1, wherein a charging brush is used for the first contact charging member. The contact point of the cleaning blade with the image carrier is set upstream of the straight line connecting the rotation center of the image carrier and the rotation center of the cleaning blade in the rotation direction of the image carrier. 4. The charging device according to claim 1, wherein a contact point of the charging member to the image carrier is set downstream of the straight line in a rotation direction of the image carrier. 5. An image carrier that is rotatably provided to form an electrostatic latent image, a charging device that charges the image carrier, a writing device that writes an electrostatic latent image on the image carrier, and the image carrier At least a developing device for developing the electrostatic latent image on the image carrier to form a developer image on the image carrier, and a transfer device for transferring the developer image on the image carrier;
An image forming apparatus, wherein the charging device is the charging device according to claim 1.

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