JP2001337559A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of preventing leak even in a state where the bristles of a conductive brush forming a ground path are caught in space between a photoreceptor pipe stock and a flange. SOLUTION: This image forming device 1 is equipped with an image carrier 5 on whose surface an electrostatic latent image corresponding to an original image is formed by exposure, the conductive brush held inside the image carrier 5 and forming a part of the ground path for discharging the charge of an exposed part on the surface of the image carrier 5, a conductor 7 positioned to be opposed to the image carrier 5, and an insulating member 47 provided between the image carrier 5 and the conductor 7 and preventing the bristles 34a of the conductive brush exposed from the image carrier 5 from coming into contact with the conductor 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Generally, in an image forming apparatus utilizing an electrophotographic process, an electrostatic latent image corresponding to a document image is formed on the surface of a photoreceptor charged to a predetermined polarity in advance. This electrostatic latent image is developed by a developing unit provided at a predetermined position around the photoconductor. That is, the electrostatic latent image is developed and visualized by the charged fine powder toner supplied from the developing unit. The toner image formed on the photoreceptor reaches the transfer unit by rotation of the photoreceptor, and is transferred to a transfer material (recording paper) conveyed to the transfer unit. afterwards,
The toner image transferred to the transfer material is fixed to the transfer material in a fixing unit.

When an electrostatic latent image is formed on the surface of a photoreceptor by performing exposure, it is necessary to satisfactorily release surface charges at the exposed portion through a ground path. For example, Japanese Patent Application Laid-Open No. Hei 9-114168 discloses a technique in which a conductive brush held inside a photoconductor is used as a part of the ground path.

[0004]

The conductive brush disclosed in the above-mentioned publication has excellent stability due to the large number of contact points, but the conductive brush is not easily transported during transportation or during the assembly process of the photosensitive member. Brush hairs may come off or break. As shown in FIG. 7, the photosensitive member 100 has a cylindrical conductive substrate (hereinafter, referred to as a photosensitive member tube) 102 having a photosensitive layer formed on a surface thereof, and a resin flange connected to a rotary drive shaft. 104, and is formed by press-fitting the flange 104 inside the photoreceptor tube 102. However, during the process of press-fitting the flanges 104 at both ends of the photoreceptor tube 102, the flange 104 When the brush bristles 105 are exposed while being sandwiched between the photoreceptor base tube 102 and the flange 104, the brushes exposed to conductive portions such as a charging roller and a transfer roller approaching the photoreceptor 100 and approaching the same. There is a possibility that the hairs 105 come into contact with each other and a leak occurs to cause an abnormal image. It is very difficult to prevent the brush hair from coming off or being cut off,
As shown in FIG. 7, it is costly to select the photoconductor 100 in which the brush bristles 105 are interposed.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a state in which the brush bristles of a conductive brush forming an earth path are sandwiched between a photosensitive drum and a flange. However, an object of the present invention is to provide an image forming apparatus capable of preventing a leak.

[0006]

According to another aspect of the present invention, there is provided an image forming apparatus, comprising: an image carrier on which an electrostatic latent image corresponding to a document image is formed by exposure; A conductive brush that is held inside the image carrier and forms a part of a ground path for releasing charges of an exposed portion of the surface of the image carrier, and a conductor that is positioned opposite to the image carrier. The distance between the image carrier and the conductor is set to be longer than the length of the bristle of the conductive brush.

According to the first aspect of the present invention, the distance between the image carrier and the conductor is set to be longer than the length of the bristles of the conductive brush. The brush hairs and the conductor do not come into contact with each other even if they are exposed, and therefore, the occurrence of an abnormal image due to leakage can be reliably prevented.

[0008] The image forming apparatus according to claim 2 is
One of an image carrier on which an electrostatic latent image corresponding to a document image is formed by exposure, and a ground path which is held inside the image carrier and discharges an electric charge at an exposed portion of the surface of the image carrier. A conductive brush forming a portion, a conductive member positioned opposite to the image carrier, and a brush bristles and a conductive member of the conductive brush provided between the image carrier and the conductive member and exposed from the image carrier. And an insulating member for preventing the contact with the insulating member.

According to the second aspect of the present invention, since the insulating member is provided between the image carrier and the conductor,
Even when the brush bristles of the conductive brush are exposed from the image carrier, contact between the brush bristles and the conductor is prevented by the insulating member. Therefore, occurrence of an abnormal image due to a leak can be prevented.

The image forming apparatus according to claim 3 is
3. The image forming apparatus according to claim 2, wherein the insulating member also serves as a bearing that rotatably supports the conductor.

According to the third aspect of the present invention, since the insulating member also serves as the bearing, the number of parts and the cost do not need to be increased.

[0012] The image forming apparatus according to claim 4 is
3. The image forming apparatus according to claim 2, wherein the insulating member also serves as a regulating member for positioning the conductor with respect to the image carrier.

According to the fourth aspect of the present invention, since the insulating member also serves as the regulating member, it is not necessary to increase the number of parts and the cost.

The image forming apparatus according to a fifth aspect of the present invention provides
5. The image forming apparatus according to claim 2, wherein the insulating member is provided only on one end side of the image carrier on which the conductive brush is disposed. 6. .

According to the fifth aspect of the present invention, since the insulating member is provided only on one end side of the image carrier, the cost can be minimized.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of an image forming apparatus 1 according to an embodiment of the present invention. As shown in the drawing, the image forming apparatus 1 includes, for example, a reading unit that irradiates a document placed on a contact glass with light and reads reflected light (image information) of the document. A laser optical system having a writing unit 3 for outputting a laser beam based on the laser beam and a mirror for guiding the laser beam in a predetermined direction is provided. Further, the image forming apparatus 1 has a photoconductor 5 as an image carrier on which a laser beam is irradiated to form an electrostatic latent image corresponding to image information on the surface.

A charging device (charging roller) 7 for charging the surface of the photoreceptor 5 is provided around the photoreceptor 5 rotating in the direction of the arrow in the figure, and an electrostatic latent image formed on the surface of the photoreceptor 5 is formed. By supplying toner to visualize the electrostatic latent image, the photosensitive member 5
A developing device 9 for forming a toner image thereon, a transfer device (transfer roller) 11 for transferring the toner image on the photoconductor 5 to a sheet 19 as a transfer material, Cleaning device 13 for cleaning in preparation for
Are provided.

On the lower side of the image forming apparatus 1, there is provided a sheet feeding device 17 having a sheet feeding tray detachably attached to the apparatus main body. Further, the image forming apparatus 1 transfers the paper 19 fed from the paper feeding device 17 to the transfer device 1.
1, a pair of registration rollers 21 and 23 sent out at a predetermined timing, a fixing device 25 for fixing the toner image transferred to the sheet 19 by the transfer device 11, and the sheet 19 subjected to the fixing process. A paper discharge tray 27 is provided. The fixing device 25 has a fixing roller having a built-in heater, and a pressure roller pressed against the fixing roller, and fixes the toner image on the sheet 19 passing between the rollers by the heat of the heater. The paper 19 on which the toner image has been fixed by the fixing device 25 is discharged onto the paper discharge tray 27 with the image side down.

As shown in FIG. 2, the photosensitive member 5 has a cylindrical conductive base (hereinafter, referred to as a photosensitive body tube) 30 having a photosensitive layer formed on its surface and a resin connected to a rotary drive shaft. And a press-fitting flange 32 into both ends of the photosensitive element tube 30.

In the present embodiment, the conductive brush 34 is used as a part of the earth path for releasing the electric charge of the exposed portion of the surface of the photoconductor 5. The conductive brush 34 is integrally held on one flange 32 by using a conductive ground plate 36. The conductive brush 34 includes a conductive fiber portion (hereinafter, referred to as brush bristles) 34a and a conductive holding portion 34b that holds them, and is held in contact with the ground plate 36. . In addition, a support pin 37 that is connected to a ground portion of the machine main body is inserted through a center hole of the flange 32, and the photoconductor 5 is rotatably supported by the support pin 37.

The ground path of the photoreceptor 5 includes an inner peripheral surface 30a of the photoreceptor tube 30 and a plurality of protrusions formed on the outer edge of the ground plate 36 and in contact with the inner peripheral surface 30a of the photoreceptor tube 30. A conductive brush 34 that comes into contact with the ground plate 36, and a bristle 34 a of the conductive brush 34
, And is connected to the ground portion of the machine body via the support pin 37.

By the way, in the process of press-fitting the flange 32 into the end of the photoreceptor tube 30, as shown in FIG. When exposed in a state sandwiched between them, the brush bristles 34 a exposed as, for example, the charging roller 7 as a conductor that rotates in conjunction with the photoconductor 5 in opposition to the photoconductor 5 come into contact with the photoconductor 5, causing a leak to occur and an abnormal image May cause. Therefore, in the image forming apparatus 1 of the present embodiment, a device for avoiding such a situation is devised.

That is, in the present embodiment, as shown in FIG. 3, the brush bristles 34a of the conductive brush 34 are interposed between the photoreceptor 5 and the charging roller 7 (specifically, it is assumed). An insulating member 47 for preventing contact between the brush bristles 34a and the charging roller 7 is provided at a position facing the end of the photosensitive drum 30. The insulating member 47 is made of an electrically insulating material, and is formed as a bearing that rotatably supports the metal core 7 a of the charging roller 7. In order to bring the charging roller 7 into contact with the photoconductor 5 at a predetermined pressure, the insulating member 47 supporting the charging roller 7 is constantly urged toward the photoconductor 5 by a pressure spring 48.
The bias applied to the charging roller 7 is directly applied to the metal core 7 a via the leaf spring 49. FIG. 3 shows only the configuration of one end of the photoconductor 5, but the other end of the photoconductor 5 has the same configuration as that of FIG.

As described above, in the image forming apparatus 1 of the present embodiment, between the photoreceptor 5 and the charging roller 7 (the brush bristles 34a of the conductive brush 34 are assumed to be interposed).
An insulating member 47 is provided at a position facing the end of the photosensitive drum 30).
Is provided. Therefore, even if the brush bristles 34a of the conductive brush 34 are caught between the ends of the photosensitive element tube 30, the contact between the brush bristles 34a and the charging roller 7 is prevented by the insulating member 47, so that an abnormal image due to leakage occurs. Can be prevented. Further, in the present embodiment, the insulating member 47 also serves as a bearing for rotatably supporting the metal core 7a of the charging roller 7, so that the number of parts and the cost need not be increased.

FIG. 4 shows a second embodiment of the present invention. In the present embodiment, a contact preventing member 52 for preventing contact between the brush bristles 34a of the conductive brushes 34 and the charging roller 7 is provided separately from the bearing 50 that rotatably supports the core metal 7a of the charging roller 7. I have. This contact prevention member 52
Is made of an electrically insulating material, and is fitted to the bearing 50. Therefore, it does not rotate with the charging roller 7. Since the other configuration is the same as that of the first embodiment, the same reference numerals are given and the description is omitted.

FIG. 5 shows a third embodiment of the present invention. Note that, in this embodiment, the same components as those in the first and second embodiments are denoted by the same reference numerals, and description thereof is omitted.

As shown, in the present embodiment, the distance A between the photosensitive member 5 and the metal core 7a of the charging roller 7 is set to be longer than the length B of the brush bristles 34a of the conductive brush 34. I have. Therefore, the brush bristles 34a do not come into contact with the metal core 7a without providing an insulating member as in the first and second embodiments. That is, the brush bristles 3
4a is caught between the ends of the photoreceptor tube 30, the brush bristles 3
Since 4a does not come into contact with the charging roller 7, the occurrence of an abnormal image due to leakage is reliably prevented. Further, in this configuration, the bearing 50 can be formed of a conductive resin and a bias can be applied to the charging roller 7 via the pressure spring 48, so that the degree of freedom in design is improved.

FIG. 6 shows a fourth embodiment of the present invention. Note that, in this embodiment, the same components as those in the first to third embodiments are denoted by the same reference numerals, and description thereof is omitted.

As shown, in this embodiment, the photosensitive member 5
The brush bristles 34a are located between the transfer roller (conductor) 11 and, more specifically, at a position opposed to the end of the photosensitive body tube 30 where the brush bristles 34a of the conductive brush 34 are sandwiched (assumed). Insulating member 6 for preventing contact between transfer roller 11 and transfer roller 11
0 is provided. Also, the core metal 11 of the transfer roller 11
a is rotatably supported by a bearing 57. In order to bring the transfer roller 11 into contact with the photoconductor 5 at a predetermined pressure, a bearing 57 supporting the transfer roller 11 is used.
Is always urged toward the photoreceptor 5 by a pressure spring 58. Transfer roller 1 due to urging force of spring 58
The amount of bite of the first photoconductor 5 is regulated by the insulating member 60 abutting against the photosensitive layer uncoated portion 5 a provided at the end of the photoconductor 5. That is, the insulating member 60 also functions as a regulating member that performs positioning (position regulation) of the transfer roller 11 with respect to the photoconductor 5. The insulating member 60 covers the metal core 11 a of the transfer roller 11 up to the end of the photoconductor 5.

As described above, in the present embodiment, the photoconductor tube 30 is assumed to be located between the photoconductor 5 and the transfer roller 11 (the brush bristles 34a of the conductive brushes 34 are assumed to be interposed therebetween).
The insulating member 60 is provided at a position facing the end of the insulating member 60). Therefore, even if the brush bristles 34a of the conductive brush 34 are pinched between the ends of the photosensitive element tube 30, the contact between the brush bristles 34a and the transfer roller 11 is prevented by the insulating member 60, so that an abnormal image is generated due to leakage. Can be prevented. Further, in the present embodiment, the insulating member 60 also serves as a regulating member that positions (regulates the position of) the transfer roller 11 with respect to the photoconductor 5, so that the number of parts and the cost do not need to be increased.

The present invention is not limited to the above-described embodiment, but can be variously modified without departing from the scope of the invention. For example, in the above-described embodiment, the present invention is applied between the photoconductor and the charging roller or the transfer roller. However, the present invention is also applied between the photoconductor and another conductor facing and close to the photoconductor. It goes without saying that it can be applied. Further, in the above-described embodiment, the present invention is applied to both ends of the photoconductor, but the present invention may be applied to only one end of the photoconductor. That is, the problem that the brush bristles of the conductive brush are caught is that the flange is press-fitted into the photoreceptor tube while the brush bristles that have come off or cut off adhere to the flange where the conductive brush is integrally provided. This is a problem that can occur only on the side of the flange on which the brush is provided. Therefore, if the present invention is applied only to the flange side (one end side of the photoconductor) on which the brush is provided, the cost can be reduced.

[0033]

According to the first aspect of the present invention, since the distance between the image carrier and the conductor is set to be longer than the length of the brush bristles of the conductive brush, the brush bristles can carry the image. Even when exposed from the body, the brush hairs and the conductor do not come into contact with each other, so that the occurrence of an abnormal image due to leakage can be reliably prevented.

According to the second aspect of the present invention, since the insulating member is provided between the image carrier and the conductor, even if the bristles of the conductive brush are exposed from the image carrier, the brush can be used. The contact between the hair and the conductor is prevented by the insulating member. Therefore, occurrence of an abnormal image due to a leak can be prevented.

According to the third aspect of the present invention, since the insulating member also serves as the bearing, the number of parts and the cost do not need to be increased.

According to the fourth aspect of the invention, since the insulating member also serves as the regulating member, it is not necessary to increase the number of parts and the cost.

According to the fifth aspect of the present invention, since the insulating member is provided only at one end of the image carrier on which the conductive brush is disposed, the cost can be minimized. .

[Brief description of the drawings]

FIG. 1 is an overall view of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of a photoconductor of the image forming apparatus of FIG.

FIG. 3 is an enlarged perspective view of a main part of the first embodiment.

FIG. 4 is an enlarged perspective view of a main part of an image forming apparatus according to a second embodiment of the present invention.

FIG. 5 is an enlarged perspective view of a main part of an image forming apparatus according to a third embodiment of the present invention.

FIG. 6 is an enlarged perspective view of a main part of an image forming apparatus according to a fourth embodiment of the present invention.

FIG. 7 is a perspective view showing a state in which the bristle of the conductive brush is exposed from the photoconductor.

[Explanation of symbols]

 Reference Signs List 1 image forming apparatus 5 photoreceptor (image carrier) 7 charging roller (conductor) 11 transfer roller (conductor) 34 conductive brush 34a brush bristles 47, 52, 60 insulating member

Claims (5)

[Claims] An image carrier on which an electrostatic latent image corresponding to a document image is formed by exposure; and an image carrier which is held inside the image carrier and charges an exposed portion of the surface of the image carrier with an electric charge. A conductive brush forming a part of a ground path to escape, and a conductor positioned opposite to the image carrier, wherein a distance between the image carrier and the conductor is equal to the length of the bristle of the conductive brush. The image forming apparatus is set to be larger than the threshold value. 2. An image carrier on which an electrostatic latent image corresponding to a document image is formed by exposure, and an image carrier that is held inside the image carrier, and charges an exposed portion of the surface of the image carrier with an electric charge. A conductive brush forming a part of a ground path for escape, a conductive member positioned opposite to the image bearing member, and a conductive brush provided between the image bearing member and the conductive member and exposed from the image bearing member. An image forming apparatus comprising: an insulating member for preventing contact between a brush bristle and a conductor. 3. The image forming apparatus according to claim 2, wherein the insulating member also serves as a bearing that rotatably supports the conductor. 4. The image forming apparatus according to claim 2, wherein the insulating member also functions as a regulating member for positioning the conductor with respect to the image carrier. 5. The image forming apparatus according to claim 2, wherein the insulating member is provided only on one end side of the image carrier on which the conductive brush is arranged. Image forming apparatus.