JPH05341629A - Electrifying device for image forming device - Google Patents

Abstract

PURPOSE:To realize a durable and inexpensive electrifying device by which a good-quality image is obtained by automatically removing residual toner sticking to the conductive fiber of an electrostatic charging member, and preventing irregular electrification on a photosensitive body. CONSTITUTION:This device is provided with an electrostatic charging roller 5 whose surface is constituted of the conductive fiber part 5a, and a stain preventing member 25 provided in the longitudinal direction of the roller 5 so that it may be uniformly brought into contact with and freely separated from the roller 5. When the electrifying device is operated, the member 25 is uniformly brought into contact with the conductive fiber of the surface of the roller 5 so as to remove the residual toner sticking to the surface of the conductive fiber part 5a of the roller 5. When the electrostatic charging device is not operated, the member 25 is separated from the roller 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device of an image forming apparatus which forms a main part of a copying machine, a printer, a facsimile, etc., which is formed by applying an electrophotographic technique.

[0002]

2. Description of the Related Art Generally, as an image forming apparatus of a device to which electrophotographic technology is applied, such as a copying machine, there is a charging device for charging a surface of a photoconductor (or an image carrier). Conventionally, there are various types of such charging devices. Regarding this device, a charging member made of conductive fibers is used, and the tip of the conductive fibers is brought into contact with the surface of the photoconductor to The method of charging the toner is disclosed in "JP-A-55-29837-Charger"
Has been proposed by.

As the constitution of the charging member, there have been devised ones in which fibers are bonded to a conductive substrate such as aluminum, and ones in which conductive fibers are wound around a conductive core member.

[0004]

However, in the case where the electrically conductive fiber body is used as the charging member, the charging member is provided on the surface of the photoconductor (image carrier surface) for a long time regardless of the structure. Upon contact, residual toner remaining on the surface of the photoconductor without being removed by the cleaning blade adheres to the tips (eg, hair tips) of the conductive fibers of the charging member, and as a result, toner adheres to the tips. Since the conductive fiber slides relatively on the surface of the photoconductor as it is, the surface of the photoconductor is scratched, and abnormal discharge or defective discharge occurs at the contact part, resulting in uneven charging in the form of brushes or stripes. Occurs on the image and deteriorates the image quality. In addition, when the charging member is brought into contact with the surface of the photoconductor for a long time, the conductive fiber portion of the charging member is tilted in the rotation direction of the photoconductor to cause "fiber sag", and the conductive fiber is separated from the surface of the photoconductor. There is a problem in that uneven contact may occur due to non-uniform contact and uneven charging.

Further, there is a problem that the adhesion of the toner to the tip of the conductive fiber causes deterioration of the durability of the charging member itself. It is an object of the present invention to provide a charging device for an image forming apparatus, which is inexpensive and durable, which can solve the above-mentioned conventional problems and can obtain a high quality image.

[0006]

In order to solve the above-mentioned problems, the present invention has, as a main structure of a charging device, a charging roller having a surface made of a conductive fiber, and a charging roller in the longitudinal direction of the charging roller. Along with the charging roller, the dirt prevention member that can be uniformly contacted and separated from each other and the charging device that contacts the photoconductor with the charging roller are operated by uniformly contacting the dirt prevention member with the conductive fibers on the surface of the charging roll. The conductive fibers on the roller surface are cleaned, and when the image forming device is not operating,
A means for separating the stain prevention member from the charging roller is provided.

[0007]

With the above-described structure, the residual toner or foreign matter attached to the conductive fibers can be scraped off by the stain preventing member when the apparatus is in operation, and the conductive fibers can be upright when the apparatus is not in operation. ..

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. 1A and 1B are perspective views of a main part of a charging device according to an exemplary embodiment of the present invention. FIG. 1A shows a state when the image forming apparatus is in operation, and FIG. Shows the status during operation. FIG. 2 shows a stain prevention member which is one of the main constituent elements of the present invention.

As shown in FIG. 1, the charging device mainly has a charging roller 5 and a stain preventing member 25. That is, the charging roller 5 includes a conductive base material 5b and a conductive fiber portion 5a made of a conductive fiber brush or cloth provided on the surface thereof.
It is composed of and. Further, as shown in FIGS. 1 and 2, the stain prevention member 25 is provided in the longitudinal axis direction of the charging roller 5 and the longitudinal direction of the photoconductor 1, and the fixed shafts 25c, 2c.
5d and the supporting portion 25b apart from the fixed shafts 25c and 25d.
The cleaning section 25b and the cleaning section 25b have a long and integrated shape. Furthermore, a solenoid 21, a spring 22, a bar 23, and an elliptical roller 24 are provided using the charging roller 5 and the stain prevention member 25 as operating members. The photosensitive drum 1 is composed of a charged portion 1a, which is a photosensitive layer at the center in the axial direction, and an uncharged portion 1b, which is an aluminum drum at both ends in the axial direction.

During operation of the charging device, the solenoid 21 operates as shown in FIG. 1A, the spring 22 is extended and the bar 23 is pulled down, and the elliptical roller 24 is rotated. The charging roller 5 is supported by, and the stain preventing member 25 connected to the bar 23 via the elliptical roller 24 is rotated.

Since the portion of the support portion 25b of the stain prevention member 25 is disengaged from the aluminum drum of the non-charged portion 1b of the photoconductor 1 by the rotation of the stain prevention member 25, the charging roller 5 is moved as shown in FIG. The conductive fiber portion 5a on the surface of the charging roller 5 moves downward and the photosensitive layer 1 of the photosensitive member 1
The conductive fiber portion 5 that comes into contact with a and rotates the portion of the cleaning portion 25a of the stain prevention member together with the photoreceptor 1.
a will be relatively tapped.

Next, when the charging device is stopped, as shown in FIG.
Solenoid 21 is stopped and spring 22
The bar 23 is pulled up and the elliptical roller 24 is rotated, the charging roller 5 is supported in the major axis direction of the elliptical roller 24, and the stain preventing member 25 is rotated, so that the supporting portion 25b is the non-charging portion 1b of the photoreceptor 1. The charging roller 5 is pushed up by contacting with the aluminum drum, and the photoconductor 1 and the charging roller 5 are separated from each other.

Next, a specific embodiment of the image forming apparatus provided with the charging device of the present invention will be described with reference to FIG. In the image forming apparatus, image data is first sent to the controller board 16 from a host computer (not shown). At this time, a signal for starting each process for forming an image is output from the engine controller 17,
When this signal is output, each step is operated in accordance with the step input in advance.

The operation description of each specific process will be listed. First, the paper is fed by the paper feed roller 8 and conveyed to the registration rollers 11 by the conveyance rollers 9 and 10.

At this time, a voltage is applied to the charging roller 5 whose surface is made of conductive fiber, and the charging roller 5 contacts the photoconductor 1 to uniformly charge the surface to a desired potential.

In the developing device 2, the magnet roller 2d is used.
Toner tank 2e so that the upper toner has a predetermined density
The toner is supplied from and is stirred by the mixer 2c.

At this time, the toner is charged to the same polarity as the charge potential of the photoconductor 1, and the exposure writing head 6 is irradiated with light by applying a voltage close to the charge potential of the photoconductor 1 to the magnet roller 2d. Toner adheres to the surface of the photoconductor 1 and develops.

The paper fed in front of the registration roller 11 is sent to the transfer roller 3 at a timing corresponding to the image position of the photoconductor 1 and after the developed image on the photoconductor 1 is transferred. The transferred image is fixed by passing between the heat roller 12a and the pressure roller 12b, and is discharged by the transport roller 13 and the paper discharge roller 14.

[0019]

As described above, in the charging device of the present invention, at least the surface of the charging roller is made of conductive fiber, and the charging roller is uniformly contacted with and separated from the charging roller along the longitudinal direction of the charging roller. Since the dirt prevention member and the means for contacting and separating the dirt prevention member from the charging roller are provided, the dirt prevention member can scatter residual toner and foreign matter adhered to the conductive fibers on the surface of the charging roller during operation of the charging device. It is possible to prevent uneven charging and generation of scratches on the surface of the photoconductor, which are caused by the conductive fibers of the conventional charging roll contacting the image bearing surface of the photoconductor with the residual toner adhering thereto. Images can be obtained.

Further, when the charging device is not in operation, the conductive fibers are separated from the photosensitive member to be in an upright state to prevent the fibers from being settled, thereby preventing the charging unevenness from occurring and the durability of the fibers and the device. It is possible to obtain an excellent effect such that an inexpensive and reliable charging device can be provided.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part of an “charging device for an image forming apparatus” of the present invention, where FIG. 1A shows a state when the apparatus is in operation, and FIG. 1B shows a state when the apparatus is stopped. It is explanatory drawing which shows a state.

FIG. 2 is a structural explanatory view of a “dirt prevention member” which is one of the main constituent elements of the present invention.

FIG. 3 is a vertical cross-sectional view of the image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 1a Photosensitive layer of charged part 1b Aluminum drum of non-charged part 3 Transfer roller 5 Charging roller 5a Conductive fiber part 5b Conductive base material 21 Solenoid 22 Spring 23 Bar 24 Elliptical roller 25 Stain prevention member 25a Cleaning part 25b Support Part 25c, 25d Fixed shaft

Claims (1)

[Claims] 1. A charging device for an image forming apparatus to which an electrophotographic technique is applied, wherein a charging roller having at least a surface made of a conductive fiber, and a charging roller provided along the longitudinal direction of the charging roller are uniformly provided. When the anti-fouling member which can be freely contacted and separated and the charging device in which the charging roller contacts the photoconductor are operated, the anti-fouling member is brought into uniform contact with the conductive fiber on the surface of the charging roller to make the conductive fiber of the charging roller. A charging device for an image forming apparatus, which is provided with means for cleaning the surface of the charging device and for separating the stain preventing member from the charging roller when the charging device is not operating.