JPH09138564A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute development with toner by simple constitution by constituting a means for electrifying the surface of a photoreceptor and a means for carrying the developer on the surface of the photoreceptor of the same member. SOLUTION: This device is provided with the photoreceptor drum 10 being an image carrier and a process blade 11 electrifying the surface of the drum 10 at uniform potential so as to stick the toner being developer to the drum 10. Charge electrified by the process blade 11 is discharged at a part irradiated with a laser beam on the surface of the drum 10 by a scanner unit 14 selectively radiating the laser beam in accordance with image data, so that an electrostatic latent image is formed under a toner layer. When transfer paper 16 being a recording medium is carried between the drum 10 and a transfer roller 15 by a carrying mechanism, the toner stuck to the drum 10 is selectively transferred on the transfer paper in accordance with image information, so that a toner image is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus used in an electrophotographic recording apparatus and the like, and more particularly to an image forming apparatus using a non-magnetic one-component toner as a developer.

[0002]

2. Description of the Related Art Non-magnetic one-component toner (hereinafter referred to as "toner")
That. In general, an image forming apparatus having a developing device that uses) as a developer has a photoconductor as an image carrier, a charging unit that charges the surface of the photoconductor to a uniform potential, and image information input from the outside. And a developing means for exposing the photosensitive member to form an electrostatic latent image on the photosensitive member based on the above, and further developing by attaching charged toner to the electrostatic latent image formed on the photosensitive member. A developing device is provided with a supplying device for supplying the toner to the developing device and a friction charging device for giving an electric charge to the toner supplied to the developing device.

As a charging means of such a developing device,
A scorotron or the like for charging by corona discharge is used, and a scanner unit or the like for performing exposure by irradiating a laser beam is used as the exposure means. An elastic roller (hereinafter referred to as "developing roller") or the like is used as the developing means. A predetermined voltage (hereinafter, referred to as "bias") is applied to the developing roller, which plays a role of adhering toner to the electrostatic latent image formed on the photoconductor and conveying the electrostatic latent image to the developing area. As a supply unit, another roller (hereinafter, referred to as “supply roller”) for conveying and adhering toner to the developing roller.
Is used. A bias may be applied to the supply roller in order to adjust the amount of toner adhered to the developing roller. An elastic blade (hereinafter, referred to as "charging blade") that is pressed against the developing roller is used as the friction charging unit. The charging blade frictionally charges the toner passing between the charging blade and the developing roller to give an electric charge.

[0004]

However, in the developing device and the like as described above, it is necessary to dispose the scorotron, the developing roller, the supply roller, the charging blade and the like inside the developing device and the like in addition to the photoconductor. Therefore, these devices have a complicated structure, which hinders the downsizing and cost reduction of the devices.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an image forming apparatus capable of developing with toner with a simple structure.

[0006]

In order to achieve the above object, an image forming apparatus according to a first aspect of the present invention provides a photoconductor on which an electrostatic latent image is formed according to image information, and a surface of the photoconductor to a predetermined potential. Charging means for electrically charging the surface of the photoconductor, a developer carrying means for carrying a developer on the surface of the photoconductor, an exposing means for exposing the surface of the photoconductor according to image information, and a developer carried on the surface of the photoconductor. A charging means and a developer carrying means, which are composed of the same member, and uniformly coat the surface of the photoconductor with the developer while charging the photoconductor. Is carried, the photosensitive body, after carrying the developer, is selectively exposed according to image information by the exposing means, the developer on the photosensitive body according to the exposure result, By the transfer means It is intended to be transferred selectively recording medium.

In the above-mentioned image forming apparatus, when a voltage is applied to the charging means and the developer carrying means and pressed against the photoconductor, discharge in a minute gap near the contact portion with the photoconductor and charge injection in the contact portion. Thus, the surface of the photoconductor is charged to a uniform potential, and at the same time, the toner is attached to the photoconductor.
The photoconductor, which is charged to a uniform potential and has toner adhered to the surface, is exposed according to image information by the exposing means to obtain an electrostatic latent image. After that, the toner on the photoconductor is selectively transferred to a transfer paper, an intermediate transfer body, or the like.

Further, in the above-mentioned image forming apparatus, since the charging means for charging the surface of the photoconductor to a uniform potential and the developer carrying body carrying the developer and adhering to the photoconductor are constituted by the same member, It is not necessary to separately arrange the scorotron, the developing roller and the like, and the image forming apparatus can be provided with a simple configuration.

According to another aspect of the image forming apparatus of the present invention, the members constituting the charging means and the developer carrying means are elastic members provided so as to come into pressure contact with the photosensitive member. According to the image forming apparatus, since the elastic member is provided so as to be in pressure contact with the photoconductor, the developer is charged by friction with the photoconductor at the pressure contact portion of the elastic member, and the charge necessary for development is obtained. At the same time, it can be attached to the surface of the charged photoreceptor.

An image forming apparatus according to a third aspect of the present invention is provided with voltage applying means for applying a predetermined voltage to the members constituting the charging means and the developer carrying means. According to the above-mentioned image forming apparatus, the member constituting the charging means and the developer carrying means is provided with the voltage applying means for applying a predetermined voltage, thereby charging the surface of the photoconductor to a uniform potential. It is possible to adjust the amount of toner adhered to the surface of the photoconductor.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an image forming unit of a laser printer to which the present invention is applied. In addition,
In this embodiment, a laser printer will be described as an example, but the same image forming apparatus as in this embodiment can be used for other image forming apparatuses such as a copying machine and a facsimile machine.

The laser printer comprises a photosensitive drum 10 as an image bearing member, and a process blade 11 for charging the surface of the photosensitive drum 10 to a uniform electric potential and adhering toner as a developer to the photosensitive drum 10. . The toner layer is formed on the surface of the photosensitive drum 10 downstream of the process blade 11.

In the laser printer, a toner tank 12 for storing toner and the process blade 11 for storing the toner are provided.
Agitator 13 that conveys to the surface of photosensitive drum 10 by
Are provided. As will be described later, the toner is triboelectrically charged in a region where the process blade 11 presses the surface of the photosensitive drum 10, and adheres to the surface 10 of the photosensitive drum.

Further, the laser printer of this embodiment is provided with the scanner unit 14 for selectively irradiating the photosensitive drum 10 on which the toner layer is formed with the laser beam in accordance with the image data inputted from the outside. In the portion of the surface irradiated with the laser beam, the charge charged by the process blade 11 is discharged, and an electrostatic latent image is formed under the toner layer.

Further, the photosensitive drum 10 comes into contact with a toner image transfer roller (hereinafter referred to as "transfer roller") 15 at the downstream side in the rotational direction with respect to the contact position with the process blade 11. Since a bias is applied to the transfer roller 15 by the DC power source 19, when the transfer paper 16 as a recording medium is transferred between the photosensitive drum 10 and the transfer roller 15 by the transfer mechanism (not shown). The toner attached to the photoconductor drum 10 is selectively transferred onto the transfer paper according to the image information, and a toner image is formed. In the image forming apparatus of this embodiment, the charging polarity of toner is the same as the charging polarity of the photosensitive drum 10.

The process blade 11 is constructed by attaching a rubber 11b to a conductive metal plate 11a. The process blade 11 is fixed to a housing (not shown) of the laser printer via a fixing portion 17 so that the rubber 11b presses the photosensitive drum 10, and a voltage is applied to the metal plate 11a by a DC power source 18 from the housing. It The material of the rubber 11b is a material on the triboelectric charging series in which the charging polarity of the toner is negative. The surface of the rubber 11b is configured to have a higher friction coefficient than the surface of the photosensitive drum 10, and the toner is charged by the friction and adheres to the surface of the photosensitive drum 10.

Next, the operation of the laser printer thus configured will be described. A DC power supply 18 is connected to the process blade 11 and a bias is applied. The surface of the photosensitive drum 10 is charged to a uniform potential by discharge in a minute gap near the contact portion between the process blade 11 to which the bias is applied and the photosensitive drum 10 and charge injection in the contact portion. The toner stored in the toner tank 12 is conveyed to the gap formed by the process blade 11 and the photosensitive drum 10 by the rotation of the agitator 13. The conveyed toner is transferred to the process blade 1 by the rotation of the photosensitive drum 10.
1 moves toward the edge of No. 1 and is stopped and retained by the protruding portion 11c of the process blade edge. In this embodiment, the portion 1 protruding from the end of the process blade 11
1c is provided, but the photosensitive drum 1 of the process blade 11
Depending on the pressing force with respect to 0, it is also possible to use a process blade having a structure with no protrusion on the edge.

The accumulated toner is charged by friction on the surface of the photosensitive drum 10 which moves while rotating, and obtains an electric charge necessary for development. Further, the toner is frictionally charged by contact with the surface of the process blade 11 and the surface of the photosensitive drum 10 even while moving in the gap between the process blade 11 and the photosensitive drum 10.

A bias is applied to the process blade 11, the polarity of the bias is the same as the charging polarity of the toner, and the absolute value of the voltage is used as a charging means in the conventional developing device as in the scorotron. The voltage is set to about 1500 V, which is equivalent to the bias applied to the brush charger. In this case, the absolute value of the surface potential of the photosensitive drum 10 is 100
It will be about 0V.

The charged toner on the process blade 11 adheres to the photosensitive drum 10 due to the electric field formed between the process blade 11 and the photosensitive drum 10, and the charged toner on the downstream side of the process blade 11 on the photosensitive drum 10. A toner layer is formed. Next, the surface of the photosensitive drum 10 is
The scanner unit 14 irradiates a laser beam from above the toner layer and exposes it according to image information. At the portion of the photosensitive drum 10 irradiated with the laser beam, the charge charged by the process blade 11 is discharged, and an electrostatic latent image is formed under the toner layer. The absolute value of the surface potential of the exposed photosensitive drum 10 is about 100V.

The surface of the photosensitive drum 10 on which the electrostatic latent image is formed advances to the transfer position and contacts the transfer roller 15 via the transfer paper 16. Although a bias is applied to the transfer roller 15, the bias causes an electric field formed between the transfer roller 15 and the electrostatic latent image formed on the photoconductor 10 to expose the charged toner. It is set so that the exposed portion acts as an attractive force in the direction of the photosensitive drum 10 and the unexposed portion acts as a repulsive force. That is, the DC power supply 19
The voltage applied by is set to 500V. Therefore,
Only the toner of the exposed portion on the photosensitive drum 10 moves to the transfer paper 16 which has passed the transfer position, and the photosensitive drum 1
The image formed as the electrostatic latent image on the transfer sheet 0 is formed as the toner image on the transfer paper 16.

The present invention is not limited to the above embodiment, and can be implemented in various modes without departing from the gist of the present invention. For example, the process blade 11 includes a rubber plate 1a and a rubber plate 1a as in the present embodiment.
It is not limited to the one having 1b attached thereto, and may be made of a metal plate coated with an insulator such as polyimide, or a semiconductive elastic body in which carbon or the like is dispersed in rubber.

Further, in the present embodiment, the toner on the photosensitive drum 10 is directly transferred onto the transfer paper 16, but it can be applied to a system using an intermediate transfer body. Further, although the DC bias method is applied as the bias applied to the process blade 11, a developing method in which an AC voltage is applied can also be applied.

[0024]

As described above, according to the image forming apparatus of the first aspect, the charging means for charging the surface of the photoconductor to a uniform potential and the developer carrying means for carrying the developer and adhering it to the photoconductor. Since the body is composed of the same member, the scorotron,
Since it is not necessary to separately arrange the developing roller and the like, it is possible to provide the image forming apparatus with a simple configuration, and it is possible to reduce the size and cost of the image forming apparatus.

According to the image forming apparatus of claim 2,
Since the members constituting the charging means and the developer carrying means are elastic members provided so as to be in pressure contact with the photoreceptor,
The developer is charged by friction with the photosensitive member at the pressure contact portion of the elastic member to obtain an electric charge necessary for development, and at the same time, can be attached to the surface of the charged photosensitive member, thus providing an image forming apparatus with a simple configuration. it can.

Further, according to the image forming apparatus of claim 3,
Since the voltage applying means for applying a predetermined voltage is provided to the members constituting the charging means and the developer carrying means, the surface of the photoconductor can be charged to a uniform potential, and the surface of the photoconductor can be charged. The amount of adhered toner can be adjusted.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an image forming apparatus that is an embodiment of the present invention.

FIG. 2 is a schematic view of a process blade of the image forming apparatus.

[Explanation of symbols]

 10 Photosensitive Drum 11 Process Blade 12 Toner Tank 13 Agitator 14 Scanner Unit 15 Transfer Roller 16 Transfer Paper 17 Fixed Part 18 DC Power Supply 19 DC Power Supply

Claims (3)

[Claims] 1. A photoconductor on which an electrostatic latent image is formed according to image information, a charging unit for charging the surface of the photoconductor to a predetermined potential, and a developer carrying device for carrying a developer on the surface of the photoconductor. In the image forming apparatus, a charging unit, an exposing unit that exposes the surface of the photoconductor according to image information, and a transferring unit that transfers the developer carried on the surface of the photoconductor to a recording medium. The developer carrying means is composed of the same member and uniformly carries the developer on the surface of the photoconductor while charging the photoconductor, and the photoconductor carries the developer. After that, the exposure means selectively exposes the developer according to the image information, and the developer on the photoreceptor is selectively transferred onto the recording medium by the transfer means according to the exposure result. An image forming apparatus comprising. 2. The image forming apparatus according to claim 1, wherein the member forming the charging unit and the developer carrying unit is an elastic member provided so as to come into pressure contact with the photosensitive member. 3. The image forming apparatus according to claim 1, further comprising a voltage applying unit for applying a predetermined voltage to a member forming the charging unit and the developer carrying unit.