JPH0962091A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize developing by toner with a simple constitution, by performing the toner transport to the developing area, toriboelectrification of the toner and the development, with use of an elastic member fixed so as to slide while press-contact is held on an image carrier. SOLUTION: The toner 20 contained in the toner tank 13 is transported to a gap formed between a developing blade 14 and a photoreceptor drum 10 by rotation of an agitator 15. The transported toner 20 is moved in the edge direction of the developing blade 14 by rotation of the photoreceptor drum 10, and dammed while retained by a projecting part of the developing blade edge. Now, the retained toner 20 is rubbed with the photoreceptor drum 10 surface moving by the rotation and to obtain electric charge required for developing by the toriboelectrification. Moreover, the toner 20 is toriboelectrified while held in contact with the developing blade 14 and photoreceptor drum 10 surface even during the time of being moved through the gap between the developing blade 14 and the photoreceptor drum 10. Then, developing bias is impressed to the developing blade 14 by DC power source 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in an electrophotographic recording device, and more particularly to a developing device effective when non-magnetic one-component toner is used as a developer.

[0002]

2. Description of the Related Art Generally, in a developing device which uses a non-magnetic one-component toner as a developer, a toner is attached to a latent image formed on an image bearing member according to image information so as to develop the latent image by attaching the charged toner to the latent image. The frictional charging means for applying electric charge to the developing means and the developing means for adhering the toner to the image bearing member are separately constituted. An elastic roller (hereinafter referred to as a developing roller) or the like is used as the developing means, and toner is attached to the roller surface and conveyed to the developing area. A predetermined voltage (hereinafter referred to as a developing bias) is applied to the developing roller to attach toner to the latent image formed on the image carrier, and the toner is developed. Further, another roller (hereinafter referred to as a supply roller) is used to convey and adhere toner to the developing roller, and the supply roller rotates while contacting the developing roller to adjust the amount of toner adhered to the developing roller. A bias was also applied to.

An elastic blade (hereinafter referred to as a charging blade) is used as the frictional charging means, and the toner is adhered to the surface and pressed against a rotating developing roller to rub the toner moving between the developing roller and the charging blade. It was charged.

[0004]

However, in the developing device adopting the above-described developing method, it is necessary to dispose the developing roller, the supply roller, the charging blade, etc. in the developing device in addition to the image carrier. The developing device itself has a complicated structure, which has been an obstacle to downsizing and cost reduction of the apparatus.

Further, recently, the performance of the toner itself has been improved. By improving the fluidity and the charging property of the toner, the toner is conveyed to the developing area by the supply roller and the developing roller, and the toner is charged by the charging blade. It is conceivable that the triboelectric charging of No. 1 is not always necessary.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a developing device which can realize development with a developer with a simple structure.

[0007]

To achieve this object, in a developing device according to a first aspect of the present invention, the developer is charged by friction with the image carrier at the pressure contact portion of the developing mechanism composed of an elastic member. , After the charge necessary for development is obtained, the further charged developer adheres to the electrostatic latent image formed on the image carrier to perform development, and therefore, the frictional charging means for charging the developer and the image Since the developing member that attaches the developer to the electrostatic latent image formed on the carrier to form the image by the developer is performed by the same member, a developing roller, a supply roller, a charging blade, etc. are not required, and the structure is simple. It becomes possible to configure a developing device.

Further, in the developing device according to the second aspect of the invention, the elastic member has a structure in which an insulating layer is provided on a conductive elastic plate, so that the electric field in the developing region is stabilized and the development is surely performed. In addition, it is possible to prevent abnormal discharge in the developing area.

Further, in the developing device according to the third aspect of the present invention, since the insulating layer has the protruding portion at a position where it is brought into pressure contact with and slides on the image bearing member, the toner is retained in the developing region to ensure triboelectric charging. It will be possible to do.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing a laser printer using the developing device of the embodiment. In this embodiment, a laser printer will be described as an example, but the same developing device as in this embodiment can be used for other image forming apparatuses such as a copying machine and a facsimile machine.

The laser printer includes a photosensitive drum 10 as an image carrier, a corona discharger 11 for charging the surface of the photosensitive drum 10 to a uniform potential, and a laser for the photosensitive drum 10 based on image data input from the outside. The scanner unit 12 which irradiates a beam is provided. Photosensitive drum 1
In the portion of the surface 0 irradiated with the laser beam, the electric charge charged by the corona discharger 11 is discharged, and an electrostatic latent image corresponding to the image data is formed on the surface of the photosensitive drum 10.

In the laser printer, a toner tank 13 for storing a non-magnetic one-component toner (hereinafter simply referred to as toner) 20 as a developer and a toner tank 10 are arranged in the longitudinal direction of the sightseeing drum 10 to expose the toner 20 to light. A developing blade 14 as a developing mechanism that conveys to the surface of the drum 10 and an agitator 15 are provided.

As will be described later, the toner 20 is a region where the developing blade 14 is pressed against the surface of the photosensitive drum 10 and is charged by friction with the surface of the photosensitive drum 10 to be toner on the electrostatic latent image formed on the photosensitive drum 10. 20 is attached.

The photosensitive drum 10 has a developing blade 14
A roller 16 for transferring a toner image (hereinafter referred to as a transfer roller) is contacted on the downstream side of the contact position with the roller, and a bias is applied to the transfer roller 16. For this reason, the photosensitive drum 10 and the transfer roller 1 are transported by a transport mechanism (not shown).
When the recording paper 17 as a recording medium is conveyed between the recording paper 17 and the recording medium 6, the toner 20 attached to the electrostatic latent image is transferred onto the recording paper 17. In a general image forming apparatus, the so-called reversal development method is used, so that the toner 20
Has the same charging polarity as that of the photosensitive drum 10.

The developing blade 14 is constructed by sticking a rubber 14b as an insulating layer to a metal plate 14a as a conductive elastic plate, and a protruding portion 14c formed at the tip of the rubber 14b.
So that it presses against the photosensitive drum 10,
It is fixed to the housing (not shown) of the laser printer via. Further, a voltage is applied to the metal plate 14a by the DC power supply 19. Here, the material of the rubber 14b is a material on the triboelectric charging series in which the charging polarity of the toner 20 is negative. The surface of the rubber 14b has a higher friction coefficient than the surface of the photosensitive drum 10.

Next, the operation of the laser printer thus configured will be described.

Toner 20 stored in the toner tank 13
Is conveyed to a gap formed by the developing blade 14 and the photosensitive drum 10 by the rotation of the agitator 15. The conveyed toner 20 moves toward the edge direction of the developing blade 14 due to the rotation of the photosensitive drum 10, and is stopped and retained by the protruding portion 14c of the developing blade edge. Here, the staying toner 20 rubs against the surface of the photosensitive drum 10 that moves by rotation, and obtains an electric charge required for development by frictional charging. Also,
The toner is frictionally charged by contact with the surface of the developing blade 14 and the surface of the photosensitive drum 10 even while the toner is moving in the gap between the developing blade 14 and the photosensitive drum 10.

Depending on the pressing force of the developing blade 14 against the photosensitive drum 10, a developing blade having no protruding portion 14c at the edge can be used, but the developing blade 14 is provided with the protruding portion 14c at the edge portion. Photosensitive drum 1
This is because the toner 20 is forcibly retained in the portion that is in pressure contact with the 0 surface, and the toner 20 is reliably charged by friction.

A developing bias is applied to the developing blade 14 by a DC power source 19, the polarity of the developing bias is the same as the charging polarity of the toner 20, and the voltage is the absolute value of the potential of the developing blade 14 and is charged. It is set to be lower than the absolute value of the surface potential of the photosensitive drum 10 and higher than the absolute value of the surface potential of the portion discharged by the scanner unit 12. Therefore, the force exerted on the charged toner 20 by the electric field generated between the developing blade 14 and the surface of the photosensitive drum 10 acts as an attractive force on the photosensitive drum 10 in the portion exposed by the scanner unit 12, and in the unexposed portion. To work as a repulsive force.

The developing blade 14 has a metal plate 14a.
Is used, it is possible to keep the portion carrying the toner 20 at the same potential as the output of the DC power supply 19,
A stable electric field can be formed in the development area. In particular, at the end of the developing blade 14, the gap between the developing blade 14 and the photosensitive drum 10 is narrow, and a strong electric field is formed.
The charged toner 20 has a strong adhesive force. Therefore, the toner 20 attached to the exposed portion of the photosensitive drum 10 is
The toner image is formed on the surface on the downstream side in the rotation direction of the photosensitive drum 10 with respect to the position where the developing blade 14 slips through and the developing blade 14 presses against the photosensitive drum 10, and the development is completed.

Further, the developing blade 14 is connected to the metal plate 14a.
Further, since the rubber 14b is attached, the abnormal discharge can be prevented when the toner 20 does not exist in the developing area or when there is an abnormality such as a pinhole in the photosensitive layer on the surface of the photosensitive drum. .

The present invention is not limited to the above embodiments, and can be implemented in various modes without departing from the gist of the present invention. For example, the developing blade 14 is not limited to the one in which the rubber plate 14b is attached to the metal plate 14 as in the present embodiment, but may be one in which an insulating material such as polyimide is coated on the metal plate or carbon or the like in which rubber is dispersed. You may comprise with a conductive elastic body.

Further, as the developing blade 14, an elastic metal plate may be brought into direct contact with the photosensitive drum 10, or a protrusion may be formed at the tip of the metal plate.

Further, in the above-described embodiment, the DC bias system in which a DC voltage is applied as the developing bias is applied, but a developing system in which an AC voltage is applied can also be applied.

Further, although non-magnetic one-component toner is used as the developing material in the above embodiment, it is also applicable to development using magnetic toner.

[0027]

As is apparent from the above description, in the developing device according to the first aspect of the invention, the toner is conveyed to the developing area, the toner is triboelectrically charged, and the developing is fixed to the image carrier so as to slide in pressure. Since the elastic member is used, development with toner can be realized with a simple structure.

Further, in the developing device according to the second aspect of the invention, since the elastic member has a structure in which the insulating layer is provided on the conductive elastic plate, the electric field in the developing area can be stabilized to surely perform the developing. It is possible to prevent abnormal discharge.

Further, since the developing device according to the third aspect has the projecting portion at the position where the insulating layer is brought into pressure contact with and slides on the image bearing member, the toner is retained in the developing region to surely perform the triboelectric charging. Has the effect that can.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a developing device of the present invention.

FIG. 2 is a schematic configuration diagram of a developing blade of the present invention.

[Explanation of symbols]

 10 Photosensitive Drum 11 Discharger 12 Scanner Unit 14 Developing Blade 16 Transfer Roller 19 DC Power Supply

Claims (3)

[Claims] 1. A developing device comprising: an image carrier on which a latent image is formed according to image information; and a developing mechanism for adhering a developer to the image carrier to develop the image, the developing mechanism comprising: A developing device, which is an elastic member fixed to the image carrier so as to be pressed against and slid on the image carrier. 2. The developing device according to claim 1, wherein the elastic member has a configuration in which an insulating layer is provided on a conductive elastic plate. 3. The developing device according to claim 2, wherein the insulating layer has a protrusion at a position where the insulating layer is brought into pressure contact with and slides on the image carrier.