JPH09230697A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high quality image by forming a thin toner layer stable for a long period of time, and prevent contamination of the inside of a developing device resulting from sputter of a toner. SOLUTION: The thickness of a toner 14 attached to the surface of a developing roller 22 is restricted by a resilient member 30. The toner 14 stagnating or sputtered around the resilient member 30 because of insufficient charging is adsorbed to the surface of the developing roller 22 due to a potential gradient generated between a conductive member 32 and the roller 22. That is, the absolute of a bias voltage impressed on the conductive member 32 is set greater than the absolute of the developing bias voltage to be impressed on the roller 22 so that s potential gradient is generated which causes the toner 14 to transfer to the developing roller 22. Therefor the toner 14 stagnating or sputtered is drawn toward the surface of the roller 22, and a stable thin layer of toner is established.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device, and more particularly to a printer or PPF using an electrophotographic method, for example.
The present invention relates to a developing device for developing an electrostatic latent image formed on the surface of a photoconductor using a one-component developer made of non-magnetic toner.

[0002]

2. Description of the Related Art An example of a conventional developing device of this type is disclosed in Japanese Patent Application Laid-Open No. 60-736 filed on April 25, 1985.
No. 48 (G03G 15/08). In this developing device, the surface of the developer carrying member is provided with irregularities, and the surface (abdominal surface) of the flexible elastic blade excluding the end portion is brought into contact with the developer carrying member. In this case, a uniform thin toner layer is formed.

[0003] Further, Japanese Patent Publication No. 63-15580 (G03G 15/0) filed on April 5, 1988.
In the developing device disclosed in 8), a metal leaf spring and an elastic body located between the metal leaf spring and the developer carrying member are integrally formed, and the surface of the abdomen is pressed against the developer carrying member to develop. A uniform and thin developer layer is formed on the surface of the agent carrier.

[0004]

However, in any of the above-mentioned methods, when the developer is insufficiently charged, the adhesive force between the developer and the developer carrying member is weak, so that the elastic member There is a drawback that the developer stays or scatters after passing through the (developer regulating member). In addition, when used in that state for a long period of time, the developer is filmed on the elastic member (developer regulating member), and vertical stripes are generated in the developer layer formed on the surface of the developer carrying member, resulting in poor image quality. There was also the drawback of deterioration.

Therefore, a main object of the present invention is to provide a developing device capable of forming a stable and uniform developer layer on the surface of a developer carrying member for a long period of time to realize high image quality.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a developer carrier for supplying a developer adhered to the surface thereof to a photoconductor and a developer adhered to the surface of the developer carrier in contact with the developer carrier. In a developing device including a developer regulating member that regulates the thickness of the developer, a conductive member that attaches the developer to the surface of the developer carrying body by a potential difference generated between the developer carrying body and a bias voltage is provided. It is a developing device.

[0007]

The developer regulating member provided in contact with the developer carrying member forms a uniform developer layer having a predetermined thickness on the surface of the developer carrying member. Then, a bias voltage is applied to the conductive member provided on the downstream side in the flow direction of the developer, and the developer that has passed through the developer regulating member and accumulated or scattered is attached (landed) to the developer carrier. That is, a bias voltage is applied to the conductive member so that the developer moves from the conductive member to the developer carrier, and the developer is carried by the potential gradient between the conductive member and the developer carrier. Transfer to the body. Therefore, the developer that has passed through the developer regulating member is attached to the surface of the developer carrier without scattering.

[0008]

According to the present invention, a uniform developer thin layer can be formed on the surface of the developer carrier by providing a potential gradient between the conductive member and the developer carrier. , High image quality can be expected stably over a long period of time.
The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, the developing device 10 of this embodiment.
Includes a photosensitive drum (which may be a photosensitive plate, a photosensitive belt, or the like) 12 which is an electrostatic latent image carrier, and a toner 14 which is a one-component developer is attached to the latent image formed on the surface of the photosensitive drum 12 to make visible. It is to be visualized. The toner 14 is housed in the housing 16, and the toner 14 is supplied to the developing roller 22 as a developer bearing member by the agitator 18 and the supply roller 20 provided in the housing 16. That is, below the housing 16, the developing roller 22 is arranged so as to contact the photosensitive drum 12. Further, the developing device 10 includes a pressing device 24 for pressing the developing roller 22 against the photoconductor 12, and the pressing device 24 presses the housing 16 including the developing roller 22 in the arrow A direction. As shown in FIG. 1, the pressing device 24 is composed of, for example, a metal leaf spring member or a spring coil.

A voltage distributor 26 is connected to the supply roller 20 and the developing roller 22, and a predetermined bias voltage from a power supply device 28 is applied to each of them. Also, housing 1
Reference numeral 6 denotes an elastic member 30 and a conductive member 3 for controlling the thickness of the toner 14 attached to the surface of the developing roller 22.
2 are provided. In addition, around the photosensitive drum 12,
A charging device 34, a cleaning device 36, etc. are arranged.

The elastic member (doctor blade) 30 is made of a synthetic resin such as urethane rubber, and one end (free end) of the elastic member 30 is elastic on the surface of the developing roller 22, as shown in FIG. The other end (fixed end) of the elastic member 30 is fixed to the housing 16 so as to be pressed into contact with.
By the elastic member 30, the toner 14 conveyed to the surface of the developing roller 22 or its periphery by the agitator 18 and the supply roller 20 has a predetermined thickness according to the pressing force of the elastic member 30 against the developing roller 22. Regulated.

Further, as can be seen from FIG. 2, the elastic member 3
On the back surface (upper surface) of 0, a conductive member 32 that regulates the thickness of the toner 14 attached to the surface of the developing roller 22 is provided, and the tip (free end) of the conductive member 32 is the elastic member 3.
The conductive member 32 is fixed to the housing 16 so as to be downstream with respect to the free end of 0 in the flow direction of the toner 14, that is, the rotation direction of the developing roller 22.

The conductive member 32 is made of a metal such as stainless steel or phosphor bronze, and is a leaf spring member having an appropriate elasticity.
The voltage divider 26 is connected and a predetermined bias voltage from the power supply device 28 is applied. The bias voltage applied to the conductive member 32 is set to a value whose absolute value is larger than the absolute value of the developing bias voltage applied to the developing roller 22. Therefore, the toner 14 adhered (landed) to the surface of the developing roller 22 or floating (scattered) near the surface of the developing roller 22 receives a predetermined pressing force by the elastic member 30.
Are attracted by the bias voltage so as to adhere to the surface of the developing roller 22.

That is, the toner 14 conveyed by the supply roller 20 is regulated in thickness by the elastic member 30 so as to have a thin layer, and the toner 14 and the elastic member 30.
A charge is applied to the toner 14 by frictional charging between and. The toner 14 that is insufficiently charged there stays or scatters in the vicinity of the elastic member 30. The toner 14 is applied to the surface of the developing roller 22 by applying a predetermined bias voltage to a conductive member 32 provided so as to project downstream of the elastic member 30 in the flow direction of the toner 14. It is attached so as to be attracted.

Then, the charging device 34 (see FIG. 1) holds a potential on the surface of the photosensitive drum 12, and an electrostatic latent image is formed by an exposing means (not shown). This electrostatic latent image is developed with a thin toner layer uniformly formed on the surface of the developing roller 22 by the elastic member 30 and the conductive member 32. In operation, when a mode for starting development is designated by, for example, key input, the supply roller 20 is driven by a motor (not shown) as shown in FIG.
And the developing roller 22 rotates in the direction of the arrow. Then, the toner 14 is supplied to the developing roller 2 by the supply roller 20.
2 is supplied. Toner 1 supplied to the developing roller 22
4 is electrostatically attracted to the surface of the developing roller 22, and the elastic member 30 and the conductive member 3 are rotated as the developing roller 22 rotates.
2 is conveyed in the direction in which it is arranged.

As described above, the toner 14 has its thickness regulated by the elastic member 30 and is triboelectrically charged. Then, as shown in FIG. 3, the toner 14 accumulated or scattered near the elastic member 30 due to insufficient charging.
Are attracted to the surface of the developing roller 22 by the potential gradient (E) generated between the conductive member 32 and the developing roller 22. Therefore, on the surface of the developing roller 22,
A stable toner thin layer is formed. Then, by applying a predetermined developing bias voltage to the developing roller 22 by the voltage distributor 26 and the power supply device 28, the electrostatic latent image formed on the surface of the photosensitive drum 12 is toner-developed.

As described above, the elastic member 30 for controlling the thickness of the toner 14 attached to the surface of the developing roller 22.
Separately from the (developer regulating member), a conductive member 32 is arranged on the downstream side in the flow direction of the toner 14 and a bias voltage larger than the developing bias voltage applied to the developing roller 22 is applied to the conductive member 32. By applying, the toner 14 accumulated or scattered near the elastic member 30 can be adsorbed (landed) on the surface of the developing roller 22. Therefore, it is possible to prevent the toner scattering or the toner fusion which increases with the lapse of time, and always realize a stable high quality image.

In the above embodiment, the conductive member 32 is used.
An example is shown in which the conductive member 32 is arranged so that the front end (free end) thereof is slightly floated from the surface of the developing roller 22, but instead of such a conductive member 32, as shown in FIG. , The end (free end) of the conductive member 32 to the elastic member 30.
The surface of the abdomen of the conductive member 32 (one main surface) may be pressed into contact with the surface of the developing roller 22. Therefore, the effect of the attraction due to the potential gradient (E) generated between the conductive member 32 and the developing roller 22 and the effect of the pressing force received from the conductive member 32 are combined, and the toner layer that has passed through the elastic member 30 becomes thinner. It will be stable.

Further, referring to FIG. 5, the outer surface of the back surface (upper surface) and the tip (free end) of the elastic member 30 is coated with a conductive material as shown by diagonal lines, and the tip (or back surface) is coated.
By applying a bias voltage to the elastic member 30,
The scattered toner that has passed through is further positively attached to the surface of the developing roller 22. If, for example, a material containing fluorine is used as the conductive member, vertical stripes are generated in the toner thin layer formed on the surface of the developing roller 22 due to toner fusion (filming), resulting in deterioration of the image. Such problems can be solved.

The conductive member 32 is not limited to one made of metal such as stainless steel, but a conductive film (or sheet) such as urethane or polyester may be used, and the elastic member 30 is made of conductive material such as stainless steel. Of course, it may be configured with a flexible member.

[Brief description of drawings]

FIG. 1 is an illustrative view showing one embodiment of the present invention;

FIG. 2 is an illustrative view showing an elastic member and a conductive member in the embodiment of FIG.

FIG. 3 is an illustrative view showing an influence on a toner when a bias voltage is applied to the conductive member of the embodiment of FIG.

FIG. 4 is an illustrative view showing a modified example of the conductive member.

FIG. 5 is an illustrative view showing a modified example of an elastic member.

[Explanation of symbols]

 10 ... Developing device 12 ... Photosensitive drum 14 ... Toner 20 ... Supply roller 22 ... Development roller 26 ... Voltage distributor 28 ... Power supply device 30 ... Elastic member 32 ... Conductive member

Claims (6)

[Claims] 1. A developer carrier for supplying a developer adhered to the surface of a photoreceptor to a photosensitive member, and a thickness of the developer adhered to the surface of the developer carrier in contact with the developer carrier. In the developing device, a developing device is provided with a conductive member that adheres the developer to the surface of the developer carrying member by a potential difference generated between the developer carrying member and the developer carrying member. . 2. The developing device according to claim 1, wherein the absolute value of the bias voltage applied to the conductive member is larger than the absolute value of the developing bias voltage applied to the developer carrying member. 3. The conductive member is arranged downstream of the developer regulating member in the flow direction of the developer.
The developing device according to claim 1. 4. The developing device according to claim 1, wherein the conductive member is arranged such that an end portion of the conductive member is in contact with the developer carrying member. 5. The conductive member is arranged such that one main surface thereof is in contact with the developer carrying member.
The developing device according to any one of the above. 6. The developing device according to claim 1, wherein the developer regulating member itself or its surface has conductivity.