JPH04304487A - Developing device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of the scattering of toner and to prolong the life of a toner replenishing member by specifying the electrical resistance of the surface of a conductive fur brush roller as the toner replenishing member. CONSTITUTION:A toner replenishing port 13a is formed on the toner hopper 13 of a developing container 1, and the conductive fur brush roller 12 as the toner replenishing roller 12 is arragned so as to block the toner replenishing port 13a. A voltage applying member 17 is arranged on the lower part of the conductive far brush roller 12 and connected with a constant current power source 18 as a bias applying means. The conductive fur brush roller 12 is composed of a brush whose electrical resistance is 10<2>-10<7>OMEGAcm and a shaft center having higher resistance than that. Thus, the toner on the conductive fur brush roller 12 has the injection of the charge of the same polarity as that of the toner, and sufficiently electrified, so that even if stirring electrification is not sufficient, the scattering of the toner and the soiling of a copied image do not occur. Besides, it is unnecessary that an applied voltage is not made so high, as well, because the electrical resistance of the brush is low.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device installed in a copying machine or the like, and more particularly to a developing device using a developer mixed with carrier powder and toner powder.

0002

[Prior Art] This type of developing device is
There is one disclosed in Japanese Patent No. 1165. In a developing device that uses a developer mixed with carrier powder and toner powder,
It is necessary to maintain the toner concentration in the developer within a predetermined range, and for this reason, when the toner concentration in the developer decreases, a toner replenishing member is provided that replenishes the developer with toner powder.

[0003] In the developing device disclosed in the above publication,
In order to ensure that the replenished toner powder is not separated from the developer and the toner powder immediately adheres to the carrier powder in the developer without increasing the mixing and agitation force, the toner supply member is provided with the developer. a means for forming a circulating flow, a replenishing roller that disperses and holds replenishing toner powder on its surface and contacts this holding surface with the developer circulating flow, and a replenishing roller between the replenishing roller and the developer circulating flow. A bias voltage power supply having the same polarity as the toner powder is provided.

Furthermore, the replenishment roller is constructed such that the surface of the conductive roller is coated with short fibers having an electrical resistance of 108 to 1011 Ω·cm so that the toner powder for replenishment is attached to the surface of the short fibers, and the bias voltage is set to a conductive roller. The structure is such that the voltage is applied directly to the roller. In addition, as a replenishment roller, the conductive roller surface has a resistance of 108 to 1011 Ω・cm.
A material covered with a porous elastic material is used. In this developing device, a voltage of the same polarity as the toner is applied to the short fibers or porous elastic body covered with a conductive roller, and then the toner is dispersed and held in the short fibers covered with the conductive roller. is brought into contact with the developer brush on the developer carrier to replenish the developer with toner.

[0005]

[Problems to be Solved by the Invention] However, in the developing device according to the above-described conventional example, when used for a long period of time, toner sticks to the short fibers of the replenishment roller, and the resistance of the short fibers increases, causing charge to be injected into the toner. Therefore, the toner cannot be properly mixed into the developer, resulting in toner scattering and image staining. Therefore, there is a problem that the life of the replenishment roller is shortened. The present invention has been made by focusing on the above-mentioned conventional problems, and it reduces the resistance of the toner replenishing member, and prevents toner scattering etc. due to increased resistance of the toner replenishing member even if the developer is used for a long period of time. It is an object of the present invention to provide a developing device that does not generate toner and has a long life of a toner replenishing member.

[0006]

[Means for Solving the Problems] The invention according to claim 1 provides a developer container containing a developer containing a mixture of carrier powder and toner powder, and an electrostatic latent image formed on a photoreceptor by the developer in the developer container. a circulating flow forming means for forming a circulating flow of developer; and a toner replenisher that disperses and holds replenishment toner powder to be supplied to the developer and contacts the circulating flow of developer to replenish the toner. and a voltage applying means for applying a voltage to the toner replenishing member such that the toner replenishing member has the same polarity as the replenishing toner powder, the surface of the toner replenishing member has an electric resistance of 102 to 107 Ω·c.
This is a developing device characterized in that it is constructed of a material of m.

[0007]

[Operation] In the invention as claimed in claim 1, since the surface of the toner replenishing member is made of a material having an electrical resistance of 102 to 107 Ω·cm, the resistance of the conductive fur brush increases extremely even if the developing device is used for a long period of time. There is no problem in injecting charge into the toner. Therefore, there is no possibility that the toner cannot be properly mixed into the developer.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. Reference numeral 1 indicates a developer container, and a developer 2 composed of carrier powder made of iron powder or the like and toner powder is stored in the developer container 1. Inside the developer container 1,
Developing sleeves 3, 4, and 5 are provided. A part of the circumferential surface of the developing sleeves 3, 4, and 5 is located at the opening 1 of the developing container 1.
a, and this exposed portion faces the photoreceptor belt 6. The developing sleeves 3, 4, and 5 are designed to rotate clockwise. Magnets 3a, 4a, and 5a are fixedly provided in the developing sleeves 3, 4, and 5, respectively.

A doctor 11 is arranged near the developing sleeve 3, and a developer removing plate 8 is arranged near the developing sleeve 5. Furthermore, the developer storage area 1 of the developer container 1
b is provided with paddles 9 and 10, and these paddles 9 and 1
0 rotates clockwise. The circulating flow forming means includes the developing sleeves 3, 4, 5, the magnets 3a, 4a, 5a, and the doctor 11.
, a developer removing plate 8 and paddles 9 and 10.

Reference numeral 13 designates a toner hopper, and replenishment toner powder 14 is accommodated in the toner hopper 13. In addition, a stirring arm 15 is provided inside the toner hopper 13.
is arranged, and this stirring arm 15 rotates clockwise. Furthermore, an agitator 1 is installed in the toner hopper 13.
6 is provided.

The toner hopper 13 has a toner supply port 1.
3a is formed. Reference numeral 12 indicates a conductive fur brush roller as a toner replenishing member, and this conductive fur brush roller 12 is arranged to close the toner replenishing port 13a. The conductive fur brush roller 12 is composed of a brush 12b having an electrical resistance of 102 to 107 Ω·cm and a shaft center 12a on which the brush 12b is installed. The electrical resistance of the shaft center 12a is set to be lower than that of the brush 12b. Conductive fur brush roller 1
2 rotates clockwise. The shaft center 12a is grounded. Reference numeral 19 indicates a flicker that knocks off the toner held on the conductive fur brush roller 12.

As shown in an enlarged view in FIG. 2, a voltage applying member 17 is disposed below the conductive fur brush roller 12.
It is in contact with 2. The voltage application member 17 is connected to a constant current power supply 18 as a bias application means.

Next, the operation of this developing device will be explained. Paddles 9 and 10 rotate clockwise to supply developer 2 to developing sleeve 3 which rotates clockwise. The developer 2 supplied onto the developing sleeve 3 is supported on the developing sleeve 3 by the magnetic force of the magnet 3a, forming a developer brush. The developer brush on the developing sleeve 3 is regulated at a constant height by the doctor 11.

The developer 2 on the developing sleeve 3 is sequentially sent to the developing sleeve 4 and then to the developing sleeve 5, and a developer brush is placed on the developing sleeve 4 by a magnet 4a, and on the developing sleeve 5 by a developing sleeve 5a. is carried. On the other hand, the photoreceptor belt 6 is driven in the direction indicated by the arrow, and an electrostatic latent image of positive polarity is formed by a device (not shown). After rubbing, negatively charged toner powder is supplied to the electrostatic latent image, and development is performed.

After the development operation, the developer brush on the developer sleeve 5 is removed from the developer sleeve 5 by the developer removal plate 8, and the developer 2 that constituted the developer brush is removed.
falls into the developer storage area 1b. And this developer 2
is stirred and mixed with the developer 2 in the developer storage area 1b by the paddles 9 and 10, and then supplied onto the developing sleeve 3 again.

The stirring arm 15 and agitator 16 in the toner hopper 13 rotate clockwise to smoothly supply replenishing toner powder to the conductive fur brush roller 12 and to prevent toner bridges from occurring. When the toner concentration in the developer 2 falls below a certain level, a means (not shown) will
It is detected. Then, the conductive fur brush roller 12 holding the toner powder dispersedly rotates clockwise.Then, the conductive fur brush roller 12 hits the flicker 19, and the toner on the fur brush roller 12 is knocked off, and the toner powder is transferred to the toner. From the supply port 13a to the developer storage area 1
Supply to b.

The constant current power supply 18 applies a negative voltage to the voltage application member 17, and the voltage is applied to the conductive fur brush 12 via the voltage application member 17. Therefore, charges of the same polarity as the toner are injected into the toner on the conductive fur brush roller 12, and the toner becomes sufficiently charged. Therefore, even if the stirring and charging by the paddles 9 and 10 is insufficient, toner scattering and copy image staining will not occur.

The brush 12b has an electrical resistance of 102 to 10
Since it is 7Ω·cm, the voltage applied by the constant current power supply 18 can also be set relatively low. Furthermore, even if the developing device is used for a long period of time and toner adheres to the brush 12b, the resistance of the brush 12 does not become extremely high, and the applied voltage does not need to be so high.

In the above embodiment, the toner replenishing member is constituted by the conductive fur brush roller 12, but the present invention is not limited thereto, and the toner replenishing member may be constituted by a porous elastic body. Further, the developing device of the present invention can be installed not only in the above-mentioned copying machine but also in facsimile machines and various printers.

[0020]

As described above, according to the present invention, since the surface of the toner replenishing member is made of a material having an electrical resistance of 102 to 107 Ω·cm, the resistance of the toner replenishing member remains constant even when the developing device is used for a long period of time. Toner scattering and the like caused by rising do not occur, and the life of the toner replenishing member can be extended.

Furthermore, as shown in the embodiment, since the constant current power supply 18 is used, the amount of charge supplied from the conductive fur brush roller 12 to the replenishing toner can be kept constant, and the mixing of toner into the developer can be always stabilized. You will be able to do this. Further, since voltage is applied to the conductive fur brush 12 via the fixedly arranged voltage applying member 17, there is no possibility of contact failure.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a developing device according to an embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG. 1;

[Explanation of symbols]

1 Developing container 2　　　　　Developer 3 Developing sleeve 4 Developing sleeve 5 Developing sleeve 6 Photoreceptor belt 3a Magnet 4a Magnet 5a Magnet 9 Paddle 10 Paddle 12 Conductive fur brush roller 12a Axis center 12b Brush 18 Constant current power supply

Claims (1)

[Claims] 1. A developing container containing a developer containing a mixture of carrier powder and toner powder, a developing means for developing an electrostatic latent image on a photoreceptor with the developer in the developing container, and circulation of the developer. a circulating flow forming means for forming a flow; a toner replenishing member that disperses and holds replenishment toner powder to replenish the developer and replenishes the toner by contacting the circulating flow of the developer; and a toner replenishing member that replenishes the toner to the toner replenishing member. In a developing device, the member has a voltage applying means for applying a voltage having the same polarity as the replenishing toner powder, and the surface of the toner replenishing member has an electric resistance of 102.
A developing device characterized in that it is constructed of a material having a resistance of 107Ω·cm to 107Ω·cm.