JPS62103676A - Developing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to copying machines, displays, etc. that apply electrophotography.
The present invention relates to a developing device used in an image forming apparatus such as an electrostatic printer.

2. Description of the Related Art Conventionally, developing methods using dry toner are roughly divided into two types: methods using a two-component developer and methods using a one-component developer.

Since the method using two-component developer uses a mixed developer of carrier IJ'a and toner, a toner concentration control device is required to keep the mixture ratio of toner and carrier constant, and periodic replacement due to carrier deterioration is required. It has the following disadvantages. Therefore, recently, in order to eliminate the above-mentioned drawbacks, a developing method using only a one-component developer without using a carrier has been proposed. This developing method includes, for example, Japanese Patent Application Laid-Open No. 54-43038.
There is one shown in Japanese Patent Application Laid-open No. 56-11096, etc., and the structure thereof is shown in FIGS. 3 and 4.

In FIG. 3, 1 is a developing roller, 2 is a toner, 3 is a hopper, 4 is a blade, and 6 is a photoreceptor.

The developing roller 1 is made of a metal material with an uneven surface, and is supplied with toner 2 from a hopper 3 .

Next, when the developing roller 1 rotates in the direction of the arrow, the toner 2 is charged to a predetermined polarity by the blade 4 in sliding contact with the surface of the developing roller 1 and coated on the surface of the developing roller 1. Next, the charged toner 2 flies when it faces the electrostatic latent image on the photoreceptor and develops the image.

In FIG. 4, 6 is a photoreceptor, 7 is a developing roller made of a conductive urethane material that is in sliding contact with the photoreceptor e, 8 is a conductive fur brush that is in rolling contact with the developing roller 7, and 9 is the fur brush 8 and the developing roller 7. 10 is a voltage divider for adjusting the voltage of the power supply 9, and 11 is a hopper containing toner 12. The toner 12 supplied from the hopper 11 to the fur brush 8 is triboelectrically charged by the fur brush 8, and then electrostatically adhered from the fur brush 8 onto the developing roller 7 by the DC voltage of the power source 9 to be coated. When the toner 12 on the developing roller 7 faces the electrostatic latent image on the photoreceptor 6, it flies and develops.Problems to be Solved by the InventionIn the developing method shown in FIGS. 3 and 4, , there are the following problems.

After one development, the difference between the areas where the toner on the developing roller flies to the image area and the areas where it does not fly is difficult to equalize in the subsequent coating process, and appears as a hysteresis phenomenon during the next development, resulting in ghost development. . Furthermore, if the developing action is continued for a long time in this state, the toner that did not fly onto the developing roller may aggregate, and the adhesion between the toner and the developing roller increases, making it difficult to coat the toner with a uniform thickness. Uneven development occurred.

The present invention solves the conventional problems and provides a developing device with high image quality.

Means for Solving the Problems The present invention provides a hopper having an outlet and containing a developer, a movable body provided at the outlet for carrying the developer, and a movable body disposed within the hopper that contacts or contacts the movable body. A fur brush provided close to the movable body and the fur brush have a gap C between them.
It is equipped with a voltage applying means that superimposes a DC voltage on the voltage.

action The effect of this technical means is as follows.

That is, the developer remaining on the movable body after development is reciprocated by a 5C voltage between the movable body and the fur brush,
This method prevents the developer from clumping, agglomeration of the developer, and high adhesion between the developer and the moving object, and coats the moving object with the developer using a DC voltage superimposed between the moving object and the fur brush. Therefore, high-quality development without ghost development and development unevenness is possible.

Embodiment FIGS. 1 and 2 show a developing device according to an embodiment of the present invention, which is an example used in the developing process of a copying machine.

In FIG. 1, reference numeral 13 denotes a photosensitive drum which is a charge holding member having an electrostatic latent image, and is provided by coating a photosensitive material 16 such as zinc oxide, selenium, OPC, etc. on the surface of a base 14 of a module. It is something.

Reference numeral 16 denotes a charger which applies corona, for example, negative in the case of zinc oxide and positive in the case of selenium, depending on the photosensitive material 16 of the photosensitive drum 13, by a first high-voltage DC power supply 17. 16 is charged over the entire surface. 18 is an optical section that transfers the pattern light image to the photosensitive drum 1.
3 to form a latent image. 19 is an insulating toner which is a developer; 20 is a hopper having an outlet 21 and containing the toner 19; Reference numeral 22 denotes a developing roller which is a moving body, and is a metal roller made of, for example, SUS, A/, etc., with an uneven surface. Further, the developing roller 22 is provided at the outlet 21 and at a position facing the photosensitive drum 13 with a certain gap therebetween, and is rotated, for example, in a counterclockwise direction. Reference numeral 23 denotes a fur brush, which has conductive fiber bristles 25 made of rayon containing carbon, for example, planted on the outer peripheral surface of a mandrel 24.

Further, the fur brush 23 is disposed within the toner 19 of the hopper 2o, slides on the surface of the developing roller 22, and is rotated clockwise, for example. Reference numeral 26 is a second high-voltage power source serving as a voltage applying means, and a voltage is applied between the developing roller 22 and the fur brush 23.
A blade 027 that applies a voltage obtained by superimposing a DC voltage on a C voltage is a regulating member that regulates the further thickness of the toner. , and is provided upstream from the developing section. The blade 27 may be made of an elastic material and provided in sliding contact with the surface of the developing roller 22, as in the case of the blade 272L shown in FIG. A scraping plate 028, which may be provided facing each other with a predetermined gap, is in contact with the bristles 26 of the fur brush 23 to equalize the amount of toner 19 in the bristles 26.

The operation of the developing device of one embodiment constructed as described above will be explained below. In FIGS. A negative corona is applied by the first high-voltage DC power supply 17 to the zero charger 16 to be described, so that the entire surface of the photosensitive drum 13 is negatively charged.

Next, a pattern light image is projected onto the negatively charged photosensitive drum 13 by the optical section 18 to form a latent image. Meanwhile, the toner 19 in the hopper 20 is supplied into the bristles 26 by the rotation of the fur brush 23.

Next, the excess toner 19 in the bristles 26 is scraped off by a scraping plate 28 and an appropriate amount is supplied. Furthermore, fur brush 23
The rotation of the toner 19 transports the toner 19 to a position facing the developing roller 22 . The appropriate amount of supplied toner 19 is removed from the scraping plate 28. Rubbing with the surface of the developing roller 22 and the phage 2
Uniform positive charging is achieved by the stirring action of 230 rotations. Next, a positive DO voltage is superimposed on the MU C voltage on the fur brush 23 side by the second high voltage power supply 26 between the developing roller 22 and the far plastic/23, and the toner 19 is reciprocated and transferred onto the surface of the developing roller 22. Coat the prescribed toner to a thickness greater than one layer. The thickness of the toner layer on the surface of the developing roller 22 at this time may vary within a predetermined toner layer thickness or more. Next, the developing roller 22 rotates, and the toner 19 on the surface of the developing roller 22 is removed by the blade 27 (271
L.

27b), a portion of the toner is scraped off and the toner is regulated to a predetermined thickness. Next, when the negatively charged latent image on the photosensitive drum 13 faces the positively charged toner 19 on the surface of the developing roller 22, the toner 19 flies onto the photosensitive drum 13 and can be developed. Next, the toner 19 remaining on the surface of the developing roller 22 after development is reciprocated by the AC voltage of the second high voltage power supply, and
It is possible to prevent toner aggregation and high adhesion between the toner and the developing roller. Therefore, high-quality development without ghost development and development unevenness is possible. In the present invention, the blade 27 is provided in consideration of density variations and specific resistance variations of the bristles 26 of the fur brush 23, but the bristles 26
5 density variation.

If the specific resistance variation is small, the same effect can be obtained even if the blade 27 is removed.

Effects of the Invention The present invention superimposes a DC voltage on an AC voltage between the developing roller and the fur brush, thereby reducing the history of toner development, aggregation, and high adhesion between the toner and the developing roller after development. can be eliminated. Therefore, a stable groove layer of toner can always be coated on the developing roller, so that stable development with high image quality can be achieved.

[Brief explanation of drawings]

1 and 2 are cross-sectional side views of main parts of a developing device according to an embodiment of the present invention, and FIGS. 3 and 4 are cross-sectional side views of main parts of a conventional developing device using a one-component developer. It is. 13...Charge carrier, 19...Developer, 2o...-hopper, 21...Exit, 2
2...Moving body, 23...Fur brush, 26...Voltage application means.

Claims (1)

[Claims] a charge carrier having an electrostatic latent image; a hopper containing a developer and having an outlet; a moving body disposed at the outlet and facing the charge carrier and carrying the developer; A developing device comprising: a fur brush disposed in a hopper in contact with or close to the movable body; and voltage applying means for superimposing an AC voltage and a DC voltage between the movable body and the fur brush.