JPH0313974A - Electrophotographic developing device - Google Patents

Abstract

PURPOSE:To reduce the wear of a belt and to eliminate the influence of temperature and humidity by electrifying the inner surface of a developing sheet belt opposite to the polarity of toner, electrostatically adsorbing the toner to the outer surface and carrying toner according to the electrostatic latent image on a photosensitive body. CONSTITUTION:The inner surface of the developing sheet belt 1 is electrified opposite to the polarity of the toner T by an electrifying electrode 3, and in an electrified room 4, the toner T is electrostatically absorbed on the outer surface and carried to the outer part through a forming blade 7. Then, when the charge of the inner surface of the belt 1 is weakened by a negatively electrifying electrode 8 and carried to the position of a hollow (g), the toner T of the outer surface of the belt 1 is attracted to a photosensitive drum 10 by a developing bias voltage E. Additionally, according to the electrostatic latent image of the drum 10, the toner T is transferred to develop the latent image. Therefore, the wear caused by friction of the developing sheet belt is decreased to control the applied voltage to the electrode so that the quantity of electrified charge can be uniformed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrophotographic developing device, and in particular, to a developing device for electrophotography, which develops an electrostatic latent image by transferring a non-magnetic one-component toner to a photoreceptor using static electricity. The present invention relates to the structure of an electrophotographic developing device that performs the following steps.

[Conventional technology]

Conventionally, in electrophotographic developing devices that use non-magnetic one-component toner (hereinafter simply referred to as toner), mechanical w! Generally, a method is adopted in which a developing body such as a developing roller or a developing seat belt and toner are charged with opposite polarities by frictional charging to electrostatically form a toner layer on the surface of the developing body. Mechanical triboelectrification methods for developing bodies include:
A friction material such as a fur brush, roller, or sheet made of an insulating dielectric material is used to directly slide a developing body on which an insulating dielectric layer, etc. is formed, to generate triboelectric charges on the surface of the developing body. There is.

For example, as shown in FIG. 2, in a conventional electrophotographic developing device, a fur brush 22 is rotatably disposed so that its tip comes into contact with the surface of the developing roller 21. At the same time, the fur brush 22 also rotates and generates a band of charge on the developing roller 21 due to friction, which has a polarity opposite to that of the toner T. In FIG. 2, reference numeral 23 indicates a forming blade that makes the thickness of the toner layer on the developing roller 21 uniform, 24 indicates a photosensitive drum consisting of a conductive cylindrical body 24a and a photosemiconductor layer 24b, and 25 indicates a backflow of toner T. In addition, E indicates the developing bias voltage applied between the developing roller 21 and the photosensitive drum 24.

[Problem to be solved by the invention]

In the conventional electrophotographic developing device described above, a mechanical frictional charging method was adopted as the charging method for the developing body.
There were the following problems.

(1) In order to generate the necessary amount of electrical charge, relatively high-speed relative sliding motion between the developing body and the friction body is required, which causes mutual wear and makes it difficult to ensure a long service life.

(2) It is difficult to theoretically predict the amount of mechanical triboelectric charges generated, and electrophotographic developing devices have had to be designed by trial and error.

(3) Frictional charging is greatly affected by environmental changes such as temperature and humidity, and it is difficult to control changes in the amount of charged charge.

In view of the above-mentioned points, it is an object of the present invention to arrange a charging electrode to face the inner surface of a developing seat belt that is arranged to be transportable, and to apply a necessary electrical charge to the inner surface of the developing seat belt by the charging electrode. An object of the present invention is to provide an electrophotographic developing device.

[Means to solve the problem]

The electrophotographic developing device of the present invention is an electrophotographic developing device that develops an electrostatic latent image by transferring non-magnetic one-component toner to a photoreceptor, and is arranged so that it can be transferred by a roller or the like, An endless developing seat belt made of an insulating dielectric material, with a part facing the photoreceptor through a gap and the other part of the outer surface facing the toner charging chamber, and the developing seat belt facing the inner surface of the developing seat belt. and a charging electrode that charges the inner surface of the developing seat belt to a polarity opposite to that of the toner.

[Effect]

In the electrophotographic developing device of the present invention, the developing seat belt whose inner surface is charged by the charging electrode enters the toner charging chamber and electrostatically attracts the toner charged to the opposite polarity to the outer surface. It is possible to transport the toner close to the photoreceptor and transfer the toner to the photoreceptor in accordance with the electrostatic latent image formed on the photoreceptor.

〔Example〕

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a cross-sectional view showing the configuration of an electrophotographic developing device according to an embodiment of the present invention. A developing seat belt 1, a first roller 2a having conductivity and rotatably disposed facing the photosensitive drum 10, and a 20th roller 2a facing the toner charging chamber 4 and rotatably disposed.
b, and a first to charge the inner surface of the developing seat belt l.
Developing seat belt between 0-ra 2a and 20-ra 2b)
1, a toner charging chamber 4 in which toner T made of an insulating dielectric is stored and charged; A stirring paddle 5 is provided in the charging chamber 4 and charges the toner T by friction, and a toner cartridge (
an injection port 6 for injecting the toner T into the toner charging chamber 4 from (not shown); a forming blade 7 for forming the toner T electrostatically attracted to the outer surface of the developing seat belt 1 into a thin layer; In order to reduce the amount of electrical charge on the inner surface of the developing seat belt 1, the inner surface of the developing seat belt 1 on the upper side (as viewed in FIG. The main parts thereof include a reverse charging electrode 8 and a backflow prevention blade 9 that prevents the toner T from flowing back inside the toner charging chamber 4 . In FIG. 1, reference numeral 10 indicates a photosensitive drum 10 consisting of a conductive cylindrical body 10a and an optical semiconductor layer 10b formed on the surface thereof.

The developing seat belt 1 has a 10th-ra 2a and a 20th-ra
The 10th
- The upper side is directed from the toner charging chamber 4 side to the photosensitive drum 10 side, and the lower side is directed from the photosensitive drum 10 side to the toner charging chamber 4 side according to the rotational drive of the -ra 2a (or the 20th -ra 2b) in the direction of the arrow. It is designed to be transported. Further, the developing seat belt 1 is placed at the left end position of the 10th line 2a (
It faces the photosensitive drum 10 via the gap g at the right end position of the 20th-ra 2b (as seen in FIG. 1).
It is exposed inside the toner charging chamber 4.

The charging electrode 3 generates a charged charge having a polarity opposite to the polarity of the charged charge generated on the toner T due to friction when the stirring paddle 5 stirs the toner T in the toner charging chamber 4 .

The passing electrode 8 generates a charge having the same polarity as the charge generated on the toner T by friction when the stirring paddle 5 stirs the toner T in the toner charging chamber 4 .

Note that a developing bias voltage E is applied between the 10th roller 2a and the photosensitive drum IO in order to attract and transfer the toner T attached to the outer surface of the developing seat belt 1 to the photosensitive drum 10. .

Next, the operation of the electrophotographic developing device of this embodiment configured as described above will be explained.

The developing seat belt 1 is attached to the 10th-ra 2a (or
- The toner T is transferred at a constant speed by the rotational drive in the direction of the arrow 2b), and during the transfer from the photosensitive drum IO side to the toner charging chamber 4 side, the inner surface is charged by the charging electrode 3, which is opposite to the charging polarity of the toner T. charged to the polarity of

The developer sorting belt 1 whose inner surface is charged with a polarity opposite to that of the toner T enters the toner charging chamber 4 in which the toner T is stored, and its outer surface is charged by friction caused by stirring by the stirring paddle 5. The toner T is electrostatically attracted to the toner T.

The toner T that is electrostatically attracted to the outer surface of the developing seat belt 1 due to the electrical charge on the inner surface of the developing seat belt 1 is elastically pressed into two to three thin layers as the developing seat belt 1 is transported. The toner is conveyed from inside the toner charging chamber 4 to the outside while being molded by the molding blade 7 that generates force.

Then, during the transfer from the toner charging chamber 4 side to the photosensitive drum 10 side, the charged charge on the inner surface of the developing seat belt 1 is changed by the reverse charging electrode 8 so that the toner T is easily attracted to the surface of the photosensitive drum 10. is lowered.

The toner T, which has been conveyed to the position of the gap g facing the photosensitive drum 10 as the developing seat belt 1 is transported, is transferred to the static image formed on the photosensitive drum 10 by the light beam irradiated onto the surface of the photosensitive drum 1α according to the information. According to the electrostatic latent image, the toner T is selectively attracted and transferred to the place to be attracted by the developing bias voltage E applied between the 10th roller 2a and the photosensitive drum 10, and the toner T is selectively attracted and transferred to the place on the photosensitive drum 10. Develop the electrostatic latent image.

The toner T transferred to the surface of the photosensitive drum 10 is transferred from the photosensitive drum 10 to the surface of a recording medium such as paper, and then fixed on the recording medium by a fixing device, as in the case of normal electrophotography. Ru.

Incidentally, in the above embodiment, a case has been described in which a conductive charging electrode 8i8 is provided in order to reduce the charging charge applied to the inner surface of the developing seat belt 1 by the charging electrode 3, but it is not always necessary to provide the reverse charging electrode 8. do not have.

Further, although a case has been described in which the toner T is charged by friction by stirring with the stirring paddle 5, the method of charging the toner T is not limited to a method using frictional charging.

〔Effect of the invention〕

As explained above, according to the present invention, the following effects can be achieved by applying a charge to the inner surface of the developing seat belt using a charging electrode whose potential can be controlled.

Since the developing seat belt is charged with a non-contact charge, there is no risk of wear of the developing seat belt, etc.
The life of the electrophotographic developing device can be extended.

(2) The amount of electrical charge generated can be easily predicted theoretically, and a trial is being carried out to design an electrophotographic developing device! can be done without making mistakes.

(31i44 degrees, fluctuations in the amount of charged charge due to environmental changes such as humidity can be offset by controlling the voltage applied to the charging electrode, and the amount of charged charge can be easily maintained at a uniform and optimal state at all times. .

[Brief explanation of the drawing]

FIG. 1 is a linear cross-sectional view showing the configuration of an electrophotographic developing device according to an embodiment of the present invention, and FIG. 2 is a linear cross-sectional view showing an example of a conventional electrophotographic developing device. In the figure, l: Developing seat belt, 2a: 10th la, 2b: 20th la, 3: Charging electrode, 4: Toner charging chamber, 5: Stirring paddle, 6... Inlet, 7... Molding blade, 8... Reversely charged electrode, 9... Backflow prevention blade, 10... Photosensitive drum, 10a - Conductive cylinder, 10b - Photosemiconductor layer, g ...Void, T...Toner.

Claims (1)

[Claims] In an electrophotographic developing device that develops an electrostatic latent image by transferring a non-magnetic one-component toner to a photoreceptor, the toner is disposed so as to be transferable by a roller or the like, and a part of the outer surface is formed with a gap. an endless developing seat belt made of an insulating dielectric material and facing the photoreceptor through the belt and having the other part of its outer surface facing the toner charging chamber; and the developing sheet disposed opposite to the inner surface of the developing seat belt. An electrophotographic developing device comprising a charging electrode that charges the inner surface of the belt to a polarity opposite to that of the toner.