JPS6197676A - Electrostatic latent image developing device - Google Patents

Abstract

PURPOSE:To collect and remove toner charged in the opposite polarity before reaching a developing position, by providing a roller for collecting a developing agent charged in the opposite polarity between a developing agent layer thickness controlling member and the developing position and applying a bias voltage across the roller. CONSTITUTION:An opposite-polarity toner collecting roller 12 is provided between a magnetic blade 11 which controls the thickness of a toner 5 layer o a developing sleeve 10 and a developing position 1a. The gap d1 between the sleeve 10 and roller 12 is set smaller than the thickness of the toner layer on the sleeve 10 and a voltage of the same polarity as the regular toner has is applied across the roller 12 by means of a power source 16. Therefore, toner charged in the opposite polarity and mixed in the toner layer is attracted and removed by means of the collecting roller 12 and, as a result, ground fogging caused by the opposite-polarity toner can be prevented and the picture quality can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Object of the Invention [Field of Industrial Application] The present invention relates to an electrostatic latent image developing device, particularly a dry one-component developing device.

[Conventional technology]

The above-mentioned dry type one-component developing device is widely used because it has advantages such as less variation in image intensity compared to a two-component developing device, no need for density adjustment, and miniaturization of the device.

(Problems to be Solved by the Invention) However, in the one-component developing device, since the developer (toner) is charged only by F!L friction charging with the developing sleeve,
This has the disadvantage that toner tends to have unstable charging polarity. That is, the toner conveyed along the sleeve comes into contact not only with the sleeve but also with other toners. Toner that comes into contact with the sleeve is charged to the desired polarity, but when toners come into contact with each other, if there are toners with uneven characteristics,
One is positively charged and the other is negatively charged. Most of the toner of opposite polarity is regulated by the blade facing the developing sleeve and is not conveyed to the developing position, but some of it is sent to the developing position and adheres to the background portion of the image, causing blurring.

Therefore, it is necessary to eliminate toner having uneven characteristics before it reaches the development position, and an object of the present invention is to solve this problem.

B. Structure of the Invention [Means for Solving the Problems] In a dry one-component developing device, a regulating member for regulating the thickness of the developer on a developing sleeve that holds and conveys the developer and a developing position are provided. , an electrostatic latent image developing device characterized in that a collection roller is provided for adsorbing and collecting developer charged to the opposite polarity, and a bias voltage having the same polarity as that of regular toner is applied to the collection roller.

[For production]

The oppositely charged toner mixed in the toner conveyed to the developing sleeve in a regulated layer thickness is collected and removed by a collecting roller before reaching the developing position.

〔Example〕

The present invention is implemented in, for example, an electrophotographic device, a device for developing an electrostatic latent image formed by a multi-stylus, and other electrostatic latent image developing devices. show.

FIG. 3 schematically shows an example of an electrophotographic apparatus to which the present invention is applied, in which 1 is a photosensitive drum, 2 is a charger, 3 is an image exposure device, 4 is a developing device, and 5 is a developer.

6 is a transfer charger, 7 is a transfer material, and 8 is a cleaning device.

The photoreceptor 1 is uniformly charged by a charger 2, and then subjected to image exposure by an image exposure device 3 to form an electrostatic latent image corresponding to one image. This latent image is developed by a developing device 4 containing a developer 5, and then transferred onto a transfer material 7 by a transfer charger 6 to obtain a hard copy. The residual toner remaining on the photoreceptor is cleaned by a cleaning device 8.

FIG. 4 shows an outline of the one-component developing device that is the subject of the present invention. With the magnet roll 9 fixed, the non-magnetic sleeve 10 is moved in the forward direction (that is, in the same direction in the vicinity) of the photoreceptor l as indicated by the arrow. ), the toner 5 moves in the same direction as the rotation of the sleeve, and after the thickness of the toner adhering to the sleeve is regulated by the magnetic blade 11, it is conveyed to the developing position 1a facing the photoreceptor l. . Since a bias voltage is applied between the drum 1 and the sleeve 10 by the developing bias device 17, the toner 5 adheres to the electrostatic latent image on the photoreceptor according to the latent image potential and development is performed. The toner 5 mainly consists of magnetite and resin components and is magnetic.

The present invention can be implemented in such a dry type one-component developing device.

As shown in FIG. 1, a magnetic blade 11 that regulates the layer thickness of toner 5 on a developing sleeve 10, and a developing device! ! 11
A roller 12 for collecting toner of opposite polarity is provided between the developing sleeve 10 and the developing sleeve 10, and is rotated in synchronization with the developing sleeve 10 in the forward direction. Then, a bias having the same polarity as the regular toner is applied to the collecting row 912 from the power source 16.

Now the gap d between the developing sleeve lO and the collection roller 12
, is made smaller than the thickness of the toner layer formed on the sleeve, the collection roller 12 is brought into contact with the toner layer, and the bias voltage is set to several hundreds of ports. is attracted to the collection roller 12.

Therefore, the toner charged to the opposite polarity, which causes smearing, is attracted and collected before reaching the developing section 1a, thereby achieving the above-mentioned purpose. Note that the adsorbed toner is removed by the scraper 13.
It is scraped off and collected in the container 14.

In the above embodiment, when the toner passes through the gap d1, pressure is applied to the toner by the collection roller 12, which may disturb the layer of toner on the sleeve or cause the toner to fuse onto the sleeve.

FIG. 2 shows an example in which such measures have been taken.

That is, the gear between the collecting roller 12 and the developing sleeve IO,
d2 is several tens to more than the thickness of the toner layer on the sleeve.
Hundreds #1. m is set large to maintain non-contact between the toner layer and the collection roller. Further, a bias in which a direct current is superimposed on an alternating current is applied from a power source 15.

With such a configuration, when a single layer of toner whose layer thickness is regulated by the blade 11 faces the collection roller 12, it repeatedly flies to the collection roller 12 and returns to the sleeve IO due to the AC bias. , because a DC bias of the same polarity as the regular toner tripo is superimposed, so that ultimately only the oppositely charged toner adheres to the collection roller and is removed.

By carrying out so-called jumping collection in this manner, the above-mentioned concerns of the embodiment of FIG. 1 are resolved.

C1 Effect of the invention In a dry type one-component developing device, toner charged to the opposite polarity mixed in the toner that is conveyed to the developing position by the developing sleeve in a regulated layer thickness is adsorbed to the collecting roller in front of the developing position. By collecting and removing the toner, it is effective to prevent blurring caused by toner of opposite polarity and improve image quality.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of the electrostatic latent image developing device of the present invention, FIG. 2 is the same view of another embodiment, and FIG. 3 is a schematic diagram of the electrophotographic device.
FIG. 4 is a schematic diagram of a one-component developing device. DESCRIPTION OF SYMBOLS 1... Photoreceptor, 4... -component developer, 5... Toner, 10... Non-magnetic developing sleeve, 11... Magnetic blade, 1a... Developing section, 12... Reverse Polar toner collection roller, 13...Scraper, 16/17...Bias electric IX&

Claims (1)

[Claims] (1) In a dry type one-component developing device, a member that regulates the thickness of the developer on the developing sleeve that holds and transports the developer and the developing position attracts and traps the developer charged with the opposite polarity. An electrostatic latent image developing device comprising: a collecting roller for collecting toner; and applying a bias voltage of the same polarity as that of regular toner to the collecting roller.