JPS643257B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing device using a developer. In recent years, development methods using one-component developers have been considered superior to conventional two-component development methods in terms of simplicity, durability, image quality, etc.
Intensive development and research is underway.

In particular, development methods using insulating toner are attracting attention because they enable transfer to plain paper using corona discharge. In this method, insulating toner is charged and applied thinly and uniformly onto a toner carrier, and visualization is performed by bringing the toner carrier close to or in contact with a latent image forming member. , conventionally had the following drawbacks.

(1) Components in the toner that are difficult to develop (often fine powder) gradually accumulate on the developing roller, reducing the developing ability.

(2) A uniform toner layer is not formed only by means of applying toner to the developing roller, and a history on the developing roller due to the remaining toner from the previous development appears on the image. In order to avoid such development, it has been devised to scrape off the toner remaining on the developing roller. As an example of this, a uniform roller a and a developing roller b as shown in FIG.
or an elastic plate C as shown in Figure 2 a.
There is a device that scrapes off the toner on the developing roller b. In the example shown in FIG. 1, uniform coating is achieved, but the deterioration in developing ability due to fine powder and the like cannot be avoided. In addition, in the example shown in FIG.
(See Figure 2 b), but when scraping off the toner, the toner application state becomes uneven, probably due to uneven frictional charging when X passes through the window d. Easy to occur. This becomes a defect that appears as uneven shading in the image.

An object of the present invention is to provide a developing device that overcomes the drawbacks of the prior art, does not reduce developing ability, and has no historical development density unevenness in developing performance.

Examples will be described below with reference to the drawings.
In FIG. 3a, 1 is a developing roller (conductive rubber roller), and 2 is an elastic coating member (made of 2 mm thick urethane rubber) that comes into contact with the roller 1. 3 is an elastic scraper (made of 0.2 mm thick phosphor bronze). 4 is a screw 5 that collects the toner scraped off by the elastic scraper 3 toward the longitudinal center of the sleeve.
Hopper 11 removes the toner gathered in the center.
It is a screw that conveys the material to the top of the container. As shown in FIG. 3b, the screw 4 has grooves 4a cut in opposite directions from the center.

With the above structure, the developer remaining on the developing roller 1 is removed by the elastic scraper 3 and then removed from the developing roller 1 by the screw 4.

FIG. 4 shows an example in which magnetic toner is used. 1' is a non-magnetic sleeve containing a magnet roll, 2' is a magnetic blade facing one magnetic pole of the magnet, and 1' and 2' are spaced apart from each other. 3 is the same scraper as in the previous embodiment. The toner scraped off on the magnetic sleeve 1' by the scraper 3 is collected by the magnetic roll 6, and
The material is conveyed upward by magnetic force between magnetic rollers 7 and 6 that rotate at the same speed. Further, reference numeral 10 denotes a canopy that prevents the pressure of the toner inside the hopper from being applied to the conveying path 12 in order to improve the conveying ability.

By adopting the configurations in the above two embodiments,
Deterioration of the developing roller can be prevented, and furthermore, the toner that has been scraped off and has an abnormal charge can be mixed with the toner in the hopper in the area 9 without directly touching the developing roller 1, thereby preventing uneven coating density. It became possible.

[Brief explanation of drawings]

1 and 2 a and b are explanatory diagrams of a conventional developing device, FIG. 3 a is a sectional view of one embodiment of the present invention, FIG. 3 b is a front view of the screw in the device, and FIG. FIG. 4 is a sectional view of another embodiment according to the present invention. 1...Developing roller, 2...Elastic application member, 3...
...Elastic scraper, 4, 5... Screw, 1'
...Sleeve, 2'...Magnetic blade, 6...Magnetic roll, 7...Magnetic roller.

Claims (1)

[Claims] 1 a developing roller, a container for supplying a monocomponent developer to the developing roller, means for applying a thin layer of the supplied monocomponent developer to the developing roller, and after development,
and a means for removing the one-component developer from the developing roller at the position before the supply, and a means for transporting the removed one-component developer and above the position for supplying the one-component developer to the developing roller. A developing device characterized in that it has means for collecting into said container at said position.