JPH0746247B2 - Development device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to, for example, a developing device for forming a toner thin layer of one component on a developing roller by a coating blade and developing the toner.

(Prior Art) A developing device of this type includes a developing roller facing a photoconductor, and a coating blade contacting the developing roller forms a toner layer on the peripheral surface of the developing roll. By supplying a developing bias from a developing bias power source (not shown) so as to face the electrostatic latent image formed on the photoconductor, toner is supplied to the electrostatic latent image for visualization.

This developing device basically uses a high-resistance one-component toner, and the toner is charged by frictional charging between the toner and the developing roller and between the toner and the coating blade.

Further, the toner is also conveyed by the electrostatic attraction between the toner and the developing roller and rotates as the developing roller rotates. In this case, there is no need for magnetic conveyance as in two-component development or magnetic one-component.

Therefore, development using high-resistance non-magnetic toner can be realized with a very simple structure, which is very advantageous in terms of cost and is the most suitable developing device for colorization.

(Problems to be Solved by the Invention) However, in the related art, among the toners held on the developing roller, toners that do not contribute to development, that is, the amount of charge of the toners held on both ends of the developing roller and other than the both ends. Since the charge amounts of the toners that contribute to the development are equalized, if a development bias is applied during the development, the toner that is unnecessary for the development may fly or fall off and the inside of the copying machine becomes dirty. there were.

[Structure of the Invention] (Means for Solving Problems) In order to solve the above problems, the present invention provides an image bearing member carrying an electrostatic latent image and a surface of the image bearing member facing the image bearing member. A developing roller for supplying the non-magnetic one-component developer to the electrostatic latent image on the image carrier by rotating while carrying the non-magnetic one-component developer; and a developing roller pressed against the surface of the developing roller, Of the non-magnetic one-component developer frictionally charged on the surface of the developing roller and forming a developer layer on the surface of the developing roller, and among the non-magnetic one-component developer charged by the blade, the developing roller Of the non-magnetic one-component developer carried on both ends of the non-magnetic one-component developer is larger than the charge amount of the non-magnetic one-component developer carried outside the both ends of the developing roller. A charging member that charges the agent It is characterized in that it comprises.

(Operation) By the above means, the developer not required for the development on the developer holder is prevented from flying or dropping from the developer holder even when the developing bias is applied.

(Example) Hereinafter, the present invention will be described with reference to an example shown in the drawings.

FIG. 3 shows an electronic copying machine, in which 1 is a copying machine main body. A photoconductor 2 as an image holding member is rotatably provided in the direction of an arrow at a substantially central portion of the main body 1. A charger 3, an imaging lens array 4, a developing device 5, a transfer charger 6, a cleaner 7, and a charge eliminator 8 are sequentially arranged around the periphery of the photoconductor 2 along the rotation direction thereof. There is. An optical system 9 for exposing a document is provided on the upper side of the main body 1, and a paper feed cassette 10 is mounted on the lower side of the main body 1. This paper cassette 10
A sheet is supplied from the sheet, and the sheet is conveyed along the conveying path 11. A registration roller 12, a fixing device 13, and a paper discharge roller 14 are arranged in the transportation path 11 along the transportation direction of the paper. Reference numeral 15 is an output tray, and 16 is a document table.

Then, at the time of image formation, the optical system 9 causes the document table 16
The upper original is irradiated with light, and the reflected light is imaged on the photoconductor 2 via the imaging lens array 4 to form an electrostatic latent image. Toner is supplied to the electrostatic latent image by the developing device 5 to visualize it. On the other hand, at this time, the paper is supplied from the paper feed cassette 10 and sent between the photoconductor 2 and the transfer charger 6 to transfer the visible image on the photoconductor 2 to the paper. After that, the paper is conveyed to the fixing device 13 along the conveyance path 11, where it is fixed and then discharged onto the paper discharge tray 15 via the paper discharge roller 14.

Next, the developing device 5 will be described in detail. As shown in FIG. 2, the developing device 5 includes a developing unit 21, in which the non-magnetic toner 22 of one component as a developer is stored, and a mixer 23 and a supply roller 24 are provided. Further, a developing roller 25 as a developer holder is provided. The developing roller 25 faces the photoconductor 2 and rotates at a relative speed of zero relative to the photoconductor 2. Further, in the developing unit 21, an upper end is held in a conductive state by a holder 26, and a lower end is provided with a coating blade 27 as a coating member that abuts against the developing roller 25, and the developing roller 25 has The recovery blade 28 is in contact with the lower side.

The surface of the developing roller 25 is uniformly blasted by sun blast or the like, and electroless nickel plating is applied thereon.

By the way, both end portions of the developing roller 25 are unnecessary portions for development and are unnecessary portions originally, but they cannot be eliminated due to the structure of the developing device 5. As shown in FIG. 1, charging members 31, 31 are provided at both ends of the developing roller 25.
Is provided. As the charging members 31, 31, members having good charging characteristics, for example, fluororesin, epoxy resin, or tin plating are used, and are coated or plated.

At the time of development, the toner 22 is supplied to the developing roller 25 by the rotation of the supply roller 24. The toner 22 is pressed by the coating blade 27 to form a toner layer, and then the electrostatic latent image on the photoconductor 2 is formed. This is visualized by facing. Then, the toner remaining on the developing roller 25 is collected in the developing unit 21 via the collecting blade 28.

The toner held at both ends of the developing roller 25 at the time of this development has a larger charge amount than the toner held in the other portions by the charging members 31 and 31 and flies or drops even when a developing bias is applied. There is nothing to do.

The present invention is not limited to the above-mentioned one embodiment, and the
As shown in the drawing, the charging members 41, 41 may be coated or plated on both ends of the coating blade 27.

Further, as shown in FIG. 5, the charging members 51, 51 may be pressed against both ends of the developing roller 25.

[Effects of the Invention] As described above, according to the present invention, it is possible to prevent the developer, which does not contribute to the development on the developer holder, from flying and falling off, and to prevent dirt inside the apparatus main body and dirt such as a transfer material. The effect is that it can be prevented.

[Brief description of drawings]

1 to 3 show an embodiment of the present invention. FIG. 1 is a perspective view showing a developing roller, FIG. 2 is a block diagram showing a developing device, and FIG. 3 is a schematic view showing a copying machine. 4 is a perspective view showing a first other embodiment, and FIG. 5 is a perspective view showing a second other embodiment. 2 ... Photosensitive member (image holding member), 25 ... Developing roller (developer holding member), 27 ... Coating blade (coating member), 31, 41, 51 ... Charging member.

Claims (1)

[Claims] 1. An image bearing member carrying an electrostatic latent image, and the electrostatic bearing on the image bearing member by rotating while carrying a non-magnetic one-component developer on the surface facing the image bearing member. A developing roller that supplies a non-magnetic one-component developer to the latent image, and a non-magnetic one-component developer that is pressed against the surface of the developing roller to frictionally charge the non-magnetic one-component developer on the surface of the developing roller and to the surface of the developing roller. Of the non-magnetic one-component developer charged by the blade forming the developer layer and the non-magnetic one-component developer carried on both ends of the developing roller, the charge amount of the non-magnetic one-component developer is equal to that of the developing roller. A developing device, comprising: a charging member that charges the non-magnetic one-component developer so as to be larger than a charge amount of the non-magnetic one-component developer carried outside the both end portions.