JPS6270881A - Developing device - Google Patents

Abstract

PURPOSE:To sufficiently and electrostatically charge a toner and to obtain a clear image by forming a toner separating means for separating toner from a two-component developer held by a developer holding means and scattering the separated toner. CONSTITUTION:The toner separating means is provided with plural glid wires 4 consisting of tungsten or the like and N and S magnetic poles are formed on the fixed magnet body 3 of a developer carrier consisting of a sleeve 2 or the like on the opposite part to the wire 4 side. DC developing bias power supplies 9, 10 and AC developing bias power supplies 11, 12 are turned on and the two-component developer 6 is supplied from a tank 7 to a case body 5. The developer is rotated and agitated in accordance with the rotation of the sleeve 2 and the toner in the two-component developer 6 is sufficiently triboelectrificated and magnetic carrier is removed from the outer periphery of the sleeve by the action of N and S magnetic poles. The toner is scattered to the image carrier 1 on which an electrostatic latent image is formed by the action of the glid wires 4 to develop an image.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a developing device that forms a desired image using a two-component developer consisting of a magnetic carrier and a toner.

(Prior Art) Conventionally, a developing means for depositing a developer onto an image bearing member such as a photoreceptor drum and forming a desired image based on the developer is disclosed in, for example, Japanese Patent Publication No. 37-14798. A magnetic brush method using a two-component developer is widely used. This magnetic brush method is an extremely effective method that allows a clear image to be obtained with one development on the image carrier.

However, when performing multicolor development using two or more colors as disclosed in JP-A-54-81855, for example, the electrostatic latent image on the image carrier is mechanically rubbed with a magnetic brush.
The developer that initially adheres to the image carrier to form an electrostatic latent image of a certain color is scraped off by the magnetic brush at the stage of forming an electrostatic latent image of a different color. There is a problem in that the developer mixed in the color mixes into a developer container for forming another color.

In addition, a non-contact developing method that does not mechanically rub the electrostatic latent image formed on the image carrier is disclosed in Japanese Patent Application Laid-Open No. 54-43027, etc., but in this case, magnetic powder is developed. There is a problem in that it is difficult to produce a developer for forming clear color images because it is mixed into the developer.

In general, as a non-contact developing method using a -component non-magnetic developer, there are methods disclosed, for example, in JP-A-56-116060, JP-A-56-1651718, etc. When forming a thin layer of developer with a blade on the developing roller (hereinafter also referred to as "sleeve"), it is difficult to form a uniform layer, and
There is a problem in that a sufficient triboelectric charge cannot be applied to the developer, making it impossible to obtain a clear image.

(Problems to be Solved by the Invention) As described above, conventional developing means have problems such as being unable to apply sufficient triboelectric charge to the developer, making it difficult to form clear images.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a non-contact type developing device that can form a clear image by imparting sufficient triboelectric charge to the developer.

[Structure of the Invention] (Means for Solving the Problems) A developing device of the present invention includes a developer holding means for holding a developer made of a magnetic carrier and a toner, and a developer held by the developer holding means. The toner separating means separates toner from the developer and causes it to fly, and an image carrier selectively attaches the flying toner to the electrostatic latent image portion, which is separated from the developer by the toner separating means.

(for production) The operation of the developing device having the above structure will be explained below.

When the developing operation of this device is started, the toner in the developer held by the developer holding means is triboelectrically charged, and then only the toner is separated from the developer by the action of the toner separating means, and the toner is pre-electrostatically charged. It flies toward the image carrier on which the image is formed. Then, the flying toner selectively adheres to the electrostatic latent image portion, and a desired image is formed based on this.

(Example) A first example of the present invention will be described below with reference to FIG.

The developing device shown in the figure includes an image carrier 1, such as a photosensitive drum, on the outer periphery of which an electrostatic latent image is formed by a known appropriate means, and a developer disposed adjacent to the image carrier 1. The holding means 20, the toner separating means 30, and the developer holding means 2
The two-component developer 6 is composed of a magnetic carrier held by 0 and a coloring toner.

The developer holding means 20 includes a sleeve 2 made of a non-magnetic material, which is arranged parallel to and at a predetermined distance from the image carrier 1 and is rotatably supported in the direction of the arrow shown in the figure. , within this sleeve 2, and within this sleeve 2
a fixed magnet body 3 having a circular cross section disposed coaxially with the
A case body 5 is formed in which the sleeve 2 has an open portion on the image carrier 1 side and is formed to surround the outside of the sleeve 2. A tank 7 for supplying the image agent 6 is provided.

The toner separating means 30 includes a plurality of grid wires 4 made of tungsten or the like and arranged along the axial direction of the sleeve 2 in the opening of the case body 5. The fixed magnet body 3 is provided with N and Sla poles at a portion opposite to the grid wire 4 side.

Further, DC development bias power supplies 9 and 1 that apply a DC development bias voltage to the grid wire 4 and the sleeve 2 are provided.
AC developing power supply that applies 0 and AC developing voltage 11.12
are connected to each other.

In FIG. 1, reference numeral 8 denotes a detector which is disposed on the upper part of the case body 5 and optically detects the amount of two-component developer adhering to the outer periphery of the sleeve 2.

Next, the operation of the apparatus having the above configuration will be explained.

The DC development bias power supplies 9 and 10 and the AC development power supply 1
1.12 is turned on and the case body 5 is removed from the tank 7.
The two-component developer 6 is supplied to start the developing operation. As the sleeve 2 rotates in the direction of the arrow, this two-component developer 6
are rotated and stirred around the outer periphery of the sleeve 2 and rub against each other, whereby the toner in the two-component developer 6 is sufficiently charged and a portion of it adheres to the outer periphery of the sleeve 2 together with the magnetic carrier. Then, when the sleeve 2 further rotates and the two-component developer 6 attached to the outer periphery of the sleeve 2 reaches the vicinity of the N and S magnetic poles, the magnetic carrier in the two-component developer 6 becomes N.
, detach from the outer periphery of the sleeve 2 due to the action of the S magnetic pole. On the other hand, the toner attached to the outer periphery of the sleeve 2 reaches the vicinity of the grid wire 4 as the sleeve 2 rotates.
At this time, the amount of adhered toner is detected by the detector 8,
As a result, control is performed to keep the toner concentration constant.

The toner on the sleeve 2 that has reached the vicinity of the grid wire 4 forms an electrostatic latent image formed in advance from the outer periphery of the sleeve 2 by the action of the grid wire 4 to which a DC developing bias voltage and an AC developing voltage are applied. It flies toward the carrier 1 and selectively attaches to charged or non-charged portions of the electrostatic latent image, and by repeating this operation, the image is developed without contact.

Next, a second embodiment of the present invention will be described with reference to FIG. In the developing device shown in FIG. 2, parts having the same functions as those shown in FIG. 1 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

The device shown in FIG. 2 differs from the device shown in FIG. 1 in that a fixed magnet body 3- having N and S magnetic poles is provided inside the case body 5 and outside the sleeve 2. In this device as well, the fixed magnet 3- operates in the same manner as the fixed magnet 3, and can exhibit the same function as the device shown in FIG.

FIG. 3 shows a third embodiment of the present invention, and in this case as well, parts having the same functions as those shown in FIG. is omitted. The difference between the device shown in FIG. 3 and the device shown in FIG. 1 is as follows:
This is achieved by providing a rotating basket 13 inside the case body 5 and outside the sleeve 2, which is rotatable in the direction of the arrow in the figure. Then, the two-component developer 6 is sprinkled onto the sleeve 2 by a cascade method using the rotating basket 13 to cause frictional charging, and the toner in the two-component developer 6 is transferred to the sleeve 2.
The image is conveyed to the grid wire 4 side while adhering to the outer periphery of the image, and an image is formed based on the operation similar to that of the apparatus shown in FIG.

It goes without saying that the present invention is not limited to the embodiments described above, and that various modifications can be made within the scope of the invention.

[Effects of the Invention] According to the present invention described in detail above, the toner in the two-component developer can be sufficiently charged and caused to fly to the image carrier,
Based on this, it is possible to provide a current @ device that can obtain clear images.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram showing the first embodiment of the present invention;
The figure is a schematic explanatory diagram showing a second embodiment of the invention, and FIG. 3 is a schematic explanatory diagram showing a third embodiment of the invention. DESCRIPTION OF SYMBOLS 1... Image carrier, 2... Sleeve, 5... Case body, 6... Two-component developer, 20... Developer holding means, 30... Toner separation means. 5P12 Funeral diagram 3

Claims (2)

[Claims] (1) A developer holding means for holding a developer composed of a magnetic carrier and toner, a toner separating means for separating and flying the toner from the developer held by the developer holding means, and this toner separating means. A developing device comprising an image carrier that selectively attaches toner that is separated from a developer and flies to an electrostatic latent image portion. (2) The developing device according to claim 1, wherein the toner separating means includes a grid wire.