JPH0416114B2 - - Google Patents

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 on an image bearing member such as a photoreceptor drum and forming a desired image based on the developer is disclosed in Japanese Patent Publication No. 14798/1983, for example. 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, so the image The developer that initially adheres to the carrier to form an electrostatic latent image of one color is scraped off by the magnetic brush at the stage of forming an electrostatic latent image of another color, and is also scraped off. There is a problem in that the developer gets mixed into the 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 was disclosed in Japanese Patent Laid-Open No. 54-43027.
However, since magnetic powder is mixed into the developer in this case, it is difficult to manufacture a developer for forming clear color images. There is.

Furthermore, as a non-contact development method using a one-component non-magnetic developer, there are methods disclosed in, for example, JP-A-56-116060, JP-A-56-165171, 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 it is difficult to apply sufficient triboelectric charge to the developer. There is a problem in that it is not possible to obtain a clear image.

(Problems to be Solved by the Invention) As mentioned 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) The developing device of the present invention includes a conveying means for holding and conveying a developer made of a magnetic carrier and toner;
a removing means that uses magnetic action to separate and remove only the magnetic carrier from the developer being conveyed by the conveying means; and after the magnetic carrier is removed by the removing means, it is held and conveyed by the conveying means. a flying means for flying the toner;
The image bearing member selectively attaches the toner ejected by the ejecting means to the electrostatic latent image portion.

(Function) The function of the developing device having the above configuration will be explained below.
When the developing operation of this device is started, the toner in the developer conveyed by the conveying means is triboelectrically charged, then the magnetic carrier is separated from this developer by the magnetic action of the removing means, and the toner is further removed by the flying means. Only the electrostatic latent image flies toward the image carrier on which an electrostatic latent image is formed in advance. 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 removing means 30 disposed adjacent to the image carrier 1. A developer conveying means 20 including
and a flying means 40, and a two-component developer 6 consisting of a magnetic carrier and a coloring toner held by the developer holding means 20.

The conveyance 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. Inside sleeve 2,
In addition, a fixed magnet body 3 functioning as a removing means 30 having a circular cross section is disposed coaxially with the sleeve 2, and a portion of the sleeve 2 on the image carrier 1 side is open and surrounds the outside of the sleeve 2. The sleeve 2 is provided with a case body 5 and a tank 7 for supplying a two-component developer 6 from the upper part of the case body 5 to the outer periphery of the sleeve 2.

The flying means 40 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 S magnetic poles at a portion opposite to the grid wire 4 side.

Further, the grid wire 4 and the sleeve 2 are connected to DC development bias power supplies 9 and 10 that apply a DC development bias voltage, and AC development power supplies 11 and 12 that apply an AC development voltage, respectively.

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 attached to the outer periphery of the sleeve 2.

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

While turning on the DC developing bias power supplies 9 and 10 and the AC developing power supplies 11 and 12, the tank 7 is turned on.
Then, the two-component developer 6 is supplied into the case body 5 and the developing operation is started. As the sleeve 2 rotates in the direction of the arrow, the two-component developer 6 rotates and is stirred around the outer periphery of the sleeve 2 and rubs against each other. As a result, the toner in the two-component developer 6 is sufficiently charged.
A part of it is attached to the outer periphery of the sleeve 2 together with the magnetic carrier. Then, the sleeve 2 rotates further, and the two-component developer 6 adheres to the outer periphery of the sleeve 2.
When the magnetic carrier reaches the vicinity of the N and S magnetic poles, the magnetic carrier in the two-component developer 6 moves to the sleeve 2 due to the action of the N and S magnetic poles.
detach from the outer periphery. On the other hand, the toner adhering to the outer periphery of the sleeve 2 reaches the vicinity of the grid wire 4 as the sleeve 2 rotates, but at this time, the amount of adhering 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 is transferred to the image carrier on which an electrostatic latent image has been previously formed 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. 1 and selectively attaches to a charged portion or an uncharged portion of the electrostatic latent image,
By repeating such operations, the image is developed without contact.

Next, a second embodiment of the present invention will be described with reference to FIG. In addition, in the developing device shown in FIG.
Components 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 body 3'
operates in the same manner as the fixed magnet body 3, and can exhibit the same functions 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 device shown in Figure 3 is the first
The difference from the device shown in the figure is that a rotating basket 13 is provided 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 electrification, and the toner in the two-component developer 6 is conveyed to the grid wire 4 side while adhering to the outer periphery of the sleeve 2. Thereafter, images are formed based on the same operations as in the case 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, only the toner in the two-component developer can be sufficiently charged and made to fly to the image carrier, and based on this, a clear image can be obtained. It is possible to provide a developing device that can.

[Brief explanation of drawings]

Fig. 1 is a schematic explanatory diagram showing a first embodiment of the present invention, Fig. 2 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. It is a schematic explanatory diagram. DESCRIPTION OF SYMBOLS 1... Image carrier, 2... Sleeve, 5... Case body, 6... Two-component developer, 20... Conveyance means,
30...Removal means.

Claims (1)

[Scope of Claims] 1. A conveying means for holding and conveying a developer consisting of a magnetic carrier and toner, and a method for separating and removing only the magnetic carrier from the developer conveyed by the conveying means by magnetic action. a removing means; a flying means for flying the toner held and conveyed by the conveying means after the magnetic carrier has been removed by the removing means; and a flying means for flying the toner held and conveyed by the conveying means; 1. A developing device comprising: an image carrier that selectively adheres to the image bearing member; 2. The developing device according to claim 1, wherein the flying means includes a grid wire.