JPH0635325A - Developing device for electrophotographic printer - Google Patents

Abstract

PURPOSE:To simplify the construction of the device, to make it light weight and to lower the cost by providing a toner carrier consisting of a belt shaped magnetic film feeding magnetic toner on an image carrier with an electrostatic latent image which is visualized by the electrified magnetic toner. CONSTITUTION:The magnetic film 1 is rotated in the direction of the arrow A while receiving tension force by a pair of rolls 2. Because the distance between a tip of a doctor blade 3 and the surface of the magnetic film 1, that is the doctor blade gap is set to be a specified value, the uniform thin layer is formed by the magnetic toner 7. A toner image 8 is formed by having the magnetic toner 7 stick to the electrostatic latent image because the electrostatic latent image is formed by an electrifying exposure part on the surface of the image carrier 4 and the electrostatic attraction force between the electrostatic latent image and the magnetic toner 7 is greater than the restraint of a magnetic field. Because the magnetic toner 6 is fed in the direction of the doctor blade 3 by the rotation of a mixer 5 in the direction of the arrow B, this action is repeated as long as there is any magnetic toner 6 in a toner tank 9. Thus the construction of the developing device is simplified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for an electrophotographic printer, and more particularly to a developing device for an electrophotographic printer which supplies magnetic toner with a strip-shaped magnetic film.

[0002]

2. Description of the Related Art FIG. 2 is a sectional view showing an example of a developing device of a conventional electrophotographic printer. Referring to FIG. 2, in the developing device of the conventional electrophotographic printer, the magnet roll 12 generates a magnetic field. This magnetic field rotates in the direction of arrow C as the magnet roll 12 rotates in the direction of arrow D. The magnetic toner 16 sticks to the surface of the metal sleeve 11. Magnetic toner 1 adsorbed on the surface of the sleeve 11
The magnetic field 7 generated by the magnet roll 12 receives a restraining force. Doctor blade 13 tip and sleeve 11
Since the distance to the surface, that is, the doctor blade gap is set to a predetermined value, the magnetic toner 17 forms a uniform thin layer. An electrostatic latent image is formed on the surface of the image carrier 14 by a charging exposure unit (not shown), and the electrostatic attraction between the electrostatic latent image and the magnetic toner 17 is larger than the binding force of the magnetic field. A toner image 18 is formed by adhering to the electrostatic latent image. Since the magnetic toner 16 is supplied in the direction of the sleeve 11 by the rotation of the mixer 15 in the direction of arrow E, the above operation is repeated as long as the magnetic toner 16 remains in the toner tank 19.

[0003]

A metal sleeve and a magnet roll are indispensable for the developing device of this conventional electrophotographic printer. However, since these metal sleeves and magnet rolls are expensive and heavy, they hinder the weight reduction and cost reduction of the developing device. Furthermore, the structure becomes complicated because a rotating mechanism of the magnet roll is required.

[0004]

SUMMARY OF THE INVENTION A developing device for an electrophotographic printer according to the present invention comprises a strip-shaped magnetic film for supplying the magnetic toner to an image carrier having an electrostatic latent image visualized by the magnetic toner. A toner carrier is provided.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the present invention. Figure 1
Referring to, in the developing device of this electrophotographic printer, the magnetic toner 6 stored in the toner tank 9 is adsorbed on the surface of the magnetic film 1. At this time, the magnetic toner 7 is restrained by the magnetic field of the magnetic film 1.
The magnetic film 1 rotates in the direction of arrow A while receiving a tensile force by the roller pair 2. Since the distance between the tip of the doctor blade 3 and the surface of the magnetic film 1, that is, the doctor blade gap is set to a predetermined value, the magnetic toner 7
Form a uniform thin layer. An electrostatic latent image is formed on the surface of the image carrier 4 by a charging exposure unit (not shown), and the electrostatic attraction between the electrostatic latent image and the magnetic toner 7 is larger than the binding force due to the magnetic field. The toner image 8 is formed by adhering to the electrostatic latent image. Since the magnetic toner 6 is supplied in the direction of the doctor blade 3 by the rotation of the mixer 5 in the direction of the arrow B, the above operation is repeated as long as the magnetic toner 6 remains in the toner tank 9.

[0006]

As described above, according to the present invention,
Since the structure of the developing device is simplified by providing the toner carrier composed of the band-shaped magnetic film for supplying the magnetic toner to the image carrier having the electrostatic latent image visualized with the charged magnetic toner, the developing device is simplified. Can be made lighter and less expensive.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a configuration of a conventional example.

[Explanation of symbols]

 1 magnetic film 2 roller pair 3 doctor blade 4 image carrier 5 mixer 6,7 magnetic toner 8 toner image 9 toner tank

Claims (1)

[Claims] 1. A developing device for an electrophotographic printer, comprising: a toner carrier made of a strip-shaped magnetic film for supplying the magnetic toner to an image carrier having an electrostatic latent image visualized with the magnetic toner. apparatus.