JPH01227174A - Developing device - Google Patents

Abstract

PURPOSE:To easily set a developing agent layer carrying body in a state where the carrying body is not brought into contact with an electrostatic latent image surface and, at the same time, the same picture quality as that obtained when two-component development is made by causing charged insulating magnetic toner to be scattered between electrodes and adhere to and develop the picture part of the latent image. CONSTITUTION:In a developing area, insulating magnetic toner 7 is scattered over a developing agent layer carrying body 9 while the toner makes reciprocating movements along the alternating magnetic field produced between electrodes isolated from each other. When an electrostatic latent image 11 approaches the scattered toner 7, the toner 7 is attached to the latent image surface by an electrostatic force and the latent image is developed. The toner 7 which does not contribute to the development is passed through the developing area while the toner repeats the reciprocating movements and again moved to a developing agent hopper 6 by the magnetic force of a magnet roller 8. Therefore, the clearance between the developing agent layer carrying body 9 and the electrostatic latent image holding body 1 can be set larger and, accordingly, non-contacted development in which the carrying body 9 and holding body 11 are easily settable can be realized and picture which are less in photographic fog, etc., can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device, and more particularly to a one-component non-contact developing device that uses an insulating magnetic toner in a developing device such as an electrophotographic device.

[Prior Art] Conventionally, as an electrophotographic developing device, there has been a magnetic brush method described in, for example, U.S. Pat. No. 2,874,063, U.S. Pat. No. 2,221,776, and U.S. Pat. A large number of development devices are known based on the cascade method, the powder cloud method, the fur brush method, etc. All of these developing devices are relatively stable and can easily produce images with excellent image quality.

[Problems to be Solved by the Invention] However, although the developing devices based on the above-described developing methods have excellent features, they also have common drawbacks due to the use of two-component developers. That is, the toner can acquire an electric charge due to mutual friction between the toner and the carrier, but the toner composition adheres to the carrier surface, causing a deterioration in the amount of charge of the toner. The mixing ratio of the carrier must be adjusted within a predetermined range, but the mixing ratio may fluctuate and deviate from the predetermined range due to long-term use. A control mechanism is required, iron powder or glass beads with a diameter of several tens of microns are used as a carrier agent, but when they rub against the surface of the photoreceptor, they are mechanically damaged, and the developing device is relatively large. For example, it may cause problems.

In order to avoid the above drawbacks, various one-component development methods using only toner as a developer have been proposed. for example,
U.S. Patent No. 3152012, U.S. Patent No. 373
There is an impression development method described in the specification of No. 1146 and the like. This is to form a toner layer on the impression roller by bringing a doctor blade supported by a spring into contact with the surface of the impression roller, which is a developer layer carrier. However, in a developing device based on the above-described developing method, the toner is a charged insulating toner and is not in contact with an electrostatic latent image carrier (for example, a photoreceptor drum, etc.). The present invention is intended to solve these problems, and it is difficult to set the mechanical settings when bringing the developer layer carrier into contact with the latent image surface. The purpose is -
Although the developing device is based on a component development method, the developer layer carrier and the electrostatic latent image surface are not in contact with each other, and the setting is easy.
An object of the present invention is to provide a developing device that can obtain image quality equivalent to that of two-component development.

[Means for Solving the Problems] The developing device of the present invention has internal rotating magnets whose outer peripheral surfaces are alternately magnetized with magnetic poles of different polarity, and has a plurality of electrodes insulated from each other in the developing region. The developer layer carrier is opposed to the electrostatic latent image carrier with a development gap larger than the thickness of the developer layer, and means is provided for applying an alternating voltage to a group of electrodes electrically insulated from each other. It is characterized by:

[Function] According to the above configuration of the present invention, the insulating magnetic toner is produced by rotating the magnet which is located inside and has magnetic poles of different polarity alternately magnetized on the outer circumferential surface. , can move on the surface of the developer layer carrier in a direction opposite to the direction of rotation. At this time, the insulating magnetic toner is charged by frictional action with the surface of the developer layer carrier, frictional action with a blade for regulating the thickness of the developer layer, or some other method (eg, corotron irradiation, etc.). The charged insulating magnetic toner is caused to fly between the electrodes by an alternating electric field generated by applying an alternating voltage to a plurality of electrodes that are electrically insulated from each other in the development area, and is applied to the image area of the electrostatic latent image. It is attached and developed by electrostatic force. The insulating magnetic toner that does not contribute to development passes through the development area and moves while being attracted onto the carrier by the magnetic force of the magnet inside the developer layer carrier.

[Example code] Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a diagram showing a cross section of a part of a developer layer carrier in a developing device of the present invention. The support member 1 is a roll made of a non-magnetic material, such as stainless steel or aluminum. An insulator layer 2 is thinly coated on the support member 1, and an electrode 3 is further formed on the insulator layer 2.

The electrode 3 can be formed by vapor-depositing an electrode material over the insulating layer, or by etching a thin layer. FIGS. 2(a) and 2(b) are diagrams showing the electrode group of the developer layer carrier used in the example of the present invention and the state of application of an alternating voltage, and FIG. 2(C) is a diagram showing the alternating electric field in FIG. FIG. 2 is a diagram showing the situation using electric lines of force. (a) shows an electrode 3a provided in an comb-like shape parallel to the sub-scanning direction of the developer layer carrier;
3b, an alternating voltage is applied by an external power supply 4 to ν.

In (b), an alternating voltage is applied between electrodes 3a and 3b provided in a comb-tooth shape parallel to the scanning direction of the developer layer carrier. The arrangement of the electrode group is not limited to those shown in (a) and (b), but may be any arrangement that can cause the developer to fly uniformly in the development area. The direction of the electric force lines 5 shown in (C) changes over time at a constant period, and the pre-charged developer flies through the development gap depending on the direction of the electric field and the charged polarity. Repeat the back and forth motion. FIG. 3 is a diagram schematically showing the developing device of the present invention. Insulating magnetic toner 7 is supplied from a developer hopper 6, and the toner is transported by rotating mag rollers 8 whose outer peripheral surfaces are alternately magnetized with magnetic poles of different polarity in the direction of arrow A in the figure. It can be moved on the surface of the developer layer carrier 9 in the direction of arrow B in the figure.

The developer layer carrier 9 is opposed to the electrostatic latent image carrier 11 with a gap larger than the thickness of the insulating magnetic toner 7 regulated by the doctor blade 10 . The insulating magnetic toner 7 is made of polyethylene resin, acrylic resin,
Carbon black is blended into a resin such as epoxy resin, polyester resin, or a copolymer thereof, and a magnetic material is further mixed at a ratio of 40 to 60% by weight, pulverized,
It is classified. Further, the insulating magnetic toner 7 is not only regulated in the thickness of the toner layer by the doctor blade 10, but also charged by frictional charging. During charging, the polarity is determined by the materials of the doctor blade 10 and the insulating magnetic toner 7. It is also charged by frictional action with the developer layer carrier 9. mag roller 8
The magnetic poles are arranged in a symmetrical 8-pole arrangement. The developer layer carrier 9 is made by coating polyimide with a thickness of several microns on an aluminum roll with a diameter of 20 mm, and further depositing copper with a thickness of several microns to several tens of microns on top of it.
Electrodes are formed by etching. Electrode is 0.3mm
It has a width of 0.3+ ohm pitch, and an alternating voltage of 600 square meters is applied at a frequency of 10 to 1000 Hz. The electrostatic latent image holder 11 is composed of a metal roll 12 made of aluminum or the like and a photoreceptor layer 13. In this embodiment, an organic photoreceptor is used and rotates at a speed of 60 degrees/second.

The electrostatic latent image holder 11 has a surface potential of -600 to -80 in advance.
It is charged to 0V and a latent image is formed by an optical writing system such as a laser.

According to such a configuration, in the developing region, the insulating magnetic toner flies over the developer layer carrier while reciprocating along the alternating electric field generated between the mutually insulated electrodes. At this time, when the electrostatic latent image approaches the flying insulating magnetic toner, the insulating magnetic toner is developed due to the force acting on it to move toward the latent image surface due to electrostatic force. The insulating magnetic toner that does not contribute to development passes through the development area while repeating reciprocating motion, and is moved to the developer hopper again by the magnetic force of the mag roller.

[Effects of the Invention] As described above, although the developing device of the present invention performs -component development, the gap between the developer layer carrier and the electrostatic latent image carrier can be made large, and the developer layer carrier It was possible to realize non-contact development with easy setting of the electrostatic latent image holder, and to obtain images with little fogging. Furthermore, since the developer flies in the developing area, it is possible to prevent deterioration of the developing device due to adhesion of the developer to the developer layer carrier, and also to prevent mechanical damage to the electrostatic latent image carrier. have an effect.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a cross section of a part of the developer layer carrier in the developing device of the present invention, and FIGS. 2(a) and (b) are electrodes of the developer layer carrier used in the embodiment of the present invention. Figure 2 (C) is a diagram showing the state of the alternating electric field when the alternating voltage is applied in Figure (a) using electric lines of force. 1 is a diagram schematically showing a developing device of the present invention. 1: Support member 2: Insulator layer 3: Electrode 4: External power source 5: Electric lines of force 6: Developer hopper 7: Insulating magnetic toner 8: Tuna, -ra 9: Developer layer carrier 10: Doctor blade 11 : Electrostatic latent image holder 12 : Metal roll 13 : Photoreceptor layer and above Applicant Seiko Epson Corporation (Q)
(b) \1 (C) Figure 2

Claims (2)

[Claims] (1) In a developing device that visualizes an electrostatic latent image carrier carrying an electrostatic latent image using a powder developer, a rotating magnet internally has magnetic poles of different polarity alternately magnetized on its outer circumferential surface. has
A developing device in which a developer layer carrier consisting of a plurality of electrodes electrically insulated from each other in a developing region is opposed to an electrostatic latent image carrier with a development gap larger than the thickness of the developer layer. A developing device further comprising means for applying an alternating voltage to the electrode group. (2) The developing device according to item 1, wherein the developer is an insulating magnetic toner.