JPS59195260A - Magnetic toner developing device - Google Patents

Abstract

PURPOSE:To control the conveyance amount of toner and to prevent the toner from staying between an electrode and a conductive sleeve by providing the electrode opposite to the conductive sleeve, impressing a variable voltage to the electrode, and controlling an electric field produced between the electrode and conductive sleeve. CONSTITUTION:The pointed electrode 13 is provided at specific distance (h) from the surface of the sleeve 12, and the specific variable voltage is impressed between the sleeve 12 and electrode 13. Consequently, magnetic toner 14 has a charge by the electric field produced between the sleeve 12 and electrode 13 and is attracted to the electrode 13. For this purpose, the impressed voltage is controlled to a specific value to control the amount of toner which stays near the electrode 13, conveying a specific amount of toner. Consequently, even when the distance between the electrode 13 and sleeve 12 is set large, a voltage is impressed between the both to control the conveyance amount of the magnetic toner, preventing the toner from staying between the electrode and sleeve.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a developing device in an electrophotographic device or an electrostatic recording device, and more specifically, to a developing device in an electrophotographic device or an electrostatic recording device, and more specifically, to a developing device in an electrophotographic device or an electrostatic recording device.
This invention relates to improvements in toner developing devices.

fb) Background of the Technology Recently, magnetic toner developing devices using a magnetic l-toner as a developer have been used as developing devices for electrophotographic devices, instead of the conventional two-component developer consisting of toner and carrier. It is becoming more and more common. This is because with a two-component developer, the ratio of toner and carrier must always be kept at a predetermined value, and the developer cannot be used for a long time due to toner sticking to the surface of the carrier. be.

The case where electrophotographic development is carried out using such a magnetic toner will be explained with reference to FIG.

First, the surface of the recording drum 1 is coated with, for example, selenium (
An electrostatic latent image is formed on a photoreceptor made of Se) or the like at a predetermined location on the photoreceptor using a laser beam or the like. After that, a one-component magnetic 1-toner 2 in which magnetic powder is mixed in a resin is attached to the sleeve 4 around the magnetic roller 3 and brought close to the electrostatic latent image. Charge is injected. When the Coulomb attraction between the charged magnetic 1 hener 2 and the electrostatic latent image overcomes the magnetic force between the toner 2 and the magnetic roller 3, toner 1 to toner 2 adhere to the electrostatic latent image and development is performed. be exposed.

When transferring such a developed image to paper,
A rotating drum (not shown) with paper wrapped around it is provided at a predetermined distance opposite the recording drum, and a discharge with a polarity opposite to that of the toner is performed from the back side of the paper to charge the paper and place it on the photoreceptor. transfer the toner onto the paper.

By the way, in the development using such magnetic toner 2, in order to obtain sufficient image density, the recording drum 1 and the sleeve 4 are
It is necessary to set the interval between 0.2 and 1.0 sweetfish.

Therefore, if the amount of magnetic toner 2 to be conveyed becomes too large, the magnetic toner 2 will accumulate between the recording drum 1 and the sleeve 4, resulting in a decrease in print density and disturbances in print.

(C1 Prior Art and Problems Therefore, in the conventional magnetic toner developing device, as shown in FIG. 2, a metal member with a pointed tip called a doctor blade 5 is installed opposite the sleeve 4, and the doctor blade The amount of conveyance of the magnetic toner 2 is determined by adjusting the distance between the magnetic toner 5 and the sleeve 4 to a predetermined value.

In particular, the resistance of toner is 10 Ω-cm (measuring electric field 4
When using magnetic toner with high resistance (KV/cm) or more, the distance between the sleeve 4 and the recording drum 1 should be set at 0.2 to 0.
．． Must be 3. For this reason, it is necessary to make the distance between the doctor blade 5 and the sleeve 4 quite small, 0.1 to 0.15 mm.

Therefore, agglomeration of the toner 2 occurs between the doctor blade 5 and the sleeve 4, causing the toner 2 to harden, or foreign matter in the atmosphere mixes with the toner 2, making it easy for the gap between the doctor blade 5 and the sleeve 4 to become clogged. This has the disadvantage that it is difficult to transport the toner stably.

(dl OBJECT OF THE INVENTION The present invention eliminates the above-mentioned drawbacks, and provides an electrode corresponding to the doctor blade, which is attached from the surface of the sleeve to face the sleeve and separated from the sleeve by a predetermined distance, and between the electrode and the sleeve. The object of the present invention is to provide a novel magnetic toner developing device that can stably supply toner by applying a predetermined variable voltage to prevent toner from clogging between the electrode and the sleeve. .

tel Structure of the Invention In order to achieve the above object, a magnetic toner developing device of the present invention is a magnetic toner developing device comprising an electrically conductive sleeve and a magnetic roller housed within the sleeve. An electrode is provided facing the conductive sleeve, and a variable voltage is applied to the electrode to control the electric field generated between the electrode and the conductive sleeve, thereby controlling the amount of toner conveyed. It is characterized by this.

(fl Embodiment of the Invention An embodiment of the invention will be described in detail below with reference to the drawings.

FIG. 3 is a diagram schematically showing an embodiment of the magnetic toner developing device of the present invention.

Sleeve 12 around magnetic roller 11 as shown
An electrode 13 made of a metal member with a pointed tip is installed at a predetermined distance from the surface of the electrode. and sleeve 12
A predetermined variable voltage is applied between the electrode 13 and the electrode 13.

The toner used here has a resistance of 10
Ω-cm (A high-resistance toner with a measured electric field of 4 KV/cm or more shall be used.) -The development method is
The normal development method used in ordinary copying machines, etc. is used.

The case where development is carried out using such a magnetic toner developing device of the present invention will be described.

The magnetic toner 14 shown in FIG. 3 is attracted by the magnetic roller 11 and is conveyed while being adhered to the sleeve 12 around the magnetic roller 11. At this point, for example, sleeve 1
In order to set the distance between the sleeve 12 and the electrode 13 to be 0.4 to 0.6 m, which is larger than the conventional device, and to convey the same amount of toner as the conventional device, the sleeve 12 and the electrode 1
It is preferable to apply a DC voltage of 700 to 100 OV using the DC power supply 15 between 3 and 3.

In this way, electric charges are injected into the magnetic toner 14 by the electric field generated between the sleeve 12 and the electrode 13, so that the magnetic toner 14 has an electric charge and receives a force in the direction of adhering to the electrode 13.

This force is caused by electric field concentration on the electrode 13 side.
The closer it is to the electrode 13, the larger it becomes. Furthermore, if this force becomes larger than the conveyance force applied to the toner, the toner will no longer be conveyed.

Utilizing this fact, by controlling the voltage applied between the electrode 13 and the sleeve 12 to a predetermined value, the amount of toner remaining near the electrode 13 without being transported can be controlled, and the magnetic toner can be removed. It becomes possible to transport a predetermined amount.

As described above, according to the magnetic toner developing device of the present invention, the distance between the electrode 13 and the sleeve 12 is set to be more than twice the distance between the doctor blade 5 and the sleeve 4 in the conventional device. Even if the electrode 13 and sleeve 12
By applying a voltage between them, the amount of magnetic toner conveyed can be easily controlled. Therefore, the phenomenon of toner clogging between the doctor blade 5 and sleeve 4, which occurs in conventional devices, can be eliminated, and a predetermined amount of toner can be stably transported.

Furthermore, the above embodiments have been described using the case of a normal development method, and the power source 15 is directly connected to the electrode 13 as shown in FIG. In this case, the developing bias applied to the sleeve 12 may be divided by resistors and applied to the electrode 13.

(Effects of the Invention As described above, according to the magnetic l/toner developing device of the present invention, the distance between the electrode and the sleeve, which corresponds to a conventional doctor blade, can be made larger than that of the conventional device. This has the effect of providing a magnetic toner developing device that can stably transport 1 to fM of toner without causing the phenomenon of toner clogging between the electrode and the sleeve.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a magnetic toner developing device, FIG. 2 is a schematic diagram of a conventional magnetic 1-toner developing device, and FIG. 3 is a schematic diagram of a magnetic toner developing device of the present invention. In the figure, 1 is recording 1-ram, 2 and 14 are magnetic toner,
3 and 11 are magnetic rollers, 4 and 12 are sleeves, 5 is a doctor blade, 13 is an electrode, and 15 is a DC power source. Figure 1 Figure 21 1 Figure 3

Claims (1)

[Claims] A magnetic toner developing device comprising an electrically conductive sleeve and a magnetic roller housed within the sleeve, the developing device having an electrode facing the electrically conductive sleeve,
A magnetic material characterized in that the conveyance amount of the 1-ner is controlled by applying a voltage between the electrode and the conductive sleeve and controlling the electric field generated between the electrode and the conductive sleeve. Toner developing device.