JPH035584B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a developing device using the one-component magnetic toner of the present invention. Development methods using one-component magnetic toner are well known, but from the viewpoint of charge application, there are two methods: methods using low-resistance magnetic toner and attaching the toner to an electrostatic latent image by electrostatic induction or polarization; There is a method in which a resistive magnetic toner is charged by means such as injection or friction, and is made to adhere to an electrostatic latent image. On the other hand, when classified from the perspective of transporting and supplying magnetic toner to an electrostatic latent image, there are two methods: the so-called sleeve rotation method, in which the magnetic roll is fixed and the sleeve is rotated, and the so-called magnet rotation method, in which the sleeve is fixed and the magnetic roll is rotated. It is classified into two types. In electrophotographic copying, due to the demand for plain paper and faster speeds, a developing method using a sleeve rotation method using high-resistance magnetic toner is being considered, but in the above method, the toner attached to the electrostatic latent image, Development is influenced by toner of opposite polarity mixed in the toner layer or magnetic lines of force in a fixed magnetic field, and has various drawbacks such as disturbances in the peripheral area of the image, unevenness in the thickness of the developed toner layer, and low areal density. Therefore, there is a problem in that the final copies can only be of low quality. As a means of solving this problem, the inventors of the present invention performed imaging by rotating both the sleeve and the magnet roll. The developed images maintained excellent quality due to the rotation of the magnet roll, and the toner was transported only by the sleeve. It has been confirmed that excellent developing results can be obtained by incorporating the respective advantages of the sleeve rotation method and the magnet rotation method, which are maintained by the rotation of the sleeve. However, the following problems were found in the dual rotation system as described above. In other words, when using magnetic toner with a relatively high resistance value (10 ¹⁰ to 10 ¹⁶ Ω・cm), the image quality varies greatly depending on the rotation direction of the sleeve and magnet roll, the moving speed of the toner, the magnetic flux density of the magnet roll, etc. In addition, toner pools are more likely to form in the double-rotation method than in the sleeve rotation method, and the toner puddles grow over time, and this puddle is unstable. It was confirmed that the line quality gradually deteriorated during development. An object of the present invention is to provide a new developing device that eliminates the drawbacks of the above-mentioned two-rotation systems. The object of the present invention is that the resistance of the toner is 10 ¹⁰ ~
In a magnetic one-component developing device that uses magnetic toner of 10 ^{to 16} Ωcm and consists of a rotating magnet roll and a sleeve that rotates around it in the opposite direction to the magnet roll, the rotation speed of the sleeve is 200 to 900 mm/
sec, and the rotation speed of the magnetic roll is 500~
1000rpm, and the magnetic flux density of the magnet roll is 500rpm.
~1500 Gauss, and when the distance between the injection electrode that also serves as a toner layer thickness regulating plate and the surface of the developing sleeve is g ₁ , the distance g ₂ between the image sleeve and the photoreceptor surface is g ₂ = This is achieved by a developing device characterized in that injection electrodes are arranged so that g ₁ ±0.4 mm. The present invention will be described in detail below with reference to the drawings. FIG. 1 shows a schematic diagram of a developing system according to the present invention. 1 indicates a photosensitive drum. A charging corotron 2 uniformly charges the surface of the photoreceptor, and then an exposure unit 3 performs image exposure to form an electrostatic latent image. Next, the developed images that have passed through the developing unit 4 and become visible are transferred onto the recording paper 8 by the transfer corotron 5. The transferred image passes through a fixing device 7 and finally becomes a copy. On the other hand, the toner remaining on the surface of the photosensitive drum 1 after passing through the transfer section is cleaned by the cleaning unit 6, and the toner enters the next copying cycle again. FIG. 2 is a schematic diagram of a conventional dual rotary type developing machine. This developing machine has a rotatable cylindrical sleeve 4-4
It has a structure in which a brush made of magnetic toner is formed on a developing roll in which a rotatable magnet roll 4-5 is arranged. Now, determine the distance between the photoreceptor drum surface and the sleeve surface.
g ₂ ′ When the distance between the sleeve surface and the toner layer thickness regulating plate 4-2 is g ₁ , and the relationship is set to satisfy g ₁ ≧ g ₂ , with respect to the moving direction a of the photoreceptor drum 1, When the sleeve is rotated in the b direction and the magnet is rotated in the e direction, a toner pool is formed in the diagonally shaded area x.
Similarly, when the sleeve is rotated in the d direction and the magnet is rotated in the c direction with respect to the moving direction a of the photosensitive drum, a toner pool is similarly formed in the diagonally lined Y area. This phenomenon is achieved by rotating the sleeve and magnet in the same direction, which reduces the movement of toner by the sleeve.
This occurs because the toner moves in the opposite direction to the sleeve as it rotates due to the rotation of the magnet. Table 1 shows trends in ease of toner accumulation and image quality when the rotating direction and speed of the sleeve and magnet roll are fixed.

【table】 rule transfer

Claims (1)

[Claims] 1. In a magnetic one-component developing device that uses magnetic toner with a toner resistance of 10 ¹⁰ to 10 ¹⁶ Ω·cm and is composed of a rotating magnet roll and a sleeve that rotates around the magnet roll in the opposite direction to the magnet roll, the sleeve The rotation speed of the magnet roll is 200 to 900 mm/sec, the rotation speed of the magnet roll is 500 to 1000 rpm, the magnetic flux density of the magnet roll is 500 to 1500 Gauss, and the injection electrode also serves as a toner layer thickness regulating plate. The injection electrode is arranged so that when the distance between the developing sleeve and the surface is g ₁ , the distance between the developing sleeve and the photoreceptor surface is g ₂ = g _{1 ±} 0.4 mm. A developing device.