JPH05165340A - Developing device - Google Patents

Abstract

PURPOSE:To always supply toner having uniform electric charge and to secure stable printing quality by providing a sub sleeve roller for attracting the developer of a main sleeve roller and a blade for scraping the developer. CONSTITUTION:Since the developer containing the toner which is electrostatically charged to be positive has magnetism, it is attracted to the main sleeve roller 5 because of the magnetic force of a fixed magnet 3, and moved with the rotation of a stainless cylinder 4. At such a time, the surface of the roller 5 is uniformly coated by a regulating plate 6, a photosensitive drum 7 is irradiated with a laser beam, and an image is developed only at a part where the charge is neutralized. The developer on the sleeve is attracted by the magnetism of the S pole of the roller 11 at the N pole-N pole connection part of the roller 5, whereby all the developer is attracted. The blade 12 is in contact with the sub sleeve roller 11, so that the attracted developer is scraped and fed to a stirring roller 2 again, and it is electrostatically charged again to be fed to the roller 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device, and more particularly to a developing device for a printing apparatus using an electrophotographic recording system using toner.

[0002]

2. Description of the Related Art FIG. 2 shows an example of prior art. This Figure 2
In the conventional example shown in (1), the toner replenished from the upper portion of the developing device 51 is sent to the stirring roller 52 and is positively charged by friction with the carrier. The main sleeve roller 55 is composed of a fixed magnet 53 and a stainless cylinder 54. The developer composed of the positively charged toner and the magnetic carrier is attracted to the magnetic main sleeve roller 55. The surface of the main sleeve roller 55 is uniformly coated with the attracted developer by the regulation plate 56.

The photosensitive drum 57 has a primary charger 58.
The surface is uniformly positively charged by the positive corona discharge, and the charge is neutralized only in the portion irradiated by the semiconductor laser light 59. The toner on the surface of the main sleeve roller 55 is developed only on the portion of the photosensitive drum 57 where the charge is neutralized by the action of the voltage applied between the photosensitive drum 57 and the main sleeve roller 55, and the surface of the photosensitive drum 57 is developed. A toner image is formed on.

[0004]

In the above-mentioned conventional developing device, the developer coated on the surface of the main sleeve roller is supplied only to the semiconductor laser irradiation portion on the surface of the photosensitive drum. On the other hand, after the development, the toner having a new charge is coated on the surface of the main sleeve, but the same developer may always remain on the surface of the main sleeve in other portions (portions not irradiated by the laser). In other words, when a fixed size paper is always used, the developer on the surface of the main sleeve is always supplied with new toner for this fixed size width, but otherwise remains on the sleeve without being consumed forever.
This leads to a situation where the charge gradually decreases. When a wide size paper is used in this state, the old toner has a lower charge, so that the developing efficiency is lower than that of the new toner and the density becomes uneven, resulting in poor printing quality.

[0005]

OBJECTS OF THE INVENTION It is an object of the present invention to provide a developing device in which the disadvantages of the conventional example are improved and, in particular, a stable printing quality is secured.

[0006]

According to the present invention, a sub-sleeve roller for adsorbing the developer of a main sleeve roller and a blade for scraping off the developer of the sub-sleeve roller in a developing device of a printing apparatus using an electrophotographic system. It has a configuration of preparing. This aims to achieve the above-mentioned object.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, the toner replenished from the upper portion of the developing device 1 is positively charged by friction while being stirred by the stirring roller 2. The main sleeve roller 5 is composed of a fixed magnet 3 and a stainless cylinder 4. The developer containing the positively charged toner has magnetism. Therefore, the magnetic force of the fixed magnet 3 attracts the main sleeve roller 5. The adsorbed developer moves as the stainless cylinder 4 rotates. At this time,
The surface of the main sleeve roller 5 is uniformly coated by the regulation plate 6, and the portion of the photosensitive drum 7 irradiated with the laser beam is developed only on the portion where the charge is neutralized.

The developer on the sleeve is attracted to the magnetism of the S pole on the sub-sleeve roller 11 at the N pole-N pole connection portion of the main sleeve roller 5, and is entirely attracted to the sub-sleeve roller 11. The blade 12 is in contact with the sub-sleeve roller 11, and the sub-sleeve roller 1
The developer No. 1 is scraped off and sent to the stirring roller 2 again, recharged and sent to the main sleeve roller 5. The sub-sleeve roller 11 is partitioned to prevent the replenishment toner from adsorbing.

Here, the developing efficiency of the toner whose charge is remarkably lowered becomes extremely poor. That is, the developing efficiency of the portion where the electric charge is neutralized by irradiating the laser on the photosensitive drum 7 is extremely different depending on the old and new toner. There are several causes of uneven density in the page, but the difference in the charge amount of the toner has a great influence.

In the embodiment, since the main sleeve roller 5 is always supplied with the toner having a uniform charge charged by the agitating roller 2, the developing efficiency for the photosensitive drum 7 is not suitable for changing the paper size. It is irrelevant and constant, and density unevenness can be prevented, and stable printing quality can be secured.

[0011]

As described above, according to the present invention, all the developer including undeveloped toner on the main sleeve roller is adsorbed by the sub sleeve roller, scraped off by the blade, and recharged by the stirring roller. As a result, toner having a uniform charge is always supplied to the main sleeve roller surface, density unevenness can be prevented even when various sizes of paper are used, and stable print quality can be secured. That is, it is possible to provide an excellent developing device which has never been obtained.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing a conventional example.

[Explanation of symbols]

 1 Developing Device 2 Stirring Roller 3, 10 Fixed Magnet 4 Stainless Cylinder 5 Main Sleeve Roller 6 Control Plate 7 Photosensitive Drum 8 Primary Charger 9 Semiconductor Laser 11 Sub Sleeve Roller 12 Blade

Claims (1)

[Claims] 1. A developing device of a printing apparatus using an electrophotographic system, comprising: a sub-sleeve roller for adsorbing the developer of the main sleeve roller; and a blade for scraping off the developer of the sub-sleeve roller. vessel.