JPH0462582B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a developing device, and particularly to a developing device that can be miniaturized as a whole.

[Prior art]

Generally, a developing device provided in an image forming apparatus such as an electrophotographic copying machine is constructed as shown in FIG.

That is, the developing device 2 is disposed near the photosensitive drum 1, which is an image carrier, and has a casing 4 forming a developer storage section 3 in which developer is stored in the lower part. A stirring member 5 rotated by a drive member (not shown) is disposed within the agent storage portion 3 .

Above the stirring member 5 and closer to the photoreceptor drum 1, a developing sleeve 6 made of a non-magnetic material such as aluminum and rotating in the direction of the arrow is connected to the circumferential surface of the developing sleeve 6 and to the photoreceptor drum 1. The developing sleeve 6 includes a magnetic body 7 having a plurality of N and S magnetic poles alternately arranged in the circumferential direction on its surface.
is arranged so as to be rotatable in the direction of the arrow.

The N and S magnetic poles of the magnet 7 are usually 500
It is magnetized to a magnetic flux density of ~1500 Gauss.

A regulating blade 8 is provided on the front side of the developing sleeve 6 in the rotational direction with respect to the photosensitive drum 1, and is spaced from the outer peripheral surface of the developing sleeve 6 by a predetermined distance.
The predetermined interval can be changed depending on the type of developer used (one-component developer or two-component developer).

Furthermore, a scraper 9 that is in contact with the outer circumferential surface of the developing sleeve 6 is disposed further forward in the rotational direction of the developing sleeve 6 than the developing area A.

A hopper 10 for toner particles T is provided in the upper part of the casing 4, and a supply roller 11 having a concave portion on its surface is provided at the lower opening of the hopper 10 to drop the toner particles T into the developer reservoir 3. is provided.

Note that 12 is a bias power source that applies a bias voltage to the developing sleeve 6 through a protective resistor 13, which is direct current, alternating current, or a combination of direct current and alternating current.

In the developing device 2 configured as described above, a so-called spike of developer is formed on the surface by the magnet in the developing sleeve 6, and this is supplied to the photoreceptor drum 1. , which develops the electrostatic latent image on the surface of the photoreceptor drum 1, but due to the magnetic force distribution of the magnet disposed inside, both ends of the developing sleeve 6 are not magnetized vertically. , because there is not enough developer attached compared to the central part which is properly magnetized vertically.
Therefore, a rubber blade 15 is used to scrape off the developer adhering to both ends (portions that do not affect the electrostatic latent image corresponding to the image), thereby causing stains on the transfer paper. It was preventing this.

However, since the developing device 2 configured as described above uses the rubber blade 15 as described above, it is attached via a fixing member in consideration of the hardness of the rubber. In addition, since the rubber contains various reinforcing agents, contact with the circumferential surface of the developing sleeve 6 causes wear and stains.

[Purpose of the invention]

This invention eliminates the drawbacks of the conventional ones as described above, and develops by constructing blades made of polyethylene terephthalate (PET), which are disposed at both ends of the developing sleeve to remove unnecessary developer. It is an object of the present invention to provide a developing device that can reduce the size of the entire device and can also prevent stains from being generated due to wear.

[Structure of the invention]

In this invention, a magnet body in which different magnetic poles are alternately formed in the circumferential direction of the surface is disposed inside, and
The developing sleeve, which rotates relative to the magnet and adheres the developer to its surface, is in contact with the developing sleeve at both ends in the axial direction and at a position facing a portion outward from the width of the paper. The blade is made of polyethylene terephthalate and removes the developer.

[Embodiments of the invention]

Embodiments of the invention shown in the drawings will be described below.

FIG. 1 shows a schematic layout of a developing device according to the present invention, and the same members as those in the conventional device are given the same numbers and their explanations will be omitted.

First, when the developing device 2 is started, the stirring member 5 starts rotating, and the developing sleeve 6 and the magnet body 7 each start rotating in the direction of the arrow.

As a result, a part of the developer D in the developer reservoir 3 moves upward by the magnetic force of the magnet 7 and reaches the regulating blade 8, which is a magnetic member, and the amount passing therethrough is regulated. At the same time, since it is magnetized by the magnet body 7 as described above, ears of developer D, that is, magnetic brushes, are formed on the surface of the developing sleeve 6 by its magnetic force at a predetermined height and amount.

Then, as the developing sleeve 6 rotates, the magnetic brush reaches the developing area A with the image carrier 1, and development is performed with or without contact.

The magnetic brush after development that has passed through the development area A rotates together with the development sleeve 6 and reaches the scraper 9, where it is scraped off from the development sleeve 6 and falls into the developer reservoir 3, and in this way, the development is performed one by one. Development is performed in area A, and the developer after development falls into the developer reservoir 3 by the scraper 9 and is stirred by the stirring member 5 within the developer reservoir 3, so that the developer supplied to the development area A is The ingredients of the agent are always homogenized,
Therefore, high developing performance can always be maintained.

2 and 3 show the main parts of the developing device according to the present invention, in which the N and S poles of the magnetic body 7 are successively opposed to the surface portion of the photosensitive drum 1 corresponding to the paper width. A uniform magnetic force is distributed over a portion of the surface of the photosensitive drum 1 corresponding to the width of the paper, thereby making it possible to form uniform spikes of developer.

However, since the outer portions of the N and S poles of the magnet are not completely magnetized vertically, the ears are attached in a sequentially lowered state (Fig. 2).
A blade 1 whose rear end is attached to a casing 4 is located on both sides of the part that is no longer magnetized completely vertically by the magnet, that is, the part facing the paper width.
The tips of the developer spikes 5 are pressed against each other, thereby removing unnecessary end portions of the spikes of developer so that they are present only in the portion corresponding to the width of the paper as shown in FIG.

In this case, since the material of the blade 15 is polyethylene terephthalate, the blade itself has a certain degree of strength, and unlike conventional rubber, no reinforcing agent is mixed in, so it can be easily attached to the casing. There is no need to use a special attachment member, and even if the developing sleeve 6 is worn out by rotation, that is, by use, this abrasion powder will not become dirt.

〔Effect of the invention〕

By configuring this invention as described above,
Not only can spikes of developer be formed only in the area facing the width of the paper, but other unnecessary developer can be removed to prevent unnecessary dirt from adhering to the paper, and the blade is made of polyethylene terephthalate. As a result, it can be installed without the need for any special mounting parts, and since there is no reinforcing agent mixed in compared to when it is made of rubber, wear particles will not get dirty even if it is worn out through use. Therefore, it has excellent effects such as there is no risk of it getting mixed into the developer and staining the image.

[Brief explanation of drawings]

FIG. 1 is a schematic layout diagram showing a developing device according to the present invention, FIGS. 2 and 3 are schematic explanatory diagrams showing the relationship among a photosensitive drum, a developing sleeve, a magnet, etc., and FIG. 4 is a schematic diagram showing a conventional developing device. It is a layout diagram. 1...Photosensitive drum, 2...Developing device, 3...
Developer reservoir, 4...Casing, 5...Stirring member, 6...Developing sleeve, 7...Magnet, 8...
Regulation blade, 9... Scraper, 10... Hopper, 11... Supply roller, 12... Bias power supply, 13... Protection resistor, 15... Blade.

Claims (1)

[Claims] 1 A developing sleeve in which a magnet body in which different magnetic poles are alternately formed in the circumferential direction of the surface thereof is disposed, and a developing sleeve that rotates relative to the magnet body to attach a developer to the surface, and a developing sleeve in the axial direction of the developing sleeve 1. A developing device comprising blades made of polyethylene terephthalate that come into contact with positions at both ends facing the outside of the paper width to remove unnecessary developer.