JPS6022361Y2 - developing device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a developing device for an electrophotographic or electrostatic recording device.

Generally, when magnetic particles are used as a developer carrier, a magnetic brush is applied by magnetic means to develop an electrostatic latent image on a photosensitive plate, or a fur brush is used to develop the latent image.

The developed and visualized toner image is transferred to a transfer material such as paper and then heated and fixed to complete a copy image.

The mixing ratio of the carrier and toner constituting the developer is an extremely important factor in determining the density of the copied image.

In other words, during development, the toner adhering to the magnetic brush or fur brush adheres to the electrostatic latent image by rubbing against the photoconductor, and the amount of toner in the developer gradually decreases, resulting in the density of the copied image being reduced. The result is a decline.

For this reason, the density of the copied image is stabilized by replenishing the developer with an appropriate amount of toner, but if the amount of toner replenished exceeds the appropriate amount, the density of the copied image will not become excessively high, and the copied image will become foggy. This may cause contamination around the developing device due to excessive toner scattering.

Therefore, a detection device is required to accurately detect changes in developer concentration and replenish an appropriate amount of toner.

Taking a conventional developer concentration detection device as an example, there is a method in which the surface of a magnetic brush is irradiated with brush light and a change in the developer concentration is detected by using a light receiving element such as CdS or the like to receive reflected light.

However, with this measurement method using a light source and a light receiving element, good results cannot be obtained due to diffuse reflection of light caused by the shape of the magnetic brush.

Furthermore, the scattering of the developer may contaminate the light source and the light receiving element, causing errors in the measurement results.

A conceivable way to solve the above problem is to block the light source and the light receiving element from the area where the developer is present with a light-transmitting member.

However, in this method, although the light source etc. are not contaminated, if the developer adheres to the transparent member and becomes unable to move,
Similarly, error movements will occur.

The purpose of the present invention is to eliminate the drawbacks of the detection device having a light source and a light receiving element for detecting changes in the developer as described above, and to make it possible to accurately detect the state of the developer. .

The present invention, which is distantly related to the above object, supplies developing powder onto a developing sleeve containing a magnet inside, forms a magnetic brush using the developing powder on the developing sleeve, and forms an electrostatic latent image with the magnetic brush. A magnetic brush developing device for visualization includes a light-transmitting member provided close to the surface of the developing sleeve, and a light source and a light-receiving element for optically detecting the developer through the light-transmitting member. be.

With the above configuration, the developer side surface of the light-transmitting member is constantly cleaned by the developer forcibly moved by the magnet in the developing sleeve.

Therefore, since there is no accumulation or contamination of the developer on the developer side of the transparent member, it is possible to accurately detect the developer using the light source and the light receiving element.

Next, the present invention shown in the drawings will be explained in detail with reference to examples.

FIG. 1 shows a developing device using a magnetic brush.

In this developing device, a developing sleeve 6 rotates around a fixed magnet portion 7 in the direction of the arrow.

A magnetic brush 8 is formed on the surface of the sleeve 6 using magnetized magnetic toner, and the tip of the brush 8 is scraped off with a scraper 5 to make the length of the brush uniform.

The electrostatic latent image on the photoreceptor 1 is developed by this magnetic brush 8 having a uniform length.

Note that the developer 3 is constantly stirred by a stirring roll 4 so that the carrier and toner are sufficiently mixed.

In the figure, 9 indicates a developing container.

An example in which the present invention is applied to the apparatus shown in FIG. 1 will be described below.

〔Example〕

FIG. 2 shows that a part of the magnetic brush 8 is pressed against the shape plate 15, and the flat part A of the magnetic brush 8 thus created is irradiated with light by the light source 11 in the detection device container 14. The concentration of the developer is detected by condensing the reflected light from A by a lens 12 and sending it to a light receiving element such as CaS.

Note that the flat plate 15 is a member made of a translucent material such as glass in order to measure the chromaticity of the developer from the outside.

As a result, if the surface to be measured is flat, there will be no diffuse reflection and the reflected light will be stable, and since the flat plate, which is a translucent material, is constantly being rubbed by the magnetic brush formed by the magnet in the sleeve 6. Toner does not adhere to the flat plate.

As a result, measurements were extremely stable and accurate.

The installation position of the detection device in this example is when the magnetic brush extending into the developing area of the photoconductor is extended parallel to the photoconductor, but in reality, the detection device is installed at the magnetic brush section where development is not being performed. It can be installed anywhere where the length of the tube is uneven.

Further, the distance between the flat plate 15 and the sleeve 6 varies depending on the strength of the magnetic field, but in this embodiment, it is approximately 5 to 7 wn.

As explained above, according to the developer detection device provided by the present invention, there is a light source and a light receiving element for detection on the outside of the developer container sealed with a light-transmitting member.

There is no possibility of developer scattering to contaminate these detection components, and therefore, measurement errors due to developer scattering do not occur.

Furthermore, the inner surface of the translucent member that seals the developer container is constantly rubbed by the developer that is forcibly conveyed by magnetism.

This prevents the developer in the developer container from adhering to the light-transmitting member and blocking the optical path or remaining therein, even without using a special mechanism for cleaning and stirring the inside of the developer container.

Therefore, the detection function of the light source and the light receiving element can be determined more accurately, and the defects can be eliminated.

[Brief explanation of the drawing]

Figure 1 shows a developing device of an electrophotographic device using a magnetic brush.
FIG. 2 is an optical detection device that is an embodiment of the present invention. In the figure, 1...photoreceptor, 2...developing device, 3...developer, 7...fixed magnet section, 8... - Magnetic brush, 10... Optical detection device, 15... Translucent flat plate.

Claims (1)

[Claim for Utility Model Registration] Developing powder is supplied onto a developing sleeve containing a magnet inside, a magnetic brush is formed by the developing powder on the developing sleeve, and the electrostatic latent image is visualized by the magnetic brush. A magnetic brush developing device, comprising: a light-transmitting member provided close to the surface of the developing sleeve; and a light source and a light-receiving element that optically detect developer through the light-transmitting member.