JPS5810748B2 - Genzo Sochi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic developing device, and more particularly to a developing device with a favorable structure that does not adversely affect the surface to be developed when it is not in operation.

For practical purposes, it is desirable that the magnetic roller of the developing device adhere developer powder only during development and rub the photoreceptor for development, so that the developer powder does not come into contact with the photoreceptor outside the plate during development. .

Further, when developing multiple colors, different color developers are used, so if the developer of another color comes into contact with the surface to be developed while developing one color, this will cause color mixing, which must be absolutely prevented.

Conventionally, as shown in FIG. 1, a developer scraping member 2 is brought into contact with a magnetic roller 1, and rotates in the direction of arrow A during development to apply the developer to the surface to be developed. It rotates in the direction shown B so that the surface from which the magnetic brush has been removed is directed toward the surface to be developed.

In other words, in such a configuration, when rotating in the direction of arrow A, the intersection angle between the two surfaces of the scraping plate and the corresponding contact surface of the magnetic roller 1 is an obtuse angle θ.
A, the developer can be easily scraped off.

However, when rotating in the direction of arrow B, the intersecting angle forms an acute angle θB, so the developer is press-fitted into the portion and the frictional force is increased, which is undesirable as it imposes an abnormal load on the drive source.

Also, when rotating in the A direction, the developer that had already adhered to the scraping plate re-attaches to the scraping surface of the magnetic roller when the rotation is reversed.
There is a risk that the scraping plate will be transported, and there is also a possibility that the scraping plate will float due to the frictional pressure and pass through the contact area, resulting in no scraping effect.

Furthermore, the structure for operating the scraping plate requires a mechanism for mechanically or electrically bringing it into contact and separating it, which requires a corresponding number of control parts.

The present invention has been made in view of the above points, and an object of the present invention is to provide a new and excellent developing device.

That is, the present invention provides a developing device having a magnetic roller that holds a developer and supplies the developer to a surface to be developed. a scraping member that supports a portion of the scraper so as to be movable toward and away from the magnetic roller, the scraping member being at a first position away from the magnetic roller so that during development, the member is lifted by the developer and the developer passes under the member; and a scraping member that assumes a second position where it comes into contact with the magnetic roller so that the developer is pushed toward the magnetic roller side and scrapes off the developer when not developing. .

The term "magnetic roller" used in the present invention is not limited to magnetic rollers using bar-shaped magnets, but also includes sleeve-type rollers in which a magnetic source is provided within a non-magnetic cylinder.

Further, the developer is not limited to a developer using simply non-magnetic toner attached to a magnetic carrier, but it goes without saying that a developer using magnetic toner can also be used.

The details of the present invention will be explained below using specific examples with reference to the drawings.

FIG. 2 illustrates the configuration of an apparatus according to an embodiment of the present invention, in which the scraping plate 2 has an end C that is pivoted and fixed to the casing, and the other end is movable.

4 is a sealing material (for example, polyethylene) that seals the opening between the cover 3 and the scraping plate. The scraping plate 2 is in light contact with the magnetic roller 1, and the angle between the surfaces is <O.
The structure is such that DC satisfies <ODC≧90°.

When this rotates in the forward rotation direction (direction A) during development,
The developer powder adhering to the magnetic roller passes under the scraping plate 2 while lifting the surface of the scraping plate.

Next, when the magnetic drum rotates in the opposite direction (direction B), the frictional resistance between the developer powder and the D end causes a force to bite into the surface of the scraping plate, causing the developer powder to move from the D end of the scraping plate to the magnetic roller 1. As a result, the developer powder is scraped off from the magnetic roller 1, and the developer powder does not adhere to the magnetic roller 1.

Further, the same effect can be obtained by using an elastic body such as a synthetic resin sheet such as rubber or plastic as the material of the scraping plate.

At this time, as shown in Fig. 3, the C end of the scraping plate 2 is at the second
Since it can be fixed without being movable as in the illustrated embodiment, it is effective because the C end of the scraping plate does not become clogged with developer and cause instability in mechanical operation.

Further, if such a drop plate is placed near the area where the surface to be developed and the developer come into contact, it is extremely effective because it can be brought into a non-operating state in a short period of time.

FIG. 4 shows an example in which the developing device according to the present invention is applied to a monochrome electrophotographic copying device for black and white copying, and FIG. 5 shows an example in which the developing device based on the present invention is applied to a multicolor electrophotographic copying device for color copying. It is something.

In the figure, reference numeral 5 denotes a developing device which uniformly charges the photosensitive drum 6 with a charger 7 and develops an electrostatic image formed by exposure with an optical system 8.

The developing device receives the transfer material P supplied from the transfer material supply cassette 9.
The photosensitive drum 6 is transferred onto the photosensitive drum 6 using a corona transfer 10 or the like and fixed by a fixing device 11 to provide a copy, while the surface of the photosensitive drum 6 is cleaned by a cleaning means 12 and used for blue printing.

On the other hand, in multicolor reproduction, as shown in Figure 5, color separation means 8A
To form a latent image for each color and superimpose the developed color images, a transfer drum 13 is provided, and after the transfer paper is held on the drum and transferred a predetermined number of times, the separating claw 14 operates to separate the color images. A copy shall be provided.

Particularly in such a multicolor electrophotographic copying apparatus, it is important that the photoreceptor is not affected by the inactive developing device, and it is clear that the above configuration is extremely effective.

As described in detail above, the device of the present invention performs the developing operation without overloading the developer conveyance member such as a magnetic roller, and efficiently removes the developer on the surface of the conveyor body in a short time when the device is not in operation. Since it is scraped off and removed and does not affect the photoreceptor,
It is extremely effective.

Furthermore, since the scraping member operates in the direction of movement of the carrier, no extra control elements are required and the structure is extremely simple, which is effective in terms of manufacturing and maintenance.

[Brief explanation of drawings]

FIG. 1 illustrates a conventional developing device. FIG. 2 illustrates a configuration based on the present invention, and FIG. 3 illustrates a modified example. FIG. 4 shows a monochrome electrophotographic copying machine, and FIG. 5 shows a multicolor electrophotographic copying machine in which the present invention is applied. In the figure, 1 is a magnetic roller, 2 is a scraping plate, 3 is a cover, and 4
is a sealing material.

Claims (1)

[Claims] 1. In a developing device having a magnetic roller that holds a developer and supplies the developer to a surface to be developed, the magnetic roller has a magnetic roller whose moving direction is reversed during development and non-development, and an end portion on the side of the magnetic roller that is connected to the magnetic roller. a scraping member supported so as to be movable towards and away from the magnetic roller, the scraping member being supported at a first position away from the magnetic roller so that the member is lifted by the developer during development and the developer passes under the member; A developing device comprising: a scraping member that is sometimes pushed toward the magnetic roller by the developer and assumes a second position in contact with the magnetic roller so as to scrape off the developer.