JPS58163969A - Dry type developing device - Google Patents

Abstract

PURPOSE:To prevent toner fine powder from scattering to the outside from a gap of the lower end part of a casing, by providing a sealing member having elasticity, on the lower end part of the casing of a developing device, so as to contact with a toner on a developing sleeve. CONSTITUTION:A brush 16 being a sealing member having elasticity is provided on a lower end part 7a of a casing 7 so as to contact with a toner on a developing sleeve 5a. The brush 16 consists of a soft acrylic fiber, and is provided extending over the lengthwise direction of the sleeve 5a. On a developing roll 5, a tuft Q of the toner is formed, but it is sealed so as to catch the greater part of a toner cloud accompanied with the tuft, by the brush 16. Therefore, it is prevented that toner fine powder scatters to the outside from the gap, an exposure lamp 15 of the lower part and a transfer charger are prevented from its contamination, and an abnormal image quality in the lengthwise direction is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dry developing device used in Shigeko photographic devices and the like.

FIG. 1 shows a conventional dry developing device. Reference numeral 1 indicates a photoreceptor drum, which is rotated in the direction of the arrow during multi-gearing. It is provided facing the photosensitive drum 1 at a position on the rotational direction of the circumferential surface of the photosensitive drum 1, behind the charging charger 2, and between the exposure section 15 and the transfer section where the transfer charger 5 is disposed. There is a dry developing device 4. To briefly explain its structure, a developing roller 5 is disposed facing the photosensitive drum 1. The developing roller 5 is oriented such that the opposing portion thereof moves in the same direction as the photosensitive drum 1;
In other words, the cylindrical developing sleeve 5a rotates in the direction of the arrow.
It is composed of a group of magnets 5b, etc., which are immovably provided inside the developing Nureve 5a.

This magnet group 5b, as shown enlarged in FIG.
a main pole 5b1 that is disposed facing the development area and contributes to development by raising spikes of toner in the development area;
It consists of four commutative poles which are stationary and spaced apart from each other on an imaginary circle passing through b, and which convey toner.

These counterpoles are indicated by reference numerals 5b2.5b3.5b4°5b and 5 in the order of rotational direction of the developing sleeve 5B.

Furthermore, a pumping roller 6 as a toner supplying means is provided opposite the developing roller 5.

The pumping roller 6 has a large number of radial blades, draws toner between these blades, and supplies the toner to the developing roller 5 as it rotates in the direction of the arrow.

The developing roller 5 and the pumping roller 6 are covered by a casing 7 that is open at a portion facing the photosensitive drum 1. An opening is also formed on the casing 7 at the upper right part of the pumping roller 6, and a replenishment tank 8 is connected to this opening.
The pumping roller 6 is pumped up from the supply tank 8 according to the rotation of a.
Toner T is poured into the container.

Note that the toner T is replenished into the replenishment tank 8 through a toner hopper 9, and the toner T in the replenishment tank B is constantly agitated by the agitator 1o.

In the casing Z, the toner T supplied to the developing sleeve 5aK from the pick-up roller 6 receives the magnetic attraction force of the magnet group 5b to form a magnetic brush, and this magnetic brush rotates as the developing sleeve 5a rotates. They are sequentially moved toward the photosensitive drum 1.

During this process, the toner on the developing sleeve 5a is removed by the blade 1.
1, the height of the panicle is adjusted, and then it is subjected to development.

Reference numeral 12 indicates a separator that controls the flow of toner within the casing 7.

The exposure section 15 is located between the dry developing device 4 and the charging charger 2, and is irradiated with a light image of the document via the exposure optical system 14 etc., and the electrostatic latent image formed at this time is exposed to the dry developing device 4. The device 4 visualizes it as a toner image. On the way, this toner image is irradiated with light by the pre-transfer exposure rung 15 and is weakened to a suitable level without changing the adsorption force with the photoreceptor drum 1. After that, while passing through the transfer charger 5 section, the toner image is Transferred to transfer paper.

By the way, the prior art described in Section 2 has the following drawbacks.

In other words, from the consideration that the developed toner image should not be disturbed between the lower end 7a of the casing 7, which forms an opening facing the photoreceptor drum 1, and the photoreceptor drum 1, A gap is provided.

Fine particles of toner leak and scatter through this gap h and fall on a part of the pre-transfer exposure rung 15. As a result, the pre-transfer exposure lamp 15, which has a length in the longitudinal direction of the axis of the developing roller 5, becomes dirty, and the amount of light irradiated from the exposure rung 15 changes. As a result, an appropriate level of transfer cannot be maintained, resulting in abnormal image quality. Furthermore, the above-mentioned fallen toner also falls and adheres to the transfer charger and transfer paper guide (not shown) disposed in the transfer section, causing the charger's action to become unbalanced in its longitudinal direction. It also adheres to the paper and stains the transfer paper.

The present invention has been made in view of the above-mentioned problems in the prior art, and it is an object of the present invention to provide a dry type developing device that can prevent fine toner powder from scattering to the outside from the gap at the lower end of the casing.

The present invention will be explained in detail below.

The dry-type developing device according to the present invention includes an area on the developing sleeve from a region where the main pole faces to a region where the complementary pole adjacent to the main pole faces in the rotational direction of the developing sleeve. A brush is provided in the same manner at the lower end of the casing, which is the proximal end thereof, so as to be in contact with the developing sleeve or the toner on the developing sleeve at any position on the shaft in the longitudinal direction. do.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As an example of the sealing member according to the present invention, a brush is shown at 16 in FIG. The brush 16 is disposed on the developing sleeve 5a at a position facing the supplementary member 4t5b, facing forward in the direction of rotation of the developing sleeve 5a, so as to come into contact with the developing sleeve or the toner on the developing sleeve. In addition, the base end portion is provided in the same manner as the lower end portion 7a of the casing 7. This brush 16 is provided over the axial longitudinal direction of the developing sleeve 5a, and has a wire diameter of approximately 100 μm1.
The length of the long part is approximately 7M, the density of flocking is 20,000 to 50,000 per square inch, and soft fibers such as acrylic fibers are used.

The reason why the brush 16 is provided at the second position is that since toner ridges Q occur on the developing roller 5 corresponding to the commutative electrode 5b2, the brush 16 is designed to be sealed at a position in front of the ridges Q. In other words, the brush 16 captures and seals most of the toner cloud that accompanies the above-mentioned spikes and scatters outward from the lower end of the casing. For example, the toner on the developing sleeve 5a is attracted to the developing sleeve 5a by the magnetic field of the main pole 5b. In the development area, the ears of the magnetic brush stand up and are used for development in that state, but at an intermediate position between the main pole 5b and the complementary pole 5b2, the ears fall down. Then, when it enters a region where the magnetic field of the copole 5b2 acts strongly, the ears will rise again. As mentioned above, when the spikes stand, the toner at the tip becomes easily separated, and some of it separates and scatters, falling through the gap at the lower end of the casing, resulting in the above-mentioned prior art. This was causing the problem.

The brush 16 as an example of the seal member according to the present invention is
To capture the toner that is in light contact with the toner in a state where the ears have fallen down and that has separated from the tip of the ear or is about to separate. In other words, if the brush 16 is arranged so as to be in contact with the developing sleeve 5a very close to the commutative pole 5b2, it is possible to capture the toner just before or after the separation due to blistering occurs, and the main pole 5b, When the developing sleeve 5aK is arranged so as to be in contact with the developing sleeve 5aK, it functions as a seal to trap the separated and scattered toner to prevent it from coming out.
As the brush 11 continues to be used, the toner captured by the brush 16 will gradually accumulate, and there is a concern that the toner will accumulate. No problem arises with this selection. Furthermore, if a material similar to the charging series of the toner to be used is used as the brush material, it is more effective to prevent toner from accumulating since it is difficult for an electric attraction force to act between the toner and the brush.

In the experimental results, good results were obtained with the brush 16, but it is thought that a similar sealing effect can be obtained by using a weak film-like elastic material as the sealing member instead of the brush 16.

In addition, considering the leakage of toner from the entire developing device, it is necessary to take into account not only the lower end of the casing but also the upper end 7b of the casing. However, the generation of toner cloud does not only occur on the developing roller 5 corresponding to the commutative electrode 5b2, but also on the developing roller 5 corresponding to the commutative electrode 5b5, for example.
This is because it occurs due to the spikes K on the developing roller 5 corresponding to the above, and also due to the impact when the toner T collides with the photoreceptor drum 1 at the entrance of the developing area.

There is a possibility that the toner cloud leaks out from the gap between the upper end 7b of the casing 7 and the photoreceptor drum 1 and contaminates the inside of the apparatus, especially the optical system. Therefore, as a countermeasure, if the inlet sealing member 20 is provided so that the base end is fixed to the upper end 7b and the free end is in contact with the circumferential surface of the photoreceptor drum 10, the sealing of the developing device will be more complete. It can be made close. This sealing member 20 is made of an insulating material so as not to disturb the electrostatic latent image on the photoreceptor drum 1, and a material that is not easily charged by frictional contact with the photoreceptor drum 1 is selected. There is a need. For example, regarding insulation, photoreceptor drums 1 and 60
It is preferable to use a film-like or brush-like member that exhibits a resistance value of io9Ω or more when contacted with a width of 0B. Specifically, for example, a brush made of Teflon (trade name) and having a structure similar to the brush 16 described above is used.

Alternatively, when using a two-component toner, the upper end Zb
It is also conceivable that a magnet is disposed in the inlet sole member 20 so that the toner carrier is attracted to the magnet.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of a dry developing device according to the prior art;
FIG. 2 is a block diagram of the main parts of the dry developing device according to the present invention. 5a...Developing sleeve, 5b1...Main pole, 5b2...
...Brush (as an example of a sealing member). -11-

Claims (1)

[Scope of Claims] A main pole immovably disposed facing the photoreceptor drum in a developing area formed around the photoreceptor drum at an intermediate position between the exposure section and the transfer section; A plurality of commutative poles are arranged on an imaginary circle passing through this main pole at intervals from the main pole, and a part that covers the periphery of each of these magnets and faces the photoreceptor drum is a part of the photoreceptor drum. A developing roller whose main component is a developing sleeve configured to rotate in the same direction as the moving direction, a toner supply means for supplying toner to the developing roller, and an opposing S to the photoreceptor drum. In a dry type developing device having a casing having an opening and covering the developing roller, toner supply means, etc., from a portion on the developing sleeve where the main pole faces, in the rotational direction of the developing sleeve, Contact the developing sleeve or the toner on the developing sleeve in the longitudinal direction of the axis at any position on the region where the complementary pole adjacent to the main pole faces, and the proximal end thereof 1. A dry type developing device comprising an elastic sealing member disposed in the same manner at a lower end of a casing.