JPS5986072A - Developing device - Google Patents

Abstract

PURPOSE:To reduce a developer in weight pressure by providing a pressure preventing member at the upstream side of a backward developer flow by a developer thickness specifying member. CONSTITUTION:The thickness of a toner thin layer formed on the sleeve 3 of a developer supporting member is made uniform by the blade 6 of a developer member. Further, the pressure preventing member 7 is provided in contacting with the blade 6 and closely to the sleeve 3 where an inversion part (b) and a backward flow (c) of toner formed by the blade 6 are not impeded, and the weight pressure of the toner on the preventing member 7 does not extend to below the preventing member 7, thereby reducing the toner weight pressure. Consequently, the crosslinking of toner, flocculation of toner near the blade 6, etc., are prevented to form an invariably uniform thin layer of toner on the sleeve 3, attaining the formation of a picture of good quality.

Description

Detailed Description of the Invention The present invention is applied to an image forming apparatus such as an electrophotographic copying machine, an electrostatic recorder, a magnetic recorder, etc., and is a developing device that develops a latent image on the surface of a latent image carrier into a visible image. In particular, the present invention relates to a developing device in which developer supplied on a developer supporting member is regulated to be uniform and thin by a developer regulating member while being conveyed to a developing position facing a surface of a latent image carrier.

Figure 1 shows the schematic configuration of this type of developing device.
6 is a hopper as a storage device for the developer 2 (hereinafter referred to as toner), and 6 is a cylindrical non-magnetic sleeve (hereinafter referred to as sleeve) rotatably supported in the hopper 1. A portion of the opening 1a of the hopper 1 extends over the entire length in the longitudinal direction.
The photoreceptor 4 is exposed to the outside and is opposed to the photoreceptor 4, which serves as a latent image carrier, with a gap therebetween. Reference numeral 5 denotes a magnet roller which is fixedly arranged concentrically within the sleeve and has a plurality of magnetic field generating magnetic poles N@S on its 9 circumferential surface. Relative rotational movement between the magnetic field and the sleeve due to the rotation of the sleeve A in the direction shown (
As shown in Figure 2, the toner is restrained by the supporting force of the magnetic field on the sleeve surface and moves in the same direction as the rotation direction of the sleeve. using sleeve 6
When fixing the magnetic roller 5 and rotating the magnetic roller 5.

The direction of movement of the toner is opposite to the direction of rotation of the magnetic roller. (See Japanese Patent Publication No. 37-14798).

The toner moving while being restrained by the sleeve surface is regulated into a uniform thin layer by a toner regulating unit (hereinafter referred to as a blade) 6, and then transported to a developing position where the sleeve 6 and the photoreceptor 4 approach each other. and then subjected to development. On the other hand, the toner whose progress is blocked by blade B is pushed by the advancing force of the following toner.

After proceeding in the direction indicated by the arrow along the blade O, it changes direction due to its own weight and proceeds in the direction indicated by the arrow C, which is opposite to the above.

The hopper 1 in this developing device is usually in the shape of a trumpet that gradually expands from the mounting part of the sleeve B toward the road, so that the weight pressure P1 of the stored toner 2 is exerted on the sleeve as shown in FIG. become. If the hopper 1 is made smaller, the pressure P1 exerted on the sleeve by its own weight can be reduced, but at the same time, the number of toner replenishment increases. Therefore, the hopper should be of a certain size for peace of mind, but as a result, disadvantages arise.

(1) Due to the pressing force due to the weight of a large amount of toner, crosslinking and blocking tend to occur in the lower part of the hopper, making it impossible to supply an appropriate amount of toner to the photosensitive drum.

(2) When aggregated toner produced by blocking or crosslinking is supplied to the developing roller, there is a drawback that uneven development, fogging, etc. occur.

(3) When regulating a single layer of toner formed on the sleeve with a blade, the aggregated toner remains on the blade and scratches the toner layer, resulting in linear mold in addition to normal fogging. .

In some cases, the aggregated toner may harden further and scratch the surface of the photosensitive drum, significantly shortening its life.

The present invention aims to eliminate the drawbacks of the above-mentioned conventional devices, and has a simple structure that reduces the pressure of the toner's own weight on the sleeve, stably forms a uniform thin layer of toner on the sleeve, and produces high-quality toner. An object of the present invention is to provide a developing device capable of obtaining a visible image.

As a means for achieving the above-mentioned object, the present invention provides developer support above a reversal phenomenon in which the developer flow C is blocked by the developer regulating member 6 and reversed to advance in the opposite direction, as shown in Figure J4. The present invention is characterized in that a pressure prevention member 7 is provided to prevent the self-weight pressure of the developer 2 from acting on the member 6.

With this configuration, as shown in FIG. 5, the pressure P3 of the toner on the pressure prevention member 7 is received by the pressure prevention member, so that the pressing force P2 of the toner on the sleeve is applied to the sleeve 1 and the pressure prevention member 7. This is only due to the toner in between. Therefore.

PI = P2 + P3, PI >> P2, and the pressure on the sleeve 1 is reduced.

Note that the position of the pressure prevention member 7 is extremely important, and the following points must be kept in mind.

a)) Do not obstruct the nine-turn movement of the nut 2 in the direction of arrow b-C.

b) In order to improve the pressure prevention effect, the pressure prevention member 7 needs to be placed close to the developer support member within a range that does not obstruct the progress of the toner flow.

If the pressure prevention member 7 is brought close to the sleeve 1 at a position 1 that obstructs the rotational movement of the toner in the arrow b-c direction, pressure due to the sliding of the toner 2 will be applied to the sleeve surface, causing bridging and blocking. Toner easily adheres to the sleeve, resulting in uneven images even when developed, and the provision of the pressure prevention member 7 becomes meaningless. On the other hand, if the pressure prevention member is placed far away from the sleeve 6, the effect of preventing the toner's own weight pressure acting on the sleeve will be reduced. Therefore,
Position of the pressure prevention member 1. It is preferable to place the pressure prevention member at a position as close as possible to the sleeve outside the movement path of the Hutner in the directions indicated by arrows B and C.
0 rhyme) is good. The oblique angle 01 of the pressure prevention member with respect to the horizontal plane is preferably greater than or equal to the angle of repose of the developer. If the angle of inclination 01 is less than or equal to the angle of repose 02, the developer in that area cannot be transferred and the developer does not contribute to development at all. This is because it causes

FIG. 6 is a side view showing a first embodiment in which the dry developing device 1 of the present invention is applied to a copying machine using a drum-type photoreceptor.
The same parts as those in the first and third IyJ are given the same reference numerals, and the description thereof will be omitted. Around the photoreceptor 4 in my example, there is a charging mechanism (not shown), an image exposure mechanism, and a transfer mechanism (not shown).

A cleaning mechanism, a TJ removal mechanism, and a mechanism are provided.

It is assumed that continuous copying was performed using a commercially available one-component magnetic toner (toner for Canon NP-120).
Clear, high-quality images with no image unevenness were obtained on more than one sheet. As a comparative example, when continuous copying was performed using the same toner with a conventional apparatus having the same configuration as the present example except that no pressure and prevention member was used, white streaks appeared on the image after 5,000 copies were made.

The rotational movement of the toner depends on the properties of the toner itself (electrical resistance, particle size distribution, magnetic permeability, etc.), the properties of the sleeve (material,
The angle of inclination θ of the blade with respect to the horizontal plane, etc. determines the appropriate placement location of the pressure prevention member. In the above example, the inclination angle θ of the blade B is about 70°, but if the inclination angle θ is set to 110.90° as shown in FIG. Move up to. Therefore, the arrangement shape of the pressure prevention member 7 changes depending on the movement form of the toner.

As described above, in the present invention, since the pressure preventing member is provided above the reversed toner flow which is blocked by the blade and reversed to proceed in the opposite direction, the toner is applied to the sleeve H without any obstruction to the progress of the toner flow. Self-weight pressure can be reduced. the result.

Blocking and crosslinking of the toner, and aggregated toner stagnation in the blade section are eliminated, and the toner stably adheres to the sleeve in a uniform thin layer, making it possible to obtain a clear, high-quality developed image with no unevenness.

The sleeve may be either magnetic or non-magnetic.The toner may be magnetic toner, which is supported and conveyed onto the sleeve by the magnetic field of a magnet roller, as shown in the example.
A peeping toner may also be used.

[Brief explanation of drawings]

The first quotient is a side view showing an outline of a conventional developing device. FIG. 2 is a diagram showing the movement of toner on the sleeve in the above-mentioned developing device, FIG. 6 is a diagram of the action of the toner's own weight on the sleeve, and FIG. 4 is a diagram showing the movement of toner on the sleeve showing the main parts of the developing device of the present invention. FIG. 5 is a state diagram showing the action of the toner's own weight on the sleeve. FIG. 6 shows an outline of an embodiment of the developing device of the present invention.
FIG. 7 is a front view, FIG. 7 is a side view of a main part showing an eighth modification resistant example. 1 is a hopper, 2 is a toner, 6 is a sleeve, 4 is a photoreceptor,
5 is a magnet roller, 6 is a flap. 7 is a pressure prevention member 0

Claims (1)

[Claims] (1) In a developing device in which the developer supplied on the developer supporting member is regulated into a uniform thin layer by a developer regulating member while being conveyed to a developing position facing the latent image carrier, the developer regulating member A developing device characterized in that a pressure preventing member is provided above the reversed developer flow which is prevented from advancing and reversed and advances in the opposite direction, for preventing the dead weight pressure of the developer acting on the developer supporting member. Device.