JPS59114560A - Dry type developing device - Google Patents

Abstract

PURPOSE:To uniformly and efficiently stir a developing agent by providing plual stirring members along the axial direction of a revolving shaft. CONSTITUTION:Below a hopper 4 gradually expanding upward in a cross section with an opening at the bottom to be a developing agent container, a developing sleeve 2 to be a developing agent carrier is provided to expose a part of the sleeve to the outside of the hopper 4 through the opening 4a. An agitator 10a installed in the hopper 4 is fitted with three stirring members 8a, 8b, and 8c formed by bending a bar-like material, such as wire, etc., to have a U-shape. The stirring members 8a, 8b, and 8c are spaced to fix to the revolving shaft. The sectional area of the stirring member made from the bar-like material is made as small as possible not to apply large load to the toner by the agitation with the stirring members. Moreover, a coil 9 is provided to the stirring members 8a and 8c at both ends as an auxiliary stirring member by extrapolating the coil partly to the least.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a developing device that performs development by applying a developer to an electrostatic latent image. The present invention relates to a developing device suitable for developing a latent image.

In a developing device using a conventional dry-component developer, a developing sleeve serving as a developer carrier is usually disposed below a developer storage container. Therefore, the toner is subjected to a downward load due to gravity, which tends to cause a decrease in the fluidity of the toner and the formation of toner aggregates. In order to prevent such a decrease in toner fluidity and the formation of toner aggregates, an agitator, which is a means for stirring the developer, is provided in the storage container to agitate the developer. Attempts to supply toner have been proposed.

However, the toner supplied onto the developing sleeve is
Since the toner layer thickness is regulated to a constant layer thickness by a doctor blade serving as a toner layer thickness regulating means and transported to the developing area, the toner is prevented from being transported by the developing sleeve by the doctor blade.

The doctor blade is pushed upward along the wall of the storage container in which the doctor blade is supported, and remains near the doctor blade. As the developing sleeve rotates, the amount of toner staying around the doctor blade increases, the density and pressure of the toner increases, and toner aggregates are formed. When toner aggregates are formed in this way, the circulation of toner within the container becomes poor, and the thickness of the toner layer on the circumferential surface of the developing sleeve becomes uneven, resulting in density unevenness, etc. in the resulting copied image. This occurs and causes a reduction in image quality.

On the other hand, a detailed study of the toner supply operation in the developing device shows that when toner is supplied from the storage container to the developing sleeve, it tends to be biased toward both ends of the sleeve compared to the center. This, together with the fact that the image formation rate is higher at the center than at both ends of the photoreceptor that carries the electrostatic latent image to be developed, means that the rotation of the developing sleeve causes the developing sleeve to The toner in the center moves more easily than the toner near both ends of the developing sleeve, and therefore the toner decreases more easily in the center than at both ends of the developing sleeve, causing an imbalance in the toner supply distribution on the circumferential surface of the developing sleeve. do.

This results in a decrease in the quality of the obtained image.

Purpose The present invention has been made in view of the above points, and is capable of preventing the formation of toner aggregates in a toner storage container, supplying high-quality toner onto the circumferential surface of a developing sleeve, and forming a uniform layer. It is an object of the present invention to provide a developing device capable of forming a single thick layer of toner and providing high image quality without uneven image density.

Configuration Hereinafter, specific embodiments of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is a block diagram showing the overall structure of a developing device according to a first embodiment of the present invention. FIG. 2 is a schematic diagram showing the configuration of the agitator 10a used in the developing device of FIG. 1. As shown in FIG. 1, below a hopper 4, which is a developer storage container, which has a shape that gradually expands upward and has an opening 4a at the bottom, a developing sleeve 2, which is a developer carrier, has a part of the opening 4a. It is exposed to the outside of the hopper 4 through the hopper 4. The developing sleeve 2 has a cylindrical shape and is driven and rotated in the direction indicated by the arrow. A magnet roll 3 is disposed inside the developing sleeve 2 as a suction means for sucking the toner 6 stored in the hopper 4 onto the circumferential surface of the developing sleeve 2. A photoreceptor 1 carrying an electrostatic latent image is disposed so as to be movable in the direction of arrow B, in close proximity to or in contact with the surface of the developing sleeve 2 exposed to the outside through the opening 4a of the hopper 4. There is. Further, a doctor tape 5 serving as a layer thickness regulating means for regulating the layer thickness of the toner 6 supplied onto the circumferential surface of the developing sleeve 2 to a predetermined value has its tip facing the circumferential surface of the developing sleeve 2, and It is supported by the hopper 4. Further, a rotating shaft 7 is provided in parallel with the developing sleeve 2, and extends within the hopper 4 so as to be driven and rotated in the direction of arrow C. Note that the rotational speed of the rotating shaft 7 is several r, p, m, to several tens of r, p, m,
It is best to set it to a value in the range of .

The agitator 10a provided in the hopper 4 includes three stirring members 8a, 8b, and 8c formed by bending a rod-shaped material such as a wire into a substantially U-shape, and fixing them to the rotating shaft 7 while separating them from each other. It is composed. Note that the cross-sectional area of the stirring member 8 made of a rod-like substance is preferably set as small as possible so as not to apply a large load to the toner due to stirring. As is clear from FIG. 2, there are also stirring members 8a at both ends.

8C is provided with a coil 9 as an auxiliary stirring member at least partially extrapolated. The coil 9 is loosely fitted to the stirring member 8 and is movable in the radial and axial directions. Incidentally, it is preferable to arrange the two coils 9a and 9C with their helical directions reversed. As described above, the stirring member 8 is fixed to the rotating shaft 7, and the stirring members 8a and 8c at both ends are provided with coil-shaped auxiliary coils and the stirring members 9a and 9c.
are provided so as to be freely movable, so that the stirring member 8 is rotated together with the rotation of the rotating shaft 7, but the coiled auxiliary stirring members 9a and 9c are configured to rotate almost without restraint. The rotating shaft 7 can be arranged so that the coiled auxiliary stirring member 9 can come into contact with the circumferential surface of the developing sleeve 2 when the agitator 10a rotates. Incidentally, since toner agglomeration is particularly likely to occur near the wall 4b of the hopper 4 that supports the doctor blade 5, it is preferable to set the agitator 10a so that it can agitate this area.

Next, the operation of the apparatus according to the embodiment of the present invention having such a configuration will be explained. Toner is supplied from above the hopper 4 and toner 6 is stored inside the hopper 4. The toner 6 in the center of the hopper 4 is agitated by rotation of the agitator 10a in the direction of arrow C. Compared to the prior art, this agitator 10a is divided into a plurality of pieces (three pieces in this embodiment) and is provided on the rotating shaft 7, so that a larger amount of developer can be stirred and a uniform and highly efficient stirring effect can be achieved. can get. Coiled auxiliary stirring member 9
As the agitator 10a is driven to rotate, it moves within the hopper 4 and, at the same time, does not come into contact with the toner 6 and rotates almost without restraint 9, thereby stirring the toner 6 with a small load. When such an auxiliary stirring member 9 is provided, the auxiliary stirring member 9 is attached to the developing sleeve 2. Drap V-do 5. It is possible to have a structure that allows contact with the hopper wall 4b, etc., and therefore allows stirring in a wider stirring range, and also prevents toner from accumulating in the vicinity of the doctor blade 5, where there is a particularly high risk of toner aggregation. This makes it possible to actively stir the area.

The toner 6 stirred by the coiled auxiliary stirring members provided on the stirring members 8a and 8c at both ends with the helical directions of the coils 9a and 9c reversed tends to be pushed out to the center of the developing sleeve 2. , the toner 6 is uniformly supplied to the entire circumferential surface of the developing sleeve 2. In this case, since the coiled auxiliary stirring member 9 is provided in the stirring member 8 so as to be freely movable and rotates without restraint, even if it is disposed so as to be able to contact the curved surface of the developing sleeve 2, it will not damage the circumferential surface of the developing sleeve 2. There's nothing to do. As described above, according to the present invention, the toner 6 in the hopper 4 is uniformly stirred without staying in the vicinity of the doctor blade 5, so that the toner 6 of good quality without agglomeration and having easy-flowing properties is produced. It is uniformly supplied onto the circumferential surface of the developing sleeve 2. Therefore, the toner on the developing sleeve 2 is frictionally charged to a predetermined polarity by the suction force of the magnet roll 3 and the rotation of the developing sleeve 2, and the layer thickness of the toner is regulated to a predetermined value by the doctor blade 5. The toner whose layer thickness is regulated is conveyed to a developing area where the photoreceptor 1 and the developing sleeve 2 are close to or in contact with each other by rotation of the developing sleeve 2, and is provided for developing an electrostatic latent image.

Next, another embodiment of the present invention will be described with reference to FIG. It should be noted that this embodiment has substantially the same configuration as the above-described embodiment, so a description of the same components will be omitted. In the 7 digitator lOb of this example,
Two U-shaped stirring members 9a, 9c are fixed to the rotating shaft 7, and these stirring members 9a, 9
A single coiled auxiliary stirring member 9d is provided by partially penetrating the stirring member c and bridging between the two.

In such a configuration, the portion of the coil 9d extending between the agitation members 9a and 9c is furthermore unrestricted, making it possible to particularly facilitate the movement of toner to the center. It is. The coiled auxiliary stirring member 9d can be configured to contact the surface of the developing sleeve 2, and the coiled auxiliary stirring member 1d can be configured to contact the surface of the developing sleeve 2.
It is also possible to configure it so that it is rotated in contact with the hopper wall 4b or the like.

Next, another embodiment of the present invention will be described with reference to FIG. The overall configuration of the agitator 10c of this embodiment is similar to the agitator 10a shown in FIG. The agitator 10c of this embodiment is not provided with an auxiliary agitation member, but is composed of a rotating shaft 7 and a plurality of (three in this embodiment) agitation members 8 that are fixed to the rotating shaft 7. As is clear from FIG. 4, a feature of the agitator 10c is that the protruding length of the stirring members 8a, 8c at both ends is set longer than that of the stirring member 8b in the center. With such a configuration, it is possible to move the toner from both ends to the center, and in combination with the stirring effect of the toner 6, it is possible to promote the formation of a uniform layer of toner. .

Effects As detailed above, in the developing device of the present invention, by providing a plurality of stirring members along the axial direction of the rotating shaft,
The developer can be stirred more evenly and efficiently compared to conventional techniques. -Also, when an auxiliary stirring member is provided in a movable manner on the stirring member, it is possible to actively stir the toner staying in the vicinity of the doctor tape and prevent the formation of aggregates.
Furthermore, by providing such auxiliary stirring members symmetrically at both ends, it is possible to uniformly supply toner to the circumferential surface of the developing sleeve without the toner being unevenly distributed at both ends of the circumferential surface of the developing sleeve. Therefore, it is possible to obtain high image quality. Further, even if the auxiliary stirring member is disposed so as to be able to contact the peripheral surface of the developing sleeve, the peripheral surface of the developing sleeve will not be damaged, so it is possible to set the stirring range to the maximum. Furthermore, among the plurality of stirring members, those disposed at both ends of the rotating shaft are configured to have a longer protruding length in the radial direction of the rotating shaft than those in the central region, thereby reducing the amount of toner to both ends of the developing sleeve. It is possible to prevent uneven distribution of

It should be noted that the present invention is not limited to the specific embodiments described above, and it goes without saying that various modifications can be made within the technical scope of the present invention.

For example, the auxiliary stirring member 9 is not limited to the coil shape as shown in the illustrated example, but may take any other form.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall structure of a developing device according to an embodiment of the present invention. 2 to 4 show some agitators 10a to 10 applicable to the developing device shown in FIG.
FIG. 6 is a schematic diagram showing a configuration example of e. (Explanation of symbols) 4: Hopper 5: Doctor tap V-dro: Toner 7: Rotating shaft 8: Stirring member 9: Coiled auxiliary stirring member Patent applicant Rico Co., Ltd. - No. 7 WI

Claims (1)

[Scope of Claims] 1. A container for storing developer and provided with an opening; a developer carrier disposed in the opening of the container to carry the developer and transport it to a developing area; a layer thickness regulating means disposed on the upstream side of the developer carrier and facing the developer carrier and regulating the thickness of the developer layer on the peripheral surface of the developer carrier to a predetermined value; and a layer thickness regulating means disposed in the container. 1. A developing device for developing an electrostatic latent image, comprising a plurality of agitating means mounted on a common rotating shaft and spaced apart from each other in the axial direction. 2. The developing device according to item 1 above, characterized in that at least one of the plurality of stirring means is provided with an auxiliary stirring means movable relative thereto. 3. In the above item 1, at least two of the ends of the plurality of stirring means have a protruding length extending in the radial direction from the rotation center of the common rotation shaft. A developing device characterized by being set longer than a stirring means.