JPS61267070A - Developing device - Google Patents

Abstract

PURPOSE:To supply toner into a casing uniformly at any time by providing a supply mechanism which supplies toner into the casing through a toner conveyance path when the toner concn. of a developer decreases and a scooping-up mechanism which scoops up a developer after development in the casing and supplies it into the toner conveyance path. CONSTITUTION:When the toner concn. of the developer D decreases below a constant value as a development stroke is repeated, that is detected by a toner concn. detecting mechanism 10 and the scooping-up mechanism 22 and a screw 13 for toner conveyance are driven. The scooping-up mechanism 22 is driven to attract part of the developer D after development which is scraped off a developing roller 3 and slides down on a recovery plate 9 to the outer periphery of a sleeve 25, and this developer D is supplied from a guide plate 27 into the toner conveyance path 11 through a lead-in opening by a constant amount at every time. Toner is conveyed successively into the toner conveyance path 11 through the screw 13 and mixed with the developer D, and the mixture falls in the casing 2 from each supply hole 12, thus supplying toner to the developer D in the casing 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a developing device used in a dry type electronic copying machine or the like.

[Technical background of the invention and its problems]

First, the conventional structure of this type of developing device is shown in FIG.
In the figure, reference numeral 1 denotes a photoreceptor drum. The surface of the photoreceptor drum 1 is uniformly charged by a charging device (not shown), and in this state, the image of the document is optically exposed by an exposure device (not shown). The image is scanned and formed on the surface of the photoreceptor drum 1 to form an electrostatic latent image.

Reference numeral 2 denotes a casing of a developing device, and a two-component developer consisting of toner and carrier is housed in the casing 2, and a developing roller 3 and an agitator 4 are disposed therein. The developing row 53 is constructed by rotatably fitting a sleeve 7 onto the outer periphery of a magnet roll 6 having a plurality of magnetic poles 5, and the developer material is applied to the outer periphery of the sleeve 7 by the action of the magnetic poles 5. A magnetic brush is formed by adsorption, and the toner of this magnetic brush sequentially adheres to the electrostatic latent image as the photoreceptor drum 1 and sleeve 7 rotate, thereby making the electrostatic latent image visible. This visible image is transferred to a transfer device (not shown).
The image is transferred onto a predetermined copy paper. As the sleeve 7 rotates, the developer adsorbed on the sleeve 7 is conveyed to the development position while being regulated by the regulating body 8 to an appropriate amount necessary for development. The developer residue after development is scraped off by a collection plate 9, returned to the casing 2, and stirred by the stirring member 4. A toner concentration detection mechanism 10 is provided above the collection plate 9, and a decrease in toner concentration is detected by this toner concentration detection mechanism 10.

On the other hand, a U-groove-shaped toner conveyance path 11 is provided on the top surface of the casing 2 along the longitudinal direction of the developing roller 3, and a large number of supply holes 12 are provided on the bottom surface of this conveyance path 11 along the longitudinal direction. A screw 13 for conveying toner is housed in this toner conveying path 11, thereby forming a toner replenishing mechanism 14. When the toner concentration decreases to a constant value by repeating the development process, it is detected by the toner concentration detection mechanism 10, and in response to this detection, the screw 13 rotates, and the toner is conveyed to the toner conveyance path 11. drops into the casing 2 from each supply hole 12 and is replenished, and is stirred by the stirring body 4.

Incidentally, the toner is an extremely fine powder, and therefore, due to the passage of time or changes in the surrounding environment, it partially solidifies within the toner transport path 11, and as a result, it is arranged along the longitudinal direction of the developing roller 3. Some of the supply holes 12 become clogged, and as a result, the supply state of toner to the inside of the casing 2 becomes uneven both in quantity and distribution.

Therefore, as shown in FIG. 5, one end of the collection plate 9 is made to face the inside of the toner transport path 11, and a part of the developer collected from the developing roller 3 is transferred to the toner transport path 11 using the collection plate 9 as a guide.
In some cases, a method is adopted to prevent the toner from clumping together by supplying the toner into the developer layer and adsorbing the toner to this developer layer.

However, in this case, the developer layer is supplied to the toner transport path 11 by the force of sliding down on the collection plate 9 due to its own weight and the force of being pushed out by the developer layer scraped off the developing roller 3.
Therefore, the supply status is uncertain and unstable, making it difficult to fully achieve the intended purpose.

[Purpose of the invention]

The present invention has been made with attention to these points, and its purpose is to accurately supply the developer to the toner transport path, reliably prevent toner from clumping, and ensure that the toner is always uniformly distributed within the casing. An object of the present invention is to provide a developing device capable of replenishing toner.

[Summary of the invention]

That is, in the present invention, a developing roller is provided in a casing containing a two-component developer consisting of toner and carrier, and this developing roller absorbs and conveys a portion of the developer to a developing position, and development is performed using the toner. A toner replenishment mechanism that replenishes toner into a casing through a toner transport path when the toner concentration of the developer decreases, and a pumping mechanism that pumps up the developer after development in the casing and supplies it into the toner transport path. It was designed to be provided.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to FIG. In this embodiment, parts corresponding to the conventional configuration are given the same reference numerals in the drawings, and their explanation will be omitted, and only the different parts will be described.

Inside the casing 2 are first impeller-shaped impellers.
A first stirring body 20.21 is provided, and one end of the recovery plate 9 faces the space between these stirring bodies 20.21. A pumping mechanism 22 is provided diagonally above the collection plate 9, and this pumping mechanism 22 is configured in substantially the same manner as the current roller 3. That is, a sleeve 25 is attached to the outer periphery of a magnet roller 24 having a plurality of magnetic poles 23. are fitted together so that they can rotate freely. An introduction port 26 is formed on one side of the toner conveying path 11 , and a guide plate 27 is connected to the lower edge of the introduction port 26 , and the leading edge of the guide plate 27 faces the upper surface of the sleeve 25 .

Therefore, the developer in the casing 2 is attracted to the outer periphery of the sleeve 7 of the developing roller 3, and as the sleeve 7 rotates, the amount is regulated to an appropriate amount by the regulating body 8, and is transported to the developing position, where it is exposed to light. Contributes to the development of the electrostatic latent image on the body drum r. The developer residue after development is scraped off by the collection plate 9, guided by the collection plate 9, introduced into the area where the first agitation body 20 is arranged, and is sequentially removed by the first agitation body 20 and then the second agitation body 21. It is stirred and prepared for the next development.

When the toner concentration in the developer drops to a certain value by repeating such a development process, this is detected by the toner concentration detection mechanism 10, and in response to this detection, the pumping mechanism 22 and the toner conveying screw 13 are activated. Driven. Then, as the pumping mechanism 22 is driven, a portion of the developed developer that is scraped off the developing roller 3 and slides on the collection plate 9 is applied to the outer periphery of the sleeve 25 due to the magnetic action of each magnetic pole 23. The developer is absorbed into the sleeve 25.
As the toner rotates, a constant amount of toner is sequentially supplied into the toner transport path 11 from the guide plate 27 through the inlet 26. On the other hand, toner is sequentially transported into the toner transport path 11 along the longitudinal direction of the toner transport path 11 by driving the screw 13, and this toner is mixed with the developer. As a result, the toner is replenished to the developer in the casing 2, and the toner concentration is restored.

In this way, the pumping mechanism 22 can stably supply a fixed amount of developer into the toner transport path 11.
Therefore, it is possible to reliably prevent toner from clumping and
Toner can be uniformly replenished from 2 to the developing roller 3 along its longitudinal direction.

The developer to be supplied to the toner transport path 11 is that which has been scraped off from the developing roller 3 and has just been developed. When the toner is supplied to the toner conveying path 11, the toner in the toner conveying path 11 adheres well and its clumping is more reliably prevented. Furthermore, while the toner is passing through the toner transport path 11, the developer is supplied to the toner and preliminary mixing is achieved. Since mixing is performed, there is an advantage that the mixing efficiency is improved.

Note that the amount of developer pumped up by the pumping mechanism can be arbitrarily adjusted by setting the longitudinal dimension and the strength of the magnetic pole. In addition, the pumping mechanism for pumping up the developer is not limited to one that uses magnetic means.
For example, as shown in FIGS. 2 and 3, a plurality of blades 31 are provided evenly around the outer periphery of a shaft 30, and each blade 31 sequentially pumps up the developer as the shaft 30 rotates. It may be.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to reliably and stably supply developer to the toner transport path by the pumping mechanism, and since the developer is after development, it is possible to supply the developer to the toner transport path reliably and stably. This has the effect of reliably preventing the toner from clumping and constantly replenishing the toner uniformly within the casing.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a perspective view showing a modified example of the pumping mechanism, FIG. 3 is a side view, FIG. 4 is a sectional view showing the prior art, and FIG. The figure is a sectional view showing another conventional technique. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (3)

[Claims] (1) A developing roller is provided in a casing containing a two-component developer consisting of toner and carrier, and the developing roller absorbs and conveys a portion of the developer to a developing position, and development is performed using the toner. , a toner replenishment mechanism that replenishes toner into the casing through the toner transport path when the toner concentration of the developer decreases, and a pumping mechanism that pumps up the developer after development in the casing and supplies it into the toner transport path. A developing device characterized by: (2) The developing device according to claim 1, wherein the pumping mechanism pumps up the developer by magnetic means. (3) The developing device according to claim 1, wherein the pumping mechanism is configured in the shape of an impeller, and each blade of the pumping mechanism pumps up the developer.