JPS59204064A - Toner density detecting device - Google Patents

Abstract

PURPOSE:To form a toner density detecting device for always executing a toner density detection under the same condition without being influenced by a humidity variation of the environment by controlling a developer which has adsorbed and collected magnetically a prescribed quantity of a developer being a toner density detecting sample, to a prescribed shape. CONSTITUTION:A disk-shaped magnet 8 for attracting and collecting a prescribed quantity of a developer 24 rotates at a prescribed speed in the direction as indicated with an arrow, and the developer 24 of a prescribed quantity adsorbed to the magnet 8 passes through a regulating window 5 of a detecting chamber 4 as the magnet 8 rotates. The window 5 has a prescribed shape, therefore, the developer 24 which has passed through the window 5 forms its controlled shape, is adsorbed to the outside circumference of the magnet 8, and goes into a reactor 9 for executing a toner density detection. In order to keep stably the controlled shape and density of the developer 24 until it is detected, a detecting gutter 6 which contacts tightly to an iron core 10 of the reactor 9 and is made of a nonmagnetic material is provided. The developer 24 in the detecting gutter 6 holds a controlled constant shape, therefore, the magneto-resistance is varied only by a magnetic permeability of the developer 24.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a toner concentration detection device for a developer used in an electrophotographic copying machine or the like.

[Prior art]

Accurate 1-toner concentration detection and toner concentration control of a two-component developer containing a mixture of toner and magnetic wax as a carrier are extremely important factors for improving and stabilizing the quality of copied images.

For this purpose, conventionally, the method disclosed in Japanese Patent Publication No. 55-13354 is used, in which the developer is continuously allowed to naturally fall through the hollow part of a toner concentration detection coil.
A method of detecting toner concentration based on a change in coil actance value that occurs based on a change in magnetic permeability of the developer is widely adopted.

[Problems with conventional technology]

However, this method has the drawback that the coil adhesive actance value is greatly affected not only by changes in the I/toner concentration of the developer but also by changes in the fluidity of the developer.

Generally, as the humidity increases, the fluidity of the developer decreases, so in an environment where the humidity changes, the flow of the developer becomes uneven, causing a change in density, and the coil adhesive actance value changes depending on the toner concentration of the developer. It will change due to other reasons. As a result, accurate toner concentration detection becomes impossible, and the toner concentration in the developer becomes unstable, which often causes deterioration in the quality of copied images.

[Purpose of the invention]

The present invention eliminates the above-mentioned conventional drawbacks.

Our objective is to provide a toner concentration detection device that always detects toner concentration under the same conditions without being affected by changes in environmental humidity.
;It is intended to be one target.

[Key points of the invention]

According to the present invention, the second object is to provide a means for magnetically collecting and transporting a two-component developer in which toner and a magnetic material as a carrier are mixed, and a fixed amount of the developer collected by the means. The present invention is characterized by providing means for regulating density and shape, means for stably maintaining the state of the developer regulated by the means, and means for detecting changes in magnetic permeability of the developer regulated. This is achieved by providing a toner concentration sensing device that

[71st Example of the Invention] Hereinafter, one embodiment of the toner concentration detection device according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a side sectional view of a developing device equipped with a toner concentration detection device according to this embodiment, and FIG. 2 is a partially cutaway perspective view of the toner concentration detection device.5 FIG. 3 is a sectional view of the reactor in FIG. 2. , and FIG. 4 is a characteristic curve diagram.

First, the operation of each (shallow groove) of the developing device 1 will be described using FIG.

The stirring blade 15 attached to the shaft 14 is rotated in the direction of the arrow to stir the developer 24.

The magneto roller 16, which has been magnetized at a predetermined position, is covered with a sleeve 17 made of a non-magnetic material, and is given rotation in the direction of the arrow.

The developer 24 attracted by the magneto roller 16 and accumulated on the outer periphery of the sleeve 17 is styled at the tip of the cover 2 to form a magnetic flange 18. The magnetic brush 18 is the tram 2
Toner is applied to the electrostatic latent image on the photosensitive layer 23, which is in contact with the photosensitive layer 23 on the second photosensitive layer 23, to form a visible image. The developer 24 used for development is scraped off by a removal plate 9 and uniformly stirred and mixed by the rotation of stirring blades 15.

However, since the toner concentration of the developer 24 used for development has decreased, it is necessary to replenish the toner.

] - The toner is transferred from the toner bottle 20 to the roller 21 times/l.
” and the developer 24 and stirring 1' supplied for development.
mixed. The developer 24 replenished with toner in this way
forms the magnetic brush 18 for development again, and one or more operations are repeated.

The important problem here is how to accurately detect the 65 degrees of toner in the developer 24 and replenish toner. For this purpose, in this embodiment, a circle fixed to the axis 7! The i-shaped magnet 8 is rotated in the direction of the arrow, and the developer 24 stirred by the two blades 15 is collected by suction as a sample for quantitative tree concentration detection.

Therefore, with reference to FIGS. 2 and 3, a detailed explanation will be given of the operation and function of the toner concentration detection device 3, which is a feature of the present invention.

In FIG. 2, a disc-shaped magnet 8 that sucks and collects a certain amount of developer 24 rotates at a predetermined speed in the direction of the arrow 1i1L, and a certain amount of developer 24 is attracted to the magnet 8.
4 passes through the regulation window 5 of the detection chamber 4 as the magnet 8 rotates. Since the regulation window 5 has a predetermined shape (for example, a rectangle), the developer 24 that has passed through the regulation window 5 forms the regulated shape and absorbs blue around the outer periphery of the magnet 8, thereby detecting the toner concentration. Each time it enters the reactor 9. In order to stably maintain the regulated shape and density of the developer 24 until detection, a detection gutter 6 made of non-magnetic 4A is provided in close contact with the iron core 10 of the reactor 9. The developer 24 whose concentration has been detected is removed by the removal plate 13
As a result, the toner concentration detection process of the developer 24 is completed.

Next, the operation when the toner concentration of the developer 24 is detected in the detection gutter 6 will be explained with reference to FIG.

The developer 24, which has a shape regulated by the regulation window 5 and is attracted near the outer periphery of the magnet 8, is conveyed by the rotation of the disc 8 while coming into contact with the inner surface of the detection gutter 6. Since the detection gutter 6 is made of non-magnetic material, it is not susceptible to magnetic interference.

As shown in FIG. 3, the structure of the reactor 9 is to form a coil 12 on a pobbin 11 and press the iron cores 10 and 10' in the through hole of the pobbin 11 to form a magnetic path. be.

With the reactor 9 formed in this manner, a predetermined alternating current voltage is applied to the coil 12, but no current flows.

Then, the iron cores 10 and 10' have the detection gutter 6 and the
An alternating magnetic flux 25 passing through the developer 24 having the shape of
．． and detection gutter6. Developer having a regulated shape 24. and an alternating magnetic flux 26 passing through the magnet 8. Here, since the developer 24G in the detection gutter 6 maintains a fixed and regulated shape, the magnetic resistance changes only depending on the magnetic permeability of the developer 24. Moreover, since the magnetic permeability of the developer 24 changes depending on the amount of magnetic powder contained in the developer 24, the alternating magnetic fluxes 25 and 26 increase or decrease, and therefore the coil 12
The change in the current flowing through the developer 24 faithfully reflects the change in l-toner concentration of the developer 24. Namely.

When the toner concentration of the developer 24 is low, the amount of magnetic powder is large, so the magnetic resistance decreases, and as a result, the alternating magnetic flux 2
5 and 26 increase, the actance increases and the current flowing into the coil 12 decreases.

Conversely, if the toner concentration of the developer 24 increases, the magnetic resistance increases, and as a result, the alternating magnetic fluxes 25 and 26 decrease, the actance of the coil 12 decreases, and the current flowing into the coil 12 increases. .

The change in reactance due to the change in toner concentration of the developer 24 described above is expressed by the curve 27 in FIG. Therefore, based on the degree values of I to J at the intersection of the curve 27 and the straight line 28 ((
1 setting position 29, it is possible to detect changes in the toner concentration of the developer 24 and control the toner concentration.

That is, when the toner concentration of the developer 24 decreases with respect to the set position 29.

As shown by the curve 27, the reactance of the coil 12 increases, and as a result, the current flowing into the coil 12 decreases from the base p'-value, so that the current flowing into the coil 12 decreases through an electrical circuit (not shown).
I Cola made of sponge material inside the toner bottle 20
21 is rotated a predetermined number of times in the direction of the arrow, I-ner is supplied until the reactance of the coil 12 returns to the set position. The portrait actor 9 can be installed outside the developing device 1, and if necessary, it can be magnetically shielded to prevent noise from the outside. It is also possible to connect a :1 tensor to the coil 12 and set various characteristic curves shown in FIG. 4.

[Results of invention]

As described above in detail, the present invention magnetically collects the developer as a sample for toner concentration detection at a constant rate of 11, and regulates the developer that has been absorbed for several years into a predetermined shape. Since toner concentration detection is always performed under the same conditions of constant amount, constant density, and constant shape, it is possible to perform stable toner concentration detection without being affected by changes in environmental humidity, etc. This is a huge effect.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a developing device, FIG. 2 is a partially cutaway perspective view of a toner concentration detection device according to the present invention without showing the main parts, and FIG.
FIG. 4 is a characteristic curve diagram showing the relationship between the toner concentration of the developer and the coil adhesive actance. DESCRIPTION OF SYMBOLS 1... Developing device, 3... L-toner concentration detection device, 5... Regulation window, 6... Detection gutter. 8...Magneno l-, 9...Reactor. 24...Developer patent applicant Casio Computer Co., Ltd.] NiiD Co., Ltd. Agent Patent attorney Yoshiyuki Suga 1st 1 @2 Figure 3 Figure 4 Toner 5 Nono ε (olo)

Claims (3)

[Claims] (1) A means for magnetically collecting and generally feeding a two-component developer in which a 1-ner and a magnetic material as a carrier are mixed, and a fixed amount of the developer collected by the means. A means for regulating the density and shape, and a means for stably maintaining the state of the developer regulated by the means. A 1 henna 1 concentration detection device, characterized in that it is provided with means for detecting a change in the magnetic permeability of the regulated developer. (2) The toner concentration detection device according to claim 1, characterized in that a gutter made of a non-magnetic material is used as a means for stably maintaining the regulated state of the developer. (3) The toner concentration detection device according to claim 1, wherein a coil is used as a means for detecting a change in magnetic permeability of the regulated developer.