JP2532762Y2 - Developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a developing device such as a copying machine or a laser printer using a two-component developer.

<Prior Art> In a conventional developing apparatus, a mounting position of a toner concentration detector for detecting a toner concentration in a developing tank is a position B in FIG.
As shown by the arrow, it is located at the center between the stirring blades 2 facing the stirring roller 1.

In the drawing, reference numeral 3 denotes a toner concentration detector, and 4 denotes a stirring shaft of the stirring roller 1.

<Problem to be Solved by the Invention> When the toner concentration detector 3 is attached to the central portion B (see FIG. 4) between the stirring blades 2 as in a conventional developing device,
Since the stirring blade 2 moves the developer periodically, the toner concentration detector 3 detects a pressure change of this movement.

As a result, the output of the toner density detector 3 is
Changes in the same cycle as the rotation of, and stable toner density control cannot be performed.

In view of the above, an object of the present invention is to provide a developing device that can prevent the output of a toner density detector from changing with the rotation cycle of a stirring roller and can perform stable toner density control.

<Means for Solving the Problems> As shown in FIGS. 1 to 3, the problem solving means according to the present invention includes a stirring roller 15 for stirring and mixing a toner and a developer in a developing tank 12; And a toner concentration detector 19 for detecting the toner concentration in the developing tank 12 disposed in close proximity to the developing tank 12, wherein the stirring roller 15 is a stirring shaft 20 rotatably supported by the developing tank 12. And the stirring shaft 20
And a plurality of stirring blades 21 that are externally fitted and fixed in an inclined manner, each of the stirring blades 21 is disposed so as not to overlap with each other in the axial direction, and in the middle between the adjacent stirring blades 21 and 21.
The toner concentration detector 19 is attached to a position A where the periodic movement of the developer is small.

<Operation> In the means for solving the above problems, when the toner is supplied into the developing tank 12, the stirring blade 21 of the stirring roller 15 rotates together with the stirring shaft 20 to stir and mix the toner and the developer.

At this time, the toner concentration is detected by a toner concentration detector 19 arranged close to the stirring roller 15.

At this time, since the toner concentration detector 19 is attached to the position A where the periodic movement of the developer is small between the stirring blades 21, the development by rotation of the stirring roller 15 with respect to the toner concentration detector 19 is performed. The change in the pressure of the agent becomes smaller, and the toner concentration detector 19 is less affected by the stirring blade 21.

<Embodiment> An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a view showing a mounting position of a toner concentration detector in a developing device according to an embodiment of the present invention, FIG. 2 is a perspective view of the stirring roller, and FIG. 3 is a sectional view of the developing device.

As shown in FIG. 3, the developing device of this embodiment includes an agitator 13 for pulverizing the toner supplied from the toner supply port 11 into a developing tank 12 having a toner supply port 11 at an upper portion thereof. Agitating rollers 14, 15, 16 for agitating and mixing the toner and the developer, and a developing roller 18 for transporting the developer agitated and mixed by the agitating rollers 14, 15, 16 to a photoreceptor 17, are rotatably provided. A toner concentration detector which is provided and is arranged in close proximity to the stirring roller 15 and detects the toner concentration in the developing tank 12
19 are equipped.

As shown in FIGS. 1 and 2, the stirring roller 15 includes a stirring shaft 20 rotatably supported by the developing tank 12 and the stirring shaft 20.
And a plurality of elliptical stirring blades 21 which are externally fitted and fixed at an angle to 20. The toner density is located at a position A between the stirring blades 21 and 21 where the periodic movement of the developer is small. A detector 19 is attached.

As shown in FIG. 3, the developing roller 18 is disposed close to the photoreceptor 17, is fixed to a roller shaft 22, and is magnetized on a plurality of magnetic poles N1, N2, S1, S2, S3 on a peripheral surface. Magnetic body 23 with magnet
And a non-magnetic sleeve 24 rotatably supported on its peripheral surface
It is composed of Above the developing roller 18, a doctor 25 for regulating the toner scissors formed on the sleeve 24 is arranged in close proximity.

A first stirring roller 14, a second stirring roller 15, a third stirring roller 16, and an agitator 13 are sequentially arranged on the opposite side of the developing roller 18 from the photoconductor 17 toward the toner supply port 11. A first flowing plate 26 is interposed between the first stirring roller 14 and the second stirring roller 15, and the first flowing plate 26
26 and the second stirring roller 15
A third stirring roller 16 is disposed above the third stirring roller. Further, a second flowing plate 27 is disposed between the third stirring roller 16 and the agitator 13.

The stirring rollers 14, 15, 16, the developing roller 18 and the agitator 13 are normally rotated by a motor 28 via a belt mechanism in the direction of the arrow shown in FIG.

As shown in FIG. 3, the toner concentration detector 19 is mounted on the developing tank 12 so as to be close to the lower portion of the stirring roller 15 on the motor 28 side. Then, the mounting position A of the toner density detector 19
As shown in FIG. 1, the toner density detector is located on a straight line connecting the upper end 21a and the lower end 21b of the opposing surfaces of the stirring blades 21 facing each other.
This is where the approximate center of 19 is located.

In the above configuration, the toner supplied from the toner supply port 11 is pulverized by the agitator 13 and is agitated by the stirring rollers 14, 15, 16
To mix with the developer. Then, the developer is conveyed to the photoconductor 17 by the developing roller 18, and the photoconductor 17
Is developed into an electrostatic latent image.

At this time, in the stirring roller 15, the stirring blade 21 rotates together with the stirring shaft 20 to perform the stirring and mixing operation, and the toner concentration is detected by the toner concentration detector 19 arranged in proximity to the stirring roller 15.

At this time, as shown in FIG. 1, the toner concentration detector 19 is mounted at the position A where the periodic movement of the developer is small, between the stirring blades 21 as shown in FIG.
The change in the pressure of the developer due to the rotation of the stirring roller 15 with respect to 19 becomes small, and the toner density detector 19 is less affected by the stirring blade 21.

Therefore, it is possible to prevent the output of the toner density detector from changing with the rotation cycle of the stirring roller, and to perform stable toner density control.

It should be noted that the present invention is not limited to the above embodiment, and it is needless to say that many modifications and changes can be made to the above embodiment within the scope of the present invention.

<Effects of the Invention> As is clear from the above description, according to the present invention, the toner concentration detector is mounted at a position where the periodic movement of the developer is small between the adjacent stirring blades. The change in pressure of the developer due to the rotation of the stirring roller with respect to the toner concentration detector is reduced, and the toner concentration detector is less affected by the stirring blade.

Therefore, there is an excellent effect that the output of the toner density detector is prevented from changing with the rotation cycle of the stirring roller, and stable toner density control can be performed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing a mounting position of a toner density detector in a developing device showing one embodiment of the present invention, FIG. 2 is a perspective view of the stirring roller, and FIG. Sectional view of the device, fourth
FIG. 1 is a diagram showing a mounting position of a toner concentration detector in a conventional developing device. 12: developing tank, 15: stirring roller, 19: toner concentration detector, 20:
Stirring shaft, 21: stirring blade.

Claims (1)

(57) [Scope of request for utility model registration] An image forming apparatus includes: a developing tank provided with a stirring roller for stirring and mixing toner and a developer; and a toner concentration detector disposed in close proximity to the stirring roller and detecting a toner concentration in the developing tank. In the apparatus, the stirring roller includes a stirring shaft rotatably supported by the developing tank, and a plurality of stirring blades that are externally fitted and fixed to the stirring shaft. A developing device, wherein the toner concentration detector is attached at a position between the stirring blades adjacent to each other so as not to overlap with each other and at which the periodic movement of the developer is small.