JPH065418B2 - Electrostatic latent image developing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrostatic latent image developing device in an electrophotographic copying machine or an electrostatic recording device, and more particularly to a developing device provided with a means for detecting the presence or absence of a developer in a developing container. Regarding

(Prior Art) There is known a device for developing an electrostatic latent image formed on the surface of a latent image carrier such as a photoreceptor or a derivative with a powder developer called toner. The toner is usually contained in a hopper type developing container, adheres to the surface of a developing roller provided in the lower opening of the developing container, and is conveyed to the developing position. Due to the development of the electrostatic latent image, the toner in the developing container is gradually consumed and eventually disappears. Since the developing container has almost the same length as the developing roller, the toner consumption amount differs in the length direction, and the partially lacking toner causes a shade in the developed image or white streaks. It may come out. Therefore, it is generally practiced to detect the presence or absence of toner in the developing container early and replenish the toner before an abnormality occurs in the developed image. A means for this purpose is a developer presence / absence detecting device.

As a sensor for detecting the presence or absence of the developer, an optical or magnetic sensor, a contact oscillation stop type sensor, or the like is used. The accuracy of detecting the presence / absence of the developer by these sensors is relatively good, but it often causes malfunction. That is, it is detected that there is a developer even if there is no developer, and vice versa. When the cause was investigated, it was found that the accumulation due to the developer was formed on the inner wall of the hopper above the position where the sensor was attached. The developer in the hopper is agitated by a rotating agitating member to be loosened and adheres to the surface of the developing roller in a state of good fluidity.
Due to the gravity of the developer itself, the intermolecular suction force with the inner wall of the hopper, the pressure of the stirring member against the developer, etc., the adhered developer is gradually generated and the deposit is formed by long-term use. . If such a deposit is above the detection surface of the sensor, this becomes an eaves and a gap is formed between the developer and the detection surface, so that the developer is still sufficiently present in the hopper, The sensor detects that there is no developer. When such accumulation reaches the sensor detection surface, on the contrary, the sensor determines that the developer is present, even though the developer has almost disappeared. In order to prevent such malfunctions, for example, in Japanese Patent Laid-Open Nos. 57-8563 and 56-148017, the detection surface is cleaned at the tip of the developer stirring member, and detection is performed a plurality of times. Techniques for performing the arithmetic processing of the results are shown. However, cleaning the detection surface can prevent malfunction when a developer adheres to the detection surface, but cannot prevent malfunction when a gap is formed in front of the detection surface. In addition, performing the detection a plurality of times and calculating the result has a problem that the device becomes complicated.

(Object of the Invention) In order to solve such a problem, the applicant of the present application has previously described in Japanese Patent Application No. 57-206409 that a motion for preventing the deposition and accumulation of the developer on the upper part of the sensor on the inner wall of the developing container. Although a technique for providing a body has been proposed, an object of the present invention is to improve this technique to provide a developing device that further effectively prevents the deposition and accumulation of the developer.

The configuration of the present invention will be described below with reference to the accompanying drawings.

(Structure of the Invention) In one embodiment of the present invention shown in FIG. 1, a developer adhesion / prevention moving body 1 has a developer presence / absence detection sensor 4 provided on a wall surface in the vicinity of a developing roller 3 in a developing container 2. Is provided above the detection surface 4a. As shown in FIG. 2, the moving body 1 includes a horizontal plate 6 whose one end is swingably supported by a screw 5 substantially parallel to the inner wall surface 2a of the developing container 2.
And a tension coil spring 8 provided between the other end of the horizontal plate 6 and a pin 7 fixed to the inner wall surface 2a below the horizontal plate 6, and the horizontal plate 6 is rotated clockwise by the spring 8. Stopper pin 9 fixed to the inner wall surface 2a for preventing
And an elastic plate 10 such as a mylar film fixed to the horizontal plate 6 so as to cover the inner wall surface 2a above the detection surface 4a of the sensor.

The other end of the horizontal plate 6 has a bent portion 6a, which extends into the rotational trajectory of the tip crossbar 11a of the agitator 11 which is a stirring member in the developing container 2. Therefore, the agitator
When 11 rotates and agitates the developer 12 in the developing container 2,
Since the tip crossbar 11a lifts the bent portion 6a of the moving body 1 in a part of its path, the horizontal plate 6 rotates counterclockwise around the screw 5 and the crossbar 11a further advances and folds. When disengaged from the curved portion 6a, the horizontal plate 6 is turned into a spring 8 this time.
Due to the restoring force of (3), it rotates in the clockwise direction and hits the stopper pin 9 to stop (see FIG. 3). Agitator 11
Since such an operation is repeated every one rotation, the developer 12 is effectively prevented from adhering to and depositing on the inner wall surface 2a above the detection surface 4a of the sensor 4. Further, since the moving body 1 above the detection surface 4a is the elastic plate 10, even when the moving body 1 swings, even if there is a resistance due to the developer 12, it escapes, and the developer deposited on the inner wall surface is removed. Since it can be repelled by the elastic force, the developer adhesion and deposition preventing effect is further enhanced, and the risk of the tamping action of the developer which is expected when the developer is a rigid body is prevented. When the stopper pin 9 is directly fixed to the inner wall surface 2a as in the illustrated embodiment, the lateral plate 6 is returned to the stopper pin 9 by the force of the spring 8, and the entire developing container 2 is affected by the impact. Vibrates,
It is also possible to prevent the developer from depositing and depositing on the inner wall surface of the moving body 1 outside the movable range. Then, as shown in FIG. 4, the tip of the elastic plate 10 is bent so as to contact the inner wall surface 2a, or when the elastic plate 10 is a mylar film or the like, the curling direction is directed to the inner wall surface 2a. By doing so, it is possible to prevent the developer from being clogged between the inner wall surface 2a covered with the elastic plate 10 and the elastic plate 10.

FIG. 5 shows another embodiment of the present invention, in which members similar to those in the above embodiment are designated by the same reference numerals. The horizontal plate 6 of the moving body 1 extends over almost the entire width in the longitudinal direction of the developing container 2, and shafts 13 fixed at right angles to the lateral plate 6 are fixed to the developing container inner wall surface 2a at both ends thereof. By being slidably supported by the bearing 14, the sensor detection surface 4a
Upward and downward movement is possible. This moving body 1
Similarly to the above-mentioned embodiment, the driving of the shaft 13 is such that the tip bending portion 13a of the shaft 13 is
Is hooked on the tip crossbar 11a of the agitator 11 and lifted, and when it is disengaged, it is rapidly lowered until it hits the stopper pin 9 by the spring 8.

In each of the above-described embodiments, the agitator 11 for stirring the developer 12 in the developing container 2 is used as a means for driving the moving body 1, but the power of another rotating body may be used. Alternatively, a dedicated drive source provided for No. 1 may be used.

(Effect of the Invention) As described above, according to the developing device of the present invention, since the plate that moves up and down is provided substantially parallel to the inner wall surface of the developer container above the developer presence detection sensor, the momentum of the moving body is increased. This reduces the size of the device and reduces the cost. It is possible to effectively and directly prevent or remove the adhesion and deposition of the developer on the inner wall surface above the detection surface of the sensor, and the stable operation of the developer presence / absence detection sensor can be obtained over a long period of time. It is possible to significantly improve the sex.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional view showing an embodiment of the present invention.
1 is a perspective view showing the structure of a moving body for preventing developer adhesion and accumulation in the embodiment shown in FIG. 1, FIG. 3 is an operation explanatory view of the moving body shown in FIG. 2, and FIG. FIG. 5 is a partial front view of an inner wall surface of a developing container showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Moving body for preventing developer adhesion and deposition, 2 ... Developing container, 2a ...
Inner wall surface, 3 ... Developing roller, 4 ... Developer presence / absence detection sensor, 4a ... Detection surface, 6 ... Horizontal plate, 11 ... Agitator, 11a ... Tip crossbar.

Claims (1)

[Claims] 1. A stirring member comprising a detection means for detecting the presence or absence of a developer in a developing container and fixed to an inner wall surface of the developing container, and a rotating member arranged in the developing container for stirring the developer. Is provided on the inner wall surface in the vicinity of the upper part of the detection means and can move up and down along the inner wall surface, and moves up and down along the inner wall surface by engaging and disengaging with the rotating stirring member, An electrostatic latent image developing device comprising: a plate-like moving body that prevents the agent from adhering to and depositing on the inner wall surface above the detection means.