JPH01282582A - Toner residue detecting device - Google Patents

Abstract

PURPOSE:To accurately detect variation in toner amount varying the relative distance to an electrode or conductor according to the amount of toner nearby the electrode or conductor. CONSTITUTION:The toner in a developing tank 1 is consumed as a copying process is carried on. An electrode plate 5 is pressed against a doctor blade 3 when the toner T is much, but leaves the doctor blade 3 when the toner runs out. A toner residue level signal D decreases gradually right before the electrode plate 5 leaves the doctor blade 3, decreases abruptly the moment the electrode plate 5 leaves the blade, and then decreases gradually. For the purpose, the toner residue level signal D is compared with a proper threshold level signal VTH and a toner emptiness signal is inputted to a CPU when the signal D decreases below the signal VTH to display a toner emptiness state and generate a warning, thereby urging an operator to replenish toner. The detection accuracy is improved as compared with conventional devices.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a device for detecting the amount of toner remaining in a developer tank in an electrostatic image forming apparatus such as a copying machine, a laser beam printer, or a facsimile machine. .

[Prior art]

In the electrostatic image forming apparatus described above, toner is stored in a developer tank, and by rotating a developing sleeve, which is an example of a conductive material, within the developer tank, toner is removed from the toner that adheres to the outer circumferential surface of the developing sleeve. The toner is carried out to the outside of the developer tank, and outside the developer tank, the toner is transferred onto the photosensitive drum to form toner et on the photosensitive drum.

As a method for detecting the amount of toner in the developer tank in such an electrostatic image forming apparatus, for example, Japanese Patent Publication No. 62-62
352, JP-A-59-55462, and JP-A-58-31363.

The one described in Japanese Unexamined Patent Publication No. 58-31364 is known.

These toner remaining amount detection devices have an electrode facing the developing sleeve (conductor) provided in the developer tank, and apply an AC voltage to the conductor to reduce the impedance between the developing sleeve and the electrode. The amount of toner interposed between the conductor and the electrode is detected.

In other words, since the capacitance between the developing sleeve and the electrode is determined by the amount of toner and air present between the two, a change in the amount of toner between the two can be detected as a change in capacitance. It was designed to be obtained.

[Problem to be solved by the invention]

In the toner remaining amount detection device configured to detect the amount of toner interposed between the developing sleeve and the electrode by detecting the capacitance between the developing sleeve and the electrode as described above, in order to improve detection accuracy, the developing sleeve and the electrode are If the toner is brought close to the sleeve, a phenomenon occurs in which the toner becomes blurred between the electrode and the developing sleeve, resulting in a problem of poor detection.

Further, if the distance between the electrode and the developing sleeve is widened in order to prevent such bridging, there is a problem that the change in capacitance with respect to the change in the amount of toner becomes gradual, resulting in a decrease in detection accuracy.

Therefore, the present invention aims to overcome the above-mentioned problems.

[Means to solve the problem]

In order to achieve the above object, the main means adopted by the present invention is to provide an electrode opposite to a predetermined conductor provided in the developer tank, apply an alternating current voltage to the four electric bodies, and respond to this. In the remaining toner M detection device, the amount of toner interposed between the conductor and the electrode is detected by measuring the induced voltage of the electrode induced by the electrode. A toner remaining amount detection device configured to move according to the amount of toner near the electrode or conductor, and to be configured such that the relative distance to the conductor or electrode can vary according to the amount of toner. be.

[Effect]

In this invention, when the amount of toner near the electrode or conductor increases, for example, the electrode or conductor approaches (or moves away from) the conductor or electrode relatively, and the amount of toner decreases, and in extreme cases, the toner runs out. Then, the electrode or conductor moves away from (or approaches) the conductor or electrode, and the capacitance between the electrode and the conductor changes drastically, so that changes in the amount of toner can be detected with high accuracy.

〔Example〕

Next, embodiments embodying the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention. here the first
Figures (al and (bl) are schematic side sectional views showing the movement of each element in the developer tank of a remaining toner amount detection device according to an embodiment of the present invention, and Fig. 2 is a circuit showing the configuration of the detection device. 3 is a waveform diagram showing signal waveforms of each element in the circuit diagram shown in FIG. 2, and FIG. 4 is a waveform diagram showing changes in the remaining toner level signal and changes in the toner empty signal in the same embodiment. It is.

In addition, the following example is only an example of embodying the present invention,
This is not intended to limit the technical scope of the present invention.For example, in the following embodiments, the electrode plate, which is an example of an electrode, is movable, but conversely, it is also possible to make the conductor side movable.

First, with reference to FIG. 1, the structure of a developer tank that can be used with the remaining toner amount detection device according to this embodiment will be described.

This developing tank 1 utilizes the so-called jumping phenomenon.
This is a type in which toner is supplied in small amounts from a developing sleeve 2 to a photosensitive drum (not shown). The doctor blade 3 is pressed against the developing sleeve 2, and the developing sleeve 2, which rotates in the direction of arrow X, regulates the amount of toner conveyed to the developing section between the photosensitive drum and the developing sleeve 2.

In the vicinity of the doctor blade 3, an electrode plate 5 (electrode) is provided which is swingable about a shaft 4. As shown in FIG.
It is pushed by and swings in the direction approaching the doctor blade 3. As shown in FIG. 1), when the toner T decreases and the top surface of the electrode plate 5 separates from the electrode plate 5, its own weight causes the electrode plate 5 to move as shown in FIG. 1(b). ,
It is configured to be separated from the doctor blade 3.

Further, a stirring device 6 is provided in the developer tank 1 as required. This stirring device 6 constantly stirs the toner T in order to prevent the toner T contained in the developer tank 1 from solidifying. is pushed out in the direction of the electrode plate 5, whereby the electrode plate 5 can be pressed against the doctor blade 3.

In this embodiment, an alternating voltage is applied to the doctor blade 3 and the developing sleeve 2 as shown in FIG. 2, and the electrode plate 5 is connected to the input terminal of the buffer circuit 8 of the toner detection circuit 7. There is.

The waveform (A) shown in FIG. 3 is a waveform diagram of the AC voltage applied to the doctor blade 3 and the developing sleeve 2, and the waveform (B) shows the output signal from the buffer circuit 8.

The output signal from the buffer circuit 8 is further input to a low pass filter 9. The output signal C from the low-pass filter 9 is as shown in FIG. Therefore, the remaining toner level signal obtained through the peak hold circuit 10 is as shown in FIG.
The value is related to the amount of toner multiplied by N in the vicinity of .

As described above, the toner in the developing tank 1 decreases for a while as the copying process continues and the toner is consumed. It is in a state of being forced. As shown in FIG. 1 (bl), when the toner that presses the electrode plate 5 runs out, the electrode plate 5 separates from the doctor blade 3.

From the state shown in FIG. 1 fat until the electrode plate 5 is about to separate from the doctor blade 3, the remaining toner level signal gradually decreases as shown in FIG. 4+81. As shown in (b), the moment the electrode plate 5 separates from the doctor blade 3, the remaining toner level signal rapidly decreases, and then gradually decreases again.

Therefore, as shown in FIG. 4, the appropriate threshold level signal TH and the remaining toner level signal
1, and when the remaining toner level signal falls below the threshold level signal vTS, the toner empty signal "Er1P" is sent to the microcomputer CPU.
Enter.

The 4th issue) shows a waveform diagram of such a toner empty signal T.

When the microcomputer CPU receives such a toner empty signal T Il:mP, it prompts the operator to replenish toner by displaying toner empty or by issuing a well signal.

In the above embodiment, a case where the present invention is applied to a so-called jumping type copying machine has been explained, but the present invention can also be applied to a copying machine in which a magnetic brush is formed by a so-called cutting board, a laser beam printer, a facsimile machine, etc. The invention is applicable.

Further, in the above embodiment, the doctor blade 3 is used as an example of the conductor, but such a conductor is connected to another electrode provided relatively near the bottom of the developer tank so that the remaining amount of toner can be detected. It is also possible to configure it by, etc. Therefore, it is of course possible to select the developing sleeve 2 as a conductor. In this case, it is desirable to provide a contact that prevents the electrode from coming into direct contact with the developing sleeve so as not to interfere with toner replenishment.

Further, in the above embodiment, when the toner becomes low due to the weight of the electrode plate 5, the electrode plate 5 swings in the direction away from the opposing conductor. The electrodes may be oscillated in combination with self-m.

Further, when the amount of toner is large, the electrode moves away from the conductor, and conversely, when the amount of toner is small, the electrode can move closer to the conductor.

As mentioned above, since the distance between the electrode and the conductor only needs to be changed relative to each other, the conductor side may be movable.

〔Effect of the invention〕

As described above, the present invention provides an electrode opposite to a predetermined conductor provided in a developer tank, applies an alternating current voltage to the conductor, and induces the electrode in response to this. In a toner remaining amount detection device that detects the amount of toner present between the four electric bodies and the electrode by measuring voltage, the electrode or four electric bodies are used to detect the amount of toner present in the vicinity of the electrode or conductor. The toner remaining amount detection device is characterized in that it is configured such that it moves according to the amount of toner and the relative distance to the conductor or electrode can vary depending on the amount of toner. Since the electrode or the four electric bodies themselves move according to the amount of toner in the vicinity, the change in capacitance between the electrode and the conductor due to fluctuations in the amount of toner becomes significantly large, compared to conventional toner remaining amount detection devices. The detection accuracy is significantly improved.

[Brief explanation of the drawing]

Fig. 1 fat and (bl are respectively schematic side sectional views showing the movement of each element in the developer tank of a remaining toner amount detection device according to an embodiment of the present invention, and Fig. 2 shows the configuration of the same detection device. 3 is a waveform diagram showing signal waveforms of each element in the circuit diagram shown in FIG. 2, and FIG. 4 is a waveform showing changes in the remaining toner level signal and changes in the toner empty signal in the same embodiment. [Explanation of symbols] 1...Developer tank 2...Developer sleeve 3...Doctor blade (4 electric bodies) 5...Electrode plate (7Fi pole) 6...Agitator 7. ... Toner remaining amount detection circuit 8 ... Bumper circuit 9 ... Low pass filter 10 ... Peak hold circuit 11 ... Comparator.

Claims (1)

[Claims] 1. By providing an electrode opposite to a predetermined conductor provided in the developer tank, applying an alternating current voltage to the conductor, and measuring the induced voltage of the electrode induced in response to this, In the remaining toner amount detection device that detects the amount of toner interposed between the conductor and the electrode, the electrode or the conductor is moved in accordance with the amount of toner near the electrode or the conductor, and the conductor is A toner remaining amount detection device characterized in that the relative distance to the body or the electrode can be varied depending on the amount of toner.