JPH05142184A - Electrostatic sensor apparatus - Google Patents

Abstract

PURPOSE:To improve the degree of freedom for installation and the stability of the title apparatus so as to reduce its size by adopting a radio transmission route consisting of radiation means and wave-receiving means to send a drive reference frequency signals to a ceramic resonance means. CONSTITUTION:A radiator 2 radiates reference frequency signals, while wave receiving apparatuses 3a-3c receive the radiated reference frequency signals. High-frequency amplifiers 4a-4c amplify the radiated reference frequency signals into the drive reference frequency signals, and since respective ceramic resonators 5a-5c output the signals with any amplitude corresponding to the drive reference frequency signals based on each resonance characteristics, the amplitude of each signal may vary accompanied with the change of respective resonance characteristics. Detectors 8a-8c extract the changes of signal amplitude and output the electrostatic capacity detection signal consequently. The drive reference frequency signals are supplied for the ceramic resonance means by means of radio wave, so that the degree of freedom for installation can be improved, and furthermore the stability can be also improved because the characteristic change of one channel gives no influence on oscillation means or other channels. The ceramic resonance means is adopted so as to reduce the size as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic sensor device, and more particularly to an electrostatic sensor device useful for controlling the thickness, uniformity, etc. of a sheet-like material (paper, plywood, etc.).

[0002]

2. Description of the Related Art FIG. 2 is a block diagram of an example of a conventional electrostatic sensor device. The electrostatic sensor device 200 has three pairs of electrodes 6a and 7a, 6b as three independent detection units.
And 7b, 6c and 7c and each stripline resonator 5
5a, 55b, 55c. The strip line resonators 55a, 55b, 5 are formed by the capacitance between the electrodes of each pair.
The resonance characteristic of 5c is determined. One detector is called a channel. Therefore, the electrostatic sensor device 200 is a three-channel electrostatic sensor device.

Each stripline resonator 55a, 55
The reference frequency signal of about 1 GHz output from the OSC 2 is supplied to the matching circuits 52a, 52b, b, 55c.
52c and strip lines 53a, 53b, 53c
Also, it is supplied as a drive reference frequency signal via the matching circuits 54a, 54b, 54c.

Each stripline resonator 55a, 55
b and 55c each output a signal having an amplitude corresponding to the drive reference frequency signal based on each resonance characteristic,
When the capacitance between the electrodes of each pair changes and each resonance characteristic changes, the amplitude of each signal changes.

The detectors 8a, 8b, 8c extract changes in the amplitude of the signals output by the stripline resonators 55a, 55b, 55c and output them as capacitance detection signals, respectively.

Therefore, by these capacitance detection signals,
For example, it is possible to detect the thickness of the sheet-like material that passes between the electrodes of each pair.

[0007]

In the conventional electrostatic sensor device 200 described above, the stripline resonators 55a and 55a are arranged.
The matching circuits 52a, 52b, 52c, the strip lines 53a, 53b, 53c, and the matching circuit 5 are used to supply the drive reference frequency signals to 5b, 55c.
4a, 54b, 54c are used. Therefore, there is a problem in that the installation location is restricted, for example, all the channels must be installed on the same substrate as the OSC2. In addition, since it is difficult to achieve perfect matching, the characteristic variation of one channel due to temperature affects the OSC 2 and other channels, and there is a problem in stability.
Further, since the stripline resonator is used, there is a problem that the size becomes large.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrostatic sensor device which has improved installation flexibility and stability and can be miniaturized.

[0009]

An electrostatic sensor device according to the present invention includes at least a pair of electrodes, ceramic resonance means for changing resonance characteristics according to a change in capacitance between the electrodes, and a reference frequency signal. Oscillating means for oscillating, radiating means for radiating the reference frequency signal as a radiation reference frequency signal, and at least 1 for receiving the radiation reference frequency signal
One wave-receiving means and an amplifying means for amplifying the radiation reference frequency signal received by the wave-receiving means and supplying it to the ceramic resonance means as a drive reference frequency signal. The structural feature is to detect as a change in the output of the ceramic resonance means.

[0010]

In the electrostatic sensor device of the present invention, the radio transmission line constituted by the radiation means and the wave reception means is used for supplying the driving reference frequency signal to the ceramic resonance means. Therefore, the oscillating means and the resonating means can be installed on different substrates, and the degree of freedom of installation is improved. In addition, the characteristic variation of one channel does not affect the oscillating means and the other channels, so that the stability is improved. Further, since the ceramic resonance means is used, the size can be reduced.

[0011]

The present invention will be described in more detail below with reference to the embodiments shown in the drawings. However, this does not limit the present invention. FIG. 1 is a block diagram of an electrostatic sensor device 100 according to an embodiment of the present invention.

The electrostatic sensor device 100 is a three-channel electrostatic sensor device, and has three pairs of electrodes 6a and 7a, 6b and 7b, 6c and 7c, and a ceramic resonator 5a as three independent detecting portions. , 5b, 5c. Depending on the capacitance between the electrodes of each pair, each ceramic resonator 5a, 5
The resonance characteristics of b and 5c are determined. Ceramic resonator 5
a, 5b, and 5c are disclosed, for example, in "The Proceedings of the 1st Annual Meeting of the Institute of Electrical Engineers of Japan, 1991 to P.1-41 to P.1-42".

On the other hand, the OSC1 has an oscillation frequency of about 1 GHz and outputs it as a reference frequency signal.

The radiator 2 radiates the reference frequency signal as a radiation reference frequency signal. As the radiator 2, for example, λ / n microstrip line (n is a positive integer)
To use.

The receivers 3a, 3b, 3c of each channel are
Receiving the radiation reference frequency signal. Receiver 3a, 3
For example, λ / n microstrip lines are used as b and 3c.

The high frequency amplifiers 4a, 4b and 4c amplify the received radiation reference frequency signal and supply it to the respective ceramic resonators 5a, 5b and 5c as a driving reference frequency signal.

Each ceramic resonator 5a, 5b, 5c is
Amplitude signals corresponding to the drive reference frequency signal are output based on each resonance characteristic, so that if the capacitance between the electrodes of each pair changes and each resonance characteristic changes, the amplitude of each signal changes. To do.

The detectors 8a, 8b and 8c extract changes in the amplitude of the signals output from the ceramic resonators 5a, 5b and 5c and output them as capacitance detection signals, respectively.

Therefore, by these capacitance detection signals,
For example, it is possible to detect the thickness of the sheet-like material that passes between the electrodes of each pair.

Although the above embodiment has three channels,
The number of channels is arbitrary.

[0021]

In the electrostatic sensor device of the present invention, since the drive reference frequency signal is supplied to the ceramic resonance means by radio waves, the degree of freedom in installation is improved. In addition, the characteristic variation of one channel does not affect the oscillating means and the other channels, so that the stability is improved. Further, since the ceramic resonance means is used, the size can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of an electrostatic sensor device of the present invention.

FIG. 2 is a block diagram of an example of a conventional electrostatic sensor device.

[Explanation of symbols]

 100 electrostatic sensor device 1 OSC 2 radiator 3a, 3b, 3c wave receiver 4a, 4b, 4c high frequency amplifier 5a, 5b, 5c ceramic resonator 6a, 7a electrode 6b, 7b electrode 6c, 7c electrode

Claims (1)

[Claims] 1. At least a pair of electrodes, ceramic resonance means for changing resonance characteristics according to a change in capacitance between the electrodes, and oscillation means for oscillating a reference frequency signal.
Radiating means for radiating the reference frequency signal as a radiation reference frequency signal, at least one wave receiving means for receiving the radiation reference frequency signal, and a drive reference for amplifying the radiation reference frequency signal received by the wave receiving means. An electrostatic sensor device comprising: an amplifying unit that supplies a frequency signal to the ceramic resonance unit, and detects a change in capacitance between the electrodes as a change in output of the ceramic resonance unit.