JP3771336B2 - Liquid evaluation system using interdigital converter - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a liquid evaluation apparatus using an interdigital converter that measures the viscosity and electrical characteristics of a liquid to be inspected and evaluates the liquid to be inspected.
[0002]
[Prior art]
Conventionally, a piezoelectric thin film is bonded to the surface of a copper plate, one interdigital electrode and the other interdigital electrode are formed on opposite sides of the piezoelectric thin film, and one input terminal and output terminal are formed on the one interdigital electrode. A liquid provided on the piezoelectric thin film between the one input terminal and the output terminal by combining the other interdigital electrodes, combining the other interdigital electrode with the interdigital electrodes of the other input terminal and the output terminal, respectively. Fill one hole of the cell with one non-inspection liquid, open a hole in the piezoelectric thin film between the other input terminal and output terminal, and attach the other hole of the liquid cell to the hole of the piezoelectric thin film Using the interdigital converter formed by filling the other hole of the liquid cell with the other non-inspection liquid, the characteristic of the liquid is detected from the difference in sound velocity propagating between the respective input terminals and output terminals. Method proposed Are (see JP-A-7-318541 and JP-A No. 7-318542).
[0003]
[Problems to be solved by the invention]
However, in the method of detecting the liquid property using such an interdigital converter, it is not clear whether the difference in the speed of sound propagating is due to the acoustic property of the liquid or the electrical property. There was a drawback that it was not possible to evaluate.
[0004]
[Means for Solving the Problems]
In the present invention, a conductive thin film is bonded onto a piezoelectric substrate, one interdigital electrode and the other interdigital electrode are formed on opposite sides of the conductive thin film, and one input terminal and one interdigital electrode are connected to the one interdigital electrode. Combining the interdigital electrode of the output terminal, combining the interdigital electrode of the other input terminal and the output terminal with the other interdigital electrode, and the liquid provided on the conductive thin film between the one input terminal and the output terminal One hole of the cell is filled with one liquid to be inspected, a hole is formed in the conductive thin film between the other input terminal and the output terminal, and the other hole of the liquid cell is fitted to the hole of the conductive thin film. The other hole of the liquid cell is filled with the other liquid to be inspected, an amplifier is mounted between the one and the other input terminal and the output terminal, and a frequency counter is connected to each output terminal of the amplifier It is.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, by connecting an amplifier between one input terminal and the output terminal to cause self-oscillation, the ultrasonic vibration passing on the conductive thin film is influenced by the liquid to be inspected. Since the liquid to be inspected that is detected by the frequency and provided between the other input terminal and the output terminal does not have a conductive thin film, the liquid to be inspected passes through the liquid to be inspected as an electrical signal from the conductive thin film on the input terminal side, and The electric signal is converted into an acoustic signal by the conductive thin film, and the electric signal between the conductive thin films is affected by the liquid to be inspected. Therefore, this electric characteristic is detected at the self-oscillation frequency.
[0006]
【Example】
FIG. 1 is a configuration diagram of a liquid evaluation apparatus using an interdigital converter according to an embodiment of the present invention. FIG. 2 is an enlarged view of the interdigital converter of FIG. 1, and a conductive thin film 2 is mounted on a piezoelectric substrate 1. Then, interdigital electrodes 2a and 2b are formed on one opposing side of the conductive thin film 2, and interdigital conductors 2c and 2d are formed on the other opposing side of the conductive thin film 2. The interdigital electrode 3a of one input terminal 3 is combined, the interdigital electrode 4a of one output terminal 4 is combined with the interdigital electrode 2b, and the interdigital electrode 5a of the other input terminal 5 is combined with the interdigital electrode 2c. The interdigital electrode 6a of the other output terminal 6 is combined with the interdigital electrode 2d.
[0007]
A quadrilateral hole 2e is formed between the other input terminal 5 and the output terminal 6 of the piezoelectric thin film 2, and the hole 7a of the silicon rubber 7 provided with the holes 7a and 7b coincides with the hole 2e of the piezoelectric thin film 2. The interdigital converter 9 is configured by mounting the liquid cell 8 so that the filling holes 8a and 8b of the liquid cell 8 coincide with the holes 7a and 7b of the silicon rubber 7.
[0008]
The output terminals 4 and 6 of the interdigital converter 9 configured in this way are connected to the input terminals of the amplifiers 10 and 11, respectively, and the output terminals of the amplifiers 10 and 11 are connected to the input terminals 3 and 5 of the interdigital converter 9, respectively. In addition to being connected, they are connected to frequency counters 12 and 13, respectively.
[0009]
In the liquid evaluation apparatus using the interdigital converter of this embodiment configured as described above, an amplifier 10 is connected between one input terminal 3 and the output terminal 4 of the interdigital converter 9 to cause self-excited oscillation. Since the ultrasonic vibration propagating from the piezoelectric thin film 2 to the liquid is affected by the liquid to be inspected filled in the filling hole 8a of the liquid cell 8, the frequency counter 12 detects the frequency of this self-excited oscillation. An acoustic characteristic of the liquid to be inspected is detected.
[0010]
Further, since the liquid to be inspected filled in the filling hole 8b of the liquid cell 8 provided between the other input terminal 5 and the output terminal 6 is put in the portion of the hole 2e of the conductive thin film 2 where there is no conductive thin film, the input terminal From the sound wave transmitted through the piezoelectric substrate on the 5 side, an electric field passes through the liquid to be inspected, and is converted into an acoustic signal by the conductive thin film on the output terminal 6 side, and an electric signal between the conductive thin films is affected by the liquid to be inspected. By detecting the frequency of this self-excited oscillation with the frequency counter 13, the electrical characteristics of the liquid to be inspected are detected.
[0011]
Thus, in the embodiment of the present invention, the amplifiers 10 and 11 are connected between the input terminals 3 and 5 and the output terminals 4 and 6 provided in the interdigital converter 9, and the output terminals of these amplifiers 10 and 11 are connected. Further, the frequency counters 12 and 13 are connected to each other, so that the acoustic characteristics and electrical characteristics of the liquid to be inspected can be detected by the self-excited oscillation frequency. Therefore, there is an advantage that the workability is excellent and the configuration is simple.
[0012]
【The invention's effect】
As described above, in the liquid evaluation apparatus using the interdigital converter of the present invention, an amplifier is connected to the input and output terminals of the interdigital converter, and a frequency counter is connected to the output terminal of the amplifier. Since the acoustic characteristics and electrical characteristics of the test liquid can be detected, there is an advantage that the configuration is simple and the workability is good.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a liquid evaluation apparatus using an interdigital converter according to an embodiment of the present invention.
FIG. 2 is an enlarged perspective view of the interdigital converter of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Piezoelectric substrate 2 Piezoelectric thin film 3, 5 Output terminal 4, 6 Output terminal 7 Silicon rubber 8 Liquid cell 9 Interdigital converter 10, 11 Amplifier 12, 13 Frequency counter

Claims (1)

  A conductive thin film is formed on the piezoelectric substrate, one interdigital electrode and the other interdigital electrode are formed on opposite sides of the conductive thin film, and one input terminal and an output terminal interdigitally are formed on the one interdigital electrode. One of the liquid cells provided on the conductive thin film between the one input terminal and the output terminal is combined with the other interdigital electrode and the interdigital electrode of the other input terminal and the output terminal. The liquid cell is filled with one liquid to be inspected, a hole is formed in the conductive thin film between the other input terminal and the output terminal, and the other hole of the liquid cell is fitted to the hole of the conductive thin film. The other hole is filled with the other liquid to be inspected, an amplifier is mounted between the one and the other input terminal and the output terminal, and a frequency counter is connected to each output terminal of the amplifier. Interdigital Liquid test system using exchangers.

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