JPS5943370A - Apparatus for detecting frequency - Google Patents

Abstract

PURPOSE:To make it possible to detect the resonance frequency of a TM vibrator, by a method wherein the output of a white noise oscillator is applied to two TM vibrators and the outputs thereof are amplified to be inputted to two BPFs while the outputs thereof are taken out. CONSTITUTION:The output signal of a white noise generator 10 is inputted to two vibrators (each being a TM vibrator) each having resonance frequency. When the output signals of the vibrators 1 are inputted to BPF 12, 13, the filtered signal is a detection signal. The TM vibrators 1 operate as filters having two peaks in resonance frequency and generate signals having power spectra as shown by drawings. Because these signals each is bad in an SN ratio, they are passed through an amplifier 11 and BPF 12, 13 to cut frequency components other than resonance frequency and a signal (d) having a power spectrum is outputted. As the result, the measurements of the greater number of the TM vibrators can be simultaneously and instantaneously performed.

Description

Detailed Description of the Invention The present invention provides a vibrator having two resonant frequencies, namely, a main vibration (flexural vibration) for a reference signal and a secondary vibration (screw vibration) for correcting temperature characteristics. A frequency detection device that simultaneously detects the two frequencies of the main vibration and the sub-vibration of the vibrator, which operates to correct deviations in the frequency of the main vibration caused by temperature changes by elastically combining the three vibration modes of the vibrator. Regarding.

Conventionally, in detecting the resonant frequency of the above-mentioned vibrator (hereinafter referred to as TM vibrator), the impedance of the vibrator in the main vibration of the two vibrations of the TM vibrator is approximately Ω as shown in equation 1 (), and the impedance of the vibrator in the main vibration is approximately Ω, and the secondary vibration The impedance of the resonator is on the order of several hundred ohms, which is more than 10 times as large, so it is difficult to oscillate the sub-oscillation with a commonly used oscillation circuit. Therefore, the following two methods are used to find out the frequency sound of sub-vibration. 1st
In this method, an oscillation circuit is used to generate main vibration, which is easy to oscillate, and the temperature around the vibrator is changed.The frequency of the main vibration is measured each time by a counter, and the frequency of the secondary vibration is estimated from the data. This method requires high temperature control of 9 degrees Celsius, and has problems such as the time it takes to stabilize the temperature.

The second method will be explained using the detection method shown in FIG. 1. In FIG. Measure the phase difference between the signal input to the TM oscillator and the signal output from the TM oscillator, analyze the data using the computer 4, and determine the frequencies at the two resonance points. ing.

The method described above involves changing the frequency and analyzing the entire set of operations, so it takes too much time to make a decision.
The apparatus shown in FIG. 1 also has T1. Productivity is poor because only one A transducer can be measured.

In order to eliminate such drawbacks, the present invention aims to eliminate the
The objective is to detect two resonant frequencies at high speed and in large quantities.

To explain this invention based on the drawings, in FIG. The detected signal is a signal that is filtered by the band-pass filters 12 and 13 through the band-pass filter 12.1:3.

The signal generated by the white noise generator 10 has a frequency band including the two resonance points of the TM oscillator 1, and when inputted to the signal iTM oscillator 1 with a uniform power spectrum as shown in FIG. The TM resonator 1 operates as a filter having peaks at two resonance frequencies and generates all signals having the entire power spectrum as shown in FIG. 2C. Since the signal I″iSN ratio is still poor at 1, the amplifier 11 is passed through,
Frequency components other than the resonant frequency are cut by passing through the band pass filters 12 and 13'i.
K, a signal with a power spectrum as shown is output.

The band pass filter 12 is a filter that has peaks in 15 frequency bands, and the band pass filter 13 H
This filter has a peak at a frequency M of 16.

When the signal output from the device is observed with an oscilloscope, it has a waveform as shown in FIG. 3, which is an easy-to-measure waveform with a high S/N ratio that can be measured with an inexpensive device such as a frequency counter. Because of this effect, when the TM resonator 1 is inserted into the device, the resonant frequency is instantaneously output, and the amplifier 1
1 and bandpass filters 12 and x3 in multiple stages as shown in FIG. 4, it becomes possible to simultaneously and instantaneously measure a large number of TM oscillators.

As explained above, if you use this device and connect a frequency counter to its output, you can easily measure the resonance frequency, and you can also detect the resonance frequency of many TM oscillators in parallel at once. By adding the automatic material supply/removal device for the TM vibrator, there is the advantage of making it an automated measuring instrument.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional resonance frequency detection apparatus. FIG. 2 α is a block diagram of the resonant frequency detection device of the present invention. FIG. 2 is a frequency spectrum diagram of the output signal of the white noise generator. Figure 2C is a frequency spectrum diagram of the signal output from the TM resonator. FIG. 2d is a frequency spectrum diagram of the output signal of the pantone filter. FIG. 3 is an oscilloscope diagram of the output signal of the bandpass filter. FIG. 4 is a block diagram when the cL shown in FIG. 2 is multi-staged. 1... TM oscillator 2... Frequency synthesizer 3... Network analyzer 4@lI computer 1 (1... White noise generator 11... Amplifier 12-13, e 7 (and pass filter 15, 16
...Above the peak of the frequency power spectrum at the resonance point of the TN resonator Applicant Suwa Seikosha Co., Ltd. Agent Patent Attorney Mogami Muto 1 已 f 3 MEGA + 11 423-

Claims (1)

[Claims] A device for detecting the resonant frequency of a single vibrator having two resonant frequencies, which includes: a white noise generator that inputs all white noise to the vibrator; an amplifier that amplifies the output from the vibrator; 6. A frequency detection device consisting of two bandpass filters for filtering the output from the device and a frequency counter.