JP2000266594A - Vibration detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a frequency, an amplitude and an acceleration of a vibration by a method wherein a signal spectrum that is generated on a quartz oscillator attached to an object to be inspected due to the external vibration. SOLUTION: A quartz oscillator 1 which is attached to an object to be inspected outputs an oscillating signal fo including side bands at both sides thereof due to an external vibration to form a signal of fo±nΔf ('Δf' represents a frequency of the external vibration and n=1, 2-∞). The signal from the quartz oscillator 1 is FM-detected by an FM-detector 2 and is amplified by an amplifier 3, then an amplitude of a signal with a maximum amplitude and difference in a frequency between two waves having close frequencies are measured by an amplitude/frequency measuring section 4. Data of the amplitude is inputted to an amplitude value calibrating section 5 and is verified with an amplitude calibration table to be calibrated to a real amplitude value. The calibrated amplitude value is the amplitude of the external vibration and the measured frequency is the frequency of the external vibration. The data of the frequency and amplitude is inputted to a data processing section 6 and an acceleration of the external vibration is calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration detecting device, and more particularly, to a device for detecting the frequency, amplitude and acceleration of mechanical vibration using a crystal oscillator.

[0002]

2. Description of the Related Art In order to measure the frequency or magnitude (amplitude) of mechanical external vibration, for example, an element for converting vibration into an electric signal, such as a speaker, is attached to a device under test and output. Although there is a method of observing a signal waveform with an oscilloscope, there is a problem in terms of measurement accuracy and a problem that the device becomes large. In addition, an accelerometer (G meter) was required separately to measure the acceleration.

[0003]

SUMMARY OF THE INVENTION According to the present invention, when mechanical vibration is applied to a crystal oscillator of a crystal oscillator, a side band corresponding to the magnitude of the external vibration is provided on both sides of the oscillation signal at intervals of the frequency of the external vibration. It is an object of the present invention to pay attention to the appearance of a wave spectrum, and to easily and accurately detect the frequency, amplitude and acceleration of external vibration by measuring a sideband wave with a relatively simple device.

[0004]

In order to achieve the above object, a vibration detecting apparatus according to the present invention comprises: a crystal oscillator constituted by using a crystal oscillator; an FM detector for FM detecting an output signal of the crystal oscillator; An amplitude / frequency measuring unit for measuring the amplitude and frequency of the signal from the FM detector, and an amplitude value calibrating unit for calibrating the measured value of the amplitude, wherein the quartz oscillator and the FM detector are attached to the device under test, The amplitude / frequency measurement unit measures the amplitude and frequency of the signal from the FM detector, the amplitude value calibration unit calibrates the amplitude measurement value, and detects an external vibration received by the device under test.

That is, the difference between the frequencies of two signals having the closest frequencies from the FM detector is measured by the amplitude / frequency measuring unit, or the frequency of the oscillation signal of the crystal oscillator and the center frequency from the FM detector are measured. Is measured, and the frequency of the external vibration received by the device under test is detected.

Further, the amplitude / frequency measuring unit measures the amplitude of the signal having the maximum amplitude from the FM detector, and the amplitude value calibrating unit calibrates the amplitude measurement value, or adjusts the center frequency from the FM detector. The amplitude of the signal having the closest frequency is measured, the amplitude measurement value is calibrated by the amplitude value calibrator, and the magnitude of external vibration received by the device under test is detected.

Further, a data processing unit is provided at a stage subsequent to the amplitude / frequency measuring unit, and the amplitude / frequency measuring unit determines the difference between the frequency of the two signals having the closest frequencies from the FM detector and the FM signal.
The amplitude of the signal having the maximum amplitude from the detector is measured, and the data of the frequency difference and the data of the maximum amplitude calibrated by the amplitude value calibrator are input to the data processor, or the amplitude /
The frequency of the oscillation signal of the crystal oscillator and F
The difference between the frequency of the signal closest to the center frequency from the M detector and the amplitude of the signal of the frequency closest to the center frequency from the FM detector are measured, and the data of the frequency difference and the amplitude value calibration unit are used. The calibrated amplitude data is input to the data processing unit, and the maximum acceleration due to external vibration received by the device under test is calculated.

[0008] The data processing section is based on the amplitude data A calibrated by the amplitude value calibrating section and ω (ω = 2πf) obtained from the frequency data f from the amplitude / frequency measuring section, and the displacement X = Asin (ωt + θ) is obtained, the displacement X is differentiated twice with respect to time, and acceleration a = −ω square × Asin (ω
t + θ) is calculated.

Note that a frequency multiplier for multiplying the frequency of a signal from the crystal oscillator or an up-converter for frequency conversion and a transmission unit for wirelessly transmitting a signal from the frequency multiplier or the up-converter are provided downstream of the crystal oscillator. A frequency multiplier or an up-converter, and a transmitter attached to a device under test together with a crystal oscillator, and a frequency before receiving a signal from a transmitter and multiplying by the frequency multiplier at a stage preceding the FM detector; Alternatively, a down converter for converting the frequency to a frequency before conversion by the up converter may be provided, and a signal from the FM detector may be input to the amplitude / frequency measuring unit.

[0010] Alternatively, a PLL circuit using a signal from the crystal oscillator as a reference signal is provided at the next stage of the crystal oscillator, and
The signal from the circuit may be output to the subsequent stage.

It is to be noted that the crystal oscillator may be of a temperature-compensated type to improve the stability against a temperature change.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on embodiments with reference to the drawings. FIG. 1 is a block diagram of a main part of an embodiment of a vibration detecting device according to the present invention. In the figure, a is a part to be attached to a DUT, 1 is a crystal oscillator constituted by using a crystal oscillator, 2 is an FM detector for FM-detecting a signal from the crystal oscillator 1, and 3 is a FM oscillator from the FM detector 2. Amplifying section for amplifying the signal, B is a section installed separately from the DUT mounting section A, 4 is an amplitude / frequency measuring section for measuring the amplitude and frequency of the signal from the amplifying section 3, and 5 is an amplitude / frequency. An amplitude value calibration unit that compares the amplitude data from the measurement unit 4 with an amplitude value calibration table read from a built-in memory, calibrates to true amplitude data, and outputs the data; 6 denotes frequency data from the amplitude / frequency measurement unit 4; And a data processing unit for calculating the acceleration received by the device under test based on the calibrated amplitude data from the amplitude calibrating unit 5.

FIG. 2 is a block diagram of a main part of another embodiment of the vibration detecting device according to the present invention. In the figure, a is a part to be attached to the DUT, 11 is a frequency multiplier for multiplying the frequency of the signal from the crystal oscillator 1 to a frequency that can be transmitted by a small antenna, and 12 is an antenna for the signal from the frequency multiplier 11 13
A transmitting section for wirelessly transmitting the signal is provided at a location apart from the mounting section for the specimen under test, 14 is an antenna, and 15 is a down converter for converting a signal received by the antenna into a frequency before being multiplied by the frequency multiplier 11. In the converter, the signal from the down converter 11 is FM-detected by the FM detector 2. Other symbols are shown in FIG.
Is the same as that of each symbol. Note that the signal from the crystal oscillator 1 may be frequency-converted by the up-converter and transmitted wirelessly via the transmission unit 12.

Next, the operation of the vibration detecting device according to the present invention will be described. First, in the case of FIG. 1, the crystal oscillator 1, the FM detector 2, and the amplifying unit 3 are attached to the DUT. When no external vibration is applied to the device under test, the crystal oscillator 1 operates at a frequency fo (for example, several MHz to several tens
MHz) oscillation signal only. Therefore, the detection output of the FM detector 2 is zero.

When an external frequency f (= Δf) is applied to the crystal oscillator 1, as shown in FIG. 3B, the oscillation frequency fo of the crystal oscillator 1 and the frequency fo about this frequency fo are determined. ± nΔf (n = 1, 2, ~ ∞) sideband ± f1, ± f2,
Output ± f3, ... This spectrum is appropriately amplified by the amplification unit 3, input to the FM detector 2, subjected to FM detection, and ± f1, ± f2, ± f3,... Are extracted, and amplified to an appropriate amplitude by the amplification unit 3. The signal is input to the amplitude / frequency measuring unit 4 shown in FIG. 1B and the two signals having the closest frequencies (f1 and f2, f2 and f
3, -f1 and -f2, etc.) (or the difference between the oscillation frequency fo of the crystal oscillator 1 and the signal f1 or -f1 of the frequency closest to the center frequency from the FM detector 2). Measure. This measured value is the frequency Δf of the external vibration received by the test object.

The amplitude / frequency measuring section 4 also measures the amplitude of the signal of the maximum amplitude input from the FM detector 2 via the amplifying section 3, that is, the signal f1 or -f1 having the frequency closest to the center frequency fo. This data is input to the amplitude value calibrating unit 5, and the amplitude value calibration table stored in the built-in memory is read out and collated, calibrated to the true amplitude value, and the magnitude of the external vibration received by the device under test. (Amplitude).

Further, the data Δf of the frequency from the amplitude / frequency measuring unit 4 and the data of the amplitude calibrated by the amplitude value calibrating unit 5 are inputted to the data processing unit 6, and the data due to the external vibration received by the DUT. Calculate the maximum acceleration. The calculation of the maximum acceleration is performed by calibrating the amplitude data A and the frequency data Δf.
Based on ω (ω = 2πΔf), the displacement X = Asin (ωt + θ) due to vibration is obtained, and the displacement X is differentiated twice with respect to time to calculate acceleration a = −ω square × Asin (ωt + θ).

In the case of FIG. 2, a crystal oscillator 1 and a frequency multiplier
11. Attach the part A consisting of the transmitting unit 12 and the antenna 13 to the DUT and convert the signal from the crystal oscillator 1 to a frequency multiplier.
The signal is input to 11, multiplied by a frequency for transmission by a small antenna 13, amplified by a transmission unit 12, and transmitted wirelessly from the antenna 13. This signal is received by the antenna 14 in the portion B, which is installed separately from the DUT mounting portion A, and the down converter 15
The frequency is converted to the frequency before the multiplication and input to the FM detector 2.
Subsequent operations are the same as those in FIG.
The signal from the crystal oscillator 1 may be frequency-converted by an up-converter.

It should be noted that the crystal oscillator 1
A PLL circuit using a signal (frequency fo) as a reference signal is provided (for example, a signal of several hundred MHz to several GHz). In FIG. 1, this signal is supplied to the FM detector 2 and in FIG. The signal may be input to the multiplier 11 or the signal from the PLL circuit may be multiplied to 10 GHz or more by a frequency multiplier and transmitted as a microwave. The crystal oscillator 1 may be a temperature-compensated type (TCXO). ) To improve stability against temperature changes. The amplitude / frequency measurement unit 4 can use, for example, a spectrum analyzer, an oscilloscope, or an FFT (Fourier transform) analyzer, and the data processing unit 6 can use a personal computer.

[0020]

As described above, according to the vibration detecting apparatus of the present invention, the frequency, amplitude or acceleration of the vibration received by the DUT can be determined by a relatively simple apparatus using a crystal oscillator. It can be detected accurately. Also,
If a crystal oscillator is attached to the DUT, and it is configured to transmit and receive vibration data wirelessly and measure and process data, the DUT is small and the signal line connected for measurement becomes an obstacle. External vibration is suppressed or violent,
Alternatively, it can be easily implemented even in the case where connection with a signal line is difficult due to the arrangement condition of the DUT.

[Brief description of the drawings]

FIG. 1 is a main part block diagram of an embodiment of a vibration detecting device according to the present invention.

FIG. 2 is a main part block diagram of another embodiment of the vibration detecting device according to the present invention.

FIG. 3 is an example of a spectrum of an output signal of a crystal oscillator during excitation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crystal oscillator 2 FM detector 3 Amplification part 4 Amplitude / frequency measurement part 5 Amplitude value calibration part 6 Data processing part 11 Frequency doubler 12 Transmission part 13, 14 Antenna 15 Down converter

Claims (12)

[Claims] 1. A crystal oscillator configured using a crystal oscillator, an FM detector that performs FM detection on an output signal of the crystal oscillator, and an amplitude / frequency measurement unit that measures the amplitude and frequency of a signal from the FM detector. And an amplitude value calibrator for calibrating the measured value of the amplitude. The quartz oscillator and the FM detector are attached to the device under test, and the amplitude / frequency
A vibration detecting device that measures the amplitude and frequency of a signal from an M detector, calibrates the amplitude measurement value with the amplitude value calibration unit, and detects external vibration received by the device under test. 2. The method according to claim 1, wherein the amplitude / frequency measurement unit measures a difference between frequencies of two signals having the closest frequencies from the FM detector to detect a frequency of external vibration received by the device under test. The vibration detecting device according to claim 1. 3. The amplitude / frequency measurement section measures a difference between a frequency of an oscillation signal of the crystal oscillator and a frequency of a signal closest to a center frequency from the FM detector. Vibration detection device. 4. An amplitude / frequency measuring unit measures the amplitude of the signal having the maximum amplitude from the FM detector, and the amplitude value calibrating unit calibrates the amplitude measurement value. 2. The vibration detecting device according to claim 1, wherein the magnitude of the vibration is detected. 5. The amplitude / frequency measurement unit measures the amplitude of a signal having a frequency closest to a center frequency from the FM detector, and the amplitude value calibration unit calibrates the measured amplitude value. 5. The vibration detecting device according to 4. 6. A data processing unit is provided at a stage subsequent to the amplitude / frequency measurement unit, and the amplitude / frequency measurement unit determines the difference between the frequencies of two signals having the closest frequencies from the FM detector,
The amplitude of the signal having the maximum amplitude from the FM detector is measured, and the data of the frequency difference and the data of the maximum amplitude calibrated by the amplitude value calibrating section are input to the data processing section, and the external signal received by the device under test is inputted. 2. The vibration detecting device according to claim 1, wherein a maximum acceleration due to the vibration is calculated. 7. A difference between a frequency of an oscillation signal of the crystal oscillator and a frequency of a signal closest to a center frequency from the FM detector in the amplitude / frequency measurement unit, and a center frequency from the FM detector. 7. The vibration detecting apparatus according to claim 6, wherein the amplitude of a signal having a frequency closest to the frequency is measured, and the data of the frequency difference and the data of the amplitude calibrated by the amplitude value calibrating section are input to the data processing section. 8. The data processing unit calculates ω (ω = 2) obtained from the amplitude data A calibrated by the amplitude value calibration unit and the frequency data f from the amplitude / frequency measurement unit.
πf), displacement X due to vibration X = Asin (ωt + θ)
8. The vibration detecting apparatus according to claim 6, wherein the displacement X is differentiated twice with respect to time to calculate acceleration a = -ω square × Asin (ωt + θ). 9. A frequency multiplier for multiplying a frequency of a signal from the crystal oscillator and a transmission unit for wirelessly transmitting a signal from the frequency multiplier are provided at a subsequent stage of the crystal oscillator, and the frequency multiplier and the transmission unit are provided. Is attached to the device under test together with the crystal oscillator, and a downconverter is provided at a stage preceding the FM detector to receive a signal from the transmitting unit and convert the signal to a frequency before being multiplied by the frequency multiplier. 9. The vibration detecting device according to claim 1, wherein said signal is input to said amplitude / frequency measuring unit. 10. An up-converter for converting a frequency of a signal from a crystal oscillator and a transmission unit for wirelessly transmitting a signal from the up-converter are provided at a subsequent stage of the crystal oscillator, and the up-converter and the transmission unit are connected to the crystal unit. Attached to the device under test together with the oscillator, and a down converter for receiving a signal from the transmitting unit and converting it to a frequency before being converted by the up converter is provided at a stage preceding the FM detector, and a signal from the FM detector is provided. 9. The vibration detecting device according to claim 1, wherein the vibration detecting device is configured to input the signal to an amplitude / frequency measuring unit. 11. The PLL circuit according to claim 1, wherein a PLL circuit using a signal from the crystal oscillator as a reference signal is provided at a stage subsequent to the crystal oscillator, and a signal from the PLL circuit is output to a subsequent stage. Vibration detection device. 12. The vibration detecting device according to claim 1, wherein said crystal oscillator is of a temperature compensation type to improve stability against a temperature change.