JP2569069Y2 - Automatic sensitivity switching device for vibration meter - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an automatic sensitivity switching device for a vibration meter such as a seismic observation device, which can automatically switch the gain and perform appropriate recording regardless of the magnitude of the vibration. About.

[0002]

2. Description of the Related Art Conventional vibrometers such as seismic observation devices are designed to constantly observe and record vibrations, but the recording automatically measures vibrations of various amplitudes from small to large. It is necessary to record at a good S / N ratio. Therefore, for example, as shown in FIG.
Is amplified by the amplifier 2 and recorded in the recording device 3.

[0003] At this time, whether the vibration is small or large,
Since it is desirable that the data recorded in the recording device 3 be recorded at a value as close to full scale as possible, the output value of the amplifier 2 is input to the comparators 4 and 4 ', and the reference voltage generating device having different reference voltages is used. The reference signal output from 5, 5 'is compared with the output of the amplifier 2. When the output of the amplifier 2, that is, the detected value of the vibration observed at that time is increased or decreased as compared with the voltage of the reference signal value output from the reference voltage generators 5, 5 ', the corresponding comparison is made. The devices 4 and 4 'respectively output gain switching signals, and the switching switches 6 and 6' are respectively switched by the switching signals, so that the amplification degree of the amplifier 2 is automatically switched. In this way, recording is always performed on the recording device 3 with an amplitude close to full scale regardless of the magnitude of the vibration.

[0004]

However, in such a conventional amplification degree switching means, the comparators 4 and 4 'for comparing the magnitude of the output signal from the amplifier 2 with the magnitude of the reference signal, and the reference signal generator 5 , 5 ′ and changeover switches 6, 6 ′, etc., which complicate the structure. Further, when the output of the amplifier 2 increases or decreases near the value of the reference signal, the gain switching is frequently repeated, and there is a problem that the recording offset frequently occurs with the gain switching. . The present invention has been made in view of such a conventional problem, and has as its object to provide an automatic sensitivity switching device having a simple structure and capable of smoothly switching the sensitivity.

[0005]

Means for solving the above-mentioned problems in the present invention is a vibration measuring device which amplifies a detection value from a vibration sensor with an amplifier and records the amplified value on an analog recording device. An A / D converter for converting an output from the amplifier into a digital signal, an information processing device for reading a signal from the A / D converter, instructing switching of sensitivity according to the level of the read value, and converting the read value;
D for converting the output value of the information processing device into an analog signal with a smaller number of bits than the number of bits of the AD converter
An A converter and a D / A converter for a sensitivity switching signal that receives a sensitivity switching signal from the information processing device, outputs the signal as a staircase analog signal, and inputs the signal to the analog recording device. It is.

[0006]

Next, the operation of the present invention will be described. The detected value from the vibration sensor is amplified by an amplifier, and the output from the amplifier is converted into a digital signal by an AD converter.
The information processing device reads the signal from the A / D converter, instructs the switching of the sensitivity in accordance with the level of the read value, and converts the read value to be convenient for the subsequent data processing. The output of the information processing device is converted into an analog signal by a DA converter. Since the number of bits of the DA converter is smaller than the number of bits of the AD converter, the MSB of the digital value of the DA converter is converted. The digit of the MSB of the AD converter is always set in the digit.

In this way, when the numerical value of the AD-converted digital signal is small, the blank value in the upper digit is omitted, and when the numerical value of the AD-converted digital signal is large, the lower numerical value is truncated. Is switched by the information processing device so that the measured value is always output from the DA converter at a value close to the full scale. In addition, the measured value converted by the information processing device into a form convenient for
Is converted.

The sensitivity switching signal DA converter receives the sensitivity switching signal from the information processing device and outputs the signal as a step-like analog signal depending on the level of the sensitivity switching. This is input to an analog recording device, and is recorded simultaneously with the output of the original vibration.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
FIG. 1 is a diagram showing a configuration of the present invention. In a vibration measuring device 10, a detection value from a vibration sensor 11 is amplified by an amplifier 12 and recorded in an analog recording device 13. There is an AD converter 14 having a large number of bits for converting the output from the amplifier 12 into a digital signal.
There is an information processing device 15 which reads a signal from the controller and instructs switching of the sensitivity in accordance with the level of the read value and converts the read value. Further, a DA converter 16 that converts the output value of the information processing device 15 into an analog signal with a smaller number of bits than the number of bits of the AD converter 14 is provided.

A D / A converter 17 for a sensitivity switching signal is provided separately from a D / A converter 16 for an output signal so that the sensitivity switching signal output in a stepwise manner is input to the analog recording device 13.

FIG. 2 shows an earthquake observation device 2 as a vibration measuring device.
0, and the detected value from the vibration sensor 21 is
2, and the vibration waveform is recorded in the analog recording device 23. The output from the amplifier 22 is input to an AD converter 24 having 16 bits, and there is an information processing device 25 that reads a signal from the AD converter 24 and converts the read value.

The information processing device 25 receives the output of the AD converter 24 and performs sensitivity switching and other information processing based on the output.
And the sensitivity switching signal DA converter 27. The output signal DA converter 26 has 12 bits whose bit number is 4 bits smaller than the bit number 16 of the AD converter 14, and is output from the AD converter 24 as instructed by the information processing device 25. And outputs the signal. The D / A converter 27 for the sensitivity switching signal outputs the level of the switched output. The outputs of both the output signal DA converter 26 and the sensitivity switching signal DA converter 27 are input to an analog recording device 23 so that the vibration waveform and the current level of the sensitivity switching are recorded. Has become.

When a seismic motion is detected by the vibration sensor 21,
The detected value is input to the amplifier 22, and the signal amplified by the amplifier 22 is input to the A / D converter 24, and this signal is directly subjected to A / D conversion with 16-bit accuracy at full scale. Next, the information processing device 25 receives the 1
A 6-bit signal is read, and a command to switch the sensitivity as a digital value is issued depending on whether the level of the read numerical value is large or small. Also, the read values can be converted to a logarithmic scale, and can be converted in any way, such as by multiplying by a coefficient for convenient later data processing.

Next, a processing method of the information processing device 25 when the sensitivity is switched will be described. The measurement value digitized by the AD converter 24 is input to the information processing device 25 for processing, and the output value is output to the output signal DA converter 2.
6, the signal is converted into an analog signal.
The bit number of 6 is 12 bits. Thus D
Since the number of bits of the A-converter 26 is smaller than the number of bits of the A / D converter 24, conversion must be performed so that the MSB bit of the A / D converter always stands at the MSB of the 12-bit digital value at the time of DA conversion. Therefore, when the numerical value of the AD-converted digital signal is small, the numerical value of the blank in the upper digit is omitted, and the effective numerical value is represented by a value close to full scale. When the value of the digital signal after AD conversion is large, the principle that a bit always stands at the MSB of the 12-bit digital value does not change.
In this case, the lower-order bit is truncated and becomes the input of the DA converter 26.

The output of the DA converter 26 is input to the analog recording device 23, and the waveform of the earthquake is output. In order to detect the switching value of this waveform, the sensitivity is switched. The output of the signal DA converter 27 is input to the analog recording device 23. The sensitivity switching signal DA converter 27 is input from the information processing device 25 which level the sensitivity switching value is, converts a digital value indicating the level into an analog signal, and simultaneously converts the vibration waveform into an analog signal. Record on a recording device. The analog recording device 23 receives a timing signal from a timing device 28 and records the time axis of the vibration. To save tracks of the analog recording device, the output of the D / A converter 27 for the sensitivity switching signal is saved. And an output of the timer 28 is added by the adder 29 and a superimposed signal is input.

In this way, an appropriate effective numerical value is always expressed as a value close to full scale, and the level of sensitivity switching is recorded at the same time. AD converter 24 and DA
Since the difference in the number of bits of the converter 26 is 4 bits, the switching ratio of the two is 16-times scale, the output value of the amplifier 22 is adjusted in sensitivity by 16 times scale, and the output from the DA converter 26 is output. Is always a measured value close to full scale, and the level of the switching value is also
Is output to In addition, the measured value can be expressed in logarithm,
Also, since the measured value converted into a form convenient for processing by the information processing device is DA-converted and displayed / recorded, it can be selected and used according to the purpose.

Although this embodiment has been described with reference to an example of an earthquake observation device, it goes without saying that the object can be similarly achieved when applied to a general vibration measurement device other than the earthquake observation device. In the present embodiment, the sensitivity switching signal D
Although the sensitivity switching level is recorded by using the A converter, the sensitivity switching level may be detected by other means without depending on the sensitivity switching signal DA converter. It does not necessarily have to be superimposed on the sensitivity switching signal. Further, in the present embodiment, when the sensitivity is switched, the MSB bit of the AD converter is always set at the MSB digit of the digital value of the DA converter. , The number of switching stages may be reduced as appropriate, including the case where a bit is set in the next digit of the MSB.

[0018]

As described above, according to the present invention, a circuit such as a switch for changing a gain is not required unlike the conventional sensitivity adjusting device, and the device is simplified and maintenance is easy. In addition, recording can be performed continuously from a minute vibration to a vibration having a large amplitude, and there is an effect that an offset due to gain switching does not occur and stable recording can be performed. Further, according to the invention of the present application, the measured value can be converted by the information processing device, so that an appropriate effective numerical value is represented by a value close to full scale, and the level of sensitivity switching is also recorded at the same time, which is convenient for observation. Yes, it can also be expressed on a logarithmic scale, and of course linear recording is possible, so that it is possible to select and record as needed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of the present invention.

FIG. 2 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 3 is a block diagram including a partial circuit diagram of a vibration recording device having a conventional analog gain switching device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Vibration sensor 12 Amplifier 13 Analog recording device 14 AD converter 15 Information processing device 16 DA converter

Claims (1)

(57) [Scope of request for utility model registration] 1. A vibration measuring device for amplifying a detection value from a vibration sensor by an amplifier and recording the amplified value in an analog recording device, wherein the AD converter converts an output from the amplifier into a digital signal.
A converter, an information processing device that reads a signal from the AD converter and instructs switching of sensitivity in accordance with the level of the read value and converts the read value, and a bit number smaller than the number of bits of the AD converter. D that converts the output value of the information processing device into an analog signal
A converter and a sensitivity switching signal from the information processing device,
The analog type recording apparatus for outputting as an analog signal
And a D / A converter for a sensitivity switching signal to be input to the vibrometer.