JP2008122291A - Physical quantity change measuring device, physical quantity change measuring method, program for measuring physical quantity change, and recording medium recording the program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a physical quantity change measuring device for performing highly accurate quantization without narrowing a measuring range. <P>SOLUTION: The physical quantity change measuring device includes: a first digital conversion processing part 30 for converting one voltage signal 11a corresponding to the change of a physical quantity into a first digital signal; an analog conversion processing part 31 for converting it into a first analog signal; a subtraction processing part 40 for outputting a subtraction signal 40a subtracting the first analog signal 31a from the other voltage signal 11b; a second amplification part 41 for outputting a signal 41a by enlarging the subtraction signal 40a; a second digital conversion processing part 70 for converting the signal 41a into a second digital signal 70a; and an addition processing part 80 for outputting an output signal 80a adding the second digital signal 70a and the first enlarged digital signal 32a. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a physical quantity change measuring device and the like.
For example, the present invention relates to a physical quantity change measuring apparatus, method, program, and recording medium for recording a program for measuring a physical quantity with high accuracy.

Measurement devices that measure physical quantities such as displacement, velocity, acceleration, sound, light (image), electromagnetics, and temperature are known, and measurement devices that improve measurement accuracy using digital signal processing technology are known (For example, Patent Document 1).
Such a measuring apparatus includes a sensor that outputs a potential change according to a change in physical quantity, and a digital conversion processing unit that converts an output signal of the sensor into digital data.

The digital conversion processing unit includes a low-pass filter that removes the excitation frequency component of the displacement sensor, and an A / D converter that converts the voltage value at each sampling time into a numerical value with a predetermined resolution.
In such a measurement apparatus, a physical quantity change (for example, displacement) is detected by a sensor, and a signal having a potential change corresponding to the physical quantity change is output from the sensor.
This signal is input to the digital conversion processing unit, passes through a low-pass filter, and is AD converted by the A / D conversion unit. Then, the detection result by the sensor is obtained as digital data. The measurement data obtained as digital data in this way may be digitally displayed on a predetermined display unit, or may be used for further analysis of measurement results.

  In order to improve the measurement resolution of such a measuring apparatus, the output signal from the sensor is enlarged. For example, when the output signal from the sensor is doubled, the potential change amount of the signal is doubled with respect to the change of the physical quantity to be measured. Then, since the sensitivity to displacement is doubled, the detection sensitivity is increased, and a slight change in physical quantity can be detected with high resolution.

JP 2005-241549 A

However, the A / D converter has a dynamic range (voltage detection range), and there is a problem that the width of the voltage value that can be input to the A / D converter is predetermined.
That is, when the input signal exceeds the dynamic range of the A / D converter and overflows, there is a problem that accurate quantization is not performed with respect to a change in physical quantity during the overflow period.
For example, if the signal is simply doubled, the measurable area is halved due to the dynamic range of the A / D converter.
As described above, the conventional measuring apparatus cannot perform high-resolution measurement in a wide measurable region.

  An object of the present invention is to provide a physical quantity change measuring apparatus, method, program, and recording medium on which this program is recorded, which can perform high-resolution measurement in a wide measurable region.

  The present invention inputs an analog voltage signal corresponding to a change in a physical quantity detected by a sensor and inputs the voltage signal into two systems, and converts one voltage signal divided into the two systems into a digital signal. A first digital conversion processing unit that converts and outputs a first digital signal; an analog conversion processing unit that converts the first digital signal into an analog signal and outputs a first analog signal; and the two systems A subtraction processing unit that outputs a subtracted signal obtained by subtracting the first analog signal from the other voltage signal divided into a first enlarged signal that expands the first digital signal and outputs a first enlarged signal. A second enlargement processing unit for enlarging the subtraction signal and outputting a second enlargement signal; and a second for converting the second enlargement signal into a digital signal and outputting a second digital signal. Digital A conversion processing unit, characterized by comprising an adding unit which outputs an output signal obtained by adding the second digital signal and the first expansion signal.

Here, the input unit may be configured to branch the voltage signal of a single sensor into two systems, or may be configured to input the voltage signals of two sensors to input into two systems. As the input unit, in the case of a single sensor, a branching unit that branches an input signal into two systems can be exemplified.
The first digital conversion processing unit and the analog conversion processing unit extract an analog signal for subtraction from one voltage signal of the sensor.
The voltage signal corresponding to the sensor output is considered to be an addition of a large amplitude component having a large amplitude corresponding to a large change in physical quantity and a small amplitude component having a small amplitude corresponding to a small change in physical quantity. The first digital conversion processing unit and the analog conversion processing unit extract signal components in which the amplitude of the voltage signal is greater than a certain width. For this reason, a large amplitude signal can be given as an example of the first analog signal. Subtracting the large amplitude component from the sensor output voltage signal results in a small amplitude component.
The subtraction processing unit subtracts the first analog signal that is an analog signal from the voltage signal of the input unit that is an analog signal. This subtraction can be realized by an operational amplifier, for example.
The first enlargement processing unit enlarges the first digital signal and outputs a first enlarged signal. The first expansion processing unit can perform value expansion by digital signal processing. The second enlargement processing unit enlarges the subtraction signal and outputs a second enlargement signal. This expansion can be an amplification of an analog signal, for example using a transistor. The first digital conversion processing unit converts the second enlarged signal, which is an analog signal, into a digital signal.
As these digital conversion processing units, for example, a combination of a low-pass filter and an A / D converter can be cited as an example.
The addition processing unit adds digital signals. The second digital signal is a digital signal obtained by quantizing (digitizing) an analog signal obtained by enlarging (amplifying) a subtraction signal (for example, a small amplitude component). The first enlarged signal is a digital signal obtained by quantizing the voltage signal from the sensor (for example, a large amplitude component) and expanding it. The addition processing unit expands, for example, a digital signal having a large amplitude component, and adds the expanded digital signal and a digital signal having a small amplitude component, for example. This addition may be performed by a logic circuit or a combination of a CPU, a memory, and a program.

  According to such a configuration, the voltage signal corresponding to the change in the physical quantity of the object to be measured is divided into two systems, and one voltage signal becomes the first digital signal and the first analog signal for subtraction. . Then, the subtraction processing unit subtracts the first analog signal from the other voltage signal to extract, for example, a small amplitude signal. In the present invention, this subtraction signal is enlarged and subjected to digital conversion processing, whereby measurement with high resolution is performed with respect to quantization. The digital signal obtained by quantizing the subtraction signal with high resolution (high resolution) is in an amplified state with respect to the physical quantity. However, since the entire voltage signal of the sensor or the like is not enlarged but the subtraction signal (for example, a small amplitude component) is enlarged, the resolution is improved without narrowing the measurement range. The measurement range is the magnitude of the voltage signal input from the sensor and the magnitude of the change in the physical quantity of the object to be measured. Further, the first digital signal is enlarged by the first enlargement processing unit. Then, the addition processing unit adds the second digital signal that is the enlarged subtraction signal and the enlarged first enlarged signal.

In the present invention, the first digital conversion processing unit converts one voltage signal into a digital signal. For example, quantization is performed with the number of quantum bits q ₁ . The analog conversion processing unit converts this digital signal into an analog signal. This first analog signal, a small small-amplitude component of an amplitude which can not be quantized unless higher resolution than the resolution of the quantum bits q ₁ (or height) is not included, a large a large amplitude component of the amplitude (or height) It becomes only. The small amplitude component is a component corresponding to a small change in physical quantity (for example, displacement), and the large amplitude component is a component corresponding to a large change in physical quantity. That is, the large and small amplitude components are components that focus on the magnitude of the voltage signal, not components that focus on the frequency.
The subtraction processing unit subtracts the first analog signal including only the large amplitude component from the other voltage signal. Then, a subtraction signal (analog signal) of a small amplitude component that is not quantized with the number of qubits q ₁ is extracted.

In the present invention, each of the voltage signals divided into two systems is used to extract a large amplitude component from one voltage signal and subtract it from the other voltage signal to extract a subtraction signal that is a small amplitude component. can do. In extracting this small amplitude component, the measurement range is not narrowed.
Further, the small amplitude component is expanded, and the expanded voltage signal is converted into digital data (second digital signal). Measurements with high resolution can be obtained by the quantization after the enlargement. Thereby, it is possible to perform measurement with high resolution without narrowing the measurement range.

In the present invention, the same signal (subtraction is an analog signal and addition is a digital signal) of the sensor and the first digital conversion processing unit is used for subtraction of the subtraction processing unit and addition of the addition processing unit. Adjustment according to device characteristics, such as 1 digital conversion processing part, is unnecessary.
If the enlargement ratio in the first enlargement processing section (digital enlargement) and the enlargement ratio in the second enlargement processing section (analog amplification) are the same ratio, the accurate and high resolution can be obtained. It can be a measurement. In addition, the accuracy can be improved by finely adjusting the enlargement ratio of both in accordance with the result of calibration.

In the present invention, the center position of the subtraction signal becomes close to the center position of the voltage detection range by subtraction of the subtraction processing unit without performing the work of matching the center position of the physical quantity change to the center position of the voltage detection range. A minute change within the measurement range can be amplified and measured with high accuracy. Therefore, when measuring the physical quantity, it is possible to dispense with difficult and complicated operations such as alignment for aligning the centers.
In the present invention, since the digital conversion processing unit is used efficiently, the resolution can be increased in the same measurement range as the conventional one, and the measurement range can be expanded while maintaining the same resolution as the conventional one.
Thus, according to the present invention, the resolution can be increased without narrowing the measurement range.

Furthermore, in the present invention, the first digital conversion processing unit converts the voltage signal of the sensor into a digital signal with a predetermined number of bits q ₁ , and the analog conversion processing unit converts this into a first analog signal. Thus, the small amplitude component which is not quantized with the quantization bit number q ₁ can be removed, and the large amplitude component can be extracted. Therefore, it is possible to extract a large amplitude component regardless of the frequency of the input voltage signal.
Since the addition is performed with a digital signal, the numerical value of the second digital signal corresponding to the amplitude of the large amplitude component is used regardless of the dynamic range (voltage detection range) of the second digital conversion processing unit. Can be enlarged. Accordingly, it is possible to obtain a digital signal obtained by adding the original large amplitude component with a resolution obtained by amplifying the small amplitude component without narrowing the measurement range.

In the present invention, based on the resolution of the first digital conversion unit, it is preferable to set the magnification factor n ₂ of the first expansion coefficient of the enlargement processing unit of n ₁ and the second enlargement processing section .
Here, n ₁ and n ₂ are easy to handle if they are equal units in dimensionless multiples. If the units are equal and n ₁ and n ₂ are the same, high-resolution measurement can be performed.

In this invention, it is preferable to provide the synchronous process part which synchronizes the two said branched signals based on the period of the drive signal which drives the said sensor.
The synchronization processing unit may be a process of delaying the processing of the subtraction processing unit using the drive signal as a synchronization signal.

  According to such a configuration, delay dispersion (variation) is allowed for the processing of the first digital conversion unit and the analog conversion unit, so that more advanced signal processing can be performed.

  The physical quantity change measuring method of the present invention includes a sensor process for measuring a change quantity of a physical quantity of an object to be measured and outputting an analog voltage signal corresponding to the change quantity, and an input process for dividing the voltage signal into two systems. A first digital conversion processing step of converting one of the voltage signals divided into the two systems into a digital signal and outputting a first digital signal, and converting the first digital signal into an analog signal into a first signal A first analog conversion processing step for outputting the analog signal, a first analog subtraction step for outputting a subtraction signal obtained by subtracting the first analog signal from the other voltage signal divided into the two systems, A first enlargement processing step of enlarging the first digital signal and outputting a first enlargement signal; a second enlargement processing step of enlarging the subtraction signal and outputting a second enlargement signal; Expansion of 2 A second digital conversion processing step of converting the signal into a digital signal and outputting a second digital signal; and an addition processing step of outputting an output signal obtained by adding the second digital signal and the first enlarged signal; , Provided.

The physical quantity change measurement program of the present invention is a program for measuring a change in physical quantity using a physical quantity change measuring device. This physical quantity change measuring device is divided into two systems as hardware resources, an analog voltage signal corresponding to the change in the physical quantity detected by the sensor is input and the voltage signal is divided into two systems. A first digital conversion processing unit that converts the other voltage signal into a digital signal and outputs the first digital signal; and converts the first digital signal into an analog signal and outputs the first analog signal. An analog conversion processing unit, a subtraction processing unit for outputting a subtraction signal obtained by subtracting the first analog signal from the other voltage signal divided into the two systems, and amplifying the amplitude of the subtraction signal by n ₁ times An amplifying unit for outputting a second enlarged signal; a second digital conversion processing unit for converting the second enlarged signal into a digital signal and outputting a second digital signal; Comprises a memory for storing a digital signal as data, CPU functioning as the predetermined expansion portion by processing the data stored in the memory installed together in the memory, and.
Then, the physical quantity change measurement program stores, in the CPU, a first setting procedure for setting the gain n _{1 of the} amplification unit and a second setting procedure for setting the expansion coefficient n ₂ of the expansion unit. And an enlargement procedure for enlarging the first digital signal output from the first digital conversion processing unit by n ₂ times to output a first enlarged signal, and an enlargement procedure according to the enlargement procedure An addition procedure for outputting an output signal obtained by adding the first enlarged signal and the second digital signal is executed.

Here, each procedure executed by the CPU may be a function realized by the CPU. Each procedure, that is, the first setting procedure, the second setting procedure, the enlargement procedure, and the adding procedure is calculated and controlled by logical operation in accordance with inputs and operations from an input means such as a keyboard and a pointing device connected to the CPU. I do.
The enlargement procedure corresponds to the first enlargement processing unit described above, and the addition procedure corresponds to the addition processing unit.

  The recording medium recording the physical quantity change measurement program of the present invention is a recording medium for recording the program and installing the program file in an auxiliary storage device such as a hard disk connected to the CPU. Examples of the recording medium include optical disks such as CD and DVD. In this example, an optical disk drive (recording medium reader) is provided in the CPU, and a program is installed from the reader into the auxiliary storage device. The program or its file may be transmitted by wired or wireless communication via a network such as the Internet or a LAN, and supplied to a computer including a CPU for installation. In this case, the contents of the digital signal processing can be updated afterwards without changing the hardware resources of the physical quantity change measuring device.

Further, since the program is configured to cause the CPU to implement each procedure or function, the parameters (n ₁ , n ₂ ) in each procedure are easily changed according to the input from the input means or a predetermined measurement mode. be able to. For this reason, it is possible to switch between measurement for obtaining a high resolution while keeping the measurement range constant and measurement for obtaining a wide measurement range while keeping the resolution constant while using the same digital conversion processing unit.

The physical quantity change measuring device of the present invention also includes a first displacement sensor that detects a change in the physical quantity of the object to be measured and outputs a voltage signal corresponding to the change in the physical quantity, and a change in the physical quantity of the object to be measured. And a second displacement sensor that outputs a voltage signal having an amplitude corresponding to the change in the physical quantity, and a voltage signal of the second displacement sensor is converted into a digital signal and a first digital signal is output. 1 digital conversion processing unit, an analog conversion processing unit for converting the first digital signal into an analog signal and outputting the first analog signal, and a first enlarged signal by expanding the first digital signal , A subtraction processing unit that subtracts the first analog signal from the voltage signal of the first displacement sensor and outputs a subtraction signal, and expands the subtraction signal to a second Expanded signal A second enlargement processing unit for outputting, a second digital conversion processing unit for converting the second enlarged signal into a digital signal and outputting the second digital signal, and the second digital signal and the first enlarged signal. And an addition processing unit that outputs an output signal obtained by adding the two.
Here, since the first and second sensors respectively measure the change in the physical quantity of the object to be measured and output the input voltage, the branching to the two systems by the input unit described above is here from each sensor. Corresponds to the voltage signal.

  According to such a configuration, the resolution can be increased without narrowing the measurement range by analog subtraction and digital addition using the output of the first displacement sensor and the output of the second displacement sensor. .

In the present invention, it is preferable that the second sensor is installed at a position where the displacement is 1 / m compared to the displacement measured by the first sensor.
For this reason, the potential change of the second sensor is 1 / m of the potential change of the first sensor. Therefore, the measurement range of the second sensor can be widened, or a sensor with a narrow measurement range can be used.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the reference numerals assigned to the elements in the drawings.

(First embodiment)
FIG. 1 shows the configuration of an embodiment of the physical quantity change measuring apparatus of the present invention. The physical quantity change measuring device according to the present embodiment inputs analog voltage signals 11a and 11b corresponding to changes in physical quantity detected by a sensor 10 (for example, a displacement sensor) and divides this voltage signal into two systems. And the first digital signal of the first digital signal processing unit 30 that converts the one voltage signal 11a divided into the two systems into a digital signal and outputs the first digital signal 30a, and converts the first digital signal into an analog signal. An analog conversion processing unit 31 that converts and outputs the first analog signal 31a, and a subtraction process that outputs a subtraction signal 40a obtained by subtracting the first analog signal 31a from the other voltage signal 11b divided into the two systems Part 40.
The physical quantity change measuring device further enlarges (amplifies) the first enlargement processing unit (enlargement unit) 32 that enlarges the first digital signal 30a and outputs the first enlargement signal 32a, and the subtraction signal 40a. A second enlargement processing unit (amplification unit) 41 for outputting the second enlarged signal 41a, and a second output unit for converting the second enlarged signal 41a into a digital signal and outputting the second digital signal 70a. A digital conversion processing unit 70, and an addition processing unit 80 that outputs an output signal 80a obtained by adding the second digital signal 70a and the first enlarged signal 32a are provided.

In the present embodiment, it is assumed that the sensor 10 measures a change in physical quantity and outputs a voltage signal that changes in potential according to the magnitude of the change. Physical quantities include displacement, speed, acceleration, sound, light (image), electromagnetics, temperature, and the like. A configuration in which the sensor 10 is a displacement sensor will be described later as an example.
The input unit 20 branches the potential change of the sensor 10 into two systems. One voltage signal 11 a is input to the first digital conversion processing unit 30, and the other voltage signal 11 b is input to the subtraction processing unit 40.
The analog conversion processing unit 31 extracts a large amplitude component from the voltage signal 11b by converting the first digital signal into an analog signal. That is, the analog signal 31a having only the large amplitude component excluding the small amplitude component that cannot be quantized by the qubit q1 of the _first digital conversion processing unit is extracted. Here, this analog signal is referred to as a first analog signal in distinction from other analog signals (second enlarged signal or the like).
The subtraction processing unit 40 obtains the small amplitude component 40a by subtracting the large amplitude component from the voltage signal 11b of the sensor 10. The subtraction processing unit 4 may be an addition processing unit that inverts and adds the first analog signal from the analog conversion processing unit 31 instead of subtraction. The digital conversion processing unit 70 amplifies the subtraction signal 40a composed of the small amplitude component by n ₁ times and then quantizes it with a resolution q ₂ . Then, the enlargement unit 6 enlarges the first enlarged signal 32a composed of the large amplitude component by n ₂ times, and the addition processing unit 8 adds the _second enlarged digital signal that is the small amplitude component. Thereby, a high-resolution digital signal is obtained without narrowing the measurement range.

  As shown in FIG. 2, the sensor 10 outputs a potential change corresponding to a change in physical quantity. In the measurement range 1, as indicated by the dotted line 1a, a change in the range of the measurement range 1 is detected in the entire voltage detection range. In order to increase the physical quantity detection resolution while keeping the voltage detection range of the digital conversion processing unit 30 constant, as shown by the solid line 1b, the change in the measurement range 2 narrower than the measurement range 1 is measured. . This solid line 1b is obtained by expanding the range 1c of the measurement range 2 of the dotted line 1a to the voltage detection range and extending it in the vertical direction in the figure.

  In other words, the sensor 10 that generates an output in which the voltage signal is proportional to the change in the physical quantity of the object to be measured can increase the detection sensitivity (quantization resolution) by subjecting the voltage signal to electrical signal expansion processing. . For example, when the output voltage is doubled by the enlargement process, the sensitivity to displacement is doubled. When a voltage value is read by digital conversion at the subsequent stage of a signal in which a change in physical quantity such as displacement is expanded, if the voltage reading resolution of the digital conversion element (A / D converter) is the same, the sensitivity is doubled. Then, a change in physical quantity can be detected with a resolution twice as high. Thus, when the voltage signal of the sensor 10 is multiplied by n without changing the number of bits (resolution) of the A / D converter, the input displacement can be detected with high accuracy of n times.

As shown in FIG. 3, the physical quantity change measurement device according to the present embodiment, measured in the range of the measurement range 1, to amplify and expand small-amplitude components 4a removing the large amplitude component is quantized with a resolution q ₂ that Thus, a digital signal with high resolution can be obtained while the measurement range 1 is set. That is, originally, the measurement range has to be a narrow range indicated by reference numeral 7a. In this embodiment, the small amplitude component 4a is amplified and quantized, so that the resolution q is maintained while maintaining the range of the measurement range 1. By quantizing the small amplitude component in ₂ and adding it to the large amplitude component, measurement with high resolution can be performed.

FIG. 4 shows an outline of the output signal 80a of this embodiment.
Reference numeral 30 a is a first digital signal obtained by quantizing the voltage signal from the sensor 10 by the first digital conversion processing unit 30. Reference numeral 32 a is a first enlarged signal obtained by enlarging the first digital signal by n ₂ times with the enlargement unit 32. In the example shown in FIG. 4, the enlargement factor n ₂ depends on the qubit q _{1 and the} like of the first digital conversion processing unit 30, although for the convenience of illustration, the enlargement is three times larger and the smaller enlargement. The value of the first enlarged signal is quantized and enlarged to the discrete value indicated by the horizontal solid line.
Reference numeral 70a is obtained by quantizing the second enlarged signal obtained by enlarging the subtraction signal 40a by n ₁ times by the second digital conversion processing unit. The value of the second digital signal indicated by reference numeral 70a is positive, and the value of the second digital signal 70a indicated by reference numeral 70a1 in FIG. 4 is negative.
Reference numeral 80 a is an output signal obtained by adding the first digital signal 32 a and the second enlarged signal by the addition processing unit 80.

The first digital signal on the left side in FIG. 4 has a quantization stage of 2 to the q ₁ power with respect to 10 [V] which is the voltage detection range of the first digital conversion processing unit 30. For example, if the quantization bit is 4 bits, the number of quantization steps is 2 to the 4th power and 16 steps. The actual value is 0 to 15 (the maximum value in the figure is minus 1). When the first digital signal and the subtraction signal are enlarged and amplified by n ₁ = n ₂ times, the quantization stage becomes 2 (q ₁ + q ₂ ) power. Thereby, the final resolution of the present embodiment is increased. When the voltage detection range corresponding to the right side in FIG. 4 is shown, the range is much narrower than the quantization stage. That is, in this embodiment, it is possible to perform measurement with high resolution using a small voltage detection range by signal processing.

As shown in FIG. 4, the resolution in this embodiment is q ₁ + q ₂ bits. For example, when the resolution q _{1 of} the first digital conversion processing unit 30 is 4 bits (16 steps) and the second digital conversion processing unit 70 is capable of 8 bits (256 steps), the physical quantity change of this embodiment The final resolution of the measuring device is 4 + 8 = 12 bits and 16 × 256 = 4096 steps. At this time, if the voltage detection range is 10 [V], the 4-bit resolution (minimum detection range 30b) is 10 [V] /16=0.625 [V]. The amplifying unit 41 amplifies the subtraction signal 40a having a wave height (twice the amplitude) within 0.625 [V] which is the minimum detection range 30b to obtain a second enlarged signal 41a, and the second digital conversion processing unit 70 The second enlarged signal 41a is quantized into a second digital signal 70a. For this reason, the resolution obtained by adding the resolution q2 of the second digital conversion processing unit to the resolution q1 of the _first digital conversion processing unit 30 is the final resolution.

In the example the maximum height that allows the design of the subtraction signal 40a 2 times the minimum of the voltage detection width by resolution q ₁ (1 bit) or less, the signal processing according to this embodiment, bit q ₁ + q ₂ -1 Quantization with numbers. When q ₁ is 4 bits and q ₂ is 8 bits, the resolution is 11 bits.

In the example the pulse height of the subtraction signal 40a is small-amplitude components, schedule twice (1 bit) within the minimum voltage detection width resolution q _1, the maximum voltage of small amplitude components, 0.625 [V] × 2 = 1.25 [V]. A multiple of the assumed maximum amplitude (wave height) with respect to this minimum voltage detection width is referred to as a small amplitude coefficient.
In the example in which the small amplitude coefficient is doubled, 10 [V] /1.25 [V] = 8, and the small amplitude component can be multiplied by 8. That is, it is possible to expand 4 [bits] -1 [bits] = 3 bits (8 steps). This 1 [bit] to be subtracted is a bit display of a small amplitude coefficient. When the small amplitude coefficient is set to 2 times or more, when the subtraction signal 40a has a plus value and a minus value, the plus side minimum detection width and the minus side minimum detection width are used with a margin. And can be amplified.

When the resolution q _{1 of} the first digital conversion processing unit 30 is 8 bits and 256 levels, dividing the voltage detection range by the resolution yields 10 [V] /256=0.039 [V].
If small amplitude coefficient is 1, the wave height of the subtraction signal is equal to or less than the minimum detection range 30b by the resolution q _1.
10 [V] /0.039 [V] = 256 times That is, when the small amplitude coefficient is 1 time and q ₁ is 8 bits, it can be 256 times, which is 8 [bits] 8 bits (256 steps). ).
If small amplitude factor is 2, the wave height of the subtraction signal is less than twice the minimum detection range 30b by the resolution q _1.
0.039 [V] x 2 = 0.078 [V]
10 [V] /0.078 [V] = 128 times That is, when q ₁ is 8 bits, it can be 128 times.
8 [bits] -1 [bits] = 7 bits (128 steps) can be expanded.

  As described above, according to the present embodiment, the first digital conversion processing unit 30 and the analog conversion processing unit 31 extract the large amplitude component (first analog signal 31a) and subtract it from the voltage signal 11a of the sensor 10. Thus, since the small amplitude component subtraction signal 40a is obtained and the small amplitude component subtraction signal 40a is amplified and converted into a digital signal, high resolution measurement can be performed without narrowing the measurement range 1.

(Example 1)
Next, the physical quantity change measuring apparatus (displacement measuring apparatus) according to the first embodiment will be described.
Referring to FIG. 1 again, the first embodiment employs a displacement sensor 10 as a sensor. The displacement measuring apparatus measures the amount of displacement of the object to be measured and outputs a voltage signal having an amplitude corresponding to the amount of displacement, and a smoothing unit 11 that smoothes the output signal of the displacement sensor 10. And.

  As shown in FIG. 5, in this embodiment, a differential transformer is employed as the displacement sensor 10. There are various types of differential transformers, but as a basic configuration, an oscillation circuit 13 that oscillates using a constant frequency AC voltage serving as a carrier signal as an excitation signal 10a, and a primary to which this AC voltage is applied. Between the coil 12, the secondary coil 14 having two coils, generating an induced voltage in response to excitation of the primary coil, and outputting the voltage difference of the differential coupling, and the primary coil 12 and the secondary coil 14. And a movable iron core 15 that moves in parallel with the coil following the change in the physical quantity. The displacement sensor 10 has a contact 16 that rotates about a central axis 17 following the height of the surface of the object to be measured.

When the movable iron core moves from the center position by the rotation of the contact 16 following the surface height of the object to be measured and pivoting about the center axis 17, a difference occurs in the induced voltages of the upper and lower coils of the secondary coil 14, An AC voltage proportional to the difference appears. The phase of the AC voltage changes according to the vertical direction from the center position. The differential transformer uses the properties of the movable iron core and the secondary coil to output AC signals 10b and 10c whose amplitude changes according to the operation of the movable iron core. When the state shown in FIG. 5A changes to the state shown in FIG. 5B, the amplitude of the AC signal 10b of the secondary coil 14 changes to the amplitude of 10c. The displacement sensor 10 converts the AC signals 10 a and 10 b into a potential change corresponding to the amount of displacement and outputs the change to the smoothing unit 11.
The temporal tracking performance of the displacement sensor 10 is determined by the frequency of the excitation signal 10a of the oscillation circuit 13.
The smoothing unit 11 performs smoothing by removing the carrier signal 10a and removing high frequency components. As a result, a potential change (displacement signal) proportional to the amount of displacement is output. The input unit 20 branches the output signal of the smoothing unit 11 into two systems.

FIG. 6 shows an example of each signal in the first embodiment. In this example, the following settings are used.
・ Measurable range of displacement sensor: ± 500 [μm]
・ Signal amplitude after smoothing: ± 5 [V]
-Dynamic range of the first and second digital conversion processing: ± 5 [V]
-Resolution of the first digital conversion process 4 bits (16 steps): 0.625 [V]
-Resolution of the second digital conversion process 8 bits (256 steps): 0.04 [V]

  As shown in FIG. 6A, the smoothing unit 11 outputs a displacement signal (potential change). That is, the displacement signal detected by the displacement sensor 10 is smoothed by the smoothing unit 11 and converted into a displacement signal 11a in which displacement and voltage are proportional. The signal 11a varies between ± 5 [V]. The displacement signal 11 a output from the smoothing unit 11 is branched into two systems. One displacement signal 11 a is sent to the first digital conversion processing unit 30, and the other displacement signal 11 b is sent to the subtraction processing unit 40. In the example of this signal, the amplitude is already close to the dynamic range ± 5 [V] of the first digital conversion processing unit 30 in the subsequent stage. Therefore, the displacement cannot be expanded as it is, and high resolution signal processing is performed. Can not do.

The displacement signal 11a sent to the first digital conversion processing unit 30 is converted into a digital signal 30a at this time, as shown in FIG. 6B.
In this example, the quantization resolution q ₁ of the first digital conversion processing unit 30 is set relatively low, and the input dynamic range is set to a range as wide as the sensor dynamic range.
Here, a small amplitude component having a resolution of 0.625 [V] or less is not detected, and a quantized digital signal 30a (large amplitude component) as shown in FIG. 6C is obtained.

This signal is divided into two systems, one of which is converted again into the analog signal 31a in the analog conversion processing unit 31 at the subsequent stage. The other is sent to the addition processing unit 80 after coefficient processing in the enlargement unit 32.
A signal 11b sent from the smoothing unit 11 to the subtraction processing unit 40 and a signal 31a sent from the smoothing unit 11 to the subtraction processing unit 40 via the first digital conversion processing unit 30 and the analog conversion processing unit 31. The subtraction processing unit 40 performs a subtraction operation.
The signal 31a quantized and analog-converted by the first digital conversion processing unit is subtracted from the original signal 11b, and a signal (small amplitude component) 40a shown in FIG. 6D is obtained.
This signal 40 a is a small amplitude fluctuation component of 0.625 (× 2) [V] or less that has not been detected by the digital conversion processing unit 30.
This “(× 2)” is the small amplitude coefficient.

  The analog signal 40a of the small amplitude component that has passed through the subtraction processing unit 40 is amplified in amplitude by the amplification unit 41, and becomes an analog signal 41a shown in FIG. Since the original signal 11b has an amplitude close to the dynamic range of the digital conversion process, the amplitude cannot be expanded as it is, but the subtracted analog signal 41a has a sufficiently smaller amplitude than the dynamic range. The displacement can be enlarged.

In this example, since the quantization resolution q ₁ by the digital conversion processing unit is 0.625 [V], the signal after the subtraction processing has a resolution of 0.625 [V] (twice (1.25 [V])) or less. Has an amplitude component. Since the dynamic range of the first digital conversion processing unit 30 is ± 5 [V], the displacement can be expanded up to 16 times (8 times) at the maximum. That is, the maximum amplification factor n ₁ in the first embodiment can be calculated and set by the resolution q ₁ of the first digital conversion processing unit and the voltage detection range of the first digital conversion processing unit. .

  The second digital conversion processing unit 70 quantizes the second enlarged signal 41a in which the displacement has been amplified to obtain a second digital signal. The first digital signal 32 a that has passed through the first digital conversion processing unit 30 and the expansion unit 32 and the second digital signal 70 a output from the second digital conversion processing unit 70 are added by the addition processing unit 80. Are again combined into one signal. In the example shown in FIG. 6F, the sampling rate corresponding to the lateral resolution in the drawing is different for the first digital signal and the second digital signal, but they may be the same. When the sampling rates are different, moving average processing or the like for matching the sampling rates of both digital signals 32a and 70a is performed before the addition processing unit 80.

Since the first digital conversion processing unit 30 and the second digital conversion processing unit 70 have different qubits (voltage resolution), if the output values are added as they are, the scale differs between the small amplitude component and the large amplitude component. End up. In normal measurement, the enlargement unit 32 performs a coefficient process of multiplying n ₂ to make the two signals equivalent. FIG. 6F shows a digital signal in which both are equivalent, that is, n ₁ and n ₂ are equalized and added. This added signal has a wide measurement range and high resolution information, and the displacement signal of the displacement sensor 10 can be detected with higher accuracy.

  In this example, since the resolution of the first digital conversion processing unit 30 and the second digital conversion processing unit 70 is 4 bits and 8 bits, respectively, the measurable range ± 500 [μm] of the displacement sensor 10 is This is equivalent to detection with a resolution of 12 bits (11 bits) without a decrease in the measurement range. If the original signal is subjected to displacement expansion as it is and displacement detection is performed with a resolution of 12 bits (11 bits), the measurable range of the displacement sensor becomes narrower in inverse proportion to the signal expansion, and the small amplitude coefficient is set to 2 [ Double], only a measurement range of 500 [μm] / 8 [times] = ± 62 [μm] can be obtained.

As described above, in Example 1 or the like, the gain n ₁ of the amplification unit 41 and the expansion coefficient n ₂ of the expansion unit 32 are set based on the resolution q ₁ of the first digital conversion processing unit 30. . In normal measurement, n ₁ = n ₂ .

As described above, in the apparatus according to the first embodiment, the voltage signal of the displacement sensor that generates the voltage signal proportional to the input displacement is separated into the large amplitude component and the small amplitude component, and the small amplitude component is amplified and quantized, Since it is then added to the enlarged digital signal of the large amplitude component, it is possible to realize high resolution signal processing by enlarging the displacement without lowering the measurement range.
Conventionally, in order to realize high-resolution and high-accuracy measurement, it has been necessary to perform exact alignment of the object to be measured, but the work load is greatly reduced.

(Example 2)
Next, Example 2 will be described. Example 2 discloses Example 1 as a method. A physical quantity change measuring device program (displacement measuring device program) and its recording medium will be described.

In FIG. 7, the structural example of the displacement measuring method of the present Example 2 is shown.
First, the displacement sensor 10 measures a change in the physical quantity of the object to be measured and outputs voltage signals (displacement signals 11a and 11b) having an amplitude corresponding to the displacement shown in FIG. 8A (step S1, S1). Sensor process). Subsequently, the input unit 20 branches the voltage signals 11a and 11b into two systems (step S2, input process). Further, the first digital conversion processing unit 30 converts one voltage signal 11a from the input step S2 into a first digital signal 30a shown in FIG. 8B (step S3, first digital conversion processing). Process). Subsequently, the analog conversion processing unit 31 converts the first digital signal 30a into an analog signal, thereby generating a first analog signal (large amplitude component signal) 31a shown in FIG. S4, analog conversion processing step).

Then, as shown in FIG. 8C, the subtraction processing unit 40 subtracts the large amplitude component signal 31a from the other voltage signal 11b of the input step S2 (step S5, analog subtraction step). By this subtraction, an analog signal (subtraction signal) 40a having a small amplitude component shown in FIG. 8D is obtained. Subsequently, the amplitude of the subtraction signal 40a from the analog subtraction step S5 is amplified by n ₁ times (step S6, amplification step). Further, the second digital conversion processing unit 70 converts the amplified large amplitude component analog signal (second enlarged signal) 41a shown in FIGS. 8D and 9A into the second digital signal 70a. Convert (second digital conversion processing step).

On the other hand, the enlargement unit 32 enlarges the first digital signal output in the first digital conversion processing step S3 by n ₂ times in parallel with the steps S4 to S7 (step S8, enlargement step). Further, the first enlarged signal 32a enlarged in the enlargement step S8 and the second digital signal 70a of the second digital conversion processing step S7 are added (step S9, digital addition step).

  Reference numeral 81 in FIG. 9B is a component of the first digital signal. A thick line portion denoted by reference numeral 81 is a component 70a obtained by enlarging and quantizing the small-amplitude subtraction signal 41a. As shown in FIG. 9B, the reproducibility of the waveform is enhanced by the addition of the large amplitude component 32a and the small amplitude component 70a. That is, a high-resolution digital signal 80a shown in FIG. 9C can be obtained. In the examples shown in FIGS. 8 and 9, the sampling rates of the first and second digital signals and the number of quantization bits are the same.

Referring to FIG. 4 again, in the configuration of the first embodiment, the enlargement unit 32 and the addition processing unit 80 are represented as individual elements. The enlargement unit 32 and the addition processing unit 80 can also be realized by a CPU, a memory, and a program.
In this case, the physical quantity change measuring device (displacement measuring device) processes the data stored in the memory that is provided in the memory and the memory that stores the output signals of the first and second digital conversion processing units 30 and 70. CPU. Then, the physical quantity change measurement (displacement measurement) program uses the CPU and the memory to cause the CPU to execute necessary settings, enlargement processing, and addition.

The displacement measurement program includes a first setting procedure (setting 1) for setting the gain n _{1 of the} amplifying unit and a second setting procedure (setting) for setting the expansion coefficient n ₂ of the expanding unit. 2), an enlargement procedure (corresponding to step S8) for enlarging the first digital signal output from the first digital conversion processing unit by n ₂ times, and an enlargement procedure corresponding to the enlargement procedure A digital addition procedure (corresponding to step S9) for adding one enlarged signal 30a and the second digital signal 70a of the second digital conversion processing unit 70 is executed.

In this example, the program can set n ₁ used in step S6 in FIG. 7 and n ₂ used in step S8. Therefore, n ₁ and n ₂ can be set from an input device such as a keyboard or a panel connected to the CPU. Further, when the displacement measuring apparatus has a measurement mode (role or intention of measurement), the values of n ₁ and n ₂ may be automatically set when the measurement mode is selected.

  The displacement measurement program may be stored in a recording medium such as an optical disk and copied to an auxiliary storage device provided in the CPU of the displacement measurement device. When the displacement measuring device is connected to a network during steady state or maintenance, the program (file) is transmitted to the displacement measuring device via a network from a recording medium such as a hard disk provided in a remote server. You may make it do.

(Example 3)
In FIG. 10, the structural example of Example 3 of this invention is shown. The third embodiment is obtained by adding configurations necessary for the synchronization processing indicated by reference numerals 90, 91, and 92 to the configurations of the first and second embodiments. That is, the displacement measuring apparatus according to the third embodiment includes a synchronization processing unit 90 that synchronizes the two branched signals based on the cycle of the drive signal (excitation signal) 10 a that drives the displacement sensor 10.

In the methods of the first and second embodiments, the signal 11a directly sent from the smoothing unit 11 to the subtraction processing unit 40 and the first digital conversion processing unit 30 and the analog conversion processing unit 31 are sent to the subtraction processing unit 40. Depending on the operation speed of the A / D converter and the frequency of the displacement signal, there may be a phase difference due to a difference in processing process. This phase difference becomes an error factor when performing highly accurate measurement. Here, the synchronization processing unit 90 performs synchronization processing 91 and 92 on the two signals 11a and 31a input to the subtraction processing unit 40 to solve the problem of the phase difference that may occur between the two signals. As an input signal for realizing the synchronization processing, the excitation signal 10a of the displacement sensor 10 can be used.
According to the third embodiment, high-precision measurement can be realized by avoiding the occurrence of a phase difference between two signals in two-line signal processing.

  Further, according to the third embodiment, dispersion (variation) of delay is allowed for the processing of the first digital conversion unit 30 and the analog conversion unit 31. That is, even if there is a variation in which a delay is small at one time and a large delay at another time, variation in delay is allowed for a period that can be delayed by the synchronization processing 92. Then, more advanced signal processing can be performed on the processing contents corresponding to the digital conversion processing 30 and the analog processing unit 313 shown in FIG.

FIG. 11 shows an example of noise 93 generated when extracting a large amplitude component. In the processing of the first digital conversion processing unit 30 and the analog conversion processing unit 31, noise 93 as shown in FIG. 11 may occur at the moment when the voltage changes. If this noise 93 is left as it is, it will be similarly magnified by the amplifying unit 41 or the enlarging unit 32, which may cause a large error. Therefore, for example, this influence can be avoided by setting the quantization sampling timing of the first digital conversion processing unit 30 to the arrow position shown in FIG.
Further, immediately before the synchronization processing 91, a high frequency component may be removed by a low pass filter.

Example 4
In the examples shown in the first to third embodiments, a component having a large amplitude exceeding a threshold value is extracted from the output of one displacement sensor 10, and a component having a small amplitude is calculated by calculating a difference from its own signal. Asked. In the fourth embodiment, by using two or more sets of displacement sensors, the same signal processing as in the first to third embodiments is realized without branching by the input unit 20.

  FIG. 12 shows a configuration example of the fourth embodiment of the present invention. The difference from the configuration of FIG. 4 is that the input unit 20 is not provided and the second displacement sensor 100 and the smoothing unit 110 are provided. In this example, the signal of the second displacement sensor 100 is used as the displacement signal 110 a input to the first digital conversion processing unit 30. Even if any sensor is used for the second displacement sensor 100, the same effects as in the first to third embodiments can be realized. Even if the linearity of the displacement-voltage conversion characteristic of the first displacement sensor 10 is not good, a highly accurate measurement can be performed by using the highly accurate displacement sensor 100 and using the output displacement as a reference value. Become.

In the example shown in FIG. 13, the second displacement sensor 100 is installed at a position 101 where a displacement amount that is 1 / m of the displacement amount measured by the first displacement sensor 10 is measured.
When the dynamic range of the second displacement sensor 100 is smaller than the range of the first displacement sensor 10, the displacement measurement position 101 of the second displacement sensor 100 can be moved to a position close to the fulcrum. When the measurement position 101 of the second displacement sensor 100 is set to the center position (m = 2) between the displacement sensor 10 and the fulcrum, the dynamic range of the second displacement sensor may be 1/2 that of the first sensor. .
In any of the methods shown in the fourth embodiment, the signal processing unit in the subsequent stage can realize the displacement enlargement detection method using the same method as in the first embodiment.

  As described above, by using two or more sets of displacement sensors, high accuracy can be maintained by using another high-accuracy sensor even if a sensor having large non-linearity of displacement sensitivity is used. When a highly accurate sensor is used, even if the measurable range is narrow, it is possible to deal with the entire range of the displacement sensor by setting the detection position to a position closer to the viewpoint of the probe.

As described above, according to the physical quantity change measuring device and the displacement measuring device having such a configuration, the following remarkable effects can be obtained.
(1) Obtaining a large amplitude component and a small amplitude component from the voltage signal of the sensor, amplifying and quantizing the small amplitude component, expanding the large amplitude component, the amplified small amplitude component, and the expanded large amplitude component In the first to fourth embodiments that add the above, it is possible to realize high-resolution signal processing and measurement by enlarging the physical quantity such as displacement without lowering the measurement range. Conventionally, in order to realize high-resolution and high-bandwidth measurement, it has been necessary to perform precise alignment of the object to be measured. However, the work load is greatly reduced by the method disclosed in each example. .

(2) In the third embodiment in which synchronization processing is performed, highly accurate measurement can be realized by avoiding the occurrence of a phase difference between two signals in two-line signal processing.

(3) In Example 4 using two or more sets of sensors, high accuracy can be maintained by using another high-accuracy sensor even if a sensor having a large nonlinearity of displacement sensitivity is used. . When a highly accurate sensor is used, even if the measurable range is narrow, it is possible to deal with all the ranges of the displacement sensor by setting the detection position to a position close to the fulcrum of the measuring element.

  Note that the physical quantity change measuring device of the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the gist of the present invention. For example, the first digital signal processing unit and the analog conversion processing unit may be integrated as an extraction unit. The extraction unit may extract a large amplitude component using a comparator that compares the voltage signal with a predetermined value, a differentiator that differentiates the output signal, and the like.

As described above, according to the physical quantity change measurement device of the present invention, it is possible to achieve an excellent effect that high-resolution measurement can be performed without narrowing the measurement range. Further, by adjusting the values of the gain n ₁ and the expansion coefficient n ₂ according to the measurement application, it is possible to obtain a measurement value in which the small amplitude component is emphasized and a measurement value in which the large amplitude component is emphasized.

  In the present invention, physical quantities such as displacement, velocity, acceleration, sound, light (image), electromagnetics, and temperature can be used for highly accurate measurement. Moreover, about displacement measurement, it can utilize for the highly accurate measurement etc., such as a shape and surface roughness, for example.

FIG. 1 is a diagram illustrating a configuration example in the embodiment. FIG. 2 is a diagram illustrating the relationship between the measurement range and the voltage detection range. FIG. 3 is a diagram illustrating an operation principle according to the embodiment. FIG. 4 is a diagram illustrating an example of an output signal. FIGS. 5A to 5B are diagrams showing a differential transformer which is an example of a displacement sensor. FIGS. 6A to 6F are diagrams for explaining the outline of signal processing in the first embodiment. FIG. 7 is a diagram for explaining the order of signal processing in the second embodiment. FIGS. 8A to 8D are diagrams for explaining the details of the signal processing in the first embodiment. FIGS. 9A to 9C are diagrams for explaining the details of the signal processing in the first embodiment. FIG. 10 is a diagram illustrating a configuration example according to the third embodiment. FIG. 11 is a diagram illustrating an example of overshoot. FIG. 12 is a diagram illustrating a configuration example according to the fourth embodiment. FIG. 13 is a diagram illustrating an example of an arrangement position of the second sensor in the fourth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Sensor (displacement sensor), 11 ... Smoothing part, 20 ... Input part (branch part), 30 ... 1st digital conversion process part, 31 ... Analog conversion process part, 32 ... Enlargement part (1st enlargement process) Part), 40 ... subtraction processing part, 41 ... amplification part (second enlargement processing part), 70 ... second digital conversion processing part, 80 ... addition processing part, 90 ... synchronization processing part, 100 ... second displacement Sensor.
11a, 11b ... voltage signal from sensor, 30a ... first digital signal (large amplitude component, digital), 31a ... first analog signal (large amplitude component, analog), 40a ... subtraction signal (small amplitude component, analog) ), 41a, second enlarged signal (small amplitude component, analog), 70a, second digital signal (small amplitude component, digital), 80a, output signal (addition of small amplitude component and large amplitude component, digital).

Claims (8)

An input unit that inputs an analog voltage signal corresponding to a change in physical quantity detected by the sensor and divides the voltage signal into two systems;
A first digital conversion processing unit for converting one of the two voltage signals into a digital signal and outputting a first digital signal;
An analog conversion processing unit for converting the first digital signal into an analog signal and outputting the first analog signal;
A subtraction processing unit that outputs a subtraction signal obtained by subtracting the first analog signal from the other voltage signal divided into the two systems;
A first enlargement processing unit for enlarging the first digital signal and outputting a first enlarged signal;
A second enlargement processing unit that enlarges the subtraction signal and outputs a second enlargement signal;
A second digital conversion processing unit for converting the second enlarged signal into a digital signal and outputting a second digital signal;
An apparatus for measuring change in physical quantity, comprising: an addition processing unit that outputs an output signal obtained by adding the second digital signal and the first enlarged signal. Claim 1, characterized in that setting the magnification factor n ₂ of the second enlargement processing unit and the magnification factor n ₁ of the first enlargement processing section based on the resolution of the first digital conversion processing unit The physical quantity change measuring device described. The physical quantity change measuring apparatus according to claim 1, further comprising a synchronization processing unit that synchronizes the two branched signals based on a cycle of a drive signal that drives the sensor. A sensor process for measuring the amount of change in the physical quantity of the object to be measured and outputting an analog voltage signal corresponding to the amount of change;
An input process for dividing the voltage signal into two systems;
A first digital conversion processing step of converting one of the two voltage signals into a digital signal and outputting a first digital signal;
A first analog conversion processing step of converting the first digital signal into an analog signal and outputting the first analog signal;
A first analog subtraction step for outputting a subtraction signal obtained by subtracting the first analog signal from the other voltage signal divided into the two systems;
A first enlargement processing step of enlarging the first digital signal and outputting a first enlarged signal;
A second enlargement processing step of enlarging the subtraction signal and outputting a second enlargement signal;
A second digital conversion processing step of converting the second enlarged signal into a digital signal and outputting a second digital signal;
An addition processing step of outputting an output signal obtained by adding the second digital signal and the first enlarged signal. A physical quantity change measuring method comprising: An analog voltage signal corresponding to a change in the physical quantity detected by the sensor is input, and an input unit that divides the voltage signal into two systems, and one voltage signal divided into the two systems is converted into a digital signal. A first digital conversion processing unit that outputs a first digital signal, an analog conversion processing unit that converts the first digital signal into an analog signal and outputs a first analog signal, and the two systems are divided. A subtraction processing unit that outputs a subtraction signal obtained by subtracting the first analog signal from the other voltage signal; an amplification unit that amplifies the amplitude of the subtraction signal by n ₁ times and outputs a second enlarged signal; A second digital conversion processing unit that converts the second enlarged signal into a digital signal and outputs the second digital signal; a memory that stores the first and second digital signals as data; A physical quantity change measurement program for measuring a change in a physical quantity using a physical quantity change measuring device provided with a CPU functioning as a predetermined enlargement unit by processing data stored in the memory. Because
In the CPU
A first setting procedure for setting the gain n _{1 of the} amplifying unit;
A second setting procedure for setting the enlargement factor n ₂ of the enlargement part;
An enlargement procedure for enlarging the first digital signal output from the first digital conversion processor by n ₂ times and outputting a first enlarged signal;
A physical quantity change measurement program for executing an addition procedure for outputting an output signal obtained by adding the first enlarged signal and the second digital signal enlarged according to the enlargement procedure. A recording medium on which the physical quantity change measurement program according to claim 5 is recorded. A first displacement sensor that detects a change in the physical quantity of the object to be measured and outputs a voltage signal corresponding to the change in the physical quantity;
A second displacement sensor that detects a change in the physical quantity of the object to be measured and outputs a voltage signal having an amplitude corresponding to the change in the physical quantity;
A first digital conversion processing unit that converts a voltage signal of the second displacement sensor into a digital signal and outputs a first digital signal;
An analog conversion processing unit for converting the first digital signal into an analog signal and outputting the first analog signal;
A first enlargement processing unit for enlarging the first digital signal and outputting a first enlarged signal;
A subtraction processing unit for subtracting the first analog signal from the voltage signal of the first displacement sensor and outputting a subtraction signal;
A second enlargement processing unit for enlarging the subtraction signal and outputting a second enlarged signal;
A second digital conversion processing unit for converting the second enlarged signal into a digital signal and performing a second digital signal;
A physical quantity change measuring device comprising: an addition processing unit that outputs an output signal obtained by adding the second digital signal and the first enlarged signal. 8. The physical quantity change measuring device according to claim 7, wherein the second sensor is installed at a position for measuring a displacement amount that is 1 / m of a displacement amount measured by the first sensor.

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