JP5172356B2 - Measuring apparatus, measuring method and program - Google Patents

Description

  The present invention relates to a measurement apparatus, a measurement method, and a program configured to be able to measure a physical quantity such as a voltage of a measurement object.

  As this type of measuring apparatus, a voltage measuring apparatus disclosed in JP-A-6-242166 is known.

This voltage measuring device (distance compensation surface potential meter) includes a sensor unit using a piezoelectric tuning fork and a detection electrode, a tuning fork drive circuit, a preamplifier circuit connected to the detection electrode of the sensor unit, an amplifier circuit, and synchronous detection. The circuit includes an integration circuit and a high-voltage amplifier circuit. In this voltage measuring device, the sensor unit, the preamplifier circuit, the amplifier circuit, the synchronous detection circuit, the integration circuit, the primary side of the high-voltage amplifier circuit, the secondary side of the power supply circuit using the transformer, and its shield are floated from the power source, and The generated voltage of the high-voltage amplifier circuit is fed back to at least the common ground of the sensor unit, and feedback control is performed so that the generated voltage becomes equal to the voltage of the measurement object. According to this voltage measurement device, the voltage of the measurement object can be measured by detecting the voltage generated by the high-voltage amplifier circuit.
Japanese Laid-Open Patent Publication No. 6-242166 (pages 13-15, Fig. 2)

  By the way, the feedback control used in this type of measuring device has a characteristic that a deviation occurs. Further, for example, in the case of proportional control, this deviation varies depending on the gain of the feedback loop, and the gain is large. Sometimes it becomes small, and when the gain is small, it becomes large. For this reason, in this type of measurement apparatus, normally, an allowable deviation is determined in consideration of measurement accuracy and the like, and the gain of the feedback loop is set so as to be a gain corresponding to the determined deviation.

  However, in the apparatus configured to measure the voltage of the measurement object in a non-contact manner, such as the voltage measurement apparatus described above, even if the distance to the measurement object is constant, the measurement object is affected by changes in humidity or the like. As a result, the gain of the sensor unit changes and the gain of the feedback loop also changes to a value different from the value assumed in advance. Also, with this voltage measuring device, there is no way to confirm the actual feedback loop gain. For this reason, a measuring device such as this voltage measuring device measures the voltage as usual even when the actual feedback loop gain at the time of measurement becomes smaller than a gain that can ensure an acceptable deviation. Therefore, there is a problem that the reliability of measurement cannot be ensured. On the other hand, even if the gain of the feedback loop changes due to changes in humidity or the like, a method of setting the gain of the feedback loop to a sufficiently large value from the beginning is also conceivable so that a sufficient gain can be secured. However, when the gain of the feedback loop is increased too much, the noise resistance characteristic of the feedback loop is degraded, and there is still a problem that a situation where the reliability of measurement cannot be ensured occurs.

  The present invention has been made to solve the above problems, and has as its main object to provide a measuring apparatus, a measuring method, and a program that can ensure the reliability of measurement.

In order to achieve the above object, the measuring apparatus according to claim 1 generates a reference physical quantity corresponding to a physical quantity of a measurement object by feedback control so that a difference from the physical quantity is reduced, and based on the reference physical quantity, a measuring device for calculating the physical quantity of the measured object, the change the gain of the feedback control to measure the reference physical quantity before and after of the changes, the difference between the two reference physical quantity the measurement the two In a state where the gain of the feedback control in which the calculated value obtained by dividing one of the reference physical quantities is less than a predetermined reference value is good, the calculated value and the gain after the change with respect to the gain before the change The physical quantity of the measurement object is calculated based on the gain magnification and the reference physical quantity at the time of high gain among the two reference physical quantities.

The measurement apparatus according to claim 2 generates a reference physical quantity corresponding to the physical quantity of the measurement target object by feedback control so that a difference from the physical quantity decreases, and based on the reference physical quantity, a measuring device for calculating the physical quantity, wherein the gain of the feedback control is changed to 2-fold to measure the reference physical quantity before and after of the change, in the high gain of the two reference physical quantity the measurement The calculated value obtained by dividing the reference physical quantity by the reference physical quantity at the time of low gain is less than a predetermined reference value. When the gain of the feedback control is good, the calculated value and the reference physical quantity at the time of high gain are Based on this, the physical quantity of the measurement object is calculated.

A measuring apparatus according to a third aspect is the measuring apparatus according to the first or second aspect , wherein the calculated physical quantity is output to an output unit.

According to a fourth aspect of the present invention, the reference physical quantity corresponding to the physical quantity of the measurement object is generated by feedback control so that the difference from the physical quantity is reduced, and the measurement object is measured based on the reference physical quantity. a measuring method for calculating the physical quantity, by changing the gain of the feedback control to measure the reference physical quantity before and after of the change, among the two reference physical quantity the difference between two reference physical quantity the measurement The calculated value calculated by the division is less than a predetermined reference value. When the gain of the feedback control is good, the calculated value and the gain before the change are Based on the gain scale factor after the change and the reference physical quantity at the time of high gain of the two reference physical quantities, the physical quantity of the measurement object is calculated. Out to.

According to a fifth aspect of the present invention, the reference physical quantity corresponding to the physical quantity of the measurement object is generated by feedback control so that the difference from the physical quantity is reduced, and the measurement object is measured based on the reference physical quantity. a measuring method for calculating the physical quantity, wherein the gain of the feedback control is changed to 2-fold to measure the reference physical quantity before and after of the change, in the high gain of the two reference physical quantity the measurement The reference physical quantity is divided by the reference physical quantity at the time of low gain, and the calculated value calculated by the division becomes less than a predetermined reference value. Based on the reference physical quantity at the time of gain, the physical quantity of the measurement object is calculated.

In addition, the program according to claim 6 generates a reference physical quantity corresponding to the physical quantity of the measurement object, and detects a difference between the physical quantity of the measurement object and the reference physical quantity. a feedback control section for feedback controlling the reference physical quantity as decreasing, the procedure for changing the gain of the feedback loop to the feedback control unit in the measurement apparatus and a measurement unit for measuring the reference physical quantity, wherein A procedure for obtaining the reference physical quantity before and after the change of the gain measured by the measurement unit, and a calculated value obtained by dividing the difference between the two obtained reference physical quantities by one of the two reference physical quantities a step of calculating, said gain of the feedback control in which the calculated value is less than a predetermined reference value In good conditions, and the calculated value, and the magnification of the gain after the change to the gain before the change, on the basis of the reference physical quantity at the time of high gain of the two reference physical quantity, wherein the measured object And a procedure for calculating a physical quantity.

Further, the program according to claim 7 generates a reference physical quantity corresponding to the physical quantity of the measurement object, and detects a difference between the physical quantity of the measurement object and the reference physical quantity. a feedback control section for feedback controlling the reference physical quantity as decrease, the procedure for changing the gain of the feedback loop is doubled with respect to the feedback control unit in the measurement apparatus and a measurement unit for measuring the reference physical quantity A procedure for acquiring the reference physical quantity before and after the change of the gain measured by the measurement unit, and a reference physical quantity at a high gain of the two acquired reference physical quantities is a reference physical quantity at a low gain. a step of calculating a calculated value by dividing, before the feedback control of the calculated value is less than a predetermined reference value Gain in good condition, and the calculated value, based on the reference physical quantity at the time of the high gain, to perform the procedure for calculating the physical quantity of the measured object.

Measuring device 請 Motomeko 1 wherein, according to claim 4 measuring method and claim 6, wherein the program description, reference before and after the change over the gain of the feedback loop in the feedback control is changed the gain in good condition The physical quantity is measured, the difference between the two measured reference physical quantities is divided by one of the two reference physical quantities, the calculated value calculated by the division, and the gain multiplication factor after the change with respect to the gain before the change, By increasing the physical quantity of the measurement object based on the reference physical quantity at the time of high gain of the two reference physical quantities, the reliability (measurement accuracy) of measuring the physical quantity of the measurement object by the measurement device is increased. Can do.

Further, according to the measurement apparatus according to claim 2, the measurement method according to claim 5, and the program according to claim 7 , the gain is doubled and changed when the gain of the feedback loop in the feedback control is good. The reference physical quantity is measured before and after the reference physical quantity at the time of high gain of the two measured reference physical quantities is divided by the reference physical quantity at the time of low gain, and the calculated value calculated by the division and the reference at the time of high gain By calculating the physical quantity of the measurement object based on the physical quantity, the reliability (measurement accuracy) of the measurement apparatus for measuring the physical quantity of the measurement object can be increased.

In addition, according to the measurement device of claim 3 , by outputting the calculated physical quantity of the measurement object to an output unit such as a display device, the physical quantity of the measurement object can be confirmed in the output unit, and measurement can be performed. The trouble of connecting another output device to the device can be saved.

Hereinafter, with reference to the accompanying drawings, measurement devices, the best mode of the measuring method, and a program will be described by way of example applied to the voltage measuring device.

  First, the voltage measuring apparatus 1 will be described with reference to the drawings.

  As shown in FIG. 1, the voltage measuring device 1 includes a probe unit 2 and a main unit 3, and is configured to be able to measure the voltage V <b> 1 (an example of a physical quantity in the present invention) of the measurement object 4 without contact.

  As shown in FIG. 1, the probe unit 2 includes a case 11, a detection electrode 12, a variable capacitance circuit 19, a current detector 15, and a preamplifier 16, and functions as a sensor unit in the present invention. The case 11 is configured using a conductive material (for example, a metal material). For example, the detection electrode 12 is formed in a flat plate shape, and is fixed to the case 11 so that one surface side thereof is exposed on the outer surface of the case 11 and the other surface side is exposed inside the case 11. Yes. As an example, the detection electrode 12 is attached to a hole (not shown) provided in the case 11 in a state of closing the hole and being electrically insulated from the case 11. In this example, as an example, the case 11 has a surface covered with an insulating film formed of a resin material or the like. In this case, the detection electrode 12 may be covered with this insulating film, or may be exposed from the insulating film.

  As illustrated in FIG. 1, the variable capacitance circuit 19 includes one capacitance change function body 13 and one drive circuit 14. The variable capacitance circuit 19 (specifically, the capacitance changing function body 13) includes a first structural unit 31, a second structural unit 32, a third structural unit 33, and a fourth structural unit 34 in this order. They are connected in a (bridge shape) to form a so-called bridge circuit. Specifically, as shown in FIG. 2, each of the structural units 31, 32, 33, and 34 includes first electric elements E11, E12, E13, and E14 (hereinafter referred to as “first electric element E1 unless otherwise specified). Are also included one by one.

  In this case, each first electrical element E1 functions as a resistor when one end has a high potential with respect to the other end, and functions as a capacitor when the other end has a high potential with respect to the other end. Each of the first elements 41a and 41b (hereinafter also referred to as the first element 41 unless otherwise distinguished), and the first elements 41 are connected in series in opposite directions. Thereby, each 1st electric element E1 is comprised so that a capacity | capacitance may change according to the magnitude | size of the absolute value of an applied voltage, preventing passage of a DC signal. In this example, as an example, each first element 41 includes a P-type semiconductor and an N-type semiconductor that are joined to each other. Specifically, one first diode (for example, a variable-capacitance diode; a varicap or a varactor). Each first electric element E1 is configured by connecting these two diodes in series in opposite directions (with anode terminals connected to each other). In addition, variable capacitance diodes having the same or substantially the same characteristics are used for the first elements 41a and 41b, and the product of the impedances of the first structural unit 31 and the third structural unit 33 and the second configuration. The product of each impedance of the unit 32 and the fourth structural unit 34 is set to be the same or substantially the same (a state that is different within a range of several percent as an example).

  In the capacitance change function body 13 shown in FIG. 2, each first electrical element E1 connects one ends of the pair of first elements 41a and 41b (connects the anode terminals of the pair of diodes). Although it is configured, like the capacitance changing function body 13 shown in FIG. 3, the other ends of the pair of first elements 41a and 41b are connected (the cathode terminals of the pair of diodes are connected), The first electrical element E1 can also be configured. The variable capacitance diode uses a change in capacitance (junction capacitance) due to a change in the thickness of the depletion layer at the PN junction of the diode when a voltage is applied in the reverse direction. This is the one with a large change. On the other hand, even in a general diode (silicon diode) configured with a PN junction, the above-described change in capacitance (junction capacitance) occurs although it is less than a variable capacitance diode. For this reason, all the first elements 41a and 41b in each capacitance change function body 13 shown in FIGS. 2 and 3 are first elements 51a and 51b formed of general diodes (hereinafter referred to as first elements when not distinguished from each other). 51 (also referred to as 51) (see FIGS. 4 and 5), the capacity changing function body 13 can be configured. Although not shown, the MOS-FET maintained in the off state by connecting the gate terminal to the source terminal also functions as a variable capacitor whose capacitance changes based on the voltage applied between the drain and the source. It is known. Therefore, the capacitance changing function body 13 can be configured by using one MOS-FET having the gate terminal connected to the source terminal in this way instead of the variable capacitance diode.

  In addition, as shown in FIG. 1, the variable capacitance circuit 19 includes a first structural unit 31 and a capacitance changing function body 13 between the detection electrode 12 and a portion (case 11 in this example) that becomes the reference potential Vr. The connection point A of the fourth structural unit 34 is connected to the detection electrode 12 side, and the connection point C of the second structural unit 32 and the third structural unit 33 is connected to the case 11 side. ing. Specifically, in the variable capacitance circuit 19, the connection point A of the capacitance change function body 13 is directly connected to the detection electrode 12, and the connection point C of the capacitance change function body 13 is connected to the case 11 via the current detector 15. Is connected between the detection electrode 12 and the case 11. A connection point B between the first structural unit 31 and the second structural unit 32 and a connection point D between the third structural unit 33 and the fourth structural unit 34 are connected to the drive circuit 14. The variable capacitance circuit 19 is disposed inside the case 11 without being exposed to the outside of the case 11.

  The drive circuit 14 is configured using, for example, insulating electronic components such as a transformer and a photocoupler, and the drive signal S1 input from the main unit 3 is electrically insulated from the drive signal S1 and the drive signal S1. To the drive signal S2 having the same frequency f1 and output (applied) to the capacitance changing function body 13. In this example, as an example, the drive circuit 14 is configured using an insulating transformer Tr1 having a primary winding Tr1a and a secondary winding Tr1b as shown in FIG. In this case, each end of the secondary winding Tr1b is connected to the connection points B and D of the capacitance changing function body 13. In the drive circuit 14, the primary winding Tr1a is excited based on the input drive signal S1, so that the transformer Tr1 generates the drive signal S2 in the secondary winding Tr1b. With this configuration, the drive circuit 14 converts the drive signal S1 into the drive signal S2 with low distortion, and applies the drive signal S2 between the connection points B and D of the capacitance change function body 13. In this example, since a sine wave signal is used as the drive signal S1 as an example as described later, the drive signal S2 is also output as a sine wave signal. Further, instead of the drive circuit 14 described above, a floating signal source (not shown) that outputs the drive signal S2 alone without inputting the drive signal S1 from the main unit 3 may be disposed in the probe unit 2. it can.

  The current detector 15 is constituted by an insulating transformer Tr2 as an example and functions as a detection circuit in the present invention. The current detector 15 has one end of the primary winding Tr2a of the transformer Tr2 connected to the variable capacitance circuit 19 (specifically, the connection point C of the capacitance changing function body 13 in the variable capacitance circuit 19) and the other end. Are connected to the case 11 and connected between the variable capacitance circuit 19 and the case 11. As a result, the current detector 15 (that is, the transformer Tr2) is disposed between the detection electrode 12 and the case 11 while being connected in series with the variable capacitance circuit 19, and the capacitance changing function body of the variable capacitance circuit 19 is provided. 13 is detected, and a voltage V2 having an amplitude proportional to the current value (amplitude) of the current i is induced (generated) in the secondary winding Tr2b. The preamplifier 16 amplifies the voltage V2 induced in the secondary winding Tr2b of the transformer Tr2 and outputs it as a detection signal S3. In this case, since the voltage V2 changes in proportion to the value of the current i, the detection signal S3 generated by amplifying the voltage V2 also changes in proportion to the value of the current i. Further, the current detector 15 and the preamplifier 16 described above are disposed inside the case 11 together with the variable capacitance circuit 19.

  As shown in FIG. 1, the main unit 3 includes a control unit 3a, a voltage generation unit 3b, a processing unit 3c, a voltmeter 3d, and an output unit 3e. In this case, the control unit 3a constitutes the feedback control unit FC according to the present invention together with the probe unit 2 as the sensor unit and the voltage generation unit 3b, and an analog signal S5 and a polarity signal to be described later based on the input detection signal S3. S8 is generated and output to the voltage generator 3b, and the voltage of the reference potential Vr is changed with respect to the voltage generator 3b. Specifically, the control unit 3a includes an oscillation circuit 21, a filter circuit 22, an amplification circuit 23, a detection circuit 24, and a polarity determination circuit 25. The oscillation circuit 21 generates a drive signal S1 having a constant period T1 (frequency f1) and outputs it to the probe unit 2. The oscillation circuit 21 generates a detection signal S11 having a period T2 (frequency f2 = 2 × f1) that is a half of the period T1 in synchronization with the drive signal S1 and outputs the detection signal S11 to the polarity determination circuit 25. In this case, in this example, the oscillation circuit 21 generates a sine wave signal as the drive signal S1 and the detection signal S11. The filter circuit 22 selectively allows a signal S3a having the same frequency as the capacitance modulation frequency f2 of the capacitance change function body 13 included in the detection signal S3 input from the probe unit 2 to pass therethrough.

  The amplifier circuit 23 amplifies the signal S3a input from the filter circuit 22 and outputs it as a detection signal S4. Further, immediately after the operation starts, the amplifier circuit 23 amplifies the signal S3a with a preset initial gain (initial gain Ga0), and when the control signal S12 is input from the processing unit 3c, the gain is multiplied by α. Change to Ga1 (= α × Ga0). As a result, the gain of a feedback loop, which will be described later, of the voltage measuring apparatus 1 also becomes α times. In this example, since the capacitance modulation frequency f2 of the capacitance change function body 13 is twice the frequency f1 of the drive signal S2, the frequency of the current i generated by the change in the capacitance C1 of the capacitance change function body 13 is also set. The detection signal S3 generated by the preamplifier 16 includes twice the frequency f1 of the drive signal S1, and each of the signal components of the frequencies f1 and f2 is included in the detection signal S3. Filtered by the circuit 22 results in f2. The detection circuit 24 generates the analog signal S5 by detecting the detection signal S4 using, for example, an envelope detection method. In this case, the amplitude (voltage value) of the analog signal S5 changes in proportion to the current value of the current i flowing through the variable capacitance circuit 19. Therefore, since the detection signal S3 is also a signal that changes in proportion to the amplitude (current value) of the current i, the analog signal S5 and the detection signal S3 are synchronized with each other and become proportional signals. The polarity determination circuit 25 receives the detection signal S11 and the detection signal S4 and detects the phase of the detection signal S4 with respect to the detection signal S11. The polarity determination circuit 25 determines the polarity of the potential difference (V1−Vr) between the voltages V1 and Vr of the measurement object 4 and the case 11 based on the detected phase, and outputs a polarity signal S8 indicating this polarity. Generate and output. As an example, in this example, the polarity determination circuit 25 outputs the polarity signal S8 with the same polarity as the polarity of the potential difference (V1-Vr).

  As an example, the processing unit 3c includes a computer having a CPU and an internal memory. In this case, in the processing unit 3c, the CPU changes the gain of the feedback loop in the feedback control executed by the feedback control unit FC according to the program stored in the internal memory (in this example, the gain before the change is changed to α (> 1) Gain change processing (changed by multiplying) (procedure for changing gain), and voltages (reference potential Vr.) Of two reference potential signals S7 measured by the voltmeter 3d before and after the gain change. Voltage acquisition process (procedure for acquiring the reference physical quantity) to acquire the reference physical quantity), and the difference ΔVr between the two acquired reference potentials Vr is divided by one of the reference potentials Vr to change the reference potential Vr change rate H ( = ΔVr / Vr (calculated value in the present invention) and a change rate calculation process (a procedure for calculating the calculated value) and feedback based on the change rate H Voltage calculation for calculating the voltage V1 of the measurement object 4 based on the pass / fail determination process (procedure for executing the determination process) for determining the pass / fail of the gain, the change rate H, the magnification α, and the two acquired reference potentials Vr. The process (procedure for calculating the physical quantity of the measurement object) and the output process (procedure for executing the output process) for outputting the result of the pass / fail judgment process and the data D1 indicating the calculated voltage V1 to the output unit 3e are executed. . The internal memory stores in advance the above-described program that causes the CPU to execute each of the above-described processes, the magnification α, and the reference value Dr that is used in the pass / fail determination process. Further, the processing unit 3c can be configured by a programmable logic such as an FPGA or a gate array instead of the above configuration.

  The voltage generation unit 3b includes a voltage generation circuit 27 and a transformer (step-up transformer) Tr3. The voltage generation circuit 27 generates and outputs a voltage signal S6. In this case, when the polarity of the input polarity signal S8 is “positive”, the voltage generation circuit 27 outputs the voltage of the output voltage signal S6 by an amount proportional to the amplitude (voltage value) of the input analog signal S5. On the contrary, when it is “negative”, it is decreased. The transformer Tr3 is an insulating transformer, and includes a primary winding Tr3a (turn number: n1) and a secondary winding Tr3b (turn number: n2> n1), and is configured as a step-up transformer. In this case, one end of each of the primary winding Tr3a and the secondary winding Tr3b is grounded (connected to the ground). The other end of the primary winding Tr3a is connected to the voltage generation circuit 27, and the other end of the secondary winding Tr3b is connected to the case 11 of the probe unit 2. With this configuration, the transformer Tr3 boosts the voltage signal S6 input to the primary winding Tr3a, outputs the boosted voltage signal S6 to the other end of the secondary winding Tr3b as a reference potential signal S7, and applies it to the case 11 of the probe unit 2. To do. In this manner, in the case 11, the potential (reference potential) Vr is defined as the voltage of the reference potential signal S7.

  The voltmeter 3d is a measuring unit in the present invention, and repeatedly measures the voltage (reference potential Vr) of the reference potential signal S7, and indicates the measured voltage value (reference potential Vr) of the reference potential signal S7 for each measurement. The data D2 is output to the processing unit 3c. In this example, the output unit 3e is configured by a display device as an example, and based on the data D1 from the processing unit 3c, for example, information indicating whether or not the gain of the current feedback loop is good, and At least one of the calculated voltages V1 is displayed. As an example, the output unit 3e is represented by characters used in a language such as Japanese or English when the gain of the feedback loop is good, “gain is good” (or “measurement value is valid”). Voltage V1 is displayed together with (information), and when it is not good (bad), the voltage V1 is not displayed, and character information “Gain is not good” (or “measurement is invalid”) is displayed. As the output unit 3e, in addition to the display device, a printing device that prints the above information can also be adopted, and the current feedback loop gain is good (or not good). It is possible to employ a notification device that notifies the user of a buzzer sound, sound, and LED display state (colors to be turned on, turned off, blinking or turned on, or a combination thereof) and a transmission device that transmits data indicating that.

  Next, the measurement operation of the voltage measuring apparatus 1 will be described. In order to facilitate understanding of the invention, as an example, the voltage generation circuit 27 generates a zero-volt voltage signal S6 at the start of the measurement operation of the voltage measurement apparatus 1 (time t0), and then increases the voltage. Or decrease. Therefore, it is assumed that the voltage generation unit 3b starts to generate the reference potential signal S7 from zero volts as shown by a solid line in FIG.

  First, when measuring the voltage V1, the probe unit 2 is arranged in the vicinity of the measurement object 4 so that the detection electrode 12 faces the measurement object 4 in a non-contact state. As a result, as shown in FIG. 1, the capacitance C <b> 0 is formed between the detection electrode 12 and the measurement object 4. In this case, the capacitance value of the capacitance C0 varies in inverse proportion to the distance between the detection electrode 12 and the measurement object 4, but after the probe unit 2 is completely disposed, the environmental conditions such as humidity are constant. Originally constant (does not change). However, the capacitance C0 varies when environmental conditions such as humidity change.

  Next, in the activated state of the voltage measuring device 1, in the control unit 3a, the oscillation circuit 21 starts generating the drive signal S1 and the detection signal S11, and the drive signal S1 is supplied to the probe unit 2 and the detection signal S11 is supplied Output to the polarity determination circuit 25. In the probe unit 2, the drive circuit 14 of the variable capacitance circuit 19 converts the input drive signal S <b> 1 into the drive signal S <b> 2 and applies (outputs) between the connection points B and D of the capacitance change function body 13. In the capacity change function body 13, the drive signal S2 applied between the connection points B and D is divided, and the first structural unit 31, the second structural unit 32, the third structural unit 33, and the fourth structural unit 13 are used. Applied to each of the structural units 34.

  In this case, as shown in FIG. 6, the potential at the connection point B becomes high with respect to the period Ta (the connection point D as a reference) in one cycle T1 of the drive signal S2, and the potential difference between them gradually increases. In the period), the reverse voltage in each first electrical element E1 is applied (reversely biased), and each capacitance of each first element 41 functioning as a capacitor gradually decreases. Specifically, the capacitance of each first element 41b that is reverse-biased in each of the first electric elements E11 and E14, and each of the first electric elements E12 and E13 that are reverse-biased. The capacitance of the first element 41a gradually decreases. Further, during the period Tb of one cycle T1 of the drive signal S2 (period in which the potential at the connection point B becomes high with the connection point D as a reference and the potential difference between the two gradually decreases), the drive signal S2 is reverse-biased. Each of the first elements 41, specifically, each of the first electric elements E11 and E14 has a capacitance of each first element 41b, and each of the first electric elements E12 and E13 has a capacitance of each of the first elements 41a gradually. To increase.

  Further, during the period Tc of one cycle T1 of the drive signal S2 (period in which the potential at the connection point B is low with respect to the connection point D and the potential difference between the two gradually increases), the drive signal S2 is reverse-biased. Each first element 41 that functions as a capacitor, specifically, each first element 41a in each first electrical element E11, E14, and each electrostatic element in each first element 41b in each first electrical element E12, E13. Capacity gradually decreases. Further, during the period Td of one cycle T1 of the drive signal S2 (a period in which the potential at the connection point B is low with respect to the connection point D and the potential difference between the two gradually decreases), the drive signal S2 is reverse-biased. Each first element 41a, specifically each first element 41a in each first electric element E11, E14, and each first element 41b in each first electric element E12, E13 is gradually increased in capacitance. To increase. Note that the first elements 41a and 41b to which the forward voltage is applied (forward biased) among the first elements 41a and 41b included in each first electrical element E1 function equivalently as resistors. doing. For this reason, the capacitance of each first electrical element E1 repeats decreasing and increasing twice within one cycle T1 of the drive signal S2.

  Thus, since the capacitance of each first electrical element E1 included in each structural unit 31 to 34 repeats increasing and decreasing twice each in one cycle T1 of the drive signal S2, these The capacitance C1 (capacitance between the connection points A and B) of the capacitance changing function body 13 formed by synthesizing the capacitance is repeatedly increased and decreased twice. In other words, the variable capacitance circuit 19 continuously increases the capacitance C1 in synchronization with the cycle T1 of the input drive signal S2 and at a cycle T2 (frequency f2 = 2 × f1) that is a half of the cycle T1. In the example, an operation that changes periodically is executed. In this case, as described above, the variable capacitance circuit 19 is connected in series between the case 11 and the detection electrode 12 with the current detector 15 interposed therebetween. The capacitance C0 formed between the body 4 and the detection electrode 12 is in a state of being connected in series between the measurement target body 4 and the case 11. For this reason, when the electrostatic capacitance C1 periodically changes at the frequency f2 (capacitance modulation frequency), the electrostatic capacitance C2 between the measurement object 4 and the case 11 (the series combination of the electrostatic capacitances C0 and C1). As shown in FIG. 6, the (capacitance) also changes in synchronization with the cycle T1 of the drive signal S2 and in a cycle T2 (frequency f2) which is a half of the cycle T1.

  In the variable capacitance circuit 19, as described above, variable capacitance diodes (or general diodes) having the same or substantially the same characteristics are used for the first elements 41 of the capacitance change function body 13, and as a result, The products of the impedances of the first structural unit 31 and the third structural unit 33 and the products of the impedances of the second structural unit 32 and the fourth structural unit 34 are set to be the same or substantially the same. Therefore, since the capacitance changing function body 13 which is also a bridge circuit satisfies the equilibrium condition as the bridge circuit, the voltage component of the drive signal S2 (the voltage signal having the same frequency f1 as the drive signal S1) is connected to each connection point A, The electrostatic capacity C1 is changed with the period T2 in a state where there is almost no generation between C. Also included in each set of first electrical elements E11 and E14 included in each of the structural units 31 and 34 connected to the connection point A and included in each of the structural units 32 and 33 connected to the connection point C. Since the two first electric elements E1 included in at least one of the first electric elements E12 and E13 are always functioning as a capacitor, the detection electrode 12 and the case 11 is connected in an AC manner through the variable capacitance circuit 19 but is maintained in a state where it is not short-circuited in a DC manner.

  For this reason, the capacitance C2 between the measurement object 4 and the case 11 periodically changes in the cycle T2 based on the periodic change in the capacitance C1 in the cycle T2, thereby changing the variable capacitance circuit 19. , A current i (period T2) having an amplitude corresponding to the potential difference (V1−Vr) between the voltages V1 and Vr of the measurement object 4 and the case 11 flows. Specifically, the current i has a large amplitude (current value) when the potential difference (V1-Vr) is large, and a small current value when the potential difference (V1-Vr) is small.

  Therefore, as shown in FIG. 7, when the voltage measurement device 1 starts the measurement operation when the voltage V1 of the measurement object 4 is a positive voltage (time t0), the potential difference (V1-Vr) is a positive voltage. Although not shown, the current i flows as an AC signal whose period is T2 and whose amplitude changes in accordance with the potential difference (V1-Vr). The preamplifier 16 amplifies the voltage V2 induced in the secondary winding Tr2b of the transformer Tr2 constituting the current detector 15 due to the current i, and outputs it as a detection signal S3. In this case, the detection signal S3 mainly includes the same frequency component as the frequency f2 of the current i, and also includes the same frequency component as the frequency f1 of the drive signal S2.

  In the control unit 3a of the main unit 3, the filter circuit 22 selectively outputs the signal component of the frequency f2 included in the detection signal S3 as the signal S3a, and the amplifier circuit 23 outputs the signal S3a to the initial gain Ga0. To generate a detection signal S4 and output it to the detection circuit 24. Next, the detection circuit 24 detects the input detection signal S4, generates an analog signal S5, and outputs the analog signal S5 to the voltage generation unit 3b. In this case, the analog signal S5 is a signal whose amplitude changes in proportion to the value of the potential difference (V1-Vr). In addition, the polarity determination circuit 25 receives the detection signal S11 and the detection signal S4 and detects the phase of the detection signal S4 with respect to the detection signal S11, so that the polarity becomes the same as the polarity of the potential difference (V1-Vr). A signal S8 is generated and output to the voltage generator 3b.

  In the voltage generation unit 3b of the main unit 3, the voltage generation circuit 27 outputs the voltage of the output voltage signal S6 by an amount proportional to the amplitude (voltage value) of the input analog signal S5. When the polarity is “positive”, it is increased, and conversely when it is “negative”, it is decreased. Therefore, as shown in FIG. 7, when the voltage V1 of the measurement object 4 is a positive voltage (time t0) and the voltage measurement device 1 starts the measurement operation, the voltage signal S6 is initially zero volts. The reference potential signal S7 is also zero volts. As a result, the potential difference (V1−Vr) becomes a positive voltage, and thus the polarity of the polarity signal S8 also becomes positive. Therefore, in the voltage generation unit 3b, the voltage generation circuit 27 increases the voltage value by an amount proportional to the amplitude of the input analog signal S5 and outputs the voltage signal S6. Next, the transformer Tr3 boosts the voltage signal S6, outputs a reference potential signal S7, and applies it to the case 11. As a result, a feedback loop composed of the current detector 15, the preamplifier 16, the filter circuit 22, the amplifier circuit 23, the detection circuit 24, and the voltage generation unit 3b (the voltage generation circuit 27 and the transformer Tr3) (the sensor unit and the voltage in the present invention). In an example of a feedback loop including a generation unit, negative feedback is performed so that the potential difference (V1−Vr :) between the measurement object 4 and the case 11 gradually decreases (decreases).

  Therefore, the current value (amplitude) of the current i gradually decreases (decreases). Generally, in the voltage measuring device 1, the transient characteristic is set so that the convergence of the reference potential Vr to the voltage V1 of the measurement object 4 is completed in a short time. Therefore, as shown in FIG. 7, the reference potential signal S7 converges within a deviation corresponding to the current gain of the feedback loop at time t1 with respect to the voltage V1. When overshoot occurs during convergence and the reference potential Vr exceeds the voltage V1 of the measurement object 4, the potential difference (V1−Vr) becomes a negative voltage, and thus the polarity of the polarity signal S8 also becomes negative. . Therefore, in the voltage generation unit 3b, the voltage generation circuit 27 decreases the voltage value by an amount proportional to the amplitude of the input analog signal S5 and outputs the voltage signal S6. Thereafter, the voltage measuring apparatus 1 continues the above-described feedback operation, so that the voltage value (reference potential Vr) of the reference potential signal S7 is within a certain deviation with respect to the voltage V1 of the measuring object 4 that changes. ). In this case, the reference potential signal S7 (and the voltage signal S6) is an AC signal that changes in synchronization with the voltage V1 of the measurement object 4. The voltmeter 3d measures the voltage of the reference potential signal S7 in real time, and outputs data D2 indicating the voltage value (reference potential Vr) to the processing unit 3c.

  On the other hand, the processing unit 3c periodically repeats the operation of executing the voltage measurement processing 100 shown in FIG. 8 in a short period after a lapse of time (t1-t0) from the measurement start (time t0). The short period in this example is a period that is sufficiently shorter than the fluctuation period of the voltage V1 of the measurement object 4, and refers to a period during which the voltage V1 can be regarded as a substantially constant value. In the voltage measurement process 100, the processing unit 3c first executes a first voltage acquisition process (step 101). In this voltage acquisition process, the processing unit 3c acquires the voltage value (reference potential Vr) of the reference potential signal S7 when the amplification factor of the amplifier circuit 23 is Ga0 as the reference potential Vr1 before gain change from the voltmeter 3d. And stored in an internal memory (not shown).

  Subsequently, the processing unit 3c executes a gain changing process (step 102). In the gain changing process, the processing unit 3c outputs the control signal S12 to the amplifier circuit 23. As a result, the amplifier circuit 23 changes the initial gain Ga0 to a gain Ga1 that is α times the initial gain Ga0. Therefore, the gain of the control unit 3a is multiplied by α, and as a result, the gain of the feedback loop is also changed to a gain that is α times the gain before the change. In addition, it can replace with the structure which changes the gain of the control part 3a, and can also be set as the structure which changes the gain of the voltage generation part 3b or the probe unit 2. FIG. As an example, as indicated by a broken line in FIG. 1, the processing unit 3 c may change the gain of the voltage generation circuit 27 to change the gain of the feedback loop of the voltage measurement device 1. Further, although not shown, the gain of the feedback loop may be changed by providing an amplifier circuit other than the amplifier circuit 23 in the feedback controller FC and changing the gain of the amplifier circuit. Furthermore, the voltage value of the drive signal S1 output to the variable capacitance circuit 19 can be changed.

  Next, the processing unit 3c executes a second voltage acquisition process (step 103). In this voltage acquisition process, the processing unit 3c changes the gain of the voltage value (reference potential Vr) of the reference potential signal S7 after the gain of the feedback loop is changed (when the amplification factor of the amplifier circuit 23 is Ga1). Is obtained from the voltmeter 3d as a reference potential (reference potential at high gain) Vr2 and stored in the internal memory. The processing unit 3c returns the gain of the feedback loop to the initial gain Ga0 by stopping the output of the amplifier circuit 23 to the control signal S12 after the completion of the second voltage acquisition process.

  Subsequently, the processing unit 3c executes a change rate calculation process (step 104). In the change rate calculation process, the processing unit 3c calculates the difference ΔVr (= Vr2−Vr1) by subtracting the reference potential (reference potential at the time of low gain) Vr1 from the reference potential Vr2 stored in the internal memory. And stored in the internal memory. Further, by dividing this difference ΔVr by either one of the reference potentials Vr1 and Vr2 (in this example, the reference potential Vr2 at the time of high gain), the rate of change H (= ΔVr / Vr2) is calculated to be internal. Store in memory. Next, the processing unit 3c executes a quality determination process (step 105). In this pass / fail determination process, the processing unit 3c compares the change rate H stored in the internal memory with the reference value Dr, and when the change rate H is equal to or greater than (or exceeds) the reference value Dr, feedback after the change. When it is determined that the gain of the loop is not good (the gain is not sufficient), and when the change rate H is less than (or less than) the reference value Dr, the gain of the feedback loop after the change is good (the gain is sufficient). Is determined). Further, the processing unit 3c stores this determination result in the internal memory.

  In the feedback control, when both the gains before and after the change of the feedback loop are sufficient, the reference potentials Vr1 and Vr2 measured at each gain are both values close to the voltage V1 of the measuring object 4 as a result. The change rate H of the potential Vr becomes small. On the other hand, when each gain of the feedback loop before and after the change is not good, or when the gain of the feedback loop after the change is not sufficient, the reference potential is not enough. The change rate H of Vr becomes a large value. For this reason, for example, simulations and experiments are performed to calculate the reference potentials Vr1 and Vr2 when the gain of the feedback loop is good, and the rate of change H is obtained from both, and the obtained value is used as the reference value Dr. Thus, it is possible to determine whether or not the gain of the feedback loop is good by comparing the reference value Dr with the change rate H.

  Subsequently, the processing unit 3c determines whether or not to execute the voltage calculation process based on the result of the quality determination process stored in the internal memory (step 106), and the gain of the feedback loop after the change is good. When it is determined that there is, a voltage calculation process is executed (step 107).

In this voltage calculation process, the processing unit 3c first calculates an error rate e based on the following formula (1) from the change rate H and the magnification α stored in the internal memory.
Error rate e = H / (α-1) (1)
In this example, as described above, in the change rate calculation process, the change rate H (= ΔVr / Vr2) at the time of high gain is calculated by dividing the difference ΔVr by the reference potential Vr2 at the time of high gain. Therefore, the error rate e2 when the feedback loop is at a high gain (when the gain is multiplied by α) is calculated as the error rate e.

Here, the equation (1) will be described. As shown in FIG. 9, the voltage measuring apparatus 1 shown in FIG. 1 takes the voltage V1 as an input, and outputs a reference potential Vr that is an output as a difference U (which is also an output error with respect to the input. It can be regarded as a model that performs feedback control so as to approach zero. For this reason, when the gain before change of the entire feedback control unit FC configured by the probe unit 2, the control unit 3a, and the processing unit 3c is G, the following equations (2) and (3) hold.
U = V1-Vr1 (2)
Vr1 = G × U (3)
At this time, when the ratio of the error U to the input V1 is considered as the error rate e1, the error rate e1 is expressed by the following equation (4).
Error rate e1 = U / V1 = 1 / (1 + G) (4)

On the other hand, since the gain after the change of the entire feedback control unit FC is α × G after the gain change, the following equations (5) and (6) are established.
U = V1-Vr2 (5)
Vr2 = α × G × U (6)
At this time, when the ratio of the error U to the input V1 is considered as the error rate e2, the error rate e2 is expressed by the following equation (7).
Error rate e2 = U / V1 = 1 / (1 + α × G) (7)

Next, when the difference between the error rates e1 and e2 is ε, ε is expressed by the following equation (8).
ε = e1-e2
= (V1-Vr1) / V1- (V1-Vr2) / V1
= 1 / (1 + G) -1 / (1 + α × G)
= (Α-1) × G / (1+ (α + 1) × G + α × G ² ) (8)
Note that ε is also expressed by the following formula (9).
ε = e1-e2
= (V1-Vr1) / V1- (V1-Vr2) / V1
= (-Vr1 + Vr2) / V1
= ΔVr / V1 (9)

By the way, the gain G is normally set to a value of about several hundreds to several hundreds and is sufficiently larger than the numerical value 1 (G >> 1). Further, since the magnification α may be about 2 to 3, G is a sufficiently large value in relation to the magnification α. Therefore, the above equation (8) can be approximated as the following equation (10).
ε≈ (α−1) × (1 / (1 + α × G)) (10)
Further, (1 / (1 + α × G)) in the right equation of the equation (10) is an error rate e2 from the equation (7), and is further expressed as the following equation (11).
ε≈ (α-1) × e2 (11)
When the gain G is G >> 1 as described above, the reference potentials Vr1 and Vr2 do not completely coincide with the voltage V1, but are close to the voltage V1 to such an extent that they can be regarded as the voltage V1. However, it is considered that the reference potential Vr2 after the gain change (α × G) is closer to the voltage V1. Therefore, by setting V1 in the above formula (9) to a reference potential at the time of high gain (reference potential Vr2 in this example) of the reference potentials Vr1 and Vr2, ε is approximated as the following formula (12). This is consistent with the rate of change H calculated in step 104.
ε≈ΔVr / Vr2 (= H) (12)
Therefore, based on the above equations (11) and (12), the error rate e2, that is, the error rate e when the gain is increased, is expressed by the above equation (1).

Finally, in this voltage calculation process, the processing unit 3c uses the error rate e (e2 in this example) calculated by the above formula (1) based on the change rate H and the magnification α, and the measured reference potential Vr2 as follows: By substituting into the equation (13), the voltage V1 is calculated and stored in the internal memory. Thereby, the voltage calculation process is completed.
V1 = Vr2 / (1-e2) (13)
Here, this equation (13) is derived from the above equations (5) and (7) that are satisfied after the gain change, that is, when the gain is increased. Therefore, based on the reference potential Vr1 measured before changing the gain of the feedback control unit FC, the reference potential Vr2 measured after multiplying the gain by α, and the known magnification α, feedback control before and after the change is performed. It is understood that the voltage V1 of the measurement object 4 can be directly calculated under the condition that the gain of the part FC is good.

  When the voltage calculation process in step 107 is completed, and when it is determined in step 106 that the gain of the feedback loop after the change is not good, the processing unit 3c executes an output process (step 108). In this output process, when executing the voltage calculation process, the processing unit 3c performs the voltage calculation process together with the result of the pass / fail determination process executed in step 105 (the result indicating that the gain of the feedback loop after the change is good). Data D1 indicating the result (calculated voltage V1) is output to the output unit 3e. In this case, the output unit 3e displays the voltage V1 together with the character information “good gain”. On the other hand, when the voltage calculation process is not executed, the processing unit 3c outputs the data D1 indicating the result of the pass / fail determination process executed in step 105 (the result that the gain of the feedback loop after the change is not good) as the output unit 3e. Output to. In this case, the output unit 3e displays the character information “Gain is not good”. Thereby, one voltage measurement process is completed.

  As described above, since the processing unit 3c periodically repeats the operation of executing the voltage measurement processing 100 in a short period, when the gain of the feedback loop of the feedback control unit FC is good, the output unit 3e Along with the character information indicating that the gain is good, the voltage V1 of the measuring object 4 is continuously displayed in a predetermined cycle. Thereby, even if the voltage V1 of the measurement object 4 is a DC voltage, even if it is an AC voltage that changes periodically or a voltage that changes irregularly, the voltage V1 is displayed on the output unit 3e. .

  On the other hand, when the gain of the feedback loop of the feedback control unit FC is not good, only the character information indicating that is continuously displayed on the output unit 3e. For this reason, the operator can determine that the gain of the feedback loop of the feedback control unit FC is not preferable, and to improve (improve) the current feedback loop gain (that is, the measurement condition), for example, Operations such as adjusting the positional relationship between the probe unit 2 and the measurement object 4 can be performed.

  Thus, according to the voltage measurement device 1, the measurement method executed by the voltage measurement device 1, and the program executed by the voltage measurement device 1, the gain of the feedback loop for the feedback control unit FC is changed and changed. The difference ΔVr between the two reference potentials Vr1 and Vr2 measured before and after is divided by one of the two reference potentials Vr1 and Vr2 (the reference potential Vr2 in this example), and the change rate H (calculated value) When the change rate H is equal to or greater than a predetermined reference value Dr, it is determined that the feedback control (that is, the measurement condition) is not good (defective), and a message to that effect is output. By executing output processing that determines that the feedback control is good when it is less than the value Dr and outputs that effect, in other words, two references Whether or not the feedback control is good based on the output result by determining whether or not the operation state of the feedback control of the voltage measuring device 1 is good based on the positions Vr1 and Vr2 and outputting (displaying) the result. As a result, for example, it is possible to recognize whether or not the measured voltage V1 is reliable. As a result, the voltage measurement device 1 can measure the voltage of the measurement object 4. Reliability can be ensured.

  As a result of comparison between the change rate H and the reference value Dr, instead of the configuration that determines whether the feedback control is good or not and outputs the result based on the comparison between the change rate H and the reference value Dr. It is also possible to adopt a configuration that outputs only Even in this configuration, the operator can determine that the feedback control (that is, the measurement condition) is not good (defective) based on the output indicating that the change rate H is equal to or greater than the reference value Dr, and the change rate H is the reference. Based on the output indicating that the value is less than the value Dr, it can be determined that the feedback control is good, and thus the reliability of the voltage measured by the voltage measuring device 1 can be ensured.

  Further, according to the voltage measuring apparatus 1, by outputting the pass / fail result of the feedback control to the output unit 3e such as a display device, the output unit 3e outputs the pass / fail result of the feedback control, that is, the reliability of the voltage measured by the voltage measuring apparatus 1. Therefore, it is possible to save the trouble of connecting another output device to the voltage measuring device 1.

  Further, according to the voltage measurement device 1, the measurement method executed by the voltage measurement device 1, and the program executed by the voltage measurement device 1, the rate of change H and the gain ratio α after change with respect to the gain before change are obtained. By calculating the voltage V1 of the measurement object 4 based on the reference physical quantity at the time of high gain of the two reference potentials Vr1 and Vr2, the reliability of the voltage measurement device 1 for measuring the voltage of the measurement object 4 is calculated. (Measurement accuracy) can be improved.

  Furthermore, in this voltage measuring apparatus 1, a voltage generator 3b that generates a reference potential Vr corresponding to the voltage V1 of the measurement object 4 and a potential difference (difference U) between the voltage V1 of the measurement object 4 and the reference potential Vr. ) And a control unit 3a that changes the reference potential Vr with respect to the voltage generation unit 3b so that the amplitude of the detection signal S3 is decreased. The control unit FC is configured, and the gain of the feedback loop of the feedback control unit FC is changed by controlling the gain of at least one of the control unit 3a, the voltage generation unit 3b, and the probe unit 2 by the processing unit 3c. Therefore, according to the voltage measuring device 1, the gain of the feedback loop of the feedback control unit FC can be changed automatically and in a short time, so that the voltage measuring device 1 can be used even when the voltage V1 of the measuring object 4 varies. The voltage V1 can be measured in real time while ensuring the reliability of the voltage measurement of the measurement object 4 by the above.

  Further, in this voltage measuring apparatus 1, a detection electrode 12 that can be opposed to the measurement object 4, a variable capacitance circuit 19 that is connected to the detection electrode 12 and configured to change its capacitance C1, and a current detector The probe unit 2 is configured as a sensor unit. Therefore, according to the voltage measuring apparatus 1, the detection object 12 is disposed on the surface of the probe unit 2, and the measurement object is disposed in the state where the variable capacitance circuit 19 and the current detector 15 are disposed inside the probe unit 2. 4 can be measured, and thus the probe unit 2 can be configured without providing a hole for directly facing the variable capacitance circuit 19 to the measurement object 4. Therefore, according to the voltage measuring apparatus 1, a situation in which foreign matter is erroneously inserted into the probe unit 2 through the hole and damage to parts in the probe unit 2 due to the erroneous insertion are reliably avoided. Therefore, it is possible to improve the reliability of the entire apparatus while ensuring the reliability of the voltage measurement of the measurement object 4 by the voltage measuring apparatus 1.

  In addition, according to the voltage measuring apparatus 1, the variable capacitance circuit 19 is configured including the first electrical element E1 whose capacitance changes according to the magnitude of the absolute value of the applied voltage while preventing the passage of a DC signal. As a result, the capacitance C1 can be changed at a frequency f2 that is twice the frequency f1 of the drive signal S2, and as a result, the capacitance C2 between the measurement object 4 and the case 11 can be changed at the frequency f2. Can do. Therefore, according to the voltage measuring apparatus 1, since the response speed of the feedback loop of the current detector 15 to the voltage generator 3b (the voltage generator circuit 27 and the transformer Tr3) can be increased, the reference potential signal S7 (reference potential Vr) is generated. The voltage V1 can be accurately followed, and as a result, the voltage V1 of the measurement object 4 can be accurately measured. As a result, the voltage measurement device 1 can sufficiently measure the voltage of the measurement object 4 with sufficient reliability. Can be secured.

  Further, according to the voltage measuring apparatus 1, the variable capacitance circuit 19 is configured by including the four first electric elements E1 connected in a bridge shape, and the variable capacitance circuit 19 satisfies the equilibrium condition as the bridge circuit. By setting each impedance of each first electrical element E1 so that the variable capacitance circuit 19 is applied with the drive signal S2 between its connection points B and D, the voltage of the drive signal S2 In a state where a component (a voltage signal having the same frequency f1 as that of the drive signal S2) is hardly generated between the connection points A and C (a state where a voltage signal having a very low level is generated even if it occurs), The capacitance C1 can be changed at the period T2. Therefore, according to the voltage measuring apparatus 1 using the variable capacitance circuit 19, the influence of the drive signal S2 on the current i generated in the variable capacitance circuit 19 when the capacitance changes can be eliminated. As a result of being able to detect more accurately in the unit 2 and thereby measuring the voltage V1 of the measurement object 4 more accurately, the reliability of the voltage measurement of the measurement object 4 by the voltage measurement device 1 is improved. It can be secured sufficiently.

In addition, this invention is not limited to said structure. For example, in the voltage measuring apparatus 1 described above, when the magnification α is “2”, the error rate e2 (that is, the error rate e at the time of high gain) is changed from the above equation (1) to the following equation (14). expressed.
e2 = (Vr2-Vr1) / Vr2 (14)
Accordingly, the above equation (13) for calculating the voltage V1 is expressed as the following equation (15).
V1 = Vr2 / (1- (Vr2-Vr1) / Vr2)
= Vr2 × (Vr2 / Vr1) (15)

On the other hand, the above equation (15) uses the rate of change H obtained by dividing the difference ΔVr (= Vr2−Vr1) by the reference potential Vr2 of the reference potentials Vr1 and Vr2, but see the difference ΔVr. It is also possible to use a rate of change H (= ΔVr / Vr1) divided by the potential Vr1. In this case, the error rate e2 is expressed as the following formula (16), and thus the formula (13) for calculating the voltage V1 is expressed as the following formula (17). .
e2 = (Vr2-Vr1) / Vr1 (16)
V1 = Vr2 / (1- (Vr2-Vr1) / Vr1)
= Vr2 / (1- (Vr2 / Vr1-1))
Here, since (Vr2 / Vr1-1) << 1, the voltage V1 is approximated by the following equation.
V1≈Vr2 × (1+ (Vr2 / Vr1-1))
= Vr2 × (Vr2 / Vr1) (17)

  Thus, as is clear from the above equations (15) and (17), when the magnification α is “2”, the voltage V1 can be calculated by multiplying (Vr2 / Vr1) by Vr2. . Therefore, in the voltage measuring apparatus 1 described above, the reference physical quantity Vr2 at the time of high gain of the two measured reference physical quantities Vr1 and Vr2 is divided by the reference physical quantity Vr1 at the time of low gain, and a calculated value ( A configuration in which the voltage V1 is calculated based on Vr2 / Vr1) and the reference physical quantity Vr2 at the time of high gain can also be adopted.

  Further, for example, in the voltage measuring device 1 described above, as a method of changing the gain of the feedback loop, a method of changing the amplification factor for a signal (analog signal S5, voltage signal S6, etc.) in the feedback loop of the voltage measuring device 1 is used. Although employed, a method of changing the effective area of the detection electrode 12 with respect to the measurement object 4 or changing the coupling distance of the detection electrode 12 with respect to the measurement object 4 can also be adopted. In this case, as a configuration for changing the effective area of the detection electrode 12 with respect to the measurement object 4, a configuration in which the detection electrode 12 is configured by a plurality of electrodes and the number of the electrodes is changed, or a shielding member is provided on the surface of the detection electrode 12. It is possible to adopt a configuration in which the area (shielding area) of the detection electrode 12 covered with the shielding member is changed by arranging the above. Further, as a configuration for changing the coupling distance of the detection electrode 12 to the measurement object 4, a configuration in which the detection electrode 12 is driven by a ball screw or the like can be employed. Further, in the voltage measuring apparatus 1 described above, the processing unit 3c employs a configuration in which the gain of the feedback loop is automatically changed. However, the operator may manually change the gain of the feedback loop. .

  Moreover, in the voltage measuring apparatus 1 described above, as shown in FIGS. 2 to 5, all the structural units 31 to 34 are configured so as to include only the first electrical elements E11 to E14, respectively, but the present invention is not limited thereto. In the capacity change function body 13 shown in each drawing, the set of the first structural unit 31 and the fourth structural unit 34 among the first to fourth structural units 31 to 34, and A second electrical element that allows passage of an AC signal as the first electrical element included in each of the constituent units of one set of the second constituent unit 32 and the third constituent unit 33 It is also possible to configure a capacity change function body by replacing with. In this case, the second electrical element includes at least one of a capacitor, a coil, a resistor, and a resonator. As an example, the capacity change function body 13A shown in FIG. 10 uses the second electrical unit E12, E13 of the second structural unit 32 and the third structural unit 33 in the capacity change function body 13 shown in FIG. The second structural unit 32A and the third structural unit 33A are configured to be replaced by electrical elements E22 and E23 (capacitors 62 and 63 having the same electrical characteristics), respectively. Instead of the capacitors 62 and 63, a pair of coils 62a and 63a having the same electrical characteristic (inductance value) may be used, or a pair of resistors 62b and 63b having the same electrical characteristic (resistance value) may be used. Alternatively, a pair of resonators 62c and 63c having the same electrical characteristics (frequency-impedance characteristics) may be used. In this case, the resonators 62c and 63c have a minimum impedance at a frequency (capacitance modulation frequency) f2 that is twice the frequency f1 of the drive signal S2, and a sufficiently high impedance at other frequencies. Use a resonator with electrical characteristics. Specifically, various resonators such as a ceramic resonator, a crystal resonator, and an LC resonance circuit (series resonance circuit) including a coil and a capacitor can be used. Further, the resonators 62c and 63c may be configured to allow a direct current to pass therethrough.

  Moreover, in the capacity | capacitance change function body 13 shown in FIGS. 2-5, the group of the 1st structural unit 31 of the 1st-4th structural units 31-34, and the 2nd structural unit 32, and 3rd The first electrical element E1 included in each structural unit of one set of the structural unit 33 and the fourth structural unit 34 is allowed to pass an AC signal while preventing the DC signal from passing therethrough. It is also possible to configure a capacity change function body by replacing with a third electric element to be allowed. In this case, the third electrical element includes at least one of a capacitor and a resonator. As an example, the capacity change function body 13B shown in FIG. 11 uses the third electrical unit E13, E14 of the third structural unit 33 and the fourth structural unit 34 in the capacity change function body 13 shown in FIG. The third structural unit 33B and the fourth structural unit 34A are configured to be replaced by electrical elements E33 and E34 (capacitors 63 and 64 having the same electrical characteristics as an example). Instead of the capacitors 63 and 64, a pair of resonators 63d and 64a having the same electrical characteristics (frequency-impedance characteristics) may be used. In this case, the resonators 63d and 64a have a minimum impedance at a frequency (capacitance modulation frequency) f2 that is twice the frequency f1 of the drive signal S2, and a sufficiently high impedance at other frequencies. Use a resonator with electrical characteristics. Specifically, various resonators such as a ceramic resonator, a crystal resonator, and an LC resonance circuit (series resonance circuit) including a coil and a capacitor can be used. The resonators 63d and 64a are configured to block the passage of direct current.

  10 and 11 are not limited to the above-described configuration, and are not shown in the figure. For example, the first electric elements E11, E12, and E14 are variable capacitance diodes. Instead, it may be configured by a general diode (silicon diode), or may be configured by a pair of diodes (variable capacitance diode or silicon diode) in which the cathode terminals are connected and connected in series.

  Further, in the capacitance change function body 13 shown in FIG. 4, each of the structural units 31 to 34 is configured by a pair of first elements 51 (specifically, general diodes), but each of the structural units 31 to 34 is configured. Are connected in series in opposite directions by connecting the anode terminals to each other. That is, each of the structural units 31 to 34 is configured by arranging a P-type semiconductor and an N-type semiconductor in the form of N-P-P-N. Therefore, by replacing the pair of first elements 51 (diodes) constituting each of the structural units 31 to 34 with one NPN type bipolar transistor TR1 to TR4 in the capacitance changing function body 13 shown in FIG. Each of the first electric elements E11 to E14 included in .about.34 can be configured by one transistor to form the capacitance changing function body 13C shown in FIG. In this capacitance change function body 13C, each of the transistors TR1 to TR4 has its input terminal (one of the collector terminal and the emitter terminal) and its output terminal (the other of the collector terminal and the emitter terminal) connected to each other (respectively connected to the connection point). It is arranged in an annular path composed of the respective structural units 31 to 34. Note that the control terminals (base terminals) of the transistors TR1 to TR4 are not connected (does not become connection points).

  Further, in the capacity change function body 13 shown in FIG. 4, the structural units 31 and 34, the structural units 31 and 32, the structural units 32 and 33, and the structural units 33 and 33 are sandwiched between the connection points A, B, C, and D. One diode included in each of the first electric elements E1 of 34 is adjacent to each other (specifically, the diodes are connected in series in opposite directions to each other). In this way, the first electric element E1 is constituted by a pair of diodes connected in series in opposite directions, and the capacitance changing function body 13 in which at least two adjacent structural units include the first electric element E1. Then, one diode included in each first electrical element E1 is connected in series in opposite directions with a connection point between the two structural units interposed therebetween. Therefore, as shown in FIG. 13, the capacitance changing function body 13D can be configured by replacing a pair of diodes surrounded by a broken line with one PNP-type bipolar transistor TR5 to TR8. In this case, each first electrical element E1 is composed of a part of one transistor and a part of the other one transistor. In the capacitance change function body 13D, each of the transistors TR5 to TR8 has an input terminal (one of the collector terminal and the emitter terminal) and an output terminal (the other of the collector terminal and the emitter terminal) in the same manner as the capacitance change function body 13C. Are connected to each other (each as a connection point) and arranged in an annular path constituted by the respective structural units 31 to 34. On the other hand, the control terminals (base terminals) of the transistors TR5 to TR8 are used as connection points A, B, C, and D, unlike the capacitance change function body 13C.

  Moreover, about the capacity | capacitance change functional body 13 shown in FIG. 5 by which each 1st electrical element E11-E14 of each structural unit 31-34 is comprised with a pair of diodes which cathode terminals were connected and connected mutually in series. Similarly to the capacitance changing function body 13 shown in FIG. 4, the capacitance change shown in FIG. 14 is obtained by replacing the pair of diodes constituting the first electric elements E11 to E14 with PNP bipolar transistors TR5 to TR8. The functional body 13E can be configured, and each pair of diodes described above (four pairs each composed of a pair of diodes adjacent to each other with the connection points A, B, C, and D interposed therebetween) is an NPN bipolar. By replacing the transistors TR1 to TR4, the capacitance changing function body 13F shown in FIG. 15 can be configured. Moreover, although the example which uses a bipolar transistor as a transistor is demonstrated, it replaces with an NPN type bipolar transistor, may use the same type MOSFET (field effect type transistor), or replace with a PNP type bipolar transistor. Of course, the same type of MOSFET (field effect transistor) may be used. In this case, the input terminal of the MOSFET is one of the drain terminal and the source terminal, and the output terminal is the other of the drain terminal and the source terminal. 13 and 15, gate terminals as control terminals are used as connection points A, B, C, and D. In this way, by configuring the first electrical element E1 using the transistors TR1 to TR4 (or TR5 to TR8), the capacitance changing functional units 13C to 13F can be configured easily and inexpensively with a smaller number of parts. Can do.

  In addition, unlike the voltage measuring device 1A shown in FIG. 16, the capacity change function bodies 13, 13A,..., 13F (if not particularly distinguished from each other) are not provided with the current detector 15. The probe unit 2A (sensor unit) can also be employed as the detection signal S3 by detecting the voltage V3 between the two terminals V). Here, the voltage V3 between both ends of the capacitance change function body 13 is the end portion (connection point A) on the detection electrode 12 side in the capacitance change function body 13 and the end portion (connection) on the case 11 side in the capacitance change function body 13. This is the voltage generated between the point C). In this case, one input terminal of the pair of input terminals in the preamplifier 16 is connected to the end of the capacitance changing function body 13 on the detection electrode 12 side via the capacitor 17 as shown in FIG. The input terminal is connected to the end of the capacitance changing function body 13 on the case 11 side. Since the voltage measuring device 1A is the same as the voltage measuring device 1 except for this configuration, the same components as those of the voltage measuring device 1 are denoted by the same reference numerals in FIG. A duplicate description is omitted. Also in this voltage measuring device 1A, the influence of the drive signal S2 on the voltage V3 across the variable capacitance circuit 19 is eliminated, so that the main unit 3 is set to the voltage V1 of the measurement object 4 based on the voltage V3 across the voltage. As a result of being able to accurately follow the reference potential signal S7, the voltage V1 of the measurement object 4 can be accurately measured.

  In the voltage measuring apparatus 1, the current detector 15 is disposed between the variable capacitance circuit 19 and the case 11, but the current detector 15 is disposed between the detection electrode 12 and the variable capacitance circuit 19. You can also In the voltage measuring devices 1 and 1A, the filter circuit 22, the amplifier circuit 23, and the detection circuit 24 are configured to operate with analog signals. However, the filter circuit 22, the amplifier circuit 23, the detection circuit 24, and the polarity determination circuit 25 are used. Further, the processing unit 3c may be configured by one or a plurality of DSPs (Digital Signal Processors).

  As shown in FIGS. 2 to 5 and FIGS. 10 to 15, each structural unit of each capacitance changing function body 13 is connected in series in the first electrical element E1 (as an example, opposite to each other). A description will be given of an example constituted by two diodes (equivalently two diodes in the case of FIGS. 12 to 15), the second electrical elements E22 and E23, and the third electrical elements E33 and E34. However, the present invention is not limited to this. For example, taking the first structural unit 31 shown in FIG. 2 as an example and describing the structural unit including the first electrical element E11, other than the first electrical element E11 together with one first electrical element E11. The 1st structural unit 31 can also be comprised including a component. Specifically, at least one of a resistor, a capacitor, a coil, and another diode is disposed between at least one of the connection point A and the first element 41a and between the connection point B and the first element 41b. You can also In addition, the first electrical element E1 can be configured to include components other than the first elements 41a and 41b. Specifically, at least one of a resistor, a capacitor, and a coil may be disposed between the first elements 41a and 41b to constitute the first electrical element E1. Further, a capacitor can be connected in parallel to each of the first elements 41a and 41b and at least one of the first elements 41a and 41b as a whole.

  Further, for example, the structural unit including the second electrical element E22 (E23) will be described by taking the structural unit 32A shown in FIG. 10 as an example, and the connection between the connection point B and the second electrical element E22 and the connection. At least one of a resistor, a capacitor, and a coil may be disposed at least one between the point C and the second electrical element E22. In addition, a capacitor can be connected in parallel to the second electrical element E22. Further, for example, taking the structural unit 33B shown in FIG. 11 as an example, the structural unit including the third electrical element E33 (E34) will be described. Between the connection point C and the third electrical element E33, and the connection At least one of a resistor, a capacitor, and a coil may be disposed at least one between the point D and the third electrical element E33. Also, another capacitor can be connected in parallel to the third electrical element E33.

  Further, since the basic configuration of both the variable capacitance diode and the general diode is the same, for example, in the capacitance change function body 13 shown in FIG. 2, as the first elements 41a and 41b constituting each first electrical element E1. A variable capacitance diode and a general diode can be mixed and used, for example, one of the variable capacitance diodes is configured using a general diode. However, a variable capacitance diode and a general diode have different electrostatic capacities when a reverse bias is applied, so that they satisfy the equilibrium condition of the bridge circuit and are arranged on both sides of the connection points A and C as a reference. The respective structural units 31, 32 and the respective structural units 34, 33 that are provided are line-symmetric or each of the structural units 31, 34, 34 and 33 that are disposed on both sides with respect to the connection points B, D. It is necessary to configure so that the structural units 32 and 33 are line-symmetric.

  In the voltage measuring devices 1, 1A and the like described above, the transformer Tr2 is used as the current detector 15. However, a resistor or a resonator is used, and the voltage between both ends is input to the preamplifier 16 as the voltage V2. Can also be adopted.

  The variable capacitance circuit according to the present invention is not limited to the configuration using a diode or the like as described above. For example, the configuration disclosed in Japanese Patent Laid-Open No. 6-242166 described as a conventional example, Also, a mechanical configuration using a piezoelectric tuning fork and a detection electrode (an electrode corresponding to the detection electrode 12 of the present application) can be employed. Furthermore, the configuration disclosed in Japanese Patent Laid-Open No. 4-305171, that is, a configuration including a detection electrode and a vibrating body (not shown) may be used. In the variable capacitance circuit (variable capacitance mechanism) with this configuration, the detection electrode (an electrode different from the detection electrode 12) is brought into contact with and separated from the detection electrode 12 by the vibrating body, so that the capacitance C1, that is, The capacitance C1 between the detection electrode and the detection electrode 12 changes. The variable capacitance circuit uses the configuration disclosed in Japanese Patent Laid-Open No. 7-244103, that is, a configuration (not shown) including a conductor sector and a detection electrode (an electrode different from the detection electrode 12). It can also be configured. In the variable capacitance circuit (variable capacitance mechanism) having this configuration, the detection electrode is arranged to face the detection electrode 12 and a conductor sector is arranged between the two electrodes. In this state, the conductor sector is detected from the detection electrode 12. By repeatedly shielding and opening the lines of electric force reaching the electrodes, the capacitance C1, that is, the capacitance C1 between the detection electrode 12 and the detection electrode changes. Furthermore, the variable capacitors disclosed in JP-A-8-181038 and JP-A-9-153436, that is, between the two electrodes by elastically deforming at least one of a pair of electrodes arranged in proximity to each other. A variable capacitor (none of which is shown) that changes the capacitance C1 by changing the distance can be used as the variable capacitance circuit.

  In addition, the voltage measuring devices 1 and 1A described above may be configured as a voltage measuring device alone, applied to a current measuring device, and applied to a power measuring device combined with a known current measuring device. Can be applied to the measuring device.

1 is a block diagram of a voltage measuring device 1. FIG. It is a circuit diagram of the capacity | capacitance change functional body 13 of FIG. It is another circuit diagram of the capacity | capacitance change function body 13 of FIG. It is another circuit diagram of the capacity | capacitance change function body 13 of FIG. It is another circuit diagram of the capacity | capacitance change function body 13 of FIG. 6 is a relationship diagram between a drive signal S2 and a capacitance C2 for explaining the operation of the capacitance change function body 13. FIG. It is a wave form diagram which shows the relationship between the voltage V1 and reference potential signal S7. 3 is a flowchart of a voltage measurement process 100. 1 is a model diagram of a voltage measuring device 1. FIG. It is a circuit diagram of capacity change functional body 13A. It is a circuit diagram of capacity change function body 13B. It is a circuit diagram of capacity change functional body 13C. It is a circuit diagram of capacity change functional body 13D. It is a circuit diagram of capacity change function body 13E. It is a circuit diagram of capacity change function body 13F. It is a block diagram of voltage measuring device 1A.

Explanation of symbols

1,1A Voltage measurement device 2 Probe unit (sensor unit)
DESCRIPTION OF SYMBOLS 3 Main body unit 3a Control part 3b Voltage generation part 3c Processing part 3d Voltmeter 3e Output part 4 Measurement object 11 Case 12 Detection electrode 14 Drive circuit 15 Current detector 19 Variable capacity circuit 100 Gain setting process E11-E14 1st electrical Element E22, E23 Second electrical element E33, E34 Third electrical element Tr3 Transformer S3 Detection signal V1 Voltage of measurement object Vr Reference potential

Claims (7)

A reference physical quantity corresponding to a physical quantity of a measurement object is generated by feedback control so that a difference from the physical quantity is reduced, and the measurement apparatus calculates the physical quantity of the measurement object based on the reference physical quantity,
By changing the gain of the feedback control to measure the reference physical quantity before and after of the change in the calculated value obtained by dividing the either one of the measured two reference physical quantity of the difference of the two reference physical quantity in advance In a state where the gain of the feedback control that is less than a determined reference value is in a good state, the calculated value, the gain ratio after the change with respect to the gain before the change, and the high gain of the two reference physical quantities A measurement device that calculates the physical quantity of the measurement object based on a reference physical quantity at the time. A reference physical quantity corresponding to a physical quantity of a measurement object is generated by feedback control so that a difference from the physical quantity is reduced, and the measurement apparatus calculates the physical quantity of the measurement object based on the reference physical quantity,
By changing the gain of the feedback control twice to measure the reference physical quantity before and after of the change, divides the reference physical quantity at the time of high gain of the two reference physical quantity the measurement with the reference physical quantity at the time of low gain In the state where the calculated gain is less than a predetermined reference value and the gain of the feedback control is good , based on the calculated value and the reference physical quantity at the time of the high gain, the physical quantity of the measurement object is calculated. Measuring device to calculate.   The measurement apparatus according to claim 1, wherein the calculated physical quantity is output to an output unit. A reference physical quantity corresponding to a physical quantity of a measurement object is generated by feedback control so that a difference from the physical quantity is reduced, and a measurement method for calculating the physical quantity of the measurement object based on the reference physical quantity,
Wherein by changing the gain of the feedback control to measure the reference physical quantity before and after of the changes, the difference between the two reference physical quantity the measurement is divided by either one of the two reference physical quantity, by the division In a state where the calculated control value is less than a predetermined reference value and the gain of the feedback control is good, the calculated value, the multiplication factor of the gain after the change with respect to the gain before the change, and the two A measurement method for calculating the physical quantity of the measurement object based on a reference physical quantity at the time of high gain among the reference physical quantities. A reference physical quantity corresponding to a physical quantity of a measurement object is generated by feedback control so that a difference from the physical quantity is reduced, and a measurement method for calculating the physical quantity of the measurement object based on the reference physical quantity,
By changing the gain of the feedback control twice to measure the reference physical quantity before and after of the change, divides the reference physical quantity at the time of high gain of the two reference physical quantity the measurement with the reference physical quantity at the time of low gain Then, in a state where the gain of the feedback control in which the calculated value calculated by the division is less than a predetermined reference value is good , based on the calculated value and the reference physical quantity at the time of the high gain, A measurement method for calculating the physical quantity of a measurement object. On the computer,
Feedback control that generates a reference physical quantity corresponding to the physical quantity of the measurement object, detects a difference between the physical quantity of the measurement object and the reference physical quantity, and feedback-controls the reference physical quantity so that the difference decreases. and parts, the procedure for changing the gain of the feedback loop to the feedback control unit in the measurement apparatus and a measurement unit for measuring the reference physical quantity,
A procedure for obtaining the reference physical quantity before and after the change of the gain measured by the measurement unit;
A procedure for calculating a calculated value by dividing the difference between the two acquired reference physical quantities with one of the two reference physical quantities;
In a state where the gain of the feedback control in which the calculated value is less than a predetermined reference value is good, the calculated value, a ratio of the gain after the change to the gain before the change, and the two reference physical quantities A program for executing a procedure for calculating the physical quantity of the measurement object based on a reference physical quantity at high gain. On the computer,
Feedback control that generates a reference physical quantity corresponding to the physical quantity of the measurement object, detects a difference between the physical quantity of the measurement object and the reference physical quantity, and feedback-controls the reference physical quantity so that the difference decreases. and parts, the procedure for changing the gain of the feedback loop is doubled with respect to the feedback control unit in the measuring unit and the measuring device having a measuring said reference physical quantity,
A procedure for obtaining the reference physical quantity before and after the change of the gain measured by the measurement unit;
A procedure of calculating a calculated value by dividing a reference physical quantity at a high gain of the two acquired reference physical quantities by a reference physical quantity at a low gain;
In a state where the gain of the feedback control in which the calculated value is less than a predetermined reference value is good, the physical quantity of the measurement object is calculated based on the calculated value and the reference physical quantity at the time of the high gain. A program for executing the calculation procedure.

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