JP2017090052A - Measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the accuracy of a measured quantity immediately after measurement ranges are switched.SOLUTION: A measurement device of the present invention comprises: a storage unit 4 for storing a correction value Dc for each measurement range; a measurement unit 2 for measuring a voltage value Vm with a selected one measurement range, outputting a measured value Dm, measuring a reference voltage Vr with this measurement range, and outputting it as a correction value Dc used in this measurement range; and a processing unit 3 for making the measurement unit 2 select a first measurement range with which the voltage value Vm is measured and output the measured value Dm and the correction value Dc, executing a first correction value updating process to update the correction value Dc for the first measurement range in the storage unit 4 with this correction value Dc, and executing a measurement process to correct the measured value Dm with the correction value Dc for the first measurement range stored in the storage unit 4 and calculate the voltage value Vm. The processing unit 3 makes the measurement unit 2 output the correction value Dc with a second measurement range, and updates the correction value Dc for the second measurement range in the storage unit 4 in an interval during execution of the first correction value updating process and measurement process with the first measurement range.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a measurement apparatus configured to be able to measure a measurement target to be measured in a measurement range selected from a plurality of types of measurement ranges.

  This type of measurement apparatus generally includes a measurement unit that measures a measurement voltage that changes according to a measurement target to be measured in a selected measurement range, and converts the measurement voltage into a measurement value and outputs the measurement value. In this measurement unit, the offset voltage and the gain (amplification factor) of the amplifier (amplification factor) existing in the amplifier (operational amplifier) constituting the measurement unit fluctuate according to changes in the measurement environment. For this reason, in this type of measurement apparatus, as in the measurement apparatus disclosed in Patent Document 1 below, a correction value (calibration value) for correcting the measurement value is acquired for each measurement range and stored in the storage unit. Store the measured value output from the measurement unit with the correction value corresponding to the measurement range from which the measured value was measured to obtain the final measured value (measured amount). The effect of gain variation is reduced.

  In addition, in this type of measuring device, as in the measuring device disclosed in Patent Document 2 below, correction of zero point fluctuation (offset voltage fluctuation) is automatically performed during continuous measurement of measured values. There are also things that I try to do. This measurement device periodically acquires and updates (calibrates) only the correction value (correction value for zero point) corresponding to this measurement range in the currently used measurement range among multiple measurement ranges. By doing so, the influence due to the fluctuation of the offset voltage is eliminated.

JP 2014-228503 A (page 3) Japanese Patent No. 3244212 (page 1-4, FIG. 1-8)

  However, the measuring apparatus disclosed in Patent Document 2 has the following problems to be improved. That is, as described above, this measurement apparatus is configured to update only the correction value corresponding to the measurement range in the currently used measurement range. For this reason, in this measurement apparatus, the correction value used in the measurement range other than the currently used measurement range is not updated to the latest correction value unless the correction value is switched to the measurement range to be used. . Therefore, this measuring device has an old correction value used to correct the measured value immediately after the currently used measurement range is switched to a new measurement range (another measurement range). Therefore, there is a problem that the accuracy of the final measurement value (measured amount) immediately after switching of the measurement range is lacking.

  The present invention has been made in view of such a problem to be improved, and a main object of the present invention is to provide a measuring apparatus capable of improving the accuracy of the measured amount immediately after the measurement range is switched.

  In order to achieve the above object, the measuring apparatus according to claim 1 stores a correction value for each measurement range used in a measurement process for a measurement target to be measured in a plurality of types of measurement ranges. And measuring a measurement voltage indicating the measured amount in one measurement range selected from the plurality of types of measurement ranges and outputting a measurement value, and selecting from the plurality of types of measurement ranges A measurement unit that measures a reference voltage in one measurement range and outputs it as the correction value used in the selected measurement range, and the plurality of measurement ranges as the first measurement range that causes the measurement unit to measure the measurement voltage One of the types of measurement ranges is selected and the measurement unit is made to output the measurement value and the correction value is output. To update the correction value of the first measurement range stored in the storage unit with the output correction value, and the measurement value is stored in the storage unit by executing the measurement process. And a processing unit that calculates the measured amount by correcting the measurement value with the correction value of the first measurement range, wherein the processing unit is the first measurement range. Between the execution of the first correction value update process and the measurement process, the correction value is output to the measurement unit in a second measurement range other than the first measurement range among the plurality of types of measurement ranges. And performing a second correction value update process for updating the correction value of the second measurement range stored in the storage unit with the output correction value.

  Further, in the measurement apparatus according to claim 2, in the measurement apparatus according to claim 1, the processing unit performs the second measurement on all measurement ranges except the first measurement range among the plurality of types of measurement ranges. The second correction value update process is executed as a range.

  Furthermore, in the measurement apparatus according to claim 3, in the measurement apparatus according to claim 1 or 2, the processing unit executes the second correction value update process at a frequency lower than that of the first correction value update process.

  According to the measurement apparatus of claim 1, the processing unit performs the second measurement other than the first measurement range on the measurement unit between the execution of the first correction value update process and the measurement process in the first measurement range. By executing the second correction value update process for outputting the correction value in the range and updating the correction value of the second measurement range stored in the storage unit with the correction value, the correction value is executed immediately after the measurement range is switched. As a result of using a newer correction value in the measurement process, it is possible to calculate a more accurate measured amount in a state where it is less affected by changes in the measurement environment.

  According to the measurement apparatus of the second aspect, the processing unit executes the second correction value update process using all the measurement ranges except for the first measurement range among the plurality of types of measurement ranges as the second measurement range. As a result, even if any measurement range is selected as the first measurement range, a new correction value can always be used in the measurement process executed immediately after switching the measurement range. A more accurate measurement amount can be calculated in a state where it is more difficult to be affected by the change in the above.

  Furthermore, according to the measurement apparatus of claim 3, the processing unit executes the second correction value update process at a frequency lower than that of the first correction value update process, so that it is used in the measurement process in the first measurement range. As a result of increasing the update frequency of the correction value to be used (correction value used in the measurement range selected as the first measurement range), it is possible to calculate the measured amount more accurately using the latest correction value Can do.

1 is a configuration diagram showing a configuration of a measuring device 1. FIG. 3 is a timing chart for explaining the operation of the measuring apparatus 1.

  Hereinafter, embodiments of a measuring apparatus will be described with reference to the accompanying drawings.

  First, the configuration of the measuring apparatus 1 shown in FIG. 1 as an example of the measuring apparatus will be described. The measuring apparatus 1 includes a measuring unit 2, a processing unit 3, a storage unit 4, and an output unit 5, and a measurement voltage indicating a measured amount for a measurement target (not shown) input between a pair of input terminals 6a and 6b. This measured quantity is measured based on Vin (AC or DC voltage). In this measuring apparatus 1, since the input terminal 6b is connected to a portion defined by the reference potential (ground) G in this apparatus, the measurement voltage Vin is based on the potential (reference potential G) of the input terminal 6b. Is input to the input terminal 6a.

  In this case, when the measurement voltage Vin is a signal obtained by converting the current flowing through the measurement target into a voltage, the measurement apparatus 1 measures the current as a measured quantity, and the measurement voltage Vin indicates the voltage generated in the measurement target. When it is a signal, this voltage is measured as a measured quantity. The measuring apparatus 1 receives a signal obtained by converting the current flowing through the measurement target into a voltage, and a signal indicating a voltage generated between both ends of the measurement target when the current flows, and is input in a time-sharing manner as the measurement voltage Vin. When measuring, the current flowing through the measurement object and the voltage generated at the measurement object are measured as the measured quantity, and the power calculated based on the measured current and voltage is also measured as the measured quantity. In this example, as an example, the measuring apparatus 1 is a voltage measuring apparatus that measures the voltage value Vm of the voltage generated in the measurement target as a measured quantity. As an example, the measurement voltage Vin is the same voltage as the voltage value Vm. It is assumed to be a value signal. Of course, the measurement voltage Vin may be a signal obtained by dividing the voltage generated in the measurement object or a signal obtained by boosting the voltage generated in the measurement object.

  The measurement unit 2 includes a reference voltage output unit 11, a first switch unit 12, a range amplifier 13, a preamplifier 14, and an A / D conversion unit 15. The measurement voltage Vin is a plurality of measurement ranges (in this example, 3 described later as an example). Measured value indicating the instantaneous value of this measured voltage Vin by measuring in one measurement range R selected (designated) from the two measurement ranges Ra, Rb, Rc (also referred to as measurement range R when not particularly distinguished) (Measurement data) Dm is output to the processing unit 3 at a predetermined cycle T1 (for example, at intervals of several hundred milliseconds).

  As an example, the reference voltage output unit 11 includes the same number of reference voltages Vr for gain correction (gain calibration) as the number of measurement ranges R (voltages with known reference voltage G as a reference) and offset correction (offset). One reference voltage Vrz (voltage whose voltage value is the same potential (zero volt) as the reference potential G) is output. In this example, as will be described later, since the number of measurement ranges R is three as 10V, 1V, and 0.1V as an example, the reference voltage output unit 11 uses the reference voltage Vra (for the measurement range Ra of 10V). 10V or a voltage slightly lower than 10V (for example, 9V), a reference voltage Vrb for a measurement range Rb of 1V (a voltage slightly lower than 1V or 1V, for example 0.9V), and a reference for a measurement range Rc of 0.1V The voltage Vrc (0.1 V or a voltage slightly lower than 0.1 V. For example, 0.09 V) is output as the reference voltage Vr.

  The first switch unit 12 includes a plurality of switches (in this example, five switches SW1, SW2, SW3, SW4, SW5) on / off controlled by the processing unit 3. The first switch unit 12 includes an input terminal 6a and output terminals (not shown) in the reference voltage output unit 11 (output terminals of reference voltages Vra to Vrc and Vrz) and a range amplifier 13 (non-inverting input terminal thereof). The measurement voltage Vin is selectively output to the range amplifier 13 by controlling only the switch SW1 to the on state, and the reference voltage Vra is controlled by controlling only the switch SW2 to the on state. The reference voltage Vrb is selectively output to the range amplifier 13 by selectively outputting to the range amplifier 13 and only the switch SW3 is controlled to be in the on state, and the reference voltage is being controlled by only controlling the switch SW4 to be in the on state. Vrc is selectively output to the range amplifier 13 and only the switch SW5 is controlled to be turned on so that the reference voltage Vrz is selectively supplied to the range amplifier 13. Forces.

  As an example, the range amplifier 13 includes an operational amplifier 13a, two resistors 13b and 13c for setting the gain G1, and a plurality of switches (four switches SW6 and SW7 in this example) that are turned on / off by the processing unit 3. , SW8, SW9) is provided. The non-inverting input terminal of the operational amplifier 13 a is connected to each output terminal of the first switch unit 12. The resistors 13b and 13c are connected in series with each other by connecting the other end of the resistor 13b and one end of the resistor 13c. Further, in the series circuit of the resistors 13b and 13c, one end of the resistor 13b is connected to the output terminal of the operational amplifier 13a, and the other end of the resistor 13c is regulated to the reference potential G. Between the region defined by the reference potential G in FIG.

  The switches SW6 to SW9 of the second switch section 13d are connected between the output terminal of the operational amplifier 13a and the inverting input terminal, and the switch SW7 is connected between one end of the resistor 13c and the inverting input terminal of the operational amplifier 13a. The switch SW8 is connected between the output terminal of the operational amplifier 13a and the input terminal of the preamplifier 14, and the switch SW9 is connected between one end of the resistor 13c and the input terminal of the preamplifier 14.

  With this configuration, the range amplifier 13 is controlled so that only the switches SW7 and SW8 are turned on, so that the gain G1 is set to G1c (= 10) times (that is, designated as the measurement range Rc of 0.1 V). When only SW6 and SW8 are controlled to be in the on state, the gain G1 is set to G1b (= 1) times (that is, designated as the measurement range Rb of 1V), and only the switches SW6 and SW9 are controlled to be in the on state. The gain G1 is set to G1a (= 0.1) times (that is, specified to the measurement range Ra of 10 V), and the selection voltage V1 selected by the first switch unit 12 and output from the first switch unit 12 is set. Then, it is amplified by the set gain G1 (measured in the designated measurement range R) and output to the preamplifier 14 as the first amplified voltage V2.

  The preamplifier 14 amplifies the first amplified voltage V2 output from the range amplifier 13 with a predetermined gain G2 and outputs the amplified second amplified voltage V3 to the A / D converter 15. The gain G2 of the preamplifier 14 is defined so that the voltage value of the second amplified voltage V3 can be a voltage value that conforms to the input rated voltage of the A / D converter 15.

  The A / D conversion unit 15 samples the second amplified voltage V3 output from the preamplifier 14 at a predetermined cycle T2 (for example, 1/2 of the cycle T1 described above), thereby instantaneously generating the second amplified voltage V3. Voltage data D1 indicating the value is generated and output to the processing unit 3. In this example, as will be described later, the processing unit 3 controls the first switch unit 12 such that only the switch SW1 is turned on and causes the range amplifier 13 to output the measurement voltage Vin (execution period of a measurement process Pm described later). And control of only one of the switches other than the switch SW1 to be turned on to output one type of reference voltage Vr (one of the reference voltages Vra to Vrc, Vrz). Control for the switch unit 12 (control performed during an execution period of a correction value update process Pc described later) is repeatedly executed at a cycle T2.

  With this configuration, the measurement unit 2 outputs the voltage data D1 indicating the instantaneous value of the measurement voltage Vin as the measurement value Dm at the period T1, and the reference voltage Vr is shifted from the output timing of the measurement value Dm by the period T2. Is output as a correction value Dc at a cycle T1.

  The processing unit 3 is configured by a computer, for example, and converts the measurement value Dm output from the measurement unit 2 into an individual correction value Dc (each measurement range R that is used in each measurement range R stored in the storage unit 4. Measurement process Pm (refer to FIG. 2) for measuring the voltage value Vm of the measurement voltage Vin corrected with the correction value Dc used in the measurement range R used for the measurement of the measurement value Dm. ).

  The processing unit 3 is a new correction value Dc output from the measurement unit 2, and the measurement unit 2 among the individual correction values Dc used in each measurement range R stored in the storage unit 4 A correction value updating process Pc for updating the correction value Dc used in the measurement range R used for measuring the new correction value Dc is executed.

  As the correction value Dc, a correction value Dc using voltage data D1 indicating any one of the reference voltages Vra to Vrc for gain correction and voltage data D1 indicating a reference voltage Vrz for offset correction are used. There is a correction value Dc, and in order to distinguish between the two, the former is set as the correction value Dcr and the latter is set as the correction value Dcz. Further, correction values Dcr and Dcz used in the measurement range Ra are set as correction values Dcra and Dcza, respectively, correction value update processing Pc for updating the correction value Dcra is set as correction value update processing Pcra, and correction for updating the correction value Dcza. The value update process Pc is referred to as a correction value update process Pcza. Similarly, the correction values Dcr and Dcz used in the measurement range Rb are set as the correction values Dcrb and Dczb, respectively, the correction value update processing Pc for updating the correction value Dcrb is set as the correction value update processing Pcrb, and the correction value Dczb is updated. The correction value update process Pc to be performed is referred to as a correction value update process Pczb. The correction values Dcr and Dcz used in the measurement range Rc are set as correction values Dcrc and Dczc, respectively, the correction value update processing Pc for updating the correction value Dcrc is set as the correction value update processing Pcrc, and the correction value for updating the correction value Dczc. The update process Pc is referred to as a correction value update process Pczc.

  Further, immediately after the start of the measurement process Pm and the correction value update processes Pc, the processing unit 3 performs on / off control for the switches SW1 to SW5 of the first switch unit 12 to measure the measurement voltage Vin. And one voltage used in each process Pm, Pc of each reference voltage Vr is selected and outputted to the range amplifier 13 as the selection voltage V1. Further, the processing unit 3 is suitable for calculating the voltage value Vm in the next measurement process Pm based on the voltage value Vm of the measurement voltage Vin calculated and the voltage range of each measurement range R in the measurement process Pm. One measurement range R (one measurement range for causing the measurement unit 2 to measure the measurement value Dm. This measurement range is also referred to as the first measurement range R below) and each switch of the range amplifier 13 is selected. On / off control (selection of the measurement range R for the range amplifier 13) for SW6 to SW9 is executed, and a range switching process Pr (see FIG. 2) for switching to the first measurement range R is executed.

  In addition, the processing unit 3 provides the measurement value Dm to the measurement unit 2 in one measurement range R of the plurality of types of measurement ranges R (three measurement ranges Ra, Rb, Rc in this example) in this way. When the first measurement range R to be output is selected, the voltage value Vm calculated based on the measurement value Dm in the measurement process Pm in the first measurement range R is within the voltage range of the first measurement range R. As long as the measurement process Pm is performed, the current first measurement range R is maintained without being changed, and the measurement value Dm in the first measurement range R is output to the measurement unit 2 so that the voltage value Vm is obtained. Calculate (measure). On the other hand, for the correction value update process Pc, the processing unit 3 maintains the first measurement range R and causes the measurement unit 2 to newly output the correction value Dc in the first measurement range R, so that this new correction is performed. While performing mainly the correction value update process Pc for updating the correction value Dc used in the first measurement range R stored in the storage unit 4 with the value Dc, the measurement unit 2 is provided with a plurality of types of measurement ranges. The correction value Dc is output in a second measurement range R other than the first measurement range R out of R (in this example, three measurement ranges Ra, Rb, Rc) (that is, the measurement unit 2 performs the first measurement). By temporarily switching the range R to the second measurement range R and temporarily switching to the reference voltage Vr corresponding to the second measurement range R, the correction value Dc in the second measurement range R is output. ), The new correction value Dc Also it executes the correction value updating process Pc for updating the correction value Dc stored in the part 4 used in the second measurement range R.

  That is, the correction value update process Pc that is mainly executed in the first measurement range R is referred to as a first correction value update process Pc, and the correction value update process Pc that is temporarily switched to the second measurement range R is executed. When the second correction value update process Pc is set, the processing unit 3 executes the second correction value update process Pc between the execution of the first correction value update process Pc and the measurement process Pm in the first measurement range R. To do.

  Next, the relationship between the correction value Dc for each measurement range R that is updated and stored in the storage unit 4 in each correction value update process Pc, the measurement value Dm, and the voltage value Vm will be described.

  In the measuring apparatus 1, the operational amplifier 13a constituting the range amplifier 13 has an offset voltage Vos1, and the preamplifier 14 has an offset voltage Vos2. Each of the offset voltages Vos1 and Vos2, and the gain G1 of the range amplifier 13 and the gain G2 of the preamplifier 14 vary according to changes in the measurement environment in which the measurement apparatus 1 is arranged. For this reason, in the measurement apparatus 1, the processing unit 3 uses the correction value Dc used in the measurement range R in which the measurement value Dm is measured, as the measurement value Dm output from the measurement unit 2 in the measurement process Pm. By correcting, the voltage value Vm of the measurement voltage Vin is calculated in a state not affected by the offset voltages Vos1 and Vos2 and the gains G1 and G2 that fluctuate according to changes in the measurement environment (a state in which the influence is excluded). .

Specifically, in the measurement range Ra (the gain G1 of the range amplifier 13 is G1a), when only the switch SW1 of the first switch unit 12 is controlled to be in the ON state, the preamplifier 14 changes to the A / D conversion unit 15. The output second amplified voltage V3 (the second amplified voltage V3 at this time is V3ma) is expressed by the following equation (1).
V3ma = {(Vin + Vos1) × G1a + Vos2} × G2 (1)

Further, when only the switch SW5 of the first switch unit 12 is controlled to be in the ON state in the measurement range Ra, the second amplified voltage V3 (at this time) output from the preamplifier 14 to the A / D conversion unit 15 is controlled. In consideration of the fact that the reference voltage Vrz is zero volts, the second amplified voltage V3 is represented by the following formula (2).
V3za = {(Vrz + Vos1) × G1a + Vos2} × G2
= {Vos1 × G1a + Vos2} × G2 (2)

In addition, when only the switch SW2 of the first switch unit 12 is controlled to be in the on state in the measurement range Ra, the second amplified voltage V3 (at this time) output from the preamplifier 14 to the A / D conversion unit 15 is controlled. The second amplification voltage V3 is set to V3ra) is represented by the following formula (3).
V3ra = {(Vra + Vos1) × G1a + Vos2} × G2 (3)

In this case, if the above formulas (1) to (3) are substituted into the formula of (V3ma−V3za) / (V3ra−V3za) and rearranged,
(V3ma−V3za) / (V3ra−V3za) = Vin / Vra. When this equation is modified, the following equation (4) for the measurement voltage Vin in the measurement range Ra is derived.
Vin = (V3ma−V3za) / (V3ra−V3za) × Vra (4)

  In this equation (4), when the reference voltage Vra is not affected by a change in the measurement environment (constant voltage), the processing unit 3 performs on / off control for the switches SW1 to SW5 of the first switch unit 12. To obtain the voltage data D1 for the two second amplification voltages V3za and V3ra, and use the two voltage data D1 for the correction value Dc (correction values Dcz and Dcr, specifically used in the measurement range Ra). Specifically, it is stored in the storage unit 4 as the correction values Dcza and Dcra (that is, the correction value update process Pc is executed), and it can be considered that the change in the measurement environment can be ignored from the time of acquisition of the correction values Dcza and Dcra. Within a short period of time, on / off control for each of the switches SW1 to SW5 of the first switch unit 12 is executed, and the voltage data about the second amplified voltage V3ma. 1 is obtained as the measurement value Dm (that is, the measurement process Pm is executed), and the obtained measurement value Dm and each of the correction values Dcza and Dcra are expressed by the second amplification voltage V3ma, By substituting V3za and V3ra together with the reference voltage Vra, the measurement voltage Vin (in the state where the influence is eliminated) in the state not affected by the offset voltages Vos1 and Vos2 and the gains G1 and G2 That is, it shows that the voltage value Vm) of the measurement voltage Vin can be calculated.

Further, in the measurement range Rb (the gain G1 of the range amplifier 13 is G1b), the second amplification voltage V3 (the second amplification at this time) when only the switch SW1 of the first switch unit 12 is controlled to be in the ON state. The voltage V3 is set to V3mb) is expressed by the following formula (5).
V3mb = {(Vin + Vos1) × G1b + Vos2} × G2 (5)

In the measurement range Rb, the second amplified voltage V3 when only the switch SW5 of the first switch unit 12 is controlled to be on (the second amplified voltage V3 at this time is V3zb) is a reference. Considering that the voltage Vrz is zero volts, it is expressed by the following formula (6).
V3zb = {(Vrz + Vos1) × G1b + Vos2} × G2
= {Vos1 × G1b + Vos2} × G2 (6)

In the measurement range Rb, the second amplified voltage V3 when only the switch SW3 of the first switch unit 12 is controlled to be on (the second amplified voltage V3 at this time is V3rb) is as follows. It is represented by Formula (7).
V3rb = {(Vrb + Vos1) × G1b + Vos2} × G2 (7)

In this case, when the above formulas (5) to (7) are substituted into the formula of (V3mb−V3zb) / (V3rb−V3zb) and rearranged, the following formula (8) for the measurement voltage Vin in the measurement range Rb is obtained. Derived.
Vin = (V3mb−V3zb) / (V3rb−V3zb) × Vrb (8)

  Accordingly, even in the measurement range Rb, when the reference voltage Vrb is not affected by the change in the measurement environment (constant voltage), the measurement value Dm acquired in the same manner as in the measurement range Ra described above and each By substituting the correction values Dcz and Dcr (specifically, the correction values Dczb and Dcrb) with the reference voltage Vrb as the corresponding second amplification voltages V3mb, V3zb, and V3rb into the above equation (8), each offset voltage Vos1 , Vos2 and the gains G1, G2 are not affected (excluding the influence), and the measurement voltage Vin (that is, the voltage value Vm of the measurement voltage Vin) in the measurement range Rb can be calculated. .

Further, in the measurement range Rc (the gain G1 of the range amplifier 13 is G1c), the second amplification voltage V3 (the second amplification at this time) when only the switch SW1 of the first switch unit 12 is controlled to be in the ON state. The voltage V3 is set to V3mc) is represented by the following formula (9).
V3mc = {(Vin + Vos1) × G1c + Vos2} × G2 (9)

In the measurement range Rc, the second amplified voltage V3 when only the switch SW5 of the first switch unit 12 is controlled to be on (the second amplified voltage V3 at this time is V3zc) is a reference. Considering that the voltage Vrz is zero volts, it is expressed by the following formula (10).
V3zc = {(Vrz + Vos1) × G1c + Vos2} × G2
= {Vos1 × G1c + Vos2} × G2 (10)

In the measurement range Rc, the second amplified voltage V3 when only the switch SW4 of the first switch unit 12 is controlled to be on (the second amplified voltage V3 at this time is V3rc) is as follows. It is represented by Formula (11).
V3rc = {(Vrc + Vos1) × G1c + Vos2} × G2 (11)

In this case, if the above formulas (9) to (11) are substituted into the formula of (V3mc−V3zc) / (V3rc−V3zc) and rearranged, the following formula (12) for the measurement voltage Vin at the measurement range Rc is obtained. Derived.
Vin = (V3mc−V3zc) / (V3rc−V3zc) × Vrc (12)

  Therefore, even in the measurement range Rc, when the reference voltage Vrc is not affected by the change in the measurement environment (constant voltage), the measurement value Dm acquired in the same manner as in the measurement range Ra described above and each By substituting the correction values Dcz, Dcr (specifically, the correction values Dczc, Dcrc) into the above equation (12) as the corresponding second amplified voltages V3mc, V3zc, V3rc together with the reference voltage Vrc, each offset voltage Vos1 , Vos2 and the gains G1 and G2 (in which the influence is excluded), the measurement voltage Vin (that is, the voltage value Vm of the measurement voltage Vin) in the measurement range Rc can be calculated. .

  The storage unit 4 is composed of, for example, a semiconductor memory such as a RAM or a hard disk device, and each of the equations (4), (8), (12), and the measurement voltages Vin corresponding to the measurement ranges Ra to Rc described above. In addition, known voltage values Vra, Vrb, Vrc (assuming the same reference numerals as the corresponding voltages) of the respective reference voltages Vra, Vrb, Vrc are stored. In addition, the storage unit 4 includes individual correction values Rc used in each measurement range R (specifically, correction values Dcza and Dcra used in the measurement range Ra, as described above, used in the measurement range Rb). Correction values Dczb and Dcrb and correction values Dczc and Dcrc) used in the measurement range Rc are updated and stored. The storage unit 4 stores a measured value Dm and a voltage value Vm. In this example, since the voltage value Vrz of the reference voltage Vrz is zero volts, the voltage values Vrz are not stored in the storage unit 4, and the respective expressions for the above V3za, V3zb, and V3zc without the voltage value Vrz are deleted. Although the above equations (4), (8), and (12) are derived using (2), (6), and (10), the voltage value Vrz may be a voltage value other than zero volts. . In this case, the voltage value Vrz is stored in the storage unit 4, and the above equations (4), (8), and (12) are the equations for V3za, V3zb, and V3zc described above including the reference voltage Vrz. Is derived using.

  The output unit 5 includes a display device such as a liquid crystal display as an example, and displays the voltage value Vm of the measurement voltage Vin measured by the processing unit 3 on the screen. Note that the output unit 5 is configured to use an interface circuit that performs data communication with an external device or an interface circuit that can be attached with a removable medium, instead of the display device, and transmits the voltage value Vm to the external device. It can also be stored on removable media.

  Next, the operation of the measuring apparatus 1 will be described with reference to FIG.

  As described above, the processing unit 3 executes the measurement process Pm at the cycle T1 synchronized with the sampling cycle (cycle T2) of the A / D conversion unit 15, and outputs the instantaneous value of the measurement voltage Vin to the measurement unit 2. The voltage data D1 shown is output as the measurement value Dm, and the correction value Dc used in the first measurement range R that has already been selected and the measurement voltage Vin (voltage value Vm) used in the first measurement range R are calculated. An equation for this (any one of the above equations (4), (8), (12)) is read out, and a voltage value Vm is calculated and stored in the storage unit 4.

  At this time, the correction value Dc used in the current first measurement range R is first shifted at a timing shifted by a time corresponding to the period T2 with respect to the period T1 in which the processing unit 3 executes the measurement process Pm. Since the correction value update process Pc is executed in the cycle T1, it is periodically updated to the latest state. For this reason, except for the case where the processing unit 3 calculates the voltage value Vm in the measurement process Pm executed immediately after switching of the measurement range R, in the subsequent measurement process Pm, the measurement value Dm and the latest correction value Dc. Based on the above, the voltage value Vm can be accurately calculated in a state where it is extremely difficult to be affected by changes in the measurement environment.

  Further, the processing unit 3 outputs and displays the calculated voltage value Vm on the output unit 5 and compares it with the current voltage range of the first measurement range R within the period T2 in which the measurement process Pm is executed. Then, when necessary, the range switching process Pr is executed, and a measurement range R other than the current measurement range R selected as the first measurement range R is selected as a new first measurement range R (measurement). The switching control of the measurement range R for the unit 2 is executed).

  Further, as described above, the processing unit 3 replaces the first correction value update process Pc with the second correction value between the execution of the first correction value update process Pc and the measurement process Pm in the first measurement range R. Update processing Pc (processing shown in a state surrounded by a broken-line frame in FIG. 2) is executed. In the second correction value update process Pc, the processing unit 3 causes the measurement unit 2 to output the correction value Dc in the second measurement range R other than the first measurement range R among the plurality of types of measurement ranges R. (That is, by causing the measurement unit 2 to temporarily switch the first measurement range R to the second measurement range R and temporarily switch to the reference voltage Vr corresponding to the second measurement range R, the second The correction value Dc in the measurement range R is output), and the correction value Dc used in the second measurement range R stored in the storage unit 4 is updated with the new correction value Dc. Thereby, in the period during which the measurement process Pm is executed in the first measurement range R, not only the correction value Dc used in the first measurement range R but also the second measurement range R other than the first measurement range R. The correction value Dc used is also updated.

  Specifically, the operation in the first period with the measurement range Rc shown in FIG. 2 as the first measurement range R for the measurement process Pm will be described as an example. In the period T2 in which the measurement process Pm (the measurement process Pm with a hatched line) is executed, it is stored in the first correction value update process Pc (correction value update process Pczc, Pcrc) executed before this measurement process Pm. Corresponding to the correction values Dczc and Dcrc as the latest correction values Dc updated and stored in the unit 4, the measurement values Dm acquired from the measurement unit 2 in the measurement process Pm, and the measurement range Rc stored in the storage unit 4 Based on the voltage value Vrc of the reference voltage Vrc and the calculation formula (12) of the measured voltage Vin (voltage value Vm), the voltage value Vm is calculated and stored in the storage unit 4. Further, the processing unit 3 outputs the calculated (measured) voltage value Vm to the output unit 5 for display during the period T2 in which the measurement process Pm is executed. Thereafter, the processing unit 3 repeatedly executes the measurement process Pm at a cycle T1 in a period in which the measurement range Rc is set as the first measurement range R for the measurement process Pm.

  Further, the processing unit 3 performs the first correction value updating process Pc and the first correction value update process Pc and the first correction value update process Pc in the period T2 (period T2 coming in period T1) located between the periods T2 in which the measurement process Pm is performed. One of the two correction value update processes Pc is executed to update and store the correction values Dc used in all the measurement ranges Ra to Rc stored in the storage unit 4. In the example illustrated in FIG. 2, the processing unit 3, for example, corrects the correction value update process Pczc (the process of updating the correction value Dczc) as the first correction value update process Pc and the correction as the first correction value update process Pc. Value update process Pcrc (process for updating correction value Dcrc), correction value update process Pcza (process for updating correction value Dcza) as second correction value update process Pc, and correction value update as first correction value update process Pc Process Pcc, correction value update process Pcrc as first correction value update process Pc, correction value update process Pcra (process for updating correction value Dcra) as second correction value update process Pc,..., Second correction value Correction value update process Pczb (process for updating correction value Dczb) as update process Pc, correction value update process Pczc as first correction value update process Pc, and first correction value update process P Correction value update processing Pcrc as, correction value update processing Pcrb as second correction value update processing Pc (processing for updating correction value Dcrb), correction value update processing Pczc as first correction value update processing Pc,. Thus, the correction value Dc used in all the measurement ranges Ra to Rc by executing the second correction value update process Pc together with the first correction value update process Pc at a lower frequency than the first correction value update process Pc. Is updated and stored.

  With this configuration, within the period of the period T2 in which the second measurement process Pm hatched in the period in which the measurement range Rc is the first measurement range R for the measurement process Pm, the processing unit 3 As a result of the comparison between the calculated voltage value Vm and the current voltage range of the first measurement range R, it is determined that it is necessary to switch the current measurement range Rc selected as the first measurement range R to another measurement range Rb. When the range switching process Pr is executed, a period in which the measurement range Rb is newly set as the first measurement range R for the measurement process Pm starts.

  Even in the period when the measurement range Rb is the first measurement range R for the measurement process Pm, the processing unit 3 corrects the correction value update process Pczb as the first correction value update process Pc during the first period T2 of this period. In the measurement process Pm executed in the period of the next cycle T2 (process for updating the correction value Dczb), the storage unit 4 in the first correction value update process Pc (correction value update process Pczb) executed immediately before. The correction value Dczb as the latest correction value Dc updated and stored in the first correction value update process Pc (correction) executed in a period in which the immediately previous measurement range Rc is the first measurement range R for the measurement process Pm. Correction value Dcrb as the correction value Dc updated and stored in the storage unit 4 in the value update process Pcrb), the measurement value Dm acquired from the measurement unit 2 in the measurement process Pm, Based on the voltage value Vrb of the reference voltage Vrb corresponding to the measurement range Rb stored in the storage unit 4 and the calculation formula (8) of the measurement voltage Vin (voltage value Vm), the voltage value Vm is calculated and stored. 4 is stored. Further, the processing unit 3 outputs the calculated (measured) voltage value Vm to the output unit 5 for display during the period T2 in which the measurement process Pm is executed.

  Thereafter, the processing unit 3 executes the range switching process Pr as necessary to switch the first measurement range R for the measurement process Pm to any one of the measurement ranges Ra to Rc, while measuring the measurement ranges Ra to Rc. In any period during which Rc is the first measurement range R for the measurement process Pm, the first correction value update process Pc and the second correction value update process Pc are executed together with the measurement process Pm, and the storage unit The correction value Dc used in all the measurement ranges Ra to Rc stored in 4 is updated and stored.

  For this reason, in this measurement apparatus 1, in the measurement process Pm executed immediately after the first measurement range R for the measurement process Pm is switched to the new measurement range R, the processing unit 3 corrects the measurement value Dm. As the correction value Dc for, the correction value Dc that has been updated in the period when the measurement range R immediately before was the first measurement range R for the measurement process Pm, although it may not be the latest, may be used. It is possible. As a result, the processing unit 3 does not update the correction value Dc used in the other measurement ranges R during the period in which the immediately previous measurement range R is the first measurement range R for the measurement process Pm, that is, measurement. The measurement range R selected as the first measurement range R for the process Pm is executed immediately after switching of the measurement range R, as compared with the configuration in which only the correction value Dc used in the measurement range R is updated. In the measurement process Pm, the new correction value Dc can be used. As a result, it is possible to calculate a more accurate voltage value Vm in a state where it is less affected by changes in the measurement environment. In calculating the voltage value Vm, the voltage value Vm can also be calculated by executing a section average (section simple average).

  As described above, according to the measurement apparatus 1, the processing unit 3 performs a plurality of types of measurement on the measurement unit 2 between the execution of the first correction value update process Pc and the measurement process Pm in the first measurement range. Correction in the second measurement range (all measurement ranges R except the measurement range R selected as the first measurement range) other than the first measurement range among the ranges (three measurement ranges Ra to Rc in this example) By executing the second correction value updating process Pc for outputting the value Dc and updating the correction value Dc of the second measurement range stored in the storage unit 4 with the correction value Dc, which measurement range R is Even when selected as the first measurement range, a new correction value Dc can always be used in the measurement process Pm executed immediately after switching of the measurement range R. As a result, the measurement environment changes. Effect more unsusceptible state, it is possible to calculate a more accurate voltage value Vm.

  In addition, all the measurement ranges R except the measurement range R selected as the first measurement range are selected as the first measurement range by causing the measurement unit 2 to output the correction value Dc as the second measurement range. Instead of the above preferred configuration for updating the correction value Dc used in all the measurement ranges R except the measurement range R, the measurement ranges R (measurement ranges adjacent to the measurement range R selected as the first measurement range) When Rb is the currently selected measurement range, the measurement ranges Ra and Rc, and when the measurement range Ra is the currently selected measurement range, in this example, there is only the measurement range Rb. Even in the case of the selected measurement range, only the measurement range Rb) is used as the second measurement range because there is only the measurement range Rb in this example. By outputting the correction value Dc to the measurement section 2 and, it is also possible to use a construction that updates only the correction value Dc to be used in the measurement range R in the neighboring. Also in this configuration, it is possible to update the correction value Dc used in the measurement ranges R that are likely to be selected as the first measurement range next to the measurement range R selected as the first measurement range. As a result, it is possible to increase the possibility that a newer correction value Dc can be used in the measurement process Pm executed immediately after switching the measurement range R selected as the first measurement range to the new measurement range R. It is possible to increase the possibility that a more accurate voltage value Vm can be calculated in a state where the influence of changes in the measurement environment is less likely.

  Further, according to the measurement apparatus 1, the processing unit 3 performs the second correction value update process Pc between the execution of the first correction value update process Pc and the measurement process Pm in the first measurement range. By executing the update process Pc at a frequency lower than that of the update process Pc, the correction value Dc used in the measurement process Pm in the first measurement range (the correction value Dc used in the measurement range R selected as the first measurement range) As a result of increasing the update frequency, the voltage value Vm can be calculated more accurately using the latest correction value Dc.

  Note that the first correction value is used so that the new correction value Dc can be used in the measurement process Pm executed immediately after the measurement range R selected as the first measurement range is switched to the new measurement range R. A configuration in which the frequency of the second correction value update process Pc with respect to the update process Pc is executed higher than in the above example can also be adopted. For example, in the period in which the measurement range Ra shown in FIG. 2 is the first measurement range R, in the above example, the correction value update processing Pcza that is the first correction value update processing Pc and the correction that is the first correction value update processing Pc. A value update process Pcra, a correction value update process Pczb that is a second correction value update process Pc, a correction value update process Pcza that is a first correction value update process Pc, a correction value update process Pcra that is a first correction value update process Pc, Although the second correction value update process Pcb, which is the second correction value update process Pc, is executed at a frequency of the correction value update process Pcrb,..., The correction value update process Pcza, which is the first correction value update process Pc, Pcra, second correction value update processing Pc, correction value update processing Pcb, Pcrb, first correction value update processing Pc, correction value update processing Pcza, Pcra, second correction value update processing Pc A configuration in which the second correction value update processing Pc is executed at a higher frequency such as correction value update processing Pczc, Pcrc,..., Correction value update processing Pcza, Pcra, which is the first correction value update processing Pc, and second correction value. Correction value update processing Pcb, Pcrb as update processing Pc, correction value update processing Pczc, Pcrc as second correction value update processing Pc, correction value update processing Pcza, Pcra as first correction value update processing Pc,. In this way, a configuration in which the second correction value update process Pc is executed at a higher frequency can be employed.

  Further, in order to further improve the accuracy of the voltage value Vm in the measurement process Pm executed in the measurement range R selected as the first measurement range, the second correction value update process Pc with respect to the first correction value update process Pc. It is also possible to adopt a configuration in which the frequency is executed at a lower frequency than in the above example.

  Further, the example in which the number of the measurement ranges R is three has been described, but the number of the measurement ranges R may be plural, and the reference voltage Vr (reference voltage excluding the reference voltage Vrz) suitable for the number of the measurement ranges R and By doing so, it can also be set to two or four or more.

DESCRIPTION OF SYMBOLS 1 Measuring apparatus 2 Measuring part 3 Processing part 4 Memory | storage part Dc correction value Dm Measurement value Pc Correction value update process (1st correction value update process, 2nd correction value update process)
Pm measurement processing R, Ra to Rc Measurement range Vin Measurement voltage Vm Voltage value Vr, Vra, Vrb, Vrc, Vrz Reference voltage

Claims (3)

A storage unit for storing correction values for each measurement range used in the measurement process for the measurement target to be measured in a plurality of types of measurement ranges;
The measurement voltage indicating the measured amount is measured in one measurement range selected from the plurality of types of measurement ranges, and the measurement value is output. The one selected from the plurality of types of measurement ranges A measurement unit that measures a reference voltage in a measurement range and outputs the correction value used in the selected measurement range; and
Selecting one of the plurality of types of measurement ranges as a first measurement range for causing the measurement unit to measure the measurement voltage, causing the measurement unit to output the measurement value, and outputting the correction value; For the output correction value, a first correction value update process is executed to update the correction value of the first measurement range stored in the storage unit with the output correction value. Is a measuring apparatus comprising: a processing unit that executes the measurement process and calculates the measured amount by correcting the measurement value with the correction value of the first measurement range stored in the storage unit There,
The processing unit is other than the first measurement range of the plurality of types of measurement ranges with respect to the measurement unit between the execution of the first correction value update process and the measurement process in the first measurement range. Measurement for executing the second correction value update process for outputting the correction value in the second measurement range and updating the correction value in the second measurement range stored in the storage unit with the output correction value. apparatus.   2. The measurement apparatus according to claim 1, wherein the processing unit executes the second correction value update processing by setting all measurement ranges except the first measurement range among the plurality of types of measurement ranges as the second measurement range.   The measuring apparatus according to claim 1, wherein the processing unit executes the second correction value update process at a lower frequency than the first correction value update process.

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