JP2008139224A - Measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measuring apparatus which can both easily read a measurement value and quickly switch to a measurement range suitable for magnitude of the measurement value. <P>SOLUTION: The measuring apparatus includes a measuring unit 3 for measuring a resistance value R of an object 100 to be measured in a predetermined measurement range switched from a plurality of measurement ranges and a CPU 8 for controlling the switchover of the measurement range. The CPU 8 carries out the range switchover for switching to another measurement range when a state of change of the resistance value R measured in the predetermined range satisfies predetermined conditions and in addition the resistance value R is out of a measurement scope in the predetermined measurement range. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a measurement apparatus that measures parameters of a measurement object in a predetermined measurement range switched from a plurality of measurement ranges.

As this type of measuring apparatus, a measuring apparatus disclosed by the applicant in Japanese Patent Laid-Open No. 2001-41982 is known. In this measurement device, when a measurement target signal is input, the control circuit identifies all measurement ranges in which the peak value of the measurement target signal falls within the measurement range from a plurality of measurement ranges (input ranges). The first process is temporarily determined, and all the measurement ranges suitable for the magnitude of the effective value of the signal to be measured are specified and the second process is temporarily determined. In addition, the control circuit determines a measurement range most suitable for measurement from the measurement ranges temporarily determined by the first process and the second process according to a predetermined determination procedure, and switches to the measurement range. For this reason, in this measuring apparatus, since it is possible to directly switch to the measurement range most suitable for the magnitude of the measurement value (peak value and effective value), compared with the method of switching the measurement range one by one in descending order or ascending order. The measurement range can be switched in a short time.
JP 2001-41982 (page 4-5, Fig. 1-2)

  However, the measurement apparatus has the following problems to be improved. That is, in this measuring apparatus, for example, when the peak value fluctuates instantaneously due to the influence of disturbance, the measurement range is immediately switched along with the fluctuation. For this reason, when the influence of disturbance is large and the peak value frequently moves up and down, the measurement range may be frequently switched. In this case, generally, the display unit (for example, “mV”, “V”, “kV” in the case of measuring voltage) when displaying the measured value is switched in conjunction with the measurement range. Therefore, in this measurement device, there is a possibility that reading of measured values may be difficult due to frequent switching of the display unit in conjunction with the measurement range in a measurement environment where the influence of disturbance is large. Is desired.

  The present invention has been made in view of the problems to be improved, and provides a measuring device that can achieve both readability of a measurement value and switching to a measurement range suitable for the size of the measurement value in a short time. The main purpose is to provide.

  In order to achieve the above object, the measurement apparatus according to claim 1 controls a measurement unit that measures a parameter of a measurement object in a predetermined measurement range switched from among a plurality of measurement ranges, and controls switching of the measurement ranges. A control unit that performs the measurement, the change state of the measurement value measured in the predetermined measurement range satisfies a predetermined condition, and the measurement value is in the predetermined measurement range A range switching process for switching to another measurement range when the measurement range is out of is performed. The “measurement range” in the present invention refers to a range defined for each measurement range as a range in which the measurement unit can accurately measure the parameter.

  The measuring apparatus according to claim 2 is the measuring apparatus according to claim 1, wherein the control unit sets the predetermined condition when a difference value between two measured values measured in succession is within a predetermined range. Suppose you satisfy.

  According to the measurement apparatus of claim 1, when the control unit executes the range switching process and the change state of the measurement value satisfies a predetermined condition and the measurement value is out of the measurement range in the measurement range, another measurement is performed. By switching to the range, for example, when the measured value fluctuates greatly due to the influence of disturbance, the measured range is kept constant regardless of the magnitude of the measured value, and when the change in measured value becomes small, the measured value becomes Instantly and automatically switch to a suitable measurement range. For this reason, even if the measurement value fluctuates frequently, a situation in which the measurement range and the display range are frequently switched can be reliably avoided. Therefore, according to this measuring apparatus, it is possible to achieve both the readability of the measurement value and the switching to the measurement range suitable for the magnitude of the measurement value in a short time.

  According to the measuring apparatus of claim 2, the control unit satisfies the predetermined condition when the difference value between the two measured values measured in succession is within a predetermined range. Since it is easy to calculate the difference value of the measured value and to determine whether the calculated difference value is within a predetermined range, it is easy to determine whether to perform range switching even when the measured value changes drastically. It can be done reliably in time.

  Hereinafter, the best mode of a measuring apparatus according to the present invention will be described with reference to the accompanying drawings.

  First, the configuration of the resistance measuring apparatus 1 will be described with reference to the attached drawings.

  1 and 3 is an example of a measuring apparatus according to the present invention, and is configured to be able to measure the resistance of the measuring object 100 (an example of a parameter in the present invention) by a four-terminal method. . Moreover, the resistance measuring apparatus 1 has an auto range function for automatically switching to a measurement range suitable for the level (size) of a measurement value from a plurality of measurement ranges. Specifically, as shown in FIG. 1, the resistance measurement apparatus 1 includes a power supply unit 2, a measurement unit 3, a ROM 4, a RAM 5, an operation unit 6, a display unit 7, and a CPU 8.

  The power supply unit 2 is configured to be able to generate a measurement current Im for measurement. In this case, the power supply unit 2 is connected to the first terminals 11a and 11b (see FIG. 1), and the measurement current Im is connected to the pair of connected parts 101 in the measurement object 100 via the first terminals 11a and 11b. Is output.

  As shown in FIG. 2, the measurement unit 3 includes an operational amplifier 21, resistors 22, 23, a resistance switching circuit 24, and an A / D conversion circuit 25. The operational amplifier 21 detects, through the second terminals 12a and 12b (see FIG. 1) and the resistor 22, the voltage generated when the measurement current Im is output to the connected portion 101 of the measurement object 100 under the control of the CPU 8. Then, the detection signal Sd is output. The first terminal 11a and the second terminal 12a described above are disposed in a state of being insulated from each other at the tip of the probe unit 9a shown in FIG. 3, and the first terminal 11b and the second terminal 12b described above The probe unit 9b shown in the figure is disposed in a state of being insulated from each other.

  The resistor 22 has a function of detecting the voltage generated between the two connected portions 101, 101 of the measuring object 100 and determining the gain of the operational amplifier 21 in combination with the resistor 23. In addition, a plurality of (in this example, five) resistors 23, 23,... Are range switching resistors having different resistance values, and one of these is a negative feedback path of the operational amplifier 21 by the resistor switching circuit 24. Connected to. The resistance switching circuit 24 switches and connects one of the resistors 23, 23... To the negative feedback path under the control of the CPU 8. The A / D conversion circuit 25 generates voltage data Dv by performing analog-digital conversion on the detection signal Sd output from the operational amplifier 21 and outputs the voltage data Dv to the CPU 8.

  The ROM 4 stores a threshold value Ds used for determining whether or not to perform range switching in the range switching process 40 (see FIG. 5) executed by the CPU 8. In this case, the ROM 4 stores in advance a plurality of threshold values Ds defined for each measurement range. The RAM 5 stores a resistance value R calculated by the CPU 8.

  As shown in FIG. 3, the operation unit 6 includes various switches such as a power switch 31 and a measurement start switch 32 disposed on the front surface of the resistance measuring device 1, and operates corresponding to the operation of each switch. The signal So is output to the CPU 8. As shown in FIG. 4, the display unit 7 includes a display panel disposed in front of the resistance measuring device 1, and as shown in FIG. 4, the measured value (resistance value R) is controlled under the control of the CPU 8. Is displayed.

  The CPU 8 corresponds to the control unit in the present invention, and controls the power supply unit 2 and the measurement unit 3 according to the operation signal So output from the operation unit 6. In addition, when the operation signal So corresponding to the measurement start switch 32 is output from the operation unit 6, the CPU 8 executes resistance value measurement processing. In this case, the CPU 8 executes the range switching process 40 when executing the resistance value measurement process.

  Next, a method for measuring the resistance value R of the measuring object 100 using the resistance measuring device 1 and the operation of the resistance measuring device 1 at that time will be described with reference to the drawings.

  First, the power switch 31 of the operation unit 6 is operated. At this time, the CPU 8 initializes the RAM 5 and erases each data stored in the RAM 5. Next, the measurement start switch 32 of the operation unit 6 is operated. At this time, the operation unit 6 outputs an operation signal So corresponding to the measurement start switch 32, and the CPU 8 executes resistance value measurement processing according to the operation signal So. In this resistance value measurement process, the CPU 8 first controls the resistance switching circuit 24 of the measurement unit 3 to connect the resistor 23 having the smallest resistance value among the resistors 23, 23... To the negative feedback path. As a result, the measurement range is initialized (switched) to the measurement range with the maximum upper limit value. Further, the CPU 8 controls the power supply unit 2 to generate the measurement current Im.

  Subsequently, the first terminals 11 a and 11 b and the second terminals 12 a and 12 b are respectively pressed against the connected portion 101 of the measuring object 100 by pressing the probe units 9 a and 9 b against the connected portion 101 of the measuring object 100. Make contact. At this time, the measurement current Im is output to the connected portion 101 of the measuring object 100 via the first terminals 11 a and 11 b, and thereby the voltage generated between the connected portions 101 and 101 is converted to the operational amplifier 21 of the measuring portion 3. Is detected via the second terminals 12a and 12b and the resistor 22, and a detection signal Sd is output.

  Next, the A / D conversion circuit 25 outputs voltage data Dv generated by analog-digital conversion of the detection signal Sd. Subsequently, the CPU 8 calculates a resistance value R of the measurement object 100 based on the voltage data Dv. Next, the CPU 8 stores the resistance value R in the RAM 5 (hereinafter, the resistance value R stored in the RAM 5 is also referred to as “resistance value Rm”), and generates display data Di for displaying the resistance value R. And output to the display unit 7. Thereby, as shown in FIG. 4, the resistance value R is displayed on the display unit 7. In this case, the CPU 8 generates display data Di so that the resistance value R is displayed in a display unit (for example, “MΩ”) corresponding to the initially set measurement range.

  Subsequently, when a predetermined time (measurement sampling cycle) has elapsed from the calculation time point (first calculation time point) of the above-described resistance value R, the CPU 8 creates a new resistance based on the voltage data Dv output at that time point. While calculating the value R, the range switching process 40 shown in FIG. 5 is performed. In this range switching process 40, the CPU 8 reads from the ROM 4 a threshold value Ds corresponding to the initially set measurement range (the measurement range having the largest upper limit value) (step 41). Next, the CPU 8 reads the resistance value Rm from the RAM 5 (step 42).

  Subsequently, the CPU 8 calculates a difference value Rd between the calculated new resistance value R and the read resistance value Rm (step 43), and the absolute value of the difference value Rd is within the threshold value Ds (predetermined in the present invention). It is determined whether it is within the range (step 44). At this time, when the absolute value of the difference value Rd is not within the threshold value Ds, that is, when the resistance value Rm varies greatly, the CPU 8 sets the measurement range set at that time regardless of the magnitude of the resistance value R. The range switching process 40 is terminated while maintaining the state set to (initially set measurement range in this case).

  Here, when the cause of the fluctuation of the resistance value R is due to the influence of disturbance, even if the new resistance value R momentarily exceeds the upper limit value of the measurement range set at that time, generally, Immediately falls within the measurement range. In this case, in the conventional measuring apparatus that switches the measurement range according to the magnitude of the resistance value R regardless of the magnitude of the fluctuation of the resistance value R, the measurement range is changed whenever the resistance value R changes. Accordingly, the display unit may be changed in conjunction with this, and it may be difficult to read the resistance value R. On the other hand, in the resistance measuring apparatus 1, when the resistance value R varies greatly as described above, the resistance value R is maintained regardless of the magnitude of the resistance value R, so that it is difficult to read the resistance value R. This is surely prevented.

  Next, the CPU 8 overwrites and stores the new resistance value R in the RAM 5 and outputs display data Di for displaying the resistance value R to the display unit 7. The display unit 7 displays the display data Di. The resistance value R is displayed based on Di. Subsequently, when a predetermined time has elapsed, the CPU 8 calculates a new resistance value R based on the voltage data Dv output at that time, and executes the range switching process 40 shown in FIG.

  In this case, when the absolute value of the difference value Rd is within the threshold value Ds in the above-described step 44 (“when the change state of the measured value satisfies a predetermined condition” in the present invention), the CPU 8 It is determined whether or not the new resistance value R deviates from the measurement range in the measurement range set at that time (the range in which the measurement unit 3 can accurately measure the resistance value R) (step 45). At this time, when the new resistance value R is within the measurement range of the measurement range (not out of the measurement range), the CPU 8 maintains the state set to the measurement range. On the other hand, when the new resistance value R is out of the measurement range of the measurement range, the CPU 8 controls the resistance switching circuit 24 of the measurement unit 3 to perform measurement associated with the magnitude of the resistance value R in advance. The measurement range is switched to another measurement range by connecting the resistance 23 for the range (the other measurement range in the present invention) to the negative feedback path (step 46).

  Next, the CPU 8 overwrites and stores the new resistance value R in the RAM 5, and outputs display data Di for displaying the resistance value R to the display unit 7. In this case, the CPU 8 generates display data Di so that the resistance value R is displayed in a display unit (for example, “kΩ”) corresponding to the measurement range after switching. Thereby, as shown in FIG. 6, the resistance value R is displayed on the display unit 7. Thereafter, the CPU 8 executes the above-described processes every time a predetermined time elapses.

  As described above, according to the resistance measuring apparatus 1, when the CPU 8 executes the range switching process 40, the change state of the resistance value R satisfies a predetermined condition, and the resistance value R is out of the measurement range of the measurement range. In addition, by switching to another measurement range suitable for the measurement of the measurement value R, for example, when the resistance value R varies greatly due to the influence of a disturbance, the measurement range is kept constant regardless of the magnitude of the resistance value R. When the change of the resistance value R becomes small, it can be automatically switched to the measurement range suitable for the resistance value R immediately. For this reason, even if the resistance value R frequently fluctuates, it is possible to reliably avoid a situation in which the measurement range and the display range are frequently switched accordingly. Therefore, according to the resistance measuring apparatus 1, it is possible to achieve both the readability of the resistance value R and the switching to the measurement range suitable for the magnitude of the resistance value R in a short time.

  Moreover, according to this resistance measuring apparatus 1, CPU8 discriminate | determines that predetermined conditions were satisfy | filled when the absolute value of the difference value Rd of the two resistance values R measured continuously is less than threshold value Ds. Thus, it is easy to calculate the difference value Rd and determine whether or not the absolute value of the difference value Rd is within the threshold value Ds, so whether or not the range is switched even in a state where the resistance value R changes drastically. Such a determination can be made in a short time and reliably.

  In addition, this invention is not limited to said structure. For example, the example applied to the resistance measuring apparatus 1 that measures the resistance value R as a parameter in the present invention has been described above, but has an automatic measurement range switching (auto-range switching) function, such as current, voltage, power, and temperature. The present invention can be applied to various measuring devices such as an ammeter, a voltmeter, a wattmeter, a multimeter, and a waveform recording device capable of measuring various parameters. In addition, although the example in which the CPU 8 determines that the predetermined condition is satisfied when the absolute value of the difference value Rd between the two resistance values R measured continuously is within the threshold value Ds has been described above, A configuration for determining whether or not a predetermined condition is satisfied may be employed. Specifically, a difference value between the measured resistance value R and the average value of a plurality of resistance values R measured before the measurement of the resistance value R is calculated, and the absolute value of the difference value is a threshold value. It is also possible to adopt a configuration that determines that a predetermined condition is satisfied when it is within Ds. It is also possible to employ a configuration in which the rate of change of two consecutive resistance values R is calculated and it is determined that a predetermined condition is satisfied when the rate of change is equal to or less than the rate of change defined as a threshold value.

1 is a block diagram showing a configuration of a resistance measuring device 1. FIG. 3 is a circuit diagram illustrating a circuit configuration of a measurement unit 3. FIG. 1 is a front view of a resistance measuring device 1. FIG. It is a display screen figure in the state where resistance value R is displayed on display part 7. 5 is a flowchart of a range switching process 40. It is a display screen figure in the state where resistance value R is displayed on display part 7 after change of a measurement range.

Explanation of symbols

1 Resistance Measuring Device 2 Measuring Unit 8 CPU
40 Range switching processing 100 Measurement object Ds Threshold value R Resistance value Rd Difference value Rm Resistance value

Claims (2)

A measurement device comprising a measurement unit that measures a parameter for a measurement object in a predetermined measurement range switched from among a plurality of measurement ranges, and a control unit that controls switching of the measurement range,
The control unit performs the other measurement when the change state of the measurement value measured in the predetermined measurement range satisfies a predetermined condition and the measurement value is out of the measurement range in the predetermined measurement range. A measuring device that performs range switching processing for switching to a range.   The measurement apparatus according to claim 1, wherein the control unit satisfies the predetermined condition when a difference value between the two measurement values continuously measured is within a predetermined range.

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