JP2814166B2 - Measuring instrument - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring instrument for measuring various physical quantities or supplying various physical quantities for measurement, such as a digital multimeter of an electronic measuring instrument.

[0002]

2. Description of the Related Art Measuring instruments measure various physical quantities,
It supplies various physical quantities for measurement, and is used in various fields.

[0003] By the way, very few measurers work while paying attention to the reliability of the measured value displayed by the measuring instrument. In other words, measurement is rarely performed while considering the inherent error of the measuring instrument.In many cases, the measured value displayed by the measuring instrument is read as it is, and it is believed that it is the correct value. We use as.

[0004] In particular, in the case where the display value is stable in a digital measuring instrument or the like, it is easy to read the data, and it is liable to treat all data including the least significant display digit as correct data. Whenever a measurer performs a measurement, it is rarely performed to calculate and confirm the reliability of the displayed value by looking at the specifications in the instruction manual of the measuring instrument to be used.

[0005]

Even if a physical quantity is measured or supplied in such a state, the displayed value may contain a large error depending on the selection of the range of use and function of the measuring instrument. There is a problem that the unreliable value is treated as a true value.

[0006] Nowadays, many instruments having excellent resolution, which is the minimum change amount indicating how finely a measuring instrument can measure or supply a physical quantity, have been able to be digitally displayed.

[0007] However, even if a number of display digits of such a digital measuring instrument are arranged, it is not possible to rely on the numerical values of all the digits. In short, the displayed value of the measuring instrument is surprisingly unreliable. If it is inadvertently arranged, meaningless digits are arranged as data, and an invalid value enters a part.

In order to avoid such a situation, “how much is the accuracy under the current measurement conditions”, “how reliable is the displayed value”, and “how many digits are valid and necessary values” It is necessary to know by all means.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and allows a measurer to be informed of the accuracy of a measuring instrument at the time of measurement, and a tolerance indicating the reliability of a displayed value. It is an object of the present invention to provide a highly reliable measuring instrument capable of indicating a range.

[0010]

A first measuring instrument according to the present invention comprises: storage means for storing data of a plurality of types of inherent errors of the measuring instrument corresponding to the type of physical quantity and the measuring range; Error data selecting means for reading error data from the error data storage means, accuracy calculation means for calculating accuracy based on the read error data and actually measured values, and display means for displaying the calculated accuracy. It is characterized by having.

The second measuring instrument according to the present invention comprises a storage means for storing data of a plurality of types of inherent errors of the measuring instrument according to the type of physical quantity and the measuring range; Error data selecting means for reading error data from storage means, accuracy calculating means for calculating accuracy based on the read error data and actually measured values, and a tolerance obtained in the process of calculating the accuracy, and It is characterized by comprising a tolerance range calculating means for calculating a tolerance range for the measured value based on the measured value, and a display means for displaying the calculated accuracy and the tolerance range.

In the first or second measuring device, a physical quantity is supplied to the measuring device for measurement, and the supplied value is stored in the error data storage means in the same manner as the measured value. May be stored, the accuracy or the tolerance range may be calculated by the calculation means, and the calculation result may be displayed.

[0013]

The error data selecting means reads the corresponding error data from the error data storage means in accordance with the type of the physical quantity and the setting conditions of the range of the measured quantity and the supply quantity. The accuracy calculating means calculates the accuracy based on the read error data and the actual measured value / supplied value. Further, the tolerance range calculating means calculates the tolerance range based on the tolerance obtained in the accuracy calculation process and the measured value / supply value. The accuracy and the tolerance range are displayed on the display means, and the operator can be notified of the accuracy and the tolerance range (lower limit value, upper limit value) of the measured value / supply value at that time through the display.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the measuring instrument according to the present invention will be described below in detail with reference to the drawings. The present invention is applied to a measuring instrument for measuring an arbitrary physical quantity and a measuring instrument for supplying an arbitrary physical quantity required for the measurement to the measuring instrument.

FIG. 1 is a block diagram showing the electrical configuration of the measuring instrument according to the embodiment. The measurement condition setting means 10 includes a function 11 for selecting the type of the physical quantity and a range 12 for switching according to the magnitude of the measurement quantity, and outputs a measurement condition setting signal 10a according to an arbitrary combination thereof. Has become. Error data storage means 20
Is stored in advance with various inherent errors regarding various physical quantities and measurement ranges, that is, error data such as a reading error 21, a full-scale error 22, a digit error 23, a calibration cycle error 24, and a temperature characteristic error 25. is there. The error data selection means 30 accesses the error data storage means 20 based on the input measurement condition setting signal 10a, reads out the error data 20a corresponding to the measurement condition setting signal 10a, and outputs the value A to the accuracy calculation means 50. Is to be sent. The measurement data 40 is data of a result measured by the measuring instrument in accordance with the measurement condition indicated by the measurement condition setting signal 10a, and the value B of the measurement data 40 is sent to the accuracy calculation means 50.

The accuracy calculation means 50 first obtains a tolerance C based on the error data value A and the measurement data value B, and calculates the accuracy D of the measuring instrument from the tolerance C and the measurement data value B, The signal of the accuracy D is sent to the display means 70. The tolerance range calculating means 60 calculates a tolerance range E based on the measured data value B and the tolerance C calculated on the way in the accuracy calculating means 50, and displays a signal of the tolerance range E on the display means 70. Send out.

The display means 70 displays the measured data value B and the accuracy D
And the tolerance range E are displayed to notify the measurer.

In the above description of the embodiments,
Although the measuring instrument used for measurement has been described, the accuracy of the physical quantity to be output and the output quantity are stable by providing the same function as above for the measuring instrument that supplies the physical quantity necessary for measurement to the measuring instrument. Thus, a tolerance range indicating that there is reliability can be displayed, and a measuring instrument as a highly reliable physical quantity output device can be configured.

Hereinafter, a digital multimeter (DMM) for measuring electric quantities such as voltage and current will be described as an example of a measuring instrument that performs the above operation. As shown in FIG. 2, the digital multimeter 100 includes a push-button function key 81 on its front panel 80 for selecting a plurality of functions 11 such as DC voltage, AC voltage, DC current, AC current, resistance, and temperature. A range adjustment key 82 comprising an up / down key for adjusting a plurality of ranges 12 for switching according to the measurement range;
, A measurement value display section 83 for displaying the accuracy D and the tolerance range E
And accuracy • tolerance range lower limit display section 84 for displaying by switching between the upper limit value E _1, and a tolerance range upper limit display section 85 for displaying the lower limit E ₂ tolerance range E.

Various methods are conceivable for obtaining a measurement condition setting signal 10a composed of a combination of the function 11 and the range 12 in the measurement condition setting means 10. For example, as shown in FIG. 3, the measurement condition setting signal 10a is obtained by turning on / off an interlocking switch SW _i (i = 1, 2,...) That outputs signals corresponding to the function key 81 and the range adjustment key 82. Can be Assume that one interlocking switch corresponds to one key, and automatically generates an 8-bit measurement condition setting signal 10a in which the upper 4 bits correspond to the function 11 and the lower 4 bits correspond to the range 12, and an error is generated. The data is sent to the data selection means 30. When the number of functions 11 and the number of ranges 12 are large, a 16-bit signal is used as the measurement condition setting signal 10a.

The error data selection means 30 accesses the error data storage means 20 based on the measurement condition setting signal 10a input from the measurement condition setting means 10, and selects the error data 20a corresponding to the measurement condition setting signal 10a. The error data value A is read out and sent to the accuracy calculating means 50.

Here, the format of the error data 20a in the error data storage means 20 will be described with reference to FIG. In FIG. 4, the upper rdg in each cell is shown.
Indicates a reading error 21 (reading), and f. s is a full-scale error 22 (full scal
e) is shown. For example, assuming that the error data 20a is “00010100” corresponding to FIG. 3, the upper four bits “0001” representing the function 11 specify the DC voltage (DCV), and the lower four bits representing the range 12. Since “0100” designates the 20V range, in this case, as the error data 20a, the reading error 21 is ± 0.01% and the full-scale error 22 is ± 0.0%.
The error data of 1% is selected and read.

For other error data 20a, such as the calibration cycle error 24 and the temperature characteristic error 25, a data file similar to FIG. 4 is created corresponding to each cycle and temperature, and as shown in FIG. A new setting signal is generated by a simple switch configuration, and is used as a measurement condition setting signal obtained by adding several bits to the 8-bit signal. Then, the error data storage means 20 is accessed by the measurement condition setting signal, and the reading error 21 and the full scale error 22 are read.
In addition, a calibration cycle error 24, a temperature characteristic error 25, and the like are also read. However, here, the calibration cycle error 2
4 and the temperature characteristic error 25 are omitted, and only the reading error 21 and the full-scale error 22 are considered.

Next, the operation of the accuracy calculation means 50 will be described in detail. For the accuracy calculation means 50, the error data selection means 30 sends the error data 20a (± 0.01% o).
frdg), value A of (± 0.01% of f.s)
And the value B of the measurement data 40 as a result of the measurement based on the measurement condition setting signal 10a. The error data value A is indicated as a combination of the reading error 21 for the measurement data 40 in the corresponding range and the full-scale error 22 in the range.

[Example 1] When the error data value A is (0.
01% of rdg), (0.01% of f.
In the case of (s), as an example, the value B of the measurement data 40 for the DC voltage displayed on the measurement value display unit 83 is “20.
000 V ". A reading error 21 of 0.0
1% is equivalent to 0.002 V in voltage value from 20.000 × 0.01 ÷ 100 = 0.002. Also, 0.01% of the full scale error 22 is 20% of the full scale.
Since V = 20.000 V, 20.000 × 0.01 ÷ 100 = 0.002, which corresponds to a voltage value of 0.002 V. Therefore, the value of the tolerance C obtained by summing the reading error 21 and the full-scale error 22 is as follows: C = 0.002 + 0.002 = 0.004... Become. Assuming that the error other than the reading error 21 and the full-scale error 22 is omitted, the accuracy D is calculated from the value of the above-mentioned tolerance C of 0.004 V. From 0.004 × 100 ÷ 20.000 = 0.02, The accuracy D is as follows: D = 0.02% ..................................................................

[Example 2] As another example of the case of the same error data value A as in the above [Example 1], the measured value display section 83
The measurement data 40 of the DC voltage displayed in “1” is “1”.
5.000 V ″. 0.01% of the reading error 21 is equivalent to a voltage value of 0.0015 V from 15.000 × 0.01 ÷ 100 = 0.015. 22 is the same as in [Example 1], and the full scale is 20 V = 20.000 V. Therefore, 20.000 × 0.01 ÷ 100 = 0.002, and the voltage value is 0.1%. Therefore, the value of the tolerance C obtained by combining the reading error 21 and the full-scale error 22 is 0 from C = 0.015 + 0.002 = 0.0035. .0035 V. The value of the tolerance C is 0.0.
The accuracy D is calculated from 035V. From 0.0035 × 100 ÷ 15,000 = 0.023, the accuracy D is: D = 0.023% …………………………………. ………………

The value (or) of the accuracy D calculated as described above is displayed on the accuracy / tolerance range lower limit display section 84.
Will be displayed automatically.

Next, the operation of the tolerance range calculating means 60 will be described in detail. The measurement data value B obtained as a result of the measurement based on the measurement condition setting signal 10a and the tolerance C which is an intermediate result of the calculation in the accuracy calculation means 50 are input to the tolerance range calculation means 60. come. The tolerance range calculating means 60 calculates a tolerance range E based on the measured data value B and the tolerance C.

Since the tolerance C in the case of the above [Example 1] is more 0.004V, the tolerance C is added to ± 0.
The addition of 004V and the measured data value B = 20.000V, tolerance range E is, E = the lower limit E ₂ ~ upper limit E ₁
E = 19.996V-20.004V ………………………………. The tolerance C in the case of [Example 2] is more 0.003.
Since it is 5V, ± 0.0035V and the measured data value B =
By the addition with 15.000V, the tolerance range E is as follows: E = 14.9965V to 15.0035V....

The tolerance range E calculated as described above
Lower limit E ₂ of displayed automatically in accuracy, tolerance range lower limit display section 84, an upper limit value E ₁ is automatically displayed in the tolerance range upper limit display section 85. In the case of [Example 1], the measured data value B = 2 displayed on the measured value display unit 83
The true value for 0.000V is 19.996V-20.
In the case of [Example 2], it means that the true value for the measured data value B = 15,000 V exists between 14.9965 V to 15.0035 V. doing.

The error data storage means 20, the error data selection means 30, the accuracy calculation means 50 and the tolerance range calculation means 60 are specifically realized by a microcomputer, and the display means 70 (each of the display sections 84 and 85). ), The measurer can be notified of the accuracy D and the tolerance range E. The measurer who sees these displays can clearly know the accuracy of the measuring instrument (digital multimeter) and the tolerance range of the measured value and the supply value.

In the above embodiment, one measuring instrument (digital multimeter) is provided with the accuracy calculation means 50 and the tolerance range calculation means 60, and the display means 70 displays the accuracy D and the tolerance range E. Although both are configured to be displayed, depending on the measuring instrument, the accuracy calculation means 50 may be provided but the tolerance range calculation means 60 may be omitted, or the tolerance range calculation means 60 may be provided. The accuracy calculation means 50 may be omitted. Further, the present invention is applied not only to a measuring instrument used only for measuring a physical quantity but also to a measuring instrument (for example, a power supply) configured to supply a physical quantity to the measuring instrument for measurement in the same manner as in the above embodiment. May be applied. That is, for the supply value, data of a plurality of types of inherent errors of the measuring device corresponding to the type of the physical quantity and the measurement range are stored, the accuracy or the tolerance range is calculated by the calculating means, and the result is displayed. Is also good.

As described above, the measurer can easily judge which digit is valid rather than relying on the measured value / supplied value as in the conventional case. Become.

[0034] Recently, the necessity of calibration of measuring instruments has been required by the ISO standard or the like. However, a measuring instrument capable of instantaneously displaying the accuracy or tolerance range with respect to the standard signal input from the standard instrument in calibration. Therefore, the calibration work becomes very convenient and the work time can be shortened.
Anyone can easily check the performance of the measuring instrument using the standard signal in daily inspection.

[0035]

As described above, according to the present invention, the accuracy of the measuring instrument according to the type of the physical quantity and the measuring range and the tolerance range of the measured value and the supply value are calculated and displayed instantaneously. You can let them know. Since the operator can easily judge which digit is valid, rather than overestimating the displayed measured value / supplied value to the lowest value as a true value, treat it as highly reliable data. Will be able to

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of a measuring instrument according to one embodiment of the present invention.

FIG. 2 is a front view showing the appearance of the digital multimeter according to the embodiment.

FIG. 3 is a diagram illustrating a specific example of a measurement condition setting unit in the digital multimeter according to the embodiment.

FIG. 4 is a format of an error specification data file in the digital multimeter according to the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Measurement condition setting means 10a Measurement condition setting signal 20 Error data storage means 20a Error data 21 Reading error 22 Full scale error 30 Error data selection means 40 Measurement data 50 Accuracy calculation means 60 Tolerance range calculation means 70 Display means 81 Function key 82 Range adjustment key 83 Measurement value display 84 Accuracy / tolerance range lower limit display 85 Tolerance range upper limit display 100 Digital multimeter A Error data value B Measurement data value C Tolerance D Accuracy E Tolerance range E ₁ Tolerance the upper limit of the difference range E ₂ tolerance range lower limit

Claims (3)

(57) [Claims] 1. A storage means for storing a plurality of types of inherent error data of a measuring instrument corresponding to a type of a physical quantity and a measurement range, and an error data selection means for reading error data from the error data storage means in accordance with a setting condition. A measuring device comprising: a calculation unit configured to calculate the accuracy based on the read error data and the actually measured value; and a display unit configured to display the calculated accuracy. 2. A storage means for storing data of a plurality of types of inherent errors of a measuring instrument corresponding to a type of a physical quantity and a measurement range, and an error data selecting means for reading error data from the error data storage means in accordance with a setting condition. And accuracy calculation means for calculating the accuracy based on the read error data and the actually measured value, and the tolerance for the measured value based on the tolerance obtained in the process of calculating the accuracy and the measured value. A measuring instrument comprising: a tolerance range calculating means for calculating a difference range; and a display means for displaying the calculated accuracy and the tolerance range. 3. The measuring device according to claim 1, wherein a physical quantity is supplied to the measuring device for measurement, and the supplied value is the same as the measured value. A measuring instrument characterized by storing data of an inherent error, calculating an accuracy or a tolerance range by a calculation means, and displaying the calculation result.