JP2011179818A - Resistive voltage divider device for calibrating resistance ratio meter and calibration method using the device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that, although a device for use in both a DC bridge and an AC bridge is desired for calibrating a resistance ratio measuring bridge, a conventional device has current dependence and temperature dependence and cannot be precisely calibrated. <P>SOLUTION: The resistive voltage divider device includes at least: a resistor having a nominal value of R/11; and a resistive voltage divider which is obtained by connecting eleven or more unit resistive elements having nominal values of R/11 in series and includes terminals at both ends of each unit resistive element. In some cases, the resistive voltage divider device further includes a resistor having a nominal value of R and a resistor having a nominal value of 1/10 of R, and housed in a metal chassis. This is used to perform the self-calibration and calibration of a resistance ratio meter at high accuracy. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a resistance voltage divider apparatus suitable for highly accurate calibration of a resistance ratio measuring instrument and a calibration method using the apparatus.

  In recent years, precise measurement of electrical resistance values is important in the field of electrical resistance standards, and is also required in other fields. For example, a platinum resistance thermometer is used for precise temperature measurement, but in the field of temperature measurement, precise temperature difference calibration is required, and there is a need to accurately measure minute resistance difference.

  In the field of precision measurement of temperature and electrical resistance, etc., a resistance ratio measuring instrument (also referred to as a resistance ratio measuring bridge or bridge) that measures the ratio of the resistance values of two paired resistors is used. The resistance ratio measurement bridge measures and displays the ratio between the resistance value of the standard resistor and the resistance value of the resistor to be measured. In general, the resistance ratio measurement bridge amplifies and detects and balances the high-order digit circuit that balances the bridge circuit by switching with a relay and the like, and the slight residual signal that cannot be adjusted by the high-order bridge. There is a circuit for the lower digits, and the adjustment and measurement results for the upper and lower digits are finally used as the resistance ratio measurement results. Therefore, in the precise measurement of the resistance ratio, it is important to confirm that the linearity is properly maintained for each of the upper and lower digits.

  Conventionally, the types of bridges are roughly divided into a case where the current flowing through the resistor is a direct current and a case where the current is an alternating current. There are two types of bridges that have been put to practical use so far: one dedicated to direct current and the other dedicated to alternating current.

  The principle of resistance ratio measurement using a dedicated resistance ratio measurement bridge for DC is that current is passed through two resistors to achieve an equilibrium condition in which the voltage drop is equal, and the two current ratios at that time (that is, the reciprocal of the resistance ratio). ) To know. Normally, one current value is fixed at the rated value, and the other current is changed to realize the equilibrium condition. As the bridge output, the current ratio under equilibrium conditions (that is, the reciprocal of the resistance ratio) is displayed and recorded as a measurement result.

  The principle of resistance ratio measurement using an AC-dedicated resistance ratio measurement bridge is to let the same current flow through two resistors and know the two voltage drop ratios (that is, the resistance ratio) at that time. As the bridge output, the voltage drop ratio (that is, the resistance ratio) in the two resistors is displayed and recorded as a measurement result.

  The question of how accurate the ratio displayed here arises in precision measurements. Therefore, as one of the answers to that, “a pair of resistors whose ratios are calibrated in advance (or a pair of voltage drops generated by applying the same current to them)” is input to the bridge, and the display result is correct. Judgment can be made.

  Now, to check the accuracy of the bridge, provide a “pre-ratio calibrated resistance pair” to the bridge as the standard ratio for all resistance ratio values that the bridge can measure. It is difficult. Therefore, as a practical method, a “resistance pair whose ratio has been calibrated in advance” having a nominal resistance ratio obtained by equally dividing the measurement range of the bridge into approximately 10 points has been put to practical use.

  In order to control and indicate the current ratio to be set mainly by manually operating a decimal dial, and to calibrate the indicated value of the bridge current ratio (that is, the reciprocal of the resistance ratio), the maximum digit of “ten” The principle of using a resistance pair group in which a ratio of an integer multiple of one tenth ((10/11) × n, where n = 0, 1, 2,...) ”Is strictly realized is known. The advantage of this principle is that if the integer n is changed from 0 to 10, the arithmetic ideal value of each digit dial takes all integer values from 0 to 9, corresponding to any n. is there. Thereby, the indication values of all digits can be calibrated for all integer values from 0 to 9. Conventionally, a resistance having a nominal ratio of “tenths of tenths ((10/11) × n, where n = 0, 1, 2,...)” Of the maximum digit, realized based on this principle. There is a product that realizes a pair group for an AC bridge. However, in practice, it is impossible to realize a resistance ratio having an arithmetic ideal value that is faithful to the principle. Therefore, it is not always possible to calibrate the indicated value for all integer values from 0 to 9 in the lower digits. There is no limit.

  In addition, for a direct current bridge, there is a conventional technique in which connection of resistors calibrated at a certain rated current is rearranged in series or in parallel in order to realize resistance pairs having various nominal ratios (see Patent Document 1).

  Also, a method of self-calibration of a resistance voltage divider is known (see Non-Patent Document 1 by the present inventor). The resistance voltage divider is used by supplying a rated current (for example, 1 mA) during both self-calibration and comparative calibration. The present inventors have developed a calibration technique for a standard voltage divider in the field of electrical measurement (see Non-Patent Document 1 and Patent Document 2).

Japanese National Patent Publication No. 10-502775 JP 2003-21671 A

T.A. Endo, Y .; Sakamoto et al., “Automated Voltage Divider to Calibration a 10-V Output of Zener Voltage Standard”, IEEE Transaction on Instrumentation and Measurement. 40, No2, pp 333-336 (1991)

  The above-described product for an AC-dedicated bridge uses the principle of an induction voltage divider that can easily realize a relatively accurate voltage dividing ratio in an AC circuit, and is a secondary winding of an excited high permeability core. The number was chosen appropriately. However, those using the principle of the inductive voltage divider have the principle drawback that they cannot be used for calibration of the DC bridge. In addition, in the structure and operation method of the conventional product, the basis for correctly realizing the ratio of ((10/11) × n, where n = 0, 1, 2,...) When the control variable n is changed is , Which is entirely dependent on the principle that “the voltage division ratio of the induction voltage divider is proportional to the number of windings”, and cannot be confirmed experimentally by the self-calibration method. Therefore, there is a problem that it is insufficient from the viewpoint of precision measurement.

  On the other hand, the prior art (see Patent Document 1) determines the nominal value based on the resistance value of the internal resistor, and calibrates the ratio with the external standard resistor in the calibration of the resistance ratio measurement bridge. Therefore, the temperature dependency and current value dependency of the resistance value of the internal resistor greatly affect the calibration result, and the uncertainty is large. That is, every time the nominal ratio is changed, the current value flowing through the resistor is different from that at the time of calibration, so there is uncertainty due to the current dependency of the resistance value. There is a problem that it is not suitable for calibrating a DC bridge with a certain degree of accuracy. Therefore, it is necessary to realize a resistance pair group for resistance ratio measurement so that the current value flowing through the resistance can be kept equal to that at the time of calibration.

  In order to calibrate the resistance ratio measurement bridge, an apparatus that accurately calibrates the linearity of the resistance ratio measurement bridge is desired. It is also desirable to have a structure that allows self-calibration to be completed and maintained within a single unit.

  The necessity of accurately calibrating the linearity of the resistance ratio measuring bridge will be described in detail below. In order to calibrate the linearity, it is important to calibrate the upper digit (global) linearity and the lower digit (local) linearity. The calibration of the upper digit (global) linearity confirms the linearity of the resistance measuring bridge as a whole device. Such linearity calibration is also called evaluation. FIG. 1 is a diagram showing calibration of linearity with the nominal resistance ratio as the horizontal axis and the display value of the resistance measurement bridge to be evaluated as the vertical axis. With respect to the dotted line indicating the ideal linearity, the bridge display value based on the resistance ratio for bridge calibration is shown as a circle. As shown in FIG. 1, calibrating the linearity of the entire apparatus (high-order (global) linearity) corresponds to obtaining a deviation in each nominal ratio. On the other hand, local linearity means that a large number of points are gathered as shown in FIG. 1 by enlarging the circled points for a predetermined nominal resistance ratio. This indicates the local linearity of the displayed value of the resistance measurement bridge to be evaluated. The calibration of the low order (local) linearity is associated with an important issue particularly required in the calibration of temperature difference measurements. In the temperature range of 83K to 962 ° C, the interpolation instrument in the current international temperature scale (ITS-90) is a platinum resistance thermometer. Measure using a highly accurate resistance ratio measurement bridge. In constructing a temperature scale, the discussion of minute temperature differences requires resistance ratio measurement with an uncertainty of about 0.1 ppm, so the linearity of a high-precision resistance ratio measurement bridge, which is a measuring instrument, is about this level Need to be secured. For this reason, it is necessary to realize a voltage divider capable of realizing a stable resistance ratio and to easily confirm the linearity periodically.

  The present invention is intended to solve these problems, and an object thereof is to realize a resistance voltage divider device that can be used for calibration of both a DC bridge and an AC bridge. Another object of the present invention is to realize a resistance voltage divider device that constitutes a resistance pair whose ratio is calibrated in advance before calibration of a DC bridge or an AC bridge. Another object of the present invention is to realize a method for calibrating a resistance ratio measuring device with high accuracy using a resistor voltage divider device.

  In order to achieve the above object, the present invention has the following features.

The apparatus of the present invention is a resistance voltage divider apparatus for calibration of a resistance ratio measuring instrument. The device of the present invention is a resistor (C) having a nominal value of R / 11 and 11 or more unit resistor elements having a nominal value of R / 11 connected in series and having terminals at both ends of each unit resistor element. And a voltage divider (A). The resistive voltage divider according to the present invention is characterized in that 12 or more unit resistive elements having a nominal resistance value of R / 11 are connected in series. Typically, thirteen. The resistor (C) and the resistor voltage divider (A) of the present invention include current terminals at both ends. The device of the present invention preferably further comprises a resistor (B) having a nominal value R. The device of the present invention preferably further comprises a resistor (D) having a nominal value of R / 10. Moreover, you may provide the resistor (B) whose nominal value is R, and the resistor whose nominal value is R / 10. The device of the present invention is characterized by including a resistor (m is 0 or a positive or negative integer) whose nominal value is 10 ^m times R. In addition, a plurality of resistors having a different m and having a nominal value 10 ^m times R (where m is 0 or a positive or negative integer) are provided. Further, the unit resistive element of the resistive voltage divider (A) and the resistor (C) having a nominal value of R / 11 can be manufactured by connecting 11 resistive elements having the same nominal value R in parallel. it can. In general, if an arbitrary natural number is algebraically expressed as i, it can be manufactured by connecting i resistance materials having the same nominal value i × (R / 11) in parallel.

  The method of the present invention is a method for calibrating the resistance ratio measuring capability of a resistance ratio measuring bridge, and is a unit adjacent to the resistor (C) and the resistor voltage divider (A) using a resistor voltage divider device. A resistance ratio with a partial series element made of a resistance element is obtained, and the resistance ratio measurement bridge is calibrated using the resistance ratio. In the method of the present invention, the resistance ratio measurement of the resistance ratio measurement bridge is performed by using the energization current when the resistance ratio between the unit resistance element groups of the resistance voltage divider (A) is self-calibrated and the self-calibration result. It is possible to equalize the energized nominal current when subjected to capacity calibration. The method of the present invention obtains a plurality of different resistance ratios having a small difference around the same nominal ratio by providing redundancy by setting the unit resistive elements of the resistance voltage divider (A) to 12 or more. It is characterized by using a resistance ratio.

  The device of the present invention includes a resistor having a nominal value of R / 11, a resistor voltage divider having terminals connected to both ends of each unit resistor element, in which 11 or more unit resistor elements having a nominal value of R / 11 are connected in series. Therefore, the resistance ratio measurement bridge can be calibrated using “a pair of resistors whose ratios are calibrated in advance”. In addition, since the device of the present invention is based on a new concept of using “a pair of resistances whose ratio when a rated current is passed is calibrated in advance”, it is relatively difficult to calibrate the absolute value of the resistance value. Compared with, uncertainty can be reduced. As described above, since the device of the present invention includes the predetermined resistance voltage divider, it is possible to perform self-calibration of the resistance ratio of the resistor pair required by the elements in the device. In particular, it is easy to achieve high accuracy by designing and mounting a change in temperature coefficient and current dependency of the unit resistance elements of each resistor and resistor voltage divider. In addition, since the resistance materials of the same nominal value are connected in parallel, they can be manufactured relatively easily.

  Since the apparatus of the present invention can be calibrated at its rated current for both direct current and alternating current, it can be used for calibration of both a direct current resistance ratio measurement bridge and an alternating current resistance ratio measurement bridge.

  In the device of the present invention, the rated energization current at the time of self-calibration and the rated energization current at the time of use can be made equal, so there is no uncertainty due to the current dependence of the resistance value, so higher accuracy is guaranteed. Is done. In the apparatus of the present invention, since the resistor voltage divider in which unit resistance elements are connected in series has a structure having current terminals at both ends, calibration is performed while keeping the magnitude of the current flowing through all the unit resistor elements equal. Uncertainty in the resistance ratio due to the current dependency of the resistance value of the resistor can be reduced.

  The resistive voltage divider apparatus of the present invention is a partial series element realized by selecting two voltage terminals of the resistive voltage divider and appropriately configuring the resistor (for example, the nominal value is R (multiple of 10) times R). Can be calibrated for all settings from 0 to 9 for each digit of the decimal dial of the resistance ratio measuring instrument by setting the nominal (resistance) ratio to a certain resistor to an integer multiple of 10/11, for example. it can. That is, the calibration by the apparatus of the present invention has an effect that the linearity of the upper digit and the linearity of the lower digit can be calibrated simultaneously. In particular, since a well-known 1/11 arithmetic trick is used to calibrate the upper digits, man-hours can be reduced. Furthermore, in the device of the present invention, when the resistive voltage divider has 12 or more unit resistive elements connected in series, there are a plurality of combinations of circuits having the same nominal value due to the redundancy of the resistive voltage divider circuit. In addition, the low-order linearity calibration becomes more accurate.

  According to the present invention, for example, the reliability of measurement of a minute temperature difference of about 20 microkelvin (2 / 100,000 ° C.), which is required recently in the field of temperature standards, can be confirmed.

The figure for demonstrating the subject of linearity. The figure which shows the resistive voltage divider apparatus of the 1st Embodiment of this invention. The figure which shows the resistor (B) of the resistance voltage divider apparatus of the 1st Embodiment of this invention. The figure which shows the resistor (C) of the resistive voltage divider apparatus of the 1st Embodiment of this invention. The figure which shows the resistance voltage divider (A) of the resistance voltage divider apparatus of the 1st Embodiment of this invention. The figure which shows the resistor (D) of the resistance voltage divider apparatus of the 1st Embodiment of this invention. The figure which shows the linearity calibration method of the resistance ratio measuring device by the resistance voltage divider apparatus of this invention. The figure which shows the connection of the self-calibration procedure 1 of the apparatus of this invention. The figure which shows the connection of the self-calibration procedure 2 of the apparatus of this invention. The figure which shows the automatic measurement of a resistance ratio measuring apparatus using the apparatus of this invention. The figure explaining the resistance ratio which calibrates the linearity of a resistance ratio measuring device using the apparatus of the present invention. The figure explaining the calibration point which calibrates the linearity of a resistance ratio measuring device using the apparatus of the present invention. The figure which shows the example of the linearity calibration by this invention.

  The device of the present invention includes at least one resistor (C) having a nominal value of R / 11 (typically four terminals) and a resistor having a nominal value of R / 11 (also referred to as a unit resistance element). 11 or more resistor dividers (A) connected in series. Furthermore, at least one resistor having a nominal value that is a multiple of R (an integer power of 10) can be provided as appropriate. Here, the integral multiplication is 0 times and positive and negative integer multiples. That is, a resistor (B) whose nominal value is R and a resistor (D) whose nominal value is (10 times R or (1/10) times R) can be appropriately provided. The resistor (B) and the resistor (D) are typically four-terminal resistors. The nominal value refers to a rounded value or an approximate value related to the characteristics of an instrument that serves as a guide for use. The nominal value is used in accordance with the definition of “International Glossary of Basic Terms” in the ISO / IEC guidelines. Hereinafter, embodiments will be described.

(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings. 2 to 6 are diagrams for explaining the resistance voltage divider device according to the present embodiment. FIG. 2 is a resistance voltage divider device (overall view) according to the present embodiment. The resistance voltage divider apparatus of FIG. 2 includes a resistor (B), a resistor (C), a resistor (D), and a resistance voltage divider (A). A plurality of single resistors (B, C, D) are shown in FIGS. 3, 4 and 6, respectively, and a resistive voltage divider (A) is shown in FIG.

As shown in FIG. 3, the resistor (B) is a single resistor having a nominal value R, and includes two current terminals (C1, C2) and two voltage terminals (P1, P2). Prepare.
As shown in FIG. 4, the resistor (C) is a single resistor having a nominal value (R / 11), and includes two current terminals (C1, C2) and two voltage terminals (P1, P2). As the resistor having a nominal value (R / 11), for example, a resistor having 11 resistor materials having a nominal value R (for example, 100Ω) connected in parallel is used. Due to the parallel connection of resistance materials of the same nominal value, it can be manufactured relatively easily. For example, when R is 100Ω, it is 100/11 (approximately 9.09Ω). In addition, for example, a unit resistance element having a nominal value of R of 100Ω and a nominal value of R / 11≈9.09Ω has a resistance material having a nominal value of 4 × (R / 11) ≈36.363Ω (for example, It can be manufactured by connecting four resistance foils in parallel. That is, in general, if an arbitrary natural number is expressed as an algebra, it can be produced by connecting i resistance materials having the same nominal value i × (R / 11) in parallel.

  FIG. 5 shows a resistive voltage divider (A) in which 11 or more resistors having a nominal value (R / 11) are connected in series. A resistor having a nominal value of (R / 11) is called a “unit resistance element” because it can be said to be one unit of the resistance voltage divider (A). As the unit resistance element, for example, an element in which 11 resistance materials having a nominal value R are connected in parallel is used. The unit resistor element has the same configuration as the resistor (C) having a nominal value of (R / 11), and thus the resistor (C) can be said to be a resistor composed of one unit resistor element. . The minimum number of each resistor (unit resistance element) of the resistor voltage divider is 11, and 12 or more are required to increase the accuracy of calibration, typically 13 and 14 It may be the above. 11 or more and 13 or less are appropriate in terms of convenience in use and compactness. The voltage terminal is drawn out from the node connecting the adjacent unit resistance elements of the resistive voltage divider, and the voltage terminal and the current terminal are drawn out from both ends of the resistive voltage divider. When 13 are connected in series, 14 voltage terminals (P0, P1,... P13) and two current terminals (C1, C2) at both ends are provided. The reason why the number of series connection of unit resistance elements (the nominal resistance value is (R / 11)) of the resistor voltage divider is set to be larger is as follows. There is a slight deviation from the nominal value in the resistance value realized in an actual device. Therefore, if redundancy is provided by setting a large number of series-connected unit resistance elements (nominal resistance value (R / 11)) of the resistor voltage divider, the same nominal ratio (n / 11) is subtle. This is because, since different resistance ratios can be realized from the partial series element of the resistor voltage divider, a plurality of experimental values can be verified in the vicinity of the nominal ratio, and therefore, it can be applied to verification of linearity in the vicinity of the nominal ratio.

  As shown in FIG. 6, the resistor (D) is a single resistor having a nominal value of R / 10 and includes two current terminals (C1, C2) and two voltage terminals (P1, P2). With. As the resistor (D), instead of R / 10, a single resistor which is a multiple of 10 (an integer power of 10) R such as 10R can be used. As an example, in the case of a resistor having a nominal value (R / 10), for example, a resistor manufactured by connecting ten resistance materials having a nominal value R (for example, 100Ω) in parallel is used. Due to the parallel connection of resistance materials of the same nominal value, it can be manufactured relatively easily.

  In each of the resistors and resistor dividers shown in FIGS. 2 to 6, each terminal is typically a binding post and is attached to an electrically highly insulating plate (for example, a highly insulating resin plate). .

  In the present embodiment, the resistor voltage divider (A) and the resistors (B, C, D) are stored as a set in one housing box. The housing box is preferably a metal housing and further preferably has a lid. Moreover, it is preferable that the metal housing can draw out two 4-core lead wires with guards. Moreover, it can also be set as the structure which can be removed separately so that a resistance voltage divider (A) and a resistor (B, C, D) can be calibrated separately. Between the resistors (B, C, D) and the resistor voltage divider (A), the accuracy of precision electrical measurement can be kept high during use by making the electrical insulation sufficiently high.

(Calibration method)
A method of using the resistance voltage divider device of this embodiment will be described. The resistance voltage divider device of the present invention is a device for calibrating the linearity of the resistance ratio measurement bridge, and is used for calibrating the dial of the resistance ratio measurement bridge. That is, the resistance voltage divider for resistance ratio measuring instrument calibration according to the present invention is used in the following two stages. The method comprises the steps of self-calibration of the device of the present invention and the step of calibrating the linearity of the resistance ratio measuring bridge using the self-calibrated device of the present invention. For example, a self-calibration stage for calibrating the resistance ratio between the resistor voltage divider (A) and the resistor (B), and a book in which the resistance ratio between the resistor voltage divider (A) and the resistor (B) is self-calibrated. Calibrating the linearity of the resistance ratio measuring bridge using the apparatus of the invention. Self-calibration consists of the following two procedures. The first procedure for self-calibration is to interpose resistors (C) (one R / 11) so that all the unit resistance elements having the nominal value R / 11 of the resistance voltage divider (A) are mutually connected. This is a procedure for calibrating the resistance ratio. The second procedure of self-calibration is a partial series element (nominal resistance value) in which a resistor (B) (R is one) and 11 adjacent unit resistor elements of the resistor voltage divider (A) are connected in series. This is a procedure for calibrating the ratio to R). If the self-calibration consisting of the procedure of repeating these two resistance ratio measurements using the highest-precision resistance ratio measurement bridge is completed, the resistor (B) (one R) and the resistor voltage divider (A) A ratio with the resistance of a partial series element in which an arbitrary number of adjacent unit resistance elements are connected in series can be known, and a resistance ratio calibration result group of these combinations can be obtained. Furthermore, in order to extend the range of the resistance ratio, a resistor (D) having a nominal value 10 times or 1/10 times R can be used instead of the resistor (B). The resistor B and the resistor (D) are collectively referred to as a resistor having a value that is a value (an integer power of 10) times the nominal value R (where an integer means a positive or negative integer). be able to.

(Method to calibrate the linearity of the resistance ratio measurement bridge)
A method of calibrating the linearity of the resistance ratio measurement bridge using the apparatus of the present embodiment will be described with reference to FIG. FIG. 7 is a diagram showing the connection of the resistance ratio measurement bridge (3), the resistors (B) (2), and the resistance voltage divider (A) (1). The resistors (B, C, D) are four-terminal resistors manufactured using highly stable resistance elements. The resistance voltage divider (A) is a resistance voltage divider in which unit resistance elements are connected in series. However, the resistance voltage divider (A) is regarded as a four-terminal resistor by wiring two current terminals and two different voltage terminals. Can do.

In the resistive voltage divider, when the number of unit resistive elements is 13, ₁₄ C ₂ = 14 × 13/2 = 91 types of four-terminal resistors R _{i, j} can be realized. R _{i, j} is a resistance value between the j-th voltage terminal and the i-th voltage terminal, and i, j represents the number of the voltage terminal.

In FIG. 7, the resistance ratio measurement bridge (3) is a resistance ratio measurement bridge to be calibrated, and is calibrated by measuring the nominal resistance ratio R _{i, j} / R. The four-terminal resistor of the resistor (B) in FIG. The resistance voltage divider (A) in FIG. 7 has 91 nominal resistance values R _i, depending on which pair of 14 voltage terminals is connected to the voltage terminal pair of the conductor from the resistance ratio measurement bridge (3) _{. j} can be realized. The actual resistance ratio R _{i, j} / R is calibrated in advance by self-calibration.

Of the two conductors shown in FIG. 7 as “4-wire”, one system has two ports of the resistance ratio measurement bridge (ie, two current terminals and two voltage terminals, for a total of four). Of the external connection terminal and, in some cases, a guard terminal added to form one set), one of the ports (Rs port) and 4 of the resistor (B) (one R) Connect the terminals using the four-terminal method. The other one system connects the other port (Rx port) and the partial series element selected from the resistor voltage divider (A) by the four-terminal method. That is, the two voltage terminals of the conducting wire are connected to voltage terminals (for example, P0, P1,...) Selected from the resistor voltage divider (A) and voltage terminals (for example, P0, P1,... P13). Here, the case where the number of unit resistive elements of the resistive voltage divider is 13 will be described. In the state where the resistor (B) and the resistor voltage divider (A) are connected as shown in FIG. 7, the resistance ratio measurement bridge (3) to be calibrated measures the resistance ratio R _{i, j} / R. The actual values of these resistance ratios R _{i, j} / R (usually slightly separated from n / 11) are known by the self-calibration method. By comparing the indicated value (dial) when these resistance ratios are measured with the resistance ratio measurement bridge (3) and the actual resistance ratio R _{i, j} / R values obtained by self-calibration, It is possible to calibrate the dial of the resistance ratio measurement bridge (3) because it is possible to know what deviation is included in the indicated value (dial) of the resistance ratio measurement bridge (3) and how it should be corrected and used. it can. The resistance ratio R _{i, j} / R to be measured by the resistance ratio measurement bridge (3) to be calibrated can be changed to the nominal value n / _j by appropriately selecting and changing the voltage terminal of the resistance voltage divider (A) to be connected. 11, n can be swung from 0 to 13 in increments of 1. Therefore, according to the known principle described in the background section, the resistance ratio measurement bridge to be calibrated (3) calibrates the indicated values of all the upper digits and the lower most digits for all integer values from 0 to 9. it can.

Note that the four-terminal resistance ratio R _{i, j} / R (91 ways) of the resistor voltage divider (A) and the resistor (B) (one R) is stable because a highly stable resistor is used. It is. Utilizing this fact, if each value of the resistance ratio of the 91 nominal values R _{i, j} / R is previously calibrated by self-calibration, it can be used for calibration of the linearity of the resistance ratio measurement bridge.

(About self-calibration)
The self-calibration procedure will be described with reference to FIGS. FIG. 8 is a diagram showing a connection in the self-calibration procedure 1. In FIG. 8, a resistance ratio measurement bridge (5) is the most accurate resistance ratio measurement bridge for use in self-calibration of the resistance voltage divider (A) (1), and the resistance ratio R _{i, j} / (R / Used for calibration of 11). The four-terminal resistors (C) and (4) in FIG. 8 have a nominal resistance value R / 11. The resistance voltage divider (A) (1) of FIG. 8 has 13 nominal resistance values R _{i, j} (i) depending on which of the 14 voltage terminals is connected to the voltage terminal pair of the conductor from the bridge. = J + 1; j = 0, 1,..., 13) can be realized. FIG. 9 is a diagram showing a connection in the self-calibration procedure 2. In FIG. 9, a resistance ratio measurement bridge (5) is the most accurate resistance ratio measurement bridge for use in self-calibration of the resistance voltage divider (A) (1), and calibrates the resistance ratio R _{i, j} / R. Used for. The four-terminal resistor (B) in FIG. 9 has a nominal resistance value R. The resistor voltage divider (A) (1) has the same nominal resistance value R (i = j + 11; j = 3) depending on which of the 14 voltage terminals is connected to the voltage terminal pair of the conductors from the bridge. 0, 1, 2) can be realized.

In order to determine the nominal value R _{i, j} / R of the resistance ratio, self-calibration is performed by performing measurement according to the following procedure.

(Procedure 1)
Resistor (C) (nominal value R / 11) for all cases of nominal resistance value R / 11 realized with i and j pairs (i = j + 1) for resistor divider (A) The ratio (approximately 1), R _{i, j} / (R / 11), is measured sequentially. For example, as shown in FIG. 8, a resistance ratio measurement bridge (5) with the highest accuracy is prepared, and one of the two ports of the resistance ratio measurement bridge (5) and a resistor (C) (the nominal value is Connect 4 terminals of one resistor (R / 11). The other port is connected to the resistive voltage divider (A) by the four-terminal method. At that time, the voltage terminal pairs of the conductive wires are a pair of terminals P0 and P1, a pair of terminals P1 and P2, a pair of terminals P2 and P3,..., A terminal P12 and a terminal P13. The resistance ratios R _{i, j} / (R / 11) are sequentially measured by connecting like the pair. In this measurement, a constant rated current is applied to the resistor (C), and a constant rated current substantially equal to the rated current is also applied to the resistor voltage divider (A). Here, “substantially equal” means substantially equal, and no matter how much the AC resistance ratio bridge is used, the power source of the resistor C is a separate power source from the resistor voltage divider A. In principle, it cannot be made completely equal, so the expression is almost equal. When a typical DC resistance ratio bridge is used, since the bridge automatically adjusts the ratio of the currents flowing through the two resistors so that it is the reciprocal of the resistance ratio, the ratio of the two resistances is strictly 1. As a result, the two currents are not exactly equal. In any case, since these are nominally 1: 1 resistance ratio calibrations, for example, by replacing the connection of two resistors connected to the resistance ratio measurement bridge, there is a deviation included in the measurement of the resistance ratio measurement bridge. High-precision calibration is relatively easy, as it can be calculated and corrected. When the sequential measurement is completed, the resistance value R _{i, j} (where i = j + 1) of each unit resistance element of the resistance voltage divider (A) and the resistance value of the resistor (C) (nominal value R / 11) You can know all the ratios. It should be noted that the resistance ratio (this nominal value) to the resistor (C) of an arbitrary number n adjacent to each other in the unit resistive elements of the resistance voltage divider (A) (hereinafter referred to as “partial series element”) is connected. The resistance ratio is n (where n = 0, 1, 2,..., 11,...) Can be obtained by calculation.

  A nominal 1: 1 calibration measurement method will be described. In the method using the DC resistance ratio measurement bridge and the method using the AC resistance ratio measurement bridge, as an example of a specific measurement method, the resistance ratio measurement is performed on one unit resistance element of the resistance voltage divider (A) and the resistor (C). There is a method in which two ports provided in the bridge are each connected by a four-terminal method, a value near 1 indicated by the resistance ratio measurement bridge is recorded with high accuracy, and this is repeated. As another specific example of the measurement method, a voltage terminal corresponding between two resistors, that is, one unit resistance element of a resistor voltage divider (A) and a resistor (C) each having a current having the same rated value applied thereto. There is a method in which one is connected with a short-circuit wire and the other is connected with a voltmeter, a minute voltage difference close to 0 V is measured with a voltmeter, and this is repeated.

(Procedure 2)
R _{i, j} / R _, which is a ratio (approximately 1) to the resistor (B) (nominal value R), is sequentially measured for a pair of i and j that is (i = j + 11) of the resistor voltage divider (A). . For example, as shown in FIG. 9, a resistance ratio measurement bridge (5) with the highest accuracy is prepared, and one of the two ports of the resistance ratio measurement bridge (5) and resistors (B) (2) ( One resistor having a nominal value of R) is connected by a four-terminal method. The other port and the resistance voltage divider (A) (1) are connected by a four-terminal method. At this time, the current terminal pair on the resistance voltage divider (A) (1) side of the conducting wire is connected to the current terminal pair of the resistance voltage divider (A) (1) as usual, but the voltage terminal pair is connected to the terminal P0. The connection is repeated as a pair of terminals P11, a pair of terminals P1 and P12, and a pair of terminals P2 and P13. Then, the ratio R _{i, j} / R of the partial series element, which is a four-terminal resistor, realized by the plurality of connections to the resistor (B) (nominal value R) is sequentially measured. In this measurement, when attention is paid to the n = 11 partial series elements (consisting of series connection of 11 adjacent unit resistance elements) of the resistance voltage divider (A), the nominal resistance value is R. Is a calibration of the resistance ratio of the device according to the embodiment of the present invention with a resistor (B) whose nominal value is R. Since this is a nominal 1: 1 calibration, highly accurate calibration is relatively easy.

From these measurement results, the measured values of the nominal values R _{i, j} / R of all combinations of i and j (where i> j) are obtained by calculation. That is, by using the calculation result of the ratio between the unit resistance elements in the resistance voltage divider (A) in step 1, each resistor in the resistance voltage divider (A) and the resistor (B) whose nominal value is R The resistance ratio of an arbitrary number n of adjacent unit resistors connected in series (the nominal resistance value is (R / 11) × n) is obtained by calculation. In addition, the resistance ratio between the resistor (B) and the resistor (C) can also be obtained by calculation using the three-stage theory.

  After the calibration in steps 1 and 2, the resistor (B) and the partial series element of the resistor voltage divider (A) having various resistance values (the nominal resistance value is (R / 11) × n) Since the ratio is determined, using these in pairs, the nominal ratio is (n / 11, where n = 0, 1, 2,..., 11,. A resistance pair has been provided. The resistance ratio measurement bridge can be calibrated using the resistance pair.

  In the self-calibration of the above procedure and the linearity calibration of the resistance ratio bridge, as shown in FIG. 10, the resistance ratio measurement bridge can be automatically measured by combining with a computer-controlled low thermal electromotive force scanner.

(Example of self-calibration of this device and linearity calibration of bridge)
For self-calibration, the nominal value R is 100Ω. As in Procedure 1 above, the resistance ratio of each unit resistance element (nominal resistance value 100 / 11Ω) of the resistor voltage divider (A) to the resistor (C) (nominal resistance value 100 / 11Ω) (nominal 100/11: 100/11 = 1: 1) is calibrated. Next, as in procedure 2 above, between the 0th terminal and the 11th terminal of the resistance voltage divider (A), between the 1st terminal and the 12th terminal, and between the 2nd terminal and the 13th terminal (nominal resistance value 1100 / 11Ω (= 100Ω)) and the resistance ratio of resistor (B) (nominal resistance value 100Ω) (or resistor (D) (nominal value is 1/10 of R and 10Ω)) is calibrated. Further, if the resistance value of any resistor is calibrated using a resistance standard, all the unit resistance elements of the resistor voltage divider (A) and the resistance values of other resistors are also calibrated.

  Next, the linearity of the bridge is calibrated using the self-calibrated resistance ratio. In the middle column of Fig. 11, "Resistance value between terminal 0 / Ω" is an example of the nominal resistance value (unit is Ω) between each terminal number and terminal 0, rounded to two decimal places It shows. Nominal resistance value between the 1st terminal and the 0th terminal (unit is Ω) is 100/11 = 9.09 Nominal resistance value between the 2nd terminal and the 0th terminal (unit is Ω) is 200/11 = 18.18. The right column “ratio to 10Ω” in FIG. 11 shows the nominal resistance value (unit: Ω) between the terminal of each terminal number of the resistance voltage divider (A) and the 0th terminal, and the resistor (D) (nominal The resistance ratio is 10 ohms) rounded to 9 digits after the decimal point. If all the parameters shown in the left column are assigned from 0 to 9, each dial (digit) will show all values from 0 to 9. It shows that it shows. For example, when looking at the second digit below the decimal point and looking at the right column from the 0th row of the top row to the 10th row, the value is 0, 0, 1, 2, 3, 4, 5, It can be seen that all integers from 0 to 9 appear as 6, 7, 8, and 9. Therefore, for a nominal resistance ratio (n / 11, where n = 0, 1, 2,..., 11,...), A resistance pair whose actual resistance ratio is self-calibrated is provided. , The linearity of the bridge can be calibrated for the full range of each dial (digit) (ie all integers from 0 to 9).

  FIG. 12 uses the coordinate axes of a graph that is normally used to view the measurement results when the resistance ratio measurement bridge is used, and shows the axis of the ratio value indicated by the resistance ratio measurement bridge. The measurement value axis is taken vertically. And, when the nominal resistance ratio (n / 11, where n = 0, 1, 2,..., 11,...), That is, the resistance ratio measurement bridge is calibrated by this method on this coordinate, it is ideal. The points that will be measured as typical calibration results are plotted and displayed as dots, indicating that the vertical (ie, equal to horizontal) coordinates of each dot are shifted from the integer value. Thus, if calibration is performed at all the calibration points shown here, all the instructable values (0, 1, 2,..., 9) are set for all the dials of the resistance ratio measurement bridge. Linearity calibration can be performed.

  The above embodiment is an example in which a resistance ratio measurement bridge is calibrated by using a resistor voltage divider (A) and a resistor (D) that have undergone self-calibration of the necessary resistance ratio. In step 2, a resistor (D) may be used instead of the resistor (B). In a linearity calibration using a resistor (D) (nominal value multiplied by (an integer power of 10)), the resistance ratio between resistor (D) and resistor (B) (nominal value R) (eg, The nominal ratio 1:10) takes advantage of the fact that it can be calibrated relatively easily with high accuracy. In addition to the self-calibrated resistance pair obtained by the self-calibration of the above embodiment, when the resistor (D) is added, the nominal value of the resistor (D) is (1/10 times R). Using the unit resistor element group of the resistor (D) and the resistor voltage divider (A), the nominal ratio is ((10/11) × n, where n = 0, 1, 2,..., 11,. ..) resistance pairs are also provided. By using this, it is possible to perform calibration with a wide calibration range of the resistance ratio measurement bridge.

FIG. 13 shows an implementation in which the linearity of the resistance ratio measurement bridge, which is the original purpose, is calibrated after knowing the value by calibrating the resistance ratio R _{i, j} / R using the apparatus of the present embodiment. An example is shown. In the graph of FIG. 13, the horizontal axis represents the nominal value of the resistance ratio (nominal input resistance ratio in calibration) that was input when the resistance ratio measurement bridge was calibrated by the method of the present invention, and the vertical axis represents the calibration. As a result, the deviation of the indication value of the resistance ratio bridge to be calibrated (development of bridge reading from the reference ratio value) is taken on an enlarged scale. Then, the results of repeated measurements on the nominal resistance ratio (n / 11, where n = 1, 2,..., 12) are plotted on the coordinates.

(Second Embodiment)
The second embodiment has the same structure as that of the first embodiment except that the resistor (D) shown in the first embodiment is not provided. That is, the resistance voltage divider device of the second embodiment includes a resistor (B), a resistor (C), and a resistance voltage divider (A). As in the first embodiment, self-calibration is performed using the resistance voltage divider apparatus of the present embodiment, and the linearity calibration of the resistance ratio measurement bridge is performed using the self-calibrated apparatus of the present invention. .

(Third embodiment)
The third embodiment has the same structure as that of the first embodiment except that the resistor (B) shown in the first embodiment is not provided. The third embodiment is basically the same as the first embodiment in matters that are not particularly described. That is, the resistance voltage divider device according to the third embodiment includes a resistor (C), a resistor (D), and a resistance voltage divider (A). The resistor (C) is one resistor having a nominal value (R / 11) as shown in FIG. 4, and the resistor (D) has a nominal value of R / R as shown in FIG. One resistor which is 10 times the R (10 to the power of an integer). As shown in FIG. 5, the resistance voltage divider (A) is a resistance voltage divider in which 11 or more unit resistance elements having a nominal value (R / 11) are connected in series.

As in the first embodiment, self-calibration is performed using the resistance voltage divider device of the present embodiment, and the linearity of the resistance ratio measurement bridge is calibrated using the self-calibrated device.
First, in this embodiment, instead of using the resistor (B) in the first embodiment, i and j that become (i = j + 11) of the resistance voltage divider (A) in the procedure 2 of the self-calibration. R _{i, j} / (R (multiple of 10)), which is a ratio of the resistor (D) (the nominal value is (multiple of 10)) of R, is sequentially measured.

  Next, the linearity of the resistance ratio measurement bridge is calibrated using the self-calibrated apparatus of the present embodiment. In the wiring diagram of FIG. 7, measurement is performed using the resistance ratio between the resistor (D) and the partial series element of the resistor voltage divider (A) connected to the resistor (D) instead of the resistor (B). Calibrate the bridge.

(Fourth embodiment)
The fourth embodiment has the same structure as that of the first embodiment except that the resistor B and the resistor D shown in the first embodiment are not provided. The device may be a separate unit without the resistor B and the resistor D, and even if a separate unit having a nominal value equal to the resistor B or the resistor D described above is used, it is the same in another form. An effect is obtained.
Further, if the self-calibration is performed in the form of the resistor voltage divider (A) and the resistor (C) without providing the resistor B and the resistor D and preparing an equivalent separate product, the nominal n , N = 1, 2,..., 11,..., The resistance ratio measurement bridge can be calibrated with high accuracy. In this case, since the “trick obtained by dividing decimal number by 11” is not used, it is not necessarily expected to change the nominal display value of each digit after the decimal point over all integers from 0 to 9. Linearity calibration can be performed, and by providing redundancy to the number of unit resistive elements of the resistive voltage divider (A), the nominal values of these global calibrations (n, n = 1, 2,...). , 11,...) Local linearity calibration around can also be performed.

(Fifth embodiment)
In addition to the combination of resistors shown in the above embodiments, other nominal value resistors can be used. For example, a resistor voltage divider (A), a resistor (C), and a plurality of resistors having a different m and a nominal value of 10 ^m times R (where m is 0 or a positive or negative integer). A resistive voltage divider device. In this embodiment, the ratio of the resistor with the nominal value R is calibrated, and a resistor whose nominal value is one hundred times or one hundredth can be further combined, and these resistors are prepared. By selecting as appropriate, flexible calibration can be realized by changing the calibration range of the resistance ratio measuring instrument.

(Sixth embodiment)
The temperature dependency of the resistance value of the resistor constituting the resistance voltage divider device of the present invention should be as small as possible. However, a resistor that can be actually manufactured always has temperature dependency. In this embodiment, a configuration for reducing temperature dependence is provided. The temperature coefficient of each resistor in the vicinity of the operating temperature of the resistor voltage divider device is made uniform. It is desirable to devise the following mounting methods for the resistor voltage divider (A) and the resistors (B, C, D). Then, by reducing the temperature dependence, the resistance ratio R _{i, j} / R and the like can be maintained with an uncertainty smaller than the uncertainty of the resistance value of each resistance element. For example, it is preferable to reduce the temperature coefficient of the resistance elements constituting each resistor and the resistor voltage divider. In addition, the accuracy of the resistance ratio can be improved by aligning the temperature coefficient (the relative amount of the partial differentiation of the resistance value with respect to the resistance value) to substantially the same value. By configuring each resistance element with the same material, the temperature coefficients can be made uniform. Further, the effect of temperature change can be eliminated by keeping the resistor and the resistor voltage divider in a single housing and keeping them isothermal. Thus, by making the temperature dependence of each resistor uniform, the temperature dependence of the resistance value ratio (resistance vs.) obtained in self-calibration can be made smaller than the temperature dependence of the resistance value itself. .

  The above embodiments can be used in appropriate combination, and the examples shown in the above embodiments and the like are described for easy understanding of the invention, and are not limited to these embodiments.

  In the industry, it is required to calibrate a resistance ratio measurement bridge used in fields such as precision measurement of temperature and electric resistance with high accuracy, and therefore it is useful to apply the present invention.

Claims (14)

A resistance voltage divider device for calibration of a resistance ratio measuring instrument,
A resistor having a nominal value of R / 11;
11 or more unit resistor elements having a nominal value R / 11 connected in series, and a resistor voltage divider having terminals at both ends of each unit resistor element;
A resistance voltage divider device comprising:   2. The resistance voltage divider apparatus according to claim 1, wherein the resistance voltage divider has 12 or more unit resistance elements connected in series.   3. The resistor voltage divider apparatus according to claim 1, wherein the resistor and the resistor voltage divider include current terminals at both ends.   The resistor voltage divider device according to claim 1, further comprising a resistor having a nominal value of R. 5.   5. The resistance voltage divider device according to claim 1, further comprising a resistor having a nominal value of R / 10. The resistance voltage divider apparatus according to claim 1, further comprising a resistor having a nominal value 10 ^m times R (where m is 0 or a positive or negative integer). 4. The apparatus according to claim 1, further comprising a plurality of resistors having different values of m and having a nominal value of 10 ^m times R (where m is 0 or a positive or negative integer). 5. The resistive voltage divider device described.   2. The resistive voltage divider apparatus according to claim 1, wherein the unit resistive element of the resistive voltage divider is formed by connecting 11 resistive elements having a nominal value R in parallel.   2. The resistance voltage divider apparatus according to claim 1, wherein the resistor having a nominal value of R / 11 comprises 11 resistor elements having a nominal value of R connected in parallel.   2. The unit resistive element of the resistive voltage divider is formed by connecting an i number of resistance materials having a nominal value i × (R / 11) in parallel with an algebraic representation of an arbitrary natural number as i. Resistance voltage divider device.   The resistor having a nominal value of R / 11 comprises an arbitrary algebraic notation of i as an algebraic expression, and i resistor materials having a nominal value i × (R / 11) connected in parallel. The resistance voltage divider apparatus according to claim 1. A method for calibrating a resistance ratio measuring instrument,
A resistor voltage divider comprising at least a resistor having a nominal value of R / 11 and a resistor voltage divider having at least 11 unit resistor elements having a nominal value of R / 11 connected in series and having terminals at both ends of each unit resistor element Using the device,
A calibration method characterized by obtaining a resistance ratio between the resistor and a partial series element composed of adjacent unit resistor elements of the resistor voltage divider, and calibrating the resistance ratio measuring instrument using the resistance ratio.   13. The calibration method according to claim 12, wherein the energization current at the time of self-calibration is equal to the energization current at the time of use.   It is characterized in that a plurality of different resistance ratios having a minute difference around the same nominal ratio are obtained by using 12 or more unit resistance elements of the resistance voltage divider to provide redundancy, and the resistance ratio is used. The calibration method according to claim 12.