JPH0349072B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resistance deviation characteristic tester for measuring the deviation characteristics of a resistance element before manufacturing a variable resistor.

As shown in FIG. 1, a DC power supply 12 is connected between both ends of the variable resistor 11, and the voltage obtained when the movable element 13 of the variable resistor 11 is slid onto its resistance element 14 is, for example, linear. something is required. Before incorporating the resistance element 14 as the variable resistor 11, the linearity of only the resistance element itself is tested. For example, the first
In the figure, before making a variable resistor, a predetermined voltage is applied to both end faces of the resistance element 14, and a plurality of probes 15 are brought into contact with the resistance element 14 at equal intervals, and the probes 15 are Plot each voltage as shown in Figure 2, and create a resistance characteristic line 1 connecting the plots.
Make 6. Furthermore, the voltage value Vs ₁ at a predetermined reference point Ps of the ideal resistance characteristic line, that is, the predetermined linearly changing ideal characteristic line 17, and the reference point Ps on the actual resistance characteristic line 16. Find the deviation ΔV from the above value Vx, and draw a line 18 that passes through the value Vx on the actual characteristic line at the reference point Ps and is parallel to the ideal characteristic line 17.
, it is inspected to see how much deviation each point of the actual resistance characteristic line 16 has, for example, whether it is within a predetermined area (shaded area), and whether it is within that area. If it is a good product, it is used to incorporate it into a variable resistor.

Conventionally, when performing such a linearity test, the third
As shown in the figure, probes 1 1 to 1n are brought into contact with the resistive element 14 to be measured at regular intervals along its extension direction, and these probes _{1 1 to} 1n are connected to input terminals 2 ₁ to 2n of the multiplexer 21, respectively. . On the other hand, a reference resistance element 22 is provided for the resistance element 14 to be measured, and probes _{3 1 to} 3 n are similarly contacted in the same number and at the same intervals. ₁ to 4n, respectively. A voltage is applied to both ends of the resistance element 14 to be measured and the reference low resistance element 22 from the DC power supply 12.
Vs is applied. The probe 1s that contacts the reference point Ps of the resistive element 14 to be measured is connected to the input terminal 2s of the multiplexer 21. A probe 3s that contacts the reference point Ps of the reference resistance element 22 is connected to an input terminal 4s of the multiplexer 23.

In the multiplexers 21 and 23, corresponding ones of the input terminals 2 ₁ to 2n and 4 ₁ to 4n are sequentially selected by the control unit 24, and the input voltages thereof are taken out and output. These outputs are differential amplifier 2
5. On the other hand, voltages corresponding to the reference point Ps are also applied to the differential amplifier 26 from the terminals 2s and 4s, and the difference voltages are taken out. In other words, the voltage difference ΔV at the reference point Ps in FIG. 2 is obtained from the differential amplifier 26. As the output of the differential amplifier 25, the difference voltages at the corresponding measurement points of each probe are sequentially obtained. Therefore, the voltage difference between each plot point of the actual resistance characteristic line 16 and each corresponding point of the ideal line 17 in FIG. It is taken by.

The output of the differential amplifier 27 is the deviation between the plot point of the resistance characteristic line 16 and the corresponding point of the reference line 18 in FIG. The output of this differential amplifier 27 is
It is converted into a digital signal by the AD converter 28 and supplied to the display 29. For example, the position on the reference line 18 on the horizontal axis corresponds to the measurement point of each probe, and the deviation between the reference lines is the characteristic line 16 and 18. Such a deviation characteristic line 31 is recorded and displayed.

By looking at this deviation characteristic line 31, it can be immediately determined whether the resistance element to be measured is a good product or not, and a resistance deviation characteristic test can be performed. However, the tester shown in FIG. 3 is not generally available on the market, and it was necessary to create a tester specifically for this purpose. Differential amplifiers 25, 2 in the configuration in FIG.
6, that is, multiplexers 21 and 2
3. Control unit 24, differential amplifier 27, AD converter 2
8. The portion 32 including the display section 29 is generally commercially available as a data logger. However, this commercially available product cannot be used directly as a conventional resistance deviation characteristic tester, and it is actually difficult to insert the differential amplifiers 25 and 26 in Fig. 3 into a commercially available data acquisition device. It was hot. For this reason, conventional resistance deviation characteristic testers have had to be expensive.

From this point of view, as shown in FIG.
A DC power source 12' is separately provided for the probe 1s for the reference point Ps of the resistive element 14 to be measured.
The voltage obtained at and the reference point of the reference resistance element 22
It is conceivable that the difference between the voltage obtained at the probe 3s of Ps and the voltage obtained by the probe 3s of Ps is obtained by the differential amplifier 33 to obtain a differential voltage ΔV, and this differential voltage is applied to the reference potential point of the power supply 12 with respect to the resistance element 14 to be measured. .

In this way, the differential amplifier 25 calculates the difference between the voltage obtained by applying the probes 1 ₁ to 1n to the multiplexer 21 and the voltage obtained by the multiplexer 23 from the voltage obtained to the probes 3 ₁ to 3n. , the output of the differential amplifier 25 is directly AD
If the signal is converted into a digital signal by the converter 28 and displayed on the display 29, the same display as that on the display 29 in FIG. 3 can be obtained. According to this configuration, a commercially available conventional data recorder 32 can be used, and the overall configuration can be made at low cost.

However, in this case, the power supply 12 is a floating power supply that is not grounded, so the power supply voltage becomes unstable, and a power transformer, a power filter, etc. are also required as the power supply 12'. If the power supply is unstable, accurate measurements will not be obtained.

An object of the present invention is to provide a resistance deviation characteristic tester which can use a commercially available data recorder as is and which can perform stable and accurate measurements.

According to this invention, the voltage at the reference point of the resistance element to be measured and the voltage at the reference point of the corresponding reference resistance element are input to an operational amplifier, and the deviation thereof is extracted.
This deviation and the DC voltage to be applied to both ends of the resistive element to be measured are added by an adder circuit, and both ends of the resistive element to be measured are connected between the output side of the adder circuit and the output side of the operational amplifier. In this way, negative feedback is applied to eliminate the deviation between the two inputs of the operational amplifier, and a voltage subtracted by the difference in potential between the reference points is applied to the resisted element.

FIG. 5 shows an example of a resistance deviation characteristic tester according to the present invention, and parts corresponding to those in FIG. 4 are designated by the same reference numerals. In this invention, the reference voltage generation circuit 3
4 is provided. The reference voltage generation circuit 34 generates a voltage Vs to be applied across the resistance element 14 to be measured;
The voltage obtained at the reference point of the reference resistance element is generated. In this example, the reference resistance element 2
2 is provided, a power supply 12' is connected to both end faces thereof, one end of the power supply 12' is grounded, and a voltage Vs is applied to the reference resistance element 22. A probe 3s is brought into contact with a reference point Ps of this reference resistance element 22, and a reference voltage is obtained from this probe 3s.
If the type of resistance element to be measured is determined, the applied voltage Vs is determined, and the reference point is also determined. A reference voltage generation circuit 34 may be provided that generates only the corresponding voltage.

Probe 1 at reference point Ps of resistive element 14 to be measured
The voltage obtained at s and the reference point of the reference resistance element 22
The voltage obtained at the probe 3s of Ps is applied to the inverting input side and the non-inverting input side of the operational amplifier 35, respectively. The output of the operational amplifier 35 and the voltage to be applied to the resistive element 14 from the reference voltage generating circuit 34, that is, the voltage Vs of the power supply 12' in this example, are added in an adding circuit 36. The output side of this adder circuit 36 and the output side of the operational amplifier 35 are connected to the resistor element 1.
Connected to both ends of 4.

Because of this configuration, the resistor element 1 is connected between the output side and the inverting input side of the operational amplifier 35.
4 and its reference point Ps is connected as a feedback resistor so that there is no potential difference at each reference point on both input sides of the operational amplifier 35, that is, in the resistive elements 14 and 22. The potential of the reference point of the resistance element 14 is the same as that of the reference resistance element 22.
Negative feedback is applied to the output side of the operational amplifier 35 so that the potential is equal to the potential of the reference point of FIGS. 1 and 2.
The deviation ΔV shown in the figure is obtained.

This ΔV and the voltage Vs of the power supply 12' are added by an adder circuit, and this added value is applied to the other end of the resistance element 14 to be measured. Therefore, Vs is applied to both end faces of the resistive element 14 to be measured, and the reference potential point of the resistive element 14 is shifted by ΔV, so that each point of the resistive element 14 and Probes 1 ₁ to 1n in contact and probes 3 ₁ to 3n in contact with corresponding points on the reference resistance element
The multiplexers 21 and 23 take out the corresponding voltages obtained respectively, the output is deducted by the differential amplifier 25, converted into a digital signal by the AD converter 28, and displayed on the display 29.
The same display line 31 in FIG. 3 is obtained.

In other words, as in the case of FIG. 4, a commercially available data recorder 32 can be used as is. Moreover, in this case, the float power supply 12 in FIG.
In addition, an operational amplifier 35 and an adder circuit 36 are used, but these can be inexpensive commercially available products and can be easily assembled. . Therefore, compared to the one shown in Fig. 3, it is possible to make a device that is much cheaper overall, and compared to the one shown in Fig. 4, it operates more stably and can therefore perform measurements with high precision. It is possible to do this, and it is also a composition.

Generally, some data recorders 32 have a built-in judgment means that judges the deviation to be a failure when the deviation is a predetermined value or more, and the judgment to pass if the deviation is less than a predetermined value. It is also possible to display only the pass/fail of the resistance element to be measured, with those within the value being considered as passes. Also multiplexer 21
Only the output of is supplied to the display 37 (if necessary
AD conversion, etc.) may be displayed as a display line 38 that corresponds to the characteristic line 16 in FIG. 2 and is obtained by subtracting ΔV. In this case, the probes ₃₁ to 3n of the reference resistance element 22 are not required, and it is only necessary to generate the voltage of the probe 3s of the reference point Ps from the reference voltage generation circuit 34 and output only this and Vs. As mentioned above, if the type of resistance element to be measured is determined, the voltage of the probe 3s is
It is determined in advance and can be generated without providing the reference resistance element 22.

[Brief explanation of drawings]

Figure 1 is a diagram showing a variable resistor for explaining resistance deviation characteristics, Figure 2 is a diagram showing the relationship between the resistance deviation characteristic line and the reference line, and Figure 3 is a diagram showing a conventional resistance deviation characteristic tester. 4 is a block diagram showing an improved resistance deviation characteristic tester, and FIG. 5 is a block diagram showing a resistance deviation characteristic tester according to the present invention. 1 ₁ to 1n, 3 ₁ to 3n: probe, 14:
Resistance element to be measured, 22: Reference resistance element, 21, 2
3: Multiplexer, 25: Differential amplifier, 28:
AD converter, 29, 37: display, 32: data recorder, 35: operational amplifier, 36: addition circuit.

Claims (1)

[Claims] 1. A plurality of probes that are brought into contact with predetermined measurement points of a resistance element to be measured, and a reference voltage and a reference voltage at a predetermined reference point on an ideal resistance characteristic line of the resistance element to be measured. A reference voltage generation circuit that generates a voltage to be applied between both ends of the resistive element to be measured, and a voltage of a probe in contact with a measurement point on the resistive element to be measured that corresponds to the reference voltage and the reference point are input. an operational amplifier, an adder circuit that adds the output of the operational amplifier and the voltage across the voltage from the reference voltage generation circuit, and the device under test between the output side of the adder circuit and the output side of the operational amplifier. The first connecting the resistive element,
A resistance deviation characteristic tester comprising a second connection terminal and a data acquisition device from which voltages from the probe are sequentially acquired.