JPH07151611A - Method for adjusting display of physical quantity measuring instrument - Google Patents

Abstract

PURPOSE:To provide a display adjusting method which is not affected by the contact resistance of a contact pin brought into contact with input terminals for inspection at the time of inspecting and adjusting displayed values of a temperature measuring instrument, etc. CONSTITUTION:In a temperature measuring device in which a sensor, the resistance value of which changes with temperature, is connected between paired input terminals 2A and 2B and which displays the voltage generated between input terminal 2A and 2B when a constant current is made to flow through the sensor after converting the voltage into a digital value by means of an A/D converter, a voltage generator 10 which applies a constant voltage between the terminals 2A and 2B is connected and a voltage measuring instrument 12 which measures the voltage applied between the terminals 2A and 2B is connected between the terminals 2A and 2B at the time of adjusting the variation between measured values and displayed values. In addition, when the instrument 12 measures an appropriate voltage, the digital displayed value is adjusted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus having a physical quantity measuring function, such as a temperature controller, for adjusting a variation in correspondence between a display value of a measurement result and an actual measurement value (physical quantity). The present invention relates to a display adjustment method.

[0002]

2. Description of the Related Art A temperature controller connects a temperature measuring resistance element such as a thermistor between a pair of input terminals, measures the temperature of an object to be measured by the temperature measuring resistance element, and measures the combustion state of the object. The control is performed so as to match the ideal set value. In a device having such a temperature measuring function, the temperature detected by the resistance element is usually displayed digitally.

FIG. 4 is a block diagram showing the principle of temperature measurement of a temperature controller. In the figure, 1 is a temperature controller main body (hereinafter referred to as "product"), 2A and 2B are a pair of input terminals,
Reference numeral 3 is a temperature measuring resistance element connected between the pair of input terminals 2A and 2B (one of the sensing elements whose resistance value changes according to the physical quantity to be measured, and hereinafter referred to as "sensor"). is there. A constant current I is supplied from the constant current source 4 to the sensor 3, and the product 1 side takes in a voltage value V between the input terminals 2A and 2B generated by the resistance value R of the sensor 3. Since the resistance value R of the sensor 3 changes depending on the temperature, it is possible to know the temperature change of the sensor 3 by monitoring the change of the voltage value V = IR between the input terminals 2A and 2B.
The product 1 converts the captured voltage value (analog value) into a digital value by an A / D converter (not shown), and displays temperature data on a digital display (not shown).

By the way, in the case of the product 1, when the characteristics of the individual sensors (thermistors) 3 are the same and the object of the same temperature is measured due to the variation of the individual characteristics of the A / D converter provided therein. However, the temperature display value may be different.

Therefore, in order to provide a product of constant quality, the measured temperature and the display of the product 1 should be matched.
Inspecting and adjusting.

In the conventional inspection / adjustment method, a pseudo resistor having the same resistance value as the resistance value indicated by the sensor at a specific temperature is connected between the input terminals instead of the sensor, and a constant current inside the product is obtained. A constant current was supplied from a source to the pseudo resistance, the voltage was converted to a voltage by Ohm's law V = IR, and the display value was adjusted so that the temperature was displayed according to this voltage value. .

FIG. 5 shows the situation. Contact pins 6A and 6B extending from both ends of the resistance generator 5 are brought into contact with the surfaces of the pair of input terminals 2A and 2B of the product 1, and in this state, the resistance value to be inspected is set in the resistance generator 5, The display value is being adjusted.

When the sensor is actually connected to the input terminal, the sensor is screwed to the input terminal.
When adjusting the contact pin 6 to improve work efficiency
A and 6B are used to electrically connect the resistance generator 5 to the input terminals 2A and 2B.

[0009]

By the way, when the contact pins 6A and 6B are used, it is theoretically unavoidable that contact resistance is generated between the input terminals 2A and 2B and the contact pins 6A and 6B. . Therefore, although the resistance generator 5 gives the set resistance value corresponding to the inspection temperature, the product 1 is actually given the “set resistance value + contact resistance value”. .

FIG. 6 shows a circuit configuration when there is contact resistance. Each contact pin 6A, 6B and input terminal 2A,
The contact resistance values r1 and r2 between 2B are the resistance generator 5
The actual resistance value is added to the set resistance value r3 by
1 + r2 + r3 ”. Therefore, the actual voltage value V
Becomes V = I × (r1 + r2 + r3), and the planned value V =
Since it deviates from I × r3, accurate display adjustment cannot be performed.

When high accuracy is not required, the influence of the above-mentioned variation due to the contact resistance does not cause such a problem, but when the demand for the product accuracy becomes very strict, the influence of the above contact resistance is ignored. I can't. Therefore, a method of increasing the number of contact pins to reduce the contact resistance value was taken, but it was not a fundamental solution.

The present invention has been made to solve the above problems, and provides a display adjustment method of a physical quantity measuring device which can perform appropriate adjustment with little influence of contact resistance. The purpose is to

[0013]

A display adjusting method for a physical quantity measuring device according to the present invention comprises connecting a voltage generator for applying a constant voltage between a pair of input terminals, and connecting the input terminals with each other. A voltage measuring device for measuring a voltage applied between is connected, and when the voltage measuring device measures an appropriate voltage, the contents of the display are adjusted.

[0014]

In the display adjusting method for the physical quantity measuring device according to the present invention, the "inspection resistance value x
The voltage value corresponding to the "constant current value" is given, and the voltage measuring device monitors whether the voltage value applied between the input terminals is appropriate, and the displayed content is adjusted only when it is appropriate. Therefore, even if there is contact resistance, the display value can be adjusted accurately without being affected by the contact resistance.

As a concrete procedure, first, the constant current value of the circuit in the device is measured by connecting an ammeter between the input terminals (it is not necessary to measure if the constant current value is known in advance). ). At this time, there is a contact resistance between the input terminal and the contact pin, but since the constant current circuit always flows a constant current even if the load in the circuit changes, the effect of this resistance can be ignored. it can. Next, the temperature-converted resistance value to be inspected is multiplied by the current value just measured, and the voltage value is obtained according to Ohm's law. And
This voltage value is applied between the voltage generator and the input terminal.
Then, the same voltage value as that tested by using the resistor can be taken into the device without being affected by the contact resistance.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a situation in which the display adjusting method of this embodiment is carried out, and FIG. 2 is a circuit block diagram of the same. In these figures, 1 is a product, 4 is a constant current source, 2A, 2B
Is a pair of input terminals for screwing and connecting a sensor such as a thermistor. These are exactly the same as those shown in FIG. When performing this display adjustment method, the product 1
The voltage value for inspection is obtained from the constant current value of the constant current source 4 inside and the temperature-converted resistance value to be inspected. Next, input terminal 2
A voltage generator 10 that generates a constant voltage is connected between A and 2B, and a voltage measuring device 12 that measures the voltage value applied to the input terminals 2A and 2B is connected.

A plurality of contact pins 16A, 16B, 26A, 26B are used for connection. The contact pins 16A, 16B of the voltage generator 10 and the contact pins 26A, 26B of the voltage measuring device 12 are kept in a non-contact relationship with each other, and are made conductive only through the input terminals 2A, 2B. Thereby, the input terminals 2A and 2B
The true voltage value applied to the can be measured.

Incidentally, as shown in FIG. 3, the voltage generator 10 is provided at the base points PA and PB of the contact pins 36A and 36B.
And the voltage measuring device 12 are connected, input terminals 2A, 2B
It is not possible to measure the true voltage value applied to the. That is, for example, dust is attached to the input terminals 2A and 2B, and the contact pins 36A and 36B are
Voltage measuring device 1 even if it is not in proper contact with 2B
2 monitors the voltage value from the voltage generator 10.
Therefore, it cannot be determined as abnormal.

On the other hand, according to the method of the present embodiment shown in FIG. 1, since the voltage value is measured only through the input terminals 2A and 2B, when the contact state of the contact pins 16A and 16B is poor. , An improper value is displayed on the voltage measuring device 12, and it can be immediately judged to be abnormal.

As the voltage generator 10, an mV generator which can generate an arbitrary voltage and current with high accuracy and stability can be used. Further, as the voltage measuring device 12, AC, DC
It is possible to use a digital multi-meter (DMM) that measures the voltage, current, and resistance of the digital display.

Next, the previously obtained voltage value is applied to the voltage generator 1
It is applied between 0 and the input terminals 2A and 2B, and whether or not a proper voltage value is applied is monitored by the display of the voltage measuring device 12. The voltage value applied by the voltage generator 10 can be corrected while observing the monitor (display of the voltage measuring device 12). Only when it is confirmed by the voltage measuring device 12 that an appropriate voltage value is applied, the product 1
The digital display value of is adjusted to the display value corresponding to the voltage value (corresponding to the temperature value). By doing so, the display value can be adjusted without being affected by the contact resistance (r1, r2 in FIG. 2) based on the voltage value exactly the same as the value tested by using the resistance.

In the above embodiment, the case where the physical quantity is temperature and the display adjustment of the product having the temperature measuring function is shown, but when the display adjustment of the apparatus for measuring the other physical quantity is performed. However, the present invention can be applied.

[0023]

As described above, according to the present invention, instead of connecting the pseudo resistance between the input terminals, the voltage generator is connected, and the voltage corresponding to the inspection physical quantity is applied between the input terminals from the beginning. When a proper voltage is applied between the input terminals,
Since the display content is adjusted, the display value can be adjusted with almost no influence of the contact resistance value, and accurate adjustment can be performed. Further, since the resistance generator is not necessary, the equipment required for the inspection / adjustment can be downsized.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an implementation status of a display adjustment method according to an embodiment of the present invention.

FIG. 2 is a circuit configuration diagram showing an implementation status of a display adjustment method according to an embodiment of the present invention.

FIG. 3 is a configuration diagram showing a defective example with respect to the present invention.

FIG. 4 is a configuration diagram showing a temperature measurement principle of a conventional temperature controller.

FIG. 5 is a circuit configuration diagram showing a state of implementation of a conventional display adjustment method.

FIG. 6 is a circuit configuration diagram showing the presence of contact resistance in a conventional display adjustment method.

[Explanation of symbols] 1 product (temperature controller main body) 2A, 2B input terminal 3 sensor (detection element) 10 voltage generator 12 voltage measuring device

Claims (1)

[Claims] 1. A voltage between the input terminals, which is generated when a sensing element whose resistance value changes according to a change in a physical quantity to be measured is connected between a pair of input terminals and a constant current is applied to the sensing element. In the display adjustment method of a physical quantity measuring device for converting and displaying a digital value with an A / D converter, a voltage generator for applying a constant voltage is connected between the pair of input terminals, and between the input terminals, A display adjustment of a physical quantity measuring device, characterized in that a voltage measuring device for measuring a voltage applied between the input terminals is connected, and the contents of the display are adjusted when the voltage measuring device measures an appropriate voltage. Method.