JPH05281053A - Temperature detecting device - Google Patents

Abstract

PURPOSE:To provide a temperature detecting device which can continuously measure accurate temperature over a wide range by setting up a value obtained by adding or averaging a partial potential voltage value V1 obtained by using a thermister resistance value on the high temperature side of a measuring use range as a partial potential resistance value as one side and a partial potential voltage value V3 obtained by dividing a partial potential voltage value V2 using the thermister resistance value on a low temperature side as the partial potential resistance value at a certain ratio as the other side as measuring temperature. CONSTITUTION:A temperature detecting device has negative characteristic thermisters 3,4 having the same characteristic, and a partial potential resistance 5 has a resistance value at the high temperature of the thermister. The added value of the resistance values of partial potential resistances 6, 7 has a resistance value at the low temperature of the thermister. The ratio of the resistance values of the resistances 6, 7 is set up so added or averaged value of a voltage V3 between the resistance 7 and a voltage V1 between the resistance 5 may closely resemble their inclinations at high and low temperatures. Accurate temperature can be continuously measured through the added or averaged value of the voltages V1, V3 in a measuring temperature range using a voltage adding or averaging circuit or a computing element 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to general consumer appliances (for example, water heaters, rice cookers, rice cookers, etc.) that require continuous temperature changes within a relatively wide range such as the temperature of liquids, the temperature in closed containers, and the temperature of parts. Electric carpet, each room) etc.

[0002]

2. Description of the Related Art Conventionally, for temperature measurement in general consumer equipment, at the temperature that is most important for the product, the sensitivity of the voltage divided by the negative characteristic thermistor and the voltage dividing resistor becomes the best, At other temperatures, the temperature detector was used, ignoring accuracy. Further, when it is desired to continuously use the temperature detecting device, the measured voltage change in the temperature range is stored in advance in the ROM of the microcomputer or the like.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a temperature detecting device using a negative characteristic thermistor which is inexpensive and easy to measure temperature, and is capable of continuously and accurately measuring temperature in a wide range. is there.

[0004]

Embodiments of the present invention will be described below with reference to the drawings.

First, FIG. 6 shows a conventional temperature detecting device, 1 is a negative characteristic thermistor, 2 is a voltage dividing resistor, V ₁ is a divided voltage value of the voltage dividing resistor 2, and V _CC is a voltage value across both ends. .

FIG. 7 shows the characteristics of the ambient temperature of the negative characteristic thermistor 1 and the divided voltage value V ₁ of the voltage dividing resistor 2. As can be seen from this characteristic curve, the voltage V
_1, clear that the sensitivity is best before and after the V _CC / 2 when the ambient temperature T _o of the thermistor 1, the sensitivity becomes worse also become lower higher than the ambient temperature T _o of the thermistor 1 Is. Further, since V ₁ has an inflection point at a temperature slightly lower than T _o , the rising voltage of V ₁ with respect to the ambient temperature of the thermistor 1 has a substantially constant value before and after the inflection point.

Next, FIG. 1 shows an embodiment of the present invention (claim 2). Reference numeral 3 is a negative characteristic thermistor, 4 is a negative characteristic thermistor having the same characteristic as 3, and 5 is a voltage dividing resistor having a resistance value at a high temperature of the thermistor. Reference numerals 6 and 7 are voltage dividing resistors, and the sum of the resistance value of 6 and the resistance value of 7 has the resistance value of the thermistor at a low temperature, and the ratio of the resistance value of 6 and the resistance value of 7 is 7 Is set to a ratio such that the added value or the average value of the voltage between the resistors and the voltage between the resistors is approximately similar to the slope at high temperature and the slope at low temperature. Between the negative characteristic thermistor 3 and the voltage dividing resistor 5, and between the resistor 6 and the resistor 7, a voltage adding or averaging circuit or a calculator 8 is provided.
Connect.

In FIG. 2, the voltage between the resistors 5 is V [1], the voltage between the resistors 6 + 7 is V [2], and the voltage between the resistors 7 is V [1].
As [3], a characteristic curve of the ambient temperature of the thermistor and the divided voltage of each voltage dividing resistor is shown. Each voltage V
[1], V [2], and V [3] show the characteristics of the inclined flat S-shape, and each has an inflection point. The added value or the average value of the voltages V [1] and V [3] also shows the characteristics of the inclined flat S shape, but since the inclination with respect to the temperature on the low temperature side and the inclination with respect to the temperature on the high temperature side are the same, Although there are 1 to 3 inflection points within the measurement temperature range, the amount of change in the slope within the measurement temperature range is very small compared to the voltages V [1] and V [3]. be able to.
As a result of the experiment, it was found that the amount of change in the slope within the measurement temperature range can be suppressed to 20% or less by appropriately selecting the values of the resistors 5, 6, and 7. Using the voltage addition or averaging circuit or the calculator 8, the voltages V [1] and V
With the added value or the average value of [3], it is possible to continuously and accurately measure the temperature in the measurement temperature range. Further, in the case where the divided voltage is converted by an A / D converter or the like and processed by a microcomputer or the like, V [1] and V [2] are input and V [2] is divided by a fixed ratio. ,
The same result is obtained by adding or averaging the value and the value of V [1].

FIG. 3 shows an embodiment of the present invention (claim 1), which is based on the same theory as that of the embodiment of FIG. 1. In the embodiment of FIG. Although the individual thermistors are used, it is impossible to obtain the thermistors having the same characteristics, and when an expensive thermistor is used, the cost increases.

Therefore, by using one thermistor and switching the voltage dividing resistors in a cycle within a range that does not cause an error in measurement, the voltages of V [1] and V [3] are obtained and within the cycle. Then, the value obtained by adding or averaging the voltages of V [1] and V [3] can be used as the value of the measured temperature.

Reference numerals 9 and 10 denote transistors, 11 denotes a switching signal generator, and the voltage adding or averaging circuit or the arithmetic unit 8 and the switching signal generator 11 can be controlled by a microcomputer.

FIG. 4 shows an embodiment of the present invention (claim 3).

1 is a negative characteristic thermistor, 12 to 18 are resistors, 19 to 22 are transistors, 23 is a voltage measuring device, 2
Reference numeral 4 is a switch. Divide measurement temperature range into 4 and switch 2
4 turns on the transistor 22 and turns off the other transistors 19 to 21, the voltage at the point A becomes a in FIG.
The voltage of the curve like is obtained. The slope of the voltage in this range is about BV / deg. Next, the transistor 21 is turned on, and the other transistors 19, 20,
When 22 is turned off, A
As the point voltage, a voltage having a curve as shown in b of FIG. 5 is obtained. Figure 5
By appropriately selecting the resistance value so that the voltage gradient becomes BV / deg in the range of, the voltage gradient of approximately BV / deg can be obtained in the range of. Similarly, the voltage at the point A can be made to have a slope of about BV / deg as in the range of the c curve and the range of the d curve in FIG. 5, and by switching the transistors 19 to 22 in the measurement range, A constant slope of about BV / deg can be obtained, and this value can be used as the measured temperature value.

The voltage measuring device 23 and the switching device 24 can also be controlled by a microcomputer.

[0015]

As described above, according to the present invention, the measured temperature in a somewhat wide range (50 to 150 deg as an example).
In, the temperature change amount and the temperature can be continuously measured with a small error (about 10% or less), and it is safe and convenient when used for temperature detection of general consumer equipment.

[Brief description of drawings]

FIG. 1 is an embodiment of the present invention (claim 2).

FIG. 2 shows characteristic curves of ambient temperature of the thermistor and divided voltage of each voltage dividing resistor in the embodiment of FIG.

FIG. 3 is an example of the present invention (claim 1).

FIG. 4 is an embodiment of the present invention (described in claim 3).

5 shows characteristic curves of the ambient temperature of the thermistor and the divided voltage of each voltage dividing resistor in the embodiment of FIG.

FIG. 6 is a conventional temperature detecting device.

FIG. 7 shows characteristic curves of the ambient temperature of the thermistor and the divided voltage of the voltage dividing resistor in the conventional temperature detecting device.

[Explanation of symbols]

 1, 3, 4 Negative characteristic thermistor 2, 5-7, 12-18 Voltage dividing resistor 8 Voltage addition or averaging circuit or calculator 9, 10, 19-22 Transistor 23 Voltage measuring device 24 Switcher

Claims (4)

[Claims] 1. A negative characteristic thermistor is used as a heat-sensitive element, a constant voltage is divided by the thermistor and a resistor, and the ambient temperature of the thermistor is measured by the divided voltage value. The resistance that obtains the divided voltage value V [1] with the thermistor resistance value as the divided resistance value and the divided voltage value V [2] obtained with the low temperature side thermistor resistance value as the divided resistance value are at a certain ratio. The divided voltage value V [1] and the divided voltage value V obtained by switching the resistance for obtaining the divided voltage value V [3] in a cycle that does not cause an error in measurement.
A temperature detecting device in which a value obtained by adding or averaging [3] in one cycle is set as a measurement temperature in the cycle so that the inclination becomes constant at least in a measurement use range. 2. A divided voltage value V obtained by using two negative characteristic thermistors having the same characteristic and using one of them as the voltage dividing resistance value of the thermistor resistance value on the high temperature side of the measurement use range.
[1] and the divided voltage value V [2] in which the other one uses the resistance value of the thermistor on the low temperature side of the measurement use range as the dividing resistance value.
The temperature detection device according to claim 1, wherein the measured temperature is a value obtained by adding or averaging the voltage value V [3] obtained by dividing the voltage at a certain ratio. 3. The measurement temperature range is divided, the thermistor resistance value at each temperature within the divided range is set as a voltage dividing resistance value, and the slope of the voltage value at each temperature within each divided temperature range is also in each divided temperature range. The temperature detecting device according to claim 1, wherein a value obtained by dividing the voltage value at a certain ratio so as to be substantially constant is used as the measurement temperature. 4. The voltage obtained by amplifying or dividing the voltage of the negative characteristic thermistor and the voltage dividing resistor to obtain a voltage having a substantially constant slope as measured temperature. The temperature detection device according to any one of 1.