JPH06137963A - Temperature detecting circuit employing thermister - Google Patents
Temperature detecting circuit employing thermisterInfo
- Publication number
- JPH06137963A JPH06137963A JP28485892A JP28485892A JPH06137963A JP H06137963 A JPH06137963 A JP H06137963A JP 28485892 A JP28485892 A JP 28485892A JP 28485892 A JP28485892 A JP 28485892A JP H06137963 A JPH06137963 A JP H06137963A
- Authority
- JP
- Japan
- Prior art keywords
- thermistor
- thermister
- temperature
- resistor
- current flowing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Measuring Temperature Or Quantity Of Heat (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】この発明は、温度センサとしてサ
ーミスタを用いた温度検出回路、特にその改良に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature detecting circuit using a thermistor as a temperature sensor, and more particularly to an improvement thereof.
【０００２】[0002]
【従来の技術】図３に従来のこの種の温度検出回路を示
す。同図からも明らかなように、この回路はサーミスタ
１に基準抵抗２を接続し、これに所定電圧Ｖを印加して
基準抵抗２の端子電圧Ｖ0 を求め、電圧Ｖ，端子電圧Ｖ
0 および基準抵抗値Ｒｓなどから、温度を検出するもの
である。すなわち、Ｖ，Ｖ0 ，Ｒｓの間には、 Ｖ0 ＝Ｒｓ・Ｖ／（Ｒｓ＋Ｒｔｈ） …（１） の関係が成立するので、この（１）式からＲｔｈを求
め、この値と温度との対照表などから温度を検出するも
のである。2. Description of the Related Art FIG. 3 shows a conventional temperature detecting circuit of this type. As is apparent from the figure, in this circuit, the reference resistance 2 is connected to the thermistor 1, and a predetermined voltage V is applied to this to obtain the terminal voltage V 0 of the reference resistance 2, and the voltage V, the terminal voltage V
The temperature is detected from 0 and the reference resistance value Rs. That is, since the relationship of V 0 = Rs · V / (Rs + Rth) (1) is established between V, V 0 and Rs, Rth is obtained from this equation (1), and this value and temperature are The temperature is detected from a control table or the like.
【０００３】[0003]
【発明が解決しようとする課題】しかしながら、上述の
ような回路で例えばサーミスタに電流Ｉｔｈが流れたと
すると、サーミスタでは（Ｉｔｈ）2 ・Ｒｔｈの電力を
消費するため、これによって自己発熱してしまい、温度
検出精度が低下するという問題がある。したがって、こ
の発明の課題はサーミスタ電流を小さくし、温度検出精
度を低下させないようにすることにある。However, if a current Ith flows through the thermistor in the circuit as described above, for example, the thermistor consumes (Ith) 2 · Rth power, which causes self-heating. There is a problem that the temperature detection accuracy decreases. Therefore, an object of the present invention is to reduce the thermistor current so as not to lower the temperature detection accuracy.
【０００４】[0004]
【課題を解決するための手段】このような課題を解決す
るため、この発明では、温度センサとしてのサーミスタ
に対し、基準抵抗を直列に接続して一定の電圧を印加
し、この電圧，前記基準抵抗の端子電圧および基準抵抗
値から温度を検出するようにしたサーミスタを用いた温
度検出回路において、前記サーミスタと並列に所定の抵
抗を接続することにより、サーミスタに流れる電流を減
少させることを特徴としている。また、この発明では、
前記基準抵抗に代えて定電流回路を接続することによ
り、サーミスタに流れる電流をほぼ一定にすることがで
きる。In order to solve such a problem, according to the present invention, a reference resistor is connected in series to a thermistor as a temperature sensor to apply a constant voltage. In a temperature detection circuit using a thermistor configured to detect a temperature from a terminal voltage of a resistor and a reference resistance value, a current flowing through the thermistor is reduced by connecting a predetermined resistor in parallel with the thermistor. There is. Further, in the present invention,
By connecting a constant current circuit instead of the reference resistor, the current flowing through the thermistor can be made almost constant.
【０００５】[0005]
【作用】サーミスタと並列に抵抗を接続するか、または
サーミスタと直列に定電流回路を接続して、サーミスタ
に流れる電流を減少させるかまたはほぼ一定にし、自己
発熱を低く抑えることにより、良好な温度検出精度を維
持し得るようにする。[Operation] By connecting a resistor in parallel with the thermistor, or by connecting a constant current circuit in series with the thermistor, the current flowing in the thermistor can be reduced or made almost constant, and self-heating can be suppressed to a good temperature. Ensure that detection accuracy can be maintained.
【０００６】[0006]
【実施例】図１はこの発明の実施例を示す回路図であ
る。同図からも明らかなように、この実施例はサーミス
タと並列に抵抗（電流バイパス用抵抗）Ｒａを接続し、
これによってサーミスタに流れる電流を減少させるよう
にしたものである。この場合は、先の（１）式のＲｔｈ
をこれと抵抗Ｒａとの合成抵抗Ｒに置き換えて考えれ
ば、（１）式をそのまま用いることができる。したがっ
て、サーミスタに流れる電流を減少させつつ、温度を検
出することが可能となる。1 is a circuit diagram showing an embodiment of the present invention. As is apparent from the figure, in this embodiment, a resistor (current bypass resistor) Ra is connected in parallel with the thermistor,
With this, the current flowing through the thermistor is reduced. In this case, Rth of the above equation (1)
If the above is replaced with a combined resistance R of this and the resistance Ra, the equation (1) can be used as it is. Therefore, it becomes possible to detect the temperature while reducing the current flowing through the thermistor.
【０００７】図２はこの発明の他の実施例を示す回路図
である。これは、従来回路の基準抵抗２の代わりに、定
電流源としてトランジスタ４（Ｑａ）を接続することに
よりそのコレクタ電流を制限し、サーミスタに流れる電
流Ｉｔｈを従来よりも小さな或る一定値に抑えようとす
るものである。なお、この場合の関係式は、 Ｖ0 ＝Ｖ−Ｉｔｈ・Ｒｔｈ …（２） のように表わすことができる。FIG. 2 is a circuit diagram showing another embodiment of the present invention. This is to limit the collector current of the thermistor by connecting a transistor 4 (Qa) as a constant current source instead of the reference resistor 2 of the conventional circuit, and to suppress the current Ith flowing through the thermistor to a certain constant value smaller than the conventional one. It is something to try. The relational expression in this case can be expressed as follows: V 0 = V−Ith · Rth (2)
【０００８】このように、サーミスタに流れる電流を減
少させるか、ほぼ一定の値に抑えることにより、自己発
熱を最小限に抑え、温度検出精度を低下させないように
することができる。As described above, by reducing the current flowing through the thermistor or suppressing it to a substantially constant value, it is possible to minimize self-heating and prevent the temperature detection accuracy from deteriorating.
【０００９】[0009]
【発明の効果】この発明によれば、サーミスタに流れる
電流を減少させるか、ほぼ一定の値に抑えるようにした
ので、自己発熱が最小限に抑えられ、一定の温度検出精
度を維持することができる利点が得られる。According to the present invention, since the current flowing through the thermistor is reduced or suppressed to a substantially constant value, self-heating is suppressed to a minimum and a constant temperature detection accuracy can be maintained. The advantage that can be obtained is obtained.
【図１】この発明の実施例を示す回路図である。FIG. 1 is a circuit diagram showing an embodiment of the present invention.
【図２】この発明の他の実施例を示す回路図である。FIG. 2 is a circuit diagram showing another embodiment of the present invention.
【図３】従来例を示す回路図である。FIG. 3 is a circuit diagram showing a conventional example.
１…サーミスタ、２…基準抵抗、３…電流バイパス用抵
抗、４…電流制限トランジスタ（Ｑａ）。1 ... Thermistor, 2 ... Reference resistance, 3 ... Current bypass resistance, 4 ... Current limiting transistor (Qa).
Claims (2)
基準抵抗を直列に接続して一定の電圧を印加し、この電
圧，前記基準抵抗の端子電圧および基準抵抗値から温度
を検出するようにしたサーミスタを用いた温度検出回路
において、 前記サーミスタと並列に所定の抵抗を接続することによ
り、サーミスタに流れる電流を減少させることを特徴と
するサーミスタを用いた温度検出回路。1. A thermistor as a temperature sensor,
In a temperature detection circuit using a thermistor configured to detect a temperature from this voltage, a terminal voltage of the reference resistor and a reference resistance value by applying a constant voltage by connecting the reference resistors in series, and in parallel with the thermistor. A temperature detection circuit using a thermistor, characterized in that a current flowing through the thermistor is reduced by connecting a predetermined resistor.
基準抵抗を直列に接続して一定の電圧を印加し、この電
圧，前記基準抵抗の端子電圧および基準抵抗値から温度
を検出するようにしたサーミスタを用いた温度検出回路
において、 前記基準抵抗に代えて定電流回路を接続することによ
り、サーミスタに流れる電流をほぼ一定にすることを特
徴とするサーミスタを用いた温度検出回路。2. A thermistor as a temperature sensor,
In a temperature detection circuit using a thermistor configured to connect a reference resistance in series and apply a constant voltage, and detect the temperature from this voltage, the terminal voltage of the reference resistance and the reference resistance value, instead of the reference resistance, A temperature detection circuit using a thermistor characterized in that the current flowing through the thermistor is made substantially constant by connecting a constant current circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28485892A JPH06137963A (en) | 1992-10-23 | 1992-10-23 | Temperature detecting circuit employing thermister |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28485892A JPH06137963A (en) | 1992-10-23 | 1992-10-23 | Temperature detecting circuit employing thermister |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH06137963A true JPH06137963A (en) | 1994-05-20 |
Family
ID=17683943
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP28485892A Pending JPH06137963A (en) | 1992-10-23 | 1992-10-23 | Temperature detecting circuit employing thermister |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH06137963A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6824308B2 (en) * | 2002-11-07 | 2004-11-30 | Omron Corporation | Temperature detecting device |
| CN110388993A (en) * | 2019-07-02 | 2019-10-29 | 杨晨 | A kind of Low ESR temperature sensor and its thermometry |
-
1992
- 1992-10-23 JP JP28485892A patent/JPH06137963A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6824308B2 (en) * | 2002-11-07 | 2004-11-30 | Omron Corporation | Temperature detecting device |
| CN110388993A (en) * | 2019-07-02 | 2019-10-29 | 杨晨 | A kind of Low ESR temperature sensor and its thermometry |
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