JPH0449898B2 - - Google Patents
Info
- Publication number
- JPH0449898B2 JPH0449898B2 JP2553285A JP2553285A JPH0449898B2 JP H0449898 B2 JPH0449898 B2 JP H0449898B2 JP 2553285 A JP2553285 A JP 2553285A JP 2553285 A JP2553285 A JP 2553285A JP H0449898 B2 JPH0449898 B2 JP H0449898B2
- Authority
- JP
- Japan
- Prior art keywords
- voltage
- thermistor
- diode
- temperature
- resistor
- 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.)
- Expired
Links
- 238000001514 detection method Methods 0.000 claims description 16
- 230000000694 effects Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000009529 body temperature measurement Methods 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
- G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
- G01K7/22—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a non-linear resistance, e.g. thermistor
- G01K7/24—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a non-linear resistance, e.g. thermistor in a specially-adapted circuit, e.g. bridge circuit
Description
【発明の詳細な説明】
産業上の利用分野
本発明はサーミスタを用いた温度検出装置に関
するものである。DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a temperature detection device using a thermistor.
従来の技術
近年、温度検出装置を用いて各種の制御動作を
行う装置が普及してきているが、サーミスタを温
度センサとして用いる場合、サーミスタが断線す
ると、測定系としてはサーミスタが非常に高抵抗
になつたと判断さることによつて、検出温度が非
常に低いと認識する方向となる。特にヒータ制御
を行うような系では、このような状態になると、
検出温度が低いと認識するので、真の温度とは無
関係に常にヒータに通電する結果となり、場合に
よつては火災等の非常に危険な結果を招くことに
なる。Conventional Technology In recent years, devices that use temperature detection devices to perform various control operations have become popular. However, when using a thermistor as a temperature sensor, if the thermistor is disconnected, the thermistor becomes extremely high resistance as a measurement system. By determining that the detected temperature is very low, the detected temperature is recognized as being very low. Particularly in systems that control heaters, if this situation occurs,
Since the detected temperature is recognized to be low, the heater is always energized regardless of the true temperature, which may lead to extremely dangerous consequences such as fire.
従つて、サーミスタを用いた温度検出装置で
は、サーミスタの断線検出機能を必ず有するもの
でなければならない。一般的にサーミスタを用い
た温度検出装置では、サーミスタと抵抗を直列に
接続してこれらの抵抗値の比によつて温度検出し
ているが、従来はサーミスタがある一定の抵抗値
より大きくなつた場合を検出してサーミスタ断線
を判定していた。その場合、判定基準となる抵抗
値は考えられる範囲で最も低い温度に相当する抵
抗値以上の大きさで設定されていた。 Therefore, a temperature detection device using a thermistor must always have a thermistor disconnection detection function. Generally, temperature detection devices using a thermistor connect a thermistor and a resistor in series and detect temperature based on the ratio of these resistance values. The thermistor disconnection was determined by detecting the case. In that case, the resistance value used as the criterion was set to be greater than or equal to the resistance value corresponding to the lowest temperature within the conceivable range.
発明が解決しようとする問題点
このような方法では、サーミスタの断線検出状
態と低温時における高抵抗状態との区別があいま
いになり、断線検出時の抵抗値の設定が困難にな
つたり、幅広いレンジでの温度検出が不可能にな
つたりする場合が生じる。Problems to be Solved by the Invention In such a method, the distinction between the disconnection detection state of the thermistor and the high resistance state at low temperatures becomes vague, making it difficult to set the resistance value when detecting a disconnection, and making it difficult to set the resistance value when detecting a disconnection. Temperature detection may become impossible.
本発明はこのような問題を解決するもので、断
線状態と高抵抗状態とを区別し易くした温度検出
装置を提供することを目的とするものである。 The present invention is intended to solve such problems, and an object of the present invention is to provide a temperature detection device that makes it easy to distinguish between a disconnected state and a high resistance state.
問題点を解決するための手段
上記問題点を解決するために本発明は、温度検
出用のサーミスタと、このサーミスタに直列接続
した分圧発生用の抵抗および順方向にバイアスさ
れるダイオードと、前記サーミスタと抵抗および
ダイオードとの接続点を一方の入力端子に接続し
基準電圧発生部の出力端子を他方の入力端子に接
続した電圧比較器とを備え、前記電圧比較器は一
方の入力端子に分圧発生用の抵抗の両端電圧に加
えて前記ダイオードの順方向電圧を入力し、前記
ダイオードの順方向電圧により前記サーミスタの
断線を判断するようにしたものである。Means for Solving the Problems In order to solve the above problems, the present invention includes a thermistor for temperature detection, a resistor for generating a partial voltage connected in series with the thermistor, a diode biased in the forward direction, and a diode biased in the forward direction. A voltage comparator is provided, in which the connection point between the thermistor, the resistor, and the diode is connected to one input terminal, and the output terminal of the reference voltage generator is connected to the other input terminal, and the voltage comparator is divided into one input terminal. In addition to the voltage across the voltage generating resistor, the forward voltage of the diode is input, and disconnection of the thermistor is determined based on the forward voltage of the diode.
作 用
上記構成によれば、サーミスタが高抵抗となる
場合はダイオードに流れる電流によつて発生する
順方向電圧降下分の電圧が残つて電圧比較器に入
力され、一方、サーミスタが完全に断線した場合
はこの電圧が零になるという特性を有するため、
断線状態と低温時の高抵抗状態とを区別すること
ができるものである。Effects According to the above configuration, when the thermistor has a high resistance, the voltage corresponding to the forward voltage drop generated by the current flowing through the diode remains and is input to the voltage comparator. Since this voltage has the characteristic that it becomes zero,
It is possible to distinguish between a disconnected state and a high resistance state at low temperatures.
実施例
以下、本発明の一実施例を第１図にもとづいて
説明する。この第１図において、１は温度検出用
のサーミスタ、２は分圧発生用の抵抗、３はダイ
オード、４は電圧比較器、５は基準電圧発生部で
ある。前記サーミスタ１は前記抵抗２とダイオー
ド３とを直列接続したものに直列接続され、この
接続点は電圧比較器４の一方の入力端子に接続さ
れ、前記基準電圧発生部５の出力端子が前記電圧
比較器４の他方の入力端子に接続される。６は電
圧比較器４の出力端子、７はサーミスタ１、抵抗
２、ダイオード３に一定電圧を印加する定電圧印
加端子である。Embodiment Hereinafter, an embodiment of the present invention will be described based on FIG. In FIG. 1, 1 is a thermistor for temperature detection, 2 is a resistor for generating partial voltage, 3 is a diode, 4 is a voltage comparator, and 5 is a reference voltage generator. The thermistor 1 is connected in series with the resistor 2 and the diode 3 connected in series, this connection point is connected to one input terminal of the voltage comparator 4, and the output terminal of the reference voltage generator 5 is connected to the voltage It is connected to the other input terminal of comparator 4. 6 is an output terminal of the voltage comparator 4, and 7 is a constant voltage application terminal that applies a constant voltage to the thermistor 1, resistor 2, and diode 3.
次に本実施例の動作を説明する。サーミスタ１
は周囲温度が高い場合は抵抗値が低く、逆に周囲
温度が低い場合は抵抗値が高い特性を有するもの
で、従つて定電圧印加端子７に一定電圧が加わる
と、第１図に示す電圧Vioは温度によつて変化す
る。このVioの温度に対する変化の様子を第２図
に示す。８はダイオード３がない場合の変化、９
は本実施例の変化を示す。基準電圧発生部５の出
力電圧、すなわち電圧比較器４の反転入力端子の
電圧を変化させて、電圧比較器４の出力端子６の
出力電圧が反転するときの基準電圧発生部５の出
力電圧を求めると、第２図の特性によつて温度を
検出することができる。 Next, the operation of this embodiment will be explained. Thermistor 1
has a characteristic that the resistance value is low when the ambient temperature is high, and conversely, the resistance value is high when the ambient temperature is low. Therefore, when a constant voltage is applied to the constant voltage application terminal 7, the voltage shown in FIG. V io changes with temperature. Figure 2 shows how V io changes with temperature. 8 is the change without diode 3, 9
indicates changes in this embodiment. By changing the output voltage of the reference voltage generation section 5, that is, the voltage at the inverting input terminal of the voltage comparator 4, the output voltage of the reference voltage generation section 5 when the output voltage at the output terminal 6 of the voltage comparator 4 is inverted is determined. Once determined, the temperature can be detected using the characteristics shown in FIG.
サーミスタ１が断線した場合はVio＝０となる
ので、零より大きく、かつできるだけ小さい断線
検出判定用の基準電圧を設定し、上記方法で検出
されるVioがこの基準電圧より小さければ断線と
みなす。しかし電圧比較器４の性能および耐ノイ
ズの問題から、この比較を的確に行うには前述の
基準電圧の下限は0.1V程度と考えられる。本実
施例におけるこの断線検出判定用基準電圧を第２
図中のVpに示す。 If the thermistor 1 is disconnected, V io = 0, so set a reference voltage for disconnection detection judgment that is greater than zero and as small as possible, and if V io detected by the above method is smaller than this reference voltage, it is determined that it is disconnected. I reckon. However, due to the performance and noise resistance of the voltage comparator 4, the lower limit of the reference voltage mentioned above is considered to be about 0.1V in order to perform this comparison accurately. This reference voltage for disconnection detection judgment in this embodiment is
It is shown as V p in the figure.
ダイオード３がない場合、第２図の８では、０
℃以下でこの断線検出領域となり、これ以下の温
度ではサーミスタ１が断線していると検知する。
制御系中では断線を検知すると、一般的には動作
を安全側にシフトさせる。すなわち、ヒータ制御
のような系ではヒータへの通電を停止するように
働く。このような場合、本来低温であるので、ヒ
ータへは通電しなければならないにもかかわら
ず、断線検出が優先されて通電が停止するとうい
ような不都合が生じる。 If there is no diode 3, at 8 in Fig. 2, 0
C. or lower, this disconnection detection range occurs, and at temperatures below this temperature, it is detected that the thermistor 1 is disconnected.
In a control system, when a disconnection is detected, the operation is generally shifted to the safe side. That is, in a system such as a heater control system, it works to stop energizing the heater. In such a case, since the temperature is originally low, even though the heater should be energized, priority is given to detecting a disconnection and the energization is stopped.
しかるに本実施例では、第２図の９に示すよう
に、ダイオード３があるために、低温においてサ
ーミスタ１が高抵抗となつても、わずかに流れる
電流によつて発生するダイオード３の順方向電圧
降下（40μAでも0.5V程度ある）によつてVioは低
下せず、従つて−20℃になつても断線検出領域に
なることはない。しかし、サーミスタ１が完全に
断線すると、電流は全く流れなくなるので、ダイ
オード３の順方向電圧降下も零となつてVio＝０
となり、その結果、確実に断線検出を行うことが
できる。 However, in this embodiment, as shown at 9 in FIG. 2, because of the presence of the diode 3, even if the thermistor 1 has a high resistance at low temperatures, the forward voltage of the diode 3 generated by a slight current flowing Vio does not drop due to a voltage drop (approximately 0.5V even at 40 μA), and therefore does not fall into the disconnection detection range even if the temperature reaches -20°C. However, if thermistor 1 is completely disconnected, no current will flow at all, and the forward voltage drop across diode 3 will also become zero, resulting in V io = 0.
As a result, disconnection can be detected reliably.
またダイオード３がない場合において、抵抗２
を大きくすることにより、断線検出と誤検知され
る温度を幾分低くすることはできるが、本実施例
を場合程の効果はなく、第２図に示す直線性を有
する温度測定範囲も低温側へシフトするものであ
る。 In addition, when there is no diode 3, the resistor 2
By increasing , it is possible to somewhat lower the temperature that is falsely detected as a disconnection, but the effect is not as great as in this example, and the temperature measurement range with linearity shown in Figure 2 is also on the low temperature side. This is a shift to
発明の効果
以上のように本発明によれば、電圧比較器は一
方の入力端子に分圧発生用の抵抗の両端電圧に加
えてダイオードの順方向電圧を入力し、前記ダイ
オードの順方向電圧によりサーミスタの断線の有
無を判断するようにしたから、サーミスタに流れ
る電流によるダイオードの順方向電圧の有無によ
つて、低温時のサーミスタの高抵抗状態と断線状
態とを明確に区別することができることができる
ため、低温時における誤動作ということはなくな
り、その効果は非常に大きいものである。Effects of the Invention As described above, according to the present invention, the voltage comparator inputs the voltage across the resistor for voltage division generation as well as the forward voltage of the diode to one input terminal, and the forward voltage of the diode Since we decided to determine whether the thermistor is disconnected, we can clearly distinguish between the high resistance state of the thermistor at low temperatures and the disconnection state based on the presence or absence of forward voltage of the diode due to the current flowing through the thermistor. This eliminates the possibility of malfunctions at low temperatures, which is extremely effective.
第１図は本発明装置の一実施例を示す回路図、
第２図は第１図に示すVioの温度による変化を示
す特性図である。
１……サーミスタ、２……分圧発生用の抵抗、
３……ダイオード、４……電圧比較器、５……基
準電圧発生部。
FIG. 1 is a circuit diagram showing an embodiment of the device of the present invention;
FIG. 2 is a characteristic diagram showing changes in V io shown in FIG. 1 depending on temperature. 1...Thermistor, 2...Resistance for generating partial voltage,
3... Diode, 4... Voltage comparator, 5... Reference voltage generator.
Claims (1)
に直列接続した分圧発生用の抵抗および順方向に
バイアスされるダイオードと、前記サーミスタと
抵抗およびダイオードとの接続点を一方の入力端
子に接続し基準電圧発生部の出力端子を他方の入
力端子に接続した電圧比較器とを備え、前記電圧
比較器は一方の入力端子に分圧発生用の抵抗の両
端電圧に加えて前記ダイオードの順方向電圧を入
力し、前記ダイオードの順方向電圧により前記サ
ーミスタの断線の有無を判断するようにしてなる
温度検出装置。1 A thermistor for temperature detection, a resistor for generating partial voltage connected in series with this thermistor, and a forward biased diode, and the connection point between the thermistor, the resistor, and the diode connected to one input terminal, and a reference voltage and a voltage comparator in which the output terminal of the generator is connected to the other input terminal, and the voltage comparator inputs the forward voltage of the diode in addition to the voltage across the resistor for dividing voltage generation to one input terminal. The temperature detection device is configured to determine whether or not the thermistor is disconnected based on the forward voltage of the diode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2553285A JPS61184431A (en) | 1985-02-13 | 1985-02-13 | Temperature detection apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2553285A JPS61184431A (en) | 1985-02-13 | 1985-02-13 | Temperature detection apparatus |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61184431A JPS61184431A (en) | 1986-08-18 |
| JPH0449898B2 true JPH0449898B2 (en) | 1992-08-12 |
Family
ID=12168633
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2553285A Granted JPS61184431A (en) | 1985-02-13 | 1985-02-13 | Temperature detection apparatus |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61184431A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3687472B2 (en) | 2000-03-13 | 2005-08-24 | 豊田工機株式会社 | Temperature detection device |
| HUE060036T2 (en) * | 2004-08-20 | 2023-01-28 | Fisher & Paykel Healthcare Ltd | Apparatus for measuring properties of gases supplied to a patient |
-
1985
- 1985-02-13 JP JP2553285A patent/JPS61184431A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61184431A (en) | 1986-08-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EXPY | Cancellation because of completion of term |