JPH0718727B2 - Flowmeter heater controller - Google Patents
Flowmeter heater controllerInfo
- Publication number
- JPH0718727B2 JPH0718727B2 JP2139741A JP13974190A JPH0718727B2 JP H0718727 B2 JPH0718727 B2 JP H0718727B2 JP 2139741 A JP2139741 A JP 2139741A JP 13974190 A JP13974190 A JP 13974190A JP H0718727 B2 JPH0718727 B2 JP H0718727B2
- Authority
- JP
- Japan
- Prior art keywords
- heater
- resistance
- temperature
- resistor
- ambient temperature
- 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 - Lifetime
Links
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、シリコン等の基台上にヒータ用抵抗と該ヒー
タ用抵抗の近傍に独立して配置された測温抵抗を有する
フローセンサを用いた流量計に関し、特にその流量計の
ヒータ制御装置に関するものである。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention provides a flow sensor having a resistance for a heater on a base made of silicon or the like and a temperature measuring resistance independently arranged near the resistance for the heater. The present invention relates to a flow meter used, and particularly to a heater control device for the flow meter.
流量計としては、例えばシリコンの基台上にヒータ用抵
抗と該ヒータ用抵抗の両側（上流，下流）に独立して配
置された測温抵抗からなるフローセンサ、いわゆるマイ
クロフローセンサを用い、このフローセンサのヒータ用
抵抗から測定流体を介した熱の拡散度合を前記測温抵抗
によって検出することにより、流量を測定するものがあ
る。As the flow meter, for example, a so-called micro flow sensor, which is a flow sensor including a heater resistor and a temperature measuring resistor independently disposed on both sides (upstream and downstream) of the heater resistor on a silicon base, is used. There is one in which the flow rate is measured by detecting the degree of diffusion of heat from the heater resistance of the flow sensor through the measurement fluid by the temperature measuring resistance.
ところで、かかる流量計において用いられている従来の
ヒータ制御装置は、ブリッジ回路の各辺にそれぞれヒー
タ用抵抗，周囲温度測定用リファレンス抵抗を接続し、
これらヒータ用抵抗，リファレンス抵抗の差電圧を増幅
器で検出して、ヒータ用抵抗の温度が周囲温度に関わり
なく、ある一定温度差になるようにコントロールされる
回路構成となっていた。By the way, in the conventional heater control device used in such a flow meter, a heater resistor and an ambient temperature measuring reference resistor are connected to each side of the bridge circuit,
An amplifier detects the difference voltage between the heater resistance and the reference resistance, and the temperature of the heater resistance is controlled to have a certain temperature difference regardless of the ambient temperature.
ところが、このような従来回路は、ヒータ用抵抗により
熱せられた同一チップ上のセンサ（測温抵抗）の感度は
周囲温度が上昇すると、ヒータ用抵抗の温度が一定であ
るにもかかわらず、気体の熱拡散率の温度特性により、
すなわち測定対象の気体の温度が上昇するに従って感度
が低下する。例えば、気体の熱拡散率によりその温度特
性が約4000ppm/℃の割合で周囲温度上昇に伴いセンサの
感度低下を生じるという問題があった。However, in such a conventional circuit, the sensitivity of the sensor (temperature measuring resistance) on the same chip heated by the resistance for the heater increases when the ambient temperature rises, even though the temperature of the resistance for the heater remains constant. Due to the temperature characteristics of the thermal diffusivity of
That is, the sensitivity decreases as the temperature of the gas to be measured increases. For example, there has been a problem that the temperature characteristic of the gas due to the thermal diffusivity of the gas is about 4000 ppm / ° C., and the sensitivity of the sensor is reduced as the ambient temperature rises.
本発明は以上の点に鑑みてなされたもので、周囲温度測
定センサとしてのリファレンス抵抗のもつ温度係数（34
00ppm/℃）を利用して、ヒータ用抵抗に印加する電圧を
その温度係数に正比例させるように可変制御することに
より、センサの温度特性を補正することができる流量計
のヒータ制御装置を提供することを目的する。The present invention has been made in view of the above points, and has a temperature coefficient (34
00ppm / ° C) is used to variably control the voltage applied to the heater resistor so as to be directly proportional to its temperature coefficient, thereby providing a heater control device of a flow meter capable of correcting the temperature characteristic of the sensor. The purpose.
上記の目的を達成するために、本発明に係るヒータ制御
装置は、周囲温度測定用のリファレンス抵抗と該リファ
レンス抵抗に一定電流を流すための固定抵抗とを直列に
接続し、そのリファレンス抵抗と固定抵抗で分圧された
電圧を差動増幅器で増幅して、この出力によりヒータ用
抵抗に供給する電力を制御することによりそのヒータ用
抵抗の温度を周囲温度に応じて可変するようにしたもの
である。In order to achieve the above object, the heater control device according to the present invention includes a reference resistance for measuring an ambient temperature and a fixed resistance for flowing a constant current through the reference resistance, which are connected in series, and fixed with the reference resistance. The voltage divided by the resistor is amplified by a differential amplifier, and the electric power supplied to the heater resistor is controlled by this output so that the temperature of the heater resistor can be changed according to the ambient temperature. is there.
本発明においては、ヒータ用抵抗つまりヒータに印加す
る電圧をその温度係数に正比例させて電力に温度係数を
もたせることにより、周囲温度の上昇に伴いヒータ温度
を上昇させ、センサの温度特性を補正することができ
る。In the present invention, the heater resistance, that is, the voltage applied to the heater is directly proportional to the temperature coefficient of the heater so that the electric power has the temperature coefficient, so that the heater temperature is increased as the ambient temperature is increased and the temperature characteristic of the sensor is corrected. be able to.
以下、本発明を図面に示す実施例に基づいて詳細に説明
する。Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.
図は本発明の一実施例による流量計のヒータ制御装置の
回路構成図である。図において、１はジュール熱により
発熱するヒータ用抵抗、２は周囲温度測定用のリファレ
ンス抵抗、3,4,5および６は固定抵抗、７はリファレン
ス抵抗２と抵抗３で分割された電圧を増幅する差動増幅
器、８はこの差動増幅器７の出力によりヒータ用抵抗１
に供給する電力を制御するトランジスタであり、このト
ランジスタ８とヒータ用抵抗１によりヒータ回路９を構
成している。なお、ヒータ用抵抗１はシリコン等の基台
上の中央部分に配置され、その両側にそれぞれ独立して
測温抵抗（図示せず）が配置れるとともに、その上流側
に周囲温度測定用のリファレンス抵抗２が配置されてい
て、これらヒータ用抵抗１、リファレンス抵抗２及び測
温抵抗により従来例と同様のフローセンサを構成してい
る。FIG. 1 is a circuit configuration diagram of a heater control device for a flow meter according to an embodiment of the present invention. In the figure, 1 is a resistance for a heater which generates heat by Joule heat, 2 is a reference resistance for measuring an ambient temperature, 3, 4, 5 and 6 are fixed resistances, and 7 is a voltage amplified by the reference resistances 2 and 3. The differential amplifier 8 is a resistor 1 for the heater based on the output of the differential amplifier 7.
Is a transistor for controlling the electric power supplied to the heater circuit. The transistor 8 and the heater resistor 1 constitute a heater circuit 9. The heater resistor 1 is arranged in a central portion of a base such as silicon, and a temperature measuring resistor (not shown) is independently arranged on each side of the substrate, and a reference for measuring ambient temperature is provided on the upstream side. A resistor 2 is arranged, and the heater resistor 1, the reference resistor 2, and the temperature measuring resistor constitute a flow sensor similar to the conventional example.
ここで、前記リファレンス抵抗２と抵抗３は直列に接続
され、その一端が電源＋Ｖに、他端が接地されている。
そしてこの直列回路の中点ａの電圧が差動増幅器７の一
方の入力側に加えられ、その他方の入力側が抵抗４を介
して接地されている。この差動増幅器７の出力側は抵抗
６を経てトランジスタ８のベースに接続されていて、そ
のコレクタ側がヒータ用抵抗１を介して接地されるとと
もに、抵抗５を経て差動増幅器７の他方の入力側に接続
されている。Here, the reference resistor 2 and the resistor 3 are connected in series, one end of which is connected to the power supply + V and the other end thereof is grounded.
The voltage at the midpoint a of this series circuit is applied to one input side of the differential amplifier 7, and the other input side is grounded via the resistor 4. The output side of the differential amplifier 7 is connected to the base of a transistor 8 via a resistor 6, the collector side of which is grounded via a heater resistor 1 and the other input of the differential amplifier 7 via a resistor 5. Connected to the side.
上記実施例の構成によると、ヒータ用抵抗１の抵抗値を
RH、リファレンス抵抗２の抵抗値をRR、抵抗３の抵抗値
をRaとしたとき、これらをRa＞＞RRとすると、リファレ
ンス抵抗２にはほぼ一定の電流が流れる。このため、周
囲温度の上昇に伴い接続点ａの電位は上がり、ヒータ用
抵抗１の印加電圧点ｂの電圧をVB、その点ｂにおける電
力をＰとすると、周囲温度Toでは次式で表される。According to the configuration of the above embodiment, the resistance value of the heater resistor 1 is
When R H, the resistance value of the reference resistor 2 and R R, the resistance value of the resistor 3 and R a, these When R a >> R R, a substantially constant current flows through the reference resistor 2. Thus, increases the potential of the connection point a with increasing ambient temperature, the voltage of the applied voltage point b of the heater resistor 1 V B, when the power at the point b is P, the following equation in the ambient temperature T o expressed.
VB＝CRR（１＋αTo） ・・・・(2) ただし、αは温度係数、Ｃは定数であり、(1)式の分母
は温度THにおけるヒータ用抵抗１の抵抗値を示す。ま
た、(2)式の点ｂにおける電圧VBはリファレンス抵抗２
の抵抗値と比例関係にある。よって、(2)式を(1)式へ代
入すると、 ただし、 となる。これにより、１＋αTOの温度係数でヒータ用抵
抗１への印加電力が上昇し、これに伴いヒータ用抵抗１
の温度は１＋αTOの温度係数で上昇して、センサの温度
上昇による感度低下分を補正することができる。 V B = CR R (1 + αT o ) ... (2) where α is a temperature coefficient and C is a constant, and the denominator of the equation (1) represents the resistance value of the heater resistor 1 at the temperature T H. Further, the voltage V B at the point b in the equation (2) is the reference resistance 2
It is proportional to the resistance value of. Therefore, substituting equation (2) into equation (1), However, Becomes As a result, the power applied to the heater resistor 1 increases with the temperature coefficient of 1 + αT O , and the heater resistor 1 increases accordingly.
The temperature of 1 rises with a temperature coefficient of 1 + αT O, and the decrease in sensitivity due to the temperature rise of the sensor can be corrected.
このように本実施例では、周囲温度測定用のリファレン
ス抵抗２のもつ温度係数3400ppm/℃を利用し、ヒータ用
抵抗１つまりヒータ１に印加する電圧VBをその温度係数
に正比例させるようにして、この電力Ｐに温度係数をも
たせることにより、周囲温度の上昇に応じてヒータ１の
温度を上昇させ、センサの温度特性を補正することが可
能になる。As described above, in this embodiment, the temperature coefficient 3400 ppm / ° C. of the reference resistor 2 for measuring the ambient temperature is used, and the voltage V B applied to the heater resistor 1, that is, the heater 1 is directly proportional to the temperature coefficient. By providing the electric power P with a temperature coefficient, it is possible to raise the temperature of the heater 1 according to the rise of the ambient temperature and correct the temperature characteristic of the sensor.
なお、上記実施例ではヒータ用抵抗の両側に同一チップ
上に測温抵抗を配置し、その測温抵抗の周囲温度による
感度を補正する場合について示したが、該測温抵抗が１
つだけでも同様に適用することができる。In the above embodiment, the temperature measuring resistors are arranged on the same chip on both sides of the heater resistor, and the sensitivity of the temperature measuring resistors due to the ambient temperature is corrected.
Only one can be applied as well.
以上説明したように、本発明に係る流量計のヒータ制御
装置によれば、ヒータ用抵抗の温度を周囲温度に対して
正の温度係数で制御することにより、センサの感度の温
度特性がフラットな特性になり、精度の向上が図れる効
果がある。As described above, according to the heater control device of the flowmeter according to the present invention, the temperature characteristic of the sensitivity of the sensor is flat by controlling the temperature of the heater resistor with a positive temperature coefficient with respect to the ambient temperature. It has characteristics and has an effect of improving accuracy.
図は本発明に係るヒータ制御装置の一実施例を示す回路
構成図である。 １……ヒータ用抵抗（ヒータ）、２……リファレンス抵
抗、3,4,5,6……固定抵抗、７……差動増幅器、８……
トランジスタ、９……ヒータ回路。FIG. 1 is a circuit configuration diagram showing an embodiment of a heater control device according to the present invention. 1 ... Heater resistance (heater), 2 ... Reference resistance, 3,4,5,6 ... Fixed resistance, 7 ... Differential amplifier, 8 ...
Transistor, 9 ... Heater circuit.
Claims (1)
近傍に独立して配置された測温抵抗を有するフローセン
サを備え、このフローセンサのヒータ用抵抗から測定液
体を介した熱の拡散度合を前記測温抵抗によって検出す
ることにより、液量を測定する流量計において、前記基
台上に一体に形成された周囲温度測定用のリファレンス
抵抗と該リファレンス抵抗に一定電流を流すための固定
抵抗とを直列に接続した直列回路と、前記リファレンス
抵抗と固定抵抗で分圧された電圧を増幅する差動増幅器
と、該差動増幅器の出力により前記ヒータ用抵抗に供給
する電力を制御して、そのヒータ用抵抗の温度を周囲温
度に応じて可変するように構成されたヒータ回路を具備
したことを特徴とする流量計のヒータ制御装置。1. A flow sensor having a resistance for a heater and a resistance for temperature measurement independently arranged near the resistance for the heater is provided on a base, and heat from the resistance for the heater of the flow sensor is passed through a measurement liquid. In the flowmeter for measuring the amount of liquid by detecting the diffusion degree of the temperature measuring resistance, a reference resistance for ambient temperature measurement integrally formed on the base and a constant current flow to the reference resistance. , A series circuit in which the fixed resistance of the fixed resistance is connected in series, a differential amplifier that amplifies the voltage divided by the reference resistance and the fixed resistance, and the power supplied to the heater resistance is controlled by the output of the differential amplifier. Then, the heater control device for the flow meter is provided with a heater circuit configured to change the temperature of the heater resistor according to the ambient temperature.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2139741A JPH0718727B2 (en) | 1990-05-31 | 1990-05-31 | Flowmeter heater controller |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2139741A JPH0718727B2 (en) | 1990-05-31 | 1990-05-31 | Flowmeter heater controller |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0434315A JPH0434315A (en) | 1992-02-05 |
| JPH0718727B2 true JPH0718727B2 (en) | 1995-03-06 |
Family
ID=15252299
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2139741A Expired - Lifetime JPH0718727B2 (en) | 1990-05-31 | 1990-05-31 | Flowmeter heater controller |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0718727B2 (en) |
-
1990
- 1990-05-31 JP JP2139741A patent/JPH0718727B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0434315A (en) | 1992-02-05 |
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