JPH0431535Y2 - - Google Patents
Info
- Publication number
- JPH0431535Y2 JPH0431535Y2 JP1985111168U JP11116885U JPH0431535Y2 JP H0431535 Y2 JPH0431535 Y2 JP H0431535Y2 JP 1985111168 U JP1985111168 U JP 1985111168U JP 11116885 U JP11116885 U JP 11116885U JP H0431535 Y2 JPH0431535 Y2 JP H0431535Y2
- Authority
- JP
- Japan
- Prior art keywords
- signal
- operational amplifier
- pressure sensor
- offset
- output
- 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
- 238000005259 measurement Methods 0.000 claims description 21
- 238000009530 blood pressure measurement Methods 0.000 claims description 13
- 238000001514 detection method Methods 0.000 claims description 9
- 230000036772 blood pressure Effects 0.000 description 5
- 230000003321 amplification Effects 0.000 description 4
- 230000010354 integration Effects 0.000 description 4
- 238000003199 nucleic acid amplification method Methods 0.000 description 4
- 239000003990 capacitor Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 101150015217 FET4 gene Proteins 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 230000005669 field effect Effects 0.000 description 1
Description
【考案の詳細な説明】
〔産業上の利用分野〕
この考案は、血圧計、風圧計などの圧力を測定
する圧力検出装置に関する。[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a pressure detection device for measuring pressure such as a blood pressure monitor or an anemometer.
一般に、電子血圧計等に用いられる圧力センサ
の等価回路は第２図に示すようになつており、同
図において、１はホイーストンブリツジ回路を構
成する４個のピエゾ抵抗素子１ａ〜１ｄからなる
圧力センサ、２ａ，２ｂはそれぞれ抵抗素子１
ａ，１ｂの接続点および抵抗素子１ｃ，１ｄの接
続点に接続され定電流回路からなる駆動電源に接
続される入力端子、３ａ，３ｂはそれぞれ抵抗素
子１ａ，１ｃの接続点および抵抗素子１ｂ，１ｄ
の接続点に接続された出力端子であり、両入力端
子２ａ，２ｂ間に前記電源による定電流を通流し
ておき、センサへの圧力に応じた各抵抗素子１ａ
〜１ｄの抵抗変化により、両出力端子３ａ，３ｂ
間に電位差が生じ、前記電位差を測定することに
よりセンサ１に加わる圧力が測定されることにな
る。
In general, the equivalent circuit of a pressure sensor used in an electronic blood pressure monitor, etc. is shown in Figure 2. In the figure, 1 represents four piezoresistive elements 1a to 1d that constitute a Wheatstone bridge circuit. The pressure sensors 2a and 2b are each resistive element 1.
Input terminals 3a and 3b are connected to the connection point of resistance elements 1a and 1b and the connection point of resistance elements 1c and 1d, respectively, and are connected to a drive power source consisting of a constant current circuit. 1d
It is an output terminal connected to the connection point of
Due to a resistance change of ~1d, both output terminals 3a, 3b
A potential difference is generated between them, and by measuring the potential difference, the pressure applied to the sensor 1 is measured.
つぎに、従来の血圧計等の圧力検出装置の回路
構成を示す第３図および第４図について説明す
る。 Next, FIGS. 3 and 4 showing the circuit configuration of a conventional pressure detection device such as a blood pressure monitor will be described.
まず第３図に示す装置は、CQ出版株式会社発
行の雑誌「トランジスタ技術」1984年11月号の
P328に記載されたデジタル温度計のセンサ回路、
基準電源およびアンプの構成を圧力検出装置に適
用した場合を示し、４は直流電源端子、５，６は
電源端子４とアースとの間に直列に設けられた分
圧用第１，第２抵抗、７は非反転入力端子（＋）
が両抵抗５，６の接続点に接続された第１オペア
ンプ、８は第１オペアンプ７の反転入力端子
（−）とアースとの間に設けられたゲイン設定用
第３抵抗であり、電源端子４、各抵抗５，６，８
および第１オペアンプ７により駆動電源としての
定電流回路９が構成されている。 First, the device shown in Figure 3 was published in the November 1984 issue of the magazine "Transistor Technology" published by CQ Publishing Co., Ltd.
Digital thermometer sensor circuit described on P328,
This shows a case where the configuration of the reference power supply and amplifier is applied to the pressure detection device, where 4 is a DC power supply terminal, 5 and 6 are first and second resistors for voltage division provided in series between the power supply terminal 4 and the ground, 7 is non-inverting input terminal (+)
is the first operational amplifier connected to the connection point of both resistors 5 and 6, 8 is the third resistor for gain setting provided between the inverting input terminal (-) of the first operational amplifier 7 and the ground, and the power supply terminal 4, each resistance 5, 6, 8
The first operational amplifier 7 constitutes a constant current circuit 9 as a drive power source.
１０は一端が圧力センサ１の抵抗素子１ａの入
力側の一端に接続された限流用第４抵抗、１１は
両端が第４抵抗１０の他端および圧力センサ１の
抵抗素子１ｂの入力側の一端に接続された可変抵
抗からなる第５抵抗であり、圧力センサ１の入力
端子２ａに相当する摺動端子が第１オペアンプ７
の出力端子に接続され、圧力センサ１のオフセツ
ト電圧が零になるように前記摺動端子の位置が設
定される。 Reference numeral 10 indicates a current-limiting fourth resistor whose one end is connected to one end of the input side of the resistance element 1a of the pressure sensor 1, and reference numeral 11 indicates the other end of the fourth resistance 10 and one end of the input side of the resistance element 1b of the pressure sensor 1. A sliding terminal corresponding to the input terminal 2a of the pressure sensor 1 is connected to the first operational amplifier 7.
The position of the sliding terminal is set so that the offset voltage of the pressure sensor 1 becomes zero.
なお、圧力センサ１の入力端子２ｂは第１オペ
アンプ７の反転入力端子（−）に接続され、電源
端子４への電源電圧をＥとし、各抵抗５，６，８
の抵抗値をそれぞれR1，R2，R3とすると、
Ｉ＝Ｅ・R2／R1＋R2・１／R3
で表わされる定電流Ｉがセンサ１に供給されるこ
とになる。 The input terminal 2b of the pressure sensor 1 is connected to the inverting input terminal (-) of the first operational amplifier 7, the power supply voltage to the power supply terminal 4 is E, and each of the resistors 5, 6, 8
Assuming that the resistance values of are respectively R 1 , R 2 , and R 3 , a constant current I expressed as I=E·R 2 /R 1 +R 2 ·1/R 3 is supplied to the sensor 1.
１２，１３はそれぞれ一端が圧力センサ１の出
力端子３ａ，３ｂに接続されたゲイン設定用第
６，第７抵抗、１４は反転、非反転入力端子
（−），（＋）がそれぞれ抵抗１２，１３の他端に
接続された第２オペアンプ、１５は第２オペアン
プ１４の非反転入力端子（＋）とアースとの間に
設けられたゲイン設定用第８抵抗、１６は第２オ
ペアンプ１４の反転入力端子（−）と出力端子と
の間に設けられた帰還用第９抵抗であり、各抵抗
１２，１３，１５，１６および第２オペアンプ１
４により差動増幅回路が構成され、圧力センサ１
の両出力端子３ａ，３ｂそれぞれの電位が前記差
動増幅回路に入力されて前記両電位の差が増幅さ
れ、前記電位の差にもとづく電圧信号が出力され
る。 12 and 13 are sixth and seventh resistors for gain setting whose one ends are respectively connected to the output terminals 3a and 3b of the pressure sensor 1, and 14 are inverting and non-inverting input terminals (-) and (+), respectively, are resistors 12, A second operational amplifier connected to the other end of 13; 15 an eighth resistor for gain setting provided between the non-inverting input terminal (+) of the second operational amplifier 14 and the ground; and 16 an inverter of the second operational amplifier 14. It is a ninth resistor for feedback provided between the input terminal (-) and the output terminal, and is connected to each resistor 12, 13, 15, 16 and the second operational amplifier 1.
4 constitutes a differential amplifier circuit, and the pressure sensor 1
The respective potentials of both output terminals 3a and 3b are input to the differential amplifier circuit, the difference between the two potentials is amplified, and a voltage signal based on the difference between the potentials is output.
１７，１８は第２オペアンプ１４の出力端子と
アースとの間に直列に設けられた分圧用第10，第
11抵抗、１９は非反転入力端子（＋）が抵抗１
７，１８の接続点に接続された第３オペアンプ、
２０は第３オペアンプ１９の反転入力端子（−）
とアースとの間に設けられたゲイン設定用第12抵
抗、２１は第３オペアンプ１９の反転入力端子
（−）と出力端子との間に設けられた帰還用第13
抵抗であり、第３オペアンプ１９および両抵抗２
０，２１により非反転増幅回路が構成され、前記
差動増幅回路の出力電圧が抵抗１７，１８により
分圧され、分圧された電圧が前記非反転増幅回路
により増幅されるようになつており、第３オペア
ンプ１９の出力端子に接続された信号出力端子２
２から、圧力センサ１に加えられた圧力に応じて
両出力端子３ａ，３ｂ間の電圧が増幅されて出力
される。 17 and 18 are 10th and 18th voltage dividing circuits which are connected in series between the output terminal of the second operational amplifier 14 and the ground.
11 resistor, 19 non-inverting input terminal (+) is resistor 1
a third operational amplifier connected to connection points 7 and 18;
20 is the inverting input terminal (-) of the third operational amplifier 19
21 is a 13th resistor for feedback provided between the inverting input terminal (-) and the output terminal of the third operational amplifier 19.
resistor, and the third operational amplifier 19 and both resistors 2
0 and 21 constitute a non-inverting amplifier circuit, the output voltage of the differential amplifier circuit is divided by resistors 17 and 18, and the divided voltage is amplified by the non-inverting amplifier circuit. , a signal output terminal 2 connected to the output terminal of the third operational amplifier 19
2, the voltage between both output terminals 3a and 3b is amplified and output according to the pressure applied to the pressure sensor 1.
つぎに、第４図において、第３図と同一記号は
同一のものを示し、２３は圧力センサ１のオフセ
ツト電圧零調整用第14抵抗であり、両端が圧力セ
ンサ１の抵抗素子１ｂの出力側の他端および抵抗
素子１ｄの出力端子３ｂに相当する一端に接続さ
れ、各抵抗素子１ａ〜１ｄの抵抗のばらつきによ
るセンサ１のオフセツト電圧が零になるような抵
抗値に設定されている。 Next, in FIG. 4, the same symbols as those in FIG. It is connected to the other end and one end corresponding to the output terminal 3b of the resistive element 1d, and is set to a resistance value such that the offset voltage of the sensor 1 due to resistance variations of the respective resistive elements 1a to 1d becomes zero.
なお、圧力センサ１の両入力端子２ａ，２ｂが
第１オペアンプ７の出力端子および反転入力端子
（−）に接続されている。 Note that both input terminals 2a and 2b of the pressure sensor 1 are connected to the output terminal and the inverting input terminal (-) of the first operational amplifier 7.
２４は非反転入力端子（＋）が圧力センサ１の
出力端子３ａに接続された第４オペアンプ、２５
は第４オペアンプ２４の反転入力端子（−）とア
ースとの間に設けられたゲイン設定用第15抵抗、
２６は第４オペアンプ２４の反転入力端子（−）
と出力端子との間に設けられた帰還用第16抵抗で
あり、第４オペアンプ２４と両抵抗２５，２６に
より非反転増幅回路が構成され、該増幅回路によ
り出力端子３ａの電位が増幅されて出力される。 24 is a fourth operational amplifier whose non-inverting input terminal (+) is connected to the output terminal 3a of the pressure sensor 1;
is the 15th resistor for gain setting provided between the inverting input terminal (-) of the fourth operational amplifier 24 and the ground,
26 is the inverting input terminal (-) of the fourth operational amplifier 24
The fourth operational amplifier 24 and both resistors 25 and 26 constitute a non-inverting amplifier circuit, and the potential of the output terminal 3a is amplified by the amplifier circuit. Output.
２７は非反転入力端子（＋）が圧力センサ１の
抵抗素子１ｄの一端に接続された第５オペアン
プ、２８は第５オペアンプ２７の反転入力端子
（−）と第４オペアンプ２４の出力端子との間に
設けられたゲイン設定用第17抵抗、２９は第５オ
ペアンプ２７の反転入力端子（−）と出力端子と
の間に設けられた帰還用第18抵抗であり、第５オ
ペアンプ２７及び両抵抗２８，２９により非反転
増幅回路が構成されるとともに、前記両非反転増
幅回路により差動増幅回路が構成され、第４、第
５オペアンプ２４，２７への圧力センサ１の両出
力端子３ａ，３ｂの電位の差が増幅されるように
なつており、第５オペアンプ２７の出力端子に接
続された信号出力端子３０から、圧力センサ１に
加えられた圧力に応じて生じる電圧が増幅されて
出力される。 27 is a fifth operational amplifier whose non-inverting input terminal (+) is connected to one end of the resistance element 1d of the pressure sensor 1; 28 is a connection between the inverting input terminal (-) of the fifth operational amplifier 27 and the output terminal of the fourth operational amplifier 24; The 17th resistor for gain setting provided between the 17th resistor and 29 is the 18th resistor for feedback provided between the inverting input terminal (-) and the output terminal of the 5th operational amplifier 27. 28 and 29 constitute a non-inverting amplifier circuit, and both non-inverting amplifier circuits constitute a differential amplifier circuit, both output terminals 3a and 3b of the pressure sensor 1 to the fourth and fifth operational amplifiers 24 and 27. The voltage generated in response to the pressure applied to the pressure sensor 1 is amplified and output from the signal output terminal 30 connected to the output terminal of the fifth operational amplifier 27. Ru.
ところが、前記した第３図、第４図に示す圧力
検出装置では、第５抵抗１１や第14抵抗２３の抵
抗値が適宜選定され、圧力センサ１の各抵抗素子
１ａ〜１ｄの抵抗値のばらつきにより生じるオフ
セツト電圧の過不足が調整されるが、一旦調整さ
れてしまうと抵抗１１，２３の抵抗値を再調整す
ることが困難であるため、周囲温度の変動による
各抵抗素子１ａ〜１ｄの抵抗値のばらつきにもと
づくオフセツト電圧のずれに対処することができ
ず、使用時の周囲温度によつて圧力の測定値がば
らつくという問題がある。
However, in the pressure detection device shown in FIGS. 3 and 4 described above, the resistance values of the fifth resistor 11 and the fourteenth resistor 23 are appropriately selected, and variations in the resistance values of the respective resistance elements 1a to 1d of the pressure sensor 1 are caused. The excess or deficiency of the offset voltage caused by this is adjusted, but once adjusted, it is difficult to readjust the resistance values of the resistors 11 and 23. It is not possible to deal with deviations in offset voltage due to variations in values, and there is a problem in that measured pressure values vary depending on the ambient temperature during use.
この考案は、前記の点に留意してなされ、周囲
温度の変動による圧力センサのオフセツト電圧の
ずれを自動的に補正して調整しようとするもので
あり、複数個のピエゾ抵抗素子のブリツジ回路構
成の圧力センサと、このセンサの出力信号を増幅
する増幅手段と、この増幅手段の出力信号を圧力
センサの零点調整用のオフセツト信号により補正
して測定信号を出力する信号補正手段と、圧力測
定の開始前の非測定時に測定信号を帰還積分して
該信号が零になるようにオフセツト信号を補正
し、圧力測定中に補正された前記オフセツト信号
を保持して前記信号補正手段に供給するオフセツ
ト保持手段とを備えた圧力検出装置である。
This invention was made with the above points in mind, and attempts to automatically correct and adjust deviations in the offset voltage of the pressure sensor due to fluctuations in ambient temperature, and uses a bridge circuit configuration of multiple piezoresistive elements. a pressure sensor, an amplification means for amplifying the output signal of the sensor, a signal correction means for correcting the output signal of the amplification means by an offset signal for adjusting the zero point of the pressure sensor and outputting a measurement signal; Offset holding that corrects the offset signal so that the signal becomes zero by feedback-integrating the measurement signal during non-measurement before starting, and holds the offset signal corrected during pressure measurement and supplies it to the signal correction means. It is a pressure detection device equipped with means.
したがつて、この考案によると、圧力測定の開
始前の非測定時には信号補正手段の測定信号の帰
還積分によりオフセツト保持手段のオフセツト信
号が更新され、周囲温度の変動による圧力センサ
の各ピエゾ抵抗素子の抵抗値のばらつきにもとづ
く圧力センサのオフセツト電圧のずれに応じて前
記オフセツト信号が補正され、測定出力の零点調
整が自動的に行なわれる。
Therefore, according to this invention, during non-measurement before the start of pressure measurement, the offset signal of the offset holding means is updated by feedback integration of the measurement signal of the signal correction means, and each piezoresistive element of the pressure sensor is corrected due to fluctuations in ambient temperature. The offset signal is corrected in accordance with the shift in the offset voltage of the pressure sensor due to variations in the resistance value of the pressure sensor, and the zero point adjustment of the measurement output is automatically performed.
そして、測定中は補正されたオフセツト信号に
より増幅手段の出力信号が補正されて測定信号が
形成されるため、周囲温度の変動による圧力セン
サのオフセツト電圧のずれを自動的に調整して測
定される。 During measurement, the output signal of the amplification means is corrected using the corrected offset signal to form the measurement signal, so the deviation in the offset voltage of the pressure sensor due to fluctuations in ambient temperature is automatically adjusted and measured. .
つぎに、この考案を、その１実施例を示した第
１図とともに詳細に説明する。
Next, this invention will be explained in detail with reference to FIG. 1 showing one embodiment thereof.
同図において、第３図と同一記号は同一のもの
もしくは相当するものを示し、第３図の抵抗１
０，１１が削除されて第１オペアンプ７の出力端
子が圧力センサ１の入力端子２ａに直接接続され
ており、３１，３２はそれぞれ一端が圧力センサ
１の出力端子３ａ，３ｂに接続された抵抗値の等
しいゲイン設定用第20，第21抵抗、３３は非反
転、反転入力端子（＋），（−）がそれぞれ第20，
第21抵抗３１，３２の他端に接続された第６オペ
アンプ、３４は第６オペアンプ３３の非反転入力
端子（＋）とアースとの間に設けられたゲイン設
定用第22抵抗、３５は第６オペアンプ３３の反転
入力端子（−）と出力端子との間に設けられた第
22抵抗３４と同一抵抗値の帰還用第23抵抗であ
り、各抵抗３１，３２，３４，３５および第６オ
ペアンプ３３により増幅手段である差動増幅回路
３６が構成されている。 In the figure, the same symbols as in Figure 3 indicate the same or equivalent items, and the resistor 1 in Figure 3
0 and 11 are deleted so that the output terminal of the first operational amplifier 7 is directly connected to the input terminal 2a of the pressure sensor 1, and 31 and 32 are resistors whose one ends are connected to the output terminals 3a and 3b of the pressure sensor 1, respectively. The 20th and 21st resistors for gain setting with equal values, 33 are non-inverting, and the inverting input terminals (+) and (-) are the 20th and 21st resistors, respectively.
A sixth operational amplifier connected to the other ends of the twenty-first resistors 31 and 32, 34 a twenty-second gain setting resistor provided between the non-inverting input terminal (+) of the sixth operational amplifier 33 and the ground, and 35 a sixth operational amplifier connected to the other ends of the twenty-first resistors 31 and 32; No. 6 provided between the inverting input terminal (-) and the output terminal of the operational amplifier 33.
A 23rd resistor for feedback has the same resistance value as the 22 resistor 34, and the resistors 31, 32, 34, 35 and the sixth operational amplifier 33 constitute a differential amplifier circuit 36 which is an amplifying means.
３７は一端が第６オペアンプ３３の出力端子に
接続されたゲイン設定用第24抵抗、３８は反転入
力端子（−）が第24抵抗３７の他端に接続された
第７オペアンプ、３９は第７オペアンプ３８の反
転入力端子（−）と出力端子との間に設けられた
第24抵抗３７、第７オペアンプ３８とともに信号
補正手段としての電圧増幅回路を構成する帰還用
第25抵抗、４０はドレインＤが第７オペアンプ３
８に出力端子に接続されゲートＧが保持指令手段
としての制御回路（図示せず）の出力端子４１に
接続され、圧力測定の開始直前に前記制御回路か
ら出力されるローレベルの保持指令信号により測
定期間中オフする電界効果トランジスタ（以下
FETという）、４２は反転入力端子（−）が第26
抵抗４３を介してFET４０のソースＳに接続さ
れ非反転入力端子（＋）がアースされた第８オペ
アンプ、４４は第８オペアンプ４２の反転入力端
子（−）と出力端子との間に設けられた時定数用
コンデンサ、４５はコンデンサ４４に並列接続さ
れた時定数用第27抵抗であり、FET４０、第８
オペアンプ４２、コンデンサ４４および両抵抗４
３，４５により積分回路構成のオフセツト保持手
段が形成され、この手段の出力端子である第８オ
ペアンプ４２の出力端子が第７オペアンプ３８の
非反転入力端子（＋）に接続され、前記電圧増幅
回路および積分回路により保持出力手段４６が構
成されている。 37 is a 24th resistor for gain setting whose one end is connected to the output terminal of the 6th operational amplifier 33, 38 is a 7th operational amplifier whose inverting input terminal (-) is connected to the other end of the 24th resistor 37, and 39 is a 7th operational amplifier. A 25th resistor for feedback constitutes a voltage amplification circuit as a signal correction means together with a 24th resistor 37 and a seventh operational amplifier 38 provided between the inverting input terminal (-) and the output terminal of the operational amplifier 38, and 40 is a drain D is the 7th operational amplifier 3
The gate G is connected to the output terminal 41 of a control circuit (not shown) serving as a holding command means, and a low level holding command signal outputted from the control circuit immediately before the start of pressure measurement A field effect transistor (hereinafter referred to as
FET), 42 has the inverting input terminal (-) as the 26th
An eighth operational amplifier 44 is connected to the source S of the FET 40 through a resistor 43 and has a non-inverting input terminal (+) grounded, and 44 is provided between the inverting input terminal (-) and the output terminal of the eighth operational amplifier 42. The time constant capacitor 45 is the 27th resistor for the time constant connected in parallel to the capacitor 44, and the FET 40 and the 8th
Operational amplifier 42, capacitor 44 and both resistors 4
3 and 45 form an offset holding means having an integral circuit configuration, and the output terminal of the eighth operational amplifier 42, which is the output terminal of this means, is connected to the non-inverting input terminal (+) of the seventh operational amplifier 38, and the voltage amplifying circuit is connected to the non-inverting input terminal (+) of the seventh operational amplifier 38. The holding output means 46 is constituted by the and integrating circuit.
なお、４７は第７オペアンプ３８の出力端子に
接続された保持出力手段４６の信号出力端子であ
る。 Note that 47 is a signal output terminal of the holding output means 46 connected to the output terminal of the seventh operational amplifier 38.
また、FET４０がオンしている間に第７オペ
アンプ３８の出力電圧が零に補正されるように、
前記積分回路の定数Ｔは圧力測定時間ｔ（約100〜
300msec）に対して十分長い3sec程度に設定され
る。 Also, while the FET 40 is on, the output voltage of the seventh operational amplifier 38 is corrected to zero.
The constant T of the integration circuit is determined by the pressure measurement time t (approximately 100~
300msec), it is set to about 3sec, which is sufficiently long.
そして、圧力測定の開始前の非測定時には、前
記したように前記制御回路から保持指令信号が出
力されないため、FET４０がオン状態に保持さ
れてオフセツト保持手段が信号補正手段の帰還
路、すなわち第７オペアンプ３８の出力端子と非
反転入力端子（＋）との間に接続され、このと
き、各抵抗素子１ａ〜１ｄの抵抗値のばらつきに
よる圧力センサ１のオフセツト電圧のずれが増幅
回路３６により増幅されて第７オペアンプ３８に
入力されても、測定信号としてのオフセツト電圧
を帰還積分したオフセツト保持手段のオフセツト
信号の電圧の第７オペアンプ３８への正帰還によ
り第７オペアンプ３８の出力端子が零に維持さ
れ、周囲温度の変動による各抵抗素子１ａ〜１ｄ
の抵抗値の変動により圧力センサ１の測定圧力が
変動する場合であつても、第７オペアンプ３８の
出力電圧が常に零に維持されて自動的に測定出力
の零点調整が行なわれる。 During non-measurement time before the start of pressure measurement, the holding command signal is not output from the control circuit as described above, so the FET 40 is held in the on state and the offset holding means is connected to the return path of the signal correction means, that is, the seventh It is connected between the output terminal of the operational amplifier 38 and the non-inverting input terminal (+), and at this time, the deviation in the offset voltage of the pressure sensor 1 due to variations in the resistance values of the respective resistance elements 1a to 1d is amplified by the amplifier circuit 36. Even if the voltage is input to the seventh operational amplifier 38, the output terminal of the seventh operational amplifier 38 is maintained at zero due to positive feedback of the voltage of the offset signal of the offset holding means, which is obtained by feedback-integrating the offset voltage as the measurement signal, to the seventh operational amplifier 38. and each resistance element 1a to 1d due to fluctuations in ambient temperature.
Even if the measured pressure of the pressure sensor 1 changes due to a change in the resistance value of the seventh operational amplifier 38, the output voltage of the seventh operational amplifier 38 is always maintained at zero, and the zero point of the measured output is automatically adjusted.
つぎに、圧力の測定を開始する場合、たとえば
血圧計であれば、血圧表示のリセツト操作等がト
リガとなつて前記制御回路より測定開始直前から
前記した圧力測定時間ｔに相当する時間FET４
０のゲートＧにローレベルの保持指令信号が出力
され、FET４０がオフし、FET４０がオフして
いる間はオフセツト保持手段に保持された最新の
オフセツト信号が基準信号として第７オペアンプ
３８に正帰還されることになり、圧力センサ１に
実際に圧力が加えられて圧力測定が行なわれるこ
とにより、圧力センサ１の両出力端子３ａ，３ｂ
間に生じる電圧が第６オペアンプ３３により増幅
されて第７オペアンプ３８の反転入力端子（−）
に入力され、第７オペアンプ３８により反転入力
端子（−）への増幅回路３６の出力信号と非反転
入力端子（＋）への前記積分回路からの基準信号
との差が増幅され、第６オペアンプ３３の出力信
号がオフセツト信号で補正されて測定信号として
出力端子４７から出力されることになる。 Next, when starting pressure measurement, for example, in the case of a blood pressure monitor, the reset operation of the blood pressure display etc. serves as a trigger, and the control circuit selects a time corresponding to the pressure measurement time t from just before the start of measurement FET4.
A low level hold command signal is output to the gate G of 0, the FET 40 is turned off, and while the FET 40 is turned off, the latest offset signal held in the offset holding means is positively fed back to the seventh operational amplifier 38 as a reference signal. When pressure is actually applied to the pressure sensor 1 and pressure measurement is performed, both output terminals 3a and 3b of the pressure sensor 1 are
The voltage generated between them is amplified by the sixth operational amplifier 33 and applied to the inverting input terminal (-) of the seventh operational amplifier 38.
The seventh operational amplifier 38 amplifies the difference between the output signal of the amplifier circuit 36 to the inverting input terminal (-) and the reference signal from the integrating circuit to the non-inverting input terminal (+). The output signal of 33 is corrected with the offset signal and outputted from the output terminal 47 as a measurement signal.
このとき、前記時定数Ｔが圧力測定時間ｔに比
べて十分大きく設定されているため、FET４０
がオフしている間、前記積分回路の出力電圧はほ
とんど変化することがない。 At this time, since the time constant T is set sufficiently larger than the pressure measurement time t, the FET40
While OFF, the output voltage of the integrating circuit hardly changes.
したがつて、圧力測定の開始直前におけるオフ
セツト保持手段のオフセツト信号にもとづく信号
補正により、従来のように圧力センサ１にオフセ
ツト電圧の零調整用の抵抗を設けて測定毎に調整
することなく、各抵抗素子１ａ〜１ｄの抵抗値の
ばらつきや周囲温度の変動によるオフセツト電圧
のずれが自動的に調整され、精度よく圧力測定を
行なうことが可能となる。 Therefore, by correcting the signal based on the offset signal of the offset holding means immediately before the start of pressure measurement, it is possible to adjust the offset voltage at each measurement time without having to provide a resistance for zero adjustment of the offset voltage in the pressure sensor 1 as in the past. Discrepancies in the offset voltage due to variations in the resistance values of the resistive elements 1a to 1d and variations in ambient temperature are automatically adjusted, making it possible to accurately measure pressure.
なお、保持出力手段４６のオフセツト保持手段
および信号補正手段は前記した構成に限らず、通
常の記憶回路および減算回路等からなるものであ
つてもよいことは勿論である。 It should be noted that the offset holding means and signal correction means of the holding output means 46 are not limited to the above-mentioned configuration, but may of course be constructed from ordinary storage circuits, subtraction circuits, and the like.
以上のように、この考案の圧力検出装置による
と、圧力測定の開始前の非測定時には信号補正手
段の測定信号の帰還積分によりオフセツト保持手
段のオフセツト信号が更新され、周囲温度の変動
による圧力センサ１の各ピエゾ抵抗素子１ａ〜１
ｄの抵抗値のばらつきにもとづく圧力センサ１の
オフセツト電圧のずれに応じて前記オフセツト信
号が補正され、測定出力の零点調整が自動的に行
なわれ、測定中は補正されたオフセツト信号によ
り増幅手段の出力信号が補正されて測定信号が形
成されるため、従来のように圧力センサ１にオフ
セツト電圧の零調整用抵抗や温度補償用抵抗等を
設けることなく、圧力センサ１のオフセツト電圧
のずれの調整を自動的に行なうことができ、圧力
センサ１の各抵抗素子１ａ〜１ｄの抵抗値が周囲
温度により変動した場合であつても、この変動に
伴うオフセツト電圧のずれを自動的に補正するこ
とができ、簡単な構成により煩雑なオフセツト調
整作業を省いて精度よい圧力測定を行なうことが
可能となり、その効果は顕著である。
As described above, according to the pressure detection device of this invention, the offset signal of the offset holding means is updated by feedback integration of the measurement signal of the signal correction means during non-measurement time before the start of pressure measurement, and the offset signal of the offset holding means is updated by the feedback integration of the measurement signal of the signal correction means. Each piezoresistive element 1a to 1 of 1
The offset signal is corrected in accordance with the deviation in the offset voltage of the pressure sensor 1 based on the variation in the resistance value of d, and the zero point adjustment of the measurement output is automatically performed. Since the output signal is corrected to form the measurement signal, it is possible to adjust the deviation in the offset voltage of the pressure sensor 1 without providing a resistance for zero adjustment of the offset voltage, a resistance for temperature compensation, etc. in the pressure sensor 1 as in the conventional case. Even if the resistance values of the resistance elements 1a to 1d of the pressure sensor 1 fluctuate due to the ambient temperature, the offset voltage deviation due to this fluctuation can be automatically corrected. The simple structure makes it possible to perform accurate pressure measurement without complicated offset adjustment work, and the effect is remarkable.
第１図はこの考案の圧力検出装置の１実施例の
結線図、第２図は通常の圧力センサの等価回路
図、第３図および第４図はそれぞれ従来の圧力検
出装置の結線図である。
１……圧力センサ、１ａ〜１ｄ……ピエゾ抵抗
素子、９……定電流回路、３６……差動増幅回
路、４６……保持出力手段。
Figure 1 is a wiring diagram of one embodiment of the pressure detection device of this invention, Figure 2 is an equivalent circuit diagram of a normal pressure sensor, and Figures 3 and 4 are wiring diagrams of conventional pressure detection devices, respectively. . DESCRIPTION OF SYMBOLS 1... Pressure sensor, 1a-1d... Piezo resistance element, 9... Constant current circuit, 36... Differential amplifier circuit, 46... Holding output means.
Claims (1)
圧力センサと、 前記圧力センサの出力信号を増幅する増幅手段
と、 前記増幅手段の出力信号を前記圧力センサの零
点調整用のオフセツト信号により補正して測定信
号を出力する信号補正手段と、 圧力測定の開始前の非測定時に前記測定信号を
帰還積分して該信号が零になるように前記オフセ
ツト信号を補正し、圧力測定中に補正された前記
オフセツト信号を保持して前記信号補正手段に供
給するオフセツト保持手段と を備えた圧力検出装置。[Claims for Utility Model Registration] A pressure sensor having a bridge circuit configuration of a plurality of piezoresistive elements, an amplifying means for amplifying an output signal of the pressure sensor, and an output signal of the amplifying means for adjusting the zero point of the pressure sensor. signal correction means for correcting the measurement signal using an offset signal of the pressure measurement signal and outputting the measurement signal; A pressure detection device comprising: offset holding means for holding the offset signal corrected during measurement and supplying it to the signal correction means.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1985111168U JPH0431535Y2 (en) | 1985-07-20 | 1985-07-20 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1985111168U JPH0431535Y2 (en) | 1985-07-20 | 1985-07-20 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6220305U JPS6220305U (en) | 1987-02-06 |
| JPH0431535Y2 true JPH0431535Y2 (en) | 1992-07-29 |
Family
ID=30990839
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1985111168U Expired JPH0431535Y2 (en) | 1985-07-20 | 1985-07-20 |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0431535Y2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2019219332A (en) * | 2018-06-21 | 2019-12-26 | 株式会社マコメ研究所 | Induction coil sensor |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58140604A (en) * | 1982-02-17 | 1983-08-20 | Hitachi Ltd | Temperature compensating circuit for semiconductor strain gage |
| JPS59122923A (en) * | 1982-12-28 | 1984-07-16 | Toshiba Corp | Pressure transmitting device |
-
1985
- 1985-07-20 JP JP1985111168U patent/JPH0431535Y2/ja not_active Expired
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58140604A (en) * | 1982-02-17 | 1983-08-20 | Hitachi Ltd | Temperature compensating circuit for semiconductor strain gage |
| JPS59122923A (en) * | 1982-12-28 | 1984-07-16 | Toshiba Corp | Pressure transmitting device |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6220305U (en) | 1987-02-06 |
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