JPS6129730B2 - - Google Patents
Info
- Publication number
- JPS6129730B2 JPS6129730B2 JP56004175A JP417581A JPS6129730B2 JP S6129730 B2 JPS6129730 B2 JP S6129730B2 JP 56004175 A JP56004175 A JP 56004175A JP 417581 A JP417581 A JP 417581A JP S6129730 B2 JPS6129730 B2 JP S6129730B2
- Authority
- JP
- Japan
- Prior art keywords
- light
- detection circuit
- pulse
- circuit
- receiving element
- 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
Landscapes
- Measuring Pulse, Heart Rate, Blood Pressure Or Blood Flow (AREA)
Description
【発明の詳細な説明】 本発明は脈拍検出回路に関する。[Detailed description of the invention] The present invention relates to a pulse detection circuit.
従来、脈拍を検出する方法としては、例えば指
や耳などの身体の一部分にLEDの如き発光素子
から発せられた光線を照射し、その反射光または
透過光をフオトセルの如き受光素子を用いて電気
信号に変換することにより、その際の血液の容量
変化を脈拍信号として取り出し、脈拍を検出する
方法が用いられている。第１図はこの従来の脈拍
検出回路のブロツク図を示すものである。図にお
いて１はLEDの如き発光素子、R1は抵抗、２は
指Ｆからの反射光を受光して電気信号に変換する
フオトセルの如き受光素子、３は受光素子２で生
じた光電流を電圧に変換して増幅する検出回路、
４はノイズを除去するためのフイルタ、５は増幅
回路、６は予め設定された閾値と増幅回路５の出
力を比較して脈拍をパルス信号に変換するコンパ
レータ（またはシユミツトトリガ回路）である。 Conventionally, the method of detecting pulse is to irradiate a part of the body such as a finger or ear with a light beam emitted from a light emitting element such as an LED, and convert the reflected or transmitted light into electricity using a light receiving element such as a photocell. A method is used in which the blood volume change at that time is extracted as a pulse signal by converting it into a signal, and the pulse is detected. FIG. 1 shows a block diagram of this conventional pulse detection circuit. In the figure, 1 is a light emitting element such as an LED, R1 is a resistor, 2 is a light receiving element such as a photocell that receives reflected light from the finger F and converts it into an electrical signal, and 3 is a voltage that converts the photocurrent generated in the light receiving element 2 into a voltage. a detection circuit that converts and amplifies the
4 is a filter for removing noise, 5 is an amplifier circuit, and 6 is a comparator (or Schmitt trigger circuit) that compares the output of the amplifier circuit 5 with a preset threshold value and converts the pulse into a pulse signal.
しかしその動作を説明すると、発光素子１より
照射された光線は指Ｆの皮膚表面で反射され、受
光素子２で受光される。この反射光には血液の容
量変化に伴う皮膚表面の微動による脈拍信号が含
まれており、受光素子２はその変化を電気信号に
変換する。また一般に半導体の受光素子はPN接
合部の逆電流を出力するため、受光素子２の出
力、すなわち光電流は検出回路３によつて電流か
ら電圧に変換され、フイルタ４によつてノイズを
除去された後、増幅回路５により十分なレベルに
まで増幅され、コンパレータ６に加えられる。コ
ンパレータ６では予め適当なレベルに設定された
閾値と増幅回路５の出力とを比較し、後続するデ
イジタル素子等で構成される信号処理回路（図示
せず）での取り扱いを容易にするために脈拍信号
をパルス信号に変換する。 However, to explain its operation, the light beam emitted from the light emitting element 1 is reflected by the skin surface of the finger F, and is received by the light receiving element 2. This reflected light contains a pulse signal caused by minute movements on the skin surface due to changes in blood capacitance, and the light receiving element 2 converts the changes into electrical signals. Furthermore, since a semiconductor photodetector generally outputs a reverse current at the PN junction, the output of the photodetector 2, that is, the photocurrent, is converted from current to voltage by the detection circuit 3, and noise is removed by the filter 4. After that, the signal is amplified to a sufficient level by the amplifier circuit 5 and applied to the comparator 6. The comparator 6 compares the output of the amplifier circuit 5 with a threshold set in advance to an appropriate level, and calculates the pulse rate to facilitate handling in a subsequent signal processing circuit (not shown) consisting of digital elements, etc. Convert the signal into a pulse signal.
以上が従来の脈拍検出回路の構成およびその動
作の概要である。ところで、一般に身体表面によ
つて得られる脈波は第２図に示す如く環境温度の
低下と共にその振幅が弱まる性質がある。しかし
て上述した従来の脈拍検出回路においては、その
一部を構成する検出回路３、増幅回路５のゲイン
が一定であるため、第２図の如く環境温度の低下
に伴つて指Ｆ表面の脈波振幅が小さくなると、脈
拍の検出が困難となり、極端な場合には増幅回路
５の出力がコンパレータ６の閾値に達しないため
パルス信号に変換できなくなることもあつた。 The above is an overview of the configuration and operation of the conventional pulse detection circuit. By the way, pulse waves obtained from the body surface generally have a property that the amplitude weakens as the environmental temperature decreases, as shown in FIG. However, in the above-described conventional pulse detection circuit, since the gains of the detection circuit 3 and the amplifier circuit 5 that constitute a part of the circuit are constant, the pulse on the surface of the finger F increases as the environmental temperature decreases as shown in FIG. As the wave amplitude becomes smaller, it becomes difficult to detect pulses, and in extreme cases, the output of the amplifier circuit 5 may not reach the threshold of the comparator 6, making it impossible to convert it into a pulse signal.
本発明は上記の点に鑑み提案されたものであ
り、環境温度が低下すると回路のゲインを上げて
脈拍振幅の減少を相殺し、環境温度の変化に拘わ
らず一定の精度で脈拍を検出することのできる脈
拍検出回路を提供することを目的とするものであ
る。 The present invention has been proposed in view of the above points, and it is an object of the present invention to increase the gain of the circuit when the environmental temperature decreases to offset the decrease in pulse amplitude, and to detect the pulse with constant accuracy regardless of changes in the environmental temperature. The purpose of this invention is to provide a pulse detection circuit that can perform the following steps.
以下、図面に従つて本発明の実施例を詳述す
る。 Embodiments of the present invention will be described in detail below with reference to the drawings.
第３図は本発明の一実施例を示したものであ
り、受光素子２と検出回路３′のみを示してお
り、第１図における受光素子２、検出回路３の部
分を第３図のように置き換えたものが全体の構成
となる。 FIG. 3 shows an embodiment of the present invention, showing only the light receiving element 2 and the detection circuit 3', and the parts of the light receiving element 2 and the detection circuit 3 in FIG. 1 are replaced as shown in FIG. The overall configuration is what is replaced with .
第３図において検出回路３′はOPアンプA1か
ら構成され、受光素子２に生じた電流を電圧に変
換する電流−電圧変換器を形成している。また、
OPアンプA1の帰還抵抗は負特性サーミスタＲ
１，Ｒ2と正特性サーミスタＲ3とのＴ字型回
路で構成されている。 In FIG. 3, the detection circuit 3' is composed of an OP amplifier A1 , forming a current-voltage converter that converts the current generated in the light receiving element 2 into a voltage. Also,
The feedback resistance of OP amplifier A1 is a negative characteristic thermistor R.
1 , R2 and a positive temperature coefficient thermistor R3 .
検出回路３′のゲインＧはサーミスタＲ1，Ｒ
2，Ｒ3の抵抗値を同符号で表わすことにする
と、次式
Ｇ＝Ｒ1＋Ｒ2＋Ｒ１・Ｒ２／Ｒ３ ……(1)
のようになり、受光素子２に生じた電流をＧ倍し
た電圧が検出回路３′の出力端に現れることにな
る。 The gain G of the detection circuit 3' is thermistor R 1 , R
If the resistance values of 2 and R 3 are expressed with the same sign, the following equation becomes G=R 1 +R 2 +R 1・R 2 /R 3 (1), and the current generated in the light receiving element 2 is A voltage multiplied by G will appear at the output terminal of the detection circuit 3'.
しかして、環境度が低下すると受光素子２の電
流に含まれる脈波成分の振幅が小さくなるが、こ
れと同時に負特性サーミスタＲ1，Ｒ2の抵抗
値が大、正特性サーミスタＲ3の抵抗値が小と
なり、前記(1)式のゲインＧが大きくなり、各定数
を適切に設定しておくことにより脈波振幅の低下
を打ち消すようにすることができる。 As the environmental level decreases, the amplitude of the pulse wave component included in the current of the light receiving element 2 decreases, but at the same time, the resistance values of the negative characteristic thermistors R 1 and R 2 increase, and the resistance of the positive characteristic thermistor R 3 decreases. The value becomes small, and the gain G in equation (1) becomes large. By appropriately setting each constant, it is possible to cancel out the decrease in the pulse wave amplitude.
なお、検出回路を構成する電流−電圧変換器に
おいては、帰還抵抗には一般的に高抵抗を用いる
ことが好ましい反面、単一のサーミスタでは余り
大きな抵抗値を得ることができないものである
が、本発明のようにサーミスタでＴ字型回路を構
成することにより、大きな抵抗値を得られるよう
にすると同時に、環境温度の低下に対するゲイン
の増加率も大きくすることができる。すなわち、
前記(1)式はそのまま帰還抵抗の値を示しており、
この式からも明らかなように抵抗値を充分に大き
くでき、かつ環境温度に対する変化率も大きくす
ることができる。 In addition, in the current-voltage converter that constitutes the detection circuit, it is generally preferable to use a high resistance as the feedback resistor, but on the other hand, it is not possible to obtain a very large resistance value with a single thermistor. By configuring a T-shaped circuit using thermistors as in the present invention, it is possible to obtain a large resistance value, and at the same time, it is possible to increase the rate of increase in gain with respect to a decrease in environmental temperature. That is,
The above formula (1) directly shows the value of the feedback resistance,
As is clear from this equation, the resistance value can be sufficiently increased, and the rate of change with respect to the environmental temperature can also be increased.
以上のように本発明の脈拍検出回路によれば、
環境温度が低下すると回路のゲインを高めるよう
にして環境温度の低下に起因する検出脈波の減少
分を相殺するようにきたから、検出信号をコンパ
レータまたはシユミツトトリガ回路等でパルス信
号に変換する際にレベル不足で動作が不能になる
おそれが皆無であり、また回路の必要ゲインを脈
波の最小値に適合させて設定する必要がないた
め、脈波中のノイズ成分を不必要に増幅すること
がなくＳ／Ｎ比が良くなる効果がある。 As described above, according to the pulse detection circuit of the present invention,
When the environmental temperature decreases, the gain of the circuit is increased to offset the decrease in the detected pulse wave due to the decrease in the environmental temperature. There is no risk of operation being disabled due to insufficient level, and there is no need to set the required gain of the circuit to match the minimum value of the pulse wave, so there is no need to amplify noise components in the pulse wave unnecessarily. This has the effect of improving the S/N ratio.
また、電流−電圧変換器としての検出回路を構
成するOPアンプの帰還抵抗をサーミスタによる
Ｔ字型回路としているので、帰還抵抗を大きくし
て変換のゲインを大とでき、更に環境温度に対す
るゲインの変化幅も大きくできる効果がある。 In addition, since the feedback resistance of the OP amplifier that constitutes the detection circuit as a current-voltage converter is a T-shaped circuit using a thermistor, it is possible to increase the conversion gain by increasing the feedback resistance, and furthermore, it is possible to increase the conversion gain by increasing the feedback resistance. This has the effect of increasing the range of change.
第１図は従来の脈拍検出回路のブロツク図、第
２図は環境温度と脈波振幅との関係を表わすグラ
フ、第３図は本発明の一実施例を示す回路図であ
る。
１……発光素子、２……受光素子、３，３′…
…検出回路、４……フイルタ、５……増幅回路、
６……コンパレータ、Ｆ……指、R1……抵抗、
A1……OPアンプ、Ｒ1，Ｒ2……負特性サー
ミスタ、Ｒ3……正特性サーミスタ。
FIG. 1 is a block diagram of a conventional pulse detection circuit, FIG. 2 is a graph showing the relationship between environmental temperature and pulse wave amplitude, and FIG. 3 is a circuit diagram showing an embodiment of the present invention. 1... Light emitting element, 2... Light receiving element, 3, 3'...
...Detection circuit, 4...Filter, 5...Amplification circuit,
6...Comparator, F...Finger, R1 ...Resistance,
A1 ...OP amplifier, R1 , R2 ...Negative characteristic thermistor, R3 ...Positive characteristic thermistor.
Claims (1)
子から照射された光線による身体の一部からの反
射光または透過光を受光して受光信号となし、該
受光信号を脈波信号に変換して脈拍を検出する回
転において、前記受光素子の出力側にオペアンプ
により構成される検出回路を設け、前記オペアン
プの帰還抵抗として、出力端子と反転入力端子間
に直列接続された一対の負特性サーミスタと、該
負特性サーミスタ相互の接続点に一端が接続され
かつ他端が接地される正特性サーミスタとを有し
てなり、環境温度の低下に伴い前記検出回路のゲ
インを増加せしめることを特徴とする脈拍検出回
路。1 comprises a light-emitting element and a light-receiving element, receives reflected light or transmitted light from a part of the body due to the light beam irradiated from the light-emitting element, converts the received light signal into a pulse wave signal, and detects the pulse wave signal. In the rotation for detecting the rotation, a detection circuit composed of an operational amplifier is provided on the output side of the light receiving element, and a pair of negative characteristic thermistors connected in series between the output terminal and the inverting input terminal are used as feedback resistors of the operational amplifier. and a positive characteristic thermistor whose one end is connected to a connection point between the negative characteristic thermistors and whose other end is grounded, and the pulse rate detection is characterized in that the gain of the detection circuit is increased as the environmental temperature decreases. circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP417581A JPS57117830A (en) | 1981-01-14 | 1981-01-14 | Pulse detecting circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP417581A JPS57117830A (en) | 1981-01-14 | 1981-01-14 | Pulse detecting circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57117830A JPS57117830A (en) | 1982-07-22 |
| JPS6129730B2 true JPS6129730B2 (en) | 1986-07-09 |
Family
ID=11577374
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP417581A Granted JPS57117830A (en) | 1981-01-14 | 1981-01-14 | Pulse detecting circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS57117830A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8655436B2 (en) | 2005-09-27 | 2014-02-18 | Citizen Holdings Co., Ltd. | Heart rate meter and heart beat detecting method |
| US8897864B2 (en) | 2005-09-15 | 2014-11-25 | Citizen Holdings Co., Ltd. | Heart rate meter and method for removing noise of heart beat waveform |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5997209A (en) * | 1982-11-25 | 1984-06-05 | Mitsubishi Electric Corp | Ic for operational amplification |
| JPS61162932A (en) * | 1985-01-11 | 1986-07-23 | 稲場 文男 | Brain wave measuring apparatus |
| JPS6451314U (en) * | 1987-09-24 | 1989-03-30 | ||
| JPS6454413U (en) * | 1987-09-30 | 1989-04-04 | ||
| JP5570475B2 (en) * | 2011-07-05 | 2014-08-13 | 三菱電機株式会社 | Radiation monitor |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5283493U (en) * | 1975-12-18 | 1977-06-22 |
-
1981
- 1981-01-14 JP JP417581A patent/JPS57117830A/en active Granted
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8897864B2 (en) | 2005-09-15 | 2014-11-25 | Citizen Holdings Co., Ltd. | Heart rate meter and method for removing noise of heart beat waveform |
| US8655436B2 (en) | 2005-09-27 | 2014-02-18 | Citizen Holdings Co., Ltd. | Heart rate meter and heart beat detecting method |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57117830A (en) | 1982-07-22 |
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