CN104887244B - A kind of LED drives human body signal acquisition method - Google Patents
A kind of LED drives human body signal acquisition method Download PDFInfo
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- CN104887244B CN104887244B CN201510190534.XA CN201510190534A CN104887244B CN 104887244 B CN104887244 B CN 104887244B CN 201510190534 A CN201510190534 A CN 201510190534A CN 104887244 B CN104887244 B CN 104887244B
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Abstract
A kind of LED drives human body signal acquisition method, and it includes：One 3 wavelength LED of probe is driven with the sine-wave current signal of different frequencies, allow itself and meanwhile it is luminous, the frequency spectrum of LED luminous signals is single, photodiode receives induced signal, the direct current signal in reception signal is removed by 1uf electric capacity, current signal is transformed to by voltage signal as transreactance amplifier using the amplifier of high CMRR Low-bias Current, then elimination common-mode signal is gone by difference amplifier again, then the interference signal beyond useful signal is got rid of by narrow-band pass filter again, then signal carries out shaping by accurate all-wave shaping circuit to signal, translate the signals into finally by DC filtering and sampled for direct current signal to AD.The present invention, so greatly improving the ability of systematic sampling process signal, due to strong antijamming capability, so LED driving current greatly reduces, improves LED service life by being direct current signal due to what is finally sampled.
Description
Technical field
The present invention relates to medical detection field, more particularly to a kind of LED drivings human body signal acquisition method.
Background technology
Near infrared tissue blood oxygen parameter non-destructive testing technology (near infrared spectroscopy, NIRS) is nearly 20
The physio-parameter detection technology gradually risen over year, its core Testing index is tissue oxygenation saturation (tissue oxygen
Index, TOI) and tissue hemoglobin concentration index (tissue hemoglobin index, THI).Near infrared tissue blood oxygen
Parameter non-destructive monitoring instrument (hereinafter referred to as BOLD contrast) is based on NIRS technologies, and the light of three kinds of different wave lengths is passed through into constant current square wave
Luminous mode is incided in tested tissue, the intensity of emergent light is measured by photodiode, then by Current Voltage
(IV) conversion circuit, signal amplification circuit, AD samplings and signal transacting obtain absorption of the tissue to light, then by a series of
Solution process, finally give tested tissue oxygen saturation and hemoglobin concentration index.
At present, a kind of BOLD contrast in the prior art be present, it uses different wave length to determine frequency square wave constant current and lighted, different
Wavelength LED is alternately luminous, and the scheme of photodiode reception signal synchronized sampling.The BOLD contrast includes 4 passages and contains 12
Individual LED and 8 pin pipes, LED constant current driving frequency is 500hz, and single individual pin pipes input signal 125hz, this kind of BOLD contrast is adopted
All sampled with bright level and black level to eliminate dark current interference, sample rate 2.5khz, the sample rate of system is 20khz, light
Electric diode connection cables use the Double-strand transmission with shielding, and preamplifier has sufficiently high common-mode rejection ratio, and uses
The mode of differential amplification.
As shown in figure 1, Fig. 1 is the impulse response schematic diagram of photodetector, due to when detecting the blood oxygen of deeper tissue
Wait weaker for the signal of reception, small to arrive 1nA, now in order to ensure sampling precision, system maximum equivalent gain is arranged to 300M Europe
Nurse, and due to the impossible complete equipilibrium of cable transmission, so 50hz power frequency component waveforms are measured in AD sampling ends, still, when it
Peak-to-peak value has reached nearly 100mv, constrains the precision and stability of systematic sampling.Due to the responding ability of hardware and the place of system
Reason ability will meet the requirement of sampling precision simultaneously, result in the frequency and 50hz power frequency components and its harmonic frequency of useful signal
It is close, and be difficult to be removed power frequency interference signals not interfere with the collection of useful signal simultaneously, so only by hardware filtering
Can be by adding low pass filter to filter out High-frequency Interference；Although moreover, employ high cmrr (Common Mode
Rejection Ratio, abbreviation CMRR) transreactance amplifier of the amplifier as front end, but parasitic capacitance due to circuit board or
It is the imbalance of PCB layout and transmission cable, space others electromagnetic interference signal is inevitably introduced into measuring system, institute
So that in summary, this kind of BOLD contrast has the disadvantage that：
1st, to 50hz power frequency coupled signal poor anti jamming capabilities；
2nd, due to the frequecy characteristic of useful signal, make the cut-off frequency of low-pass filter circuit higher, cause to other low frequencies
Interference signal rejection ability is poor；
3rd, LED operation is made to reduce LED service life under higher driving current in order to improve signal to noise ratio；
4th, LED drive circuit and PIN pipes receiving circuit cause the wire design of probe to require high using non-isolated scheme, enter
And cause line partially hard partially thick.
Therefore, for above-mentioned technical problem, it is necessary to a kind of new LED drivings human body signal acquisition method is provided, with gram
Take drawbacks described above.
The content of the invention
In view of this, it is an object of the invention to provide a kind of LED to drive human body signal acquisition method, and this method uses
The Sine Modulated of LED drive current signal and the DC converting of sinusoidal signal sample, because what is finally sampled is direct current signal, institute
To greatly improve the ability of systematic sampling process signal, due to strong antijamming capability, so LED driving greatly reduces
Electric current, improve LED service life.
To achieve the above object, the present invention provides following technical scheme：
A kind of LED drives human body signal acquisition method, and this method uses the Sine Modulated and sine of LED drive current signal
The DC converting sampling of signal, specifically comprises the following steps：
S1：One LED drive circuit is provided, 3 wavelength LED of probe are believed with the sine-wave current of different frequencies
Number driving, allow itself and meanwhile it is luminous, realize that the sine DC bias modulation of LED drive signal drives；
S2：One photodiode receiving circuit is provided, induced signal is received by photodiode, will be connect by luf electric capacity
Direct current signal in the collection of letters number removes；
S3：Current signal is transformed to by voltage letter as transreactance amplifier using the amplifier of high CMRR Low-bias Current
Number；
S4：Go to eliminate common-mode signal by difference amplifier；
S5：The interference signal beyond useful signal is removed by narrow-band pass filter；
S6：Signal carries out shaping by accurate all-wave shaping circuit to signal；
S7：Translated the signals into by DC filtering and sampled for direct current signal to AD.
Preferably, in above-mentioned LED drives human body signal acquisition method, in the step S 1, the frequency of LED luminous signals
Compose single.
Preferably, in above-mentioned LED drives human body signal acquisition method, in the S5, the selection of useful signal frequency is reached
Any one frequency between 13k~16khz.
Preferably, in above-mentioned LED drives human body signal acquisition method, in the S5 ,-the 3db of passage bandwidth is only
For 80hz, the decay of frequency where useful signal is less than -0.01db.
Preferably, in above-mentioned LED drives human body signal acquisition method, LED drive circuit receives electricity with photodiode
Road is electrically isolated completely to.
Compared with prior art, the beneficial effects of the invention are as follows：
(1) ability for being direct current signal, greatly improving systematic sampling process signal finally sampled；
(2) strong antijamming capability, LED driving current greatly reduces, improves LED service life；
(3) taken place frequently light using point, can use narrow-band pass filter, not only by 50HZ signal removal, and by before
The design defect of low pass filter also compensate for；
(4) LED drive circuit is electrically isolated completely to photodiode receiving circuit, enormously simplify setting for probe cable
Meter, also allow for the practical design of probe.
Brief description of the drawings
Fig. 1 is the impulse response schematic diagram of photodetector.
Fig. 2 is the signal that LED of the present invention drives the Sine Modulated of LED drive current signal in human body signal acquisition method
Figure；
Fig. 3 is the schematic flow sheet that LED of the present invention drives human body signal acquisition method；
Fig. 4 is the signal that LED of the present invention drives sine wave LED current drive signal waveform in human body signal acquisition method
Figure；
Fig. 5 is the schematic diagram that LED of the present invention drives IV conversion circuits in human body signal acquisition method；
Fig. 6 is the schematic diagram that LED of the present invention drives narrow-band pass filter in human body signal acquisition method；
Fig. 7 is the schematic diagram that LED of the present invention drives all-wave shaping in human body signal acquisition method.
Embodiment
The invention discloses a kind of LED to drive human body signal acquisition method, and this method is using LED drive current signal just
String is modulated to be sampled with the DC converting of sinusoidal signal, because what is finally sampled is direct current signal, is adopted so greatly improving system
The ability of sample process signal, due to strong antijamming capability, so LED driving current greatly reduces, improve LED use
Life-span.
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is retouched in detail
State, it is clear that described embodiment is only part of the embodiment of the present invention, rather than whole embodiments.Based on the present invention
In embodiment, the every other implementation that those of ordinary skill in the art are obtained on the premise of creative work is not made
Example, belongs to the scope of protection of the invention.
As shown in Fig. 2 a kind of LED drivings human body signal acquisition method disclosed by the invention, this method is using LED driving electricity
The DC converting of the Sine Modulated and sinusoidal signal that flow signal samples.
Specifically it is expressed as follows：
The sine DC bias modulation driving of LED drive signal is exactly to design a circuit by the 3 wavelength LED that pop one's head in
It is allowed to light simultaneously with the driving of the sine-wave current signal of different frequencies.
W1=sin (a1)
W2=sin (a2)
W3=sin (a3)
As shown in Figures 3 to 5, LED illumination mode lighted different with former rectangle, the frequency spectrum list of luminous signal
One, it is easy to the processing of follow-up signal；When signal receives induced signal after tissue by photodiode, pass through
1uf electric capacity, the direct current signal in reception signal is removed；Amplifier using high CMRR Low-bias Current is amplified as mutual resistance
Current signal is transformed to voltage signal by device；Then elimination common-mode signal is gone by difference amplifier again；Then Fig. 6 institutes are passed through again
The narrow-band pass filter shown gets rid of the interference signal beyond useful signal, reach useful signal frequency selection 13k~
Any one frequency between the 16khz, then -3db of passage bandwidth is only 80hz, the decay of frequency where useful signal
It is so very high for the rejection ability of interference signal less than -0.01db；Then as shown in fig. 7, signal is whole by accurate all-wave
Shape circuit carries out shaping to signal, translates the signals into finally by DC filtering and is sampled for direct current signal to AD.
In above-mentioned LED drives human body signal acquisition method, LED drive circuit is completely electric with photodiode receiving circuit
Air bound from.
Compared with prior art, the beneficial effects of the invention are as follows：
(1) ability for being direct current signal, greatly improving systematic sampling process signal finally sampled；
(2) strong antijamming capability, LED driving current greatly reduces, improves LED service life；
(3) taken place frequently light using point, can use narrow-band pass filter, not only by 50HZ signal removal, and by before
The design defect of low pass filter also compensate for；
(4) LED drive circuit is electrically isolated completely to photodiode receiving circuit, enormously simplify setting for probe cable
Meter, also allow for the practical design of probe.
It is obvious to a person skilled in the art that the invention is not restricted to the details of above-mentioned one exemplary embodiment, Er Qie
In the case of without departing substantially from spirit or essential attributes of the invention, the present invention can be realized in other specific forms.Therefore, no matter
From the point of view of which point, embodiment all should be regarded as exemplary, and be nonrestrictive, the scope of the present invention is by appended power
Profit requires rather than described above limits, it is intended that all in the implication and scope of the equivalency of claim by falling
Change is included in the present invention.Any reference in claim should not be considered as to the involved claim of limitation.
Moreover, it will be appreciated that although the present specification is described in terms of embodiments, not each embodiment is only wrapped
Containing an independent technical scheme, this narrating mode of specification is only that those skilled in the art should for clarity
Using specification as an entirety, the technical solutions in the various embodiments may also be suitably combined, forms those skilled in the art
It is appreciated that other embodiment.
Claims (3)
1. a kind of LED drives human body signal acquisition method, it is characterised in that：This method uses the sine of LED drive current signal
Modulation and the DC converting of sinusoidal signal sample, and specifically comprise the following steps：
S1：One LED drive circuit is provided, 3 wavelength LED of probe are driven with the sine-wave current signal of different frequencies
It is dynamic, allow itself and meanwhile it is luminous, realize that the sine DC bias modulation of LED drive signal drives；
S2：One photodiode receiving circuit is provided, induced signal is received by photodiode, will receive and believe by luf electric capacity
Direct current signal in number removes；
S3：Current signal is transformed to by voltage signal as transreactance amplifier using the amplifier of high CMRR Low-bias Current；
S4：Go to eliminate common-mode signal by difference amplifier；
S5：The interference signal beyond useful signal is removed by narrow-band pass filter, useful signal frequency is selected in 13k-
Any one frequency between 16khz ,-the 3db of passage bandwidth is only 80hz, and the decay of frequency is small where useful signal
In -0.01db；
S6：Signal carries out shaping by accurate all-wave shaping circuit to signal；
S7：Translated the signals into by DC filtering and sampled for direct current signal to AD.
2. LED according to claim 1 drives human body signal acquisition method, it is characterised in that：In the step S1, LED
The frequency spectrum of luminous signal is single.
3. LED according to claim 1 drives human body signal acquisition method, it is characterised in that：The LED drive circuit with
Photodiode receiving circuit is electrically isolated completely to.
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| CN201510190534.XA CN104887244B (en) | 2015-04-21 | 2015-04-21 | A kind of LED drives human body signal acquisition method |
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| CN104887244B true CN104887244B (en) | 2018-03-02 |
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| CN109222922A (en) * | 2018-10-17 | 2019-01-18 | 南京沃福曼医疗科技有限公司 | A method of improving the anti-level interference of OCT equipment sensitive circuit |
| CN113162724A (en) * | 2020-01-23 | 2021-07-23 | ***通信有限公司研究院 | Optical signal transmission method, device and equipment |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7650175B2 (en) * | 2005-03-10 | 2010-01-19 | Shenzhen Mindray Bio-Medical Electronics Co., Ltd. | Method and device for detecting fault in a blood oxygen sensor |
| CN102389313A (en) * | 2011-08-17 | 2012-03-28 | 天津大学 | Device and method for measuring square wave modulated photoelectric volume pulse wave |
| CN102846323A (en) * | 2011-07-01 | 2013-01-02 | 中国计量学院 | LED-based noninvasive blood oxygen saturation tester |
-
2015
- 2015-04-21 CN CN201510190534.XA patent/CN104887244B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7650175B2 (en) * | 2005-03-10 | 2010-01-19 | Shenzhen Mindray Bio-Medical Electronics Co., Ltd. | Method and device for detecting fault in a blood oxygen sensor |
| CN102846323A (en) * | 2011-07-01 | 2013-01-02 | 中国计量学院 | LED-based noninvasive blood oxygen saturation tester |
| CN102389313A (en) * | 2011-08-17 | 2012-03-28 | 天津大学 | Device and method for measuring square wave modulated photoelectric volume pulse wave |
Non-Patent Citations (3)
| Title |
|---|
| 动态光谱数据分析与脉搏血氧测量***;孙兆敏;《中国优秀硕士学位论文全文数据库医药卫生科技辑》;20110715;正文第28-30页 * |
| 基于多波长LED的动态光谱测量***;李娜;《中国优秀硕士学位论文全文数据库工程科技Ⅱ辑》;20111215;全文 * |
| 多通道近红外光谱血氧监测***的研制;杜煊;《中国优秀博硕士学位论文全文数据库（硕士）工程科技Ⅱ辑》;20060515;正文第15-18页 * |
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