CN111050634B

CN111050634B - Biological feature detection method, biological feature detection device and electronic device

Info

Publication number: CN111050634B
Application number: CN201980004153.4A
Authority: CN
Inventors: 黄思衡; 王文祺
Original assignee: Shenzhen Goodix Technology Co Ltd
Current assignee: Shenzhen Goodix Technology Co Ltd
Priority date: 2019-11-21
Filing date: 2019-11-21
Publication date: 2022-08-02
Anticipated expiration: 2039-11-21
Also published as: WO2021097755A1; CN111050634A

Abstract

The application discloses a biological feature detection device (103), a biological feature detection method and an electronic device. The biometric detection device is used for controlling a light source (108) and a photoelectric converter (110) to sense the biometric characteristic of an object (101) to be detected, and comprises: a controller (106) comprising: a light source control module (1062) for controlling the light source to perform a light emitting operation during an N-step operation; the photoelectric converter control module (1064) is used for controlling the photoelectric converter to perform sampling operation for N +1 times every time the light emitting operation is performed, so as to collect an electric signal formed by a light signal (EL) emitted by the light source after passing through the object to be detected and being subjected to photoelectric conversion; and the signal processing module (1066) is used for processing the electric signals acquired according to the sampling operation of the (N +1) times to obtain the biological characteristics of the object to be detected.

Description

Biological feature detection method, biological feature detection device and electronic device

Technical Field

The present application relates to biometric detection, and more particularly, to a biometric detection method, a biometric detection apparatus, and an electronic apparatus applied to photoplethysmography (PPG).

Background

The PPG system has good application prospect in noninvasive detection of human blood pressure, blood flow, blood oxygen, cerebral oxygen, muscle oxygen, blood sugar, microcirculation peripheral blood vessel pulse rate, respiratory capacity and the like. And the PPG front-end processing module is an important component of these wearable noninvasive detection instruments. Since the skin to be measured is typically a finger or a wrist, the PPG front-end processing module may receive a large amount of ambient light noise, which mainly comes from sunlight or indoor fluorescent lamps, causing an increase in measurement error.

In view of the above, there is a need to improve the accuracy of biometric detection.

Disclosure of Invention

It is an object of the present application to disclose a biometric detection method, a biometric detection apparatus, and an electronic apparatus to solve the above-mentioned problems.

An embodiment of the present application discloses a biometric detection method for controlling a light source and a photoelectric converter to sense a biometric characteristic of an object to be detected, the biometric detection method including: controlling the light source to perform a light emitting operation during the N-order operation; controlling the photoelectric converter to perform sampling operation for N +1 times every time the light emitting operation is performed, so as to collect an electric signal formed after an optical signal emitted by the light source passes through the object to be detected and is subjected to photoelectric conversion; processing the electric signals acquired according to the sampling operation of the N +1 times to obtain the biological characteristics of the object to be detected; when N is an even number, controlling the light source and the photoelectric converter to enable the sampling time period of the (N/2+1) th sampling operation to at least partially overlap the light-emitting time period of the light-emitting operation; and when N is an odd number, controlling the light source and the photoelectric converter to enable the sampling period of the (N +1)/2 or (N +1)/2+1 sampling operation to at least partially overlap the light emitting period of the light emitting operation.

Another embodiment of the present application discloses a biometric detection apparatus for controlling a light source and a photoelectric converter to sense a biometric characteristic of an object to be detected, the biometric detection apparatus including: a controller, comprising: the light source control module is used for controlling the light source to perform light emitting operation during N-order operation; the photoelectric converter control module is used for controlling the photoelectric converter to perform sampling operation for N +1 times every time the light emitting operation is performed, so as to collect an electric signal formed by a light signal emitted by the light source after passing through the object to be detected and after being subjected to photoelectric conversion; the signal processing module is used for processing the electric signals acquired according to the sampling operation of the (N +1) times to obtain the biological characteristics of the object to be detected; wherein N is greater than 1, when N is an even number, the light source control module controls the light source, and the photoelectric converter control module controls the photoelectric converter so that a sampling period of an N/2+1 th sampling operation at least partially overlaps a light emitting period of the light emitting operation; when N is an odd number, the light source control module controls the light source, and the photoelectric converter control module controls the photoelectric converter such that a sampling period of (N +1)/2 or (N +1)/2+1 sampling operation at least partially overlaps with a light emission period of the light emission operation.

Another embodiment of the present application discloses an electronic device, including: the above-described biometric characteristic detection device; the photoelectric converter; and the light source.

The biological characteristic detection method, the biological characteristic detection device and the electronic device can improve the ambient light rejection ratio under the same sampling interval time.

Drawings

Fig. 1 is a functional block diagram of an embodiment of a biometric sensing device of the present application.

Fig. 2 is a schematic diagram of the general operation of the biometric sensing device of the present application.

Fig. 3 is an embodiment of the second-order operation of the biometric sensing device of the present application.

Fig. 4 is an example of the N-order operation of the biometric device of the present application in the case where N is an even number.

Fig. 5 is a first embodiment of the N-step operation of the biometric device of the present application in the case where N is an odd number.

Fig. 6 is a second embodiment of the N-step operation of the biometric sensing device of the present application in the case where N is an odd number.

Fig. 7 is a schematic diagram of an embodiment of an electronic device including a biometric detection device of the present application.

Detailed Description

When pulse period or cardiovascularity oxygen is measured by photoplethysmography (PPG), light is irradiated to the skin to detect the volume change of blood perfusion between the dermis and the subcutaneous tissue, and when the volume of blood perfusion changes, the absorption of light changes, so that the subcutaneous blood plethysmogram can be obtained from the measured intensity of reflected light to reflect the heart rate and the cardiovascularity oxygen state.

Fig. 1 is a functional block diagram of an embodiment of a biometric sensing device of the present application. The biometric detection device 103, the light source 108 and the photoelectric converter 110 of fig. 1 constitute the PPG system 100. The biometric detection device 103 is used to control the light source 108 and the photoelectric converter 110 under a specific environment to sense a biometric characteristic of the object 101 to be detected, such as blood pressure, blood flow, blood oxygen, cerebral oxygen, muscle oxygen, blood sugar, microcirculation peripheral blood vessel pulse rate, respiration volume, and the like. In some embodiments, the photoelectric converter 110 is used to convert the sensed light into an electrical signal for the sampling operation SP and the light source 108 is used to perform the lighting operation EP. For example, the photoelectric converter 110 may be a photodiode, and the light source 108 may be an LED, but the application is not limited thereto.

The biometric detection device 103 includes a driving module 102, a receiving module 104 and a controller 106, and the controller 104 includes a light source control module 1062, a photoelectric converter control module 1064 and a signal processing module 1066. The driving module 102 is coupled between the light source control module 1062 and the light source 108; the receiving module 104 is coupled between the signal processing module 1066 and the optical-to-electrical converter 1101. When the light emission operation EP is performed, the driving module 102 controls the light source 108 to generate the incident light EL to the object 101 to be detected and causes the reflected light RL with the biological information. When the sampling operation SP is performed, the receiving module 104 controls the photoelectric converter 110 to sense the received light entering the photoelectric converter 110 to generate a current to the receiving module 104, where the received light received by the photoelectric converter 110 includes the reflected light RL with the biological information, however, if there is a gap between the PPG system 100 and the object 101 to be detected, light leakage may be caused and the received light received by the photoelectric converter 110 also includes the ambient light AL.

The light source control module 1062 of the controller 106 is used to control the light source 108 to perform the light emitting operation EP through the driving module 102; the photoelectric converter control module 1064 of the controller 106 is used to control the photoelectric converter 110 to perform the sampling operation SP through the receiving module 104. The signal processing module 1066 of the controller 106 is configured to process the electrical signal collected by the sampling operation SP to obtain a biological characteristic of the object 101 to be detected.

The driving module 102 includes a light source driver 112 for driving the light source 108, for example, if the light source 108 is an LED, the light source driver 112 is an LED driver. The receiving module 104 includes a current-to-voltage converter for converting the current output by the photoelectric converter 110 into a voltage. In some embodiments, the controller 106 is implemented by a digital circuit, and the driving module 102 may further include a digital-to-analog converter 116 coupled between the light source driver 112 and the light source control module 1062; the receiving module 104 may further include an analog-to-digital converter 118 coupled between the current-to-voltage converter 114 and the signal processing module 1066.

For the heart rate or the heart blood oxygen measurement, the object 101 to be measured is generally a finger or a wrist, and the measurement system has a large light leakage, that is, the photoelectric converter 110 receives a large ambient light AL, which may cause an increase in measurement error if the ambient light AL cannot be effectively eliminated. Generally, as shown in fig. 2, the controller 106 controls the light source 108 to perform the light emitting operation EP once, the photoelectric converter 110 performs the sampling operations SP1 and SP2 twice correspondingly, and the light emitting operation EP and the sampling operations SP1 and SP2 are performed periodically and have a period T _PF E.g. period T _PF At 40 msec (i.e., at a frequency of 25 Hz).

While the lighting operation EP is in progress, the light source 108 is lit to create a lighting period, at which time the sampling operation SP1 is performed to at least partially overlap the sampling period of the sampling operation SP1 with the lighting period of the lighting operation EP to simultaneously sample the reflected light RL and the ambient light AL, in some embodiments, the start time of the lighting operation EP may be slightly earlier than the start time of the sampling operation SP1 to ensure that the light source 108 has stabilized; and the end time of the lighting operation EP, i.e., the time to turn off the light source 108, may be the same as the end time of the sampling operation SP 1. The sampling result D1 of the sampling operation SP1 is obtained after the sampling operation SP1 is completed, and is output to the controller 106 by the adc 118.

Then, the sampling operation SP2 is performed after the light source 108 is turned off, in other words, the sampling period of the sampling operation SP2 does not overlap with the light emitting period of the light emitting operation EP, so that the ambient light AL can be simply sampled. Here at each period T _PF The ambient light AL is sampled only once, referred to as a first order operation. The sampling interval time of the sampling operation SP1 and the sampling operation SP2 is T _INT And the time lengths of the sampling periods of the sampling operations SP1 and SP2 are all the same. The sampling result D2 of the sampling operation SP2 is obtained after the sampling operation SP2 is completed, and is output to the controller 106 by the adc 118. The controller 106 subtracts the results of the sampling operations SP1 and SP2 to produce a biometric sampling result D _R . And the next period T _PF The PPG system 100 repeats the lighting operation EP, the sampling operations SP1 and SP 2. It should be noted that the controller 106 resets the photoelectric converter 110 after the sampling operations SP1 and SP2 are completed, so as to prevent the results of the sampling operations SP1 and SP2 from interfering with each other.

The ambient light AL mainly comprises sunlight (frequency is DC) or an indoor daylight lamp (frequency is 50Hz/60Hz), so the frequency f of the ambient light AL _AL Is a low frequency signal. The ambient light rejection ratio obtained in the manner of fig. 2 is:

ambient light rejection ratio 1/(2sin (pi. f) _AL *T _INT ))

The larger the ambient light rejection ratio, the better the rejection capability of the PPG system 100 against the ambient light AL. Thus, the sampling interval time is T _INT The smaller the ambient light rejection ratio, the smaller the sampling interval time, the shorter the time length of the sampling period representing the sampling operations SP1 and SP2, causing the sampling noise to be larger, creating a dilemma. In high accuracy heart rate and cod applications, the time length of the sampling period needs to be about 80 microseconds or more, corresponding to an ambient light rejection ratio of 30dB or less, but an ambient light rejection ratio of 50dB or more is required for this application. Therefore, the present application proposes the following embodiments to improve the above problem, in brief, the controller 106 controls the light source 108 to perform the light emitting operation EP once, and the photoelectric converter 110 performs the sampling operations SP1, SP2, SP3, … three times or more correspondingly, i.e. each period T _PF The ambient light AL is sampled more than twice, i.e. a second order operation or a higher order operation. The details of which will be described later.

Fig. 3 is an embodiment of the second-order operation of the biometric sensing device of the present application. Drawing (A)3 like fig. 2, the light emission operation EP and the sampling operations SP1, SP2, SP3 are performed periodically with a period T _PF The sampling intervals of the sampling operations SP1, SP2 and SP3 are all T _INT And the time lengths of the sampling periods of the sampling operations SP1, SP2, SP3 are all the same. Fig. 3 is different from fig. 2 in that the embodiment of fig. 3 is a second-order operation, the light source control module 1062 of the controller 106 controls the light source 108 to perform the light emitting operation EP every time through the driving module 102, and the photoelectric converter control module 1064 of the controller 106 controls the photoelectric converter 110 to perform the sampling operations SP1, SP2, and SP3 three times correspondingly.

Specifically, in the embodiment of fig. 3, compared to fig. 2, the sampling operation SP1 is performed once more before the light emission operation EP is performed, in other words, the sampling period of the sampling operation SP1 does not overlap with the light emission period of the light emission operation EP, and the ambient light AL can be simply sampled. The sampling result D1 of the sampling operation SP1 is obtained after the sampling operation SP1 is completed, and is output to the signal processing module 1066 of the controller 106 by the adc 118.

At the beginning of the lighting operation EP, the light source 108 is turned on to cause a lighting period, at which time the sampling operation SP2 is performed to at least partially overlap the sampling period of the sampling operation SP2 with the lighting period of the lighting operation EP to simultaneously sample the reflected light RL and the ambient light AL, in some embodiments, the starting time of the lighting operation EP is slightly earlier than the starting time of the sampling operation SP2 to ensure that the light source 108 has stabilized; and the end time of the lighting operation EP, i.e., the time to turn off the light source 108, may be the same as the end time of the sampling operation SP 2. The sampling result D2 of the sampling operation SP2 is obtained after the sampling operation SP2 is completed, and is output to the signal processing module 1066 of the controller 106 by the adc 118.

Next, the sampling operation SP3 is performed after the light source 108 is turned off, in other words, the sampling period of the sampling operation SP3 does not overlap with the light emitting period of the light emitting operation EP to simply sample the ambient light AL. The sampling result D3 of the sampling operation SP3 is obtained after the sampling operation SP3 is completed, and is output to the signal processing module 1066 of the controller 106 by the adc 118. Signal processing moduleBlock 1066 generates a biometric sample result D based on the results of the sampling operations SP1, SP2, and SP3 _R . In particular, the biometric sampling result D _R Is (2X D2-D1-D3)/2. In the next period TPF, the PPG system 100 repeats the lighting operation EP, the sampling operations SP1, SP2, SP 3. It should be noted that the photoelectric converter control module 1064 resets the photoelectric converter 110 after the sampling operations SP1, SP2, and SP3 are completed, so as to avoid the interference of the results of the sampling operations SP1, SP2, and SP 3.

The ambient light rejection ratio obtained in the manner of fig. 3 is:

ambient light inhibition ratio of 1/(2sin (pi. f) _AL *T _INT )) ²

In contrast to the approach of fig. 2, at the sampling interval time T _INT The PPG system 100, which operates in the second order, has a high ambient light rejection ratio, for example, in high accuracy heart rate and cod applications, the time duration of the sampling period is required to be about 80 microseconds, and the corresponding ambient light rejection ratio can be increased from 30dB to 60 dB.

The biometric detection device 103 of the present application is not limited to the second-order operation of fig. 3, but may also include more than two-order N-order operations, i.e. each period T is a period T _PF The ambient light AL is sampled N times. For convenience of explanation, N is separately indicated as even and odd in this application. Fig. 4 is an example of the N-order operation of the biometric device 103 of the present application in the case where N is an even number, where N is a positive integer greater than 1.

In fig. 4, the light emission operation EP and the sampling operations SP1 to SP (N +1) are periodically performed with a period T _PF The sampling intervals of the sampling operations SP 1-SP (N +1) are all T _INT And the time lengths of the sampling periods of the sampling operations SP1 to SP (N +1) are all the same. Before the light emission operation EP is performed, the (N/2) times of sampling operations SP1 to SP (N/2) are performed to obtain the sampling results D1 to D (N/2), and are output to the controller 106 by the analog-to-digital converter 118, in other words, the sampling periods of the sampling operations SP1 to SP (N/2) do not overlap with the light emission period of the light emission operation EP, and the ambient light AL can be simply sampled.

At the beginning of the lighting operation EP, the light source 108 is turned on to create a lighting period, at which time the sampling operation SP (N/2+1) is performed, such that the sampling period of the sampling operation SP (N/2+1) at least partially overlaps the lighting period of the lighting operation EP to simultaneously sample the reflected light RL and the ambient light AL, and in some embodiments, the starting time of the lighting operation EP may be slightly earlier than the starting time of the sampling operation SP2 to ensure that the light source 108 has stabilized; and the end time of the lighting operation EP, i.e., the time to turn off the light source 108, may be the same as the end time of the sampling operation SP 2. The sampling result D (N/2+1) of the sampling operation SP (N/2+1) is obtained after the sampling operation SP (N/2+1) is ended, and is outputted to the controller 106 by the ADC 118.

Then, the sampling operations SP (N/2+2) -SP (N +1) are performed after the light source 108 is turned off to obtain the sampling results D (N/2+2) -D (N +1), which are output to the controller 106 by the adc 118. In other words, the sampling period of the sampling operations SP (N/2+2) to SP (N +1) does not overlap with the light emission period of the light emission operation EP to simply sample the ambient light AL. The controller 106 generates the biometric sampling result D according to the results of the sampling operations SP 1-SP (N +1) _R . In particular, the biometric sampling result D _R Is composed of

It should be noted that the controller 106 resets the photoelectric converter 110 after the sampling operations SP 1-SP (N +1) are completed, so as to avoid the interference of the results of the sampling operations SP 1-SP (N + 1). The ambient light rejection ratio obtained in the manner of fig. 4 is:

ambient light inhibition ratio of 1/(2sin (pi. f) _AL *T _INT )) ^N

Fig. 5 is a first embodiment of the biometric authentication device 103 of the present application, in which N is an odd number, N is a positive integer greater than 1. The difference between the case where N is an odd number and the case where N is an even number is that ((N +1)/2-1) sampling operations SP1 to SP ((N +1)/2-1) are performed before the light emission operation EP is performed, and that ((N +1)/2) sampling operations SP ((N +1)/2) to SP (N +1) are performed after the light emission operation EP is performed.

Fig. 6 is a second embodiment of the biometric authentication device 103 of the present application, in which N is an odd number, N being a positive integer greater than 1. The difference from the embodiment of fig. 5 is that ((N +1)/2) sampling operations SP1 to SP ((N +1)/2) are performed before the light emission operation EP of fig. 6 is performed, and that sampling operations SP ((N +1)/2+1) are performed when the light emission operation EP starts to be performed, and ((N +1)/2-1) sampling operations SP ((N +1)/2+2) to SP (N +1) are performed after the light emission operation EP is performed.

In the PPG system 100, the power consumption when the light source 108 is lit is much larger than when the photoelectric converter 110 is activated, in other words, the time length of the light emitting period of the light emitting operation EP substantially determines the overall power consumption of the PPG system 100. The high-order PPG system of the present application utilizes an increase in the number of sampling periods of the sampling operation SP to improve the ambient light rejection ratio, and does not have a significant impact on the overall power consumption of the PPG system 100 because the number and time length of the light emission periods of the light emission operation EP are not increased.

The biometric apparatus 103 of the present application can be implemented by a chip, which can be a semiconductor chip implemented by different processes, and the photoelectric converter 110 and the light source 108 are both disposed outside the chip of the biometric apparatus. However, the present application is not limited thereto, and in some embodiments, the photoelectric converter 110 and/or the light source 108 may also be disposed in a chip where the biometric apparatus is located.

Fig. 7 is a schematic diagram of an embodiment of an electronic device 70 including the biometric sensing device of the present application. Referring to fig. 7, the electronic device 70 comprises a PPG system 100, the PPG system 100 comprising a biometric detection device 103, a light source 108 and an opto-electric converter 110. The electronic device 70 may be a wearable electronic device, such as a watch, necklace, or any other smart wearable device. The electronic device 70 may also be a handheld electronic device, such as a smart phone, a personal digital assistant, a handheld computer system, a tablet computer, or the like.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A biometric detection method, comprising:

controlling a light source to emit light to the object to be detected during the N-order operation;

controlling a photoelectric converter to perform sampling operation for N +1 times every time the light emitting operation is performed, so as to collect an electric signal formed by a light signal emitted by the light source after passing through the object to be detected and being subjected to photoelectric conversion, wherein N is greater than 1; and

processing the electric signals acquired according to the N +1 times of sampling operation to obtain the biological characteristics of the object to be detected;

when N is an even number, controlling the light source and the photoelectric converter to enable the sampling time period of the (N/2+1) th sampling operation to at least partially overlap with the light-emitting time period of the light-emitting operation; when N is an odd number, controlling the light source and the photoelectric converter to make the sampling period of the (N +1)/2 or (N +1)/2+1 sampling operation at least partially overlap with the light emitting period of the light emitting operation;

wherein, the processing of the electric signal acquired according to the N +1 times of sampling operation to obtain the biological characteristics of the object to be detected comprises: converting the electrical signal from a current form to a voltage form.

2. The biometric detection method according to claim 1, wherein a sampling period of only one sampling operation of the N +1 sampling operations at least partially overlaps with a light emission period of the light emission operation.

3. The biometric detection method according to claim 1, wherein a start time of the lighting operation is earlier than a start time of the sampling operation at which a sampling period at least partially overlaps the lighting operation.

4. The biometric detection method according to claim 1, wherein controlling the light source to perform the lighting operation includes:

and controlling the light source to periodically perform the light emitting operation.

5. The biometric detection method according to claim 1, wherein controlling the photoelectric converter to perform the sampling operation N +1 times comprises:

and resetting the photoelectric converters respectively after the N +1 sampling operations are finished.

6. The biometric detection method according to claim 1, wherein the sampling periods of the N +1 sampling operations are all the same in time length.

7. A biometric detection device, characterized by comprising:

a controller, comprising:

the light source control module is used for controlling the light source to perform light emitting operation during the N-order operation;

the photoelectric converter control module is used for controlling the photoelectric converter to perform sampling operation for N +1 times every time the light emitting operation is performed, so as to collect an electric signal formed by a light signal emitted by the light source after passing through an object to be detected and being subjected to photoelectric conversion, wherein N is greater than 1; and

the signal processing module is used for processing the electric signals acquired according to the sampling operation of the (N +1) times to obtain the biological characteristics of the object to be detected; and

a receiving module coupled between the signal processing module and the photoelectric converter, the receiving module including a current-to-voltage converter for converting the electrical signal from a current form to a voltage form;

when N is an even number, the light source control module controls the light source, and the photoelectric converter control module controls the photoelectric converter to enable the sampling time period of the (N/2+1) th sampling operation to at least partially overlap the light-emitting time period of the light-emitting operation; when N is an odd number, the light source control module controls the light source, and the photoelectric converter control module controls the photoelectric converter such that a sampling period of (N +1)/2 or (N +1)/2+1 sampling operation at least partially overlaps with a light emission period of the light emission operation.

8. The biometric detection device according to claim 7, wherein the light source control module controls the light source and the photoelectric converter control module controls the photoelectric converter in the N +1 sampling operations such that a sampling period of only one sampling operation at least partially overlaps a light emission period of the light emission operation.

9. The biometric detection device according to claim 7, wherein the light source control module controls the light source, and the photoelectric converter control module controls the photoelectric converter such that a start time of the lighting operation at least partially overlaps a start time of the sampling operation of the lighting operation earlier than a sampling period.

10. The biometric detection device according to claim 7, wherein the light source control module controls the light source to periodically perform the light emitting operation.

11. The biometric sensing device according to claim 7, wherein the photoelectric converter control module resets the photoelectric converters respectively after the N +1 sampling operations are completed.

12. The biometric detection device according to claim 7, wherein the photoelectric converter control module controls the photoelectric converters so that the time lengths of the sampling periods of the N +1 sampling operations are all the same.

13. The biometric sensing device as recited in claim 7, further comprising a driving module coupled between the light source control module and the light source.

14. The biometric detection device recited in claim 13 wherein the drive module includes a light source driver for driving the light source.

15. The biometric detection device recited in claim 14 wherein the driver module further comprises a digital-to-analog converter coupled between the light source driver and the light source control module.

16. The biometric detection device recited in claim 7 wherein the receiving module further comprises an analog-to-digital converter coupled between the current-to-voltage converter and the opto-electric converter control module.

17. An electronic device, comprising:

the biometric detection device as recited in any one of claims 7-16;

the photoelectric converter; and

the light source.

18. The electronic device of claim 17, wherein the photoelectric converter is a photodiode and the light source is an LED.