CN111050634B - Biometric detection method, biometric detection device and electronic device - Google Patents

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

Biometric detection method, biometric detection device and electronic device

technical field

The present application relates to biometric detection, and in particular, to a biometric detection method, a biometric detection device and an electronic device applied to photoplethysmogram (PPG).

Background technique

The PPG system has good application prospects in the non-invasive detection of human blood pressure, blood flow, blood oxygen, brain oxygen, muscle oxygen, blood sugar, microcirculation peripheral blood vessel pulse rate, respiratory rate and respiratory capacity. The PPG front-end processing module is an important part of these wearable non-invasive testing instruments. Because the skin to be tested is generally fingers or wrists, the PPG front-end processing module may receive large ambient light noise, which mainly comes from sunlight or indoor fluorescent lamps, resulting in increased measurement errors.

In view of this, it is necessary to improve the accuracy of biometric detection.

SUMMARY OF THE INVENTION

One of the objectives of the present application is to disclose a biometric detection method, a biometric detection device and an electronic device to solve the above problems.

An embodiment of the present application discloses a biological feature detection method, which is used to control a light source and a photoelectric converter to sense biological features of an object to be detected. The biological feature detection method includes: during an N-stage operation, controlling the The light source performs a light-emitting operation; every time the light-emitting operation is performed, the photoelectric converter is controlled to perform N+1 sampling operations to collect the light signal emitted by the light source after passing through the object to be detected and being photoelectrically converted. an electrical signal; and process the electrical signal collected according to the N+1 sampling operations to obtain the biological feature of the object to be detected; wherein N is greater than 1, and when N is an even number, the light source and the photoelectric converter are controlled, so that the sampling period of the N/2+1th sampling operation at least partially overlaps the light-emitting period of the light-emitting operation; when N is an odd number, the light source and the photoelectric converter are controlled so that the (N+1th) )/2 times or (N+1)/2+1 times the sampling period of the sampling operation at least partially overlaps the light-emitting period of the light-emitting operation.

Another embodiment of the present application discloses a biological feature detection device, which is used to control a light source and a photoelectric converter to sense biological features of an object to be detected. The biological feature detection device includes: a controller, including: a light source control module , which is used to control the light source to perform light-emitting operation during the N-order operation; the photoelectric converter control module is used to control the photoelectric converter to perform N+1 sampling operations every time the light-emitting operation is performed to collect all the an electrical signal formed after the optical signal emitted by the light source passes through the object to be detected and is photoelectrically converted; and a signal processing module, configured to process the electrical signal collected by the N+1 sampling operations to obtain the object to be detected The biometric feature; 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 the N/2+1th sampling The sampling period of the operation at least partially overlaps the 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 so that the first The sampling period of the (N+1)/2th or (N+1)/2+1th sampling operation at least partially overlaps the light-emitting period of the light-emitting operation.

Another embodiment of the present application discloses an electronic device, comprising: the above-mentioned biological feature detection device; the photoelectric converter; and the light source.

The biometric detection method, biometric detection device and electronic device of the present application can improve the ambient light suppression ratio under the same sampling interval.

Description of drawings

FIG. 1 is a schematic functional block diagram of an embodiment of a biometric detection apparatus of the present application.

FIG. 2 is a schematic diagram of the general operation of the biometric detection device of the present application.

FIG. 3 is an embodiment of the second-order operation of the biometric detection device of the present application.

FIG. 4 is an embodiment of N-order operations of the biometric detection apparatus of the present application when N is an even number.

FIG. 5 is a first embodiment of an N-order operation of the biometric detection apparatus of the present application when N is an odd number.

FIG. 6 is a second embodiment of the N-order operation of the biometric detection device of the present application when N is an odd number.

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

Detailed ways

When photoplethysmogram (PPG) is used to measure pulse cycle or cardiac blood oxygen, light is used to illuminate the skin to detect the volume change of blood perfusion in the dermis and subcutaneous tissue. The amount of light absorption also changes, and the subcutaneous blood plethysmogram can be obtained from the measured reflected light intensity to reflect the heart rate and cardiac blood oxygen status.

FIG. 1 is a schematic functional block diagram of an embodiment of a biometric detection apparatus 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 in a specific environment to sense the biometric characteristics of the object to be detected 101, such as blood pressure, blood flow, blood oxygen, brain oxygen, muscle oxygen, blood sugar, Microcirculation peripheral blood vessel pulse rate, respiratory rate and respiratory capacity, etc. In some embodiments, the photoelectric converter 110 is used to convert the sensed light into an electrical signal to perform 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 present application is not limited thereto.

The biometric detection device 103 includes a driving module 102 , a receiving module 104 and a controller 106 . 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 photoelectric converter 1101 . When the light-emitting operation EP is performed, the driving module 102 controls the light source 108 to generate incident light EL to the object to be detected 101 and generate reflected light RL with 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. The received light received by the photoelectric converter 110 includes biological information. However, if there is a gap between the PPG system 100 and the object to be detected 101, light leakage will be caused and the received light received by the photoelectric converter 110 will also include ambient light AL.

The light source control module 1062 of the controller 106 is used for controlling the light source 108 to perform the lighting operation EP through the driving module 102; The signal processing module 1066 of the controller 106 is configured to process the electrical signal collected according to the sampling operation SP to obtain the biological feature of the object to be detected 101 .

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-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 The converter 118 is coupled between the current-to-voltage converter 114 and the signal processing module 1066 .

For heart rate or cardiac oxygen measurement, the object 101 to be detected is generally a finger or a wrist, and the testing system will have a large light leakage, that is, the photoelectric converter 110 will receive a large ambient light AL. Elimination of ambient light AL will cause measurement errors to rise. As shown in FIG. 2 , the controller 106 controls the light source 108 to perform one lighting operation EP, the photoelectric converter 110 correspondingly performs two sampling operations SP1 and SP2, and the lighting operation EP and the sampling operations SP1 and SP2 are cycles This is done in a linear fashion, with a period T _PF , eg a period T _PF of 40 milliseconds (ie a frequency of 25 Hz).

When the light-emitting operation EP is performed, the light source 108 is turned on to form a light-emitting period, and at this time, the sampling operation SP1 is performed, so that the sampling period of the sampling operation SP1 at least partially overlaps the light-emitting period of the light-emitting operation EP, so that the reflected light RL and the ambient light are not affected. AL performs sampling at the same time. In some embodiments, the start time of the lighting operation EP is slightly earlier than the start time of the sampling operation SP1 to ensure that the light source 108 is stable; and the end time of the lighting operation EP is the time to turn off the light source 108 , which can be the same as the end time of the sampling operation SP1. The sampling result D1 of the sampling operation SP1 is obtained after the sampling operation SP1 ends, and is output to the controller 106 by the analog-to-digital converter 118 .

Next, 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 lighting period of the lighting operation EP, so that the ambient light AL can be simply sampled. Here, in each cycle T _PF , the ambient light AL is sampled only once, which is called a first-order operation. The sampling interval time of the sampling operations SP1 and SP2 is T _INT , and the time lengths of the sampling periods of the sampling operations SP1 and SP2 are the same. The sampling result D2 of the sampling operation SP2 is obtained after the sampling operation SP2 ends, and is output to the controller 106 by the analog-to-digital converter 118 . The controller 106 subtracts the results of the sampling operations SP1 and SP2 to generate the biometric sampling result _DR . In the next period T _PF , the PPG system 100 will repeat the light-emitting operation EP and the sampling operations SP1 and SP2 . 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 avoid mutual interference between the results of the sampling operations SP1 and SP2.

The ambient light AL mainly includes sunlight (the frequency is DC) or indoor fluorescent lamps (the frequency is 50Hz/60Hz), so the frequency f _AL of the ambient light AL is a low-frequency signal. The ambient light suppression ratio obtained by the method of Figure 2 is:

Ambient light rejection ratio = 1/(2sin(π*f _AL *T _INT ))

The larger the ambient light suppression ratio, the better the ability of the PPG system 100 to suppress ambient light AL. Therefore, the smaller the sampling interval time is T _INT , the greater the ambient light suppression ratio, but the smaller the sampling interval time, the shorter the time length of the sampling period of the sampling operations SP1 and SP2, which will result in greater sampling noise and form a dilemma. situation. In the application of high-precision heart rate and cardiovascular oxygen measurement, the time length of the sampling period needs to be more than 80 microseconds, and the corresponding ambient light suppression ratio is less than 30dB, but the ambient light suppression ratio required in this application is 50dB above. Therefore, the present application proposes the following embodiments to improve the above problems. In short, the controller 106 controls the light source 108 to perform one light-emitting operation EP, and the photoelectric converter 110 correspondingly performs more than three sampling operations SP1, SP2, SP3, . . . , that is, in each period T _PF , the ambient light AL is sampled more than twice, that is, a second-order operation or a higher-order operation. Details thereof will be described later.

FIG. 3 is an embodiment of the second-order operation of the biometric detection device of the present application. 3 and 2 are the same, the light-emitting 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, SP3 are all T _INT , and the sampling operations The time lengths of the sampling periods of SP1, SP2, and SP3 are all the same. The difference between FIG. 3 and FIG. 2 is 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 through the driving module 102 to perform a lighting operation EP. The photoelectric converter control module of the controller 106 1064 controls the photoelectric converter 110 to perform three sampling operations SP1, SP2, SP3 correspondingly.

Specifically, in the embodiment of FIG. 3 compared with FIG. 2 , one more sampling operation SP1 is performed before the light-emitting operation EP is performed. In other words, the sampling period of the sampling operation SP1 does not overlap with the light-emitting period of the light-emitting operation EP. The ambient light AL may simply be sampled. The sampling result D1 of the sampling operation SP1 is obtained after the sampling operation SP1 is completed, and is output by the analog-to-digital converter 118 to the signal processing module 1066 of the controller 106 .

When the light-emitting operation EP starts, the light source 108 is turned on to create a light-emitting period, and at this time, the sampling operation SP2 is performed so that the sampling period of the sampling operation SP2 at least partially overlaps the light-emitting period of the light-emitting operation EP, so as to prevent the reflected light RL and the environment The light AL is sampled at the same time. In some embodiments, the start time of the lighting operation EP is slightly earlier than the start time of the sampling operation SP2 to ensure that the light source 108 is stable; and the end time of the lighting operation EP is to turn off the light source 108. The time may be the same as the end time of the sampling operation SP2. The sampling result D2 of the sampling operation SP2 is obtained after the sampling operation SP2 ends, and is output to the signal processing module 1066 of the controller 106 by the analog-to-digital converter 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 lighting period of the lighting operation EP, so as to simply sample the ambient light AL. The sampling result D3 of the sampling operation SP3 is obtained after the sampling operation SP3 ends, and is output to the signal processing module 1066 of the controller 106 by the analog-to-digital converter 118 . The signal processing module 1066 generates a biometric sampling result _DR according to the results of the sampling operations SP1, SP2, SP3. Specifically, the biometric sampling result _DR is (2*D2-D1-D3)/2. In the next period of TPF, the PPG system 100 will repeat the light-emitting operation EP and the sampling operations SP1 , SP2 , and SP3 . 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 mutual interference between the results of the sampling operations SP1 , SP2 and SP3 .

The ambient light suppression ratio obtained by the method in Figure 3 is:

Ambient light rejection ratio = 1/(2sin(π*f _AL *T _INT )) ²

Compared with the method of FIG. 2 , the PPG system 100 of the second-order operation has a higher ambient light rejection ratio when the sampling interval T _INT is unchanged, such as in the application of high-precision heart rate and cardiovascular oxygen measurement. , the time length of the sampling period is about 80 microseconds, and the corresponding ambient light suppression ratio can be increased from 30dB to 60dB.

The biometric detection device 103 of the present application is not limited to the second-order operation shown in FIG. 3 , and may also include N-order operations of two or more orders, that is, sampling the ambient light AL N times in each period T _PF . For the convenience of description, in this application, N is an even number and an odd number to be represented separately. FIG. 4 is an embodiment of the N-order operation of the biometric detection apparatus 103 of the present application when N is an even number, and N is a positive integer greater than 1. As shown in FIG.

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

When the light-emitting operation EP starts to be performed, the light source 108 is turned on to cause a light-emitting period, and at this time, the sampling operation SP(N/2+1) is performed so that the sampling period of the sampling operation SP(N/2+1) at least partially overlaps with The lighting period of the lighting operation EP is to sample the reflected light RL and the ambient light AL at the same time. In some embodiments, the start time of the lighting operation EP is slightly earlier than the start time of the sampling operation SP2 to ensure that the light source 108 has stabilized ; and the end time of the lighting operation EP, that is, the time when the light source 108 is turned off, may be the same as the end time of the sampling operation SP2. 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 completed, and is output to the controller 106 by the analog-to-digital converter 118 .

Next, 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 obtained by The analog to digital converter 118 outputs to the controller 106 . In other words, the sampling period of the sampling operations SP(N/2+2)˜SP(N+1) does not overlap with the light-emitting period of the light-emitting operation EP to simply sample the ambient light AL. The controller 106 generates a biometric sampling result DR according to the results of the sampling operations SP1-SP(N ₊ 1). Specifically, the biometric sampling result _DR is

It should be noted that the controller 106 resets the photoelectric converter 110 after the sampling operations SP1-SP(N+1) are finished, so as to avoid mutual interference between the results of the sampling operations SP1-SP(N+1). The ambient light suppression ratio obtained by the method in Figure 4 is:

Ambient light rejection ratio = 1/(2sin(π*f _AL *T _INT )) ^N

FIG. 5 shows the first embodiment of the N-order operation of the biometric detection apparatus 103 of the present application when N is an odd number, and N is a positive integer greater than 1. As shown in FIG. The difference from N is an even number is that when N is an odd number, before the light-emitting operation EP is performed, ((N+1)/2-1) sampling operations SP1 to SP((N+1)/2-1) are performed, When the light-emitting operation EP starts, the sampling operation SP((N+1)/2) is performed, and after the light-emitting operation EP is performed, the sampling operation SP((N+1)/2) is performed ((N+1)/2) times. 2+1)～SP(N+1).

FIG. 6 is a second embodiment of the N-order operation of the biometric detection apparatus 103 of the present application when N is an odd number, and N is a positive integer greater than 1. As shown in FIG. The difference from the embodiment in FIG. 5 is that before the light-emitting operation EP in FIG. 6 is performed, ((N+1)/2) sampling operations SP1 to SP((N+1)/2) are performed, and before the light-emitting operation EP is performed, At the beginning, the sampling operation SP((N+1)/2+1) is performed, and after the light-emitting operation EP is performed, ((N+1)/2-1) sampling operations SP((N+1)/ 2+2)～SP(N+1).

In the PPG system 100 , the power consumption when the light source 108 is turned on is much greater than the power consumption when the photoelectric converter 110 is activated. The high-order PPG system of the present application improves the ambient light suppression ratio by increasing the number of sampling periods of the sampling operation SP. Since the number and time length of the light-emitting periods of the light-emitting operation EP are not increased, the overall power consumption of the PPG system 100 is not affected. big.

The biometric detection device 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 where the biometric detection device is located. However, the present application is not limited to this. In some embodiments, the photoelectric converter 110 and/or the light source 108 may also be disposed in the chip where the biometric detection device is located.

FIG. 7 is a schematic diagram of an embodiment of an electronic device 70 including the biometric detection device of the present application. 7 , the electronic device 70 includes a PPG system 100, and the PPG system 100 includes a biometric detection device 103, a light source 108, and a photoelectric converter 110. The electronic device 70 can be a wearable electronic device, such as a watch, a necklace or any other smart wearable device. The electronic device 70 can also be a handheld electronic device, such as a smart phone, a personal digital assistant, a handheld computer system, or a tablet computer.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (18)

1. a biological feature detection method, is characterized in that, described biological feature detection method comprises: During the N-stage operation, the light source is controlled to emit light to the object to be detected; Each time the light-emitting operation is performed, the photoelectric converter is controlled to perform N+1 sampling operations to collect the electrical signal formed by the light signal emitted by the light source passing through the object to be detected and being photoelectrically converted, wherein N is greater than 1; as well as The biological feature of the object to be detected is obtained by processing the electrical signal collected according to the N+1 sampling operations; When N is an even number, control the light source and the photoelectric converter so that the sampling period of the N/2+1th sampling operation at least partially overlaps the light-emitting period of the light-emitting operation; when N is an odd number, control the the light source and the photoelectric converter, so that the sampling period of the (N+1)/2th or (N+1)/2+1th sampling operation at least partially overlaps the light-emitting period of the light-emitting operation; The processing of the electrical signals collected according to the N+1 sampling operations to obtain the biological features of the object to be detected includes: converting the electrical signals from a current form to a voltage form. 2 . The biometric detection method according to claim 1 , wherein among the N+1 sampling operations, the sampling period of only one sampling operation at least partially overlaps the lighting period of the lighting operation. 3 . 3. The biometric detection method of claim 1, wherein a start time of the lighting operation is earlier than a sampling period at least partially overlapping a start time of the sampling operation of the lighting operation. 4. The biometric detection method according to claim 1, wherein controlling the light source to perform the light-emitting operation comprises: The light source is controlled to periodically perform the light-emitting operation. 5. The biometric detection method according to claim 1, wherein controlling the photoelectric converter to perform N+1 sampling operations comprises: The photoelectric converters are respectively reset after the N+1 sampling operations are completed. 6 . The biometric detection method according to claim 1 , wherein the time lengths of the sampling periods of the N+1 sampling operations are all the same. 7 . 7. A biometric detection device, wherein the biometric detection device comprises: Controller, including: The light source control module is used to control the light source to perform light-emitting operation during the N-order operation; The photoelectric converter control module is used to control the photoelectric converter to perform N+1 sampling operations every time the light-emitting operation is performed, so as to collect the electrical signal formed by the light signal emitted by the light source after passing through the object to be detected and being photoelectrically converted , where N is greater than 1; and a signal processing module, configured to process the electrical signals collected by the N+1 sampling operations to obtain the biological features of the object to be detected; and a receiving module, coupled between the signal processing module and the photoelectric converter, the receiving module includes a current-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 so that the sampling period of the N/2+1th sampling operation at least partially overlaps the the 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 so that the (N+1)/2th or The sampling period of the (N+1)/2+1 th sampling operation at least partially overlaps the light-emitting period of the light-emitting operation. 8. The biometric detection device according to claim 7, wherein in the N+1 sampling operations, the light source control module controls the light source, and the photoelectric converter control module controls the photoelectric converter, so that the sampling period of only one sampling operation at least partially overlaps the light-emitting period of the light-emitting operation. 9. The biometric detection device of claim 7, wherein the light source control module controls the light source, and the photoelectric converter control module controls the photoelectric converter so that the start time of the light-emitting operation is earlier The sampling period at least partially overlaps the start time of the sampling operation of the lighting operation. 10 . The biometric detection device of claim 7 , wherein the light source control module controls the light source to periodically perform the light-emitting operation. 11 . 11 . The biometric detection 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 . 12 . The biometric detection device of claim 7 , wherein the photoelectric converter control module controls the photoelectric converter so that the time lengths of the sampling periods of the N+1 sampling operations are all the same. 13 . 13. The biometric detection device of claim 7, further comprising a driving module coupled between the light source control module and the light source. 14. The biometric detection device of claim 13, wherein the driving module comprises a light source driver for driving the light source. 15. The biometric detection device of claim 14, wherein the driving module further comprises a digital-to-analog converter, which is coupled between the light source driver and the light source control module. 16. The biometric detection device according to claim 7, wherein the receiving module further comprises an analog-to-digital converter, which is coupled between the current-voltage converter and the photoelectric converter control module. 17. An electronic device comprising: The biometric detection device according to 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.

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