WO2021098694A1

WO2021098694A1 - Ppg testing circuit and method, and wearable electronic device

Info

Publication number: WO2021098694A1
Application number: PCT/CN2020/129621
Authority: WO
Inventors: 刘恩福
Original assignee: Oppo广东移动通信有限公司
Priority date: 2019-11-18
Filing date: 2020-11-18
Publication date: 2021-05-27
Also published as: CN112806972B; CN112806972A

Abstract

A PPG testing circuit, comprising: a light-emitting component (110), used for transmitting optical signals according to a driving signal; a photosensitive component (120), comprising a first photoelectric sensor (PD1) and a second photoelectric sensor (PD2) connected in parallel to one other, wherein the first photoelectric sensor (PD1) is used for collecting ambient light and the optical signal and outputting a first optical current signal, the second photoelectric sensor (PD2) is used for collecting ambient light and the optical signals and outputting a second optical current signal, and the luminous flux of the optical signals respectively collected by the first photoelectric sensor (PD1) and the second photoelectric sensor (PD2) is different; and an analog front-end processing component (130), which is connected to the light-emitting component (110), the first photoelectric sensor (PD1) and the second photoelectric sensor (PD2) respectively, and is used for sending the driving signal to the light-emitting component (110) and performing the differential processing analysis according to the received first optical current signal and second optical current signal to acquire a PPG testing result.

Description

PPG test circuit and method, wearable electronic equipment

Cross-references to related applications

This application claims the priority of a Chinese patent application filed with the Chinese Patent Office, the application number is 2019111287296, and the invention title is "PPG test circuit and method, wearable electronic equipment" on November 18, 2019, the entire content of which is incorporated by reference In this application.

Technical field

This application relates to electronic equipment, in particular to a PPG test circuit and method, and wearable electronic equipment.

Background technique

The statements here only provide background information related to this application, and do not necessarily constitute existing exemplary technologies.

Wearable electronic devices can measure vital signs such as heart rate and blood oxygen saturation by setting up PPG (Photoplethysmo Graphy) sensor modules and based on PPG technology. PPG is a method that uses photoplethysmography technology to detect vital signs signals such as human exercise heart rate and blood oxygen saturation. When performing PPG measurement, the PPG sensor module not only receives light from the light-emitting components, but also receives ambient light (such as sunlight, fluorescent lamps, incandescent lamps, etc.), which will affect the PPG measurement.

Generally, in order to eliminate ambient light, one is to plate a film to remove infrared light on the PPG sensor module, but its cost is high and the test range is small; instead, a measurement circuit with a larger input range is used to collect ambient light in time, and then Subtracting ambient light in the digital domain, its power consumption is high.

Summary of the invention

According to various embodiments of the present application, a PPG test circuit and method, and a wearable electronic device are provided.

A PPG test circuit, including:

The light-emitting component is used to emit a light signal according to the driving signal;

The photosensitive component includes a first photoelectric sensor and a second photoelectric sensor connected in parallel, wherein the first photoelectric sensor is used to collect ambient light and the light signal and output a first photocurrent signal, and the second photoelectric sensor is used to collect The ambient light and the light signal and output the second photocurrent signal, wherein the light fluxes of the light signals respectively collected by the first photoelectric sensor and the second photoelectric sensor are different;

The analog front-end processing component is connected to the light-emitting component, the first photoelectric sensor and the second photoelectric sensor respectively, and is used to send the driving signal to the light-emitting component, and according to the received first photocurrent signal and the second photoelectric sensor. The photocurrent signal is differentially processed and analyzed to obtain the PPG test result.

A PPG test method, including:

Drive the light-emitting component to emit light signals;

Control the first photoelectric sensor to collect the ambient light and the light signal and output a first photocurrent signal, and control the second photoelectric sensor to collect the ambient light and the light signal and output the second photocurrent signal, wherein the The first photoelectric sensor is connected in parallel with the second photoelectric sensor, wherein the light fluxes of the optical signals respectively collected by the first photoelectric sensor and the second photoelectric sensor are different;

Perform differential processing and analysis according to the received first photocurrent signal and the second photocurrent signal to obtain the PPG test result.

A wearable electronic device, including:

The housing, including the exposed photosensitive detection surface;

As in the above-mentioned PPG test circuit, the light-emitting component and the photosensitive component are both arranged on the photosensitive detection surface, and the analog front-end processing component is arranged in the housing.

In the above-mentioned PPG test circuit and method, and wearable electronic equipment, the light fluxes of the optical signals collected by the first photoelectric sensor and the second photoelectric sensor are different, and by connecting the first photoelectric sensor and the second photoelectric sensor in parallel, the analog front-end processing The component can perform differential processing on the first photocurrent signal output by the first photoelectric sensor and the second photocurrent signal output by the second photoelectric sensor to cancel the photocurrent signal generated by the ambient light. Because the ambient light is suppressed at the input of the analog front-end processing component, the PPG test circuit does not need to control to turn off or turn on the light-emitting component to collect the ambient light in time, and then eliminate the ambient light in the digital domain, which can use a smaller dynamic range , Is conducive to reducing power consumption. At the same time, it can also avoid the use of coating on the surface of the photosensitive component to eliminate the influence of ambient light, which saves costs, expands the test range, and improves the test accuracy and accuracy.

The details of one or more embodiments of the present application are set forth in the following drawings and description. Other features, purposes and advantages of this application will become apparent from the description, drawings and claims.

Description of the drawings

In order to more clearly describe the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only These are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

Figure 1 is a structural block diagram of a PPG test circuit in an embodiment;

Fig. 2 is a structural block diagram of a PPG test circuit in an embodiment;

FIG. 3 is a diagram of the light trend of the PPG test circuit in an embodiment;

FIG. 4 is a diagram of the light trend of the PPG test circuit in an embodiment;

Figure 5 is a structural block diagram of a PPG test circuit in an embodiment;

FIG. 6 is a diagram of the light trend of the PPG test circuit in an embodiment;

FIG. 7 is a flowchart of a PPG test method in an embodiment;

Fig. 8 is a flowchart of a PPG test method in an embodiment.

Detailed ways

In order to make the purpose, technical solutions, and advantages of this application clearer, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the application, and not used to limit the application.

It can be understood that the terms "first", "second", etc. used in this application can be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element. For example, without departing from the scope of the present application, the first photosensor may be referred to as the second photosensor, and similarly, the second photosensor may be referred to as the first photosensor. Both the first photo sensor and the second photo sensor are photo sensors, but they are not the same photo sensor. It should be noted that the "plurality" in this application includes two or more.

The embodiment of the present application provides a PPG test circuit, and the PPG test circuit can be used in a wearable electronic device. Among them, wearable electronic devices may include wearable electronic devices such as bracelets, electronic watches, eye masks, pedometers, and earphones.

PPG (Photo Plethysmo Graphy, photoplethysmography) is a method that uses photoplethysmography technology to detect vital signs such as human exercise heart rate and blood oxygen saturation. From the perspective of PPG sensor layout, PPG detection technology can be divided into two main types: one is transmission detection technology. For example, it can trace the change of blood vessel volume during the cardiac cycle according to the difference of transmitted light intensity, and obtain the heart rate and blood Oxygen saturation, etc.; one is a reflection detection technology, for example, it can trace the changes in blood vessel volume during the cardiac cycle according to the intensity of reflected light, and obtain vital signs such as heart rate and blood oxygen saturation. Combining the PPG test circuit provided in this application to a wearable electronic device, users can conveniently detect heart rate and blood oxygen saturation anytime and anywhere, for example, users can detect heart rate and blood oxygen saturation only by touching their fingertips And so on, which not only enriches the functions of wearable electronic devices, but also greatly meets the health needs of users.

As shown in FIG. 1, in one of the embodiments, the PPG test circuit includes a light-emitting component 110, a photosensitive component 120 and an analog front-end processing component 130. Among them, the analog front-end processing component 130 is connected to the light-emitting component 110 and the photosensitive component 120 respectively.

In one of the embodiments, the light-emitting component 110 may emit light signals according to the driving signal sent by the analog front-end processing component 130. Specifically, the light-emitting assembly 110 may include one or more light-emitting units. Each light emitting unit may include one or more light emitting diodes. Specifically, the light emitting diode may be a red light emitting diode (RED LED) or an infrared light emitting diode (IR LED). For example, the light emitting unit may include a red light emitting diode and an infrared light emitting diode at the same time, and the light emitting unit may separately include a red light emitting diode or an infrared light emitting diode.

In one of the embodiments, the photosensitive assembly 120 includes a first photosensor PD1 and a second photosensor PD2 connected in parallel. The first photosensor PD1 and the second photosensor PD2 work in a zero bias state, that is, the first photosensor PD1 and the second photosensor PD2 can both be photodiodes in photovoltaic mode, that is, the first photosensor PD1 is called It is the first photodiode, and the second photo sensor PD2 is called the second photodiode. Specifically, the first photodiode and the second photodiode are connected in reverse parallel, that is, the anode of the first photodiode is connected to the cathode of the second photodiode, and the cathode of the first photodiode is connected to the anode of the second photodiode. Among them, the first photoelectric sensor PD1 can collect ambient light and light signals and output the first photocurrent signal to the analog front-end processing component 130, and the second photoelectric sensor PD2 can collect ambient light and light signals and output the second photocurrent signal to the analog front-end processing component 130 130. The first photosensor PD1 and the second photosensor PD2 respectively collect different luminous fluxes of the optical signals, so that the corresponding output photocurrent signals of the first photosensor PD1 and the second photosensor PD2 are also different.

Further, the difference between the first photocurrent signal and the second photocurrent signal can be understood as the photocurrent signal of the optical signal.

The shot noise caused by dark current of the first photoelectric sensor PD1 and the second photoelectric sensor PD2 in the photovoltaic mode is small, and there is no 1/f noise when the frequency is lower than 1kHz. The first photosensor PD1 and the second photosensor PD2 work in a zero bias state, and their output photocurrent is proportional to the incident power, but when the load resistance is large, the optical power changes with the first photosensor PD1 and the second photosensor PD2 The output current and voltage will appear nonlinear.

The first photosensor PD1 and the second photosensor PD2 are in reverse parallel connection. For example, the same input terminal of the analog front-end processing component 130 can be connected to the anode of the first photosensor PD1 and the cathode of the second photosensor PD2, respectively. The analog front-end processing component 130 can perform differential processing on the first photocurrent signal output by the first photoelectric sensor PD1 and the second photocurrent signal output by the second photoelectric sensor PD2 to cancel the photocurrent signal generated by the ambient light, and according to the difference The processed signal obtains the PPG test result. Among them, the PPG test results may include vital signs information such as pulse heart rate, blood oxygen saturation, blood sugar, blood flow and so on.

For example, when the red light emitting diode or infrared light emitting diode is used alone, the PPG test circuit can detect the reflected light intensity after absorption by human blood and tissues, and calculate the user's heart rate value; when the red light emitting diode and the infrared light emitting diode are at the same time When in use, the PPG test circuit can detect the reflected light intensity after absorption by human blood and tissues, etc., and can calculate the user's blood oxygen level, blood sugar level, etc., which further enriches the functions and performance of the PPG test circuit.

In the PPG test circuit in the embodiment of the present application, since the first photosensor PD1 and the second photosensor PD2 are connected in parallel, and the first photosensor PD1 and the second photosensor PD2 have different luminous fluxes for collecting light signals, the first photosensor is The corresponding output photocurrent signals of PD1 and PD2 are also different. The analog front-end processing component 130 can perform differential processing on the first photocurrent signal output by the first photoelectric sensor PD1 and the second photocurrent signal output by the second photoelectric sensor PD2 to cancel the photocurrent signal generated by the ambient light. Since the ambient light is suppressed at the input of the analog front-end processing component 130, the PPG test circuit does not need to control to turn off or turn on the light-emitting component 110 to collect the ambient light in time sharing, and then eliminate the ambient light in the digital domain, which can use smaller dynamics The range is conducive to reducing power consumption. At the same time, it can also avoid the use of coating on the surface of the photosensitive component 120 to eliminate the influence of ambient light, which saves costs, expands the test range, and improves the test precision and accuracy.

In one of the embodiments, as shown in FIG. 2, the analog front-end processing component 130 includes a transconductance amplifier module 131 and a driving processing module 132. The transconductance amplifier module 131 includes a positive input terminal, a negative input terminal, and an output terminal. The positive input terminal of the transconductance amplifier module 131 is used to receive the first photocurrent signal in the positive direction, and the negative input terminal of the transconductance amplifier module 131 is used to receive the second photocurrent signal in the negative direction. The output terminal of the transconductance amplifier module 131 is used to output a differential voltage obtained by performing differential processing on the first photocurrent signal and the second photocurrent signal.

Specifically, the transconductance amplifier module 131 includes a transconductance amplifier U, a first transconductance resistance R1, and a second transconductance resistance R2. Among them, the negative input end of the transconductance amplifier U is used as the negative input end of the transconductance amplifier U module 131 to connect to the cathode of the first photosensor PD1 and the anode of the second photosensor PD2, and the positive input of the transconductance amplifier U The terminal serves as the positive input terminal of the transconductance amplifier U module 131 and is respectively connected to the anode of the first photosensor PD1 and the cathode of the second photosensor PD2. The first transconductance resistance R1 is respectively connected to the negative input end and the output end of the transconductance amplifier U, and the second transconductance resistance R2 is respectively connected to the positive input end and the output end of the transconductance amplifier U. The first photocurrent signal generated by the first photosensor _{PD1 is} represented by I PD1, and the second photocurrent signal generated by the second photosensor _{PD2 is} represented _{by I PD2, and the current flow directions of I PD1} and I _PD2 are shown in FIG. 2. The transconductance amplifier U can perform differential processing according to the received first photocurrent signal I _PD1 , the second photocurrent signal I _PD2 , the first transconductance resistance R1 and the second transconductance resistance R2 to output a differential voltage U ₀ . Among them, U _o =(I _PD1 -I _PD2 )(R ₁ +R ₂ ).

After driving the processing module 132 may receive a differential voltage U ₀ U transconductance amplifier output module 131, and filters, analog-digital conversion processing on the differential voltage U _0, PPG analysis and calculation to obtain the corresponding test results.

In one of the embodiments, the first photosensor PD1 and the second photosensor PD2 have different distances from the light-emitting component. As shown in FIGS. 3 and 4, the light-emitting assembly 110 includes a first light-emitting unit LED1, wherein the first light-emitting unit LED1, the first photosensor PD1, and the second photosensor PD2 are arranged in a one-dimensional linear array, and the first light-emitting unit The first distance between the LED1 and the second photosensor PD2 is greater than the second distance between the first photosensor PD1 and the second photosensor PD2. Wherein, the difference between the first distance and the second distance is between 2 mm and 15 mm.

Taking the first light emitting unit LED1 as a red LED as an example for description. As shown in Figure 3 and Figure 4, 01 is the housing of the wearable electronic device, 02 is the user’s wrist and other biological skin tissues, 03 is the ambient light (sunlight, incandescent lamp, etc.), and 04 is the human wrist. Wait for the ambient light of the biological tissue 02. 05 represents the light emitted by the first light-emitting unit LED1 collected by the first photosensor PD1, and 06 represents the light collected by the second photosensor PD2.

The first light emitting unit LED1, the first photosensor PD1, and the second photosensor PD2 are arranged in a one-dimensional linear array, and the red LED is close to the first photosensor PD1, and the red LED is farther from the second photosensor PD2. The ambient light 03 is usually parallel light such as sunlight, and the distance between the first photoelectric sensor PD1 and the second photoelectric sensor PD2 is relatively close, so the luminous flux of the ambient light 03 received by the first photoelectric sensor PD1 and the second photoelectric sensor PD2 The difference is within the preset range, and the skin tissue of the user's human body has strong light absorption, so the amount of light emitted by the red LED is collected by the first photoelectric sensor PD1 is much greater than the amount collected by the second photoelectric sensor PD2 , The difference between the first photocurrent signal generated by the first photosensor PD1 and the second photocurrent signal generated by the second photosensor PD2 is equal to or close to the same as the photocurrent signal generated by the optical signal received by the second photosensor PD2. Since the first photosensor PD1 and the second photosensor PD2 are in reverse parallel connection, the photocurrent generated by the ambient light is suppressed.

Wherein, the difference between the luminous flux of the ambient light 03 received by the first photosensor PD1 and the second photosensor PD2 is within a preset range, that is, the luminous flux of the ambient light 03 received by the first photosensor PD1 and the second photosensor The difference of the luminous flux of the ambient light 03 received by the PD2 is within a preset range. Wherein, the preset range can be understood as a range that includes zero and is close to zero. In this application, the preset range is not further limited. For example, when the difference is within the preset range, the first photocurrent signal generated by the first photoelectric sensor PD1 and the first photocurrent signal generated by the second photoelectric sensor PD2 are The difference between the two photocurrent signals and the photocurrent signal generated by the optical signal received by the second photoelectric sensor PD2 may be equal to or close to the condition.

In one of the embodiments, referring to FIG. 2, the driving processing module 132 includes a driving unit 1321, a timing control unit 1322 and a controller 1323 connected in series. Wherein, the driving unit 1321 is connected to the light-emitting assembly 110, and the controller 1323 is connected to the output end of the transconductance amplifier U module 131. Specifically, the controller 1323 can perform PPG timing settings on the timing control unit 1322, and the driving unit 1321 is configured to drive the light-emitting component 110 according to the PPG timing to emit and turn off light signals in a preset period. It should be noted that the PPG sequence is carried in the driving signal. The light-emitting component 110 may emit and turn off the light signal according to the received driving signal carrying the PPG timing sequence according to a preset period.

Among them, the PPG sequence can be understood as including periodic pulse sequence. For example, the PPG sequence may include a high-level pulse and a low-level pulse, where the high-level pulse and the low-level pulse alternately appear, and the duration of the high-level pulse and the low-level pulse are equal. The light-emitting component 110 emits a light signal when it receives a high-level pulse, and the light-emitting component 110 stops emitting a light signal when it receives a low-level pulse, that is, the emission of the light signal is turned off.

In one of the embodiments, when the first light-emitting unit LED1 emits a light signal under the driving of the driving unit 1321, the PPG test circuit in the foregoing embodiment can correspondingly obtain the corresponding PPG test result. When the light-emitting component 110 turns off the light signal, the first photoelectric sensor PD1 can collect the ambient light signal and output a third photocurrent signal, and the second photoelectric sensor PD2 can also collect the ambient light signal and output the fourth photocurrent signal. At this time, the analog front-end processing component 130 can receive the third photocurrent signal and the fourth photocurrent signal, and calibrate the acquired PPG test result according to the received third photocurrent signal and the fourth photocurrent signal to further calibrate the residual The ambient light is suppressed to obtain more accurate PPG test results. Specifically, when the first light-emitting unit LED1 turns off the light signal, the analog front-end processing component 130 correspondingly acquires the PPG test result under the ambient light condition, and compares the PPG test result under the ambient light condition with the light signal emitted by the first light-emitting unit LED1. The difference calculation of the obtained PPG test results can further suppress the residual ambient light, so as to realize the correction and optimization of the PPG test results, thereby improving the accuracy of the PPG test results.

Optionally, the duration of the first light-emitting unit LED1 emitting the light signal is equal to the duration of the first light-emitting unit LED1 turning off the light signal.

In one of the embodiments, as shown in FIGS. 5 and 6, the light-emitting assembly 110 further includes a first light-emitting unit LED1 and a second light-emitting unit LED2, wherein the first light-emitting unit LED1, the first photoelectric sensor PD1, and the second photoelectric sensor The sensor PD2 and the second light emitting unit LED2 are arranged in a one-dimensional linear array.

Among them, the first light-emitting unit LED1, the first photosensor PD1, and the second photosensor PD2 constitute a first collection circuit; the first photosensor PD1, the second photosensor PD2, and the second light-emitting unit LED2 constitute a second collection circuit. The first distance between the first light-emitting unit LED1 and the second photosensor PD2 is greater than the second distance between the first photosensor PD1 and the second photosensor PD2, and the second distance between the second light-emitting unit LED2 and the first photosensor PD1 The third distance is greater than the second distance.

The analog front-end processing component 130 can periodically control the first acquisition circuit and the second acquisition circuit to be in working state. For example, when the first collection circuit is in working state, that is, the first light-emitting unit LED1 emits light signals, and the second light-emitting unit LED2 turns off the light signals; when the second collection circuit is in working state, that is, the second light-emitting unit LED2 emits light. Signal, and the first light emitting unit LED1 turns off the light signal. It should be noted that the first light-emitting unit LED1 and the second light-emitting unit LED2 do not emit light signals at the same time. For example, driving the first light-emitting unit LED1 to continuously emit light signals for the first duration at the same time, driving the second light-emitting unit LED2 to continuously turn off light signals for the first duration, or driving the first light-emitting unit LED1 to continuously turn off light signals for the first duration at the same time , Driving the second light-emitting unit LED2 to continuously emit the light signal for the first duration.

When the first acquisition circuit is in the working state, the analog front-end processing component 130 can correspondingly acquire the first test result; when the second acquisition circuit is in the working state, the analog front-end processing component 130 can correspondingly acquire the second test result, and the analog front-end processing component 130 may also obtain the PPG test result according to the first test result and the second test result. For example, the analog front-end processing component 130 can average the first test result and the second test result and use the average value as the final PPG test result. The analog front-end processing component 130 can also compare the first test result and the second test result. The optimal test result is screened out, and the screening criterion can be a signal quality factor, which can include a perfusion index, etc., where perfusion index = signal fluctuation part amplitude/signal direct current value.

In the embodiment of the present application, by setting two light-emitting units, a dual-channel PPG acquisition circuit can be formed, that is, a first acquisition circuit and a second acquisition circuit. The dual-channel PPG acquisition circuit is controlled to work together to improve the test accuracy and accuracy of the PPG test results. Accuracy.

In one of the embodiments, the PPG test circuit further includes other sensing modules, wireless transmission modules, positioning modules, etc. connected to the analog front-end processing component 130. Among them, the sensing module may include a temperature sensor, a gyroscope, an acceleration sensor, etc.; the wireless transmission module may include a Bluetooth module, a wifi module, an antenna module, etc., and the positioning module may include a GPS module, a Beidou positioning module, and so on.

Fig. 7 is a flowchart of a PPG test method in an embodiment. As shown in FIG. 3, the PPG test method is applied to the PPG test circuit in any of the above embodiments. The PPG test method includes steps 702 to 706.

Step 702: Drive the light-emitting component to emit light signals.

In one of the embodiments, the analog front-end processing component 130 can drive the light-emitting component 110 to emit light signals. The optical signal may include red light and/or infrared light. Specifically, the light-emitting assembly 110 may include one or more light-emitting units. Each light emitting unit may include one or more light emitting diodes. Specifically, the light emitting diode may be a red light emitting diode (RED LED) or an infrared light emitting diode (IR LED). For example, the light emitting unit may include a red light emitting diode and an infrared light emitting diode at the same time, and the light emitting unit may separately include a red light emitting diode or an infrared light emitting diode.

Step 704: Control the first photoelectric sensor to collect ambient light and output a first photocurrent signal, and control the second photoelectric sensor to collect ambient light and light signals and output a second photocurrent signal, wherein the first photoelectric sensor is connected in parallel with the second photoelectric sensor, Wherein, the luminous fluxes of the optical signals collected by the first photoelectric sensor and the second photoelectric sensor are different.

In one of the embodiments, the first photosensor PD1 and the second photosensor PD2 work in a zero bias state, that is, the first photosensor PD1 and the second photosensor PD2 can both be photodiodes in photovoltaic mode, that is, The first photosensor PD1 is called a first photodiode, and the second photosensor PD2 is called a second photodiode. Specifically, the first photodiode and the second photodiode are in anti-parallel connection, that is, the anode of the first photodiode is connected to the cathode of the second photodiode, and the cathode of the first photodiode is connected to the anode of the second photodiode.

When the light-emitting component 110 emits light signals, the first photoelectric sensor PD1 can be controlled to collect ambient light and light signals and output the first photocurrent signal; and the second photoelectric sensor PD2 can be controlled to collect ambient light and light signals and output the second photocurrent signal .

In one of the embodiments, the light emitting component 110, the first photosensor PD1, and the second photosensor PD2 are arranged in a one-dimensional linear array, and the first distance between the first light emitting unit LED1 and the second photosensor PD2 is greater than the first distance between the first light emitting unit LED1 and the second photosensor PD2. The second distance between the photosensor PD1 and the second photosensor PD2. Wherein, the difference between the first distance and the second distance is between 2 mm and 15 mm. The ambient light 03 is usually parallel light such as sunlight, and the distance between the first photoelectric sensor PD1 and the second photoelectric sensor PD2 is relatively close, so the luminous flux of the ambient light 03 received by the first photoelectric sensor PD1 and the second photoelectric sensor PD2 The difference is within the preset range, and the skin tissue of the user's human body has strong light absorption, so the amount of light emitted by the red LED is collected by the first photoelectric sensor PD1 is much greater than the amount collected by the second photoelectric sensor PD2 , The difference between the first photocurrent signal generated by the first photosensor PD1 and the second photocurrent signal generated by the second photosensor PD2 is equal to the photocurrent signal generated by the optical signal received by the second photosensor PD2. Since the first photosensor PD1 and the second photosensor PD2 are in reverse parallel connection, the photocurrent generated by the ambient light is suppressed.

Wherein, the difference between the luminous flux of the ambient light 03 received by the first photosensor PD1 and the second photosensor PD2 is within a preset range, that is, the luminous flux of the ambient light 03 received by the first photosensor PD1 and the second photosensor The difference of the luminous flux of the ambient light 03 received by the PD2 is within a preset range. Wherein, the preset range can be understood as a range that includes zero and is close to zero. In this application, the preset range is not further limited. For example, when the difference is within the preset range, the first photocurrent signal generated by the first photoelectric sensor PD1 and the first photocurrent signal generated by the second photoelectric sensor PD2 are The difference between the two photocurrent signals and the photocurrent signal generated by the optical signal received by the second photoelectric sensor PD2 may be equal or close to the same condition. Step 706: Perform differential processing and analysis according to the received first photocurrent signal and the second photocurrent signal to obtain a PPG test result.

The first photocurrent signal generated by the first photosensor _{PD1 is} represented by I PD1, and the second photocurrent signal generated by the second photosensor _{PD2 is} represented by I PD2. The analog front-end processing component 130 can output the differential voltage U ₀ _{according to the received first photocurrent signal I PD1} and the second photocurrent signal I _PD2 . Among them, U _o =(I _PD1 -I _PD2 )(R ₁ +R ₂ ), and after filtering, analog-to-digital conversion, integration and other processing of the _{differential voltage U 0, analysis and calculation are performed to obtain the corresponding PPG test result.}

PPG test results can include vital signs information such as pulse heart rate, blood oxygen saturation, blood sugar, blood flow and so on. For example, when red light-emitting diodes or infrared light-emitting diodes are used alone, the PPG test method can detect the reflected light intensity after absorption by human blood and tissues, and calculate the user's heart rate; when red light-emitting diodes and infrared light-emitting diodes are at the same time When used, the PPG test method can detect the reflected light intensity after absorption by human blood and tissues, etc., and can calculate the user's blood oxygen level, blood sugar level and other PPG test results.

In the PPG test method in this embodiment, the first photosensor PD1 can collect ambient light and light signals, and the second photosensor PD2 can collect ambient light and the light signals emitted by the light-emitting component 110. Because the first photosensor PD1 and the second photosensor PD2 is connected in parallel, and the distances between the first photo sensor PD1 and the second photo sensor PD2 and the light emitting component 110 are different. The PPG test method can perform differential processing on the first photocurrent signal output by the first photoelectric sensor PD1 and the second photocurrent signal output by the second photoelectric sensor PD2 to offset the photocurrent signal generated by the ambient light, and does not need to be turned off by control Or turn on the light-emitting component 110 to collect the ambient light in time sharing, and then eliminate the ambient light in the digital domain. A smaller dynamic range can be used, which is beneficial to reduce power consumption, and can also improve the accuracy and accuracy of the PPG test results.

In one of the embodiments, the PPG test method further includes the step of driving the light-emitting component 110 to emit and turn off the light signal according to a preset period according to a preset PPG timing.

Among them, the PPG sequence can be understood as including periodic pulse sequence. For example, the PPG sequence may include a high-level pulse and a low-level pulse, where the high-level pulse and the low-level pulse alternately appear, and the duration of the high-level pulse and the low-level pulse are equal. The light-emitting component 110 emits a light signal when it receives a high-level pulse, and the light-emitting component 110 stops emitting a light signal when it receives a low-level pulse, that is, the emission of the light signal is turned off. The PPG timing sequence may be stored in advance, and the light-emitting component 110 may emit and turn off the light signal according to a preset period according to the received driving signal carrying the PPG timing sequence.

In one of the embodiments, the PPG test method further includes: step 802 to step 804. among them,

Step 802: When the light-emitting component turns off the light signal, control the first photoelectric sensor PD1 to collect ambient light and output a third photocurrent signal, and control the second photoelectric sensor to collect ambient light and output a fourth photocurrent signal;

Step 804: Correct the PPG test result according to the received third photocurrent signal and fourth photocurrent signal.

When the light-emitting component 110 is controlled to turn off the light signal, the first photoelectric sensor PD1 can collect the ambient light signal and output a third photocurrent signal, and the second photoelectric sensor PD2 can collect the ambient light signal and output the fourth photocurrent signal. At this time, the analog front-end processing component 130 can receive the third photocurrent signal and the fourth photocurrent signal, and correspondingly obtain the PPG test result under the ambient light condition according to the received third photocurrent signal and the fourth photocurrent signal. By calculating the difference between the PPG test result under ambient light conditions and the PPG test result obtained when the first light-emitting unit LED1 emits the light signal, the residual ambient light can be further suppressed to realize the correction of the PPG test result Optimization to improve the accuracy of PPG test results.

It should be noted that the duration of the first light-emitting unit LED1 emitting the light signal is equal to the duration of the first light-emitting unit LED1 turning off the light signal.

In one of the embodiments, the light-emitting assembly 110 includes a first light-emitting unit LED1 and a second light-emitting unit LED2. The first light-emitting unit LED1, the first photosensor PD1, the second photosensor PD2, and the second light-emitting unit LED2 are one-dimensional linear. Array settings. Among them, the first light-emitting unit LED1, the first photosensor PD1, and the second photosensor PD2 constitute a first collection circuit; the first photosensor PD1, the second photosensor PD2, and the second light-emitting unit LED2 constitute a second collection circuit.

The PPG test method further includes: driving and controlling the first light-emitting unit LED1 or the second light-emitting unit LED2 to emit light signals; when the first light-emitting unit LED1 emits light signals, obtaining the first PPG test result; when the second light-emitting unit LED2 emits light signals When, obtain the second PPG test result; obtain the PPG test result according to the first PPG test result and the second PPG test result.

Specifically, the analog front-end processing component 130 can periodically control the first collection circuit and the second collection circuit to be in working states. For example, when the first collection circuit is in working state, that is, the first light-emitting unit LED1 emits light signals, and the second light-emitting unit LED2 turns off the light signals; when the second collection circuit is in working state, that is, the second light-emitting unit LED2 emits light. Signal, and the first light emitting unit LED1 turns off the light signal. It should be noted that the first light-emitting unit LED1 and the second light-emitting unit LED2 do not emit light signals at the same time. For example, driving the first light-emitting unit LED1 to continuously emit light signals for the first duration at the same time, driving the second light-emitting unit LED2 to continuously turn off light signals for the first duration, or driving the first light-emitting unit LED1 to continuously turn off light signals for the first duration at the same time , Driving the second light-emitting unit LED2 to continuously emit the light signal for the first duration.

In the embodiment of this application, by setting two light-emitting units, a dual-channel PPG acquisition circuit can be formed, that is, a first acquisition circuit and a second acquisition circuit. The PPG test method can control the dual-channel PPG acquisition circuit to work together to improve the PPG test result The accuracy and accuracy of the test.

It should be understood that although the various steps in the flowcharts of FIGS. 7-8 are displayed in sequence as indicated by the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless there is a clear description in this article, there is no strict order for the execution of these steps, and these steps can be executed in other orders. Moreover, at least part of the steps in Figures 7-8 can include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. These sub-steps or stages The execution order of is not necessarily performed sequentially, but may be performed alternately or alternately with at least a part of other steps or sub-steps or stages of other steps.

The embodiment of the present application also provides a wearable electronic device. Referring to Figures 4, 5, and 7, the wearable electronic device includes a housing and a PPG test circuit. The housing includes an exposed photosensitive detection surface, the light-emitting component 110 and the photosensitive component 120 of the PPG test circuit are both arranged on the photosensitive surface, and the analog front-end processing component 130 of the PPG test circuit is arranged in the housing.

Wherein, the photosensitive detection surface of the housing is the surface in contact with the user's skin. Further, a through hole may be opened on the photosensitive detection surface, and the light-emitting component 110 and the photosensitive component 120 may be disposed at the opening. The light-emitting component 110 and the photosensitive component 120 can contact the user's skin at the opening, transmit light signals to the human body and/or receive light signals fed back by the human body, and then through the analog front-end processing component 130 calculation and processing processes to obtain the human body Health and other related PPG test results.

The above examples only express a few implementation modes of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation to the patent scope of the present application. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of this application, several modifications and improvements can be made, and these all fall within the protection scope of this application. Therefore, the scope of protection of the patent of this application shall be subject to the appended claims.

Claims

A PPG test circuit, which is characterized in that it comprises:

The light-emitting component is used to emit a light signal according to the driving signal;

The photosensitive component includes a first photosensor and a second photosensor connected in parallel, wherein the first photosensor is used for collecting ambient light and the light signal and outputting a first photocurrent signal, and the second photosensor is used for Collecting the ambient light and the light signal and outputting the second photocurrent signal, wherein the light fluxes of the light signals collected by the first photoelectric sensor and the second photoelectric sensor are different;

The analog front-end processing component is respectively connected with the light-emitting component, the first photoelectric sensor and the second photoelectric sensor, and is used to send the driving signal to the light-emitting component, and according to the received first photocurrent signal and the The second photocurrent signal is subjected to differential processing and analysis to obtain the PPG test result.
The PPG test circuit according to claim 1, wherein the first photosensor and the second photosensor are in reverse parallel connection.
The PPG test circuit according to claim 1 or 2, wherein the analog front-end processing component comprises:

Transconductance amplifier module, the negative input end of the transconductance amplifier module is respectively connected to the cathode of the first photoelectric sensor and the anode of the second photoelectric sensor, and the positive input end of the transconductance amplifier module is respectively connected to the cathode of the first photoelectric sensor and the anode of the second photoelectric sensor. The anode of the first photoelectric sensor and the cathode of the second photoelectric sensor are connected for receiving the first photocurrent signal and the second photocurrent signal, and responding to the first photocurrent signal and the second photocurrent signal. Signal differential processing to output differential voltage;

The driving processing module is respectively connected to the output terminal of the transconductance amplifier module and the light-emitting component, and is used to output the driving signal to drive the light-emitting component to emit light, and is also used to obtain the PPG test result according to the differential voltage.
The PPG test circuit according to claim 3, wherein the transconductance amplifier module comprises a transconductance amplifier, a first transconductance resistance, and a second transconductance resistance, and the negative input terminal of the transconductance amplifier is used as the transconductance amplifier. The negative input terminal of the transconductance amplifier module, the positive input terminal of the transconductance amplifier as the positive input terminal of the transconductance amplifier module, and the output terminal of the transconductance amplifier as the transconductance amplifier module Output terminal; where,

The first transconductance resistance is respectively connected to the negative input terminal and the output terminal of the transconductance amplifier, and the second transconductance resistance is respectively connected to the positive input terminal and the output terminal of the transconductance amplifier.
The PPG test circuit according to claim 4, wherein the transconductance amplifier is further used for receiving the first photocurrent signal IPD1, the second photocurrent signal IPD2, the first transconductance resistance R1 and the second transconductance signal IPD2. The conductive resistance R2 is subjected to differential processing to output a differential voltage U 0 ; where U o =(I PD1 -I PD2 )(R 1 +R 2 ).
The PPG test circuit according to claim 3, wherein the drive processing module comprises a drive unit, a timing control unit, and a controller connected in series in sequence, and the controller is used to set the PPG timing of the timing control unit, The driving unit is configured to drive the light-emitting component to emit and turn off the light signal in a preset period according to the PPG timing sequence.
7. The PPG test circuit according to claim 6, wherein the PPG sequence includes a periodic pulse sequence.
The PPG test circuit according to claim 1, wherein:

When the light-emitting component turns off the light signal, the first photoelectric sensor is used to collect the ambient light signal and output a third photocurrent signal, and the second photoelectric sensor is used to collect the ambient light signal, And output the fourth photocurrent signal;

The analog front-end processing component is further configured to correct the PPG test result according to the received third photocurrent signal and the fourth photocurrent signal.
8. The PPG test circuit according to claim 8, wherein the duration of the light signal emitted by the first light-emitting unit is equal to the duration of the light signal being turned off by the first light-emitting unit.
The PPG test circuit according to any one of claims 1-9, wherein the first photoelectric sensor and the second photoelectric sensor have different distances from the light-emitting component.
The PPG test circuit according to claim 10, wherein the light-emitting assembly includes a first light-emitting unit, wherein the first light-emitting unit, the first photoelectric sensor, and the second photoelectric sensor are arranged in an array and form a first light-emitting unit. Collecting circuit, and the first distance between the first light-emitting unit and the second photosensor is greater than the second distance between the first photosensor and the second photosensor.
The PPG test circuit according to claim 11, wherein the light-emitting assembly further comprises a second light-emitting unit, wherein the first photoelectric sensor, the second photoelectric sensor, and the second light-emitting unit are arranged in an array and form a second light-emitting unit. Two collection circuits, and the third distance between the second light-emitting unit and the first photoelectric sensor is greater than the second distance.
The PPG test circuit according to claim 12, wherein the analog front-end processing component is connected to the first light-emitting unit and the second light-emitting unit, and the analog front-end processing component is also used to periodically control the The first collection circuit and the second collection circuit are in a working state, and the PPG test result is obtained according to the first test result output by the first collection circuit and the second test result output by the second collection circuit.
The PPG test circuit according to claim 11, wherein the array is a one-dimensional linear array.
The PPG test circuit according to claim 1, wherein the difference between the luminous flux of the ambient light collected by the first photo sensor and the second photo sensor is within a preset range.
The PPG test circuit of claim 1, wherein the first photoelectric sensor and the second photoelectric sensor work in a zero-bias state.
A PPG test method, which is characterized in that it comprises:

Drive the light-emitting component to emit light signals;

Control the first photoelectric sensor to collect the ambient light and the light signal and output a first photocurrent signal, and control the second photoelectric sensor to collect the ambient light and the light signal and output the second photocurrent signal, wherein the The first photoelectric sensor is connected in parallel with the second photoelectric sensor, wherein the light fluxes of the optical signals respectively collected by the first photoelectric sensor and the second photoelectric sensor are different;

Perform differential processing and analysis according to the received first photocurrent signal and the second photocurrent signal to obtain the PPG test result.
The method according to claim 17, wherein the method further comprises:

The light-emitting component is driven to emit and turn off the light signal according to a preset period according to a preset PPG time sequence.
The method according to claim 18, wherein the method further comprises:

When the light-emitting component turns off the light signal, controlling the first photoelectric sensor to collect ambient light and output a third photocurrent signal, and controlling the second photoelectric sensor to collect ambient light and output a fourth photocurrent signal;

Correcting the PPG test result according to the received third photocurrent signal and the fourth photocurrent signal.
The method according to claim 18, wherein the light-emitting assembly comprises a first light-emitting unit and a second light-emitting unit, and the method further comprises:

Driving and controlling the first light-emitting unit or the second light-emitting unit to emit the light signal;

When the first light-emitting unit emits a light signal, acquiring a first PPG test result;

When the second light-emitting unit emits a light signal, acquiring a second PPG test result;

Acquire the PPG test result according to the first PPG test result and the second PPG test result.
A wearable electronic device, characterized in that it comprises:

The housing, including the exposed photosensitive detection surface;

The PPG test circuit according to any one of claims 1-16, wherein the light-emitting component and the photosensitive component are both arranged on the photosensitive detection surface, and the analog front-end processing component is arranged in the housing.