CN112869720A

CN112869720A - Fingerprint detection device, electronic device, and blood pressure detection method

Info

Publication number: CN112869720A
Application number: CN202110180409.6A
Authority: CN
Inventors: 陈淡生; 汪海翔; 李传林
Original assignee: Shenzhen Goodix Technology Co Ltd
Current assignee: Shenzhen Goodix Technology Co Ltd
Priority date: 2021-02-09
Filing date: 2021-02-09
Publication date: 2021-06-01
Anticipated expiration: 2041-02-09
Also published as: CN112869720B

Abstract

Provided are a fingerprint detection device, an electronic device and a blood pressure detection method, which can facilitate users to carry out all-weather blood pressure monitoring. The fingerprint detection device is suitable for electronic equipment with a display screen, is arranged below the display screen and is used for detecting blood pressure, the electronic equipment comprises a first light source and a second light source, the fingerprint detection device is used for receiving a first light signal which is reflected by a finger of a user and penetrates through the display screen at a first moment, and the first light signal is a light signal with a first wavelength emitted by the first light source; the fingerprint detection device is used for receiving a second optical signal which is reflected by the finger of the user and penetrates through the display screen at a second moment, and the second optical signal is an optical signal with a second wavelength emitted by a second light source; the first wavelength is different from the second wavelength, the first optical signal is used for acquiring a first PPG signal, the second optical signal is used for acquiring a second PPG signal, the first PPG signal and the second PPG signal are used for acquiring a third PPG signal, and the third PPG signal is used for acquiring the blood pressure of the user.

Description

Fingerprint detection device, electronic device, and blood pressure detection method

Technical Field

The present application relates to the field of electronic technologies, and in particular, to a blood pressure detection method and apparatus, and an electronic device.

Background

With the continuous improvement of the current living standard, the proportion of hypertension people is rapidly increased. Currently, the mature blood pressure detection method in the market is a cuff type detection method based on an auscultatory method or an oscillometric method, wherein the auscultatory method requires a professional operator to judge the blood pressure based on the sound of the blood flow of the brachial artery, and is suitable for a medical scene; the oscillography is to inflate the cuff to block the arterial blood flow, then detect the gas pressure in the cuff during the exhaust process and extract the weak pulse wave, and detect the blood pressure value according to the change of the pulse wave along with the pressure in the cuff. For the hypertensive, the accuracy of blood pressure measurement and the portability of the sphygmomanometer are very important, and although the sphygmomanometer adopting the cuff type detection method is accurate in blood pressure measurement, the volume is large, the carrying is inconvenient, the all-weather blood pressure monitoring cannot be carried out, and the requirement of the hypertensive cannot be met. Therefore, how to facilitate the user to perform all-weather blood pressure monitoring becomes an urgent problem to be solved.

Disclosure of Invention

The embodiment of the application provides a fingerprint detection device, electronic equipment and a blood pressure detection method, which can facilitate all-weather blood pressure monitoring for a user.

In a first aspect, a fingerprint detection device is provided, which is suitable for an electronic device having a display screen, and is disposed below the display screen and used for performing blood pressure detection, where the electronic device includes a light source including a first light source and a second light source, where the fingerprint detection device is configured to receive a first optical signal reflected by a finger of a user and passing through the display screen at a first time, and the first optical signal is an optical signal with a first wavelength emitted by the first light source; the fingerprint detection device is used for receiving a second optical signal which is reflected back by the finger of the user and penetrates through the display screen at a second moment, and the second optical signal is an optical signal with a second wavelength emitted by the second light source; wherein the first wavelength is different from the second wavelength, the first optical signal is used to acquire a first PPG signal, the second optical signal is used to acquire a second PPG signal, the first PPG signal and the second PPG signal are used to acquire a third PPG signal, and the third PPG signal is used to acquire the blood pressure of the user.

In a second aspect, an electronic device is provided, which includes a display screen and the fingerprint detection apparatus according to the first aspect, wherein the fingerprint detection apparatus is disposed below the display screen for performing blood pressure detection.

In a third aspect, a blood pressure detecting method is provided, which includes:

at a first moment, a fingerprint detection device receives a first optical signal which is reflected by a finger of a user and passes through a display screen, wherein the first optical signal is an optical signal with a first wavelength emitted by a first light source and is used for acquiring a first PPG signal; at a second moment, the fingerprint detection device receives a second optical signal which is reflected by the finger of the user and passes through the display screen, wherein the second optical signal is an optical signal with a second wavelength emitted by the second light source and is used for acquiring a second PPG signal; obtaining a third PPG signal according to the first PPG signal and the second PPG signal, wherein the third PPG signal is used for obtaining the blood pressure of the user, and the first wavelength is different from the second wavelength.

In the embodiment that this application provided, adopt fingerprint detection device under the screen to acquire the PPG signal, further acquire user's blood pressure, because the electronic equipment volume of carrying fingerprint detection device under the screen is less portable, therefore can convenience of customers carry out all-weather blood pressure detection. In addition, the light sources with at least two different wavelengths are used for obtaining the PPG signals with different wavelengths, and the PPG signals with at least two different wavelengths are further used for obtaining the PPG signals closer to deep blood vessels, so that the finally obtained blood pressure is closer to a real value. Besides, the fingerprint detection device has a fingerprint detection function and is also used for detecting blood pressure, so that a blood pressure detection device does not need to be additionally arranged, and the cost of the electronic equipment can be greatly reduced.

Drawings

Fig. 1 is a schematic structural diagram of an electronic device to which the fingerprint detection apparatus provided in the embodiment of the present application is applied.

Fig. 2 is a schematic cross-sectional view of an electronic device to which the fingerprint detection device provided in the present application is applied.

Fig. 3 is a schematic view of the transverse arch artery of the finger.

FIG. 4 is a schematic diagram of a tangent method for obtaining whether a pressing area of a finger pressing a display screen contains a fingerprint center according to a fingerprint image.

Fig. 5 is a schematic flow chart block diagram of a blood pressure detection method according to an embodiment of the present application.

Fig. 6 is a schematic flow chart diagram of another blood pressure detection method provided in the embodiment of the present application.

Fig. 7 is a schematic flow chart diagram of another blood pressure detection method provided in the embodiment of the present application.

Fig. 8 is a schematic flow chart diagram of another blood pressure detection method provided in the embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

It should be understood that the specific examples are provided herein only to assist those skilled in the art in better understanding the embodiments of the present application and are not intended to limit the scope of the embodiments of the present application.

It should also be understood that, in the various embodiments of the present application, the sequence numbers of the processes do not mean the execution sequence, and the execution sequence of the processes should be determined by the functions and the inherent logic of the processes, and should not constitute any limitation to the implementation process of the embodiments of the present application.

It should also be understood that the various embodiments described in this specification can be implemented individually or in combination, and the examples in this application are not limited thereto.

Unless otherwise defined, all technical and scientific terms used in the examples of this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the present application is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In order to meet the requirements of users and facilitate all-weather blood pressure detection of the users so as to monitor the health condition of the body at any time, the application provides a fingerprint detection device which is suitable for an electronic device with a display screen, the fingerprint detection device is arranged below the display screen and used for detecting the blood pressure, the electronic device comprises a light source, the light source comprises a first light source and a second light source, the fingerprint detection device is used for receiving a first light signal which is reflected by a finger of the user and passes through the display screen at a first moment, and the first light signal is a light signal with a first wavelength sent by the first light source;

the fingerprint detection device is used for receiving a second optical signal which is reflected back by the finger of the user and penetrates through the display screen at a second moment, and the second optical signal is an optical signal with a second wavelength emitted by the second light source;

wherein the first wavelength is different from the second wavelength, the first optical signal is used to acquire a first PPG signal, the second optical signal is used to acquire a second PPG signal, the first PPG signal and the second PPG signal are used to acquire a third PPG signal, and the third PPG signal is used to acquire the blood pressure of the user.

In the embodiment that this application provided, adopt fingerprint detection device under the screen to acquire Photoplethysmography (PPG) signal, further acquire user's blood pressure, because the electronic equipment volume of carrying fingerprint detection device under the screen is less portable, therefore can make things convenient for the user to carry out all-weather blood pressure detection. In addition, the light sources with at least two different wavelengths are used for obtaining the PPG signals with different wavelengths, and the PPG signals with at least two different wavelengths are further used for obtaining the PPG signals closer to deep blood vessels, so that the finally obtained blood pressure is closer to a real value. Besides, the fingerprint detection device has a fingerprint detection function and is also used for detecting blood pressure, so that a blood pressure detection device does not need to be additionally arranged, and the cost of the electronic equipment can be greatly reduced.

Fig. 1 is a schematic view of an electronic device to which a fingerprint detection apparatus according to an embodiment of the present disclosure is applied, and fig. 2 is a sectional view of the electronic device shown in fig. 1. The electronic device 100 comprises a fingerprint detection device 101 and a display screen 102, wherein the fingerprint detection device 101 is arranged below the display screen 102 and is used for detecting blood pressure. Specifically, the fingerprint detection device 101 may be disposed below a fingerprint detection area (not shown in fig. 1) of the display screen 102 for acquiring fingerprint information of a finger or blood pressure information of a user. Optionally, the electronic device 100 may further include a protective cover 103, where the protective cover 103 is disposed above the display screen 102 to protect the display screen, and specifically, the protective cover 103 may be a glass cover or a sapphire cover, and the like.

The fingerprint detection device 101 comprises an array of pixel units (not shown in fig. 1) comprising a plurality of pixel units for receiving an optical signal and converting it into a corresponding electrical signal, e.g. a PPG signal, a pixel of a fingerprint image.

The electronic device 100 includes a light source, which may be a light emitting pixel 1021 of a display screen 102, the display screen 102 being a self-emissive display screen, such as an OLED display screen. At the moment, the luminous pixels of the display screen can be directly used as an excitation light source for blood pressure detection or fingerprint detection, additional light sources are not needed, the cost can be reduced, in addition, the luminous pixels of the display screen are used as the excitation light source, the light emission is more uniform, and more accurate blood pressure values can be obtained or fingerprint detection results are more accurate. The light-emitting pixels of the OLED display screen comprise red, blue and green light-emitting pixels and can be used as an excitation light source for blood pressure detection or fingerprint detection. When blood pressure detection is performed, different light sources can be subjected to time-sharing light-striking, as described above, light sources with different wavelengths can be adopted to emit light at the first moment and the second moment, the fingerprint detection device 101 receives light signals emitted by corresponding light sources at the first moment and the second moment, and the light sources with different wavelengths are subjected to time-sharing light-striking, so that a PPG signal closer to a deep blood vessel can be further obtained, and the finally obtained blood pressure is closer to a true value. When carrying out fingerprint detection, can only adopt the light source of a certain colour or a certain wavelength to polish, also can adopt the light source of multiple colour or multiple wavelength to polish simultaneously, because fingerprint detection mainly detects the valley ridge way information that the user pointed, need not to acquire deep vascular information, only adopts a certain colour to polish, perhaps adopts the light source of multiple colour to polish simultaneously, can further promote fingerprint detection's efficiency, promotes user experience. It can be understood that, when the fingerprint detection apparatus is applied to an electronic device having a non-self-luminous display screen, a light source may be additionally disposed, and the light source is disposed below the display screen or disposed side by side with the display screen, which is not limited in the embodiments of the present application. It will be appreciated that light sources of different colors emit light of different wavelengths.

Optionally, the first light source is a red light source, and the second light source is a blue light source or a green light source. Referring to fig. 2, assuming that the red light source is a red light-emitting pixel in the display screen 102, because red light has a strong penetrating capability and can reach deep blood vessels, in other words, when red light is reflected by a finger and reaches the fingerprint detection device, or reaches the pixel unit array of the fingerprint detection device 101, the red light carries information of both deep blood vessels and shallow blood vessels, so that PPG signals of both deep blood vessels and shallow blood vessels can be captured simultaneously by using red light, for example, after the red light-emitting pixel emits a light signal 105 and is reflected by a finger 200, a light signal 106 and a light signal 107 carry information of both shallow blood vessels and deep blood vessels, respectively, where 201 is a deep blood vessel of the finger, for example, a transverse arch artery of the palm. The green light or the blue light has weak penetrating power and can only reach superficial blood vessels (not shown in fig. 2), such as epidermal capillaries, in other words, when the green light or the blue light is reflected by the finger and reaches the fingerprint detection device, or reaches the pixel unit array of the fingerprint detection device 101, the green light or the blue light only carries information of the superficial blood vessels, so that the green light or the blue light can only obtain the PPG signals of the superficial blood vessels, and therefore the PPG signals of the deep blood vessels, i.e. the third PPG signals, can be calculated by the first PPG signals and the second PPG signals.

Optionally, the third PPG signal may be obtained by subtracting the first PPG signal and the second PPG signal, i.e., the third PPG signal is the difference between the first PPG signal and the second PPG signal, or by normalizing the first PPG signal and the second PPG signal. Thereby further enabling to obtain a blood pressure closer to the true value from the third PPG signal carrying the deep blood vessel information.

As an alternative embodiment, the fingerprint detection apparatus 101 further comprises a processor (not shown in fig. 2) for acquiring a third PPG signal from the first and second PPG signals. Specifically, the processor is configured to obtain the third PPG signal by subtracting the first PPG signal and the second PPG signal, or the processor is configured to obtain the third PPG signal by normalizing the first PPG signal and the second PPG signal.

Further, the processor is further configured to obtain a blood pressure of the user from the third PPG signal.

In order to be applied to wearable devices, the frequency of daily blood pressure tests of hypertensive patients is increased, smart watches manufactured based on Pulse Transit Time (PTT) and Pulse Wave Analysis (PWA) methods are on the market, and blood pressure is indirectly acquired by calculating Pulse Wave transmission speed or analyzing Pulse Wave waveforms through Electrocardiograms (ECGs) and PPG signals on the smart watches. PTT refers to the time it takes for an arterial pulse wave to reach the surrounding blood vessels from the aortic valve when the heart pumps blood, which has a positive correlation with blood pressure and thus can be used for blood pressure detection. PWA means that information such as the shape, amplitude, and time and peak of a pulse wave waveform has a certain correlation with blood vessel elasticity and blood pressure, and thus can be used for blood pressure detection. However, these solutions all acquire blood pressure in an indirect manner, so the measurement accuracy is poor.

In the embodiment provided by the present application, the fingerprint detection device 101 is further configured to obtain the blood pressure of the user according to the third PPG signal and the pressing pressure of the finger of the user on the display screen 102, so as to improve the accuracy of blood pressure detection.

The information that the pressing pressure contains the pressure dimension can improve the accuracy of blood pressure detection. The blood pressure statistics of the population is 40 mmHg-200 mmHg, 200mmHg can be used as a condition for judging the end of collection, and in addition, when the finger pressing pressure is greater than 200mmHg, the finger blood flow is blocked, and a PPG signal disappears, so the judgment can be also carried out according to the amplitude of the PPG signal. And when the amplitude of the PPG signal is lower than a certain set value, ending the PPG signal acquisition.

As an alternative embodiment, the acquisition of the first or second PPG signal is ended when the compression pressure is equal to or above a third threshold. The third threshold is 200 mmHg. Or ending the acquisition of the first/second PPG signals when the amplitude of the first/second PPG signals is less than a fourth threshold.

The fingerprint detection device 102 may be configured to obtain a pressing pressure of the user's finger on the display screen 102 according to a pressing area of the user's finger on the display screen 102 and a pressing pressure of the user's finger on the display screen 102, where the pressing area of the user's finger on the display screen 102 is obtained through the fingerprint detection device 101 or the display screen 102.

As an alternative embodiment, referring to fig. 1 and 2, the electronic device 100 further comprises a pressure sensor 104, and the pressure sensor 104 is disposed below the display screen 102 adjacent to the fingerprint recognition device 101. The pressure sensor 104 is disposed adjacent to the fingerprint identification device 101, so that when the user finger 200 presses the display screen 102 to perform blood pressure detection, and when the fingerprint detection device 101 acquires a PPG signal, the pressure sensor 104 can be used to acquire the pressing pressure of the user finger 200 pressing the display screen 102, and therefore the pressing pressure of the user finger 200 during blood pressure detection can be further obtained according to the pressing area and the pressing pressure. When the fingerprint detection device 101 acquires the PPG signal, the pressing pressure of the user finger pressing the display screen 102 can be acquired through the pressure sensor 104, and therefore, after the pressing pressure is further acquired, more accurate blood pressure can be acquired through the pressing pressure and the third PPG signal.

As an alternative embodiment, the fingerprint detection device 101 is further configured to obtain a pressing area of the user's finger 200 on the display screen 102. When the finger 200 of the user presses the upper side of the fingerprint detection area of the display screen 102, the fingerprint detection device 101 is configured to receive the light signal that the light source irradiates the finger of the user, and the light signal passes through the display screen 102 after being reflected by the finger of the user, so as to further obtain the pressing area of the finger 200 of the user on the display screen 102. When the light source is the light-emitting pixel 1021 of the display screen 102, a light signal emitted by the light-emitting pixel 1021 irradiates the user finger 200, is reflected by the surface of the finger, and is received by the fingerprint detection device 101, so as to obtain a pressing area of the user finger pressing on the display screen 102. For example, the display screen is an OLED display screen, and the light-emitting pixels corresponding to the fingerprint detection area all emit light, and the light-emitting pixels may include red, blue and green light-emitting pixels, which can be used as an excitation light source for acquiring the pressing area.

As a specific embodiment, the fingerprint detection device receives an optical signal reflected by the surface of the user's finger to form a fingerprint image, the fingerprint image is processed to obtain the pressing area of the user's finger 200 on the display screen 102, and the optical signal is emitted by the light source. In particular, the processor of the fingerprint detection device 101 may be configured to process the fingerprint image to obtain the pressing area.

As another alternative, the display screen 102 is used to obtain the pressing area of the user's finger 200 on the display screen 102. For example, the display screen is a touch-control integrated display screen having a touch-control function, and at this time, the pressing area of the user's finger 200 on the display screen 102 can be obtained through the touch-control function. In this case, it is not necessary to form a fingerprint image by the fingerprint detection device 101 and acquire the pressing area, and the flow can be reduced and the efficiency of blood pressure detection can be improved.

It is understood that the pressure sensor 104 can measure the time-varying value of the pressing pressure, and thus the time-varying value of the pressure can be obtained by combining the pressing areas.

In order to obtain a more accurate blood pressure of the user, optionally, the processor is further configured to sort, from large to small, third PPG signals respectively acquired by a plurality of pixel units of the fingerprint detection apparatus according to the strength of the third PPG signals.

Optionally, the processor is further configured to retain the sorted third PPG signals, where a permutation number of the third PPG signals is less than or equal to a first threshold, where the first threshold is a ratio of the permutation number of the third PPG signals to the number of the third PPG signals. For convenience of description, the third PPG signal with the ranking number less than or equal to the first threshold value in the third PPG signals after the sorting is reserved is referred to as the fourth PPG signal. For example, the first threshold may be 30%, 25%, or 20%. If the light source does not irradiate the deep blood vessel, the obtained third PPG signal is weak, in order to further improve the accuracy of blood pressure detection, the third PPG signal with the intensity smaller than the first threshold value according to the ranking sequence of the intensity sorted from large to small can be reserved, namely the third PPG signal with the intensity larger is reserved, and therefore a more accurate blood pressure value can be obtained through the screened third PPG signal with the intensity larger (namely the fourth PPG signal). For example, if there are 400 third PPG signals currently, the 400 third PPG signals are sorted according to their intensities from large to small, if the first threshold is 30%, the third PPG signals before the permutation number 120 are retained, that is, the third PPG signals with the permutation order of 1 to 120 are retained, that is, the first 120 third PPG signals are retained, and the 120 third PPG signals are denoted as the fourth PPG signals, it can be understood that if the product of the number of the third PPG signals and the first threshold is not an integer, it can be determined whether to retain the current third PPG signal according to a rounding method. The third PPG signals with the arrangement sequence being larger than the first threshold value are discarded, so that the measurement of the blood pressure is not influenced, and a more accurate blood pressure value can be obtained.

Optionally, the processor is configured to obtain a compression pressure at a time when a peak-to-peak value of the fourth PPG signal is maximum according to the fourth PPG signal and the compression pressure, and obtain the blood pressure of the user according to the compression pressure at the time when the peak-to-peak value of the fourth PPG signal is maximum.

Optionally, the processor is configured to sequence fourth PPG signals respectively obtained by a plurality of pixel units in the fingerprint detection device according to the compression pressure, so as to obtain a fourth PPG signal envelope. For example, the processor is configured to sort the fourth PPG signals respectively acquired by the plurality of pixel units from large to small according to the compression pressure.

Optionally, the processor is further configured to retain the fourth PPG signals (fourth PPG signal envelopes) with permutation numbers smaller than or equal to a second threshold in the sorted fourth PPG signals, where the second threshold is a ratio of permutation numbers of the fourth PPG signals to the number of the fourth PPG signals. For convenience of description, a signal with an array number smaller than or equal to a second threshold value in the fourth PPG signal (fourth PPG signal envelope) after the retention of the ordering is referred to as a fifth PPG signal. For example, the second threshold may be 30%, 25% or 20%. The larger the pressure corresponding to the fourth PPG signal envelope peak is, the more deep aorta signals acquired by the pixel unit are represented. Therefore, the accuracy of blood pressure detection can be further improved by further screening out the fourth PPG signal which is less than or equal to the second threshold value. For example, if there are currently 120 fourth PPG signals, the 120 fourth PPG signals are sorted according to the compression pressure from large to small to obtain the fourth PPG signal envelope, and if the second threshold is 30%, the fourth PPG signals before the arrangement number 36 are retained, that is, the fourth PPG signals with the arrangement order of 1 to 36 are retained, that is, the first 36 fourth PPG signals are retained, and it can be understood that if the product of the number of the fourth PPG signals and the second threshold is not an integer, it can be determined whether to retain the current fourth PPG signal according to a rounding method. Because the information carried by the fourth PPG signal with the arrangement sequence being positioned in front is closer to the aorta in the body, the fourth PPG signal with the arrangement sequence being larger than the second threshold value is discarded, the measurement of the blood pressure is not influenced, and a more accurate blood pressure value can be obtained.

Furthermore, if the isolated pixel units with large position deviations, which may be signal interference, such as sympathetic nerve activity, are directly discarded, the fifth PPG signal acquired by the isolated pixel unit corresponding to the adjacent pixel unit in the fingerprint detection device may also be discarded or rejected. For convenience of description, after discarding or removing the fifth PPG signal corresponding to the isolated pixel unit, the remaining fifth PPG signal is referred to as the sixth PPG signal. Since the transverse arch artery is a blood vessel with a band-shaped distribution and has a certain width, the pixel units corresponding to the fifth PPG signal retained in the previous step, i.e. the sixth PPG signal, should be band-shaped. And performing blood pressure calculation by using the PPG signals obtained by the pixel units of the part to obtain the blood pressure which is closer to the blood pressure of the aorta in vivo. The sixth PPG signal envelope formed according to the retained sixth PPG signal is further analyzed, the mean arterial pressure of the user can be obtained, and then the blood pressure value can be calculated according to a coefficient method or a double gaussian fitting method. Wherein, the mean arterial pressure may be a pressure corresponding to the sixth PPG signal envelope peak.

Fig. 4 is a schematic view of a finger 200, wherein the finger 200 includes a transverse arch artery 201, which can be seen together with fig. 2. The blood pressure value of the transverse arch artery of the finger is closer to the blood pressure value of the aorta in the body than the other arterioles, the thickness of the transverse arch artery of the finger is 0.85 ± 0.1mm, and the length is close to the finger width, and since the transverse arch artery of the finger is located near the fingerprint center position of the finger, in order to obtain a more accurate blood pressure value, the fingerprint detection device 101 determines whether the pressing area of the finger includes the fingerprint center after obtaining the fingerprint image, and if the finger pressing position is deviated, such as fingertip pressing or edge pressing, the obtained fingerprint image does not include the fingerprint center, such pressing position does not include the transverse arch artery of the finger, and thus an accurate blood pressure value cannot be obtained in the blood pressure detection. Specifically, whether the fingerprint image contains the fingerprint center may be determined by the processor of the fingerprint detection apparatus 101. Referring to fig. 4, a tangent method may be used to confirm whether the current fingerprint image contains a fingerprint center. Specifically, two non-parallel fingerprint lines can be found on the fingerprint image at will, tangent lines are respectively made on the two fingerprint lines, if the focal points of the two normal lines are located in the fingerprint image, the pressing area representing the finger contains the fingerprint center, and if the focal points of the two normal lines are located outside the fingerprint image, the pressing area representing the finger does not contain the fingerprint center.

As an alternative embodiment, if it is determined that the pressing area of the finger does not include the fingerprint center, the blood pressure detection is ended, and the user may be prompted to press again until it is determined that the pressing area of the finger includes the fingerprint center.

As an alternative embodiment, if it is determined that the pressing area of the finger includes the center of the fingerprint, the blood pressure detection is continued. As can be seen from the foregoing, the first light source and the second light source are illuminated, and the fingerprint detection device 101 acquires the first PPG signal and the second PPG signal. Alternatively, only the light-emitting pixels in the rectangular range with the fingerprint center as the center, the width of R and the length of S in the orthographic projection of the fingerprint center on the display screen can be lightened to further reduce the power consumption in the blood pressure detection, wherein the width direction is along the length direction of the fingers, the length direction is the width direction of the fingers, referring to the rectangle 202 shown in fig. 3, the transverse arch artery near the center of the fingerprint can be sufficiently irradiated according to the light-up area shown by the rectangle 202, considering that the positions of the transverse arch artery of the palm of different people are scattered within the range of + -1 mm from the center of the fingerprint, optionally, R is less than or equal to 3mm, S is greater than or equal to the width of the finger, for example, S is greater than or equal to 8mm, which not only ensures that the light-emitting pixels can irradiate the area where the transverse arch artery is located, but also reduces power consumption of the electronic device when performing blood pressure detection.

In the embodiment of the present application, the blood pressure detection may be performed by the processor, for example, the processor may perform various signal processing of blood pressure detection.

The embodiment of the application further provides electronic equipment, which comprises a display screen and a fingerprint detection device, wherein the fingerprint detection device is arranged below the display screen and used for detecting blood pressure. Specifically, the fingerprint detection device may be disposed below a fingerprint detection area of the display screen, and configured to acquire fingerprint information of a finger or blood pressure information of a user.

The electronic equipment further comprises a pressure sensor, and the pressure sensor and the fingerprint identification device are adjacently arranged below the display screen. Pressure sensor and fingerprint identification device are adjacent to be set up, can make the user's finger press and carry out blood pressure detection at the display screen time for fingerprint detection device is when acquireing PPG signal, and pressure sensor can be used for acquireing the pressure that the user's finger pressed the display screen, therefore acquires more accurate blood pressure. The electronic equipment can be mobile electronic equipment such as a mobile phone and a tablet personal computer.

The electronic device may further include a light source, and please refer to the related contents of fig. 1 and fig. 2 for related contents of the electronic device, which is not described herein again.

Fig. 5 shows a blood pressure detection method according to an embodiment of the present application, where the blood pressure detection method includes:

s501, at a first moment, a fingerprint detection device receives a first optical signal which is reflected by a finger of a user and penetrates through a display screen, wherein the first optical signal is an optical signal with a first wavelength emitted by a first light source and is used for acquiring a first PPG signal;

s502, at a second moment, the fingerprint detection device receives a second optical signal which is reflected back by a finger of a user and penetrates through the display screen, wherein the second optical signal is an optical signal with a second wavelength emitted by the second light source and is used for acquiring a second PPG signal;

s503, acquiring a third PPG signal according to the first PPG signal and the second PPG signal, wherein the third PPG signal is used for acquiring the blood pressure of the user, and the first wavelength is different from the second wavelength.

The blood pressure detection method of the embodiment of the application is suitable for the fingerprint detection device shown in fig. 1 and fig. 2 or the electronic device, and the fingerprint detection device has a detection function and is also used for detecting blood pressure, so that a blood pressure detection device does not need to be additionally arranged, and the cost of the electronic device can be greatly reduced. The relevant contents can be referred to the contents described in fig. 1 to 4, and are not described in detail here.

Before starting the blood pressure detection, the user may be guided to place a finger in the fingerprint detection area of the display screen. The fingerprint detection device may be disposed below a fingerprint detection area of the display screen, and configured to acquire fingerprint information of a finger or blood pressure information of a user.

According to the blood pressure detection method, the under-screen fingerprint detection device is adopted to obtain the PPG signal, the blood pressure of the user is further obtained, and the electronic equipment carrying the under-screen fingerprint detection device is small in size and convenient to carry, so that the user can conveniently carry out all-weather blood pressure detection. In addition, the light sources with at least two different wavelengths are used for obtaining the PPG signals with different wavelengths, and the PPG signals with at least two different wavelengths are further used for obtaining the PPG signals closer to deep blood vessels, so that the finally obtained blood pressure is closer to a real value.

The display screen in the embodiment of the application can be self-luminous display screen, for example, OLED display screen, and first light source and second light source can be the light emitting pixel of display screen, and at this moment, can directly utilize the light emitting pixel of display screen as the excitation light source of blood pressure detection or fingerprint detection, need not additionally to increase the light source, can reduce cost, in addition, utilize the light emitting pixel of display screen as the excitation light source, it is more even to give out light, can obtain more accurate blood pressure value or make the fingerprint detection result more accurate. The light-emitting pixels of the OLED display screen comprise red, blue and green light-emitting pixels and can be used as an excitation light source for blood pressure detection or fingerprint detection. When blood pressure detection is carried out, different light sources can be subjected to time-sharing light-striking, as described above, light sources with different wavelengths can be adopted to emit light at the first moment and the second moment, the fingerprint detection device receives light signals emitted by the corresponding light sources at the first moment and the second moment, and the light sources with different wavelengths are subjected to time-sharing light-striking, so that a PPG signal closer to a deep blood vessel can be further obtained, and finally the obtained blood pressure is closer to a true value. When carrying out fingerprint detection, can only adopt the light source of a certain colour or a certain wavelength to polish, also can adopt the light source of multiple colour or multiple wavelength to polish simultaneously, because fingerprint detection mainly detects the valley ridge way information that the user pointed, need not to acquire deep vascular information, only adopts a certain colour to polish, perhaps adopts the light source of multiple colour to polish simultaneously, can further promote fingerprint detection's efficiency, promotes user experience. It can be understood that, when the fingerprint detection apparatus is applied to an electronic device having a non-self-luminous display screen, a light source may be additionally disposed, and the light source is disposed below the display screen or disposed side by side with the display screen, which is not limited in the embodiments of the present application. It will be appreciated that light sources of different colors emit light of different wavelengths.

Optionally, the first light source is a red light source, and the second light source is a blue light source or a green light source. Because the red light has strong penetrating power and can reach deep blood vessels, in other words, when the red light is reflected by a finger and reaches the fingerprint detection device, or reaches the pixel unit array of the fingerprint detection device, the red light carries the information of the deep blood vessels and the superficial blood vessels simultaneously, and therefore the PPG signals of the deep blood vessels and the superficial blood vessels can be captured simultaneously by the red light. The green light or the blue light has weak penetrating power and can only reach shallow blood vessels, such as epidermal capillaries, in other words, when the green light or the blue light is reflected by the finger and reaches the fingerprint detection device, or reaches the pixel unit array of the fingerprint detection device, the green light or the blue light only carries information of the shallow blood vessels, so that the green light or the blue light can only obtain the PPG signals of the shallow blood vessels, and therefore the PPG signals obtained by the deep blood vessels, i.e. the third PPG signals, can be calculated by the first PPG signals and the second PPG signals.

The "acquiring a third PPG signal from the first and second PPG signals" in S503 comprises: obtaining a third PPG signal by subtracting the first PPG signal and the second PPG signal; or normalizing the first PPG signal and the second PPG signal to acquire the third PPG signal.

Referring to fig. 6, the blood pressure detecting method further includes:

s504: and acquiring the pressing pressure of the finger of the user pressing the display screen, and acquiring the blood pressure of the user according to the third PPG signal and the pressing pressure.

Referring to fig. 7, in the blood pressure detecting method S504, the obtaining the pressing pressure of the user' S finger pressing the display screen includes:

s5041: and acquiring the pressing pressure of the user finger on the display screen according to the pressing area of the user finger on the display screen and the pressing pressure of the user finger on the display screen, wherein the pressing area of the user finger on the display screen is acquired through the fingerprint detection device or the display screen.

Optionally, the pressing pressure of the finger of the user on the display screen may be obtained through a pressure sensor, and the pressure sensor may be disposed below the display screen adjacent to the fingerprint detection device. During blood pressure detection, the fingerprint detection device can acquire the pressing pressure of pressing the display screen by a finger of a user through the pressure sensor when acquiring a PPG signal, so that more accurate blood pressure can be acquired through the pressing pressure and the third PPG signal after the pressing pressure is further acquired.

Optionally, the pressing area of the user's finger on the display screen may be acquired by the fingerprint detection device. When a user finger presses the upper side of a fingerprint detection area of the display screen, the fingerprint detection device is used for receiving the light source irradiating the user finger and passing through the optical signal of the display screen after being reflected by the user finger, so that the pressing area of the display screen of the user finger can be obtained. When the light source is the luminous pixel of the display screen, the light signal emitted by the luminous pixel irradiates the finger of the user, is reflected by the surface of the finger and is received by the fingerprint detection device, and then the pressing area of the finger of the user pressed on the display screen is obtained. For example, the display screen is an OLED display screen, and the light-emitting pixels corresponding to the fingerprint detection area all emit light, and the light-emitting pixels may include red, blue and green light-emitting pixels, which can be used as an excitation light source for acquiring the pressing area.

As a specific embodiment, the fingerprint detection device receives an optical signal reflected by a surface of a finger of a user to form a fingerprint image, the fingerprint image is processed to obtain a pressing area of the finger of the user pressing on the display screen, and the optical signal is emitted by the light source. In particular, the processor of the fingerprint detection device may be configured to process the fingerprint image to obtain the pressing area.

The method for detecting blood pressure, in which the blood pressure value of the transverse arch artery of the finger is closer to the blood pressure value of the aorta in the body than the other arterioles, the thickness of the transverse arch artery of the finger is 0.85 ± 0.1mm, and the length of the transverse arch artery of the finger is close to the width of the finger, and the transverse arch artery of the finger is located near the center of the fingerprint of the finger, includes the steps of:

the fingerprint detection device forms a fingerprint image according to the received optical signal reflected by the surface of the user finger;

judging whether the pressing area of the finger of the user contains a fingerprint center or not according to the fingerprint image;

if the pressing area of the finger of the user does not contain the fingerprint center, ending the blood pressure detection;

and if the pressing area of the finger contains the fingerprint center, continuing to detect the blood pressure.

As an alternative embodiment, if it is determined that the pressing area of the finger of the user does not include the fingerprint center, the user may be prompted to press again until it is determined that the pressing area of the finger of the user includes the fingerprint center.

It is understood that if the finger pressing position is deviated, for example, a fingertip pressing or a finger edge pressing, the fingerprint image obtained at this time does not include the center of the fingerprint, and such a pressing position does not include the transverse arch artery of the finger, so that an accurate blood pressure value cannot be obtained when performing blood pressure detection.

"judging whether the pressing area of the finger of the user contains the fingerprint center according to the fingerprint image" includes: and judging whether the pressing area of the finger of the user contains the fingerprint center by adopting a tangent line method. Specifically, two non-parallel fingerprint lines can be found on the fingerprint image at will, tangent lines are respectively made on the two fingerprint lines, if the focal points of the two normal lines are located in the fingerprint image, the pressing area representing the finger of the user contains the fingerprint center, and if the focal points of the two normal lines are located outside the fingerprint image, the pressing area representing the finger does not contain the fingerprint center.

As an alternative embodiment, if it is determined that the pressing area of the finger includes the center of the fingerprint, the blood pressure detection is continued. As can be seen from the foregoing, the first light source and the second light source are illuminated, and the fingerprint detection apparatus acquires the first PPG signal and the second PPG signal. Optionally, the power consumption during blood pressure detection may be further reduced by lighting only the light-emitting pixels within a rectangular range having an orthogonal projection of the fingerprint center on the display screen as a center, a width of R, and a length of S, where the width direction is a direction along the length of the finger, and the length direction is a direction of the finger width, and the light-emitting pixels may refer to the rectangle 202 shown in fig. 3, and according to the lighting area shown by the rectangle 202, the transverse arch artery near the fingerprint center can be fully illuminated, and considering that the position dispersion of the transverse arch artery of different people is within a range of ± 1mm of the fingerprint center, optionally, R is less than or equal to 3mm, and S is greater than or equal to the width of the finger, for example, S is greater than or equal to 8mm, which not only ensures that the light-emitting pixels can illuminate the area where the transverse arch artery is located, but also reduces the power consumption during blood pressure detection.

As another alternative embodiment, the display screen is used for acquiring the pressing area of the finger of the user on the display screen. For example, the display screen is a touch integrated display screen with a touch function, and at this time, the pressing area of the finger of the user on the display screen can be acquired through the touch function. In this case, it is not necessary to form a fingerprint image by a fingerprint detection device and acquire the pressing area, and the flow can be reduced and the efficiency of blood pressure detection can be improved.

It is understood that the pressure sensor can measure the time-varying value of the pressing pressure, and thus the time-varying value of the pressure can be obtained by combining the pressing areas.

In order to get a more accurate blood pressure of the user, the "obtaining a blood pressure of the user from the third PPG signal and the compression pressure. "comprises:

s5042: sorting third PPG signals respectively acquired by a plurality of pixel units in the fingerprint detection device from big to small according to the intensity of the third PPG signals, and reserving the signals with the sequence numbers smaller than or equal to a first threshold value in the sorted third PPG signals, wherein the first threshold value is the ratio of the sequence numbers of the third PPG signals to the number of the third PPG signals, and the third PPG signals with the sequence numbers smaller than or equal to the first threshold value are fourth PPG signals.

The first threshold may be 30%, 25% or 20%. If the light source does not irradiate the deep blood vessel, the obtained third PPG signal is weak, in order to further improve the accuracy of blood pressure detection, the third PPG signal with the intensity smaller than the first threshold value according to the ranking sequence of the intensity sorted from large to small can be reserved, namely the third PPG signal with the intensity larger is reserved, and therefore a more accurate blood pressure value can be obtained through the screened third PPG signal with the intensity larger (namely the fourth PPG signal). The third PPG signals with the arrangement sequence being larger than the first threshold value are discarded, so that the measurement of the blood pressure is not influenced, and a more accurate blood pressure value can be obtained. Reference may be made in particular to the examples listed in the foregoing, which are not described in detail here.

S504 further includes:

s5043: and acquiring the compression pressure of the fourth PPG signal at the moment when the peak-to-peak value of the fourth PPG signal is maximum according to the fourth PPG signal and the compression pressure.

And obtaining the blood pressure of the user according to the compression pressure at the moment when the peak-to-peak value of the fourth PPG signal is maximum.

Referring to fig. 8, S504 may further include:

s5044: and sorting fourth PPG signals respectively acquired by a plurality of pixel units in the fingerprint detection device from large to small according to the pressing pressure to obtain a fourth PPG signal envelope, and reserving signals with the sequence number smaller than or equal to a second threshold value in the fourth PPG signal envelope, wherein the second threshold value is the ratio of the sequence number of the fourth PPG signals to the number of the fourth PPG signals, and the fourth PPG signals with the sequence number smaller than or equal to the second threshold value are fifth PPG signals.

Alternatively, the second threshold may be 30%, 25% or 20%. The larger the pressure corresponding to the fourth PPG signal envelope peak is, the more deep aorta signals acquired by the pixel unit are represented. Therefore, the accuracy of blood pressure detection can be further improved by further screening out the fourth PPG signal which is less than or equal to the second threshold value. Because the information carried by the fourth PPG signal with the arrangement sequence being positioned in front is closer to the aorta in the body, the fourth PPG signal with the arrangement sequence being larger than the second threshold value is discarded, the measurement of the blood pressure is not influenced, and a more accurate blood pressure value can be obtained. Reference may be made in particular to the examples listed in the foregoing, which are not described in detail here.

Furthermore, if the isolated pixel units with large position deviations, which may be signal interference, such as sympathetic nerve activity, are directly discarded, the fifth PPG signal acquired by the isolated pixel unit of the fingerprint detection device corresponding to the fourth PPG signal acquired by the pixel unit adjacent to the isolated pixel unit can be discarded or rejected.

S504 further includes:

s5035: discarding the fifth PPG signal correspondingly acquired by an isolated pixel unit in the fingerprint detection device, where the fourth PPG signal acquired by a pixel unit adjacent to the isolated pixel unit is discarded, and a fifth PPG signal remaining after discarding the fifth PPG signal correspondingly acquired by the isolated pixel unit is a sixth PPG signal.

Since the transverse arch artery is a blood vessel with a band-shaped distribution and has a certain width, the pixel units corresponding to the fifth PPG signal, i.e. the sixth PPG signal, which is retained at this step should be band-shaped. And performing blood pressure calculation by using the PPG signals obtained by the pixel units of the part to obtain the blood pressure which is closer to the blood pressure of the aorta in vivo.

S5036: and acquiring the blood pressure of the user according to the sixth PPG signal and the compression pressure.

Specifically, the mean arterial pressure of the user may be obtained according to a sixth PPG signal envelope formed by the sixth PPG signal, and then the blood pressure of the user is obtained according to the mean arterial pressure, specifically, the blood pressure value may be calculated according to a coefficient method or a double gaussian fitting method, and the method for calculating the blood pressure value is not limited in the embodiment of the present application as long as the blood pressure of the user can be calculated. Wherein, the mean arterial pressure may be a pressure corresponding to the sixth PPG signal envelope peak.

It should be understood that the processing unit or processor of the embodiments of the present application may be an integrated circuit chip having signal processing capabilities. In implementation, the steps of the above method embodiments may be performed by integrated logic circuits of hardware in a processor or instructions in the form of software. The Processor may be a general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic device, or discrete hardware components. The various methods, steps, and logic blocks disclosed in the embodiments of the present application may be implemented or performed. It is understood that the blood pressure detecting device of the embodiment of the present application may further include a storage unit or a memory, and the memory may be a volatile memory or a nonvolatile memory, or may include both a volatile memory and a nonvolatile memory.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.

The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application may be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the methods described in the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A fingerprint detection device is suitable for an electronic device with a display screen, the fingerprint detection device is arranged below the display screen and used for detecting blood pressure, the electronic device comprises a light source, the light source comprises a first light source and a second light source, the fingerprint detection device is used for receiving a first light signal which is reflected by a finger of a user and passes through the display screen at a first moment, and the first light signal is a light signal with a first wavelength and emitted by the first light source;

2. The fingerprint detection device of claim 1, wherein the display screen is an OLED display screen, and the light source is a light emitting pixel of the OLED display screen.

3. The fingerprint detection device of claim 2, wherein the first light source is a red light emitting pixel and the second light source is a blue light emitting pixel or a green light emitting pixel.

4. Fingerprint detection apparatus according to claim 1, wherein the fingerprint detection apparatus is configured to obtain the third PPG signal by differencing the first PPG signal and the second PPG signal; or

The fingerprint detection device is configured to obtain the third PPG signal by normalizing the first PPG signal and the second PPG signal.

5. The fingerprint detection apparatus according to claim 1, wherein the fingerprint detection apparatus is configured to obtain the blood pressure of the user according to the third PPG signal and the pressure of the user's finger pressing on the display screen.

6. The fingerprint detection apparatus according to claim 5, wherein the fingerprint detection apparatus is configured to obtain the pressing pressure of the user's finger on the display screen according to the pressing area of the user's finger on the display screen and the pressing pressure of the user's finger on the display screen, wherein the pressing area of the user's finger on the display screen is obtained by the fingerprint detection apparatus or the display screen.

7. The fingerprint detection device according to claim 6, wherein the fingerprint detection device is configured to form a fingerprint image after receiving an optical signal reflected by a surface of a user's finger, the fingerprint image is configured to obtain a pressing area of the user's finger pressing on the display screen, and the optical signal is emitted by the light source.

8. The fingerprint detection apparatus according to claim 1 or 5, wherein the fingerprint detection apparatus is configured to sort, according to the intensity of the third PPG signal, third PPG signals respectively acquired by a plurality of pixel units in the fingerprint detection apparatus from large to small, and retain signals with a ranking number smaller than or equal to a first threshold in the sorted third PPG signals, where the first threshold is a ratio of the ranking number of the third PPG signals to the number of the third PPG signals, and the third PPG signals with the ranking number smaller than or equal to the first threshold are fourth PPG signals.

9. The fingerprint detection apparatus of claim 8, wherein the first threshold is 30%, 25%, or 20%.

10. Fingerprint detection apparatus according to claim 8, wherein the fingerprint detection apparatus is configured to obtain the compression pressure at the time when the peak-to-peak value of the fourth PPG signal is maximum from the fourth PPG signal and the compression pressure.

11. The fingerprint detection device according to claim 8, wherein the fingerprint detection device is configured to sort, according to the compression pressure, the fourth PPG signals respectively acquired by the plurality of pixel units in the fingerprint detection device from large to small to obtain a fourth PPG signal envelope, and retain a signal with a sequence number smaller than or equal to a second threshold in the fourth PPG signal envelope, where the second threshold is a ratio of the sequence number of the fourth PPG signal to the number of the fourth PPG signals, and the fourth PPG signal with the sequence number smaller than or equal to the second threshold is a fifth PPG signal.

12. The fingerprint detection apparatus of claim 11, wherein the second threshold is 30%, 25%, or 20%.

13. The fingerprint detection apparatus according to claim 11, wherein the fingerprint detection apparatus is further configured to discard the fifth PPG signal obtained by a pixel unit corresponding to an isolated pixel in the fingerprint detection apparatus, and the fourth PPG signal obtained by a pixel unit adjacent to the isolated pixel is discarded, wherein after the fifth PPG signal obtained by the pixel unit corresponding to the isolated pixel is discarded, the remaining fifth PPG signal is a sixth PPG signal, and the sixth PPG signal is used to obtain the blood pressure of the user.

14. The fingerprint detection apparatus according to claim 7, wherein the fingerprint detection apparatus is configured to determine whether the pressing area of the finger of the user includes a fingerprint center according to the fingerprint image, and if it is determined that the pressing area of the finger of the user does not include the fingerprint center, terminate the blood pressure detection.

15. The fingerprint detection apparatus of claim 1, wherein the fingerprint detection apparatus comprises a processor configured to perform the blood pressure detection.

16. An electronic device, comprising:

a display screen, a fingerprint sensing device as defined in any one of claims 1 to 15, wherein said fingerprint sensing device is arranged below said display screen for performing blood pressure sensing.

17. The electronic device of claim 16, further comprising a pressure sensor disposed below the display screen adjacent to the fingerprint recognition device.

18. The electronic device of claim 16, further comprising a light source, wherein the display screen is an OLED display screen, and wherein the light source is a light-emitting pixel of the OLED display screen.

19. A blood pressure detection method is characterized by comprising the following steps:

at a first moment, a fingerprint detection device receives a first optical signal which is reflected by a finger of a user and passes through a display screen, wherein the first optical signal is an optical signal with a first wavelength emitted by a first light source and is used for acquiring a first PPG signal;

at a second moment, the fingerprint detection device receives a second optical signal which is reflected by the finger of the user and passes through the display screen, wherein the second optical signal is an optical signal with a second wavelength emitted by the second light source and is used for acquiring a second PPG signal;

obtaining a third PPG signal according to the first PPG signal and the second PPG signal, wherein the third PPG signal is used for obtaining the blood pressure of the user, and the first wavelength is different from the second wavelength.

20. The method of claim 19, wherein the display screen is an OLED display screen, and the first light source and the second light source are light emitting pixels of the OLED display screen.

21. The method of claim 20, wherein the first light source is a red light-emitting pixel and the second light source is a blue light-emitting pixel or a green light-emitting pixel.

22. A method of blood pressure detection as claimed in claim 19 wherein obtaining a third PPG signal from the "first and second PPG signals" comprises:

obtaining a third PPG signal by subtracting the first PPG signal and the second PPG signal; or

Normalizing the first PPG signal and the second PPG signal to obtain the third PPG signal.

23. The blood pressure detection method according to claim 20, further comprising:

and acquiring the pressing pressure of the finger of the user pressing the display screen, and acquiring the blood pressure of the user according to the third PPG signal and the pressing pressure.

24. The method for detecting blood pressure according to claim 23, wherein said obtaining the pressing pressure of the user's finger pressing the display screen comprises:

and acquiring the pressing pressure of the user finger on the display screen according to the pressing area of the user finger on the display screen and the pressing pressure of the user finger on the display screen, wherein the pressing area of the user finger on the display screen is acquired through the fingerprint detection device or the display screen.

25. The blood pressure detecting method according to claim 24, wherein the "acquiring of the pressing area of the user's finger on the display screen by the fingerprint detecting device or the display screen" includes:

the fingerprint detection device forms a fingerprint image according to the received optical signal reflected by the surface of the user finger, and the fingerprint image is used for acquiring the pressing area of the user finger on the display screen.

26. A method for blood pressure detection according to claim 20 or 23, wherein the "obtaining the blood pressure of the user from the third PPG signal and the compression pressure. "comprises:

sorting third PPG signals respectively acquired by a plurality of pixel units in the fingerprint detection device from large to small according to the intensity of the third PPG signals, and reserving signals with the sequence number smaller than or equal to a first threshold value in the sorted third PPG signals, wherein the first threshold value is the ratio of the sequence number of the third PPG signals to the number of the third PPG signals, and the third PPG signals with the sequence number smaller than or equal to the first threshold value are fourth PPG signals.

27. A method for detecting blood pressure according to claim 26, wherein the first threshold value is 30%, 25% or 20%.

28. A method for blood pressure detection according to claim 26 wherein said obtaining a compression pressure of a user's finger pressing said display screen obtains a user's blood pressure from said third PPG signal and said compression pressure. "further includes:

and acquiring the compression pressure of the fourth PPG signal at the moment when the peak-to-peak value of the fourth PPG signal is maximum according to the fourth PPG signal and the compression pressure.

29. A method for blood pressure detection according to claim 26 wherein said obtaining a compression pressure of a user's finger pressing said display screen obtains a user's blood pressure from said third PPG signal and said compression pressure. "further includes:

and sorting the fourth PPG signals respectively acquired by a plurality of pixel units in the fingerprint detection device from large to small according to the pressing pressure to obtain a fourth PPG signal envelope, and reserving signals with the sequence number smaller than or equal to a second threshold value in the fourth PPG signal envelope, wherein the second threshold value is the ratio of the sequence number of the fourth PPG signals to the number of the fourth PPG signals, and the fourth PPG signals with the sequence number smaller than or equal to the second threshold value are fifth PPG signals.

30. A method for detecting blood pressure according to claim 26, wherein the second threshold value is 30%, 25% or 20%.

31. A method as claimed in claim 29, wherein the step of obtaining the pressure at which the user's finger presses the display screen obtains the user's blood pressure from the third PPG signal and the pressure. "further includes:

discarding the fifth PPG signal correspondingly acquired by an isolated pixel unit in the fingerprint detection device, wherein the fourth PPG signal correspondingly acquired by an adjacent pixel unit is discarded, and the remaining fifth PPG signal is a sixth PPG signal after the fifth PPG signal correspondingly acquired by the isolated pixel unit is discarded;

and acquiring the blood pressure of the user according to the sixth PPG signal and the compression pressure.

32. A method as claimed in claim 31, wherein the step of obtaining the pressure at which the user's finger presses the display screen obtains the user's blood pressure from the third PPG signal and the pressure. "further includes:

and acquiring the mean arterial pressure of the user according to a sixth PPG signal envelope formed by the sixth PPG signal, and acquiring the blood pressure of the user according to the mean arterial pressure.

33. The blood pressure detecting method according to claim 25, wherein the step of acquiring the area of the display screen pressed by the finger of the user through the fingerprint detecting device or the display screen further comprises:

34. The method for detecting blood pressure according to claim 33, wherein determining whether the pressed region of the finger of the user includes a fingerprint center based on the fingerprint image comprises:

judging whether a pressing area of a finger of a user contains a fingerprint center by adopting a tangent method, wherein the tangent method is to find two non-parallel fingerprint lines on the fingerprint image at will and respectively tangent the two fingerprint lines;

if the focal points of the two normal lines are positioned in the fingerprint image, the pressing area of the finger of the user comprises the fingerprint center;

and if the focal points of the two normal lines are positioned outside the fingerprint image, the pressing area of the finger of the user does not contain the fingerprint center.

35. The method according to claim 34, wherein if the area pressed by the finger of the user includes a center of the fingerprint, the light-emitting pixels in a rectangular range having a width R and a length S around an orthogonal projection of the center of the fingerprint on the display screen are lit, wherein the width direction is a direction along the length of the finger, the length direction is a direction of the width of the finger, and R is equal to or less than 3 mm.