An electrocardio detection system, living body fingerprint identification device, method and intelligent door lock

Abstract

The application discloses an electrocardio detection system, a living body fingerprint identification device and method and an intelligent door lock. The electrocardio detection system comprises an electrocardio collection module, which is used for collecting electrocardio signals of a test object; a first amplification module, which is used for receiving the collected electrocardio signals, amplifying the electrocardio signals and outputting a first amplification signal; a negative feedback module, which is connected in parallel with the first amplification module, and is used for filtering impurity signals in the first amplification signal and stably outputting the first amplification signal; a second amplification module, which receives the first amplification signal, amplifies the first amplification signal and outputs a second amplification signal; a low-pass filter module, which receives the second amplification signal, processes the second amplification signal and outputs; and an analog-digital conversion module, which receives the processed signal, converts the processed signal into a digital signal and outputs electrocardio information of the test object. The electrocardio detection system adopts two-stage step-by-step amplification of electrocardio signals, and performs negative feedback processing on the first amplification signal, so that more accurate electrocardio signals can be obtained.

Description

Technical Field

[0001] The present invention relates to the field of fingerprint recognition technology, and in particular to an electrocardiogram detection system, a live fingerprint recognition device and method, and an intelligent door lock. Background Art

[0002] With the advancement of information and electronics, electronic devices (tablets, mobile phones, smart door locks, etc.) have become inseparable from people's lives, and the security issues surrounding these devices have also attracted considerable attention. Currently, fingerprints are commonly used as information features to unlock devices, i.e., fingerprint recognition systems are used for device security management. However, fingerprint unlocking has a significant vulnerability: by extracting residual fingerprints, then using materials such as gelatin, silicone, or rubber to create a fingerprint cover that matches the extracted fingerprint pattern, and then wearing the fingerprint cover on a finger or a fake finger, the fingerprint recognition system can be deceived. This poses a significant security risk to fingerprint recognition systems.

[0003] Chinese patent publication CN107194382A discloses a live fingerprint recognition device that combines an electrocardiogram (ECG) detection module (photoelectric heart rate detection module) with a phased array biometric recognition module to reduce the risk of the fingerprint recognition device being deceived by counterfeit fingerprints and improve the security of the fingerprint recognition device. However, the ECG detection module of the device has low sensitivity and accuracy, which is not conducive to liveness recognition. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem that the detection sensitivity and accuracy of the electrocardiography detection module in the prior art are not high, which is not conducive to live body recognition.

[0005] To solve the above technical problems, an embodiment of the present invention discloses an ECG detection system, comprising: an ECG acquisition module, for acquiring the ECG signal of a subject; a first amplification module, for receiving the ECG signal acquired by the ECG acquisition module, amplifying the ECG signal and outputting a first-stage amplified signal; a negative feedback module, connected in parallel with the first amplification module, for filtering out impurity signals in the first-stage amplified signal and maintaining a stable output of the first-stage amplified signal; a second amplification module, for receiving the first-stage amplified signal, amplifying the first-stage amplified signal and outputting a second-stage amplified signal; a low-pass filtering module, for receiving the second-stage amplified signal and outputting it after processing; and an analog-to-digital conversion module, for receiving the processed signal output by the low-pass filtering module and converting the processed signal into a digital signal and then outputting the ECG information of the subject.

[0006] Utilizing the above technical solution, the ECG signal collected by the ECG acquisition module is amplified in two stages, and the first-stage amplified signal output by the first amplification module is subjected to negative feedback processing. That is, the negative feedback module is used to filter out impurity signals in the first-stage amplified signal to prevent the ECG signal from being distorted after the first-stage amplification. The negative feedback module can also ensure the stable output of the first-stage amplified signal. The first-stage amplified signal is then amplified in the second stage, and a low-pass filtering module is provided to remove interference from high-frequency electromagnetic waves and power frequency signals in the second-stage amplified signal. The signal processed by the low-pass filtering module is then converted into a digital signal for output by the analog-to-digital conversion module, thereby obtaining a more accurate ECG signal.

[0007] Optionally, in the ECG detection system provided in an embodiment of the present invention, the negative feedback module includes: a third resistor, a fourth resistor, a ninth resistor, a first capacitor and a third operational amplifier; wherein, the positive phase input terminal of the third operational amplifier is connected to the second amplification module, the negative phase input terminal of the third operational amplifier is respectively connected to the second end of the ninth resistor and the second end of the first capacitor, and the output terminal of the third operational amplifier is respectively connected to the first end of the first capacitor and the first amplification module; the first end of the third resistor is respectively connected to the first amplification module and the ECG acquisition module, the second end of the third resistor is respectively connected to the second end of the fourth resistor and the positive phase input terminal of the third operational amplifier; the first end of the fourth resistor is respectively connected to the first amplification module and the ECG acquisition module; the first end of the ninth resistor is respectively connected to the first amplification module and the second amplification module.

[0008] Optionally, in the electrocardiogram detection system provided in an embodiment of the present invention, the negative feedback module also includes: a seventh resistor, an eighth resistor and a fourth capacitor; wherein the first end of the seventh resistor is connected to the power supply end, the second end of the seventh resistor, the first end of the eighth resistor and the first end of the fourth capacitor are all connected to the non-inverting input end of the third operational amplifier; the second end of the eighth resistor and the second end of the fourth capacitor are both connected to the ground end.

[0009] Optionally, in the electrocardiogram detection system provided in an embodiment of the present invention, the first amplification module is an operational amplifier of model AD627.

[0010] Optionally, the electrocardiogram detection system provided in the embodiment of the present invention further includes: a digital filtering module, and the digital filtering module is connected to the analog-to-digital conversion module.

[0011] Optionally, in the electrocardio detection system provided by the embodiment of the present application, the second amplification module specifically comprises: a fifth resistor, a sixth resistor, a second operational amplifier and a second capacitor; wherein the positive phase input end of the second operational amplifier is connected with the negative feedback module, the negative phase input end of the second operational amplifier is connected with the second end of the fifth resistor, the first end of the sixth resistor and the first end of the second capacitor respectively, the output end of the second operational amplifier is connected with the low-pass filter module, and is used for outputting a second-level amplified signal; the first end of the fifth resistor is connected with the first amplification module, and is used for receiving a first-level amplified signal; and the second end of the sixth resistor is connected with the second end of the second capacitor and the output end of the second operational amplifier respectively.

[0012] Optionally, in the electrocardio detection system provided by the embodiment of the present application, the low-pass filter module specifically comprises: a tenth resistor and a third capacitor, wherein the first end of the tenth resistor is connected with the second amplification module, and is used for receiving a second-level amplified signal; the second end of the tenth resistor and the first end of the third capacitor are both connected with the analog-digital conversion module, and are used for outputting a processed signal; and the second end of the third capacitor is connected with the ground end.

[0013] Optionally, in the electrocardio detection system provided by the embodiment of the present application, the amplification multiple of the second amplification module is 25-50 times of the amplification multiple of the first amplification module.

[0014] Optionally, in the electrocardio detection system provided by the embodiment of the present application, further comprising: a first resistor and a second resistor; the first end of the first resistor is connected with the electrocardio acquisition module, and the second end of the first resistor is connected with the first amplification module; and the first end of the second resistor is connected with the electrocardio acquisition module, and the second end of the second resistor is connected with the first amplification module.

[0015] Correspondingly, the embodiment of the present application further provides a living body fingerprint identification device, comprising: the electrocardio detection system provided by any one of the above-mentioned embodiments of the present application, which is used for detecting the electrocardio information of a subject; a living body judgment module, which is used for comparing the detected electrocardio information of the subject with first preset information, so as to judge whether the subject is a living body; if the electrocardio information of the subject is within the first preset information range, then the subject is a living body; a fingerprint detection module, which is used for detecting the fingerprint information of the subject; and a fingerprint verification module, which is used for comparing the detected fingerprint information of the subject with registered fingerprint information, and the registered fingerprint information is registered in the living body fingerprint identification device by a user in advance; wherein, if the subject is a living body and the fingerprint information of the subject is consistent with the registered fingerprint information, then the verification is passed.

[0016] Optionally, the live fingerprint recognition device provided in an embodiment of the present invention further includes: a health detection module, which is used to compare the electrocardiogram information of the subject with the second preset information after the liveness judgment module determines whether the subject is alive, when the subject is alive, to determine the health status of the subject; wherein, if the electrocardiogram information is not within the second preset information range, the subject is in an unhealthy state; and the first preset information range includes the second preset information range.

[0017] Optionally, the live fingerprint recognition device provided in the embodiment of the present invention further includes: an alarm module, configured to issue an alarm when the subject is in an unhealthy state after the health detection module determines the health state of the subject.

[0018] Optionally, the live fingerprint recognition device provided in an embodiment of the present invention further includes: an activation module, which is used to activate the fingerprint detection module to detect the fingerprint information of the subject when the subject is alive, after the live judgment module determines whether the subject is alive and before the fingerprint detection module detects the fingerprint information of the subject.

[0019] Optionally, the live fingerprint recognition device provided in the embodiment of the present invention further includes: a contact detection module, which is used to detect the touch of the subject before the ECG detection system detects the ECG information of the subject, and activate the ECG detection system when the touch of the subject is detected.

[0020] Optionally, the live fingerprint recognition device provided in the embodiment of the present invention further includes: a storage module, configured to store registered fingerprint information and / or first preset information before the electrocardiogram detection system detects the electrocardiogram information of the subject.

[0021] Correspondingly, an embodiment of the present invention further provides a smart door lock, comprising the live fingerprint recognition device provided by any of the above embodiments of the present invention.

[0022] Correspondingly, an embodiment of the present invention also provides a live fingerprint recognition method, including: an electrocardiogram detection step, detecting the electrocardiogram information of the subject; a liveness judgment step, comparing the detected electrocardiogram information of the subject with first preset information to determine whether the subject is alive; if the electrocardiogram information of the subject is within the range of the first preset information, the subject is alive; a fingerprint detection step, detecting the fingerprint information of the subject; a fingerprint verification step, comparing the detected fingerprint information of the subject with registered fingerprint information, and the registered fingerprint information is pre-registered by the user; wherein, if the subject is alive and the fingerprint information of the subject is consistent with the registered fingerprint information, the verification is passed.

[0023] Optionally, in the live fingerprint recognition method provided in an embodiment of the present invention, after the liveness judgment step, it also includes: a health detection step, when the subject is alive, the electrocardiogram information of the subject is compared with the second preset information to determine the health status of the subject; wherein, if the electrocardiogram information is within the second preset information range, the subject is in an unhealthy state; the first preset information range contains the second preset information range.

[0024] Optionally, in the live fingerprint recognition method provided in the embodiment of the present invention, after the health detection step, it further includes: an alarm step of issuing an alarm when the subject is in an unhealthy state.

[0025] Optionally, in the live fingerprint recognition method provided by the embodiment of the present invention, after the liveness determination step and before the fingerprint detection step, it further includes: an activation step, when the subject is alive, executing the fingerprint detection step.

[0026] Optionally, in the live fingerprint recognition method provided in the embodiment of the present invention, before the electrocardiogram detection step, the method further includes: a contact detection step of detecting the touch of the subject, and when the touch of the subject is detected, the electrocardiogram detection step is executed.

[0027] Optionally, in the live fingerprint recognition method provided by the embodiment of the present invention, before the electrocardiogram detection step, the method further includes: a storage step for storing registered fingerprint information and / or first preset information.

[0028] Compared with the prior art, the present invention has the following technical effects:

[0029] The ECG signal collected by the ECG acquisition module is amplified in two stages, and negative feedback processing is performed on the first-stage amplification signal output by the first-stage amplification module. That is, the negative feedback module is used to filter out impurity signals composed of static signals caused by human body surface friction, weak electromagnetic wave signals in the air, etc. in the first-stage amplification signal to prevent the ECG signal from being distorted after the first-stage amplification. Then, the second-stage amplification is performed, and a low-pass filtering module is set to remove interference from high-frequency electromagnetic waves and power frequency signals in the second-stage amplification signal. Then, the signal processed by the low-pass filtering module is converted into a digital signal output by the analog-to-digital conversion module to obtain a more accurate ECG signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the structure of an electrocardiogram detection system provided by a specific embodiment of the present invention. Figure 1 ;

[0031] Figure 2 This is a schematic diagram of the structure of an electrocardiogram detection system provided by a specific embodiment of the present invention. Figure 2 ;

[0032] Figure 3 It is a schematic diagram of the specific structure of an electrocardiogram detection system provided by a specific embodiment of the present invention;

[0033] Figure 4 This is a schematic diagram of the structure of a live fingerprint recognition device provided by a specific embodiment of the present invention. Figure 1 ;

[0034] Figure 5 This is a schematic diagram of the structure of a live fingerprint recognition device provided by a specific embodiment of the present invention. Figure 2 ;

[0035] Figure 6 The figure is a flow chart of a live fingerprint recognition method provided by a specific embodiment of the present invention. DETAILED DESCRIPTION

[0036] The following is an explanation of the embodiments of the present invention by specific specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to this embodiment. On the contrary, the purpose of introducing the invention in conjunction with the embodiment is to cover other options or modifications that may be extended based on the claims of the present invention. In order to provide a deep understanding of the present invention, the following description will contain many specific details. The present invention can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present invention, some specific details will be omitted in the description. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0037] The terms used in this disclosure are for the purpose of describing specific embodiments only and are not intended to limit the disclosure. As used in this disclosure and the appended claims, the singular forms "a," "an," "above," and "the" are intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0038] It should be noted that in this specification, similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0039] In the description of this embodiment, it should be noted that the terms "first," "second," etc., are used only to distinguish descriptions and should not be understood to indicate or imply relative importance. Depending on the context, the word "if" as used herein can be interpreted as "at the time of," "when," or "in response to a determination."

[0040] In order to make the objects, technical solutions and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the drawings.

[0041] With reference to Figure 1 According to the specific embodiment of the present application, an electrocardio detection system 100 comprises, in sequence, an electrocardio acquisition module 1, a first amplification module 2, a second amplification module 3, a low-pass filter module 4, and an analog-digital conversion module 5, and the electrocardio detection system 100 further comprises a negative feedback module 6 connected in parallel with the first amplification module 2, i.e. the negative feedback module 6 is connected with the electrocardio acquisition module 1, the first amplification module 2 and the second amplification module 3 respectively; wherein the electrocardio acquisition module 1 is used to acquire the electrocardio signal of a subject, then the first amplification module 2 receives the electrocardio signal acquired by the electrocardio acquisition module 1, amplifies the electrocardio signal and outputs a first-level amplified signal. The negative feedback module 6 is used to remove the impurity signal in the first-level amplified signal and maintain the stable output of the first-level amplified signal. The second amplification module 3 receives the first-level amplified signal, amplifies the first-level amplified signal and outputs a second-level amplified signal. The low-pass filter module 4 receives the second-level amplified signal and processes it to output a processed signal. Finally, the analog-digital conversion module 5 receives the processed signal output by the low-pass filter module 4, converts the processed signal into a digital signal and outputs the electrocardio information of the subject. Here, the electrocardio information can be an electrocardio waveform graph.

[0042] Because the electrocardio signal acquired by the electrocardio acquisition module 1 contains not only the electrocardio signal of the human body, but also the impurity signal composed of the static signal caused by the friction of the human body surface, the weak electromagnetic wave in the air and the like, the high-frequency electromagnetic wave and the power frequency signal and the like noise signal, if only one amplification is used to amplify the signal acquired by the electrocardio acquisition module 1 by several thousand times, the electrocardio signal will be covered by the noise signal, resulting in the distortion of the electrocardio signal, so that the required electrocardio signal of the human body cannot be effectively obtained.

[0043] The electrocardio detection system 100 amplifies the signal by two levels, and performs negative feedback processing on the first-level amplified signal output by the first amplification module, filters the impurity signal composed of the static signal caused by the friction of the human body surface, the weak electromagnetic wave signal in the air and the like in the first-level amplified signal through the negative feedback module 6, so as to prevent the electrocardio signal from being distorted after the first amplification, and then amplify the first-level amplified signal by two levels, and remove the high-frequency electromagnetic wave and the power frequency signal and the like in the second-level amplified signal through the low-pass filter module 4, so as to obtain a more accurate electrocardio signal of the human body.

[0044] With reference to Figure 3The ECG acquisition module 1 can include two ECG sensors, a first ECG sensor T1 and a second ECG sensor T2. Preferably, the ECG sensors T1 and T2 can be used to sense the ECG signals at the thumb and the palm of the same hand, respectively. Of course, the ECG sensors T1 and T2 can also be used to acquire ECG signals at other parts, which are not limited herein. Moreover, the acquired ECG signals do not necessarily have to be complete signals, but can only include some specific information, such as the peak and trough information in the ECG wave signal. The two ECG sensors can constitute a capacitor, and the two capacitors are capacitively coupled to the ECG potential of the body surface.

[0045] As shown in Figure 1 , the ECG signals acquired by the ECG acquisition module 1 are input to the first amplification module for amplification processing. Due to the characteristics of the ECG signals of the human body, such as small amplitude, low frequency, easy to be disturbed, unstable, strong randomness, etc., the design of the ECG amplification circuit is required to be very strict, and the selection of the amplifier is particularly important. When selecting an amplifier, several aspects such as gain, frequency response, input impedance, common-mode rejection ratio, noise, drift, etc. need to be considered comprehensively, such as selecting some differential amplifiers with high input impedance, low noise, low drift, high gain and high common-mode rejection ratio, to prevent output saturation, stabilize output, and reduce the transmission of common-mode interference.

[0046] As a preferred embodiment of the present application, the first operational amplification module can be an operational amplifier with a model number AD627 (hereinafter referred to as the first operational amplifier AR1). Referring to Figure 3 , the non-inverting input terminal of the first operational amplifier AR1 (i.e. the positive stage of AR1 in Figure 3 ) is connected to the first end of the fourth resistor R4 and the output terminal of the third operational amplifier AR3, respectively. The inverting input terminal of the first operational amplifier AR1 (i.e. the negative stage of AR1 in Figure 3 ) is connected to the first end of the third resistor R3, and the output terminal of the first operational amplifier is connected to the first end of the ninth resistor.

[0047] The reason why the operational amplifier with the model number AD627 is used as the first amplification module is that the precision of the amplification factor of AD627 is higher than that of the amplification circuit which needs to rely on resistance adjustment for multiple adjustment, and the circuit is simpler, so that the circuit layout of the ECG detection system 100 can be simplified, thereby making the structure of the ECG detection system 100 more compact and smaller in size. Moreover, the amplification factor of AD627 is 5 times, and the ECG signals acquired by the ECG acquisition module are amplified by 5 times by AD627, which is more conducive to the removal of impurity signals.

[0048] Referring to Figure 3As a preferred embodiment of the present invention, the negative feedback module 6 is connected to the ECG acquisition module 1, the first amplification module 2 and the second amplification module 3 respectively. The negative feedback module 6 may specifically include a third resistor R3, a fourth resistor R4, a ninth resistor R9, a first capacitor C1 and a third operational amplifier AR3. Among them, the positive input terminal of the third operational amplifier AR3 (i.e. Figure 3 The positive terminal of AR3 in the middle) is connected to the second amplifying module 3, and the negative input terminal of the third operational amplifier AR3 (ie Figure 3 The negative terminal of AR3 is respectively connected to the second end of the ninth resistor R9 and the second end of the first capacitor C1, and the output end of the third operational amplifier AR3 is respectively connected to the first end of the first capacitor C1 and the first amplifying module 2; the first end of the third resistor R3 is respectively connected to the first amplifying module 2 and the ECG acquisition module 1, and the second end of the third resistor R3 is respectively connected to the second end of the fourth resistor R4 and the non-inverting input end of the third operational amplifier AR3; the first end of the fourth resistor R4 is respectively connected to the first amplifying module 2 and the ECG acquisition module 1; and the first end of the ninth resistor R9 is respectively connected to the first amplifying module 2 and the second amplifying module 3.

[0049] Specifically, the ninth resistor R9 receives the first-stage amplified signal (hereinafter referred to as Vout1) output by the first operational amplifier AR1 and transmits the signal to the negative-phase input terminal of the third operational amplifier AR3. The third resistor R3 and the fourth resistor R4 transmit the DC component of the received input signal (hereinafter referred to as Vout2) to the positive-phase input terminal of the third operational amplifier AR3. At this time, the output terminal of the third operational amplifier AR3 outputs a signal Vout3 = (Vout1 - Vout2) * K1 (K1 is a coefficient whose value is related to the resistance values ​​of the third, fourth, and ninth resistors and the characteristics of the third operational amplifier). Finally, the third operational amplifier outputs the signal Vout3 to the positive-phase input terminal of the first operational amplifier AR1. Similarly, the first-stage amplified signal Vout1 output by the first operational amplifier AR1 is equal to the difference between the signal at its negative-phase input terminal and the signal at its positive-phase input terminal, multiplied by a certain proportionality coefficient. This proportionality coefficient is related to the characteristics of the first operational amplifier AR1.

[0050] As can be seen from the above, when the first-stage amplified signal Vout1 output by the first operational amplifier AR1 increases, the signal Vout3 also increases accordingly. Since Vout3 is transmitted to the non-inverting input terminal of AR3, the difference between the signal at the negative-inverting input terminal of the first operational amplifier AR1 and the signal at its non-inverting input terminal decreases accordingly. Ultimately, the first-stage amplified signal Vout1 output by the output terminal of the first operational amplifier decreases accordingly. That is, through the regulation of the negative feedback module, when the signal Vout1 at the output terminal of the first operational amplifier AR1 increases, the amplitude of Vout1 is automatically reduced. Conversely, when Vout1 decreases, the amplitude of Vout1 can be increased through the negative feedback module, so that Vout1 is always in a dynamic equilibrium state.

[0051] As a preferred embodiment of the present invention, the negative feedback module 6 may further include a seventh resistor R7, an eighth resistor R8, and a fourth capacitor C4. A first end of the seventh resistor R7 is connected to the power supply terminal VCC, a second end of the seventh resistor R7, a first end of the eighth resistor R8, and a first end of the fourth capacitor C4 are all connected to the non-inverting input terminal of the third operational amplifier AR3, and a second end of the eighth resistor R8 and a second end of the fourth capacitor C4 are both connected to the ground terminal.

[0052] Specifically, by adjusting the ratio of R7 / R8, the value of the signal Vout2 transmitted to the non-inverting input terminal of the third operational amplifier AR3 can be changed, thereby changing the variation amplitude of Vout1-Vout2, improving the variation sensitivity of the output signal Vout3 of the third operational amplifier AR3, and thus enabling the first-stage amplified signal Vout1 of the first operational amplifier AR1 to be always maintained at an amplification factor of approximately 5 times, thereby avoiding the situation where the output signal amplitude of Vout3 is too large in the absence of negative feedback due to the input of an interference signal at the input terminal of the third operational amplifier AR3, or even causing signal distortion. In the entire circuit network, the first capacitor C1 and the fourth capacitor C4 play the role of filtering and stabilizing the amplitude. Their primary purpose is to remove impurity signals from the ECG signal. These impurity signals primarily consist of static electricity generated by human body friction and weak electromagnetic waves in the air. The values ​​of the first capacitor C1 and the fourth capacitor C4 are primarily related to the contact area between the first ECG sensor T1 and the first ECG sensor T2. The larger the contact area between T1 and T2, the wider the frequency range of the signal they collect. In other words, the frequency range of the high- and low-frequency signals contained in the ECG signal also increases. Since C1 and C4 primarily remove low-frequency signals, the capacitance values ​​of the first capacitor C1 and the fourth capacitor C4 should also be set to a larger value. In other words, the capacitance values ​​of the first capacitor C1 and the fourth capacitor C4 are positively correlated with the contact area between the ECG sensors T1 and T4.

[0053] As a preferred embodiment of the present invention, refer to Figure 3The second amplifying module 3 specifically includes: a fifth resistor R5, a sixth resistor R6, a second operational amplifier AR2 and a second capacitor C2; wherein the non-inverting input terminal of the second operational amplifier AR2 (ie Figure 3 The positive terminal of AR2 in the middle) is connected to the negative feedback module 6, and the negative input terminal of the second operational amplifier AR2 (ie Figure 3 The negative terminal of AR2 is connected to the second end of the fifth resistor R5, the first end of the sixth resistor R6, and the first end of the second capacitor C2. The output end of the second operational amplifier AR2 is connected to the low-pass filter module 4 for outputting the secondary amplified signal. The first end of the fifth resistor R5 is connected to the first amplification module 2 for receiving the primary amplified signal. The second end of the sixth resistor R6 is connected to the second end of the second capacitor C2 and the output end of the second operational amplifier AR2.

[0054] Specifically, the second operational amplifier AR2, the fifth resistor R5, the sixth resistor R6, and the second capacitor C2 form a two-stage amplifier circuit, the amplification factor of which is determined by R6 / R5. As a preferred embodiment of the present invention, the amplification factor of the second amplifier module 3 is 25 to 50 times that of the first amplifier module 1. Preferably, the product of the amplification factors of the first amplifier module and the second amplifier module is between 600 and 1300. In a specific implementation, the amplification factor of the first amplifier module 2 can be set to 5 times, while the amplification factor of the second amplifier module 3 can be set to 200 times. Therefore, after the first and second amplification steps, the subject's ECG signal can be amplified up to 1000 times. Generally, human ECG signals are very weak, only a few millivolts. Fluctuations within the millivolt range are not easily captured by analog-to-digital converters, resulting in signal distortion. However, by amplifying the weak ECG signal by 1000 times, raising it to a few volts, it is easier to process by the subsequent analog-to-digital converter and subsequent data processing.

[0055] As a preferred embodiment of the present invention, the low-pass filter module 4 in the electrocardiogram detection system 100 can specifically include a tenth resistor R10 and a third capacitor C3, wherein the first end of the tenth resistor R10 is connected to the second amplification module 3 for receiving the secondary amplified signal, the second end of the tenth resistor R10 and the first end of the third capacitor C3 are both connected to the analog-to-digital conversion module 5 for outputting the processed signal; the second end of the third capacitor C3 is connected to the ground end.

[0056] Specifically, the ECG detection system 100 includes a low-pass filter module 4, or an RC filter, with a cutoff frequency of 50 Hz. This filter only allows signals with frequencies no higher than 50 Hz to pass through. This filter is designed to eliminate the effects of noise signals such as high-frequency electromagnetic waves and power-frequency signals, thereby making the output voltage signal purer. With the increasing integration of electronic products into everyday life, the operation of radio broadcasts, television transmitters, communications equipment, radar, and other equipment in various frequency bands has significantly increased the amount of electromagnetic waves in the air. This high-frequency electromagnetic interference can also be introduced through the wires connecting the measurement system to the human body, potentially causing unstable measurement results and, in severe cases, rendering the measurement system inoperable. This has led to increasingly severe electromagnetic interference in various situations. Therefore, during the ECG signal acquisition process, not only is there interference from the 50 Hz power-frequency interference and low-frequency and DC components, but also from high-frequency harmonics exceeding the high-frequency portion of the normal ECG signal, such as those exceeding 100 Hz. Furthermore, the electronic equipment used for signal processing itself generates instrument noise, which generally has high-frequency characteristics. Therefore, it is necessary to utilize an RC filter for low-pass filtering.

[0057] refer to Figure 2 As a preferred embodiment of the present invention, the electrocardiogram detection system 100 may further include a digital filtering module 7 , which is connected to the analog-to-digital conversion module 5 .

[0058] Specifically, after the low-pass filter module 4 filters out interference signals with frequencies higher than 50 Hz, the signal is sent to the analog-to-digital conversion module 5 for data acquisition. Since the front-end electronic equipment in the electrocardiogram detection system 100 (such as the electronic components contained in each module such as the first amplification module, the second amplification module, and the analog-to-digital conversion module) may generate instrument noise during the signal acquisition and processing process, a digital filter module 7 is set here to eliminate instrument noise interference.

[0059] Preferably, the analog-to-digital conversion module 5 can be an analog-to-digital converter (ADC), which can convert a continuous analog signal into a discrete digital signal. The digital filtering module 7 can be a digital filter. The digital filter can calculate the signal according to the program to achieve the purpose of filtering. That is, by programming the memory of the digital filter, various filtering functions can be realized. For the digital filter, adding functions is to add programs without adding components and is not affected by component errors; the processing of low-frequency signals does not require increasing the size of the chip. Therefore, the digital filtering method can get rid of the problem of analog filters being limited by components, and has the advantages of high precision, high reliability, programmable change of characteristics or multiplexing, and easy integration.

[0060] As a preferred embodiment of the present application, the electrocardio detection system 100 can further comprise a first resistor R1 and a second resistor R2, wherein a first end of the first resistor R1 is connected with the electrocardio collection module 1, and a second end of the first resistor R1 is connected with the first amplification module 2; a first end of the second resistor R2 is connected with the electrocardio collection module 1, and a second end of the second resistor R2 is connected with the first amplification module 2.

[0061] Specifically, referring to Figure 3 When the first amplification module 2 is a first operational amplifier AR1, and the electrocardio collection module 1 is two electrocardio sensors T1, T2, one end of the first resistor R1 is connected with the first electrocardio sensor T1, and the second end of the first resistor R1 is connected with the negative phase input end of the first operational amplifier AR1; while one end of the second resistor R2 is connected with the second electrocardio sensor T2, and the second end of the second resistor R2 is connected with the positive phase input end of the first operational amplifier AR1. The first resistor and the second resistor can be used to reduce the influence of the electrostatic signal of the subject on the electrocardio signal.

[0062] For example, the specific working process of the circuit is as follows: Figure 3

[0063] The first electrocardio sensor T1 and the second electrocardio sensor T2 respectively collect the electrocardio signals at the thumb and the palm of the human hand, and then the electrocardio signals are respectively transmitted to the negative phase input end and the positive phase input end of the first operational amplifier AR1 after removing the electrostatic signal through the first resistor R1 and the second resistor R2, and the first operational amplifier AR1 amplifies the signals to output a first-level amplified signal. At the same time, since the first operational amplifier AR1 is connected in parallel with a negative feedback network, a ninth resistor receives the first-level amplified signal and transmits it to the negative phase input end of a third operational amplifier AR3, and by adjusting the ratio of the seventh resistor R7 and the eighth resistor R8, the third resistor R3 and the fourth resistor R4 transmit the signal to the positive phase input end of the third operational amplifier AR3, which is then processed by the third operational amplifier AR3 and fed back to the positive phase input end of the first operational amplifier AR1, thereby ensuring that the first-level amplified signal of the first operational amplifier AR1 can be stably output. At the same time, the fifth resistor R5 receives the first-level amplified signal and transmits it to the negative phase input end of the second operational amplifier AR2, while the positive phase input end of the second operational amplifier AR2 receives the direct current component in the electrocardio signal collected by the third resistor R3 and the fourth resistor R4, and the first-level amplified signal is amplified to a second-level amplified signal by the amplification of the second operational amplifier AR2, and then output to an RC filter composed of a tenth resistor R10 and a third capacitor C3 to remove impurity signals with a frequency higher than 50Hz, and then transmitted to an analog-to-digital converter ADC to convert the analog signal to a digital signal, and output the electrocardio waveform graph after removing the instrument noise signal by a digital filter.​

[0064] The electrocardiogram detection system provided by an embodiment of the present invention performs two-stage amplification and negative feedback processing on the first-stage amplified signal output by the first-stage amplification module. That is, the negative feedback module filters out impurity signals composed of static signals caused by friction on the human body surface and weak electromagnetic wave signals in the air in the first-stage amplified signal to prevent the electrocardiogram signal from being distorted after the first-stage amplification. Then, the second-stage amplification is performed, and the interference of signals such as high-frequency electromagnetic waves and power frequency signals is removed by a low-pass filtering module. Then, the signal processed by the low-pass filtering module is converted into a digital signal by an analog-to-digital conversion module for output, thereby obtaining a relatively accurate electrocardiogram signal.

[0065] The above is only an example to illustrate the specific structure of each module in the electrocardiogram detection system provided by the embodiment of the present invention. In specific implementation, the specific structure of the above modules is not limited to the above structure provided by the embodiment of the present invention, and can also be other structures known to those skilled in the art, which is again not limited.

[0066] Accordingly, the specific embodiment of the present invention also provides a live fingerprint recognition device, such as Figure 4 As shown, it includes: the ECG detection system 100 provided in the above specific embodiment, the liveness judgment module 200, the fingerprint detection module 300 and the fingerprint verification module 400; wherein, the ECG detection system 100 is used to detect the ECG information of the subject; the liveness judgment module 200 is used to compare the detected ECG information of the subject with the first preset information to determine whether the subject is alive; if the ECG information of the subject is within the range of the first preset information, the subject is alive.

[0067] As mentioned above, when the ECG information is an ECG waveform pattern, the first preset information should also be a set of ECG waveform patterns of the human body. The ECG waveform pattern of the subject can be fitted and compared with each pattern in the set of ECG waveform patterns in the first preset information through a processor. If they are consistent, the subject is considered alive. However, this method is cumbersome and time-consuming. As mentioned above, the ECG signal collected by the ECG detection system 100 provided in the embodiment of the present invention does not necessarily have to be a complete signal, but can only contain certain specific information, such as peaks, troughs, and frequency information in the ECG wave signal. Accordingly, the first preset information range mentioned here does not necessarily include all characteristic information of the human ECG, but can only include the range of certain parameters related to the human ECG information. Preferably, the first preset information includes information on parameters such as peaks, troughs, and frequency in the ECG information. It should be noted that the first preset information is not limited to parameters such as peaks, troughs, and frequency. As long as the first preset information is consistent with the parameters of the ECG information output by the ECG detection system 100, no limitation is imposed here.

[0068] And because each person's physique is different, their ECG information cannot be exactly the same, and there will be a certain range of fluctuations, that is, the ECG waves of the human body are not fixed, but have a certain floating range. In other words, the peaks, troughs, and frequencies of the ECG waves of different human bodies are different. Therefore, preferably, the first preset information includes the range of peaks, the range of troughs, and the range of frequencies in the ECG information of the human body. When judging whether the subject is a living body (that is, a human body), it is necessary to compare the peaks, troughs, and frequencies in the ECG information of the subject with the peak range, trough range, and frequency range in the first preset information respectively. Only when the peaks, troughs, and frequencies in the ECG information of the subject are respectively within the peak range, trough range, and frequency range in the first preset information, can the subject be judged to be a living body, that is, only when the peaks, troughs, and frequencies all meet the conditions can it be identified as a living body, and only if one or two of the parameters meet the conditions, it cannot be judged as a living body. For example, if only the peaks in the subject's ECG information are within the peak range of the first preset information, the subject cannot be determined to be alive; or if only the troughs in the subject's ECG information are within the trough range of the first preset information and the frequency in the subject's ECG information is within the frequency range of the first preset information, the subject cannot be determined to be alive. Taking specific numbers as an example, the peak range in the first preset information can be set to 4V~7V, the trough range to -2V~1V, and the frequency range to 1Hz~2Hz. When the peak in the subject's electrocardiogram information is detected to be 6V, the trough range is -0.5V, and the frequency range is 0.2Hz, although the peak and trough in the subject's electrocardiogram information are respectively within the peak range and trough range of the first preset information, the frequency in the subject's electrocardiogram information is not within the frequency range of the first preset information, so it is judged that the subject is not a living body; and when the peak in the subject's electrocardiogram information is 6V, the trough range is -0.5V, and the frequency range is 1.2Hz, the peak, trough and frequency in the subject's electrocardiogram information are respectively within the peak range, trough range and frequency range in the first preset information, so it can be judged that the subject is a living body.

[0069] Fingerprint detection module 300 is used to detect the subject's fingerprint information. The fingerprint detection technology here is mature in the existing art and will not be described in detail here. Fingerprint verification module 400 is used to compare the detected subject's fingerprint information with the registered fingerprint information, where the registered fingerprint information is pre-registered by the user in the live fingerprint recognition device. If the subject is alive and the fingerprint information matches the registered fingerprint information, the verification is successful.

[0070] It should be noted that the verification referred to here is specifically based on the comparison of the detected electrocardiogram information with the first preset information by the liveness judgment module 200 and the comparison of the detected fingerprint information with the registered fingerprint information by the fingerprint verification module 400, to determine whether the verification is passed. That is, the verification can only be passed if both conditions are met at the same time: the subject is alive and the detected fingerprint information is consistent with the registered fingerprint information; if only one of the conditions is met, the verification will not pass.

[0071] The present invention combines a liveness judgment module with a fingerprint verification module. Verification can only be passed when both the conditions of the subject being alive and the detected fingerprint information being consistent with the registered fingerprint information are met. This reduces the risk of the fingerprint recognition device being deceived by counterfeit fingerprints and improves the security of the fingerprint recognition device.

[0072] The live fingerprint recognition device provided by the present invention can be used in electronic devices (such as tablets, mobile phones, etc.), access control systems, and other equipment systems that require user identity verification, without limitation here.

[0073] As a preferred embodiment of the present invention, Figure 5 As shown, the fingerprint recognition device may also include: a health detection module 500. After the liveness judgment module 200 determines whether the subject is alive, if the subject is alive, the health detection module 500 compares the detected electrocardiogram information of the subject with the second preset information to determine the health status of the subject; wherein, if the electrocardiogram information of the subject is not within the second preset information range, the subject is in an unhealthy state; wherein, the first preset information range includes the second preset information range. Specifically, the first preset information and the second preset information can be set in the liveness judgment module, or can be set separately in other storage modules, and then retrieved from the storage module when needed. Here, the storage location of the preset biometric information is not limited. And like the first preset information, preferably, the second preset information includes the range of parameters such as peaks, troughs and frequencies in the electrocardiogram information, but the second preset information is not limited to these parameters and is not limited here.

[0074] Accordingly, the first preset information range including the second preset information range specifically means that the peak range in the first preset information includes the peak range in the second preset information, the trough range in the first preset information includes the trough range in the second preset information, and the frequency range in the first preset information includes the frequency range in the second preset information. For example, the peak range in the first preset information is 4V to 7V, the trough range is -2V to 1V, and the frequency range is 1Hz to 2Hz; the peak range in the second preset information is 5V to 6V, the trough range is -1V to 0V, and the frequency range is 1.2Hz to 1.5Hz. When the peak of the subject's electrocardiogram information is detected to be 5V, the trough range is -3V, and the frequency range is 1.4Hz, although the subject's peak and frequency are within the first preset information range, the subject's trough is not within the trough range of the first preset information. Therefore, the subject is judged to be not a living body, and there is no need to judge its health status; when the peak of the subject's electrocardiogram information is detected to be 5.5V, the trough range is -0.5V, and the frequency range is 1.8Hz, the peak, trough and frequency in the subject's electrocardiogram information are all within the range of the first preset information. Therefore, the subject is a living body, and then a health detection step is performed to compare the peak, trough and frequency in the subject's electrocardiogram information with the second preset information respectively. The frequency of the subject is not within the frequency range of the second preset information, so the subject is in an unhealthy state.

[0075] That is, when the device identifies the subject as alive, it can also determine their health status based on the subject's ECG information and provide feedback, allowing the user to promptly understand their physical condition. It should be noted that if the liveness determination module 200 determines that the subject is not alive, then the health detection module 500 is not required to perform a health diagnosis on the subject, thereby saving device power.

[0076] Specifically, due to different physical health conditions of the human body, the range of its ECG information is also different. Therefore, as described in this solution, although the ECG information of the subject is within the first preset information range, that is, although the subject is a living body, it is not necessarily healthy, and the health status needs to be judged using the second preset information. At this time, if the ECG information of the subject is within the second preset information range, the subject is in a healthy state; if the ECG information of the subject is not within the second preset information range, then the subject is in an unhealthy state. Of course, the subject here refers to a living body (that is, a human). If the subject is not a living body, there is no need to discuss whether it is healthy or not.

[0077] As a preferred embodiment of the present invention, Figure 5As shown, the live fingerprint recognition device may further include an alarm module 600. After the health detection module determines that the subject is in a healthy state, the alarm module 600 issues an alarm when the subject is in an unhealthy state. Preferably, the alarm module issues a first alarm when the subject's electrocardiogram information is below a first threshold; and a second alarm when the electrocardiogram information is above a second threshold.

[0078] That is, if the alarm module 600 is not triggered, it indicates that the health status of the subject is normal. Only when the health status is abnormal (that is, when the subject is in an unhealthy state) will the alarm module be triggered. Among them, the alarm can be divided into two forms: a first alarm and a second alarm, and the first alarm is different from the second alarm. Specifically, the first alarm and the second alarm can be voice alarms (the voice content of the two alarms is different), or different light flashing alarms (for example, the first alarm uses a flashing red light to alarm, and the second alarm uses a flashing green light to alarm). As long as different alarm signals can be distinguished, there is no limitation here. In addition, the alarm module 600 can be directly connected to the health detection module 500, or it can be connected to the controller instead of the health detection module 500. When the health detection module 500 detects that the subject is in an unhealthy state, the alarm module 600 is controlled by the controller to alarm.

[0079] The first threshold value and the second threshold value here are respectively the lower limit and the upper limit of the second preset information range, such as the upper and lower limits of the frequency range in the second preset information. Preferably, in the alarm module 600, the first threshold value can be 1.2Hz, and the second threshold value can be 1.5Hz. When the frequency value in the electrocardiogram information of the subject is 1Hz, the alarm module 600 will issue a first alarm, such as a voice prompt that the heart rate is too slow or a red light flashes; when the frequency value in the electrocardiogram information of the subject is 1.8Hz, the alarm module 600 will issue a second alarm, such as a voice prompt that the heart rate is too fast or a green light flashes, etc.

[0080] Because different objects have different ECG signals, especially inanimate objects like fruits, vegetables, wood, and metal, which lack ECG waves, a method for determining whether the subject is human can be used to determine if the subject's ECG signals are close to those of the human body. ECG signals can also directly reflect the health of a person's heart, a vital organ in the human body. Therefore, ECG signals can be used to assist in determining a person's health.

[0081] As a preferred embodiment of the present invention, Figure 5 As shown, the live fingerprint recognition device may further include an activation module 700. When the subject is alive, the activation module 700 is used to activate the fingerprint detection module 300 to detect the fingerprint information of the subject.

[0082] It should be noted that the activation module 700 activates the fingerprint detection module 300 only after the liveness determination module 200 determines whether the subject is alive. That is, only when the subject is detected as alive is the fingerprint detection module 300 activated to detect the subject's fingerprint information. If the subject is not alive, fingerprint detection is not required. In other words, if the subject is not alive, the fingerprint detection module 300 is in a dormant state. This saves power and, to a certain extent, extends the life of the device.

[0083] As a preferred embodiment of the present invention, Figure 5 As shown, the live fingerprint recognition device may also include a contact detection module 800 for detecting the subject's touch before the ECG detection system 100 detects the subject's ECG information. When the subject's touch is detected, the ECG detection system 100 is activated to detect the subject's ECG information. In other words, before the ECG detection system 100 performs detection, the contact detection module 800 can determine whether the subject has touched the device. If not, the ECG detection system 100 remains in a dormant state. Similarly, after providing the contact detection module 800, power can be further saved and the service life of the device can be further extended to a certain extent.

[0084] As a preferred embodiment of the present invention, Figure 5 As shown, the live fingerprint recognition device may further include a storage module 900 for storing registered fingerprint information and / or first preset information before the ECG detection system 100 detects the subject's ECG information. Specifically, the user's pre-registered fingerprint information and / or pre-set first preset information capable of representing human ECG information may be stored in the storage module 900, facilitating the fingerprint recognition module 400 and / or the liveness determination module 200 to retrieve the data in the storage module 900 for data processing and matching.

[0085] The above is merely an example of the specific structure of each module in the live fingerprint recognition device provided by the embodiment of the present invention. In a specific implementation, the specific structure of each module is not limited to the above structure provided by the embodiment of the present invention, and may also be other structures known to those skilled in the art. Again, this is not limited.

[0086] Correspondingly, the present invention also provides a smart door lock, comprising the live fingerprint recognition device provided by the above embodiment of the present invention.

[0087] Accordingly, refer to Figure 6 The specific embodiment of the present invention also provides a live fingerprint recognition method, which specifically includes:

[0088] S1. ECG detection step: detecting the ECG information of the subject.

[0089] Specifically, because each organism has different ECG information, the ECG information can be used as the basis for determining whether the subject is a human body. The ECG information here can be related parameters such as peak information, trough information, and frequency information in the ECG information, which are not limited here.

[0090] S2, a living body determination step, comparing the detected ECG information of the subject with the first preset information to determine whether the subject is alive. If the ECG information of the subject is within the range of the first preset information, the subject is alive.

[0091] Specifically, the first preset information includes the range of parameters such as peaks, troughs and frequencies in the electrocardiogram information. However, the first preset information is not limited to parameters such as peaks, troughs and frequencies. It is sufficient as long as the first preset information is consistent with the parameters in the electrocardiogram information of the subject detected by the electrocardiogram detection system 100.

[0092] S3: fingerprint detection step, detecting the fingerprint information of the subject.

[0093] Specifically, the fingerprint detection step here can be performed using any fingerprint detection technology, such as microwave detection technology, photoelectric information detection technology, etc. Since fingerprint detection technology is currently a relatively mature detection technology, it will not be described in detail here.

[0094] S4, fingerprint verification step, comparing the detected fingerprint information of the subject with the registered fingerprint information, which is pre-registered by the user; wherein, if the subject is alive and the fingerprint information is consistent with the registered fingerprint information, the verification is successful.

[0095] That is, if only one of the following conditions is met: the subject is alive or the detected fingerprint information matches the registered fingerprint information, the verification will fail. Only when both conditions are met: the subject is alive and the detected fingerprint information matches the registered fingerprint information, the verification will pass.

[0096] By combining liveness detection with fingerprint detection, the risk of being deceived by forged fingerprints during fingerprint recognition can be reduced, thereby improving the security of fingerprint recognition.

[0097] As a preferred embodiment of the present invention, the live fingerprint recognition method further comprises, after the liveness determination step, a health detection step, in which, when the subject is alive, the detected electrocardiogram information of the subject is compared with the second preset information to determine the health status of the subject; wherein,

[0098] If the subject's electrocardiogram information is not within the second preset information range, the subject is in an unhealthy state; and the first preset information range includes the second preset information range.

[0099] Specifically, as mentioned above, due to the differences in each person's physique, their ECG information cannot be exactly the same, and there will be a certain range of fluctuations, that is, the parameters such as peaks, troughs, and frequencies in the ECG information of the human body are not fixed values, but have a certain range respectively. In other words, within this range, it can be judged as a human body (living body). However, due to certain reasons, for example, different physical health conditions, the range of its ECG information is also different, that is, as stated in this solution, the health status of the subject can be judged based on the second preset information. If it is within the second preset information range, it is in a healthy state, otherwise it is in an unhealthy state. For specific examples, refer to the example of the second preset information range in the health detection module.

[0100] As a preferred embodiment of the present invention, after the health detection step, the live fingerprint recognition method may further include: an alarm step of issuing an alarm when the subject is in an unhealthy state.

[0101] As a preferred embodiment of the present invention, after the liveness determination step and before the fingerprint detection step, the liveness fingerprint recognition method may further include: an activation step, in which the fingerprint detection step is executed when the subject is alive.

[0102] Specifically, this step is set between the liveness determination step S2 and the fingerprint detection step S3, that is, if the liveness determination step S2 determines that the subject is not alive, the fingerprint detection step S3 is not executed; only when the subject is alive, the fingerprint detection step S3 is continued to be executed.

[0103] As a preferred embodiment of the present invention, before the electrocardiogram detection step S1, the live fingerprint recognition method may further include: a contact detection step of detecting the touch of the subject; when the touch of the subject is detected, executing the electrocardiogram detection step S1.

[0104] This step is provided before the electrocardiogram detection step S1. In other words, the electrocardiogram detection step S1 is executed only when the contact of the subject is sensed.

[0105] As a preferred embodiment of the present invention, before the electrocardiogram detection step S1, the live fingerprint recognition method may further include: a storage step, which is provided before the electrocardiogram detection step S1, and the storage step specifically stores the user's pre-registered registered fingerprint information and / or pre-set first preset information to facilitate the retrieval and processing of data in the liveness determination step and the fingerprint recognition step.

[0106] The living body fingerprint identification device provided by the application adopts the combination of an electrocardio detection system, a living body judgment module, a fingerprint detection module and a fingerprint verification module, and verification can only pass when the two conditions of the detected body being a living body and the detected fingerprint information being consistent with the registered fingerprint information are simultaneously met, so that the risk of false fingerprint deception passing of the fingerprint identification device being counterfeited is reduced, and the security of the fingerprint identification device is improved.

[0107] In addition, the electrocardio detection system in the living body fingerprint identification device adopts two-stage amplification for the electrocardio signals collected by the electrocardio sensor, and performs negative feedback processing on the first-stage amplified signals output by the first amplification module, that is, the impurity signals composed of electrostatic signals caused by friction on the surface of the human body, weak electromagnetic wave signals in the air and the like are filtered out through the negative feedback module, so as to prevent the electrocardio signals from being distorted after the first-stage amplification, and then the first-stage amplified signals are amplified again, and the interference of high-frequency electromagnetic waves and power frequency signals and the like in the second-stage amplified signals is removed through the low-pass filter module, and then the signals processed by the low-pass filter module are converted into digital signals by the analog-digital conversion module, so that more accurate electrocardio signals are obtained.

[0108] Although the application has been illustrated and described with reference to certain preferred embodiments thereof, it should be understood by those skilled in the art that the foregoing is a description of the application in terms of preferred embodiments only and is not intended to limit the application to the specific embodiments illustrated. Various modifications to the application in terms of form and detail can be made without departing from the spirit and scope of the application.

Claims

1. An electrocardiogram detection system, applied to a live fingerprint recognition device, characterized in that: include: An ECG acquisition module includes a first ECG sensor and a second ECG sensor, configured to acquire ECG signals from the thumb and palm of the same hand of a subject to determine whether the subject is alive. The ECG signals are not necessarily complete signals, but include peaks, troughs, and frequency information in the ECG signals. If the peaks, troughs, and frequency information in the ECG signals are respectively within the peak range, trough range, and frequency range specified in first preset information, the subject is alive. a first amplifying module, configured to receive the ECG signal collected by the ECG collecting module, amplify the ECG signal, and output a first-level amplified signal; a negative feedback module, connected in parallel with the first amplification module, configured to filter out impurity signals in the first-stage amplified signal and maintain a stable output of the first-stage amplified signal; a second amplifying module, receiving the first-stage amplified signal, amplifying the first-stage amplified signal, and then outputting a second-stage amplified signal; A low-pass filter module receives the secondary amplified signal and processes and outputs it; The analog-to-digital conversion module receives the processed signal output by the low-pass filtering module, converts the processed signal into a digital signal, and then outputs the electrocardiogram information of the subject.

2. The electrocardiogram detection system according to claim 1, wherein: The negative feedback module includes: a third resistor, a fourth resistor, a ninth resistor, a first capacitor and a third operational amplifier; wherein, The positive phase input terminal of the third operational amplifier is connected to the second amplifying module, the negative phase input terminal of the third operational amplifier is connected to the second end of the ninth resistor and the second end of the first capacitor respectively, and the output terminal of the third operational amplifier is connected to the first end of the first capacitor and the first amplifying module respectively; The first end of the third resistor is connected to the first amplifying module and the electrocardiogram acquisition module respectively, and the second end of the third resistor is connected to the second end of the fourth resistor and the non-inverting input end of the third operational amplifier respectively; The first end of the fourth resistor is connected to the first amplifying module and the electrocardiogram acquisition module respectively; The first end of the ninth resistor is connected to the first amplifying module and the second amplifying module respectively.

3. The electrocardiogram detection system according to claim 2, wherein: The negative feedback module further includes: a seventh resistor, an eighth resistor and a fourth capacitor; wherein, The first end of the seventh resistor is connected to the power supply terminal, and the second end of the seventh resistor, the first end of the eighth resistor and the first end of the fourth capacitor are all connected to the non-inverting input terminal of the third operational amplifier; The second end of the eighth resistor and the second end of the fourth capacitor are both connected to the ground.

4. The electrocardiogram detection system according to claim 1, wherein: The first amplifying module is an operational amplifier of model AD627.

5. The electrocardiogram detection system according to claim 1, wherein: Also includes: A digital filtering module is connected to the analog-to-digital conversion module.

6. The electrocardiogram detection system according to claim 1, wherein: The second amplification module specifically includes: a fifth resistor, a sixth resistor, a second operational amplifier and a second capacitor; wherein, The positive phase input terminal of the second operational amplifier is connected to the negative feedback module, the negative phase input terminal of the second operational amplifier is respectively connected to the second end of the fifth resistor, the first end of the sixth resistor, and the first end of the second capacitor, and the output terminal of the second operational amplifier is connected to the low-pass filtering module for outputting the secondary amplified signal; The first end of the fifth resistor is connected to the first amplifying module, and is used to receive the first-stage amplified signal; The second end of the sixth resistor is connected to the second end of the second capacitor and the output end of the second operational amplifier respectively.

7. The electrocardiogram detection system according to claim 1, wherein: The low-pass filter module specifically includes: a tenth resistor and a third capacitor, wherein: The first end of the tenth resistor is connected to the second amplification module for receiving the secondary amplified signal, and the second end of the tenth resistor and the first end of the third capacitor are both connected to the analog-to-digital conversion module for outputting the processed signal; The second end of the third capacitor is connected to the ground end.

8. The electrocardiogram detection system according to claim 1, wherein: The amplification factor of the second amplification module is 25 to 50 times that of the first amplification module.

9. The electrocardiogram detection system according to claim 1, wherein: Also includes: a first resistor and a second resistor; The first end of the first resistor is connected to the ECG acquisition module, and the second end of the first resistor is connected to the first amplification module; The first end of the second resistor is connected to the electrocardiogram acquisition module, and the second end of the second resistor is connected to the first amplification module.

10. A live fingerprint recognition device, characterized in that: include: The electrocardiogram detection system according to any one of claims 1 to 9, used to detect electrocardiogram information of a subject; a living body determination module, configured to compare the detected electrocardiogram information of the subject with first preset information to determine whether the subject is alive; If the electrocardiogram information of the subject is within the first preset information range, the subject is alive; A fingerprint detection module, configured to detect fingerprint information of the subject; a fingerprint verification module, configured to compare the detected fingerprint information of the subject with registered fingerprint information, the registered fingerprint information being pre-registered by the user in the live fingerprint recognition device; If the subject is alive and the fingerprint information of the subject is consistent with the registered fingerprint information, the verification is successful.

11. The device according to claim 10, wherein The system further comprises: a health detection module, configured to, after the living body judgment module judges whether the subject is alive, compare the electrocardiogram information of the subject with second preset information to judge the health status of the subject when the subject is alive; wherein, If the electrocardiogram information is not within the second preset information range, the subject is in an unhealthy state; and the first preset information range includes the second preset information range.

12. The device according to claim 11, wherein Also includes: The alarm module is used to issue an alarm when the subject is in an unhealthy state after the health detection module determines the health state of the subject.

13. The device according to claim 10, wherein Also includes: The activation module is configured to activate the fingerprint detection module to detect the fingerprint information of the subject after the liveness judgment module determines whether the subject is live and before the fingerprint detection module detects the fingerprint information of the subject, if the subject is live.

14. The device according to claim 10, wherein Also includes: The contact detection module is used to detect the touch of the subject before the electrocardiogram detection system detects the electrocardiogram information of the subject, and activate the electrocardiogram detection system when the touch of the subject is detected.

15. The device according to claim 10, wherein Also includes: The storage module is used to store the registered fingerprint information and / or the first preset information before the electrocardiogram detection system detects the electrocardiogram information of the subject.

16. A smart door lock, characterized in that: The device comprises a live fingerprint recognition device as claimed in any one of claims 10 to 15.

17. A method for identifying live fingerprints, characterized in that: include: An electrocardiogram (ECG) detection step is to collect ECG signals from the thumb and palm of the same hand of the subject, wherein the ECG signals are not necessarily complete signals and include peaks, troughs, and frequency information in the ECG signals; a living body determination step of comparing the detected electrocardiogram information of the subject with first preset information to determine whether the subject is alive; If the peak, trough and frequency information of the electrocardiogram information of the subject are respectively within the peak range, trough range and frequency range in the first preset information, the subject is alive; A fingerprint detection step of detecting fingerprint information of the subject; a fingerprint verification step of comparing the detected fingerprint information of the subject with registered fingerprint information, the registered fingerprint information being pre-registered by the user; If the subject is alive and the fingerprint information of the subject is consistent with the registered fingerprint information, the verification is successful.

18. The method according to claim 17, wherein After the living body determination step, the method further includes: The health detection step, when the subject is alive, compares the electrocardiogram information of the subject with second preset information to determine the health status of the subject; wherein, If the electrocardiogram information is within the second preset information range, the subject is in an unhealthy state; and the first preset information range includes the second preset information range.

19. The method according to claim 18, wherein After the health detection step, the method further includes: The alarm step is to issue an alarm when the subject is in an unhealthy state.

20. The method of claim 17, wherein: After the liveness determination step and before the fingerprint detection step, the method further includes: The activation step is to execute the fingerprint detection step when the subject is alive.

21. The method according to claim 17, wherein Before the electrocardiogram detection step, the method further includes: The contact detection step detects the touch of the subject, and when the touch of the subject is detected, the electrocardiogram detection step is executed.

22. The method of claim 17, wherein: Before the electrocardiogram detection step, the method further includes: The storage step is used to store the registered fingerprint information and / or the first preset information.

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