Biometric authentication system, authentication terminal, and authentication method

Abstract

In a general portable information terminal, a true operator is prompted to present his or her own biological information, and authentication is performed. A biological authentication system has a photographing section that acquires first image data and second image data obtained by photographing different biological regions of an operator during a predetermined period, a display section that displays a guide for guiding the positions of the biological regions of the operator in order to photograph the different biological regions of the operator, and a storage section that stores biological authentication information of the operator in advance. Furthermore, first vital sign information and second vital sign information are extracted from the image data of the different biological regions, respectively, the identity of the operator is determined based on the first vital sign information and the second vital sign information, the biological authentication information of the operator is extracted from the second image data in a case where the identity of the operator is confirmed, and biological authentication is performed based on the extracted biological authentication information and the biological authentication information stored in the storage section.

Description

TECHNICAL FIELD

[0001] The present application relates to a technology for authenticating a person using a living body. BACKGROUND

[0002] In the past, as a personal authentication means for access management such as entrance control into a room, time attendance, and login to a computer, a stored authentication such as ID (Identification) and PW (Password) and an object authentication such as a physical lock or an IC (Integrated Circuit) card have been widely used.

[0003] However, there is a risk of forgetting or losing in these authentications. In contrast, in recent years, a living body authentication that does not have such a risk has been utilized. In the living body authentication, a device equipped with a sensor for reading living body information is used for all access management for a PC (Personal Computer), a bank ATM (Automated Teller Machine), an entrance of a room, or a locker, and the like. In particular, in recent years, with the spread of portable information terminals such as smartphones and tablet computers, examples of simply performing a living body authentication on a portable information terminal have increased. On the other hand, examples of performing a living body authentication by another person impersonating oneself by presenting a photo that reflects a living body, a display, an object that imitates a living body, and the like have become a problem. Therefore, in order to enable a user to safely and securely perform a living body authentication, a means for preventing such impersonation is required.

[0004] In Patent Literature 1, a technology is disclosed in which vital sign information is extracted from a face region of a person in time-sequentially captured images obtained by an imaging device, and based on the vital sign information, fraud caused by a photo of the person or the like is prevented.

[0005] PRIOR ART DOCUMENT

[0006] PATENT LITERATURE

[0007] Patent Literature 1: Japanese Patent Application Publication No. 2017-10210 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] In Patent Literature 1, there is a problem that by displaying a dynamic image that reflects a person on a display and presenting it to an authentication terminal, another person can easily impersonate the person to perform a living body authentication.

[0010] Therefore, an object of the present application is to provide a biological authentication system and method in which an operator can confirm that the operator is prompted for biological information of the operator and performs authentication of the operator on a general portable information terminal.

[0011] Means for solving the problem

[0012] To achieve the above object, one embodiment of the biological authentication system of the present application has: a photographing section that acquires first image data and second image data obtained by photographing different biological regions of an operator within a prescribed period; a display section that displays guidance for guiding an operator to positions of the biological regions in order to photograph the different biological regions of the operator; a storage section that stores biological authentication information of the operator in advance; and an authentication processing section that extracts first vital sign information and second vital sign information from the first image data and the second image data of the different biological regions, respectively, determines the identity of the operator based on the first vital sign information and the second vital sign information, extracts biological authentication information of the operator from the second image data in a case where the identity of the operator is confirmed, and performs biological authentication based on the extracted biological authentication information and the biological authentication information stored in the storage section.

[0013] Effects of the Invention

[0014] According to the present application, in a case where it is possible to confirm the identity of a plurality of vital sign information obtained from different biological regions of a plurality of biological parts acquired from a general portable terminal having a photographing section that acquires image data, an operator can perform biological authentication based on biological information of the operator. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 FIG. 1 is a diagram showing an example of a functional block diagram of the biological authentication system of Embodiment 1.

[0016] Figure 2 FIG. 2 is a diagram showing an example of a functional block diagram of the authentication processing section 2 of Embodiment 1.

[0017] Figure 3 FIG. 3 is a diagram showing an example of a case where the authentication is observed from the back side of the authentication terminal of Embodiment 1.

[0018] Figure 4 FIG. 4 is a diagram showing an example of a case where the authentication is observed from the front side of the authentication terminal of Embodiment 1.

[0019] Figure 5 FIG. 5 is a flowchart showing the processing at the time of registration of Embodiment 1.

[0020] Figure 6 FIG. 6 is a flowchart showing the processing at the time of authentication of Embodiment 1.

[0021] Figure 7 is a drawing showing an example of the screen display of the guidance of the body part to the photographing section arranged on the back of the authentication terminal in Embodiment 1.

[0022] Figure 8 is a drawing showing an example of the screen display of the guidance of the body part to the photographing section arranged on the front of the authentication terminal in Embodiment 1.

[0023] Figure 9 is a flowchart showing the process of the confirmation determination S101 of the operation explanation in Embodiment 1.

[0024] Figure 10 is a drawing showing an example of the screen display in the confirmation determination S101 of the operation explanation in Embodiment 1.

[0025] Figure 11 is a drawing showing an example of the operation mode of the authentication terminal in the confirmation determination S101 of the operation explanation in Embodiment 1.

[0026] Figure 12 is a drawing showing an example of the screen display in the guidance of the posture S102 in Embodiment 1.

[0027] Figure 13 is a drawing showing the generation method of the vital sign information displayed in the guidance of the posture S102 in Embodiment 1.

[0028] Figure 14 is a flowchart showing the process of the acquisition S103 of the body authentication information and the vital sign information in Embodiment 1.

[0029] Figure 15 is a drawing showing an example of the case where the photographing is performed with the whole lens shielded by the finger and the obtained dynamic image in the quality determination S104 of the acquired information in Embodiment 1.

[0030] Figure 16 is a drawing showing an example of the case where the photographing is performed with only a part of the lens shielded by the finger and the obtained dynamic image in the quality determination S104 of the acquired information in Embodiment 1.

[0031] Figure 17 is a drawing showing an example of the observation of the authentication from the back side of the authentication terminal in Embodiment 2.

[0032] Figure 18 is a drawing showing an example of the observation of the authentication from the front side of the authentication terminal in Embodiment 2.

[0033] Figure 19 is a drawing showing an example of the observation of the authentication from the back side of the authentication terminal in Embodiment 3.

[0034] Figure 20 is a view showing an example of the authentication situation from the front side of the authentication terminal of Embodiment 3.

[0035] Figure 21 is a view showing an example of the authentication situation of Embodiment 4. DETAILED DESCRIPTION

[0036] In the following description, the authentication processing section is constituted by one or more processors. The at least one processor is typically a microprocessor such as a CPU (Central Processing Unit), but can be another kind of processor such as a GPU (Graphics Processing Unit). The at least one processor can be a single core or a plurality of cores.

[0037] Further, the at least one processor can also be a general-purpose processor that performs part or all of the processing, such as a hardware circuit (for example, an FPGA (Field-Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit)).

[0038] In addition, in the following description, the subject of the processing is sometimes described as a program, but the program is executed by the processor, and thus the determined processing is appropriately performed using the storage section and / or the interface section and the like, and thus the subject of the processing can also be the processor (or a device such as a controller having the processor).

[0039] The program can be installed in a device such as a computer, and for example, can be located on a program distribution server or a computer-readable (for example, non-transitory) recording medium. In addition, in the following description, two or more programs can be implemented as one program, or one program can be implemented as two or more programs.

[0040] In addition, the biological authentication system can be a distributed system constituted by one or more (typically, a plurality of) physical devices.

[0041] In addition, in the following description, in the case of describing the same elements without distinguishing them, a reference sign (or a common sign in the reference sign) is sometimes used, and in the case of describing the same elements with distinguishing them, an identification number (or a reference sign) of the element is sometimes used.

[0042] Hereinafter, various embodiments of the present application will be described with reference to the accompanying drawings. In addition, the drawings show specific embodiments following the principles of the present application, but these are for understanding the present application and are not intended to be limitatively explained.

[0043] Embodiment 1

[0044] Figure 1 is a drawing showing an example of a block diagram of the structure of the biometric authentication system of Embodiment 1.

[0045] In the embodiment, the biometric authentication system is described as a general portable terminal such as a smartphone, a tablet, or the like, that is, an authentication terminal 100, but the present application is not only configured as the authentication terminal 100, but of course can be configured as a biometric authentication device including the authentication processing. Figure 1 In this case, the biometric authentication system of the present application can also be a biometric authentication device including the authentication processing. Alternatively, the authentication processing can be performed outside the authentication terminal, and the authentication terminal can be configured to be dedicated to acquisition of a biometric image.

[0046] The authentication terminal 100 of Embodiment 1 includes a photographing section 1, an authentication processing section 2, a storage section 3, a display section 4, an input section 5, a posture detection section 6, and a vibration section 7, a sound output section 8.

[0047] The photographing section 1 is, for example, a camera, and acquires an image including biometric authentication information by photographing an authentication target (an operator of the authentication terminal), and inputs the acquired image to the authentication processing section 2. The camera has, for example, three light receiving elements having sensitivities with respect to blue (B), green (G), and red (R), respectively, and these light receiving elements are arranged in a lattice shape for each pixel. The spectral sensitivity of each light receiving element has, for example, a peak value of sensitivity near 480 nm for blue, near 550 nm for green, and near 620 nm for red. By photographing using the camera, a spatial luminance distribution of light having a peak value of sensitivity at each of the three different wavelengths can be obtained.

[0048] The authentication processing section 2 generates biometric authentication information by performing image processing on the image input from the photographing section 1, and performs authentication processing based on the biometric authentication information. In addition, the photographing section 1 can be included in the authentication processing section 2 to configure an image processing section in some cases. In any case, the authentication processing section 2 has an image processing function.

[0049] The authentication processing section 2 includes a central processing unit (CPU) 9, a memory 10, and various interfaces 11 (IF). The CPU 9 performs various processes by executing a program stored in the memory 10. The memory 10 stores the program executed by the CPU 9. In addition, the memory 10 temporarily stores an image input from the photographing section 1. The interfaces 11 connect the authentication processing section 2 with external devices. Specifically, the interfaces 11 are connected with the photographing section 1, the storage section 3, the display section 4, the input section 5, the posture detection section 6, the vibration section 7, the sound output section 8, and the like.

[0050] Figure 2 Fig. 1 is a functional block diagram of the authentication processing section 2 of Embodiment 1.

[0051] The authentication processing section 2 includes an authentication section 12 and a registration section 13. The authentication section 12 and the registration section 13 are realized by the CPU 9 executing a program stored in the memory 10. The authentication section 12 performs authentication of a user by collating biological authentication information (hereinafter, sometimes referred to as input data) obtained by performing image processing on an image input from the photographing section 1 with biological authentication information (hereinafter, sometimes referred to as registration data) registered in advance in the storage section 3. The registration section 13 generates the registration data from an image acquired by the photographing section 1 and stores it in the storage section 3 in advance.

[0052] Returning to Figure 1 , the storage section 3 stores registration data of a user in advance. The registration data (biological authentication information) is information used for collation of a user, such as an image of a finger vein pattern, a feature amount of a nose, eyes, a mouth, and the like used in face recognition, and the like. Generally, the image of the finger vein pattern is an image in which blood vessels (finger veins) distributed in the subcutaneous layer on the palm side of a finger are photographed as a shadow pattern.

[0053] The display section 4 is, for example, a display that outputs information received from the authentication processing section 2 in the form of an image. In the following description, the display section 4 is sometimes referred to as the display 4. In order to photograph different biological regions of an operator, the display section 4 displays a guide that guides the operator to one biological region. The input section 5 is, for example, a keyboard that inputs information input by a user to the authentication processing section 2. The so-called keyboard can be either a physical keyboard in which buttons for inputting characters or numbers by physical pressing are arranged or a virtual keyboard in which an image simulating a physical keyboard is displayed in the display 4 and buttons on the image simulating the keyboard are pressed by a pointing device such as a mouse, a touch panel, a pen, or the like. In the following description, the input section 5 is sometimes referred to as the keyboard 5 or the button 5.

[0054] The posture detection section 6 is, for example, a gyro sensor, an acceleration sensor, a geomagnetic sensor, or the like, and detects information on the motion, orientation, or the like of a part or the whole of the authentication terminal 100, and inputs the information to the authentication processing section 2. The vibration section 7 is, for example, a linear resonant actuator, and vibrates a part or the whole of the authentication terminal 100. The sound output section 8 is, for example, a speaker, and outputs information received from the authentication processing section 2 in the form of sound. In the following description, the sound output section 8 is sometimes referred to as the speaker 8.

[0055] Figure 3 An example of observing the authentication status from the back side of the authentication terminal 100 in Embodiment 1 is shown.

[0056] Figure 4 An example of observing the authentication status from the front side of the authentication terminal 100 in Embodiment 1 is shown.

[0057] In Embodiment 1, the authentication terminal 100 provided with the rear camera 14 and the front camera 15 on the outside of the housing 16, and the display 4 performs biometric authentication after confirming that the operator of the authentication terminal is the authenticator himself / herself assumed by the biometric authentication system.

[0058] As shown in Figs. 1 and 2, the authentication terminal 100 is provided with the display 4, the rear camera 14, the front camera 15, the posture detection section 6, the vibration section 7, and the sound output section 8. Figure 3 and Figure 4 The operator of the authentication terminal is instructed by the display 4 to be described later, and is prompted to hold the finger 17 and the face 18 confirming the screen of the terminal, as shown in Figs. 3 and 4. The authentication terminal 100 captures the finger 17 by the rear camera 14 disposed on the back of the housing 16 of the authentication terminal 100, and captures the face 18 by the front camera 15 disposed on the front of the housing 16 of the authentication terminal 100. Vital sign information A is extracted from the image obtained by the rear camera 14, and vital sign information B of the operator and biometric authentication information of the operator are extracted from the image obtained by the front camera 15.

[0059] The vital sign information A extracted from the image of the rear camera 14 is, for example, a pulse wave of the hand or the finger 17, and the vital sign information B obtained from the front camera 15 is, for example, a pulse wave of the face 18. In addition, the biometric authentication information extracted from the image of the front camera 15 is, for example, a feature amount of the nose, the eyes, the mouth, or the like of the face 18 used in face recognition technology.

[0060] In Embodiment 1, the fact that the vital sign information such as the pulse wave acquired during a predetermined period is from the same person is confirmed by the rear camera 14 and the front camera 15, whereby impersonation of the operator can be prevented. In addition, after the identity of the operator is confirmed, biometric authentication can be performed by biometric authentication information prompted by the operator of the authentication terminal. In addition, the predetermined period means that the vital sign information A and the vital sign information B are acquired by the rear camera 14 and the front camera 15 at the same timing. With respect to the same timing, the vital sign information can be acquired at different timings as long as it is during the authentication processing. In this way, the period during which two vital sign information are acquired for authentication is referred to as an authentication period, and when biometric authentication information is registered, it is referred to as a registration period. The authentication period and the registration period are predetermined periods, and for example, can be set to an arbitrary time such as 10 seconds.

[0061] Figure 5 is a flowchart showing the processing at the time of registration in the authentication terminal 100 of Embodiment 1. With respect to the processing shown in Figure 5 , the processing is performed by the control of the authentication processing section 2.

[0062] First, the authentication terminal 100 explains the authentication method to the operator of the authentication terminal 100 using the display 4 and the speaker 8 (S100).

[0063] Next, the authentication terminal 100 confirms whether the operator has understood the explanation of the authentication method using the input section 5 and the posture detection section 6 (S101).

[0064] Next, the authentication terminal 100 displays an image in which a sample of a living body to be prompted as a living body part is simulated, a moving image obtained from the photographing section 1 described later, biometric authentication information extracted from the moving image, and a character indicating a specific prompt posture in the display 4 (S102).

[0065] Next, during the registration period, the authentication terminal 100 photographs the living body part of the operator using the rear camera 14 and the front camera 15 as the photographing section 1, and acquires vital sign information and biometric authentication information from the obtained moving image (S103). That is, vital sign information such as a pulse wave is acquired from the rear camera 14 and the front camera 15, and biometric authentication information such as a feature amount of the nose, the mouth, the eyes, and the like used in face authentication technology is acquired from the front camera 15.

[0066] Next, the authentication processing section 2 determines whether the quality of the vital sign information extracted from the dynamic images acquired from the rear camera 14 and the front camera 15, and the biometric authentication information extracted from the dynamic images acquired from the front camera 15 is appropriate (S104). In a case where it is determined that the quality is low and inappropriate, the indication of the prompting posture is instructed (S102) in order to improve the quality, and the biometric authentication information is newly acquired (S103). In a case where it is determined that the quality is high and appropriate, the next process is entered.

[0067] Next, the authentication processing section 2 determines whether there is impersonation by another person based on the acquired dynamic images obtained by photographing the face 18 and the finger 17 (S105). The determination of the impersonation (S105) is a process of confirming the identity of the operator. Specifically, the vital sign information A and the vital sign information B acquired by the rear camera 14 and the front camera 15, respectively, are stored in the memory 10. Then, the authentication section 12 compares the vital sign information A and the vital sign information B stored in the memory 10 to make a determination. For example, with respect to the vital sign information A and the vital sign information B acquired simultaneously from different biometric parts, respectively, the amplitude, the period, the phase, and the like are calculated. If these vital sign information are acquired from the same person, the period corresponding to the number of heartbeats is sufficiently small in the difference between the vital sign information A and the vital sign information B, and it is determined that there is no impersonation.

[0068] In addition, in a case where there is a large difference in the period, it is determined that the vital sign information A and the vital sign information B are collected by different persons, and the operator impersonates the biometric authentication subject. In addition, after the determination of the impersonation, the vital sign information A and the vital sign information B stored in the memory 10 are deleted from the memory 10.

[0069] In a case where it is determined that there is impersonation by another person, the display 4 displays a meaning that the registration has failed, and the registration process is ended (S111). In a case where it is determined that there is no impersonation by another person, the next process is entered.

[0070] Next, the authentication processing section 2 temporarily holds the data of the extracted biometric authentication information as a registration candidate in the memory 10 (S106).

[0071] Next, the authentication processing section 2 confirms whether the number of the registration candidate data saved in the memory 10 satisfies a number set in advance (S107). In a case where the number of the registration candidate data is insufficient, the indication of the prompting posture is returned (S102), and the photographing is continued. In a case where the number of the registration candidate data is sufficient, the next process is entered.

[0072] Next, the authentication processing section 2 calculates the degree of difference between the registration candidate data added in step S106 (between the plurality of biometric authentication information) (S108).

[0073] Next, the authentication processing section 2 confirms whether the calculated degree of difference is lower than a registration threshold value set in advance (S109). In the case where the threshold value is exceeded, the display 4 displays a meaning that registration has failed, the registration candidate data temporarily held in the memory 10 is discarded, and the registration processing is ended (S111). In the case where the threshold value is not exceeded, the display 4 displays a meaning that registration has succeeded, the registration candidate data temporarily held in the memory 10 is saved in the storage section 3, and the registration processing is ended (S110).

[0074] Further, in the storage section 3, the biometric authentication information of the same operator is stored in correspondence with the ID uniquely identifying the operator. Therefore, in the explanation of the authentication method in step S100, the input of the ID of the operator can also be instructed.

[0075] Figure 6 is a flowchart showing the processing at the time of authentication of the authentication terminal 100 of Embodiment 1. With regard to the processing shown in Figure 6 , the processing is performed by the control of the authentication processing section 2.

[0076] The instruction of the prompt posture (S102), the acquisition of the vital sign information and the biometric authentication information (S103), the quality determination of the acquired information (S104), the impersonation determination (S105), and the degree of difference calculation (S112) in the processing flow at the time of authentication are the same as those in the processing flow at the time of registration shown in Figure 5 .

[0077] In the acquisition of the vital sign information and the biometric authentication information in step S103, the images of the fingers 17 and the face 18 of the operator of the authentication terminal 100 are acquired by the two cameras of the rear camera 14 and the front camera 15 of the imaging section 1 of the authentication terminal 100, and the vital sign information A and the vital sign information B are acquired from different images at the same timing. The same timing is, except in the case where the vital sign information A and the vital sign information B are acquired at the same time, as long as the period during which the authentication processing is performed, and can also be acquired at different timings. In this way, the period during which the two vital sign information are acquired for authentication is referred to as an authentication period. The authentication period is a predetermined period, and can be set to an arbitrary time such as 10 seconds or the like.

[0078] After the impersonation determination (S105), the authentication processing section 2 calculates the degree of difference between the biometric authentication information extracted from the image captured by the imaging section 1 and the biometric authentication information of the operator registered in the storage section 3 in advance (S112). Therefore, in the instruction of the prompt posture (S102), the input of the ID of the operator is instructed, the input of the ID of the operator is accepted, and the biometric authentication information registered in correspondence with the ID of the operator is read out from the storage section 3.

[0079] Next, the authentication processing section 2 confirms whether the calculated degree of difference is lower than the authentication threshold value set in advance (S113). In the case where the threshold value is exceeded, the meaning of authentication failure is displayed on the display 4, and the authentication processing is ended (S115). In the case where the threshold value is not exceeded, the meaning of authentication success is displayed on the display 4, and the authentication processing is ended (S114).

[0080] Figure 7 is a drawing representing an example of the screen display of the guidance of the guidance of the prompting of the living body part to the rear camera 14 of the authentication terminal 100 in step S100 of Example 1.

[0081] Figure 8 is a drawing representing an example of the screen display of the guidance of the prompting of the living body part to the front camera 15 of the authentication terminal 100 in step S100 of Example 1.

[0082] In the explanation of the operation method (S100), in order to mainly represent which living body part of the operator is prompted at which position of the authentication terminal 100, the image 19 representing an example of the prompting of the living body part, the message 20 representing the method of the prompting of the living body part are displayed on the display 4. In addition, the content of the message 20 can also be read by the speaker 8.

[0083] Figure 9 is a flowchart representing the processing of the confirmation determination S101 of the operation explanation of the authentication terminal 100 of Example 1. Figure 9 The processing illustrated is processed by the control of the authentication processing section 2.

[0084] Figure 10 is a drawing representing an example of the screen display in the confirmation determination S101 of the operation explanation of the authentication terminal 100 of Example 1.

[0085] Figure 11 is a drawing representing an example of the operation situation of the authentication terminal in the confirmation determination S101 of the operation explanation of the authentication terminal 100 of Example 1.

[0086] The confirmation determination of the operation explanation (S101) is processing for causing the operator of the authentication terminal to reliably confirm the operation method explained by the authentication terminal 100, and hereinafter, an example of the detailed content of the description processing will be described. Figure 9

[0087] First, the authentication terminal 100 instructs the operator of the authentication terminal by displaying on the display section 4 to confirm the prompted position of the living body part with respect to the authentication terminal (S1010). For example, as illustrated in Figure 10 ​As shown, the display 4 shows an image 19 representing the back of the authentication terminal 100, a message 20 indicating the location of the camera, and a button 5 indicating to the authentication terminal 100 that the confirmation is complete. Before the operator reads the message 20, the button 5 is set to an inactive state, making it unpressable.

[0088] Next, the authentication terminal 100 detects changes in its posture via the posture detection unit 6 (S1011). For example, as... Figure 11 As shown, the authentication terminal 100 detects the rotation caused by flipping the terminal, thus enabling it to determine if the operator has confirmed the position of the rear camera 14 located on the back of the authentication terminal 100. Alternatively, it can detect changes in the posture of the authentication terminal 100 and clearly display the confirmation of the biological part's position to the operator on a display 4 or similar device. If the change in posture is sufficiently small, the confirmation of the biological part's position is repeated (S1010). Upon detecting a change in posture, the authentication terminal 100 activates and presses button 5 (S1012).

[0089] Next, the authentication terminal 100 checks whether the confirmation button 5 has been pressed (S1013). If it has not been pressed, it remains in standby mode until it is pressed. If it is pressed, it is considered that the terminal operator has finished confirming the explanation of the operation method, and the process ends (S1014).

[0090] Figure 12 This is a diagram illustrating an example of the screen display in the instruction S102 for the prompting posture in Embodiment 1.

[0091] Figure 13 This is a diagram illustrating the method for generating vital sign information displayed in the prompting posture instruction S102 of Embodiment 1.

[0092] Figure 5 The indication of the prompting posture (S102) is a process for high-precision detection of impersonation or implementation of biometric authentication. The following is an example of the details of the process.

[0093] The authentication terminal 100 captures an image of the operator's finger 17 using a rear-facing camera 14, and extracts vital sign information A from the captured dynamic image using methods described later. Vital sign information A includes, for example, pulse waves, heart rate, and related temporally continuous signals. The extracted vital sign information A23 is, for example, a waveform image 21 (see reference) representing a waveform with time as the horizontal axis and signal intensity as the vertical axis. Figure 12The image 22, which reflects the face captured by the front-facing camera 15, is displayed on the display 4. Alternatively, pseudo-vital sign information 26, which has different amplitude, period, phase, and other characteristics than the extracted vital sign information A23, can be displayed instead of the waveform image 21. This is because the extracted vital sign information A23 is used to verify whether the operator of the authentication terminal 100 and the person being authenticated for biometric authentication are the same person, as described later; therefore, directly displaying the extracted vital sign information A23 would increase security risks.

[0094] In addition, such as Figure 13 As shown, the extracted vital sign information A23 can also be separated into signal component 24 and noise component 25, and the noise component 25 can be added to the pseudo vital sign information 26 to generate pseudo vital sign information 27 containing noise and interference, which can then be displayed as waveform image 21 instead. This is because by informing the operator of the degree of noise and interference in the extracted vital sign information A23, and displaying the finger prompting method used to reduce interference as message 20, the finger prompting posture can be improved. Thus, it is expected that reducing a portion of the noise and interference components 25 contained in the extracted vital sign information A23 can improve the accuracy of the spoofing detection described later. Here, the absolute value of the difference between the extracted vital sign information A23 and its time average can be easily calculated as the noise component 25 in the extracted vital sign information A23.

[0095] Figure 14 This is a flowchart illustrating the process of obtaining vital sign information and biometric authentication information by the authentication terminal 100 of Embodiment 1, S103. Figure 14 The process shown is handled by the control of the authentication processing unit 2.

[0096] In the acquisition of vital sign information and biometric authentication information (S103), the rear camera 14 captures a picture of the finger 17 holding the terminal, and the front camera 15 captures a picture of the operator's face 18. Vital sign information A is obtained from the dynamic image A obtained from capturing the finger 17, and vital sign information B and biometric authentication information are obtained from the dynamic image B obtained from capturing the face 18. Since vital sign information B and biometric authentication information are obtained from the same data, when it is verified by the method described later that vital sign information A and vital sign information B come from the same person, it is possible to confirm that the biometric authentication information is extracted from the biological part indicated by the real operator who has never been impersonated. In addition, by simultaneously acquiring dynamic image A and dynamic image B and extracting vital sign information A and vital sign information B, the influence of time changes in vital sign information such as pulse wave and heart rate can be reduced. The following is an example of the detailed processing.

[0097] First, the authentication terminal 100 captures the finger 17 in contact with the rear camera 14 as a first camera, acquires a dynamic image A (S1031). By capturing the finger while the fleshy part of the fingertip is in contact with the lens of the rear camera 14, the change in blood flow accompanying the pulsation of the heart can be captured as a change in the brightness of the image. In addition, in a case where a light-emitting device, such as a welding torch, is present in the vicinity of the rear camera 14, the capturing can also be performed while the light-emitting device is lit. By this, the light emitted from the light-emitting device scatters in the finger, and thus the visibility of the blood vessels based on the rear camera 14 is improved, and the change in blood flow of the fingertip can be measured more finely.

[0098] Next, the authentication terminal 100 acquires vital sign information A from the dynamic image A acquired by the rear camera 14, and stores it in the memory 10 (S1032). For example, a 1-dimensional brightness signal in the time direction, which is the average value of the spatial direction of the brightness of each image per unit time constituting the dynamic image A, can be acquired as the vital sign information A. In a case where the images constituting the dynamic image A are RGB images, the signal value of the pixel of green (G) having a larger number of pixels of the light-receiving element and a higher S / N ratio than red (R) and blue (B) can be the brightness of the pixel. Alternatively, the RGB images can be converted into other color spaces such as YUV or HSV, and if it is YUV, Y can be the brightness, and if it is HSV, V can be the brightness signal. Alternatively, the average value of the pixel values of R and G, B of each pixel can be the brightness of the pixel. Here, the vital sign information A described above, like the blood flow of the fingertip, periodically repeats that the brightness signal becomes larger or smaller, but due to disturbances such as pressing or moving the finger during capturing, sometimes a disturbance is generated in the vital sign information A. In order to reduce the influence of the disturbance, the average value of the brightness signal in an interval of time of a certain summary in the vital sign information A, which is a brightness signal continuous in time, can be acquired, and the value can be the vital sign information A.

[0099] Next, the authentication terminal 100 captures the face 18 prompted in the front camera 15 by the front camera 15 as the second camera, acquires a dynamic image B (S1033). Vital sign information B is acquired from the dynamic image B, and stored in the memory 10 (S1034). Then, according to the dynamic image B, the position and size of the face 18 are detected by an arbitrary face detection algorithm, and respective feature amounts and the like are acquired as biometric authentication information, and stored in the memory 10 (S1035). The acquisition of the biometric authentication information can be performed simultaneously with the processing of acquiring the dynamic image A (S1031) from the back camera 14 and acquiring the vital sign information A (S1032), and in particular, in a case where there is a constraint between the maximum data transfer amount between the back camera 14 and the authentication processing unit 2, the front camera 15 and the authentication processing unit 2, the processing capacity of the CPU 9, and the like, it can also be performed sequentially.

[0100] Regarding the acquisition of the vital sign information B, a region occupied by the skin is extracted from the face 18 detected by an arbitrary skin region extraction algorithm, and the average luminance in the spatial direction is calculated for each of the three channels of R, G, and B from the extracted skin region, and a pulse wave is calculated by acquiring a time series of the luminance signals. Next, the time series of the luminance signals of the three channels acquired are subjected to moving average filtering in the time direction, and the influence of noise is reduced.

[0101] Next, the time series of the luminance signals of the three channels from which noise has been removed by techniques such as ICA (Independent Component Analysis) are decomposed into a plurality of components that are respectively independent. Among the components that constitute the color tone of the image of the face 18 obtained from the front camera 15 that has sensitivity mainly to the wavelength of visible light, there are melanin located in the epidermis layer of the skin, blood vessels located in the dermis layer, adipose tissue located in the subcutaneous tissue, and the like, and by the above-described ICA technique, a blood vessel-dominant luminance component can be acquired. The acquired time series of the blood vessel-dominant luminance component can be provided as the vital sign information B, for example, as a pulse wave of the face 18.

[0102] Next, the authentication terminal 100 acquires biometric authentication information from the dynamic image B acquired from the front camera 15, the vital sign information B (S1035). For example, a feature point indicating the position, shape, and the like of the eyes, nose, mouth, and the like can be extracted from the images of the respective frames constituting the acquired dynamic image B, and the feature point can be used as the biometric authentication information. Alternatively, a feature amount extracted from the face other than the face in the images of the respective frames constituting the dynamic image B using a Deep Learning technique such as FaceNet, ArcFace, BiometricFace, and the like can be used as the biometric authentication information. In addition, information such as the amplitude, period, phase, and the like, and other statistical amounts can be acquired from the extracted vital sign information B as the biometric authentication information.

[0103] Figure 15 is a diagram indicating an example of a case where the dynamic image obtained when the entire lens was shielded with the finger and photographed in the quality determination S104 of the data acquired by the authentication terminal 100 in Embodiment 1.

[0104] Figure 16 is a diagram indicating an example of a case where the dynamic image obtained when only a part of the lens of the back camera 14 was shielded with the finger 17 and photographed in the quality determination S104 (refer to Figure 5 ) of the data acquired by the authentication terminal 100 in Embodiment 1.

[0105] In the acquired information quality determination (S104), it is determined whether the dynamic image, the vital sign information, and the biometric authentication information acquired from the back camera 14 and the front camera 15 are of a quality suitable for performing the impersonation detection and the biometric authentication.

[0106] For example, as shown in Figure 15 , in a case where the finger 17 is photographed in contact with the lens of the back camera 14, if the entire lens is correctly shielded with the finger 17, a dynamic image 28 in which the entire image appears red and greatly flickers over time is obtained from the back camera 14. On the other hand, as shown in Figure 16As shown, when the finger 17 only blocks a part of the lens of the rear camera 14, a small dynamic image 28 in which only a part of the image obtained from the rear camera 14 appears red and flickers over time. In the small dynamic image 28 in which the area occupied by the finger 17 is small, there is a possibility that the background other than the finger is also reflected, and the vital sign information A extracted from the flickering dynamic image 28 carries unnecessary information other than the blood flow of the fingertip, resulting in a decrease in the accuracy of the impersonation detection described later. Therefore, a feature amount related to texture, edge, hue, and the like can also be extracted from the small dynamic image 28 in which flickers, and it can be determined from the tendency of the feature amount whether the reflection of an object including the background other than the finger is present. In the case where the reflection of the object is present, it can also return to the instruction to prompt the posture (S102) and instruct the operator to reposition the finger.

[0107] In addition, as to the vital sign information A and the vital sign information B, the biological authentication information, it can also be determined whether each information can be stably extracted. For example, if the vital sign information A and the vital sign information B are aggregated to be vital sign information, the absolute value of the difference between the vital sign information after noise reduction obtained by performing moving average filtering on the vital sign information in the time direction and the original vital sign information is integrated in the time direction to obtain a value. This value can be considered as the sum of the amount of noise contained in the vital sign information, and if the value is greater than a threshold value decided in advance, the extracted vital sign information is unstable, and the instruction to prompt the posture (S102) is returned, and the photographing can also be performed again on the basis of the appropriate posture guidance.

[0108] For the biological authentication information extracted from each frame of the dynamic image obtained from the photographing section 1 by the rear camera 14, the front camera 15, and the like, the difference degree of the biological authentication information is calculated between different frames. This difference degree indicates how much the biological authentication information changes at each time in the photographing. In the case of prompting the same biological part, it is preferable that the temporal change of the biological authentication information is small, that is, the biological authentication information is stable. Therefore, if the difference degree is greater than a threshold value decided in advance, it can also be considered that the extracted biological authentication information is unstable, and the instruction to prompt the posture (S102) is returned, and the photographing can be performed again on the basis of the appropriate posture guidance.

[0109] In the determination of the presence or absence of impersonation (S105), for example, the following processing can be implemented. First, for the vital sign information A and the vital sign information B that are simultaneously taken from different body parts, respectively, the amplitude, the period, the phase, and the like are calculated, respectively. If these vital sign information are taken from the same person, the period corresponding to the heart rate differs sufficiently small in the vital sign information A and the vital sign information B. That is, in a case where the period is large and not the same, a different person from the person who collected the vital sign information A and the vital sign information B is highly likely to be the person who impersonated the authenticated person of the biometric authentication. In this case, a display on the display 4 or the like is displayed as a registration failure or an authentication failure, and the processing is ended after the operator is notified.

[0110] In addition, after the example of displaying a prompt to press the finger 17 strongly against the rear camera 14 on the display 4 or the text indicating to take the same posture, the finger is photographed again by the rear camera 14, and the vital sign information is obtained from the obtained dynamic image.

[0111] In a case where the finger 17 is photographed by being pressed strongly, the blood circulation of the finger deteriorates, and thus the flicker of the obtained dynamic image becomes weak. By confirming the presence or absence of this phenomenon, it can be confirmed that the finger is prompted as a real object, not a fake finger. Furthermore, the dynamic image is obtained by photographing the finger 17 by the rear camera 14 while the authentication terminal is vibrated by the vibration section 7. In the case of vibration, the object that does not contact the rear camera 14 is vibrated and reflected in the dynamic image, and the object that contacts the rear camera 14 is vibrated in synchronization with the authentication terminal, and thus is not vibrated and reflected in the obtained dynamic image. By confirming the presence or absence of this vibration, it can be confirmed that the finger 17 is prompted by contacting the lens of the rear camera 14, not a fake object that is prompted without contact.

[0112] Embodiment 2

[0113] Figure 17 is a diagram of an example of observing the authentication status from the back side of the authentication terminal of Embodiment 2.

[0114] Figure 18 is a diagram of an example of observing the authentication status from the front side of the authentication terminal of Embodiment 2.

[0115] In this embodiment, the authentication terminal 100 in which the rear camera 14 and the front camera 15 are provided outside the housing 16 and the display 4 is implemented on the basis of confirming that the operator of the terminal is the authentic person of the authenticated person assumed by the authentication terminal 100.

[0116] As shown in Figure 18 , the operator of the terminal photographs the finger 17 by the front camera 15 disposed on the front of the housing 16, as shown in Figure 17As shown, another finger 17 is photographed using a rear camera 14 located on the back of the housing 16. Vital signs information is extracted from the image obtained from the front camera 15, and vital signs information and biometric authentication information are extracted from the image obtained from the rear camera 14. Based on the confirmation that the various vital signs information belong to the same person, biometric authentication is performed based on the biometric authentication information extracted from the finger 17, thereby enabling biometric authentication while preventing impersonation.

[0117] The structure of the authentication terminal 100 in Embodiment 2 is the same as that in Embodiment 1. Furthermore, the registration and authentication processes are largely the same as in Embodiment 1, but the difference lies in the method of extending the finger 17 without contacting the lens to prompt the rear camera 14, instead of prompting the finger 17. Additionally, the prompting method differs in that the finger 17 holding the authentication terminal 100 is brought into contact with the lens without prompting the face to the front camera 15. Therefore, biometric authentication can be implemented even when it is difficult to perform the facial biometric authentication of Embodiment 1 due to differences in factors such as the presence or absence of a mask, glasses, makeup, or hairstyle compared to the registration process.

[0118] like Figure 18 As shown, when photographing finger 17 using the rear camera 14, a hand-shaped guide image 29 representing the approximate shape of the finger and a prompt message 20 instructing the user to photograph finger 17 can also be displayed on the display 4. This is because, for a face that can be naturally photographed using the front camera 15, which is on the same side as the display 4, when looking at the display 4, a prompting posture is needed to guide the user in order to photograph the finger effectively using the rear camera 14, which is located on the back. Moreover, the hand-shaped guide image 29 displayed on the display 4 can only magnify the area of ​​the finger 17. Thus, compared to photographing the entire finger 17 using the rear camera 14, the area of ​​the finger can be photographed at a higher resolution, which can be expected to improve the authentication accuracy when using small spatial patterns such as folds on the finger surface and blood vessels near the finger surface as biometric authentication information.

[0119] In addition, when taking a picture of the finger 17 with the front-facing camera 15, the illumination of the display 4 can be temporarily increased for the purpose of taking the picture. As a result, the light emitted from the display 4 passes through the finger 17 and is scattered. By using the front-facing camera 15 to capture this situation, the visual recognition of blood vessels in the dynamic image is improved, and vital signs information such as pulse wave and heart rate can be obtained with high precision.

[0120] Example 3

[0121] Figure 19 This is a diagram illustrating an example of observing the authentication status from the back side of the authentication terminal in Embodiment 3.

[0122] Figure 20 FIG. 3 is a diagram showing an example of observing the authentication state from the front side of the authentication terminal of Embodiment 3.

[0123] In Embodiment 3, the authentication terminal 100 provided with the rear camera 14 and the front camera 15 on the outside of the housing 16, the display 4, on the basis of confirming that the operator of the terminal is the authenticator himself / herself assumed by the biometric authentication system, implements biometric authentication. The operator of the terminal photographs the face 18 by the front camera 15, and photographs the finger 17 by the rear camera 14. From the image obtained by the front camera 15, vital sign information and biometric authentication information are extracted, and from the image obtained by the rear camera 14, vital sign information and biometric authentication information are extracted. On the basis of confirming that each vital sign information comes from the same person, biometric authentication is implemented on the basis of the biometric authentication information extracted from the face 18 and the finger 17, whereby the impersonation by another person can be prevented and biometric authentication can be implemented.

[0124] The structure of the authentication terminal 100 in Embodiment 3 is the same as that in Embodiment 1. Also, the processing flow at the time of registration and at the time of authentication has many commonalities with Embodiment 1, but the difference is that the finger is not prompted to the rear camera 14 by making contact with the lens, but is prompted in the form of not making contact and extending. Also, the difference is that from the biological part prompted to the rear camera 14, not only vital sign information but also biometric authentication information is extracted. Thereby, by combining the biometric authentication information extracted from the face 18 and the finger 17, biometric authentication is implemented, and compared with the case of implementing biometric authentication with the face 18 alone or the finger 17 alone, the authentication can be performed with high accuracy.

[0125] When biometric authentication information extracted from the face 18 and the finger 17 is combined to implement registration and authentication processing, it can also be combined with the face photograph recorded in a public identification document such as a driver's license, a national ID card, and the like. For example, when biometric authentication information is registered to a certain system, in order to confirm whether the person having personal information such as name, date of birth, address, and the like input to the system and the person inputting are the same person, a comparison of the personal information input to the system and the personal information recorded in the public identification document, a comparison of the face of the person photographed by the camera activated at the time of registration to the system and the face photograph recorded in the public identification document are implemented, whereby the registration information of the system and the information of the face of the person can be associated and registered. At this time, if other biological parts such as a finger are also photographed at the same time, and on the basis of the vital sign information obtained, it can be confirmed that the biological part and the face are the same person, the information of the biological part other than the face can also be associated with the registration information of the system. Thereby, for example, at the time of logging in to the system and the like, biometric authentication of the biological part other than the face can be implemented, and the convenience can be improved.

[0126] In addition, in a case where the face 18 and the finger 17 are photographed at the same time, for example, the image 22 that reflects the face 18 photographed by the front camera 15 during photographing and the image 30 that reflects the finger 17 photographed by the rear camera can be displayed on the display 4. At this time, in a case where the finger 17 that is prompted by the gesture guide image 29 to the rear camera 14 is difficult to be prompted as compared with the face 18 that can be naturally photographed based on the front camera 15 by visually displaying the display 4, the image 30 that reflects the finger 17 is displayed larger on the display 4 than the image 22 that reflects the face 18, whereby the prompting based on the finger 17 of the operator can be made easier.

[0127] Embodiment 4

[0128] Figure 21 is a diagram that indicates an example of the authentication state of Embodiment 4.

[0129] In Embodiment 4, unlike the first and second and third embodiments, the photographing section 1 is constituted by one front camera 15. In this case, the vital sign information A is extracted from a dynamic image obtained by photographing one living body part, for example, the finger 17 that contacts the lens of the front camera 15. Thereafter, the vital sign information B and the biometric authentication information are extracted from a dynamic image obtained by photographing the other living body part, for example, the face 18. The identity of the vital sign information A obtained by the method that is difficult to be prompted by the operator other than the vital sign information B is confirmed, and the biometric authentication is performed based on the biometric authentication information extracted from the dynamic image from which the vital sign information B is derived. Thus, in a case where the photographing section 1 is constituted by one camera, the operator can be authenticated by the biometric authentication while preventing impersonation by another person.

[0130] In addition, the present application is not limited to the above-described embodiments, and various modifications are included. For example, the above-described embodiments are described in detail for better understanding of the present application, and are not limited to necessarily having all the structures described.

[0131] In addition, part or all of each structure, function, processing section, processing unit, and the like described above can be implemented by hardware, for example, by designing in an integrated circuit. In addition, each structure, function, and the like described above can be implemented by software by a processor interpreting and executing a program that implements each function. The program, table, file, and the like that implement each function can be stored in a nonvolatile semiconductor memory, a hard disk drive, an SSD (Solid State Drive), or the like, a storage device, or an IC card, an SD card, a DVD, or the like, a non-transitory data storage medium that is readable by a computer.

[0132] In addition, control lines and information lines are shown as necessary for explanation, and all control lines and information lines on the product are not necessarily shown. It can also be considered that almost all structures are connected to each other.

[0133] Symbol explanation

[0134] 1 photographing section

[0135] 2 authentication processing section

[0136] 3 storage section

[0137] 4 display section

[0138] 5 input section

[0139] 6 posture detection section

[0140] 7 vibration section

[0141] 8 sound output section

[0142] 9 CPU

[0143] 10 memory

[0144] 11 IF

[0145] 12 authentication section

[0146] 13 authentication section

[0147] 14 rear camera

[0148] 15 front camera

[0149] 16 housing

[0150] 17 finger

[0151] 18 face

[0152] 19 image showing the operation method of the biometric authentication system

[0153] 20 message

[0154] 21 displayed vital sign information

[0155] 22 image photographed by the front camera

[0156] 23 extracted vital sign information

[0157] 24 signal component of the extracted vital sign information

[0158] 25 noise component of the extracted vital sign information

[0159] 26 pseudo vital sign information

[0160] 27 pseudo vital sign information to which the noise component is added

[0161] 28 a moving image of the finger in contact with the lens

[0162] 29 a gesture guide image

[0163] 30 an image taken by the rear camera

Claims

1. A biometric authentication system, characterized in that, have: The imaging unit acquires first and second image data from different biological regions of the imaging operator within a predetermined period. The display unit guides the operator to position the displayed biological regions in order to capture different biological regions of the operator; The storage unit pre-stores the operator's biometric authentication information; as well as The authentication processing unit extracts first vital sign information and second vital sign information from the first image data and the second image data of the different biological regions, respectively. Based on the first vital sign information and the second vital sign information, it determines the identity of the operator. If the identity of the operator is confirmed, it extracts the operator's biometric authentication information from the second image data and performs biometric authentication based on the extracted biometric authentication information and the biometric authentication information stored in the storage unit. The extracted biometric authentication information is temporarily stored as registration candidate data; the authentication processing unit calculates the difference between the registration candidate data; if the difference exceeds a preset registration threshold, registration fails; if the difference is lower than the preset registration threshold, registration succeeds and the registration candidate data is stored in the storage unit. The biological area captured by the rear camera of the imaging unit is the operator's finger. The authentication processing unit determines that the operator's finger is in contact with the imaging unit; The imaging unit has a vibrating part that causes vibration. The imaging unit captures images of a finger while the vibrating unit is vibrating, thereby obtaining a dynamic image.

2. The biometric authentication system according to claim 1, characterized in that, The first image data and the second image data are acquired by the imaging unit at the same timing.

3. The biometric authentication system according to claim 2, characterized in that, The first vital sign information and the second vital sign information are pulse waves obtained simultaneously by the imaging unit from different biological regions of the operator.

4. An authentication terminal, characterized in that, have: The imaging unit consists of a rear camera located on the back of the housing and a front camera located on the front of the housing. It acquires first image data and second image data by capturing images of different biological regions of the operator during a predetermined period. The display unit, in order to capture images of different biological regions of the operator, displays positional guidance of the biological regions to the operator; The storage unit pre-stores the operator's biometric authentication information; as well as The authentication processing unit extracts first vital sign information and second vital sign information from the first image data and the second image data of the different biological regions, respectively. Based on the first vital sign information and the second vital sign information, it determines the identity of the operator. If the identity of the operator is confirmed, it extracts the operator's biometric authentication information from the second image data and performs biometric authentication based on the extracted biometric authentication information and the biometric authentication information stored in the storage unit. The extracted biometric authentication information is temporarily stored as registration candidate data; the authentication processing unit calculates the difference between the registration candidate data; if the difference exceeds a preset registration threshold, registration fails; if the difference is lower than the preset registration threshold, registration succeeds and the registration candidate data is stored in the storage unit. The biological area captured by the rear camera of the imaging unit is the operator's finger. The authentication processing unit determines that the operator's finger is in contact with the imaging unit; The imaging unit has a vibrating part that causes vibration. The imaging unit captures images of a finger while the vibrating unit is vibrating, thereby obtaining a dynamic image.

5. The authentication terminal according to claim 4, characterized in that, The first vital signs information and the second vital signs information are acquired simultaneously by the imaging unit.

6. The authentication terminal according to claim 4, characterized in that, The authentication terminal has a posture detection unit that detects changes in the posture of the authentication terminal. The display unit changes its display content based on the posture information obtained by the posture detection unit.

7. The authentication terminal according to claim 4, characterized in that, The display unit shows a position guide when the finger is pressed on the shooting unit.

8. The authentication terminal according to claim 4, characterized in that, The biological area captured by the front-facing camera includes the area containing the operator's face.

9. An authentication method, characterized in that, The imaging unit acquires first and second image data by photographing different biological regions of the operator within a predetermined period. In the display unit, guidelines are displayed to guide the operator in positioning different biological regions in order to capture images of those regions. The operator's biometric authentication information is pre-stored in the storage unit. The authentication processing unit extracts first vital sign information and second vital sign information from the first image data and the second image data of the different biological regions, respectively. Based on the first vital sign information and the second vital sign information, the identity of the operator is determined. If the identity of the operator is confirmed, the biometric authentication information of the operator is extracted from the second image data. Biometric authentication is performed based on the extracted biometric authentication information and the biometric authentication information stored in the storage unit. The extracted biometric authentication information is temporarily stored as registration candidate data; the authentication processing unit calculates the difference between the registration candidate data; if the difference exceeds a preset registration threshold, registration fails; if the difference is lower than the preset registration threshold, registration succeeds and the registration candidate data is stored in the storage unit. The biological area captured by the rear camera of the imaging unit is the operator's finger. The authentication processing unit determines that the operator's finger is in contact with the imaging unit; The imaging unit has a vibrating part that causes vibration. The imaging unit captures images of a finger while the vibrating unit is vibrating, thereby obtaining a dynamic image.

Images