Ultrasonic imaging device and method

Abstract

The present application relates to ultrasonic imaging devices and methods. A device may include an ultrasonic sensor array and a control system. The control system may be configured to acquire first image data generated by the ultrasonic sensor array corresponding to at least one first reflected ultrasonic wave received by at least a portion of the ultrasonic sensor array from a target object during a first acquisition time window. The control system may be configured to acquire second image data generated by the ultrasonic sensor array corresponding to at least one second reflected ultrasonic wave received by at least a portion of the ultrasonic sensor array from the target object during a second acquisition time window longer than the first acquisition time window. The control system may further be configured to initiate an authentication process based on the first image data and the second image data.

Description

[0001] Information about divisional applications

[0002] This application is a divisional application. The parent application is an invention patent application filed on September 23, 2016, with application number 201680055520.X and the title of invention being “Ultrasonic Imaging Device and Method.”

[0003] Priority claim

[0004] This application is a continuation-in-part of and claims priority to U.S. patent application Ser. No. 15 / 253,387, filed on August 31, 2016, entitled “Ultrasonic Imaging Apparatus and Method,” which in turn claims priority to U.S. Provisional Patent Application Ser. No. 62 / 233,335, filed on September 26, 2015, entitled “Methods and Systems for Detecting Fraud,” and U.S. Provisional Patent Application Ser. No. 62 / 363,067, filed on July 15, 2016, entitled “Fraud and Liveness Detection by Ultrasonic Imaging,” all of which are incorporated herein by reference. Technical Field

[0005] The present invention generally relates to biometric identification devices and methods, including but not limited to ultrasonic sensor systems and methods using such systems. Background Art

[0006] Technologically savvy hackers revel in defeating the latest technological security innovations. For example, a premium phone manufacturer successfully compromised its first smartphone, which incorporated a fingerprint-based authentication system, shortly after its launch. In some examples, spoofing can involve using a finger-shaped object made of silicone rubber, polyvinyl acetate (PVC), gelatin, glycerin, or the like, with a legitimate user's fingerprint pattern formed on the outer surface. In some cases, the hacker can form the legitimate user's fingerprint pattern on a sleeve or portion of the sleeve, which can then be slid over or on the hacker's finger. Summary of the Invention

[0007] The systems, methods, and devices of the disclosure each have several innovative aspects, no single one of which is solely responsible for the desirable attributes disclosed herein.

[0008] One innovative aspect of the subject matter described herein can be implemented in an apparatus. The apparatus can include an ultrasonic sensor array and a control system configured to communicate with the ultrasonic sensor array. In some examples, at least a portion of the control system can be coupled to the ultrasonic sensor array. In some embodiments, a mobile device can be or include the apparatus. For example, the mobile device can include the apparatus disclosed herein.

[0009] The control system may include one or more general-purpose single-chip or multi-chip processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or a combination thereof. According to some examples, the control system may be configured to acquire first image data generated by the ultrasonic sensor array. The first image data may correspond to at least one first reflected ultrasonic wave received from the target object by at least a portion of the ultrasonic sensor array during a first acquisition time window. In some embodiments, the control system may be configured to acquire second image data generated by the ultrasonic sensor array. In some examples, the second image data may correspond to at least one second reflected ultrasonic wave received from the target object by at least a portion of the ultrasonic sensor array during a second acquisition time window that is longer than the first acquisition time window. According to some examples, the control system may be configured to initiate an authentication process based on the first image data and the second image data.

[0010] According to some examples, the first acquisition time window may begin at the end time of the first acquisition time delay. In some instances, the second acquisition time window may begin at the end time of the second acquisition time delay. In some examples, the first acquisition time delay and the first acquisition time window may cause the first image data to correspond to a fingerprint feature of the target object. In some such examples, the second acquisition time delay and the second acquisition time window may cause the second image data to correspond to a subcutaneous feature of the target object. In some embodiments, the first acquisition time delay and the second acquisition time delay may have equal durations. In some examples, the device may include a pressure plate positioned relative to the ultrasonic sensor array. According to some embodiments, the first acquisition time delay or the second acquisition time delay may correspond to an estimated amount of time for ultrasonic waves reflected from the pressure plate surface to be received by the ultrasonic sensor array. According to some examples, the first acquisition time delay and the first acquisition time window may cause the first image data to correspond to a fingerprint feature of the target object. For example, the second acquisition time delay and the second acquisition time window may cause the second image data to correspond to both the fingerprint feature of the target object and the subcutaneous feature of the target object.

[0011] In some examples, the target object can be a finger of an individual, such as a user's finger. According to some embodiments, the first image data can include at least one fingerprint feature of the user's finger and the second image data can include at least one subcutaneous feature of the user's finger. In some embodiments, the first image data and the second image data can be acquired using a receiver bias control signal or a diode bias control signal.

[0012] According to some examples, the control system can be further configured to collect third image data generated by the ultrasonic sensor array. The third image data can, for example, correspond to at least one third reflected ultrasonic wave received by the ultrasonic sensor array from the target object. In some examples, the initiation of the authentication process can be based on a time-based feature difference between the third image data and the first image data or the second image data. According to some embodiments, an activity indicator can be generated based on the time-based feature difference.

[0013] In some embodiments, the authentication process may include detecting one or more surface fingerprint features on the surface of the target object and one or more subsurface fingerprint features below the surface of the target object. According to some embodiments, the initial authentication process may include generating an indication of detected spoofing based on a difference between the surface fingerprint features and the subsurface fingerprint features.

[0014] In some instances, as part of an initial authentication process, a fingerprint feature on the surface of a target object may be identified based on a registered fingerprint template. According to some instances, a plurality of image data may be collected in a subsurface area of ​​the target object based on the identified fingerprint feature. In some such instances, the initial authentication process may be further based on a plurality of image data collected in a subsurface area of ​​the target object based on the identified fingerprint feature. In some embodiments, the plurality of image data may be generated by at least a portion of an ultrasonic sensor array. According to some instances, a candidate user may be verified based at least in part on the presence or absence of temporal changes in the plurality of image data collected in the subsurface area.

[0015] Yet other innovative aspects of the subject matter described herein can be implemented in an authentication method. The method may include acquiring first image data generated by an ultrasonic sensor array. The first image data may, for example, correspond to at least one first reflected ultrasonic wave received from a target object by at least a portion of the ultrasonic sensor array during a first acquisition time window. The method may include acquiring second image data generated by the ultrasonic sensor array. The second image data may, for example, correspond to at least one second reflected ultrasonic wave received from the target object by at least a portion of the ultrasonic sensor array during a second acquisition time window that is longer than the first acquisition time window. In some examples, the method may include initiating an authentication process based on the first image data and the second image data.

[0016] In some examples, the first acquisition time window may begin at the end time of the first acquisition time delay and the second acquisition time window may begin at the end time of the second acquisition time delay. According to some embodiments, the first acquisition time delay or the second acquisition time delay may correspond to an estimated amount of time for ultrasound waves to reflect from the platen surface and be received by at least a portion of the ultrasonic sensor array. In some embodiments, the first acquisition time delay and the first acquisition time window may cause the first image data to correspond to fingerprint features of the target object. In some such embodiments, the second acquisition time delay and the second acquisition time window may cause the second image data to correspond to fingerprint features of the target object and to subcutaneous features of the target object. In some examples, the first acquisition time delay and the second acquisition time delay may be of equal duration.

[0017] One or more devices may perform some or all of the operations, functions, and / or methods described herein according to instructions (e.g., software) stored on non-transitory media. Such non-transitory media may include memory devices such as those described herein, including but not limited to random access memory (RAM) devices, read-only memory (ROM) devices, and the like. Thus, some innovative aspects of the subject matter described in this disclosure may be implemented in non-transitory media having software stored thereon.

[0018] For example, the software may include instructions for controlling one or more devices to perform an authentication method. In some instances, the method may include acquiring first image data generated by an ultrasonic sensor array. The first image data may, for example, correspond to at least one first reflected ultrasonic wave received from a target object by at least a portion of the ultrasonic sensor array during a first acquisition time window. The method may include acquiring second image data generated by the ultrasonic sensor array. The second image data may, for example, correspond to at least one second reflected ultrasonic wave received from a target object by at least a portion of the ultrasonic sensor array during a second acquisition time window that is longer than the first acquisition time window. In some instances, the method may include initiating an authentication process based at least in part on the first image data and the second image data.

[0019] In some examples, the first acquisition time window may begin at the end time of the first acquisition time delay and the second acquisition time window may begin at the end time of the second acquisition time delay. According to some embodiments, the first acquisition time delay or the second acquisition time delay may correspond to an estimated amount of time for ultrasound waves to reflect from the platen surface and be received by at least a portion of the ultrasonic sensor array. In some embodiments, the first acquisition time delay and the first acquisition time window may cause the first image data to correspond to fingerprint features of the target object. In some such embodiments, the second acquisition time delay and the second acquisition time window may cause the second image data to correspond to fingerprint features of the target object and to subcutaneous features of the target object. In some examples, the first acquisition time delay and the second acquisition time delay may be of equal duration.

[0020] Other innovative aspects of the subject matter described herein can be implemented in an apparatus. The apparatus can include an ultrasonic sensor array and a control system configured to communicate with the ultrasonic sensor array. In some examples, at least a portion of the control system can be coupled to the ultrasonic sensor array. In some embodiments, a mobile device can be or include the apparatus. For example, the mobile device can include the apparatus disclosed herein.

[0021] The control system may include one or more general-purpose single-chip or multi-chip processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or a combination thereof. According to some examples, the control system may be configured to control the ultrasonic sensor array to acquire ultrasonic image data corresponding to at least one reflected ultrasonic wave received by at least a portion of the ultrasonic sensor array from the target object during an acquisition time window. In some examples, the control system may be configured to extract first fingerprint data from the ultrasonic image data. According to some examples, the control system may be configured to determine whether the ultrasonic image data includes second fingerprint data having a depth different from the first fingerprint data and, if it is determined that the ultrasonic image data does not include the second fingerprint data different from the first fingerprint data, perform an authentication process based at least in part on the first fingerprint data.

[0022] In some embodiments, the control system can be further configured to determine a subcutaneous feature from the ultrasound image data. In some instances, the authentication process can be based at least in part on the subcutaneous feature. According to some embodiments, the control system can be further configured to obtain a first subcutaneous feature from the ultrasound image data at a first time, obtain a second subcutaneous feature from the second ultrasound image data at a second time, and perform an activity determination based on a change between the first subcutaneous feature and the second subcutaneous feature.

[0023] Yet other innovative aspects of the subject matter described herein can be implemented in an authentication method. The method may include controlling an ultrasonic sensor array to acquire ultrasonic image data corresponding to at least one reflected ultrasonic wave received by at least a portion of the ultrasonic sensor array from a target object during an acquisition time window. In some examples, the method may include extracting first fingerprint data from the ultrasonic image data, determining whether the ultrasonic image data includes second fingerprint data having a depth different from the first fingerprint data, and, if it is determined that the ultrasonic image data does not include the second fingerprint data different from the first fingerprint data, performing an authentication process based at least in part on the first fingerprint data.

[0024] In some examples, the method may include determining subcutaneous features from the ultrasound image data. In some such examples, the authentication process may be based at least in part on the subcutaneous features.

[0025] According to some embodiments, the method may include acquiring a first subcutaneous feature from first ultrasound image data at a first time, acquiring a second subcutaneous feature from second ultrasound image data at a second time, and determining activity based on changes between the first subcutaneous feature and the second subcutaneous feature.

[0026] Still other innovative aspects of the subject matter described in this disclosure may be implemented in a non-transitory medium having software stored thereon. For example, the software may include instructions for controlling one or more devices to perform an authentication method. In some instances, the method may include controlling an ultrasonic sensor array to acquire ultrasonic image data corresponding to at least one reflected ultrasonic wave received by at least a portion of the ultrasonic sensor array from a target object during an acquisition time window. In some instances, the method may include extracting first fingerprint data from the ultrasonic image data, determining whether the ultrasonic image data includes second fingerprint data having a depth different from the first fingerprint data, and, if it is determined that the ultrasonic image data does not include second fingerprint data different from the first fingerprint data, performing an authentication process based at least in part on the first fingerprint data.

[0027] In some examples, the method may include determining subcutaneous features from the ultrasound image data. In some such examples, the authentication process may be based at least in part on the subcutaneous features.

[0028] According to some embodiments, the method may include acquiring a first subcutaneous feature from first ultrasound image data at a first time, acquiring a second subcutaneous feature from second ultrasound image data at a second time, and determining activity based on changes between the first subcutaneous feature and the second subcutaneous feature. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Details of one or more embodiments of the subject matter described in this specification are set forth in the accompanying drawings and the following description. Additional features, aspects, and advantages will become apparent from the description, drawings, and appended claims. It should be noted that the relative dimensions of the following figures may not be drawn to scale. Like reference numerals and names in the various figures indicate like elements.

[0030] Figure 1A Examples of subepidermal features are shown.

[0031] Figure 1B is a block diagram illustrating example components of an apparatus according to some disclosed implementations.

[0032] Figure 1C A flowchart providing an example of the operation of a biometric system.

[0033] Figure 1D Some examples of acquisition time delays and acquisition time windows are shown.

[0034] Figures 2A to 2C Examples of A-scan, B-scan, and C-scan images are shown.

[0035] Figure 2D An example of a cross-sectional view of an apparatus capable of performing at least some of the methods described herein is shown.

[0036] Figure 2E An example of a mobile device including the biometric recognition system disclosed herein is shown.

[0037] Figure 3A Is a flowchart containing blocks for alternative methods.

[0038] Figure 3B Some alternative examples of acquisition time delays and acquisition time windows are shown.

[0039] Figure 4 Shows an example of a fingerprint image superimposed on multiple subepidermal features.

[0040] Figure 5 An example of overlapping fingerprint images is shown.

[0041] Figures 6A to 6C is a graph showing an example of the time difference between two A-scan reflections.

[0042] Figure 7 An example of the registration and matching process using fingerprints and bone structure is shown.

[0043] Figure 8A and 8B An example of the registration and matching process using fingerprints and bone structure is shown.

[0044] Figure 9 An example of an enrollment and matching process for detecting slipover fingerprint spoofing, such as slipover spoofing, is shown.

[0045] Figure 10A and 10B An example of the registration and matching process with fingerprints and pore / follicle locations is shown.

[0046] Figure 11A and 11B An example of the registration and matching process with depth distribution and time variation is shown.

[0047] Figure 12 An example of a 3D image of a fingerprint is shown.

[0048] Figure 13 An example of multiple acquisition time delays selected to receive acoustic waves reflected from different depths is shown.

[0049] Figure 14 Representatively depicted are aspects of a 4x4 pixel array of sensor pixels for an ultrasonic sensor system.

[0050] Figure 15A and 15B An example arrangement of ultrasonic transmitters and receivers in an ultrasonic sensor system is shown, but other arrangements are possible. DETAILED DESCRIPTION

[0051] The following description relates to certain embodiments for the purpose of describing the innovative aspects of the present invention. However, those skilled in the art will readily recognize that the teachings herein may be applied in many different ways. The described embodiments may be implemented in any device, apparatus, or system that includes the biometric identification system disclosed herein. In addition, it is contemplated that the described embodiments may be included in or associated with a wide variety of electronic devices, such as, but not limited to: mobile phones, cellular phones with multimedia Internet capabilities, mobile television receivers, wireless devices, smartphones, smart cards, wearable devices (e.g., bracelets, armbands, wristbands, rings, headbands, patches, etc.), Devices include personal data assistants (PDAs), wireless email receivers, handheld or portable computers, netbooks, notebook computers, smart computers, tablet computers, printers, copiers, scanners, fax devices, global positioning system (GPS) receivers / navigators, cameras, digital media players (such as MP3 players), camcorders, game consoles, watches, clocks, calculators, television monitors, flat panel displays, electronic reading devices (such as e-card readers), mobile health devices, computer monitors, automotive displays (including odometer and speedometer displays, etc.), cockpit controls and / or displays, camera view displays (such as the display of a rearview camera in a vehicle), electronic photographs, electronic billboards or signs, projectors, architectural structures, microwaves, refrigerators, stereo systems, cassette recorders or players, DVD players, CD players, VCRs, radios, portable memory chips, washers, dryers, washer / dryers, parking meters, packaging (e.g., in electromechanical systems (EMS) applications including microelectromechanical systems (MEMS) applications as well as non-EMS applications), aesthetic structures (e.g., the display of an image on a piece of jewelry or clothing), and various EMS devices. The teachings herein may also be used in applications such as, but not limited to, electronic switching devices, radio frequency filters, sensors, accelerometers, gyroscopes, motion sensing devices, magnetometers, inertial components for consumer electronic devices, components for consumer electronic device products, steering wheels or other automotive components, varactor diodes, liquid crystal devices, electrophoretic devices, drive schemes, manufacturing processes, and electronic test equipment. Thus, the teachings are not intended to be limited to the embodiments depicted in the figures, but instead have broad applicability, as will be readily apparent to those skilled in the art.

[0052] Some embodiments may include an ultrasonic sensor system capable of acquiring image data from the epidermis (eg, fingerprint image data) and image data corresponding to sub-epidermal features. Figure 1A As used herein, the term "subcutaneous features" may refer to any of the tissue layers below the epidermis 100 (including the dermis, papillary layer, reticular layer, subcutaneous tissue, etc.) and any blood vessels, lymphatic vessels, sweat glands, hair follicles, hair papillae, lipid lobules, etc. that may be present in such tissue layers. Figure 1A Features not shown in the figure, such as muscle tissue, bone material, etc.

[0053] Some embodiments may be capable of performing enrollment and authentication processes based at least in part on subsurface features. Some such processes may also be based on fingerprint image data, or on fingerprint minutiae or fingerprint image features, such as key points derived from fingerprint image data. The authentication process may include spoofing detection and / or liveness detection.

[0054] In some examples, the user authentication process can include comparing "attribute information" obtained from received image data based on signals from the ultrasonic sensor array with stored attribute information obtained from image data previously received from an authorized user during a registration procedure. According to some such examples, the attribute information can include information about subepidermal features, such as information about dermal features, subcutaneous tissue features, vascular features, lymphatic vascular features, sweat gland features, hair follicle features, hair papilla features, and / or lipid lobules, as well as minutiae or key point information associated with a registered fingerprint.

[0055] Alternatively or additionally, in some embodiments, the attribute information obtained from the received image data and the stored attribute information may include information regarding skeletal tissue characteristics, muscle tissue characteristics, and / or epidermal or subepidermal tissue characteristics. For example, according to some embodiments, a user authentication process may include acquiring fingerprint image data and subepidermal image data. In such instances, the authentication process may include evaluating the attribute information obtained from the fingerprint image data.

[0056] The attribute information derived from the received image data and the stored attribute information compared during the authentication process may include biometric template data corresponding to the received image data and a biometric template corresponding to the stored image data. One known type of biometric template data is fingerprint template data, which may indicate the type and location of fingerprint minutiae or key points. A user authentication process based on attributes of fingerprint image data may include comparing the received and stored fingerprint template data. This process may or may not include directly comparing the received and stored fingerprint image data.

[0057] Similarly, the biometric template data corresponding to the subepidermal features may include information about blood vessel attributes, such as information about blood vessel type and location characteristics, such as blood vessel size, blood vessel direction, blood vessel branch point location, etc. Alternatively or in addition, the biometric template data corresponding to the subepidermal features may include attribute information about the type (e.g., size, shape, direction, etc.) and location of dermal features, subcutaneous tissue features, lymphatic vessel features, sweat gland features, hair follicle features, hair papilla features, lipid lobules features, muscle tissue, and / or bone material.

[0058] Particular embodiments of the subject matter described in this disclosure may be implemented to realize one or more of the following potential advantages. As mentioned above, some spoofing techniques are based on forming fingerprint-like features on an object, which may be a finger-like object. However, manufacturing a finger-like object with detailed subcutaneous features, muscle tissue features, and / or bone tissue features would be challenging and expensive. Manufacturing features that precisely correspond to those of an authorized user would be even more challenging. Enabling such features to move in a human-like, biomimetic manner or in a manner that replicates a legitimate user would raise the barrier to spoofing even higher. Because some disclosed embodiments include obtaining attribute information based at least in part on subcutaneous features, some such embodiments may provide more reliable authentication. Some such embodiments may be able to provide a determination of "liveness."

[0059] Figure 1B is a block diagram illustrating example components of an apparatus according to some disclosed implementations. In this embodiment, apparatus 101 includes an ultrasonic sensor array 102 and a control system 106. Although Figure 1B Although not shown, device 101 can include a substrate. Some examples are described below. Some embodiments of device 101 can include interface system 104. In some examples, device 101 can include ultrasonic transmitter 108.

[0060] Various examples of ultrasonic sensor arrays 102 are disclosed herein, some of which may include individual ultrasonic transmitters and some of which may not. Figure 1BAlthough shown as separate elements in FIG. , in some embodiments, the ultrasonic sensor array 102 and ultrasonic transmitter 108 can be combined into an ultrasonic transceiver. For example, in some embodiments, the ultrasonic sensor array 102 can include a piezoelectric receiver layer, such as a polyvinylidene fluoride (PVDF) polymer layer or a polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) copolymer layer. In some embodiments, a separate piezoelectric layer can function as an ultrasonic transmitter. In some embodiments, a single piezoelectric layer can function as both a transmitter and a receiver. In some embodiments, other piezoelectric materials can be used in the piezoelectric layer, such as aluminum nitride (AlN) or lead zirconate titanate (PZT). In some examples, the ultrasonic sensor array 102 can include an array of ultrasonic transducer elements, such as a piezoelectric micromachined ultrasonic transducer (PMUT) array, a capacitive micromachined ultrasonic transducer (CMUT) array, and the like. In some such examples, the piezoelectric receiver layer, the PMUT elements in a single-layer PMUT array, or the CMUT elements in a single-layer CMUT array can function as both an ultrasonic transmitter and an ultrasonic receiver. According to some alternative examples, the ultrasonic sensor array 102 can be an array of ultrasonic receivers and the ultrasonic transmitter 108 can include one or more individual elements. In some such examples, the ultrasonic transmitter 108 can include an ultrasonic plane wave generator, such as those described below.

[0061] The control system 106 may include one or more general purpose single-chip or multi-chip processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or a combination thereof. The control system 106 may also include one or more memory devices (e.g., one or more random access memory (RAM) devices, read-only memory (ROM) devices, etc.) and / or may be configured to communicate with the one or more memory devices. Thus, the apparatus 101 may have a memory system that includes one or more memory devices, but the memory system may be configured to communicate with the one or more memory devices. Figure 1B 1. The control system 106 may be capable of receiving and processing data from the ultrasonic sensor array 102, e.g., as described below. If the device 101 includes an ultrasonic transmitter 108, the control system 106 may be capable of controlling the ultrasonic transmitter 108, e.g., as disclosed elsewhere herein. In some embodiments, the functionality of the control system 106 may be distributed between one or more controllers or processors (e.g., a dedicated sensor controller) and an application processor of the mobile device.

[0062] Some embodiments of the device 101 may include an interface system 104. In some examples, the interface system may include a wireless interface system. In some embodiments, the interface system may include a user interface system, one or more network interfaces, one or more interfaces between the control system 106 and a memory system, and / or one or more interfaces between the control system 106 and one or more external device interfaces (e.g., a port or application processor).

[0063] Interface system 104 can be configured to provide communication between components of device 101 (which can include wired or wireless communication, such as electrical communication, radio communication, etc.). In some such examples, interface system 104 can be configured to provide communication between control system 106 and ultrasonic sensor array 102. According to some such examples, a portion of interface system 104 can couple at least a portion of control system 106 to ultrasonic sensor array 102, for example, via a conductive material. If device 101 includes ultrasonic transmitter 108 separate from ultrasonic sensor array 102, interface system 104 can be configured to provide communication between at least a portion of control system 106 and ultrasonic transmitter 108. According to some examples, interface system 104 can be configured to provide communication between the system and other devices and / or humans. In some such examples, interface system 104 can include one or more user interfaces. In some examples, interface system 104 can include one or more network interfaces and / or one or more external device interfaces (e.g., one or more Universal Serial Bus (USB) interfaces). In some embodiments, device 101 can include a memory system. In some examples, interface system 104 may include at least one interface between control system 106 and a memory system.

[0064] Device 101 can be used in a variety of different contexts, and multiple examples of such devices are disclosed herein. For example, in some embodiments, a mobile device can include at least a portion of device 101. In some embodiments, a wearable device can include at least a portion of device 101. The wearable device can be, for example, a bracelet, armband, wristband, ring, headband, or patch. In some embodiments, control system 106 can reside in more than one device. For example, a portion of control system 106 can reside in a wearable device and another portion of control system 106 can reside in another device, such as a mobile device (e.g., a smartphone or tablet computer). In some such examples, interface system 104 can also reside in more than one device.

[0065] Figure 1C A flowchart providing an example of the operation of a biometric system. Figure 1C The blocks of (and blocks of other flowcharts provided herein) may be, for example, Figure 1BThe device 101 or similar device is executed. As with other methods disclosed herein, Figure 1C The methods outlined in the foregoing may include more or fewer blocks than indicated. Furthermore, the method blocks disclosed herein are not necessarily executed in the order indicated.

[0066] In this embodiment, block 103 includes collecting data from an array of ultrasonic sensors (e.g. Figure 1B In some instances, the first image data may be received from the ultrasonic sensor array, while in other instances, the first image data may be received from a memory device (e.g., a buffer). In this example, the first image data corresponds to at least one first reflected ultrasonic wave received from a target object by at least a portion of the ultrasonic sensor array during a first acquisition time window. In some instances, the target object may be a finger of an individual, such as a user's finger. However, in other instances, the target object may be an artificial finger-like object, which may be referred to as a "fake finger." The data received from the ultrasonic sensor array may be referred to herein as "image data," but the image data will typically be received in the form of electrical signals. Therefore, without additional processing, such image data will not necessarily be perceived by humans as an image.

[0067] According to this embodiment, block 105 includes acquiring second image data generated by the ultrasonic sensor array. In this example, the second image data corresponds to at least one second reflected ultrasonic wave received from at least the portion of the target object by at least a portion of the ultrasonic sensor array during a second acquisition time window that is longer than the first acquisition time window. According to some embodiments, the first image data may include at least one fingerprint feature of the target object, and the second image data may include at least one subcutaneous feature of the target object. In some embodiments, the first image data and the second image data may be acquired using a receiver bias control signal or a diode bias control signal. Some examples are described below.

[0068] According to this example, block 107 includes initiating an authentication process based on the first image data and the second image data. Various examples of authentication processes are disclosed herein. In some examples, the authentication process can verify a legitimate user. In some such examples, the target object can be a finger of the legitimate user.

[0069] According to some examples, the control system may be further configured to acquire third image data generated by the ultrasonic sensor array. The third image data may, for example, correspond to at least one third reflected ultrasonic wave received by at least a portion of the ultrasonic sensor array from at least the portion of the target object. In some examples, the initial authentication process may be based at least in part on temporal changes in size, arrangement or other features indicated by the first, second and / or third image data. If the first, second and third image data are obtained at different times, such changes may be detected, for example, by comparing the feature size, arrangement, etc. indicated by the third image data with the feature size, arrangement, etc. indicated by the first image data and / or the second image data. This type of temporal change may be referred to herein as a "time-based feature difference." According to some embodiments, an activity indicator may be generated based on time-based feature differences. See below. Figure 3B and Figures 6A to 6C Describe some examples.

[0070] In some embodiments, the authentication process may include determining whether a fingerprint feature is present on or near the surface of the target object and whether a fingerprint feature is present under the surface of the target object. According to some embodiments, an indication that deception has been detected may be generated based at least in part on the difference between the fingerprint feature on the surface of the target object and the fingerprint feature under the surface of the target object. In some instances, the indication that deception has been detected may be an alert transmitted to another device and / or stored in a memory, such as information such as this document. According to some embodiments, if a surface fingerprint feature on the surface of the target object and a subsurface fingerprint feature under the surface of the target object are detected, then in response to an indication that deception has been detected, the control system may be configured to store the first image data, the second image data, the third image data, the fingerprint detail points, the fingerprint key points, or the fingerprint features. In this way, information about the hacker's fingerprint may be saved for future use. Some examples are described below.

[0071] In some examples, fingerprint features on the surface of the target object can be identified based on a registered fingerprint template. According to some examples, multiple image data can be collected in a subsurface area of ​​the target object based on the identified fingerprint features. An example is shown in Figure 4 and described below. In some such instances, the authentication process can be further based on multiple image data collected in the subsurface area. In some embodiments, the multiple image data can be collected from a portion of the ultrasonic sensor array. In some instances, the candidate user can be evaluated based at least in part on temporal or non-temporal changes in the multiple image data collected in the subsurface area. According to some instances, the legitimate user can be verified based on temporal or non-temporal changes in the multiple image data collected in the subsurface area.

[0072] According to some examples, the first acquisition time window may begin at the end time of the first acquisition time delay. In some examples, the second acquisition time window may begin at the end time of the second acquisition time delay. In some examples, the first acquisition time delay and the first acquisition time window may cause at least a portion of the first image data to correspond to fingerprint features of a target object. In some examples, the target object may be a finger of a person, such as a user's finger. In some such examples, the second acquisition time delay and the second acquisition time window may cause at least a portion of the second image data to correspond to subcutaneous features of the user's finger.

[0073] Figure 1D Some examples of acquisition time delays and acquisition time windows are shown. Figure 1D In FIG. 1 , the acquisition time delay is labeled "RGD," an acronym for "range-gate delay," and the acquisition time window is labeled "RGW," an acronym for "range-gate window." Graph 112 a shows a transmit signal 114 starting at time t 0 . Transmit signal 114 may be, for example, an ultrasonic pulse. In alternative embodiments, multiple ultrasonic pulses may be transmitted.

[0074] Graph 112b illustrates an example of a first acquisition time delay RGD1 and a first acquisition time window RGW1. Received wave 116a represents the reflected wave received by the ultrasonic sensor array and sampled during the first acquisition time window RGW1 after the first acquisition time delay RGD1. In some examples, the acquisition time delay may be in the range of approximately 10 nanoseconds to approximately 20,000 nanoseconds, or greater. In some embodiments, the first acquisition time window may be in the range of 5 to 50 nanoseconds, or approximately 5 to 50 nanoseconds. In some examples, "approximately" or "approximately" may mean within + / - 5%, while in other examples, "approximately" or "approximately" may mean within + / - 10%, + / - 15%, or + / - 20%. However, in some embodiments, the first acquisition time window may be in the range of 50 to 20,000 nanoseconds, or approximately 50 to 20,000 nanoseconds, or greater. According to some examples, device 101 may include a pressure plate. The pressure plate can be positioned relative to the ultrasonic sensor array 102. For example, the pressure plate can be positioned adjacent to and / or attached to the ultrasonic sensor array 102. In some such examples, the first acquisition time delay can correspond to an estimated amount of time that ultrasonic waves reflected from the pressure plate surface will be received by at least a portion of the ultrasonic sensor array 102. Accordingly, the first acquisition time delay and the first acquisition time window can be selected to capture one or more fingerprint features of a target object placed on the pressure plate surface. For example, in some embodiments having a pressure plate approximately 400 microns thick, the acquisition time delay (RGD) can be set to approximately 1,000 nanoseconds and the acquisition time window (RGW) can be set to approximately 50 nanoseconds.

[0075] Graph 112c illustrates an example of a second acquisition time delay RGD2 and a second acquisition time window RGW2. Received wave 116b represents the reflected wave received by the ultrasonic sensor array and sampled during the second acquisition time window RGW2, following the second acquisition time delay RGD2. In this example, the first acquisition time delay is equal to the second acquisition time delay. However, in other embodiments, the first acquisition time delay may not be equal to the second acquisition time delay. In this example, both the first acquisition time delay and the second acquisition time delay are measured from time t0. However, in other embodiments, the first acquisition time delay and the second acquisition time delay may be measured from different starting times. In some examples, the first acquisition time delay and / or the second acquisition time delay may correspond to the time required for a transmitted ultrasonic wave to reflect from the platen surface and be received by at least a portion of the ultrasonic sensor array.

[0076] According to some embodiments, the second acquisition time window can be in the range of 5 to 50 nanoseconds, or in the range of approximately 5 to 50 nanoseconds. However, in some embodiments, the second acquisition time window can be in the range of 50 to 2,000 nanoseconds, or in the range of approximately 50 to 2,000 nanoseconds. In some instances, the second acquisition time window can be in the range of 2,000 to 20,000 nanoseconds, or in the range of approximately 2,000 to 20,000 nanoseconds or greater. In some instances, the second acquisition time delay and the second acquisition time window can be selected to capture fingerprint features of the target object and subcutaneous features of the target object. For example, in some embodiments having a press plate of approximately 400 microns thick, the acquisition time delay (RGD) can be set to approximately 1,000 nanoseconds and the acquisition time window (RGW) can be set to approximately 1,000 nanoseconds.

[0077] Figures 2A to 2C Examples of A-scan, B-scan, and C-scan images are shown. Figure 2A As shown in FIG, an A-scan graph of reflection amplitude versus time can be obtained from a single ultrasound receiver or transceiver, such as a sensor pixel or a small group of sensor pixels. Figure 2A The high amplitude events shown in indicate reflections from within the target object (e.g., a finger) caused by acoustic impedance contrast within the target object. Bone surfaces, for example, typically have relatively high acoustic impedance compared to overlying tissue and therefore produce relatively high amplitude reflections. There are multiple reflections in the A-scan (e.g., Figure 2A Reflections 201 and 203 (shown in the figure) indicate that the target object is not, for example, air or a solid block of silicone rubber, or other such material that could be used for spoofing. The presence of such reflections, combined with fingerprint matching, would suggest that the target object is actually the finger of an authorized user. However, a fake finger can be made using multiple layers with different acoustic impedances. Furthermore, a legitimate user's fingerprint pattern on a sleeve slid over or placed on the hacker's finger can defeat this simple anti-spoofing method.

[0078] B-scan images, such as Figure 2B As shown in , it can be obtained from a single ultrasound receiver or transceiver row or column. In this example, the travel time is along the vertical axis of the B-scan image. Various reflections including reflections 205 and 207 can be seen in Figure 2B In the B-scan image of FIG. 2 , reflections 205 and 207 correspond to subcutaneous features of a finger in this example. Compared to the A-scan image data, the presence of such complex features provides a stronger indication that the target object is actually a finger.

[0079] C-scan images can be obtained from an ultrasound receiver or transceiver array, such as an ultrasound receiver or transceiver grid or a focused single element transceiver with arch and translation mechanical motion. Figure 2CIn the example shown in FIG, ultrasound image data has been obtained at a depth suitable for acquiring a 2-DC scan image of a subepidermal feature (e.g., a feature 209 corresponding to an area of ​​increased acoustic impedance contrast, such as a subepidermal vessel or aggregate of adipose tissue). The depth may correspond to a time interval (which may be referred to herein as an acquisition time delay or range gate delay (RGD)) between the time at which the ultrasound wave is transmitted and the time during which the reflected ultrasound wave is sampled. For example, a relatively large range gate delay may be selected to primarily receive reflected ultrasound waves from bones, and a relatively small range gate delay may be selected to primarily receive reflected ultrasound waves from ridges and valleys of fingerprints or subepidermal features (e.g., blood vessels, blood, muscle tissue features, or bone tissue features).

[0080] The amount of detail in the C-scan image provides an even stronger indication that the target object is actually a finger. Furthermore, sub-epidermal features are indicated with sufficient detail so that their corresponding attribute information can be used as part of the authentication process, such as those described below, such as unique C-scan features referenced in depth and offset relative to one or more fingerprint minutiae points of the legitimate user's finger.

[0081] Figure 2D An example of a cross-sectional view of a device capable of performing at least some of the methods described herein is shown. For example, device 101 may be capable of performing the methods described herein with reference to Figure 1C and 3A The method described. Apparatus 101 is an example of a device that may be included in a biometric identification system such as those disclosed herein. Here, apparatus 101 is an example of a device that may be included in a biometric identification system such as those disclosed herein. Figure 1B As with other embodiments shown and described herein, Figure 2D The component types, component arrangements, and component sizes described in the accompanying drawings are presented by way of example only.

[0082] Figure 2D 2 shows an example of ultrasonic waves reflected from a target object. In this example, the target object is a finger 206 that is insonified by the transmitted ultrasonic waves 214. In this example, the transmitted ultrasonic waves 214 are the same as those described above with reference to FIG. Figure 1D Here, the reflected ultrasonic wave 216 received by at least a portion of the ultrasonic sensor array 102 is Figure 1D However, other embodiments may include different types of transmitted ultrasonic waves 214 and / or reflected ultrasonic waves 216, including but not limited to: Figure 3B and 13 The examples are shown in FIG, which is described below.

[0083] In this example, the ultrasonic waves are emitted by an ultrasonic transmitter 108 that is separate from the ultrasonic sensor array 102. Figure 2D In the example shown in FIG, at least a portion of the device 101 includes an ultrasonic transmitter 108 that can function as a plane wave ultrasonic transmitter. In some embodiments, the ultrasonic transmitter 108 can include a piezoelectric transmitter layer having transmitter excitation electrodes disposed on each side of the piezoelectric transmitter layer.

[0084] In this example, the ultrasonic sensor array 102 can act as an ultrasonic receiver array. In some such examples, the ultrasonic sensor array 102 can include a pixel input electrode and sensor pixel array formed in part by a TFT circuit system, an overlying piezoelectric receiver layer 220 of a piezoelectric material (e.g., PVDF or PVDF-TrFE), and an upper electrode layer positioned on the piezoelectric receiver layer, the piezoelectric receiver layer sometimes referred to herein as a receiver bias electrode. Figure 15A and 15B Examples of suitable ultrasonic transmitters and ultrasonic receiver arrays are described.

[0085] However, in alternative embodiments, the ultrasonic sensor array 102 and ultrasonic transmitter 108 may be combined in an ultrasonic transceiver array. For example, in some embodiments, the ultrasonic sensor array 102 may include a piezoelectric receiver layer, such as a polyvinylidene fluoride (PVDF) polymer layer or a polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) copolymer layer. In some embodiments, a single piezoelectric layer may function as both an ultrasonic transmitter and a receiver. In some embodiments, other piezoelectric materials may be used in the piezoelectric layer, such as aluminum nitride (AlN) or lead zirconate titanate (PZT). In some embodiments, the ultrasonic sensor array 102 may include an array of ultrasonic transducer elements, such as a piezoelectric micromachined ultrasonic transducer (PMUT) array, a capacitive micromachined ultrasonic transducer (CMUT) array, and the like. In some such embodiments, a piezoelectric receiver layer, a PMUT element in a single-layer PMUT array, or a CMUT element in a single-layer CMUT array may function as both an ultrasonic transmitter and an ultrasonic receiver.

[0086] In this example, the transmitted ultrasonic wave 214 has been transmitted from the ultrasonic wave emitter 108 through the sensor stack 215 and into the overlying finger 206. In some examples, the different layers of the sensor stack 215 include one or more substrates of glass or other materials that are substantially transparent to visible light (such as plastic or sapphire). In this example, the sensor stack 215 includes a substrate 210 coupled to a light source system (not shown), which can be a backlight for a display according to some embodiments. In alternative embodiments, the light source system can be coupled to a front light. Thus, in some embodiments, the light source system can be configured to illuminate a display and a target object.

[0087] In this embodiment, substrate 210 is coupled to a thin-film transistor (TFT) substrate 212 of the ultrasonic sensor array 102. According to this example, a piezoelectric receiver layer 220 overlies the sensor pixels 202 of the ultrasonic sensor array 102, and a pressure plate 225 overlies the piezoelectric receiver layer 220. Thus, in this example, the device 101 is capable of transmitting ultrasonic waves 214 through one or more substrates of a sensor stack 215, which includes the ultrasonic sensor array 102 having the substrate 212 and the pressure plate 225, which can also be considered a substrate. In some embodiments, the sensor pixels 202 of the ultrasonic sensor array 102 can be transparent, partially transparent, or substantially transparent, so that the device 101 can transmit light from the light source system through the elements of the ultrasonic sensor array 102. In some embodiments, the ultrasonic sensor array 102 and associated circuitry can be formed on or in a glass, plastic, or silicon substrate.

[0088] Figure 2E An example of a mobile device that includes the biometric recognition system disclosed herein is shown. In this example, mobile device 250 is a smartphone. However, in alternative examples, mobile device 250 can be another type of mobile device, such as a mobile health device, such as a mobile drug delivery device, a wearable device, a tablet computer, etc.

[0089] In this example, mobile device 250 includes the Figure 1B2. An example of a device 101 is depicted. In this example, the device 101 is at least partially housed within a mobile device housing 255. According to this example, at least a portion of the device 101 is located in the portion of the mobile device 250 shown being touched by the finger 206, which portion of the mobile device corresponds to the location of the button 260. Thus, the button 260 can be an ultrasonic button. In some embodiments, the button 260 can function as a home button. In some embodiments, the button 260 can function as an ultrasonic authentication button, which has the ability to turn on or otherwise wake up the mobile device 250 when touched or pressed and / or authenticate or otherwise verify the user when running an application on the mobile device (e.g., a wake-up function) to ensure such functionality.

[0090] In this embodiment, mobile device 250 may be capable of performing a user authentication process. For example, the control system of mobile device 250 may be capable of comparing attribute information obtained from image data received via the ultrasonic sensor array of apparatus 101 with stored attribute information previously obtained from image data received from authorized users. In some examples, the attribute information obtained from the received image data and the stored attribute information may include attribute information corresponding to at least one of subcutaneous features, muscle tissue features, or bone tissue features.

[0091] According to some embodiments, the attribute information obtained from the received image data and the stored attribute information may include information about fingerprint minutiae or key points. In some such embodiments, the user authentication process may include evaluating information about fingerprint minutiae and at least one other type of attribute information, such as attribute information corresponding to subepidermal features. According to some such examples, the user authentication process may include evaluating information about fingerprint minutiae or key points and attribute information corresponding to vascular features. For example, attribute information obtained from a received image of blood vessels in a finger may be compared to a stored image of blood vessels in the authorized user's finger 206.

[0092] Figure 3A Is a flowchart containing blocks for alternative methods. Figure 3A The blocks of (and those of the other flow diagrams provided herein) may be, for example, Figure 1B 、 2D or 2E, or by a similar device. As with other methods disclosed herein, Figure 3A The methods outlined in the may include more or fewer blocks than indicated. Furthermore, the method blocks disclosed herein are not necessarily executed in the order indicated.

[0093] In this example, block 305 includes controlling the ultrasonic sensor array to acquire ultrasonic image data corresponding to at least one reflected ultrasonic wave received by at least a portion of the ultrasonic sensor array from the target object during an acquisition time window. According to some embodiments, a control system (e.g., control system 106) may be capable of controlling the ultrasonic sensor array, such as one of those disclosed herein. In some examples, if the target object is a finger, the acquisition time window may be selected to include images of both fingerprint features and subcutaneous features. According to some examples, the acquisition time window may be selected to detect common spoofing, which includes forming a fingerprint-like pattern on the outside of a sleeve or on the outside of a membrane that can be worn on or slid over a genuine finger. According to some embodiments, the acquisition time window may be in the range of 50 to 2000 nanoseconds, or approximately in the range of 50 to 2000 nanoseconds. However, in some embodiments, the acquisition time window may be in the range of 2000 to 10,000 nanoseconds, or approximately in the range of 2000 to 10,000 nanoseconds. In some examples, the acquisition time window can be in the range of 10,000 to 20,000 nanoseconds, or approximately 10,000 to 20,000 nanoseconds.

[0094] According to this example, block 310 includes extracting first fingerprint data from the ultrasound image data. Here, block 315 includes determining whether the ultrasound image data contains second fingerprint data that is different from the first fingerprint data. Figure 5 are shown in and described below. Figure 5 Visual inspection of the live user's finger shows prominent buckets and minutiae at the center of the live user's finger (overview 505) and similar prominent buckets and minutiae on the live user's finger applied to the spoof (overview 510), which can be distinguished by spatial displacement even when only a single image is acquired using a relatively long acquisition time window. The control system can execute an automated method that uses minutiae and / or key points associated with the spoof and potential live user to attempt to match them to one or more enrollment templates of the legitimate user using fingerprint matching software. An automated fingerprint identification system (AFIS) or similar fingerprint analysis software can be used to identify both the live user and the spoof.

[0095] In some instances, block 315 may include determining whether the depth difference between the depth of the first fingerprint data and the depth of the second fingerprint data corresponds to at least a threshold time difference, for example, a time difference greater than 50 nanoseconds. If the second fingerprint data is found at a different depth, this is strong evidence of the type of spoofing described above. For example, the second fingerprint data may correspond to the fingerprint of a hacker who has created a spoof with an image of the legitimate user's fingerprint and placed the spoof on the hacker's finger. In some instances, if the second fingerprint data is found at a different depth, the control system will not continue the authentication process. In some such instances, if the second fingerprint data is found at a different depth, the control system will not attempt to match the first or second fingerprint data to the stored fingerprint data.

[0096] In some embodiments, a spoofing attempt may be flagged. In some such instances, the control system may generate an indication of spoofing detected in response to a detected spoofing attempt. In some embodiments, the indication of spoofing detected may initiate a program that stores images, minutiae, and / or key points associated with the spoofed and hacker fingers. In some embodiments, when a fingerprint feature on the surface of a target object and a different fingerprint feature beneath the surface of the target object are detected, at least one of the ultrasonic image data, the first or second fingerprint data, the fingerprint minutiae, the fingerprint key points, and / or the fingerprint features may be stored. Specifically, if one of the fingerprints (e.g., spoofed) corresponds to an authorized or otherwise registered user of the mobile device, the stored images, image data, minutiae, key points, features, and / or fingerprint data may be retrieved later to attempt to identify the alleged hacker. In some instances, a timestamp and other location and / or user information of the spoofing attempt may also be stored for later use.

[0097] However, in this example, if it is determined that the ultrasound image data does not contain second fingerprint data that is different from the first fingerprint data, then the authentication process will be initiated based at least in part on the first fingerprint data. Some embodiments may include determining subcutaneous features from the ultrasound image data. In such examples, the authentication process may be based at least in part on the subcutaneous features.

[0098] Some examples may include performing a liveness determination. This liveness determination may be applicable to detecting spoofing where a fingerprint image is placed on a finger-like object, such as a finger-like object formed of rubber, silicon, or the like. Some such liveness determinations may include obtaining a first subcutaneous feature from first ultrasound image data at a first time and obtaining a second subcutaneous feature from second ultrasound image data at a second time. Some examples may include performing a liveness determination based on changes between the first subcutaneous feature and the second subcutaneous feature. This type of temporal change may correspond to blood flow within the finger, for example.

[0099] Figure 3BSome alternative examples of acquisition time delays and acquisition time windows are shown. Figure 3B The acquisition time delays and acquisition time windows shown in FIG may be adapted, for example, to the above reference Figure 1C and / or Figure 3A The method described.

[0100] Graph 320a shows transmitted signals 114a, 114b, and 114c, the first of which begins at time t0. In this example, transmitted signals 114a, 114b, and 114c are pulses of ultrasound. In alternative examples, a single ultrasound pulse may be transmitted. In some embodiments, the transmitted signal may include waveforms of other shapes (e.g., sinusoidal, triangular, rectangular, square, single-sided, double-sided, alternating, single frequency, multi-frequency, chirped, low duty cycle, high duty cycle, modulated, dual-modulated), or a combination of one or more such waveforms.

[0101] Graph 320b illustrates an example of a first acquisition time delay RGD1 and a first acquisition time window RGW1. Received wave packet (1) represents a reflected wave received by the ultrasonic sensor array and sampled during the first acquisition time window RGW1 after the first acquisition time delay RGD1. In some examples, the first acquisition time delay may correspond to the time required for a transmitted ultrasonic wave to reflect from the platen surface and be received by at least a portion of the ultrasonic sensor array.

[0102] In some instances, the first acquisition time window may be the same as that described above. Figure 3A The first acquisition time window may correspond to the acquisition time window described in block 305 of FIG. According to some examples, the first acquisition time window may be in the range of 50 to 2000 nanoseconds, or approximately in the range of 50 to 2000 nanoseconds. However, in some embodiments, the first acquisition time window may be in the range of 2000 to 10,000 nanoseconds, or approximately in the range of 2000 to 10,000 nanoseconds. In some examples, the first acquisition time window may be in the range of 10,000 to 20,000 nanoseconds, or approximately in the range of 10,000 to 20,000 nanoseconds. In some examples, the first acquisition time delay and the first acquisition time window may correspond to a fingerprint feature of the target subject and to one or more subcutaneous features of the target subject.

[0103] Graph 320c illustrates an example of a second acquisition time delay RGD2 and a second acquisition time window RGW2. Received wave packet (2) represents a reflected wave received by the ultrasonic sensor array and sampled during the second acquisition time window RGW2 after the second acquisition time delay RGD2. Graph 320d illustrates an example of an nth acquisition time delay RGDn and an nth acquisition time window RGWn, where n is an integer greater than 2. In some examples, n can be 3, 4, 5, etc. Received wave packet (n) represents a reflected wave received by the ultrasonic sensor array and sampled during the nth acquisition time window RGWn after the nth acquisition time delay RGDn.

[0104] In this example, the second acquisition time delay is equal to the nth acquisition time delay and the second acquisition time window is equal to the nth acquisition time window. According to some examples, graphs 320c and 320d may correspond to the process of acquiring ultrasound data for liveness determination from the same depth within the target object at two or more different times. Time-based characteristic differences between the ultrasound data may be evidence of liveness. In other embodiments, the second and nth acquisition time delays and / or the second and nth acquisition time windows may differ from each other.

[0105] In some embodiments, the second and nth acquisition time windows can be in the range of approximately 5 to 50 nanoseconds, or approximately 5 to 50 nanoseconds. However, in some embodiments, the second and nth acquisition time windows can be in the range of 50 to 2000 nanoseconds, or approximately 50 to 2000 nanoseconds. According to some examples, the second and nth acquisition time delays and time windows can correspond to subcutaneous features of the target object, such as vascular features.

[0106] In this example, the acquisition time delays are all measured from time t 0. However, in other embodiments, the acquisition time delays may be measured from different starting times.

[0107] Figure 4 An example of a fingerprint image superimposed on multiple subepidermal features is shown. Figure 4 In

[0065] , an acquisition time delay and a relatively long acquisition time window are selected in order to obtain a composite, overlapping, and self-referenced image of the leaflets (light gray spots, such as spot 405) and other subsurface features that are automatically overlaid on the fingerprint image. Figure 4This is done so that some of the light gray spots are easily referenced relative to the various fingerprint minutiae of the finger (e.g., ridge endings or bifurcations). In some such embodiments, the authentication process may be based on data extracted from both the fingerprint image and the image of the subepidermal features or from a single image containing both the fingerprint and the subepidermal features. For example, attribute information based on an ultrasonic image of the subepidermal features may reference attribute information based on an ultrasonic fingerprint image. According to some such embodiments, biometric template data corresponding to the subepidermal features may reference biometric template data corresponding to the fingerprint features (e.g., the location, orientation, and / or type of the fingerprint minutiae). In some embodiments, a composite image containing the fingerprint and the subepidermal features may be compared to a registered fingerprint template containing both the fingerprint and the subepidermal template information or only fingerprint-related template information for verification and authentication.

[0108] As mentioned above, some embodiments may include selecting an acquisition time delay and an acquisition time window to determine whether the sleeve or film on which the fingerprint is formed is located on the hacker's finger in the spoofing attempt. If so, two sets of overlapping fingerprint images may be acquired, one of the fake fingerprint and the other of the hacker's finger.

[0109] Figure 5 shows an example of overlapping fingerprint images. Figure 5 505 , a human finger (whose fingerprint is indicated in overview 505) is positioned behind a polydimethylsiloxane (PDMS) spoof finger having a thickness of approximately 0.5 mm, the spoof finger having a replica fingerprint (indicated in overview 510) simultaneously imaged with a 1" x 1" ultrasonic sensor array using a relatively large RGW. The spoof fingerprint and the real fingerprint may correspond, for example, to the above reference Figure 3A The first and second fingerprint data described. Figure 5 In the example shown in , the spoof fingerprint and the real fingerprint are intentionally offset for clarity. The control system can run fingerprint analysis software to authenticate the user based on the spoof fingerprint and the real fingerprint. In some embodiments, the fingerprint analysis software can properly identify the fingerprint of the authorized user regardless of the complexity of the additional minutiae and fingerprint features. If the number of fingerprint features exceeds the number of registered fingerprints, a spoofing attempt can be confirmed and additional images at different depths in the target object can be collected to verify the spoofing attempt. In some embodiments, a detected spoofing attempt can initiate a process to store fingerprint images, minutiae and / or key points associated with the spoof and hacker fingers for composite images and / or images at different depths. The stored images, minutiae and / or key points can be used later to identify the alleged hacker. The timestamp of the image capture can be stored together with the fingerprint image, minutiae and / or key points.

[0110] Some embodiments may include an authentication process based on both liveness determination and attribute information obtained from ultrasound image data corresponding to subcutaneous features. Some such embodiments may include acquiring image data corresponding to the subcutaneous features, determining biometric template data corresponding to the acquired image data, and comparing the determined biometric template data to stored biometric template data of a legitimate user.

[0111] Depending on the particular embodiment, activity determination can be performed in a variety of ways. In addition to providing information about subcutaneous features of the target object (e.g., structures within a finger), in some embodiments, temporal changes in the time difference between simple A-scan reflections acquired at two or more different times can be used to detect activity.

[0112] Figures 6A to 6C is a graph showing an example of the time difference between two A-scan reflections. Figure 6A An A-scan graph 605 acquired at a first time and an A-scan graph 610 acquired at a second time are shown. Figure 6B A-scan graphs 605 and 610 are shown superimposed along the same vertical axis. Figure 6C yes Figure 6B 6C in the dashed line. In this example, the time difference between A-scan graphs 605 and 610 is caused by tissue expansion and contraction as blood pulses through the finger's vasculature. This expansion and contraction due to the pulse activity is visible in the A-scan graph as a small shift in the flight time of the plotted return waves. Similar time variations can be determined from a related B-scan, C-scan, or volume scan (e.g., a combination of B-scans and / or C-scans).

[0113] Depth imaging and processing of captured images can take excessive power and processing capacity in a mobile device. In some embodiments, depth images of selected pores, hair follicles, or other epidermal or subepidermal features can be captured, analyzed, and compared to an enrollment template to detect spoofing attempts, minimizing processing time and power while confirming liveness and determining whether a user is authenticated or otherwise verified.

[0114] Figures 7 to 11B A flowchart is provided to provide additional examples of biometric system operation. Figures 7 to 11B The blocks of (and those of the other flow diagrams provided herein) may be, for example, Figure 1B The device 101 or similar device is executed. As with other methods disclosed herein, Figures 7 to 11B The methods outlined in the may include more or fewer blocks than indicated. Furthermore, the method blocks disclosed herein are not necessarily executed in the order indicated.

[0115] Figure 7An example of a registration and matching process utilizing fingerprints and skeletal structure is shown. During the registration process, in block 705, one or more fingers of a valid user may be registered. The registration process may generate a registration template containing information about the valid user's fingerprint (e.g., fingerprint minutiae or key points). The registration template may include additional registration information about the finger, such as skeletal structure, which in this example is obtained in block 710. Information about skeletal structure may include, for example, the distance from the epidermis to the bone surface, an overview of the phalanges, the distance from the epidermis to the nail bed, an overview of the nail bed, skeletal contours, and the like. The matching process may attempt to match the potential user's fingerprint information (block 715) and information about the skeletal structure and other subcutaneous features (block 720) with one or more registration templates. If the fingerprint and subcutaneous features match the registration template, the potential user may be authenticated or otherwise verified (block 725).

[0116] Figure 8A and 8B An example of the registration and matching process using fingerprints and bone structure is shown. Figure 8A The steps of the enrollment process for enrolling one or more fingerprints in block 805 are described. In block 810, one or more enrollment templates can be generated from the fingerprint information during enrollment. Additionally, the bone structure within the finger can be imaged in block 815. In some embodiments, in block 820, the bone structure can be referenced to selected fingerprint key points or minutiae. For example, triangulation can be used from various selected minutiae points to determine distances, offsets, and relative angles relative to the selected reference points. In block 825, the enrollment template with the bone structure information can be generated and stored. In some embodiments, the bone structure information can be stored in the same enrollment template as the fingerprint information.

[0117] In such Figure 8B During the matching process shown, the potential user's fingerprint is imaged in block 830, and an authentication template generated from the fingerprint information can be matched with one or more enrollment templates in block 835. If a match is determined, various bone structures or other subcutaneous features can be imaged in block 840 and matched with associated enrollment templates in block 845. If the fingerprint features and subcutaneous features match, the potential user can be authenticated in block 850. In some embodiments, if no bone structures or recognizable subcutaneous features are detected, an indication of spoofing detected can be generated in block 850.

[0118] Figure 9An example of a registration and matching process for detecting applied fingerprint spoofing (e.g., sleeve spoofing) is shown. During the registration process, one or more registration templates of the fingerprint of a legitimate user can be generated in block 905. In block 910, one or more registration templates of the subcutaneous layer of the legitimate user can be generated. During the matching process of blocks 915 and 920, an attempt to match the fingerprint and subcutaneous layer of the potential user can be made. In some embodiments, a spoofing attempt can be marked in block 925 when an underlying fingerprint is detected, such as when an applied spoof of a registered user is located above the hacker's finger. For example, a spoofing attempt can be marked by setting a detected spoofing indication (e.g., a spoofing detection output signal or a spoofing detection flag) to a positive value. If no spoofing is detected, the potential user can be authenticated or otherwise verified in block 930.

[0119] Figure 10A and 10B An example of the registration and matching process with fingerprints and pore / follicle locations is shown. Figure 10A In the example of FIG. 1 , a fingerprint image is acquired during block 1005 of the enrollment process. Fingerprint image data, such as fingerprint template data, may be determined from the fingerprint image and stored in some embodiments in block 1010. Pore and / or hair follicle feature locations, or other feature locations (e.g., subepidermal feature locations), may then be determined. A depth image of the selected pore and / or hair follicle features, or other features (e.g., subepidermal features), may then be generated in block 1015. An enrollment template corresponding to the pore and / or hair follicle image with or without fingerprint minutiae information may then be generated in block 1020 and stored for future reference.

[0120] exist Figure 10B In an example, a new fingerprint image is acquired during block 1025 of a subsequent authentication process. A determination may then be made in block 1030 as to whether the fingerprint data corresponding to the new fingerprint image matches the stored fingerprint data (e.g., fingerprint template data). Pore and / or hair follicle feature locations, or other feature locations (e.g., subepidermal feature locations), may then be determined in block 1035. A depth image of the selected pore and / or hair follicle features, or other features (e.g., subepidermal features), may then be generated in block 1040. An authentication template for the selected pore and / or hair follicle image may be determined. Verifying the authentication template for the selected pore and / or hair follicle image (block 1045) may include comparing the authentication template to an enrollment template. If both the fingerprint template data and the template for the selected pore and / or hair follicle image match the data stored during the enrollment process, the user may be authenticated in block 1050. In some embodiments, if the authentication template for the fingerprint fails to match the enrollment template for the fingerprint, steps associated with subsurface imaging may be omitted to reduce processing time and power consumption.

[0121] Figure 11A and 11B An example of the registration and matching process with depth distribution and time variation is shown. Figure 11A During the enrollment process shown in FIG, one or more fingerprints of a valid user may be enrolled in block 1105. One or more fingerprint templates may be generated in block 1110. Bone structure, blood vessels, and other subcutaneous structures may be imaged in block 1115, for example, using a selected range gating delay and range gating window. The bone structure, blood vessels, and other subcutaneous features may be referenced to fingerprint key points or minutiae in block 1120. During enrollment, various images may be acquired in block 1125 and temporal changes in the bone structure, blood vessels, or other subcutaneous features may be sampled, such as changes in the overview of a bone or fat lobules relative to one or more minutiae or other reference points. A template having the bone structure, blood vessels, or other subcutaneous features and their characteristic temporal changes may be generated in block 1130 and stored as a separate enrollment template or added to the fingerprint enrollment template.

[0122] exist Figure 11B During the matching process shown in FIG, a potential user's fingerprint can be imaged in block 1135 and matched to one or more stored enrollment templates in block 1140. If a match is found, the skeletal structure, blood vessels, or other subcutaneous features can be imaged in block 1145 and matched to the stored enrollment templates in block 1150. If a match is successful, the temporal variation of the skeletal structure, blood vessels, or other subcutaneous features relative to one or more fingerprint minutiae or reference points can be sampled in block 1155 and compared to the temporal information stored in the enrollment templates. The potential user can be authenticated in block 1160 based on the matching of the fingerprint, subcutaneous features, and / or temporal variation. In some embodiments, liveness can be determined from the temporal variation in block 1160. A liveness indicator can be generated in block 1160 based on time-based feature differences between two or more subcutaneous images. An indication of detected spoofing can be generated in block 1160 based on the absence or presence of differences and temporal variation between the fingerprint features on the surface of the target object and the fingerprint features beneath the surface of the target object.

[0123] During the conventional process of acquiring fingerprint images, only 2D images are typically captured. These 2D fingerprint images lack certain information related to the actual geometry of the fingerprint, such as ridge-valley depth. Some forms of spoof fingerprints may not possess these 3D features. Therefore, evaluating these 3D features can increase the accuracy of the fingerprint matching process and is at least one factor in the spoof detection process.

[0124] Thus, some embodiments include acquiring a 3D image of at least a portion of a target object.In some instances, the 3D image may be obtained from a relatively shallow depth and may be a 3D image of a fingerprint.

[0125] Figure 12 An example of a 3D image of a fingerprint is shown. Figure 12 The dimensions shown are examples only. Some embodiments may include acquiring ultrasound image data at one or more depths suitable for acquiring one or more 3D images of subcutaneous features. As mentioned above, the depth may correspond to a selected acquisition time delay. In some embodiments, a 3D or volumetric image of a finger may be constructed from a plurality of A-scan images, B-scan images, or C-scan images.

[0126] In some examples, the control system may be capable of acquiring first to Nth ultrasound image data during first to Nth acquisition time windows after first to Nth acquisition time delays. Each of the first to Nth acquisition time delays may correspond to first to Nth depths within the target object. For example, a volumetric image of a finger or a finger portion may be generated by acquiring image data multiple times at different depths of the finger or along specific finger features (e.g., hair follicles or sweat pores).

[0127] Some embodiments may include selecting one or more acquisition time delays and / or acquisition time windows (also referred to as range gating windows or RGWs) as part of the authentication or spoofing detection process. For example, if a sleeve with a fingerprint formed thereon is placed on or over a hacker's finger, a relatively uniform layer of the sleeve should exist between the fake fingerprint and the hacker's finger, with the hacker's finger not containing subepidermal features that are characteristic of a finger. Therefore, to assess whether a sleeve with a fingerprint formed thereon was placed over a hacker's finger in a spoofing attempt, one or more acquisition time delays with a relatively short RGW can be selected to determine whether a layer exists beneath the fingerprint layer that does not appear to contain features that are characteristic of a finger. Some such embodiments may include selecting one or more acquisition time delays and acquisition time windows suitable for determining whether a second fingerprint exists beneath the sleeve / non-finger layer (e.g., a legitimate user's fingerprint is located above a spoofed fingerprint). Some embodiments may include selecting one or more finger features (e.g., sweat pores) and imaging the sweat pore region at different depths within the finger surface to verify that the features are continuous and characteristic of a legitimate user's finger and not a spoof.

[0128] Alternatively or additionally, some embodiments may include selecting one or more acquisition time windows as part of an authentication or spoof detection process. In some such instances, an acquisition time delay and a relatively long acquisition time window may be selected to acquire image data comprising a fingerprint image superimposed on one or more subcutaneous feature images.

[0129] In some embodiments, a receiver bias control signal can be applied to a receiver bias electrode coupled to a piezoelectric receiver layer associated with an ultrasonic sensor array. The ultrasonic sensor array can include an array of sensor pixel circuits configured on a silicon, glass, or plastic substrate. In some embodiments, the sensor pixel circuits can include a collection of silicon or thin film transistors, capacitors, and diodes for calibrating and capturing signal information when the piezoelectric receiver layer receives ultrasonic waves. One or more ultrasonic waves can be emitted from an ultrasonic transmitter and reflected from a pressure plate surface coupled to the ultrasonic sensor array. Due to the acoustic impedance mismatch between the pressure plate and portions of the finger (e.g., ridges and valleys), a finger or other target object placed on the pressure plate surface can be imaged. The amplitude of the reflected wave depends in part on the degree of acoustic impedance mismatch at the pressure plate surface. Selecting an appropriate RGD and a relatively narrow RGW allows images of the fingerprint ridges and valleys at the pressure plate surface to be captured by the ultrasonic sensor array.

[0130] Figure 13 Examples of multiple acquisition time delays selected to receive acoustic waves reflected from different depths are shown. In these examples, each of the acquisition time delays (which are Figure 13 The range gate delay (denoted as RGD) is measured from the start time t1 of the transmit signal 1305 shown in graph 1300. Graph 1310 depicts reflected acoustic waves (received wave (1) is an example) that may be received by the ultrasonic sensor array at acquisition time delay RGD1 and sampled during acquisition time window RGW1. Such acoustic waves will typically be reflected from a relatively shallow portion of the platen closest to the biometric system or a target object placed thereon.

[0131] Graph 1315 depicts reflected acoustic waves (received wave (2) is one example) received by at least a portion of the ultrasonic sensor array at an acquisition time delay RGD2 (where RGD2>RGD1) and sampled during acquisition time window RGW2. Such acoustic waves will typically be reflected from a relatively deeper portion of the target object. Graph 1320 depicts reflected acoustic waves (received wave (n) is one example) received at an acquisition time delay RGDn (where RGDn>RGD2>RGD1) and sampled during acquisition time window RGWn. Such acoustic waves will typically be reflected from an even deeper portion of the target object.

[0132] The range gate delay is typically an integer multiple of the clock period. A clock frequency of 128 MHz, for example, has a clock period of 7.8125 nanoseconds, and RGD can range from less than 10 nanoseconds to more than 20,000 nanoseconds.

[0133] Similarly, the range gating window can also be an integer multiple of the clock period, but is typically much shorter than the RGD (e.g., less than about 50 nanoseconds) to capture the return signal while maintaining good axial resolution. In some embodiments, the acquisition time window (RGW) can be between about 10 nanoseconds and about 200 nanoseconds. In some examples, the RGW can be less than 10 nanoseconds, for example, 5 nanoseconds, 6 nanoseconds, 7 nanoseconds, or 8 nanoseconds. Such embodiments can be advantageous for acquiring ultrasonic data for 3D images (e.g., 3D fingerprint images). However, in some examples, the RGW can be greater than 200 nanoseconds.

[0134] Increasing the duration of the range-gate pulse width while maintaining RGD constant allows the sensor pixel circuit to capture reflected ultrasonic peaks corresponding to the fingerprint ridges and valleys and corresponding to subcutaneous features that can be captured during the time that RGW is active. Increasing RGD allows imaging deeper into the subcutaneous features of the finger.

[0135] It should be noted that while the various image bias levels (e.g., Tx block, Rx Sample, and Rx Hold, which may be applied to the Rx bias electrodes) may be in the single or low double volt range, the return signal may have a voltage of tens or hundreds of millivolts. In some embodiments, a receiver bias control signal having two or more levels representing selected RGD and RGW may be applied to the receiver bias electrodes of the ultrasonic sensor array. In some embodiments, a diode bias control signal applied to the sensor pixel circuits within the ultrasonic sensor array may contain two or more levels representing selected RGD and RGW. In some embodiments, a portion of the sensor pixel circuits (e.g., a pixel block, pixel row, or pixel subarray) may be used to acquire one or more images of a subsurface region of a target object at a desired depth and location to increase frame rate and reduce image processing requirements.

[0136] Figure 14Representatively depicting aspects of a 4×4 pixel array of sensor pixels for an ultrasonic sensor system. For example, each pixel 1434 may be associated with a localized area of ​​piezoelectric sensor material (PSM), a peak detection diode (D1), and a read transistor (M3); many or all of these components may be formed on or in a substrate to form pixel circuitry 1436. In practice, the localized area of ​​piezoelectric sensor material in each pixel 1434 can convert received ultrasonic energy into electrical charge. Peak detection diode D1 can register the maximum amount of charge detected by the localized area of ​​piezoelectric sensor material PSM. Each row of pixel array 1435 can then be scanned, for example, via a row select mechanism, gate driver, or shift register, and the read transistor M3 of each column can be triggered to allow the magnitude of the peak charge of each pixel 1434 to be read by additional circuitry, such as a multiplexer and A / D converter. Pixel circuitry 1436 may include one or more TFTs to allow pixels 1434 to be selected, addressed, and reset.

[0137] Each pixel circuit 1436 may provide information about a small portion of an object detected by the ultrasonic sensor system. Figure 14 The example shown in Figure 1 has a relatively coarse resolution, but ultrasonic sensors with a resolution of approximately 500 pixels per inch or higher can be configured with appropriately scaled structures. The detection area of ​​the ultrasonic sensor system can be selected based on the intended detection target. For example, the detection area can range from approximately 5 mm x 5 mm for one finger to approximately 3 inches x 3 inches for four fingers. Smaller and larger areas, including square, rectangular, and non-rectangular geometries, may be suitable for target objects.

[0138] Figure 15A An example of an exploded view of an ultrasonic sensor system is shown. In this example, the ultrasonic sensor system 1500a includes an ultrasonic transmitter 20 and an ultrasonic receiver 30 below a pressure plate 40. According to some embodiments, the ultrasonic receiver 30 may be Figure 1B An example of an ultrasonic sensor array 102 is shown in FIG. 1 and described above. In some embodiments, the ultrasonic transmitter 20 may be Figure 1Band described above. The ultrasonic transmitter 20 may include a substantially planar piezoelectric transmitter layer 22 and may be capable of functioning as a plane wave generator. Ultrasonic waves can be generated by applying a voltage to the piezoelectric layer, causing it to expand or contract, depending on an applied signal, thereby generating a plane wave. In this example, the control system 106 may be capable of causing a voltage to be applied to the planar piezoelectric transmitter layer 22 via a first transmitter electrode 24 and a second transmitter electrode 26. In this manner, ultrasonic waves can be generated by varying the thickness of the layer via the piezoelectric effect. Such ultrasonic waves can travel through the platen 40 toward a finger (or other object to be detected). A portion of the wave not absorbed or transmitted by the object to be detected is reflected back through the platen 40 and received by at least a portion of the ultrasonic receiver 30. The first and second transmitter electrodes 24 and 26 may be metallized electrodes, for example, layers of metal coating opposing sides of the piezoelectric transmitter layer 22.

[0139] The ultrasonic receiver 30 may include an array of sensor pixel circuits 32 disposed on a substrate 34 (which may also be referred to as a backplane), and a piezoelectric receiver layer 36. In some embodiments, each sensor pixel circuit 32 may include one or more TFT elements, electrical interconnect traces, and (in some embodiments) one or more additional circuit elements (e.g., diodes, capacitors, and the like). Each sensor pixel circuit 32 may be configured to convert charge generated in the piezoelectric receiver layer 36 proximal to the pixel circuit into an electrical signal. Each sensor pixel circuit 32 may include a pixel input electrode 38 that electrically couples the piezoelectric receiver layer 36 to the sensor pixel circuit 32.

[0140] In the illustrated embodiment, a receiver bias electrode 39 is disposed on a side of the piezoelectric receiver layer 36 proximate the platen 40. The receiver bias electrode 39 can be a metallized electrode and can be grounded or biased to control which signals can be passed to the sensor pixel circuit array 32. Ultrasonic energy reflected from the exposed (top) surface of the platen 40 can be converted into localized charges by the piezoelectric receiver layer 36. These localized charges can be collected by the pixel input electrodes 38 and passed to the underlying sensor pixel circuits 32. The charges can be amplified or buffered by the sensor pixel circuits 32 and provided to the control system 106.

[0141] The control system 106 can be electrically connected (directly or indirectly) to the first and second transmitter electrodes 24, 26, as well as to the receiver bias electrodes 39 and the sensor pixel circuitry 32 on the substrate 34. In some implementations, the control system 106 can operate generally as described above. For example, the control system 106 can be capable of processing the amplified signal received from the sensor pixel circuitry 32.

[0142] The control system 106 may be capable of controlling the ultrasonic transmitter 20 and / or the ultrasonic receiver 30 to acquire ultrasonic image data, for example, by acquiring a fingerprint image. Whether or not the ultrasonic sensor system 1500a includes the ultrasonic transmitter 20, the control system 106 may be capable of acquiring attribute information from the ultrasonic image data. In some examples, the control system 106 may be capable of controlling access to one or more devices based, at least in part, on the attribute information. The ultrasonic sensor system 1500a (or a related device) may include a memory system comprising one or more memory devices. In some embodiments, the control system 106 may include at least a portion of the memory system. The control system 106 may be capable of acquiring attribute information from the ultrasonic image data and storing the attribute information in the memory system. In some embodiments, the control system 106 may be capable of capturing a fingerprint image, acquiring attribute information from the fingerprint image, and storing the attribute information obtained from the fingerprint image (which may be referred to herein as fingerprint image information) in the memory system. According to some examples, the control system 106 may be capable of capturing a fingerprint image, acquiring attribute information from the fingerprint image, and storing the attribute information obtained from the fingerprint image even while the ultrasonic transmitter 20 is in an "off" state.

[0143] In some embodiments, the control system 106 may be capable of operating the ultrasonic sensor system 1500a in either an ultrasonic imaging mode or a force sensing mode. In some embodiments, the control system may be capable of maintaining the ultrasonic transmitter 20 in an "off" state when operating the ultrasonic sensor system in the force sensing mode. When the ultrasonic sensor system 1500a is operating in the force sensing mode, the ultrasonic receiver 30 may be capable of functioning as a force sensor. In some embodiments, the control system 106 may be capable of controlling other devices, such as a display system, a communication system, etc. In some embodiments, the control system 106 may be capable of operating the ultrasonic sensor system 1500a in a capacitive imaging mode.

[0144] The pressure plate 40 can be any suitable material that can acoustically couple to the receiver, with examples including plastic, ceramic, sapphire, metal, and glass. In some embodiments, the pressure plate 40 can be a cover plate, such as a display cover glass or lens glass. Particularly when the ultrasonic transmitter 20 is in use, fingerprint detection and imaging can be performed with a relatively thick pressure plate (e.g., 3 mm and above), if necessary. However, for embodiments in which the ultrasonic receiver 30 is capable of imaging fingerprints in force detection mode or capacitive detection mode, a thinner and relatively more flexible pressure plate 40 may be desirable. According to some such embodiments, the pressure plate 40 may comprise one or more polymers (e.g., one or more types of parylene) and may be substantially thinner. In some such embodiments, the pressure plate 40 may be tens of microns thick, or even less than 10 microns thick.

[0145] Examples of piezoelectric materials that can be used to form the piezoelectric receiver layer 36 include piezoelectric polymers having suitable acoustic wave properties (e.g., an acoustic impedance between approximately 2.5 MRayls and 5 MRayls). Specific examples of piezoelectric materials that can be used include ferroelectric polymers, such as polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) copolymers. Examples of PVDF copolymers include 60:40 (mol %) PVDF-TrFE, 70:30 PVDF-TrFE, 80:20 PVDF-TrFE, and 90:10 PVDR-TrFE. Other examples of piezoelectric materials that can be used include polyvinylidene chloride (PVDC) homopolymers and copolymers, polytetrafluoroethylene (PTFE) homopolymers and copolymers, and diisopropylamine bromide (DIPAB).

[0146] The thickness of each of the piezoelectric transmitter layer 22 and the piezoelectric receiver layer 36 can be selected to be suitable for generating and receiving ultrasonic waves. In one example, the PVDF planar piezoelectric transmitter layer 22 is approximately 28 μm thick, and the PVDF-TrFE receiver layer 36 is approximately 12 μm thick. Example frequencies of ultrasonic waves can be in the range of 5 MHz to 30 MHz, with wavelengths of approximately one millimeter or less.

[0147] Figure 15B An exploded view of an alternative example of an ultrasonic sensor system is shown. In this example, the piezoelectric receiver layer 36 has been formed into discrete elements 37. Figure 15B , each of the discrete elements 37 corresponds to a single pixel input electrode 38 and a single sensor pixel circuit 32. However, in alternative embodiments of the ultrasonic sensor system 1500b, there need not be a one-to-one correspondence between each of the discrete elements 37, the single pixel input electrodes 38, and the single sensor pixel circuits 32. For example, in some embodiments, there may be multiple pixel input electrodes 38 and sensor pixel circuits 32 for a single discrete element 37.

[0148] Figure 15A and 15BWhile an example arrangement of ultrasonic transmitters and receivers in an ultrasonic sensor system is shown, other arrangements are possible. For example, in some embodiments, the ultrasonic transmitter 20 may be above the ultrasonic receiver 30 and therefore closer to the object to be detected. In some embodiments, the ultrasonic transmitter may be included in an ultrasonic sensor array (e.g., a single layer of transmitters and receivers). In some embodiments, the ultrasonic sensor system may include an acoustic delay layer. For example, the acoustic delay layer may be incorporated into the ultrasonic sensor system between the ultrasonic transmitter 20 and the ultrasonic receiver 30. The acoustic delay layer can be used to adjust the timing of ultrasonic pulses while electrically insulating the ultrasonic receiver 30 from the ultrasonic transmitter 20. The acoustic delay layer can have a substantially uniform thickness, with the material used for the delay layer and / or the thickness of the delay layer selected to provide a desired delay in the time it takes for reflected ultrasonic energy to reach the ultrasonic receiver 30. This allows energy pulses carrying information about an object, which is reflected by the object, to reach the ultrasonic receiver 30 during a time range when energy reflected from other parts of the ultrasonic sensor system is unlikely to reach the ultrasonic receiver 30. In some embodiments, substrate 34 and / or platen 40 may act as an acoustic delay layer.

[0149] As used herein, a phrase referring to "at least one" of a list of items refers to any combination of those items, including single members. As an example, "at least one of a, b, or c" is intended to encompass: a, b, c, ab, ac, bc, and abc.

[0150] The various illustrative logics, logical blocks, modules, circuits, and algorithmic processes described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or a combination of both. The interchangeability of hardware and software has been generally described in terms of functionality and illustrated in the various illustrative components, blocks, modules, circuits, and processes described above. Whether this functionality is implemented as hardware or software depends on the specific application and design constraints imposed on the overall system.

[0151] The hardware and data processing equipment described in conjunction with the aspects disclosed herein to implement the various illustrative logics, logic blocks, modules, and circuits may be implemented or performed by a general-purpose single-chip or multi-chip processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor or any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration. In some embodiments, particular processes and methods may be performed by circuits specific to a given function.

[0152] In one or more aspects, the functions described may be implemented in hardware, digital electronic circuitry, computer software, firmware (including the structures disclosed in this specification and their structural equivalents), or any combination thereof. Implementations of the subject matter described in this specification may also be implemented as one or more computer programs (i.e., one or more modules of computer program instructions) encoded on computer storage media for execution by, or to control the operation of, data processing apparatus.

[0153] If implemented in software, the functions may be stored as one or more instructions or codes on or transmitted via a computer-readable medium (e.g., a non-transitory medium). The processes of the methods or algorithms disclosed herein may be implemented in a processor-executable software module that may reside on a computer-readable medium. Computer-readable media include both computer storage media and communication media, with communication media including any media that can be enabled to transfer a computer program from one place to another. Storage media may be any available medium accessed by a computer. By way of example and not limitation, these computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage devices, magnetic disk storage devices or other magnetic storage devices, or any other media that can be used to store the desired program code in the form of instructions or data structures and that can be accessed by a computer. Furthermore, any connection may be appropriately referred to as a computer-readable medium. Disks and optical disks, as used herein, include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically, while optical discs use lasers to reproduce data optically. Combinations of the above should also be included within the scope of computer-readable media. Additionally, the operations of a method or algorithm may reside as any one or any combination or set of codes and instructions on machine-readable media and computer-readable media that can be incorporated into a computer program product.

[0154] Various modifications to the embodiments described herein will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the claims, the principles and novel features disclosed herein. The word "exemplary" is used exclusively herein (if at all) to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" should not necessarily be construed as preferred or advantageous over other embodiments.

[0155] Certain features described in this specification in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of separate embodiments may also be implemented individually in multiple embodiments or in any suitable subcombination. Furthermore, while features may be described above as functioning in certain combinations and even initially claimed as such, in some cases one or more features from a claimed combination may be deleted from the combination, and the claimed combination may be directed to subcombinations or variations of subcombinations.

[0156] Similarly, although operations are depicted in a particular order in the accompanying drawings, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Furthermore, the separation of various system components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. In addition, other embodiments are within the scope of the appended claims. In some cases, the actions recited in the claims can be performed in different orders and still achieve the desired result.

[0157] It will be understood that unless it is explicitly indicated that the features in any of the specifically described embodiments are incompatible with each other, or the surrounding context implies that they are mutually exclusive and not easily combined in a complementary and / or supportive sense, the entire content of the present invention anticipates and envisions that the specific features of those complementary embodiments may be selectively combined to provide one or more comprehensive, but slightly different technical solutions. Therefore, it will be further understood that the above description has been given by way of example only, and detailed modifications may be made within the scope of the present invention.

Claims

1. A device for authentication, comprising: Ultrasonic sensor array; Memory system; as well as a control system, at least a portion of which is coupled to the ultrasonic sensor array, the control system being configured to: Acquiring first image data generated by the ultrasonic sensor array, the first image data corresponding to at least one first reflected ultrasonic wave received from a target object by at least a portion of the ultrasonic sensor array during a first acquisition time window; acquiring second image data generated by the ultrasonic sensor array, the second image data corresponding to at least one second reflected ultrasonic wave received from the target object by at least a portion of the ultrasonic sensor array during a second acquisition time window shorter than the first acquisition time window; as well as An authentication process is initiated based on the first image data and the second image data. 2 . The apparatus of claim 1 , wherein the first acquisition time window starts at an end time of a first acquisition time delay and wherein the second acquisition time window starts at an end time of a second acquisition time delay. 3 . The apparatus of claim 2 , wherein the first acquisition time delay and the second acquisition time delay are not of equal duration.

4. The apparatus of claim 2 , wherein the apparatus comprises a platen positioned relative to the ultrasonic sensor array and wherein the first acquisition time delay corresponds to an expected amount of time that ultrasonic waves reflected from a surface of the platen will be received by at least a portion of the ultrasonic sensor array. 5 . The apparatus of claim 2 , wherein the first acquisition time delay and the first acquisition time window are such that the first image data corresponds to a fingerprint feature of the target object and to a first subcutaneous feature of the target object. 6 . The apparatus of claim 5 , wherein the second acquisition time delay and the second acquisition time window are such that the second image data corresponds to a second subcutaneous feature of the target object.

7. The apparatus of claim 1 , wherein the target object comprises a user's finger, and at least a portion of the first image data represents at least one fingerprint feature of the user's finger, and at least a portion of the second image data represents at least one subcutaneous feature of the user's finger.

8. The apparatus of claim 1 , wherein the control system is further configured to acquire third image data generated by the ultrasonic sensor array, the third image data corresponding to at least one third reflected ultrasonic wave received by at least the portion of the ultrasonic sensor array from the target object, and wherein the authentication process initiated is based at least in part on identifying a time-based characteristic difference of the target object between the third image data and the first image data or the second image data.

9. The apparatus of claim 8, wherein the initiated authentication process generates an activity indicator based at least in part on the time-based characteristic differences of the target object.

10. The apparatus of claim 1, wherein the authentication process involves detecting one or more surface fingerprint features on a surface of the target object and one or more subsurface fingerprint features below the surface of the target object.

11. The apparatus of claim 10, wherein the initiated authentication process generates an indication that spoofing was detected based on a difference between at least one of the one or more surface fingerprint features and at least one of the one or more subsurface fingerprint features.

12. The apparatus of claim 1, wherein the control system comprises at least one processor.

13. The apparatus according to claim 1, wherein As part of the initiation of the authentication process, fingerprint features on the surface of the target object are identified based on a registered fingerprint template, and the initiation of the authentication process is further based on multiple image data, which are collected in the subsurface area of ​​the target object based on the identified fingerprint features.

14. The apparatus of claim 13, wherein the candidate user is authenticated based at least in part on the presence or absence of one or more temporal changes in the plurality of image data collected in the subsurface region.

15. The apparatus of claim 1, wherein the control system comprises a sensor controller and an application processor.

16. An authentication method, comprising: Acquiring first image data generated by the ultrasonic sensor array, the first image data corresponding to at least one first reflected ultrasonic wave received from a target object by at least a portion of the ultrasonic sensor array during a first acquisition time window; acquiring second image data generated by the ultrasonic sensor array, the second image data corresponding to at least one second reflected ultrasonic wave received from the target object by at least a portion of the ultrasonic sensor array during a second acquisition time window shorter than the first acquisition time window; as well as An authentication process is initiated based on the first image data and the second image data.

17. The method of claim 16, wherein the first acquisition time window starts at an end time of a first acquisition time delay and wherein the second acquisition time window starts at an end time of a second acquisition time delay. The method of claim 17 , wherein the first acquisition time delay and the second acquisition time delay are not of equal duration.

19. The method of claim 17, wherein the first acquisition time delay or the second acquisition time delay corresponds to an expected amount of time that ultrasonic waves reflected from a surface of a platen will be received by the ultrasonic sensor array.

20. The method of claim 17, wherein the first acquisition time delay and the first acquisition time window are such that the first image data corresponds to a fingerprint feature of the target subject and to a first subcutaneous feature of the target subject.

21. The method of claim 20, wherein the second acquisition time delay and the second acquisition time window are such that the second image data corresponds to a second subcutaneous feature of the target object.

22. The method of claim 16, further comprising: In response to detecting surface fingerprint features on the surface of the target object and subsurface fingerprint features below the surface of the target object, at least one of the first image data, the second image data, fingerprint minutiae points, fingerprint key points, or fingerprint features is stored.

23. A non-transitory medium having stored thereon software, the software comprising instructions for controlling one or more devices to: Acquiring first image data generated by the ultrasonic sensor array, the first image data corresponding to at least one first reflected ultrasonic wave received from a target object by at least a portion of the ultrasonic sensor array during a first acquisition time window; acquiring second image data generated by the ultrasonic sensor array, the second image data corresponding to at least one second reflected ultrasonic wave received from the target object by at least a portion of the ultrasonic sensor array during a second acquisition time window shorter than the first acquisition time window; and An authentication process is initiated based on the first image data and the second image data.

24. The non-transitory medium of claim 23, wherein the first acquisition time window starts at an end time of a first acquisition time delay and wherein the second acquisition time window starts at an end time of a second acquisition time delay.

25. The non-transitory medium of claim 24, wherein the first acquisition time delay and the second acquisition time delay are not of equal duration.

26. The non-transitory medium of claim 24, wherein the first acquisition time delay or the second acquisition time delay corresponds to an expected amount of time that ultrasonic waves reflected from a surface of a platen will be received by the ultrasonic sensor array.

27. The non-transitory medium of claim 24, wherein the first acquisition time delay and the first acquisition time window are such that the first image data corresponds to a fingerprint feature of the target subject and to a first subcutaneous feature of the target subject.

28. The non-transitory medium of claim 27, wherein the second acquisition time delay and the second acquisition time window are such that the second image data corresponds to a second subcutaneous feature of the target object.

29. A device for authentication, comprising: means for acquiring first image data generated by the ultrasonic sensor array, the first image data corresponding to at least one first reflected ultrasonic wave received from a target object by at least a portion of the ultrasonic sensor array during a first acquisition time window; means for acquiring second image data generated by the ultrasonic sensor array, the second image data corresponding to at least one second reflected ultrasonic wave received from the target object by at least a portion of the ultrasonic sensor array during a second acquisition time window shorter than the first acquisition time window; as well as Means for initiating an authentication process based on the first image data and the second image data.

30. The apparatus of claim 29, wherein the first acquisition time window starts at an end time of a first acquisition time delay and wherein the second acquisition time window starts at an end time of a second acquisition time delay, and wherein the first acquisition time delay and the second acquisition time delay do not have equal durations.

Images