Abstract: Certain aspects of the present disclosure provide techniques and apparatus for scanning fingerprints in a biometric security system. An example method generally includes receiving a plurality of images of a fingerprint of a user, aligning the plurality of images, and merging the aligned plurality of images into a fused fingerprint image. The fused fingerprint image is output for analysis against a reference fingerprint image associated with the user.

Abstract: An apparatus 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 that is 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.

Abstract: Systems, methods and apparatus for configuring a fingerprint sensor to operate in a capacitive sensing mode and an ultrasonic sensing mode are disclosed. A fingerprint sensor may be configured to operate in a capacitive sensing mode by driving a sensing electrode using a controller. In some implementations, an object positioned on or near the sensing electrode may be detected using the fingerprint sensor in the capacitive sensing mode, and the controller can drive electrodes of the fingerprint sensor differently to configure the fingerprint sensor to operate in an ultrasonic sensing mode. In some implementations, an applications processor may be instructed to authenticate a fingerprint of the object from image data obtained when the fingerprint sensor is operating in the ultrasonic sensing mode. In some implementations, a display of a mobile device containing the fingerprint sensor may be unlocked, or the mobile device may be woken up when the fingerprint is authenticated.

Abstract: Systems and methods for multi-spectral ultrasonic imaging are disclosed. In one embodiment, a finger is scanned at a plurality of ultrasonic scan frequencies. Each scan frequency provides an image information set describing a plurality of pixels of the finger including a signal-strength indicating an amount of energy reflected from a surface of a platen on which a finger is provided. For each of the pixels, the pixel output value corresponding to each of the scan frequencies is combined to produce a combined pixel out put value for each pixel. Systems and methods for improving the data capture of multi-spectral ultrasonic imaging are also disclosed.

Abstract: This disclosure provides some implementations of systems, methods and apparatus associated with a drive scheme for ultrasonic transducer pixel readout. In some implementations, a piezoelectric ultrasonic transducer has a first electrode, a second electrode, and a piezoelectric layer disposed between the first and second electrodes. The second electrode is coupled with a sampling node. A sampling diode has an input and an output. The input is coupled to receive a diode bias signal. The output is coupled with the sampling node. Controller circuitry is configured to control the diode bias signal to at least partially drive a voltage at the sampling node. Read circuitry is coupled with the sampling node to read the voltage.

Abstract: An apparatus and method for efficiently increasing the signal-to-noise ratio of a biometric sampling system by implementing differential-sampling in successive differential-sampling operations and processing the output of the successive differential-sampling operations to create a biometric image. In some cases, the biometric image may be further noise-reduced by subtracting foreground-off and background-off data.

Abstract: A system may include a fingerprint sensor system and a control system. The system may be configured to transmit an ultrasonic wave including a first frequency. The control system may be configured to obtain dermis layer image data from a target object based on reflected portions of the ultrasonic waves received by the fingerprint sensor system. The dermis layer image data may correspond to ultrasonic waves received from the target object within a time interval corresponding with the dermis layer. The reflected portions of the ultrasonic wave corresponding to the dermis layer image data may include ultrasonic waves at a second frequency that is an integer multiple of the first frequency. The control system may be configured to determine whether a magnitude of the ultrasonic waves at the second frequency exceeds a harmonic threshold and, if the magnitude exceeds the harmonic threshold, the control system may perform an authentication process.

Abstract: Techniques describe structures and methods for generating larger output signals and improving image quality of ultrasonic sensors by inclusion of an acoustic cavity in the sensor stack. In some embodiments, an ultrasonic sensor unit may be tuned during manufacturing or during a provisioning phase to work with different thicknesses and materials. In some embodiments, a standing wave signal may be generated using an acoustic cavity in the ultrasonic sensor unit for capturing an ultrasonic image of an object placed on a sensor surface. In some implementations, the ultrasonic sensor may include an ultrasonic transmitter, a piezoelectric receiver, a thin film transistor (TFT) layer and a TFT substrate positioned between the transmitter and the receiver, one or more adhesive layers, and optional cover materials and coatings. The thickness, density and speed of sound of the sensor materials and associated adhesive attachment layers may be used to attain the desired acoustic cavity and improved performance.

Abstract: Systems, methods and apparatus for configuring a fingerprint sensor to operate in a capacitive sensing mode and an ultrasonic sensing mode are disclosed. A fingerprint sensor may be configured to operate in a capacitive sensing mode by driving a sensing electrode using a controller. In some implementations, an object positioned on or near the sensing electrode may be detected using the fingerprint sensor in the capacitive sensing mode, and the controller can drive electrodes of the fingerprint sensor differently to configure the fingerprint sensor to operate in an ultrasonic sensing mode. In some implementations, an applications processor may be instructed to authenticate a fingerprint of the object from image data obtained when the fingerprint sensor is operating in the ultrasonic sensing mode. In some implementations, a display of a mobile device containing the fingerprint sensor may be unlocked, or the mobile device may be woken up when the fingerprint is authenticated.

Abstract: Systems, methods and apparatus for configuring a fingerprint sensor to operate in a capacitive sensing mode and an ultrasonic sensing mode are disclosed. A fingerprint sensor may be configured to operate in a capacitive sensing mode by driving a sensing electrode using a controller. In some implementations, an object positioned on or near the sensing electrode may be detected using the fingerprint sensor in the capacitive sensing mode, and the controller can drive electrodes of the fingerprint sensor differently to configure the fingerprint sensor to operate in an ultrasonic sensing mode. In some implementations, an applications processor may be instructed to authenticate a fingerprint of the object from image data obtained when the fingerprint sensor is operating in the ultrasonic sensing mode. In some implementations, a display of a mobile device containing the fingerprint sensor may be unlocked, or the mobile device may be woken up when the fingerprint is authenticated.

Abstract: An apparatus 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 that is 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.

Abstract: An apparatus 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 that is 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.

Abstract: Disclosed herein are techniques for generating an image of a target object using a sensor. The sensor includes a substrate and a single transceiver. The transceiver includes a first electrode, a second electrode, and a layer of electrical material positioned between the two electrodes. The transceiver also includes a control unit configured to switch the transceiver into a transmit mode or a receive mode. The transceiver further includes a receiving circuit configured to receive, store, and output a detection signal caused by an interaction between the sensor and the target object. The second electrode, the control unit, and the receiving circuit can be formed on the substrate.

Abstract: Methods, systems and storage media are described, each of which may be used to generate an image of an object using ultrasonic plane waves. For example, the generated image may be of a target object positioned on a platen surface. The image may be derived from corrected output signals obtained from a plurality of selected sensor pixels. The corrected output signals may adjust for diffraction of reflected ultrasonic plane waves from a target object positioned on the platen surface. The target object may be a finger or a tip of a stylus.

Abstract: A system may include a fingerprint sensor system and a control system. The system may be configured to transmit an ultrasonic wave including a first frequency. The control system may be configured to obtain dermis layer image data from a target object based on reflected portions of the ultrasonic waves received by the fingerprint sensor system. The dermis layer image data may correspond to ultrasonic waves received from the target object within a time interval corresponding with the dermis layer. The reflected portions of the ultrasonic wave corresponding to the dermis layer image data may include ultrasonic waves at a second frequency that is an integer multiple of the first frequency. The control system may be configured to determine whether a magnitude of the ultrasonic waves at the second frequency exceeds a harmonic threshold and, if the magnitude exceeds the harmonic threshold, the control system may perform an authentication process.

Abstract: Embodiments of an ultrasonic button and methods for using the ultrasonic button are disclosed. In one embodiment, an ultrasonic button may include an ultrasonic transmitter configured to transmit an ultrasonic wave, a piezoelectric receiver layer configured to receive a reflected wave of the ultrasonic wave, a platen layer configured to protect the ultrasonic transmitter and the piezoelectric receiver layer, a first matching layer configured to match an acoustic impedance of the platen layer with an acoustic impedance of ridges of a finger, and an ultrasonic sensor array configured to detect the finger using the reflected wave.

Abstract: Systems, methods and apparatus for configuring a fingerprint sensor to operate in a capacitive sensing mode and an ultrasonic sensing mode are disclosed. A fingerprint sensor may be configured to operate in a capacitive sensing mode by driving a sensing electrode using a controller. In some implementations, an object positioned on or near the sensing electrode may be detected using the fingerprint sensor in the capacitive sensing mode, and the controller can drive electrodes of the fingerprint sensor differently to configure the fingerprint sensor to operate in an ultrasonic sensing mode. In some implementations, an applications processor may be instructed to authenticate a fingerprint of the object from image data obtained when the fingerprint sensor is operating in the ultrasonic sensing mode. In some implementations, a display of a mobile device containing the fingerprint sensor may be unlocked, or the mobile device may be woken up when the fingerprint is authenticated.

Abstract: Disclosed herein are techniques for generating an image of a target object using a sensor. The sensor includes a substrate and a single transceiver. The transceiver includes a first electrode, a second electrode, and a layer of electrical material positioned between the two electrodes. The transceiver also includes a control unit configured to switch the transceiver into a transmit mode or a receive mode. The transceiver further includes a receiving circuit configured to receive, store, and output a detection signal caused by an interaction between the sensor and the target object. The second electrode, the control unit, and the receiving circuit can be formed on the substrate.

Abstract: Techniques describe structures and methods for generating larger output signals and improving image quality of ultrasonic sensors by inclusion of an acoustic cavity in the sensor stack. In some embodiments, an ultrasonic sensor unit may be tuned during manufacturing or during a provisioning phase to work with different thicknesses and materials. In some embodiments, a standing wave signal may be generated using an acoustic cavity in the ultrasonic sensor unit for capturing an ultrasonic image of an object placed on a sensor surface. In some implementations, the ultrasonic sensor may include an ultrasonic transmitter, a piezoelectric receiver, a thin film transistor (TFT) layer and a TFT substrate positioned between the transmitter and the receiver, one or more adhesive layers, and optional cover materials and coatings. The thickness, density and speed of sound of the sensor materials and associated adhesive attachment layers may be used to attain the desired acoustic cavity and improved performance.

Abstract: This disclosure provides some implementations of systems, methods and apparatus associated with a drive scheme for ultrasonic transducer pixel readout. In some implementations, a piezoelectric ultrasonic transducer has a first electrode, a second electrode, and a piezoelectric layer disposed between the first and second electrodes. The second electrode is coupled with a sampling node. A sampling diode has an input and an output. The input is coupled to receive a diode bias signal. The output is coupled with the sampling node. Controller circuitry is configured to control the diode bias signal to at least partially drive a voltage at the sampling node. Read circuitry is coupled with the sampling node to read the voltage.