Abstract: A device comprises a processor coupled with an ultrasonic transducer coupled which is configured to emit an ultrasonic pulse and receive returned signals received after a ringdown period of the transducer and corresponding to the emitted ultrasonic pulse. The processor is configured to evaluate the returned signals to find a candidate echo, from an object located in a ringdown blind spot area, in a time window between one and two times the ringdown period; locate multiple echoes from the object of higher order than the candidate echo; validate the candidate echo as at least a secondary echo associated of the object; and determine, based on analysis of the returned signals, an estimated distance from the transducer to the object in the ringdown blind spot area, wherein the ringdown blind spot area is located between the transducer and a closest distance at which objects can be sensed by the transducer.

Abstract: A piezoelectric micromachined ultrasound transducer (PMUT) is disclosed. The device consists of a flexible membrane that is connected to a rigid substrate via flexures. The flexures are defined by slots etched through the perimeter of the membrane. These features release the stress present on the structural layers of the membrane, making it less sensitive to residual stress. The flexures are designed to act as torsion springs so that the membrane's vibration mode shape is highly curved in the piezoelectric actuation area, thereby increasing the electromechanical coupling.

Abstract: A device comprises a processor coupled with an ultrasonic transducer which is configured to emit an ultrasonic pulse and receive corresponding returned signals associated with a distance range of interest in a field of view of the ultrasonic transducer. The processor is configured to: remove a low frequency component from the returned signals to achieve modified returned signals; calculate, from the modified returned signals, a variation in amplitude; determine a quantification of the variation in amplitude for a first subset of the modified returned signals associated with a first subrange of the distance range of interest; employ the quantification to correct for changes in the first subset to achieve first normalized sensor data for the first subrange, where the first normalized sensor data is sensitive to occurrence of change over time in the first subrange; and detect a moving object in the first subrange using the first normalized sensor data.

Abstract: An ultrasonic transmitter system includes a digital controller, bandpass pulse-width modulator (BP-PWM) unit, a digital to analog converter (DAC), and an ultrasound transducer. The controller generates pulse width and phase reference signals. The BP-PWM configured receives these signals generates a pulse width modulation (PWM) output characterized by a pulse width and a phase based on the pulse width and phase reference signals. The DAC) receives the PWM output from the BP-PWM unit and generates an output characterized by the pulse width and phase. The ultrasonic transducer receives the output from the DAC and generates an output sound pressure in response to the output from the DAC. An amplitude of the RMS sound pressure depends on the pulse width of the output from the DAC.

Abstract: A device comprises a processor coupled with an ultrasonic transducer coupled which is configured to emit an ultrasonic pulse and receive returned signals received after a ringdown period of the transducer and corresponding to the emitted ultrasonic pulse. The processor is configured to evaluate the returned signals to find a candidate echo, from an object located in a ringdown blind spot area, in a time window between one and two times the ringdown period; locate multiple echoes from the object of higher order than the candidate echo; validate the candidate echo as at least a secondary echo associated of the object; and determine, based on analysis of the returned signals, an estimated distance from the transducer to the object in the ringdown blind spot area, wherein the ringdown blind spot area is located between the transducer and a closest distance at which objects can be sensed by the transducer.

Abstract: A robotic cleaning appliance includes a housing, surface treatment item, surface type detection sensor, and processor. The sensor emits sonic signals toward a surface being traversed and receives corresponding returned signals from the surface. The returned signals are used for surface type detection and include directly reflected primary returned signals and multi-path reflected secondary returned signals which return at a later time than the primary returned signals. The processor selects a window of time after transmission of a sonic signal such that the returned signals in the window comprise at least a portion of the secondary returned signals, wherein the window is related to round trip time-of-flight of the returned signals; processes the returned signals falling in the window to achieve a reflectivity metric; compares the reflectivity metric to a stored value; and based on the comparison, determines which surface type of a plurality of surface types has been detected.

Abstract: A tracking method includes displaying visual content on a screen of a head mounted display (HMD). One or more base stations may be stationary with respect to the screen while the visual content is being displayed. In contrast, one or more objects may move with respect to the screen while the visual content is being displayed. Time-difference-of-arrival (TDoA) and/or time-of-flight (ToF) may be measured for one or more ultrasonic pulses transmitted from the base station, one or more objects, or HMD. Position and orientation of the objects and HMD may be calculated based on the TDoA and ToF. Different frequencies of pulses may be used to locate the HMD and the objects. An electromagnetic synchronization signal from the HMD and/or base station may be used to measure TDoA. Position and orientation measurements may be fused with outputs from IMUS (inertial measurement units) to reduce jitter.

Abstract: A piezoelectric micromachined ultrasonic transducer (pMUT) device may include a piezoelectric membrane transducer designed to have lower sensitivity to residual stress and reduced sensitivity to geometric variations arising from the backside etching process used to release the membrane. These designs allow some of its key feature to be adjusted to achieve desired characteristics, such as pressure sensitivity, natural frequency, stress sensitivity, and bandwidth.

Abstract: An ultrasound transducer may be driven by a driver circuit having one or more charge pumps and a multi-level inverter. The one or more charge pumps are configured to drive the ultrasound transducer only during output transitions of the inverter.

Abstract: Time of flight between two or more ultrasonic transceivers is measured using known delays between receiving a trigger and sending an ultrasonic pulse in reply. A receive time is measured from a beginning of a receive phase in which the pulse is detected until receipt of an ultrasonic reply pulse. A trip time is determined from a sum of the receive time and a difference between a known first reference period for a transceiver that sends the trigger pulse and a second know reference period for a second transceiver that sends the reply pulse. The second reference period corresponds to a delay between when the second transceiver receives the initial or subsequent trigger pulse from the first transceiver and when the second transceiver sends the reply pulse.

Abstract: A tracking method is disclosed. The method may include displaying visual content on a screen. A base station may be stationary with respect to the screen while the visual content is being displayed. In contrast, one or more objects may move with respect to the screen while the visual content is being displayed. The one or more objects may be tracked so that the movement thereof may be used to alter the visual content. Such tracking may involve the base station and the one or more objects sending and/or receiving one or more ultrasonic pulses. Time-difference-of-arrival and/or time-of-flight of the one or more ultrasonic pulses may then be used to estimate a relative location and/or a relative orientation of the one or more objects with respect to the base station in three dimensional space.

Abstract: An apparatus comprises an ultrasonic transducer having a first and second electrode and switches which configured to selectively connect the first and second electrodes to a transmit voltage source or to a receive amplifier. The switches are configured to selectively connect a first input of the amplifier to the first electrode of the transducer and to selectively connect a second input of the amplifier to the second electrode of the transducer. The switches are also configured to selectively connect the voltage source to the first and second electrodes of the transducer. The transducer may include a piezoelectric layer attached to and sandwiched between the first electrode and the second electrode, and a flexible membrane attached to the first electrode. The piezoelectric layer may be patterned to form an annular ring at the outer diameter of the flexible membrane.

Abstract: An ultrasonic input includes two or more ultrasonic transceiver units having transducers separated from each other by a predetermined spacing and a processor coupled to the transceiver units. In some implementations one unit transmits while two receive and in other implementations one unit transmits and receives while the other just receives. The transmitter sends an ultrasonic pulse and first and second receivers receive echoes of the ultrasonic pulse from an object. The processor and/or transceiver units use first and second receive signals to determine first and second time-of-flight (ToF) measurements corresponding to times between transmitting an ultrasonic pulse and receiving an echo of the ultrasonic pulse.

Abstract: An ultrasonic transceiver system includes a transmitter block, a receiver block, a state machine, a computer unit. The transmitter block contains circuitry configured to drive an ultrasound transducer. The receiver block contains circuitry configured to receive signals from the ultrasound transducer and convert the signals into digital data. The state machine is coupled to the transmitter and receiver blocks and contains circuitry configured to act as a controller for those blocks. The computing unit is coupled to the transmitter block, the receiver block, and the state machine and is configured to drive the transmitter block and process data received from the receiver block by executing instructions of a program. The program memory is coupled to the computing unit and is configured to store the program. The computing unit is configured to be reprogrammed with one or more additional programs stored in the program memory.

Abstract: An ultrasonic transceiver can detect the presence of nearby moving objects while rejecting signals from stationary targets and from transmitter signal feedthrough. Data corresponding to received ultrasound signals are stored in a digital memory. For each sample in a measurement, a difference is calculated between corresponding samples in the stored data corresponding to received signals for current and previous measurements to estimate a time of flight to a moving object.

Abstract: A system and method use an array of ultrasonic transducers to emit and receive sound in a phased array fashion by using acoustic waveguides to achieve a desired acoustic radiation and reception pattern. A chip package attached to an acoustic transducer array includes acoustic waveguides coupled to acoustic ports. Each waveguide is coupled between a corresponding acoustic transducer and a corresponding acoustic port. A spacing of a pair of acoustic ports is different than a spacing of a corresponding pair of acoustic transducers.

Abstract: A piezoelectric micromachined ultrasound transducer (PMUT) is disclosed. The PMUT consists of a flexural membrane that is piezoelectrically actuated. These membranes are formed on a first substrate that is bonded to a second substrate. The two substrates are separated by an air gap to allow the PMUT to vibrate. Several methods for joining the two substrates are described.

Abstract: A transducer includes first and second piezoelectric layers made of corresponding different first and second piezoelectric materials and three or more electrodes, implemented in two or more conductive electrode layers. The first piezoelectric layer is sandwiched between a first pair of electrodes and the second piezoelectric layer is sandwiched between a second pair of electrodes. The first and second pairs of electrodes contain no more than one electrode that is common to both pairs.

Abstract: A tracking method is disclosed. The method may include displaying visual content on a screen. A base station may be stationary with respect to the screen while the visual content is being displayed. In contrast, one or more objects may move with respect to the screen while the visual content is being displayed. The one or more objects may be tracked so that the movement thereof may be used to alter the visual content. Such tracking may involve the base station and the one or more objects sending and/or receiving one or more ultrasonic pulses. Time-difference-of-arrival and/or time-of-flight of the one or more ultrasonic pulses may then be used to estimate a relative location and/or a relative orientation of the one or more objects with respect to the base station in three dimensional space.

Abstract: A piezoelectric micromachined ultrasound transducer (PMUT) is disclosed. The device consists of a flexible membrane that is connected to a rigid substrate via flexures. The flexures are defined by slots etched through the perimeter of the membrane. These features release the stress present on the structural layers of the membrane, making it less sensitive to residual stress. The flexures are designed to act as torsion springs so that the membrane's vibration mode shape is highly curved in the piezoelectric actuation area, thereby increasing the electromechanical coupling.