Abstract: A system for providing closed-loop control of a linear resonant actuator using Back Electromotive Force (EMF) and inertial compensation is disclosed. In an embodiment, one or more inertial sensors are used to estimate low frequency motion of a haptic engine moving mass and compensate for the motion using a feedforward model, thus providing a more robust closed-loop control system for controlling the moving mass when subjected to low frequency disturbances by a user, for example, shaking or swinging the device.

Abstract: A display system may display image frames. The system may include a scanning mirror and an array of staggered light emitting elements. The light emitting elements may emit image light and collimating optics may direct the light at the scanning mirror, which reflects the image light while rotating about an axis. Control circuitry may selectively activate the light emitting elements across tangential and sagittal axes of the image frame while controlling the scanning mirror to scan across the sagittal axis.

Abstract: A display system may display image frames. The system may include multiple sets of laser dies. Each set of laser dies may emit a respective set of beams of light to a photonic integrated circuit. Each set of beams may include light in at least three wavelength ranges that include visible and/or infrared wavelengths. Channels in the photonic integrated circuit may receive the sets of beams with a first pitch and may emit the set of beams with a second pitch that is finer than the first pitch and at a given angular separation to tangential and sagittal axis scanning mirrors.

Abstract: Micromachined ultrasonic transducer (MUT) arrays capable of multiple resonant modes and techniques for operating them are described, for example to achieve both high frequency and low frequency operation in a same device. In embodiments, various sizes of piezoelectric membranes are fabricated for tuning resonance frequency across the membranes. The variously sized piezoelectric membranes are gradually transitioned across a length of the substrate to mitigate destructive interference between membranes oscillating in different modes and frequencies.

Abstract: A plurality of transducer elements are formed. For each of the plurality of transducer elements, an electrode of the transducer element is formed on a first side of a support layer. A piezoelectric element of the transducer element is formed on the first side of the support layer. An interconnect of the transducer element is formed in the support layer. The support layer is thinned to expose a second side of the support layer. The interconnects of the plurality of transducer elements extend between the first side and the second side of the support layer. The second side of the support layer is bonded to a flexible layer with an adhesive material. Conductive fillers are disposed in the adhesive material. The interconnects of the plurality of transducer elements are each electrically coupled via the conductive fillers to the corresponding interconnect extending through the flexible layer.

Abstract: An integrated circuit (IC) chip including an array of asymmetrically distributed magnetic field sensing elements. Additionally, an integrated circuit (IC) chip includes a substrate, a sensing coil supported by the substrate and enclosing a portion of substrate, and a Hall effect sensor supported by the portion of the substrate enclosed by the sensing coil.

Abstract: An electronic device such as a pair of headphones may be provided with ear cups having speakers for playing audio to a user. Capacitive sensor electrodes may be used in capturing capacitive sensor ear images that are processed by a machine learning classifier to determine whether the headphones are being worn in a reversed or unreversed orientation. The capacitive sensor electrodes may include grill electrodes that overlap at least part of a speaker grill, cushion electrodes that make capacitive sensor measurements through ring-shaped ear cup cushions that surround the speaker grills, and ring electrodes. The ring electrodes may be formed from metal traces on a flexible printed circuit. The flexible printed circuit may include a portion that wraps around each speaker grill and that is surrounded by a corresponding one of the cushions.

Abstract: An integrated circuit (IC) chip including an array of asymmetrically distributed magnetic field sensing elements. Additionally, an integrated circuit (IC) chip includes a substrate, a sensing coil supported by the substrate and enclosing a portion of substrate, and a Hall effect sensor supported by the portion of the substrate enclosed by the sensing coil.

Abstract: An electronic device such as a pair of headphones may be provided with ear cups having speakers for playing audio to a user. Capacitive sensor electrodes may be used in capturing capacitive sensor ear images that are processed by a machine learning classifier to determine whether the headphones are being worn in a reversed or unreversed orientation. The capacitive sensor electrodes may include grill electrodes that overlap at least part of a speaker grill, cushion electrodes that make capacitive sensor measurements through ring-shaped ear cup cushions that surround the speaker grills, and ring electrodes. The ring electrodes may be formed from metal traces on a flexible printed circuit. The flexible printed circuit may include a portion that wraps around each speaker grill and that is surrounded by a corresponding one of the cushions.

Abstract: A haptic actuator may include a housing, coils carried within the housing, and a field member moveable within the housing between the coils and including at least one permanent magnet. A controller may be coupled to the coils and configured to sense a respective back electromotive force (EMF) value of each of the coils and determine a position of the field member in dimensions based upon the back EMF values and motor constant values.

Abstract: In an embodiment of a system for closed-loop control of a linear resonant actuator, a system processor coupled to a magnetic field sensor is configured to: receive a magnetic field sensor signal from a channel coupling a magnetic field sensor and the system processor; receive measurements of actuator current and actuator voltage from drive electronics; receive a temperature signal from a linear resonant actuator, the temperature signal indicating a temperature of the magnetic field sensor; calculate a first estimate of mass position using the magnetic field sensor signal, actuator current and a magnetic model; calculate an estimate of coil resistance based on the temperature signal, the actuator current, the actuator voltage and a thermal model; and calculate a second estimate of mass position and an estimate of mass velocity based on the first estimate of mass position, the actuator current, the actuator voltage and the estimated coil resistance.

Abstract: A haptic actuator may include a housing having a top and a bottom. At least one of the top and the bottom may have a shape defining an internal recess therein. The haptic actuator may include a coil carried within the internal recess, and a field member having opposing first and second sides and that includes at least one permanent magnet adjacent the coil. The haptic actuator may also include a respective flexure bearing mounting each of the first and second sides of the field member to be reciprocally movable within the housing responsive to the coil.

Abstract: A system for providing closed-loop control of a linear resonant actuator using Back Electromotive Force (EMF) and inertial compensation is disclosed. In an embodiment, one or more inertial sensors are used to estimate low frequency motion of a haptic engine moving mass and compensate for the motion using a feedforward model, thus providing a more robust closed-loop control system for controlling the moving mass when subjected to low frequency disturbances by a user, for example, shaking or swinging the device.

Abstract: A haptic actuator may include a housing, coils carried within the housing, and a field member moveable within the housing between the coils and including at least one permanent magnet. A controller may be coupled to the coils and configured to sense a respective back electromotive force (EMF) value of each of the coils and determine a position of the field member in dimensions based upon the back EMF values and motor constant values.

Abstract: A method of tuning a haptic actuator that includes a housing having an initial ferromagnetic mass, at least one coil carried by the housing, and a field member movable within the housing responsive to the at least one coil, wherein the haptic actuator operative as a resonator and has an initial quality (Q) factor, may include measuring the initial Q factor of the haptic actuator. The method may include determining a desired ferromagnetic mass for the housing to tune the initial Q factor to a desired Q factor. The method may also include changing the initial ferromagnetic mass of the housing to the desired ferromagnetic mass. Another embodiment changes the ferromagnetic mass of the field member.

Abstract: A haptic actuator may include a housing, at least one coil carried by the housing, and a field member having opposing first and second sides. The haptic actuator may also include a respective flexure bearing mounting each of the first and second sides of the field member to be reciprocally movable within the housing responsive to the at least one coil. Each flexure bearing may include a first anchor member coupled to an adjacent portion of the housing, a second anchor member coupled to an adjacent side of the field member, and a first flexible arm coupling the first and second anchor members together and having at least one bend therein.

Abstract: A method is directed to tuning a haptic actuator that includes a housing having a ferromagnetic mass, a coil carried by the housing, and a field member movable within the housing responsive to the coil. The haptic actuator is operative as a resonator and has an initial quality (Q) factor. The method may include determining whether the initial Q factor is within a desired Q factor range, and when the initial Q factor is not within the desired Q factor range, performing ferromagnetic mass change iterations until an updated Q factor is within the desired Q factor range. Each ferromagnetic mass change iteration may include changing the ferromagnetic mass of the housing, determining the updated Q factor based upon changing the ferromagnetic mass of the housing, and determining whether the updated Q factor is within the desired Q factor range. Another embodiment changes the ferromagnetic mass of the field member.

Abstract: In an embodiment of a system for closed-loop control of a linear resonant actuator, a system processor coupled to a magnetic field sensor is configured to: receive a magnetic field sensor signal from a channel coupling a magnetic field sensor and the system processor; receive measurements of actuator current and actuator voltage from drive electronics; receive a temperature signal from a linear resonant actuator, the temperature signal indicating a temperature of the magnetic field sensor; calculate a first estimate of mass position using the magnetic field sensor signal, actuator current and a magnetic model; calculate an estimate of coil resistance based on the temperature signal, the actuator current, the actuator voltage and a thermal model; and calculate a second estimate of mass position and an estimate of mass velocity based on the first estimate of mass position, the actuator current, the actuator voltage and the estimated coil resistance.

Abstract: In an embodiment, a transducer device has a flexible substrate and a plurality of tiles coupled to the substrate. The tiles each include a plurality of piezoelectric transducer elements and a base adjoining and supporting the plurality of piezoelectric transducer elements. The substrate has disposed therein or thereon signal lines to serve as a backplane for communication to, from and/or among integrated circuitry of the tiles. In another embodiment, the integrated circuitry of the tiles are each pre-programmed to implement any of a respective plurality of operational modes. Signals exchanged with the tiles via the flexible substrate facilitate operation of the transducer device to provide a phased array of transducer elements.

Abstract: An integrated circuit (IC) chip for driving a mass of a linear resonant actuator (LRA) using low-latency closed-loop control is described. The IC chip includes class-D amplifier circuitry configured to provide to coils of the LRA, a driving signal, which has a pulse-width modulation configured to control a position of the mass as a function of time. The driving signal has a frequency in a range of 10-100 kH, and the pulse-width modulation has a bandwidth smaller than 1 kHz. The IC chip also includes class-D controller circuitry configured to process (i) a position-monitoring signal, which (a) is received from position sensors of the LRA and (b) corresponds to the position of the mass, and (ii) a drive-monitoring signal, which relates to the driving signal, to obtain a digital driving signal. The class-D amplifier circuit is configured to amplify the digital driving signal to obtain the analog driving signal.