A piezoelectric drive device includes: a vibrating body having a first surface and a second surface provided with a recessed portion; and a piezoelectric element provided on the first surface. The recessed portion and the piezoelectric element have an overlap region when viewed in a normal direction of the second surface.

A piezoelectric driving device includes a substrate, a first insulating film disposed on the substrate, a piezoelectric element for driving disposed on the first insulating film and configured to vibrate the substrate, a piezoelectric element for detection configured to detect the vibration of the substrate, a wire for driving electrically connected to the piezoelectric element for driving, a wire for detection electrically connected to the piezoelectric element for detection, and a lower layer wire disposed between the first insulating film and the substrate and set to fixed potential. At least one of the wire for driving and the wire for detection overlaps at least a part of the lower layer wire.

Embodiments of the disclosure are generally directed to systems and methods for switchable electroactive devices for head-mounted displays (HMDs). In particular, a method may include (1) applying an electric field to an electroactive element of an electroactive device via electrodes of the electroactive device that are electrically coupled to the electroactive element to compress the electroactive element, which comprises a polymer material defining nanovoids, such that an average size of the nanovoids is decreased and a density of the nanovoids is increased in the electroactive element, wherein the electroactive device is positioned at a distance from a user's eye, and (2) emitting image light from an emissive device positioned such that at least a portion of the image light is incident on a surface of the electroactive device facing the user's eye.

A vehicle sensor assembly includes an optical sensor surface, at least two transducers arranged to input energy into the optical surface to produce an energy wave through the optical sensor surface and sense an attribute of an energy wave within the optical sensor surface. A controller arranged to drive the at least two transducers to input energy into the optical surface to produce an energy wave within the optical sensor surface to dislodge debris from the optical sensor surface.

An example device includes a nanovoided polymer element, which may be located at least in part between the electrodes. In some examples, the nanovoided polymer element may include anisotropic voids, including a gas, and separated from each other by polymer walls. The device may be an electroactive device, such as an actuator having a response time for a transition between actuation states. The gas may have a characteristic diffusion time (e.g., to diffuse half the mean wall thickness through the polymer walls) that is less than the response time. The nanovoids may be sufficiently small (e.g., below 1 micron in diameter or an analogous dimension), and/or the polymer walls may be sufficiently thin, such that the gas interchange between gas in the voids and gas absorbed by the polymer walls may occur faster than the response time, and in some examples, effectively instantaneously.

Example methods include depositing a precursor layer onto a substrate where the precursor layer includes droplets comprising a polymerizable material, inducing a phase inversion in the precursor layer to obtain a modified precursor layer including droplets of a non-polymerizable liquid within a polymerizable liquid mixture, and polymerizing the polymerizable liquid mixture to obtain a nanovoided polymer element. Examples include devices fabricated using nanovoided polymer elements fabricated using such methods, including electroactive devices such as actuators and sensors.

An optical element includes a nanovoided polymer layer having a first refractive index in an unactuated state and a second refractive index different than the first refractive index in an actuated state. Compression or expansion of the nanovoided polymer layer, for instance, can be used to reversibly control the size and shape of the nanovoids within the polymer layer and hence tune its refractive index over a range of values, e.g., during operation of the optical element. Various other apparatuses, systems, materials, and methods are also disclosed.

A piezoelectric vibrator has a first frequency region where the phase difference between a pickup signal representing the vibration of the piezoelectric vibrator and a drive signal that drives the piezoelectric vibrator does not monotonously change in accordance with the frequency of the drive signal and a second frequency region where the phase difference monotonously changes in accordance with the frequency of the drive signal. A method for controlling a piezoelectric driving apparatus including the piezoelectric vibrator controls the frequency of the drive signal in such a way that pickup voltage representing the amplitude of the pickup signal is fixed in the first frequency region and controls the frequency of the drive signal in such a way the pickup voltage is fixed with the phase difference maintained smaller than or equal to a prespecified value in the second frequency region.

A support structure includes a fixed frame portion configured to provide a fixed connection point for the support structure. The support structure also includes a suspended frame portion configured to support the interactive device and configured to oscillate in a direction of motion relative to the fixed frame portion due to a force applied to at least one of the fixed frame portion or the suspended frame portion by an actuator configured to provide a haptic effect to the interactive device. Further, the support structure includes one or more support members coupled between the fixed frame portion and the suspended frame portion. The direction of motion is defined by the one or more support members. The one or more support members provide a restoring force that causes the suspended frame portion to undergo harmonic oscillation in the direction of motion in response to the force applied by the actuator.

A gripping device includes a rotating member having a pinion and rotating about a center axis of the pinion, a drive piezoelectric unit having a vibrating portion that vibrates with expansion and contraction of a piezoelectric material, and a convex portion provided in the vibrating portion, being in contact with the rotating member, and transmitting vibration of the vibrating portion to the rotating member, a rack meshing with the pinion and moving with rotation of the pinion, and a gripping part coupled to the rack, wherein a contact portion in which the convex portion and the rotating member are in contact is located outside of an outer circumference of the pinion in a plan view from a direction of a rotation axis of the rotating member.