There are provided a laminated piezoelectric element in which a stress applied to an interface between a cover layer and a stacked body is reduced, and an injection device and a fuel injection system provided with the laminated piezoelectric element. A laminated piezoelectric element includes a stacked body in which piezoelectric layers and internal electrode layers are alternately laminated; and a cover layer disposed so as to surround a side face of the stacked body, and the cover layer has a two-layer structure with an annular boundary when viewed in a section perpendicular to a stacking direction of the stacked body.

The application describes MEMS transducer structures comprising a membrane structure having a flexible membrane layer and at least one electrode layer. The electrode layer is spaced from the flexible membrane layer such that at least one air volume extends between the material of the electrode layer and the membrane layer. The electrode layer is supported relative to the flexible membrane by means of a support structure which extends between the first electrode layer and the flexible membrane layer.

An acoustic resonator includes a wafer and a first phononic crystal disposed on the wafer to define an acoustic waveguide so as to propagate an acoustic wave along a propagation direction. The first phononic crystal includes a first two-dimensional (2D) array of metal stripes having a first period on the propagation direction. The apparatus also includes a second phononic crystal and a third phononic crystal disposed on two sides of the first phononic crystal and having a different period from the first period. The second phononic crystal and the wafer define a first reflector to reflect the acoustic wave. The third phononic crystal and the wafer define a second reflector to reflect the acoustic wave.

A piezoelectric element including a piezoelectric layer having a perovskite structure including lead, zirconium, and titanium, and an electrode provided on the piezoelectric layer is provided. In the piezoelectric layer, in a range of 50 nm or smaller from an interface between the piezoelectric layer and the electrode in a thickness direction, a ratio c/a of a lattice spacing a in a direction perpendicular to the thickness direction and a lattice spacing c in the thickness direction satisfies 0.986≤c/a≤1.014.

There is provided a liquid discharge head including a piezoelectric body having a plurality of individual electrodes and a first common electrode, and a plurality of conductor layers. The plurality of individual electrodes have first to fourth individual electrode arrays, and the first common electrode has first and second extending portions, a plurality of first projecting portions, and a plurality of second projecting portions. Each of the first projecting portions overlaps partially with one of the plurality of individual electrodes forming the second individual electrode array along the stacking direction, and each of the second projecting portions overlaps partially with one of the plurality of individual electrodes forming the third individual electrode array along the stacking direction. The plurality of conductor layers are formed between the plurality of first projecting portions and the plurality of second projecting portions, without contacting the first common electrode and without contacting each other.

A virtual resistive load feedback circuit for driving a piezoelectric actuator is provided that accounts for a hysteresis error and drift within the movement of the actuator. The circuit may include a voltage divider and charge divider. A voltage monitor signal corresponding to a voltage of a driver signal and a current monitor signal corresponding to a current provided to the amplifier are combined by an operational amplifier and include electrical characteristics of the actuator such that the circuit approximates a virtual load across the actuator. A feedback portion of the operational amplifier may include a resistor and capacitor connected in parallel to provide the voltage and charge divide functions. The use of the virtual resistive circuit allows for the piezoelectric actuator to be ground referenced, with no external components connected directly to the actuator while gaining the feedback effect to counter the hysteresis and drifts errors of the actuator.

A vibration element includes: a base; a first arm continuous with the base; a second arm that is continuous with the base and is adjacent to the first arm; a first electrode disposed on the first arm, the second arm, and the base; a first piezoelectric layer that has a first polarity and that is disposed on the first electrode on the first arm; a second piezoelectric layer that has a second polarity different from the first polarity and that is disposed on the first electrode on the second arm; an insulating layer disposed on the first electrode on the base; and a second electrode disposed on the first piezoelectric layer, the second piezoelectric layer, and the insulating layer.

An actuating device includes an actuator and a stationary portion. The actuator has at least one driving portion. The stationary portion is provided at an arbitrary position along the actuator such that the driving portion forms a first driving portion and a second driving portion. The first driving portion and the second driving portion can be provided with the same actuating ability or with different actuating abilities respectively by adjusting the position of the stationary portion.

An air motor is provided for converting electrical energy into kinetic energy, and using the kinetic energy to generate a specified air pressure and a specified airflow rate. The air motor comprises plural air motor units, each of which includes a main body and a piezoelectric actuator. The piezoelectric actuator is disposed within the main body. When the piezoelectric actuator is enabled, the air within the main body is controlled and driven to flow. The air motor can be used to replace various types of motors, compressors or engines.

A piezoelectric thin film 3 contains a metal oxide, the metal oxide contains bismuth, potassium, titanium, iron and element M, the element M is at least one of magnesium and nickel, at least a part of the metal oxide is a crystal having a perovskite structure, and a (001) plane, a (110) plane or a (111) plane of the crystal is oriented in a normal direction dn of the surface of the piezoelectric thin film 3.