A piezoelectric driving device includes a vibrating plate, a first electrode, a piezoelectric layer, a second electrode layer provided above the vibrating plate. An active section is formed in a portion where the first electrode layer, the piezoelectric layer, and the second electrode layer overlap one another. The active section has a longitudinal direction and a latitudinal direction in plan view. At both ends in the latitudinal direction, ends of the first electrode layer are disposed in the same positions as ends of the wiring layer or further on the outer side than the ends, ends of the second electrode layer are disposed in the same positions as the ends of the wiring layer or further on the inner side than the ends, and the ends of the first electrode layer are disposed further on the outer side than the ends of the second electrode layer.

A piezoelectric actuator includes a plurality of piezoelectric elements that generate a driving force to be transmitted to a driven portion; and a power supply portion that supplies power to the plurality of piezoelectric elements. The plurality of piezoelectric elements are electrically connected to the power supply portion in parallel.

A fluid pump (10) for pumping fluids is described. The fluid pump uses actuators like loudspeakers or piezoelectric elements that are arranged in a fluid chamber side by side to each other to generate a fluid flow by driving the actuators with phase shifted signals, so that fluid is sucked into an inlet end of the fluid chamber and pushed out of an outlet end of the fluid chamber.

According to an embodiment, a piezoelectric pump includes a pressure chamber. A groove is provided to a bottom portion of the pressure chamber. The groove includes an inlet and an outlet on a bottom portion of the groove, liquid being caused to flow in the pressure chamber through the inlet and to be discharged from the pressure chamber through the outlet.

An active cooling system and method for using the active cooling system are described. The active cooling system includes a cooling element having a first side and a second side. The first side of the cooling element is distal to a heat-generating structure and in communication with a fluid. The second side of the cooling element is proximal to the heat-generating structure. The cooling element is configured to direct the fluid using a vibrational motion from the first side of the cooling element to the second side such that the fluid moves in a direction that is incident on a surface of the heat-generating structure at a substantially perpendicular angle and then is deflected to move along the surface of the heat-generating structure to extract heat from the heat-generating structure.

A system for cooling a mobile phone and method for using the system are described. The system includes an active piezoelectric cooling system, a controller and an interface. The active piezoelectric cooling system is configured to be disposed in a rear portion of the mobile phone distal from a front screen of the mobile phone. The controller is configured to activate the active piezoelectric cooling system in response to heat generated by heat-generating structures of the mobile phone. The interface is configured to receive power from a mobile phone power source when the active piezoelectric cooling system is activated.

A fluid control device includes a housing. The housing includes a first main plate, a second main plate, and a side plate connecting the first main plate and the second main plate. The housing has a pump chamber defined by the first main plate, the second main plate, and the side plate. The fluid control device also includes a driver, a first hole that extends through the first main plate or the second main plate, and a first recess formed in the first main plate between a center and a circumference or the second main plate between a center and a circumference.

An aircraft assembly having: a first part; a second part, the second part being movably mounted with respect to the first part; an electro-hydraulic actuator coupled between the second part and a first anchor point, the actuator comprising a cylinder defining a bore and a piston and rod assembly slidably mounted within the bore and an active chamber within which an increase in fluid pressure causes the actuator to change during a first phase between first and second extension states to move the second part relative to the first part. The electro-hydraulic actuator further includes a hydraulic fluid supply circuit comprising a piezo-electric pump operable to supply pressurised fluid to the active chamber to change the actuator between first and second extension states.

A voltage driving apparatus for a portable fluid pump comprising a power source arranged to provide a direct current, a DC gain unit electrically connected, in use, to receive a voltage from the power source and output an amplified voltage, and a DC to AC conversion unit arranged, in use, to receive the amplified voltage from the DC gain unit and output a periodic waveform to drive a piezoelectric actuator in the portable fluid pump. The output periodic waveform comprises a first discrete voltage level and a second discrete voltage level. Each period of the waveform comprises the first voltage level for a first length of time and a second voltage level for a second length of time.

A piezoelectric element drive circuit includes a piezoelectric element driven at a predetermined frequency and having a resonant frequency of (2n+1) times the predetermined frequency (n is a predetermined natural number), and a drive voltage generator that has a first output terminal connected to a first terminal of the piezoelectric element and a second output terminal connected to a second terminal of the piezoelectric element. When the piezoelectric element is driven, a waveform of potential difference between the first output terminal and the second output terminal is a step wave which transitions while taking an intermediate potential. A time length for which the potential difference is the intermediate potential is around (t2−t1)/(2n+1) in a period of time from time t.sub.1 at which the potential difference falls to the intermediate potential to time t.sub.2 at which the potential difference falls to the intermediate potential subsequently.