Abstract: To make it possible to sustain a low power consumption for the entire driver in a driver of a piezoelectric actuator, by reducing the number of components and switching the piezoelectric actuator at a high speed. Common resistors Ra and Rb for current limitation are interposed at some midpoint of the feeder lines 19 and 21. Phototransistors Q1 to Q8 are connected to the power source side of the common resistors Ra and Rb of the feeder lines 19 and 21. Piezoelectric actuators 1a to 1h are connected to terminals Sa and Sb of the common resistors Ra and Rb on the side opposite to the power supply section, and to the joints of the phototransistors Q1 to Q8. Light emitting diodes D1 to D8 are disposed in proximity to the phototransistors Q1 to Q8, and the light emitting diodes D1 to D8 are switched and conducted at a switching control section 25.

Abstract: Disclosed is a stacked piezoelectric actuator displaceable by bending comprising a plurality of piezoelectric ceramic layers stacked on one surface of a core material, and a plurality of piezoelectric ceramic layers stacked on the other surface thereof, said piezoelectric ceramic layers stacked on both surfaces being successively increased in piezoelectric constant d.sub.31 inner layers to outer layers. The piezoelectric coefficient d.sub.31 is derived from the following equation (2): ##EQU1## wherein k is the electromechanical coupling coefficient, the length vibration of a rectangular plate is taken as k.sub.31, and the unit of the piezoelectric coefficient d.sub.31 is C/N (m/V). The piezoelectric coefficient d.sub.33 in the longitudinal vibration of a column determined by the following equation (3) is a value for the whole stacked layers, and in the present invention, it is necessary that the piezoelectric coefficient d.sub.

Abstract: Disclosed is a knitting needle driving mechanism of a jacquard knitting machine for driving knitting needles by using piezo-electric elements in which a rear end portion of a piezo-electric body is movably supported in a groove of a supporting body or a housing, a front end portion of the piezo-electric body is movably connected to a rear end portion of a finger which is arranged so as to be aligned with the piezo-electric body and supported at the rear end portion thereof by the supporting body or the housing, and an intermediate portion between the front end portion and the rear end portion of the piezo-electric body is inserted into a rotatable member rotatably mounted on the supporting body or the housing. This knitting needle driving mechanism is small in size, high in response speed and prolonged in lifetime.