Abstract: An electromechanical actuator has a stack composed of electromechanical elements, and an inactive element intervening in the stack to divide it into two sections. In a wire-dot printing head using the actuator, the stack sections are successively energized to increase a forward stroke of a printing wire for a high speed printing. In another aspect, an electromechanical actuator used in a wire-dot printer has a spring for regulating and braking a rearward stroke of a printing wire or a stopper such that the wire can be prevented from being moved back beyond an initial position. Alternatively, a stopper is incorporated to forcibly stop the wire at the initial position during the rearward stroke thereof. In yet another aspect, an electromechanical actuator has a stack composed of electromechanical elements, and the stack is supported by a block through a leaf spring securely joined therebetween to prevent generation of large stress in the stack.

Abstract: A wire-dot printing head has a housing in which a plurality of actuator assemblies are accommodated to drive a plurality of wire elements. An annular hollow space is formed in a side wall of the housing surrounding the actuator assemblies, whereby noise and vibration produced during operation of the actuator assemblies can be effectively damped due to the formation of the annular hollow space. When an interior of the housing is partially charged with gel-like damping material for damping the noise and vibration, a hollow space is formed in the charged damping material, whereby the increase in the inertial mass of the printing head can be reduced.

Abstract: A piezoelectric printing head includes an annular base frame and a plurality of piezoelectric actuator assemblies mounted on the base frame. Each actuator assembly includes a piezoelectric element having one end rigidly secured to the base frame and another free end, an armature having a base end and a tip end to which a printing wire is rigidly connected, and a magnifying mechanism. When the piezoelectric element is electrically energized, a displacement of the piezoelectric element is magnified and then transmitted to the printing wire. Between the base frame and the base end of the armature there is provided a vibration damping buffer member.

Abstract: A laminated piezoelectric element which includes a laminate of piezoelectric ceramic plates and inner electrodes. The piezoelectric ceramic plates are laminated alternately together with the inner electrodes. The laminate is cut so as to have a peripheral surface. A positive outer electrode is connected to one group of inner electrodes at a peripheral surface of the laminate, and a negative outer electrode is connected to another group of inner electrodes at the peripheral surface of the laminate. A coating of fine ceramic particles is applied to, or a ceramic layer is sputtered on, the peripheral surface of the piezoelectric ceramic plates so that the insulation between adjacent inner electrodes is improved.