Abstract: In an electrostriction transducer comprising protection layers (21, 22) in which no electric fields are produced during operation, each of end electrostriction layers (41, 42) which are contiguous to the respective protection layers with pertinent ones of internal electrodes (16, 17) interposed, is given a thicker thickness (at) as compared with other or intermediate electrostriction layers (23) to make the transducer have a long life and a high reliability. The intermediate electrostriction layers may have a common thickness (t). Alternatively, the intermediate electrostriction layers may have monotonously decreasing thicknesses when placed nearer to a plane which bisects a pile (19) of the electrostriction layers parallel to both end surfaces of the pile. When a pair of holding members for the transducer are used on both longitudinal ends, each protection layer is preferably received in an indent formed in the holding member.

Abstract: A drive circuit for a piezoelectric stack which drives a desired mechanical object such as a printing head of a dot matrix printer or an ink jet printer. A winding is connected in series with one of electrodes of the piezoelectric stack so that an excitation voltage is applied to the stack via the winding. An excessive charge current at each time of drive and an excessive discharge current at each time of recovery are prevented.

Abstract: In an impact printer head intermittently movable along a printing line and comprising a plurality of printer units (25) each of which has a thickness and a printing wire (30) having a printing end operable between rest and actuated positions along a line of displacement (R), a support member (45) supports the printing wires so that a distance between two adjacent ones of the printing ends becomes smaller than each thickness at the actuated positions. To this end, the printer units are radially disposed by the supporting member to make the lines of displacement form an acute angle for two adjacent printer units and to position the printing ends in a predetermined configuration at the actuated positions. The predetermined configuration may be a single straight line perpendicular or oblique to the printing line. Alternatively, the configuration may be a pair of straight lines orthogonal or inclined to the printing line.

Abstract: A multilayer electrostrictive element has electrostrictive sections (31) defined by internal electrodes (32) in a stack, with a peripheral surface which has a predetermined outline perpendicularly of an axis of the stack, each internal electrode with an outline which is approximately congruent with the predetermined outline (constant cross-section). In order that external electrodes (33, 34) may readily be connected to the internal electrodes grouped by twos, each internal electrode may have a peripheral end which is partly recessed from the predetermined outline, as in FIG. 8. Alternatively, the internal electrodes of each group may be connected together by a conductor rod which passes through the electrostrictive sections, preferably along their edges, contacting alternate electrodes. For a great number of internal electrodes, an element may be manufactured by laminating conductive-paste-printed green sheets transversely of the stack axis and then sintering the lamination.

Abstract: In a differential lever actuator comprising transmission members (41, 42) for differentially transmitting oppositely sensed angular displacements from first and second weight points (P1, P3) of first and second lever members (31, 32) to first and second predetermined points (P2, P4) of a differential lever member (41), a distance between midpoints (S, T) between the first weight and predetermined points and between the second weight and predetermined points is kept constant irrespective of the angular displacements. Preferably, at least one transmission member should be perpendicular to a line passing through the related weight point and a fulcrum point (Q or R) of the associated one of the first and second lever members. When carried by the differential lever member for print of a dot, a rod should preferably have an axis passing through a point of intersection of the transmission members.

Abstract: A transducer (51) extended by an electroexpansive longitudinal effect, actuates a lever (77) through a bendable plate (56). Preferably, the plate actuates a first arm (53) having an end which provides the fulcrum. Another bendable plate (79) actuates a second arm (76) having an end which exterts the power to the lever. The plates are symmetrically disposed on both sides of the transducer axis. The lever is differentially actuated by the arms. When such lever actuators are combined into an impact printer head, a guide for printing elements carried by the respective levers are preferably used in preventing the levers from excessively excursing.