A HIGH-SPEED IMPACT ACTUATOR USING MULTILAYER PIEZOELECTRIC CERAMICS

An impact actuator using multilayer piezoelectric ceramics is proposed and evaluated. The actuator includes a mutilayer piezoelectric element, an impact hammer and a solid waveguide interposed between the piezoelectric element and the hammer. The principle of design is the use of a stress wave which is generated by the prestressed piezoelectric element when an electric pulse is applied. The waveguide transmits the stress wave to the impact hammer, and launches the hammer at a high initial velocity. A multilayer piezoelectric element 2 by 3 mm in cross section and 18 mm in length can launch a 0.15 g hammer to achieve a velocity of 263 cm/s, which is equivalent to a kinetic energy of 0.52 mJ. After the hammer flies forward to strike an object, it returns to the waveguide and hits the piezoelectric element. The piezoelectric element then acts as a sensor to detect the impact of the hammer in contact with the waveguide. In response to that detection, a consecutive pulse can be triggered to enable the actuator to operate. This principle is applied to the design of an actuator for high speed dot matrix printing. The results presented here demonstrate the capability of high speed operation and high energy transfer efficiency with large hammer travel.