When such piezoelectric components, which are produced in particular from piezoceramics, are used, use is made of the effect whereby these components generate a voltage when a mechanical pressure or tension is applied, or conversely an extension of the actuator can be achieved by applying an electric voltage to the piezoactuator. In order to increase the usable extension length, monolithic multilayer actuators are used which consist of a sintered stack of thin films of piezoceramic with embedded internal electrodes. The internal electrodes are alternately brought out of the stack and electrically connected in parallel via external electrodes. A strip- or band-shaped end-to-end external metallization is preferably attached to both contact sides of the stack. The external metallization is connected to all the internal electrodes of equal polarity. A further contacting element, which can be fashioned in a plurality of forms, is frequently also provided between the external metallization and the electrical terminals. If a voltage is now applied to the external metallization, then the piezofilm extends in the direction of the applied field. As a result of the mechanical series connection of the individual piezofilms, the so-called nominal extension of the entire stack is reached even at relatively low voltages.
From EP 0 844 678 A1 a contacting method is known, with the aid of which a piezoceramic can be contacted such that destruction of the piezoactuator does not occur, even at high dynamic loadings. To this end, a three-dimensionally structured electrically conductive electrode is arranged between the ground metallization of the piezoceramic and the connecting elements. This electrode is connected via partial contact points to the ground metallization of the piezoceramic. It is fashioned extensibly between the contact points. This arrangement provides that the operating current of the actuator is subdivided into secondary currents, these flowing from the contact points via the ground metallization to the metal island electrodes. It can by this means be provided that even a dynamic loading of the piezoactuator does not lead to its destruction. However, the contacting is technically complex and expensive to execute.
USPTO Backgrounds
USPTO Backgrounds