are grounded the first electrodes 30 and the first electrodes 34 of the actuator fingers 22 and the support fingers 24 are all interconnected by a common line 42 ohmic resistances and other impedances capacitances and inductivities between the neighboring first electrodes 30 34 are represented by impedance elements 44 if these impedances are neglected then all first electrodes 30 34 of the actuator fingers and support fingers are kept at a common potential which depends upon the balance between the voltage drops at the parallel circuit formed by the various actuator fingers 22 on the one hand and the parallel circuit formed by the various support fingers 24 on the other hand thus the potential of the common line 42 relative to ground increases in proportion with the number of actuator fingers 22 to which energizing pulses 40 are applied and the potential of the line 42 and hence the potential of the first electrodes 30 34 will always be between the potential of the second electrodes 32 of the active actuator fingers and ground the electric field generated between the first and second electrodes 34 36 of the support fingers 24 will always be opposite to the electric field generated between the first and second electrodes 30 32 of the actuator fingers 22 accordingly if the piezoelectric material of all transducers i e of the actuator fingers 22 and of the support fingers 24 has the same polarisation an expansion of the actuator fingers 22 will always be accompanied by a contraction of the support fingers 24 and vice versa in addition since the first electrodes 30 and 34 of the actuator fingers 22 and the support fingers 24 are disposed on the same level these electrodes may easily be interconnected by a conductor forming the common line.