The control circuit operates as a self-excited generator. The resonant frequency of the piezoresonator determines the vibration frequency of the circuit, independent of working conditions, temperature and aging effects.
Figure 4 shows the block diagram of the circuit. It consists of the piezoresonator 2 of the motor with the main electrodes 1;3. These ones are connected with the exit of the power amplifier. The auxiliary electrode 4 of the piezoresonator provides the actual value for the frequency control.

Figure 5 shows typical measured parameters in dependence on the torque M. All motors have gone in for a 12 hours' long-duration test, which causes the adaptation of the friction partners.
The diagrams of figure 5 have been measured with 12 V operating voltage. The input current of the control electronic is 130 mA, the maximal mecanical performance 170 mW at a torque of 0,04 Nm and the maximal rotational speed is 80 rpm at a torque of 0,01 Nm.

Directions for Application

Depending on the principle lamina-motors have only one direction of rotation. They are well suited at all situations, where the use of customary DC-motors with a gear is problematic, for instance by causing a slow, unidirectional rotational motion (size, structural form, weight).

The motors do not showemit a stray magnetic field, and optionally they can be manufactured of non-magnetic materials, allowing an operation within high magnetic fields. The electric radiation of the motors can be screened off easily.

The motors are not inflammable, they do not produce sparks, and they are suited for surroundings with a high explosion hazard.

The rotational speed of the motors can be reduced, similar to a DC-motor, by decreasing the working stress. The motor operates similar to a stepping motor by pulse-width modulation technique of the control voltage. The motors have an excellent start-stop performance with reaction times in a range of milliseconds and possible cycle times of some 100 Hz.