To provide a liquid drop discharging body operating through a thermomechanical means, and a thermomechanical liquid drop discharging body generating a series of liquid drop groups having substantially identical volume and velocity.

The liquid drop discharging body, e.g. an ink jet unit, for discharging a series of liquid drops with a high frequency comprises a chamber, a thermomechanical actuator, means for overheating the thermomechanical actuator in response to an electric pulse, and a controller. The operating method includes determination of a nominal electric pulse, and a steady state electric pulse. The method is applied to a heating means where the nominal electric pulse or the steady state electric pulse is applied during each time period TC and an average power PAVE=E0/TC is applied to the liquid drop discharging body in order to sustain the thermal conditions of steady state.