Patent ID: 8517500

Claim:
A method comprising: applying a voltage to a piezoelectric actuator structure of a droplet ejector unit; detecting whether a voltage at a drain of a transistor is above a predetermined voltage, the transistor being connected to the piezoelectric actuator structure; and disabling the piezoelectric actuator structure by applying a voltage that is below a gate threshold voltage at a gate of the transistor, wherein disabling the piezoelectric actuator structure comprises outputting a signal by an SR flip-flop that causes the voltage below the gate threshold voltage to be applied to the gate of the transistor if the voltage at the drain of the transistor is above the predetermined voltage while the voltage at the gate of the transistor is higher than the gate threshold voltage, using an output of the SR flip-flop and an output of an OR gate as inputs to an AND gate, wherein the AND gate applies the voltage to the gate of the transistor, wherein the SR flip-flop outputs a low signal to the AND gate if the voltage at the drain of the transistor is higher than the predetermined voltage while the voltage at the gate of the transistor is higher than the gate threshold voltage.