Method and apparatus for driving actuators using a shape memory alloy

1. An apparatus comprising:

an actuator having a shape memory alloy;

a pulse signal generating device outputs a pulse signal, wherein said pulse signal generating device stops the output of said pulse signal before said shape memory alloy transitions to a fully contracted state; and

a switch applies a pseudo single pulse voltage signal to said actuator, wherein said pseudo single pulse voltage signal is generated by performing switching control of a predetermined voltage according to a plurality of consecutive micro-pulse signals.

2. The apparatus of claim 1 , wherein said actuator is an impact-driven actuator that generates an aimed vibration in one thermal cycle.

3. The apparatus of claim 1 , wherein an off-period of said pulse signal is shorter than a period of time taken by said shape memory alloy to complete a phase transition from a fully contracted state to a fully extended state.

4. The apparatus of claim 1 , wherein an off-period of said pulse signal is shorter than a period of time until said shape memory alloy having contracted during an on-period starts to extend.

5. The apparatus of claim 1 , wherein an off-period of said pulse signal is shorter than a period of time until a temperature having risen during said on-period starts to decrease.

6. The apparatus of claim 1 , wherein said pulse signal generating device generates said plurality of successive pulse signals by pulse-width modulation control of a single pulse signal.

7. The apparatus of claim 1 , wherein said apparatus includes a keyboard.

8. An electronic device comprising:

a vibrator;

an actuator having a shape memory alloy that vibrates said vibrator;

an event generating device outputs an action event according to a finger operation on said vibrator;

a pulse signal generating device outputs a plurality of micro-pulse signals according to said action event, wherein said pulse signal generating device stops the output of said plurality of micro-pulse signals before said shape memory alloy transitions to a fully contracted state; and

a switch applies a pseudo single pulse voltage signal to said actuator, wherein said pseudo single pulse voltage signal is generated by performing switching control of a predetermined voltage according to said plurality of micro-pulse signals.

9. The electronic device of claim 8 , wherein said pulse signal generating device outputs said pulse signal by applying a normal single pulse voltage according to said action event.

10. The electronic device of claim 8 , wherein said pulse signal generating device outputs said a pulse signal by applying said plurality of micro-pulse signals according to said action event.

11. A method comprising:

driving an actuator with a single pulse voltage signal;

setting a parameter for adjusting a vibration intensity;

driving said actuator with a pseudo single pulse voltage signal generated by performing switching control on said single pulse voltage signal according to said parameter;

receiving an action event;

applying a plurality of micro-pulse voltage signals to said actuator according to said action event in a period shorter than a period of time taken by a shape memory alloy to complete a transition from a fully contracted state to a fully extended state; and

stopping said micro-pulse voltage signals after said transition of said shape memory alloy to said fully contracted state.