Patent ID: 8253370

Claim:
A microcomputer that controls an ultrasonic motor, the microcomputer comprising: a storage unit that stores a compare register value, and a digital/analog, D/A, conversion set value; a D/A converter that generates an amplitude control signal with an amplitude value corresponding to the D/A conversion set value; a timer that generates a pulse width modulation, PWM, signal with a frequency corresponding to the compare register value; a central processing unit, CPU, that reads the D/A conversion set value, and the compare register value from the storage unit; and that sets the D/A conversion set value and the compare register value to the D/A converter and the timer, respectively; and an output circuit that generates the control signal with the amplitude of the amplitude control signal, and the frequency of the PWM signal, in response to the amplitude control signal and the PWM signal, wherein the compare register value allows for determining a frequency of the control signal corresponding to a target rotation speed that is targeted by the ultrasonic motor, and wherein the D/A conversion set value allows for determining an amplitude of the control signal corresponding to the target rotation speed that is targeted by the ultrasonic motor.