Patent ID: 7861796
Filing Date: 2011-01-04
Classification: B25B,B25F,H01H,H02P,Y10S

Abstract:
1. A method of operating a hand power tool comprising: generating a variable speed control signal with a solid state switch in correspondence with a reflected optical signal that corresponds to a selected speed for a motor; generating a pulse width modulated (PWM) signal corresponding to the variable speed control signal; generating H-bridge driving signals for an H-bridge circuit in correspondence with the PWM signal; selectively coupling a motor to a power source using the H-bridge circuit in accordance with the H-bridge driving signals; traversing a moveable member having a reflective surface through a distance between a stop position and a full speed position; biasing the moveable member toward the stop position; and directing an optical signal toward the reflective surface of the moveable member to generate the reflected optical signal.