Patent 7942232 was granted and assigned to Kayaba Industry on May, 2011 by the United States Patent and Trademark Office.
A controller samples a motor current value detected by a motor current detector at a sampling start timing for turning on a switching device to start holding in a motor current hold section, and fetches the motor current value held in the motor current hold section at a hold timing for turning off the switching device. The sampling start timing and the hold timing are variable.