Patent ID: 7183737

Claim:
A device for controlling a motor by means of a switching element, wherein: the device outputs a pulse-like control signal to the switching element, the control signal being switched between high level and low level for selectively turning on or off the switching element such that the motor is supplied with a current in correspondence with a turned on state of the switching element; the device samples and holds the current supplied to the motor for a predetermined sampling and holding time for obtaining a value of the motor current, the device controlling the motor in accordance with the obtained value; the device determines, as the sampling and holding time, a time period between a first point in time when the level of the control signal is switched for turning off the switching element and a second point in time that precedes the first point in time by a predetermined period; the device generates the control signal by comparing a delta wave variation with a predetermined first comparative value, the delta wave variation being varied in a delta wave manner or in an alternating, gradually increasing and quickly dropping manner; and the device generates a pulse-like sampling and holding signal by comparing the delta wave variation with a predetermined second comparative value, the sampling and holding signal being switched between high level and low level, the device determining, as the sampling and holding time, the time period during which the sampling and holding signal is maintained at high level or low level.