Stepping motor control device for automobile air-conditioning system

A stepping motor control device for an automobile air-conditioning system comprising:

• a stepping motor for driving an air-mix door of said automobile air-conditioning system;
• memory means, which is supplied with power from a car mounted battery irrespective of an on/off condition of a key switch of the automobile, for storing data;
• key-off home-position setting means, responsive to an off condition of said key switch of the automobile, for performing a home-position setting of said stepping motor, said key-off home-position setting means driving said stepping motor so that said air-mix door is driven to a full-close position to be in a or a full-open position to be in a and storing data indicative of the full-close or full-open position in said memory means;
• timer means, responsive to the off condition of said key switch of the automobile, for supplying power to said key-off home-position setting means for a prescribed time within which said key-off home-position setting means can finish the home-position setting;
• and
• key-on control means, responsive to an on Condition of said key switch of the automobile, for determining whether the data representing the full-close position and full-open position is stored in said memory means, for starting a normal air-conditioning control without performing the home-position setting of said stepping motor when the data is stored in said memory means, and for starting the normal air-conditioning control after performing the home-position setting of said stepping motor when the data is not stored in said memory means.

An air-conditioning system for an automobile comprising:

• an actuator for opening and closing an air-conditioning door of the air-conditioning system;
• a switch for turning the automobile on and off;
• a memory for storing data;
• and
• control means, coupled to said switch and said memory, for (a) instructing said actuator to drive said air-conditioning door to a full-close position or a full-open position and storing position data indicative of a current position of said air-conditioning door in said memory, in response to manipulation of said switch to an off position and (b) instructing said actuator to drive said air-conditioning door to a full-close position and thereafter entering a normal air-conditioning control mode upon determination that the position data is not stored in said memory and directly entering the normal air-conditioning control mode upon determination that the position data is stored in said memory, in response to manipulation of said switch to an on position.