Motor driven extensible rod antenna for vehicles with position control circuit

Claim 1

An electric antenna apparatus for vehicles, comprising: an antenna rod; a rotary member for driving a cable coupled to said antenna rod, in the longitudinal direction of the antenna rod, and extending and retracting said antenna rod; a motor, provided with an output shaft coupled thereto by a reducing mechanism constituted by a worm wheel, for rotating said rotary member; pulse signal generating means placed in a non-contact state with said rotary member and including a rotation detecting plate rotatable coaxially with the worm wheel, said pulse signal generating means generating a pulse signal in response to the rotation of the rotation detecting plate, which takes place when said rotary member rotates in response to the extending or retracting of said antenna rod; drive means provided with a control circuit to which the pulse signal generated by said pulse generating means is supplied and which drives and controls said motor so as to extend or retract said antenna rod; antenna rod position signal setting means which is provided within the control circuit of said drive means and which counts the pulse signal generated from said pulse signal generating means and stores the count value corresponding to the position of said antenna rod; stop position set instructing means for setting each stop position such as the fully-extending position, enclosed position, and middle position, etc., of said antenna rod; pulse count value setting means for setting a pulse count value corresponding to each of said stop positions in response to a command from said stop position set instructing means; operation command generating means which compares the pulse count value set in response to the command from said stop position set instructing means with the count value stored by said antenna rod position signal setting means, thereby generating an operation command for extending or retracting said antenna rod to said motor; stop control means for generating a stop command to said motor when the pulse count value corresponding to said stop position coincides with said count value stored in said antenna rod position signal setting means; and a circuit board into which the control circuit of said drive means is installed and which is located adjacent to said motor, said circuit board being provided with signal detecting means which constitutes said pulse signal generating means.