Patent ID: 6678999
Filing Date: 2004-01-20
Classification: E05F,E05Y,G01S

Abstract:
An object sensor for use with an automatic swing door, comprising:a light emitter mounted on a door surface of said automatic swing door for emitting and projecting a light beam toward a floor surface where said swing door is installed; a position sensitive device mounted on said door surface for receiving said light beam as reflected from an object, a position on said light sensitive device at which said light beam reflected from said object is incident changing as a distance of said object from said position sensititve device changes, said position sensitive device outputting a digital distance-representative signal having a value representative of the distance of said object from said position sensitive device, said value of said digital distance-representative signal varying in accordance with said incident position on said position sensitive device of said reflected light beam; and a control unit making a judgment as to whether or not said object is approaching said door surface based on the value of said digital distance-representative signal of said position sensitive device; wherein: said control unit causes memory means to store therein, as a reference value, the value of said digital distance-representative signal which said position sensitive device outputs when said light beam is projected toward said floor surface in the absence of any object in the vicinity of said door, said memory means having stored therein a value representative of a predetermined height from a structure including said floor surface; and said control means, in an object detecting mode of operation, computes from said reference value and said predetermined height representative value, a value representing a distance from said position sensitive device to a boundary of a dead zone at said predetermined height from said structure including said floor surface, and judges that an object is approaching said door when the value of said digital distance-representative signal developed by said position sensitive device is smaller than said value representing the distance from said position sensitive device to said boundary of said dead zone.