Abstract: Mechanism primarily suited to automatic sliding door applications wherein at least a pair of object presence sensing detectors, preferably of the ultra-sonic transducer type are arranged to be placed in linear spaced relation to one another effective to cast sonic beams produced thereby spanning the doorway to which applied. So as to assure satisfactorily a beam path to be intercepted by an object stationary or moving in the beams, they are purposely overlapped. The door upon being operatively moved by motion sensing detectors or manual means acts at different opening positions to switch the object sensing detectors on and upon reverse closing positions switches the object sensing detectors off.

Abstract: A system for controlling the opening and closing operation of a sliding door wherein at least two presence sensing detectors are disposed effective to cast beams in overlapping relation to one another and extending across the pathway of the door to be controlled, and manual means or motion detecting detectors effective to provide for the initiation of movement of the door to open position. Furthermore programmed computer means are included in the system for the controlled sequencing and pulsing of the presence sensing beams in the opening and closing operation of the door.

Abstract: The flagstaff described herein comprises a hollow flag holding unit or sleeve preferably cylindrical in shape, capped at one end and having a longitudinal slot running at least a substantial portion of the length of the flag holding unit adapted to have a stiff, stitched or raised edge of a flag inserted into the holding unit with the flag extending through the slot with the major portion of the flag extending outside the holding unit. With flag in position the capped holding unit is positioned on a vertical staff with the cap resting on the top end of the staff. The flag edge will be retained in a straight line and the holding unit will rotate as the wind direction changes so that the flag will not wrap around the supporting means.