Load detector for automatic storage apparatus

Claim 1

Apparatus for detecting the presence of a load in a bin of a storage rack of the type which has a plurality of bins arranged in rows and columns horizontally and vertically, and which is serviced by a horizontally movable load carrier that carries a single elevator movable into registry with any selected bin in said rack, said elevator having thereon a transfer member and means operable to insert a load through an open end of said selected bin onto load supporting means therein, said apparatus comprising cooperating members on the rack and the elevator, respectively, and comprising retro-reflective elements fixed on said rack at the backs of the several bins remote from the open ends of the bins, with their reflective surfaces facing said open ends, a reflex photocell mounted on said elevator below the upper surface of said transfer member, a light source associated with said photocell, means for energizing said light source only when said elevator registers with a selected bin said light source being operative, when energized, to direct a beam of light diagonally upwardly into said selected bin at an angle to the horizontal, and onto the retro-reflective element disposed in said selected bin, whereby only when said selected bin is empty, is the element operative to reflect light back toward said source along the axis of the beam of light emitted by said source, light-responsive switch means contained in said reflex photocell to control said transfer member, said light-responsive switch means being disposed to receive reflected light from said surface, when said selected bin is empty, and to be blocked off from said reflected light, when there is a load in said bin, and control means responsive to said switch means to operate said transfer member, when said reflected light falls on said switch means, and to prevent operation of said transfer member, when a load in said selected bin prevents light from being reflected back onto said switch means.