Light projecting and absorbing apparatus in a system for selecting automatically desired music in phonographic player

Claim 1

A detecting unit for an automatic tune selection system of a phonographic record player comprising a light projector adapted to project light rays from a light source onto a portion of a face of a record disc and a CdS photoelectric element adapted to be impinged upon by the reflections of said light rays, a cylindrical casing housing said light projector and said photoelectric element, a light barrel shield fixed to the lower end portion of said casing and extending downwardly therefrom and having a constricted aperture formed on the lower end thereof, said photoelectric element being secured in said casing downwardly from said light source and upwardly from said constricted aperture, a light shield disc disposed on top of and in abutting relationship with said photoelectric element, said photoelectric element and light shield disc having a passage bore formed through the centers thereof providing a passage for said light rays of said light source which are projected therethrough, said constricted aperture forming a passage for both outgoing light rays of said light source and incoming reflections of said light rays reflected from a portion of the face of said record disc, the constricted aperture having a diameter which is substantially smaller than the diameter of said photoelectric element and also smaller than the inner diameter of said casing as well as the diameter of said light shield barrel, thereby forming a limited passage for the exclusive reception of sharp angled reflections of said light rays of said light source.