Tray drive and slide change control apparatus for slide projector

摘要

Control apparatus is provided for a slide projector to accurately control rotation of a slide tray to predetermined slide positions of the slide tray and to provide integrated control of the slide change function at each slide position. The control apparatus operates in a forced mode between slide positions and operates in a servo mode to accurately position the slide tray at each of the predetermined slide positions. The detection of the slide positions utilizes a circumferential, apertured ring carried on a movable turntable that also carries the slide tray; the ring including a single incremental position aperture corresponding to each of the slide positions. Dual photodetectors are positioned at a sensing station to sense the respective slide position apertures, to provide differential position feedback detection signals in a servo loop, to interrupt the forced mode of operation and for controlling the stopping and positioning of the slide tray to a selected slide position in the servo mode. The control apparatus is operable by a forward/reverse selector switch in a first manual arrangement. Further, the control apparatus is also operable to advance to successive slide positions in response to a control signal derived as a tape advance signal from a cassette tape at variable, preprogrammed intervals. A random access slide projector is provided in another arrangement with the control apparatus being actuated either by decoded slide addresses from a program tape, or by the direct input from a local or remote keyboard.