A control system comprises a liquid crystal display panel; a light source; light detector means; and means for directing light through at least a portion of the liquid crystal display panel to the light detector means. Control means are provided for holding the liquid crystal display in generally opaque condition while preferably sequentially momentarily clarifying segments of the portion, whereby momentary, sequential, transversely spaced light beams are generated between the light source and the light detector means. Timer and logic means are provided for correlating signals received from the light detector means with generated, individual, spaced light beams that create said signals. Accordingly, occlusion of at least one of the individual light beams with an opaque member causes a specific characteristic response by the timer and logic means.; In other words, when one of the individual light beams is occluded, the timer and logic means emits a characteristic signal which might activate a relay, send an instruction to a microprocessor, or cause some other action.