Abstract

An electro-optical control comprising a housing, a source of light, a photocell, and an endless belt having a substantially planar run manually movable with a finger. The belt has portions of differing light penetrability. Members on the housing guide the belt in an endless path when the one run of the belt is manually moved. The photocell and the light source are positioned interior of and exterior of the belt. Thus, when the belt is moved, the amount of light from the light source which strikes the photocell is varied, controlling the photocell. The control can include a stop member secured to the belt, engageable with the housing to limit the movement of the belt. In an alternative embodiment, the control includes a light source, a pair of photocells positioned substantially side by side and first and second disc-shaped polarizing filters positioned between the light source and the photocells. One filter is manually rotatable. One filter is also divided into two substantially semicircular filter portions whose directions of polarization are perpendicular to each other so that as the rotatable filter is rotated, the amount of light from the source striking one of the photocells is increased and the amount of light striking the other of the photocells is simultaneously decreased. The rotatable filter is controlled through an endless belt. An endless belt can also control for example a linear motion variable resistor or other devices.

Other References

• L R. Moskowitz, "Selecting Magnets for Reed Switch Actuation" Automation-Oct. 1968; pp. 66-71