Radiation sensitive strip width measuring unit and split edge detector

Claim 1

Apparatus for monitoring the width of a material strip comprising: a light source; two transmitting light guide members formed from noncoherent bundles of light conducting fibers which optically connect to said light source and which conduct light from said light source to an end of each transmitting light guide member; a light transmitting head connected to the end of each transmitting light guide member; a path over which said material strip is to be passed, said path having two edges; means for moving said light transmitting heads and for positioning said heads at opposite edges of the path over which said material strip is to be passed; light sensitive means for measuring and for indicating the quantity of light received; two receiving light guide members formed from noncoherent bundles of light conducting fibers which optically connect to said light sensitive means and which conduct light from an end of each receiving light guide member to said light sensitive means; a receiving head connected to the end of each receiving light guide member and positioned opposite a transmitting head; means for passing said material strip along said path so as to intercept a portion of said light; and means for providing relative motion between said material strip and said light guide members; whereby deviation in the width of said material strip is indicated by said light sensitive means according to the level of light interception, and whereby sidewise motions of said strip do not substantially alter the indication of said light sensitive means.