Back gauge position feed back signal generation

Servo control system feedback signal generator means comprising, in combination:

• rotatable input shaft means, first transparent marking disc means secured to said input shaft means for rotation in a plane normal to the rotational axis of said shaft means, said first transparent marking disc means having circumferentially spaced-apart opaque markings with uniformly spaced-apart edges which each correlate to an incremental change in the rotational position of said shaft means;
• a second transparent marking disc means supported for rotation about an axis, said second transparent marking disc means having circumferentially spaced-apart opaque binary-code patterns which each correlate to a different multiple turn control position of said input shaft means, gear train means coupling said second transparent marking disc means in driven and reduced rate of rotation relation relative to said first transparent marking disc means, lamp means positioned in cooperating relation to said first and second transparent marking disc means and to said opaque markings and patterns, and a pair of photoelectric light detector device arrays positioned in cooperating relation to said first and second transparent marking disc means and said opaque markings and patterns and in illuminated relation relative to said lamp means, one of said arrays producing binary-code signals correlated to different multiple turn control positions of said input shaft means, and the other of said arrays producing pulsed signals correlated to incremental changes in the positions of said input shaft means in intervals intermediate adjacent of said input shaft means multiple turn control positions.