Photosensitive digital shaft encoder

Claim 1

OPTICAL ENCODING APPARATUS COMPRISING A RADIATION SOURCE, MEANS RESPONSIVE TO RADIATION FROM SAID SOURCE, A CODED DISK ROTABLY MOUNTED FOR SELECTIVELY DIRECTING SAID ROTATION SO AS TO ACUATE DISCRETE PORTIONS OF SAID RADIATION-RESPONSIVE MEANS IN ACCORDANCE WITH THE ANGULAR POSITION OF SAID DISK, SAID DISK HAVING A PLURALITY OF CONCENTRIC ANNULAR TRACKS THEREON, EACH TRACK BEING DIVIDED INTO A RESPECTIVE PLURALITY OF ALTERNATING RADIATION-DIRECTIVE AND RADIATION-ABSORBENT SEGMENTS ACCORDING TO A PREDETERMINED DIGITAL CODE, THE TRACK OF LEAST RADIUS HAVING ITS PLURALITY OF SAID SEGMENTS CORRESPONDING TO THE LEAST SIGNIFICANT DIGITS OF SAID CODE, EACH TRACK OF SUCCESSIVELY LARGER RADIUS HAVING ITS RESPECTIVE PLURALITY OF SAID SEGMENTS THEREOF CORRESPONDING TO RESPECTIVE SUCCESSIVE GROUPS OF MORE SIGNIFICANT DIGITS OF SAID CODE, THE TRACK OF GREATEST RADIUS HAVING ITS PLURALITY OF SEGMENTS CORRESPONDING TO THE MOST SIGNIFICANT DIGITS OF SAID CODE, AND MEANS POSITIONED BETWEEN SAID DISK AND SAID RADIATIONRESPONSIVE MEANS, FOR LIMITING RADIATION TRANSMITTED FROM SELECTED RADIATION-DIRECTING SEGMENTS TO RESPECTIVE ONES OF SAID DISCRETE PORTIONS AND COACTING WITH EACH OF SAID SELECTIVE SEGMENTS FOR PROVIDING TO EACH OF SAID RESPECTIVE PORTIONS A RADIATION LEVEL OF A MAGNITUDE FOR SEGMENTS OF ANY ONE TRACK SUBSTANTIALLY THE SAME AS FOR SEGMENTS OF ANY TRACK AND FOR PROVIDING A TRANSITION SLOPE FOR SEGMENTS OF ANY ONE TRACK SUBSTANTIALLY THE SAME AS FOR SEGMENTS OF ANY OTHER TRACK.