Photosensitive apparatus for detecting a flaw in material with steady illumination means

Claim 1

ILLUMINATION AND OPTICAL SENSING COMPARISON APPARATUS FOR USE WITH A RELATIVELY MOVING SAMPLE MATERIAL, COMPRISING: A FIRST SOURCE OF HIGH FREQUENCY A.C. POWER, A SECOND SOURCE OF LOWER FREQUENCY A.C. POWER, MEANS FOR PHASE SPLITTING POWER DERIVED FROM SAID SECOND SOURCE AND FOR USING PHASE SPLIT SECOND SOURCE POWER TO MODULATE POWER DERIVED FROM SAID FIRST SOURCE IN TWO SUBSTANTIALLY DIFFERING PHASE RELATIONSHIPS, A LIGHT SENSING MEANS, A FIRST LAMP CONNECTED TO BE ENERGIZED FROM SAID SOURCES IN ONE OF SAID TWO PHASE RELATIONSHIPS, A SECOND LAMP CONNECTED TO BE ENERGIZED FROM SAID SOURCES IN THE OTHER OF SAID TWO PHASE RELATIONSHIPS, A LIGHT SENSING MEANS, AND MEANS FOR MOUNTING SAID LIGHT SENSING MEANS AND SAID LAMPS STATIONARY WITH RESPECT TO THE MOVING SAMPLE MATERIAL AND SO THAT THE FIRST LAMP PROVIDES ILLUMINATION WHICH BY COUPLING WITH ONE INSTANTANEOUSLY DISTINCT PORTION OF THE SAMPLE MATERIAL ILLUMINES THE SENSING MEANS WHILE THE SECOND LAMP PROVIDES ILLUMINATION WHICH BY COUPLING WITH ANOTHER INSTANTANEOUSLY DISTINCT PORTION OF THE SAMPLE MATERIAL ILLUMINES THE SENSING MEANS, WHEREBY TO PROVIDE SUBSTANTIALLY STEADY ILLUMINATION OF SENSING MEANS EXCEPT WHEN THE RELATION IS DISTURBED BY A FLAW AT EITHER OF SAID DISTINCT SAMPLE PORTIONS.