Photoelectric device for indicating spots on a surface

• US 3,091,699 A
• Filed: 08/31/1960
• Issued: 05/28/1963
• Est. Priority Date: 10/15/1959
• Status: Expired due to Term

• Current Assignee: Martin Hammar
• Original Assignee: Martin Hammar
• Inventors: Hammar, Martin
• Application Number:
  US04/053,139
• Time in Patent Office: 1,000 Days
• US Class Current: 250/559.44
• CPC Class Codes: G06K 7/10851 Circuits for pulse shaping, amplifying, eliminating noise signals, checking the function of the sensing device basic electronic circuitry H03

Claims

1. A DEVICE FOR INDICATING SPOTS AND THE LIKE ON A SURFACE TO BE SCANNED COMPRISING A LIGHT SOURCE FOR LIGHTING THE SURFACE, A LIGHT SENSITIVE MEMBER FOR GENERATING AN ELECTRICAL SIGNAL WITH A STRENGTH DEPENDING UPON THE INTENSITY OF THE LIGHT REFLECTED FROM THE SURFACE, A BACKGROUND SURFACE BEHIND SAID SURFACE TO BE SCANNED, MEANS FOR EFFECTING A POINT-SHAPED RECIPROCATING SCANNING LIGHT ACROSS THE SURFACE IN OPPOSITE DIRECTION FROM THE SCANNED SURFACE TO THE BACKGROUND SURFACE, EACH OF SAID SCANNINGS BEING ARRANGED TO START ON SAID SCANNING SURFACE AND TERMINATING OUTSIDE OF THE SIDE EDGES OF SAID SURFACE, SAID SCANNING OUTSIDE OF THE SIDE EDGES BEING ARRANGED TO TAKE PLACE AGAINST A BACKGROUND WHICH, WHEN INDICATING DARK SPOTS, HAS GREATER REFLECTION POWER THAN SAID SCANNING SURFACE, AND WHEN INDICATING LIGHT SPOTS, HAS LESS REFLECTION POWER THAN SAID SURFACE, AN INDICATING MEMBER, A DIFFERENTIATING MEMBER, SAID ELECTRIC SIGNAL BEING FED TO SAID INDICATING MEMBER THROUGH SAID DIFFERENTIATING MEMBER AND SAID INDICATING MEMBER IS ARRANGED TO BE ACTUATED BY PULSES OF A POLARITY WHICH IS OPPOSITE TO THE POLARITY OF THE PULSES GENERATED BY SAID DIFFERENTIATING MEMBER WHEN SAID SCANNING PASSES ONE OF SAID SIDE EDGES.