| 摘要 |
PURPOSE:To read quickly and accurately a bar code by scanning an surface containing a bar code and to be checked and then decoding the bar code according to both the regular and irregular reflected beams given from the area of the bar code. CONSTITUTION:Both the regular and irregular reflected beams of the laser light 6 are given fromma wafer 1 irradiated by the light 5 and condensed by an integration ball 19. The irregular reflected light quantity of the bar parts 33 is little smaller than that of the space parts 34. Therefore the voltage value corresponding to the parts 33 is much larger than that of the parts 34 for the electric signal SF delivered from an adder 29 and showing the sum of both electric signals SD and SE delivered from the 1st and 2nd amplifiers 27 and 28 respectively. Therefore the threshold voltage level VT is set previously to a binary coding circuit 30 for discrimination of the parts 33 from the parts 34. The signal SF supplied to the circuit 30 is binary coded by the level VT. Then the binary coded signal SG is delivered to a decoder 31.
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