ОБНАРУЖЕНИЕ МЕТКИ СОВМЕЩЕНИЯ ПРИ ИСПОЛЬЗОВАНИИ СОГЛАСОВАННОЙ ФИЛЬТРАЦИИ

摘要

A system and method for detecting a registration mark associated with an object which provides improved resolution between matching and non-matching inputs. The registration mark represents a binary code sequence. Upon detecting a sequence of bits with a sensor, the detected sequence is provided to a code matching filter, which compares the detected sequence with the binary code sequence and produces a detection signal. The code matching filter increases a value of the detection signal for each matching pair of compared bits, and decreases the value of the detection signal for each non-matching pair of compared bits. In this manner, a penalty is assessed for mismatches. This results in a filter output having a high amplitude in response to a matching input, and a low amplitude for non-matching inputs. The system may sample the detected sequence of bits in such a manner as to avoid potential edge timing problems.