Method for recognizing the leading edge of a character in E13B font

Claim 1

A method of determining the start of a character in character data printed on a document in magnetic ink in which the start of a character included in said character data always begins with a positive-going signal, and in which the characters in said character data are formed of various combinations of positive peak values, negative peak values, and substantially zero values, said method comprising the steps of: (a) moving said document in reading relationship with a magnetic reader to generate a waveform corresponding to the character data on said document; (b) sampling said waveform at periodic times to generate voltage samples; (c) finding a positive-going voltage sample from step (b) which exceeds a predetermined threshold level; (d) using said positive-going voltage sample from step (c) to initiate the start of an examining window whose duration is equal to a predetermined number of said voltage samples; (e) examining the voltage samples within said examining window from the start thereof to an end thereof to find the highest voltage sample therein; (f) examining said voltage samples in an examining order proceeding from the highest voltage sample from step (e) towards the start of said examining window to find a point at which one of said voltage samples becomes negative or the start of said examining window is reached to thereby include a group of positive voltage samples within this examining step; (g) obtaining a calculated average for the voltage samples included in the group of voltage samples from step (f); (h) finding the first voltage sample in said group of voltage samples which is greater in voltage than the calculated average from step (g); and (i) using said first voltage sample from step (h) as the calculated character starting position (CCSP) for character recognition.

Claim 2

A method of determining the start of a character in character data printed on a document in magnetic ink in which the start of a character included in said character data always begins with a positive-going signal, and in which the characters in said character data are formed of various combinations of positive peak values, negative peak values, and substantially zero values, said method comprising the steps of: (a) moving said document in reading relationship with a magnetic reader to generate a waveform corresponding to the character data on said document; (b) sampling said waveform at periodic times to generate voltage samples; (c) finding a positive-going voltage sample from step (b) which exceeds a predetermined threshold level; (d) using said positive-going voltage sample from step (c) to initiate the start of an examining window whose duration is equal to a predetermined number of said voltage samples; (e) examining the voltage samples within said examining window from the start thereof to an end thereof to find the highest voltage sample therein; (f) examining said voltage samples in an examining order proceeding from the highest voltage sample from step (e) towards the start of said examining window to find a point at which one of said voltage samples becomes negative or the start of said examining window is reached to thereby include a group of positive voltage samples within this examining step; (g) obtaining a calculated average for the voltage samples included in the group of voltage samples from step (f); (h) finding the first voltage sample in said group of voltage samples which is greater in voltage than the calculated average from step (g); and (i) using said first voltage sample from step (h) as the calculated character starting position (CCSP) for character recognition.