| 摘要 |
A character reader recognition data extracting device for use in an optical character reader system for reading characters printed in magnetized ink. Characters printed in magnetized ink on a substrate are magnetized with a magnetic polarity opposite that of stray magnetic particles which may adhere to a conveying roll for the substrate. Signals produced at the output of the magnetic head due to the presence of the stray particles are discriminated from those produced in response to the characters due to the differences in magnetic polarity. A processing circuit is disclosed which operates upon the output signal from the magnetic head to provide digital signals representative of the sensed characters. This circuit includes a sample-and-hold circuit, an offset circuit and comparators which compare the output of the sample-and-hold circuit shifted by the offset circuit with the unshifted signal at a prior sampling period.
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