| 摘要 |
A commercially available dot matrix printer is converted to a document printer by removing the tractor feed sprockets and shaft substituting a pinch roller, rubber roller combination, the roller having a shaft connected to the same stepper motor as the tractor shaft; supplying three positions sensors, a load sensor for detecting a document causing it to be stepped by the rubber-pinch roller combination to the printer head-anvil combination where two more laterally spaced sensors are located so as to measure skew of the document and to further processing of the document if both sensors do not detect the presence of a document essentially concurrently and to turn control of the printer over to the printer's control circuits for further processing when both sensors are activated essentially concurrently.
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