| 摘要 |
PROBLEM TO BE SOLVED: To obtain a circuit for aligning the print position of a plurality of thermal heads in which the accuracy of print position is enhanced. SOLUTION: The circuit for aligning the print position comprises a plurality of thermal heads, synchronization pattern sensors 11, 12 and 13 associated therewith, and a section 24 for calculating the phase difference of mark positions detected by these sensors. The circuit for aligning the print position further comprises a counter which up counts every time when the synchronization pattern sensors 11, 12 and 13 perform an operation for detecting the interval of marks put on a sheet, and means for holding the initial value of interval between the marks. Elongation/shrinkage of the sheet is detected based on comparison of the initial value thus held and the count in the counter. Timing for delivering image data to each head is regulated based on detection of elongation/shrinkage of the sheet and print operation is stopped if step-out exceeds a specified value thus enhancing the accuracy of print position.
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