| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of efficiently and rapidly printing characters of a wide width on a continuous sheet by a fixed type ink jet head of a small size and a high resolution. SOLUTION: In a printing unit 12, the ink jet head 14 obtained by spirally assembling many printing heads disposed concentrically around a fixedly disposed cylindrical printing drum 13 and directly near a peripheral surface of the drum. A spiral recess 13a having the same inclining angle as that of the head 14 is formed on a peripheral surface of the drum 13, a recording sheet 31 is wound in a tensioning state on the recess, and the sheet 13 is maintained in the tensioning sate in a range from a sheet feeder 30 to a recording sheet recovery unit 40 via the drum 13. Printing is conducted while vertically moving the head 14 in a predetermined state by a vertically moving mechanism 16 and while slidably running the sheet 13 on the drum 13 on the peripheral surface of the drum 13 by a running recovering operation of the sheet 31 by the unit 40.
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