| 摘要 |
PROBLEM TO BE SOLVED: To provide a control method which does not place a large load on a galvanomirror during vertical-scanning-directional position control over a laser beam. SOLUTION: This method has a step S14 wherein the drift direction of the galvanomirror is estimated from a last indication value when a vertical scanning beam position does not enter a target range with the last indication value, an indication value is given to the galvanomirror to move the vertical scanning beam position from the position corresponding to the last indication value in the estimated vertical scanning beam direction by a specific quantity at each time, and it is judged whether or not the indication value given to the galvanomirror reaches a specific value and a step S7 wherein an indication value is given to the galvanomirror so that the vertical scanning beam position moves from the position corresponding to the last indication value in the opposite direction from the predicted direction by a specific quantity at each time when the indication value reaches the specific value.
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