| 摘要 |
A printing apparatus ( 10 ) exposes an image onto a photosensitive medium ( 14 ), having a printhead ( 20 ) with a linear array of exposure sources ( 40 ), each exposure source ( 12 ) operable at a variable intensity. A shuttle mechanism ( 16 ) moves the printhead ( 20 ) over the photosensitive medium ( 14 ) in a reciprocating motion between one end of a carriage assembly ( 72 ) and the other. An encoder ( 38 ) is coupled to the shuttle mechanism ( 16 ) for providing an index encoder pulse ( 60 ) at each of a plurality of increments of position of the shuttle mechanism ( 16 ) along the carriage assembly ( 72 ). Exposure control logic calculates a shuttle velocity according to index signal timing and adjusts the variable intensity of each exposure source ( 12 ) according to the shuttle velocity.
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