| 摘要 |
A printing apparatus (10) comprises a plurality of ink distributor rolls (20) supported for rotation about their axes (48, 50, 52), a rotatable shaft (90), and a vibrating means (32) for reciprocating the rolls (20) axially in response to rotation of the shaft (90). The vibrating means (32) comprises a plurality of eccentric members (116) fixed to the shaft (90) for rotation with the shaft (90). Each of the eccentric members (116) applies an individual torque to the shaft (90) in response to axial movement of a respective one of the rolls (20) when the eccentric member (116) rotates with the shaft (90). The fixed positions of the eccentric members (116) relative to each other on the shaft (90) minimize the sum of the individual torques and the fluctuations in the sum of the individual torques during rotation of the eccentric members (116). The detrimental effects of the torques on the printed image are thereby minimized.
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