| 摘要 |
<p>A servo controlled film drive for an automatic microfilm camera wherein the rotation of the metering roller (44) of the film drive is electronically synchronized to the rotation of the drive rollers (20) of the document transport. The film drive is powered by a DC motor (36), while the document transport is powered by an AC motor (12) (main drive motor). The variable speed film drive is computer programmable and uses phase-locked loop control circuits and optical (18, 48) incremental shaft encoders to maintain precise synchronization between the metering roller and the drive rollers at a predetermined ratio. The angular motion of the metering roller relative to the angular motion of the drive rollers is directly proportional to the linear velocity of the film relative to the linear velocity of the document in the transport. This relationship is directly proportional to the reduction ratio of the microfilm camera.</p> |
