Synchronising image transfer cylinders - uses sensors detecting peripheral markings to produce signals controlling rotational speeds

摘要

The image transfer system comprises a number of transfer cylinders (1-3) which are to be driven synchronously. Each cylinder carries markings (10-12) around its periphery which are detected by a sensor (13-15) which produces signals in response to the passing markings. The signals represent the angular position of that cylinder relative to a reference and are fed into a control circuit (16) which adjusts (7-9) the drive (4-6) of one or more cylinders so as to correct any deviation from their desired relative angular posn. The markings may have binary characteristics and may be arranged in axially adjacent peripheral series, each acting on its own detector, so that, at any moment, a number of simultaneous signals is produced by each sensor which together represent a multi-bit code.