Fast response scanner for photocopier - has separate scan motor with phase lock to copy drive

摘要

The fast response scanner is for a photocopier and scans the document line by line and projects the image strips onto the moving photosensitive layer (2). The copier and the scanner have separate electric drive motors (17,22) with shaft speeds which are monitored by impulse generators (19,25), with the impulse signals processed and used in a phase loop control to synchronise the speeds. The separate scan drive allows a rapid synchronisation of the scan and drive speeds with no sudden mechanical torque shock for the scanner. The control circuit incorporates a frequency detector and a phase shift amplifier to generate the correction signals for the scan drive. The phase control is switched off for the return path of the scanner.