DEVICE AND METHOD FOR MICROFILM IMAGING

摘要

A device for chemically capturing a microfilm image comprising a document viewing station (13), optical means, including a lens (18a, 18b), to project, via an optical path (14), an image of the document in the viewing station onto an image plane of the lens, means to chemically capture the image created in the image plane, means (26a, 26b) to alter the length of the optical path (14) to vary the reduction ratio occuring between document size and image size and autofocus means to act on the lens as the reduction ratio changes to maintain a well-focused image in the image plane. First means (11, 11) is provided to convey a document (10) through the viewing station (13), and a second means is provided to move the material capturing the image in the image plane during the image capturing process. A control device is provided to coordinate the first and second means to take account of the varying reduction ratio. Digital scanning can also be provided (at 80). The control system is to allow variable (several) values of document speed defined by the digital scanner capability at various resolutions and maintaining constant density film images at each speed during simultaneous digital and analogue scanning.