Apparatus for selecting originals for copying

US4251157A · kind A · utility

Assignee

• AGFA-Gervaert AG · DE

Inventors

• Bernhard Knor · Munich, DE
• Bernd Payrhammer · Munich, DE
• Helmut Wahl · Linz, AT

Key dates

• Filing date: Jul 13, 1979
• Grant date: Feb 17, 1981
• Expiry date: Jul 13, 1999

Classification

• Technology area (CPC G): Physics
• CPC primary: G03B27/80
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A strip of negatives is transported over a slit extending transverse to transport, and the image of successive slit-like elements of each original is projected onto the row of photosensitive zones of a CCD image sensor unit. A photodetector also receives the image of each slit-like element, either simultaneously with the CCD image sensor unit or earlier at a more upstream location, and generates an output signal indicating the average transparency of the whole slit-like image element. The average-transparency signal is used to control the clocking frequency of the clock signal which drives the CCD image sensor unit, either by changing the clocking frequency for each read-out of the image sensor unit or by changing the clocking frequency once per original, in the latter case a peak detector circuit being used to ascertain the transparency of the maximum transparency slit-like element of each original. The CCD image sensor unit may be of the type whose clock signal identically establishes the read-out rate of the photosensitive zones of the CCD and the charge-accumulation interval thereof, or may be of the type whose clock signal establishes the charge-accumulation interval without e…