An image reader that reads the image on transmission-type originals such as negative reversal films for use on digital photoprinters, for example, and which has an inexpensive and simple construction and yet is capable of efficient and rapid image reading operations. The time of reading the light passing...http://www.google.de/patents/US5568270?utm_source=gb-gplus-sharePatent US5568270 - Image reading apparatus which varies reading time according to image density
