Document copier using laser beam - uses moving copy material with thermosensitive layer on plastics support and upper protective film

摘要

A document copying system uses a copy material consisting of a plastics sheet treated with a thermosensitive layer and covered with a protective plastics film which may be thermowelded on, or covered by a varnish. The original document is then scanned by an optical scanning device and an electronic circuit which responds to the brightness of the surface, and which controls a laser beam with a modulated power which forms a point writing device which acts on the thermosensitive layer to change its colour, as the copy material is moved past.