A viewing device for X-ray films or the like automatically masks the areas of the viewing screen not in registry with the film to be viewed responsive to the insertion of a film. The device includes a dimension sensing mechanism which aligns a selected mask with a positioned film automatically in accordance...http://www.google.fr/patents/US4510708?utm_source=gb-gplus-shareBrevet US4510708 - Viewer for X-ray and like films
