A pen-type bar code reader uses a reflector formed on a concave lens surface of a convex lens system with respect to a bar code detector, except a region for transmitting a light flux. The convex lens system is mounted so that its optical axis is angled with respect to the light flux from the detector,...http://www.google.co.uk/patents/US4682016?utm_source=gb-gplus-sharePatent US4682016 - Pen-type bar code reader
