A focused line identifier is useful in a bar code reader employing Scheimpflug optics for focusing an illuminated line from the bar code on a two dimensional array of photodetectors. One line or a small group of lines somewhere on the array is the sharpest focus of a bar code within the working range...http://www.google.com.au/patents/US4963756?utm_source=gb-gplus-sharePatent US4963756 - Focused line identifier for a bar code reader
