Verfahren und System zum Lesen von Bildern ohne Erfordernis einer eigenen Beleuchtungsquelle und Barcodeleser hierfür

• Main Authors: AHTEN, MICHAEL J, RING, JAMES W, OLMSTEAD, BRYAN L, PERSON, RANDY L, WILLIAMS, JON P.C, HUSS, PAUL R, PARIS, BRUCE E, MCQUEEN, ALEXANDER M, ACOSTA, JORGE L
• Format: Patent
• Language: German
• Published: 11.10.2007
• Subjects: CALCULATING; COMPUTING; COUNTING; HANDLING RECORD CARRIERS; PHYSICS; PRESENTATION OF DATA; RECOGNITION OF DATA; RECORD CARRIERS

A method and apparatus for reading bar codes or other images while reducing or eliminating the need for self-generated illumination. An image reader is preferably embodied as a handheld unit and comprises an efficient optical collection system including an aperture with a high aspect ratio and/or a multi-focal lens or lenses. An optically transmissive spacer affixed to the front of the handheld unit allows ambient light to be collected at close range, and a diffuser may be used to reflect ambient light from the handheld unit to provide additional illumination at close range. A masked CCD detector with rectangular pixels receives collected light and is coupled to an adaptive exposure circuit for preventing saturation of the CCD detector at high illumination levels. A correlated double sampling circuit coupled to the adaptive exposure circuit rejects common mode noise and allows operation in lower light levels. The correlated double sampling circuit is connected to a signal processor which uses a derivative based technique for detecting edges of the image. A decoder uses the edge detection information to decode encoded information from the image.