06042012 is referenced by 123 patents and cites 65 patents.

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.

Title
Method and apparatus for reading images without need for self-generated illumination source
Application Number
363258
Publication Number
6042012
Application Date
September 28, 1998
Publication Date
March 28, 2000
Inventor
Randy L Person
Eugene
OR, US
Alexander M McQueen
Eugene
OR, US
Jon P C Williams
Eugene
OR, US
Paul R Huss
Eugene
OR, US
James W Ring
Eugene
OR, US
Jorge L Acosta
Eugene
OR, US
Bruce E Paris
Eugene
OR, US
Michael J Ahten
Eugene
OR, US
Bryan L Olmstead
Eugene
OR, US
Agent
Lyon & Lyon
Assignee
Spectra Physics Scanning Systems
OR, US
IPC
G06K 7/10
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