초록 ▼

A method and apparatus are provided for reading bar codes or other images while reducing or eliminating the need for self-generated illumination. An image reader comprises an efficient optical collection system including an aperture with a high aspect ratio and/or a multi-focal lens or lenses. A CCD

A method and apparatus are provided for reading bar codes or other images while reducing or eliminating the need for self-generated illumination. An image reader comprises an efficient optical collection system including an aperture with a high aspect ratio and/or a multi-focal lens or lenses. A CCD detector receives collected light and is coupled to an adaptive exposure circuit for preventing saturation of a CCD detector at high illumination levels. A correlated double sampling circuit receives the output of the CCD detector to allow lower light levels to be detected by the system. The correlated double sampling circuit is connected to a signal processing block which uses a derivative based technique for enhanced edge detection. Edge detection information may be provided to a decoder for decoding. Various other embodiments may utilize some but not all of the above elements, or may include additional refinements, while obtaining the benefit of reducing or eliminating the need for self-generated illumination.

대표청구항 ▼

[ What is claimed is:] [1.] A bar code reader comprising:a light sensitive detector;a lens having a plurality of zones, at least two or said zones having different focal distances and at least partially overlapping depths of field, such that each zone simultaneously focuses light reflected from a ta

[ What is claimed is:] [1.] A bar code reader comprising:a light sensitive detector;a lens having a plurality of zones, at least two or said zones having different focal distances and at least partially overlapping depths of field, such that each zone simultaneously focuses light reflected from a target to be read onto said light sensitive detector;means for reducing, interference between said zones, said means comprising a compound aperture positioned between said lens and said target;a signal output from said light sensitive detector containing information corresponding to relatively light portions and darker portions of said target; anda decoder coupled to said light sensitive detector.