Bar-code reader device

Claim 1

A bar-code reader comprising: an image sensor for producing an output signal in response to light incident on said image sensor; light emission means for projecting a light beam onto a bar code label, said bar code label having a bar code symbol, to effect a scanning across the bar code symbol; light reception means for focusing a portion of the light beam which is reflected from the bar code label onto said image sensor; signal processing means for processing the output signal of said image sensor to generate processed data; memory means for storing said processed data provided by said signal processing means in a serial manner in synchronism with the scanning across the bar code symbol and for storing a two-dimensional array of pixels, having a start address, representing an image of said bar code symbol, said image of said bar code symbol having a plurality of edges including first edge which is closest to said start address; extraction means for extracting said image of said bar code symbol from said memory means, said extraction means comprising (i) means for reading said two-dimensional array of pixels beginning at said start address to detect said first edge and (ii) means for tracing said edges beginning with said first edge and for detecting corner points of said image which are defined by said edges, whereby a location of said image of said bar code symbol in said two-dimensional array of pixels is determined; and decoding means for decoding the image of the bar code symbol extracted by said extraction means, said decoding means comprising (i) means for detecting a start pattern and a stop pattern in said image, determining a shortest line between said start pattern and said stop pattern, and scanning said image along said shortest line to obtain a first scan result and (ii) stage counting means for determining a number of stages of said bar code symbol, wherein said stage counting means comprises means for scanning said image along a line extending diagonally across said image between two of said corner points to obtain a second scan result, comparing said first scan result to said second scan result and, if said first scan result and said second scan result agree, determining that said bar code symbol is a one-dimensional bar code symbol.