Bar code recognition apparatus

Claim 1

A bar code recognition apparatus, comprising: means for reading a width value of each of four bars of two kinds presented alternately on a medium, to represent one character; memory means connected to said reading means for storing said width values of said four bars for each character read by said reading means; calculation means for calculating and producing two width values respectively smaller and greater than that of one of the two bars of a first kind, and two width values respectively smaller and greater than that of one of the two bars of a second kind; first comparison means, connected to said memory means and said calculation means, for comparing said smaller and greater width values of the bar of the first kind with the width value of the other bar of the first kind and for generating, according to the result of the comparison, a first, a second, or a third width value amplitude comparison signal for the first kind of bars, said first width value amplitude comparison signal being generated when said width value signal for a read individual bar is a width value signal indicative of a still greater width than said greater width provided by said calculation means, said second width value amplitude comparison signal being generated when said width value signal for a read individual bar is a width value signal indicative of a still smaller width than said smaller width provided by said calculation means, said third width value amplitude comparison signal being generated when said width value signal for a read individual bar is a width value signal indicative of a width intermediate between said greater and said smaller widths provided by said calculation means; second comparison means, connected to said memory means and said calculation means, for comparing the smaller and greater width values of the bar of the second kind with the width value of the other bar of the second kind, and for generating, according to the result of the comparison, the first, the second, or the third width value amplitude comparison signals for the second kind of bars; decoding means connected to said first and said second comparison means for combining said width value amplitude comparison signals produced from said first comparison means with said width value amplitude comparison signals produced from said second comparison means to produce nine combination signals of said width value amplitude comparison signals; ratio calculation means connected to said memory ans for calculating a ratio value from the width values of said read individual bars read out from said memory means; and means, connected to said decoding means and said ratio calculation means, for determining a corresponding character on a basis of one of said combination signals of said width value amplitude comparison signals derived from said decoding means and said ratio value of various width values calculated by said ratio calculation means.