초록 ▼

A method and apparatus for reading and decoding one-dimensional (1D) bar code symbols. A 1D bar code symbol is imaged by an optical assembly which includes a cubic phase mask that causes the optical transfer function of the optical assembly to remain approximately constant over a range of distances

A method and apparatus for reading and decoding one-dimensional (1D) bar code symbols. A 1D bar code symbol is imaged by an optical assembly which includes a cubic phase mask that causes the optical transfer function of the optical assembly to remain approximately constant over a range of distances between the apparatus and the symbol to be read. An electrical representation of the resulting image is converted to a smoothly varying analog image signal. A transition identifying circuit processes the analog image signal, without first applying a recovery function that takes into account the effect of the phase mask, and generates a binary signal which is used to decode the symbol.

대표청구항 ▼

[ What is claimed is:] [1.] An apparatus for optically reading and decoding data encoded in a linear bar code symbol that includes a plurality of data transitions, including, in combination:a. an optical assembly for forming an image of said symbol, said optical assembly including a phase mask for c

[ What is claimed is:] [1.] An apparatus for optically reading and decoding data encoded in a linear bar code symbol that includes a plurality of data transitions, including, in combination:a. an optical assembly for forming an image of said symbol, said optical assembly including a phase mask for causing the optical transfer function of said optical assembly to remain approximately constant over a range of distances between said apparatus and said symbol;b. an imaging device including a plurality of discrete photosensitive elements for receiving said image and converting said image into an image signal, said image signal being a stepwise continuous signal;c. transition identifying means responsive to said image signal for generating a digitized signal which provides data indicative of the locations of said transitions, without first applying to said image signal a recovery function that takes into account the effect of said phase mask, said transition identifying means including a low pass filter for approximately filtering out the steps of said stepwise continuous signal; andd. decoding means for decoding said data from said digitized signal.