Bar-code reader
AssigneesFujitsu Limited, Fujitsu Frontech Limited
InventorsHideo Miyazawa, Isao Iwaguchi, Mitsuo Watanabe, Kozo Yamazaki, Masanori Ohkawa
Life of this patent
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Abstract
An extractor extracts a part that is apparently a bar-code signal from a signal that is subjected to opto-electric conversion. A narrow-band differential processor forms a waveform of an edge by differentiating by using a module frequency. The module point extractor extracts the module point from the waveform. The maximum likelihood judgment processor 5f performs ternarizing based on a maximum likelihood method by using broader information.
Claims18
A bar-code reader that acquires a signal strength of a reflected light that is reflected from black bars and white bars that form a bar code, extracts edge data that changes the signal strength from a black bar to a white bar and vice versa, ternarizes the edge data that is extracted, and decodes bar-code characters by using a result of the ternarizing, comprising:
- an amplitude acquiring unit that acquires an amplitude of each module point of the edge data based on a module frequency of the edge data;
- and
- a ternarizing processor that ternarizes the amplitude of the module point by a maximum likelihood method by using amplitudes of a module point and a plurality of module points that are in continuation with the module point.
A method of reading a bar code in which a signal strength of a reflected light that is reflected from black bars and white bars that form a bar code is acquired, edge data that changes the signal strength from a black bar to a white bar and vice versa, is extracted, the edge data that is extracted is ternarized, and bar-code characters are decoded by using a result of the ternarizing, comprising:
- acquiring an amplitude of each module point of the edge data based on a module frequency of the edge data;
- and
- ternarizing the amplitude of the module point by a maximum likelihood method by using amplitudes of a module point and a plurality of module points that are in continuation with the module point.
A bar-code reading computer program that includes a plurality of computer readable instructions that control a bar-code reader that acquires a signal strength of a reflected light that is reflected from black bars and white bars that form a bar code, extracts edge data that changes the signal strength from a black bar to a white bar and vice versa, ternarizes the edge data that is extracted, and decodes bar-code characters by using a result of the ternarizing, wherein the instructions, when executed by the computer, cause the computer to perform:
- acquiring an amplitude of each module point of the edge data based on a module frequency of the edge data;
- and
- ternarizing the amplitude of the module point by a maximum likelihood method by using amplitudes of a module point and a plurality of module points that are in continuation with the module point.
Dependencies are inferred from the claim text.