Optical reader fluorescence control
First Claim
Patent Images
1. In an automatic reader of information recorded on a document in fluorescent ink where the document is propelled at high speed past a reading station, the combination which comprises:
- means to excite said ink at said read station with radiation in a first pass band of excitation energy in the blue portion of the electromagnetic spectrum;
a light sensitive detector at said read station; and
means for optically focusing light in a second pass band in the visible red portion of the electromagnetic spectrum emanating from said ink onto said detector, said second pass band separate from the first pass band of said blue portion.
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Abstract
A method and system for improving the signal-to-noise ratio in an automatic electro-optical reader of bar codes, wherein fluorescent ink bars arranged in coded configurations on a document are excited by a narrow band of visible radiation in the blue region of the electromagnetic spectrum, and an adjacent but not overlapping visible red region of the spectrum emanating from the ink bars is optically focused onto a light sensitive detector.
30 Citations
16 Claims
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1. In an automatic reader of information recorded on a document in fluorescent ink where the document is propelled at high speed past a reading station, the combination which comprises:
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means to excite said ink at said read station with radiation in a first pass band of excitation energy in the blue portion of the electromagnetic spectrum; a light sensitive detector at said read station; and means for optically focusing light in a second pass band in the visible red portion of the electromagnetic spectrum emanating from said ink onto said detector, said second pass band separate from the first pass band of said blue portion. - View Dependent Claims (2, 3, 4, 5)
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6. A method of improving the signal-to-noise ratio in an automatic, electro-optical reader of bar codes recorded on a document in a flourescent ink, which comprises:
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a. applying electromagnetic radiation to said document to excite fluorescent substances in said ink; b. restricting wavelengths of excitation radiation to those within a first pass band in the visible blue region of the electromagnetic spectrum adjacent to but not overlapping the visible red region having a longer wavelength; and c. optically passing all radiation emanating from said ink in a second band pass in said red region separate from the first pass band in said blue region.
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7. A system for minimizing the effect of background emissions in an automatic, electrooptical reader of fluorescent ink codes, which comprises:
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a. a radiation source; b. a first optical band-pass means interposed between said source and a reader station for focusing radiation in a first pass band of excitation energy in the blue portion of the electromagnetic spectrum upon ink codes to be read; c. a light sensitive detector; and d. a second optical band-pass means located between said reader station and said detector for focusing energy in a second pass band in the visible red portion of the electromagnetic spectrum emanating from the ink codes at said reader station onto said detector. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15)
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16. In an automatic reader of information recorded on a document in fluorescent ink where the document is propelled at high speed past a reading station, the combination which comprises:
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a light sensitive detector optically focused to respond to light emanating from said ink at said read station in the visible red portion of the electromagnetic spectrum centered about 600 millimicrons wavelength; and means to excite said ink at said read station with radiation in a narrow visible band in the blue electromagnetic spectrum centered at about 470 millimicrons and immediately below said red portion.
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Specification