Code reading systems
First Claim
1. A method for reading a fluorescent code on the surface of an article comprising the steps of:
- directing radiation toward the code to cause the code to fluoresce, the radiation being modulated at two frequencies, which frequencies are non-harmonically related; and
detecting a radiation signal resulting from fluorescence of the code, which radiation signal is of a frequency that is one of a sum of the two frequencies and the difference of the two frequencies.
4 Assignments
0 Petitions
Accused Products
Abstract
Bar code reading systems having enhanced detection capabilities are disclosed. The systems are particularly useful for invisible bar codes. The bar code is irradiated with radiation that is sine wave or square wave modulated at one or more frequencies. A detector is sensitive to a frequency related to the modulation frequencies, preferable to a sum or a difference of at least two modulating frequencies, produced by intermodulation of the modulating frequencies. Such intermodulation can result from the non-linear fluorescing characteristics of dyes incorporated into the bar code markings. The modulation can also be sinusoid or square wave at a single frequency. Detection of coded information on sheets containing whiteners or other dyes capable of fluorescing in response to the radiation utilized by the code reader is improved by employing radiation absorbing components in the code markings.
104 Citations
33 Claims
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1. A method for reading a fluorescent code on the surface of an article comprising the steps of:
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directing radiation toward the code to cause the code to fluoresce, the radiation being modulated at two frequencies, which frequencies are non-harmonically related; and detecting a radiation signal resulting from fluorescence of the code, which radiation signal is of a frequency that is one of a sum of the two frequencies and the difference of the two frequencies. - View Dependent Claims (2, 3, 4)
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5. Apparatus for reading bar codes formed of fluorescing marking material disposed on the surface of an article comprising:
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a radiation source for emitting a beam of radiation; modulating means for modulating the beam of radiation at two frequencies that are not harmonically related; means for irradiating the bar code with the modulated beam; detecting means for detecting a fluorescent radiation signal from the bar code at a frequency that is one of a sum of the two frequencies and a difference of the two frequencies. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A system for reading coded information disposed on a surface of an object, comprising:
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a radiation source for directing incident radiation toward the coded information on said surface; modulating means for modulating said incident radiation at a predetermined frequency; means for receiving radiation from the coded information, the received radiation emitted from the surface in response to impingement of said incident radiation on said surface; and detector means for selectively detecting emitted radiation, having a frequency related to said predetermined frequency, wherein the frequency component is an harmonic of said predetermined frequency.
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20. A system for reading coded information disposed on a surface of an object, comprising:
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a radiation source for directing incident radiation toward the coded information on said surface; modulating means for modulating said incident radiation at a predetermined frequency; means for receiving radiation from the coded information, the receivid radiation emitted from the surface in response to impingement of said incident radiation on said surface; and detector means for selectively detecting emitted radiation, having a frequency component related to said predetermined frequency, wherein the coded information is a pattern formed of a marking material disposed on said surface, said marking material including a dye for absorbing said incident radiation and emitting said emitted radiation in response thereto. - View Dependent Claims (21, 22)
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23. A system for reading coded information disposed on a surface of an object, comprising:
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a radiation source for directing incident radiation toward the coded information on said surface; modulating means for modulating said incident radiation at a predetermined frequency; means for receiving radiation from the coded information, the received radiation emitted from the surface in response to impingement of said incident radiation on said surface; and detector means for selectively detecting emitted radiation, having a frequency component related to said predetermined frequency, wherein the modulating means further comprises means for modulating the incident radiation at a second frequency non-harmonically related to the predetermined frequency and wherein the detector means is responsive to radiation that is modulated at one of a sum and a difference of the predetermined frequency and the second frequency. - View Dependent Claims (24, 25)
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26. A method for reading coded information disposed on a surface, comprising the steps of:
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directing incident radiation toward the coded information on the surface; modulating said incident radiation at a predetermined frequency; receiving radiation emitted from the coded information on the surface in response to incident radiation; and selectively detecting a component of the received radiation at a frequency related to said predetermined frequency, wherein the component of the received radiation is modulated at a frequency which is a harmonic of the predetermined frequency.
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27. A method for reading coded information disposed on a surface, comprising the steps of:
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directing incident radiation toward the coded information on the surface; modulating said incident radiation at a predetermined frequency; receiving radiation emitted from the coded information on the surface in response to incident radiation; and selectively detecting a component of the received radiation at a frequency related to said predetermined frequency, wherein the step of modulating said incident radiation further comprises modulating the incident radiation at a second frequency non-harmonically related to the predetermined frequency and the step of detecting the component of the emitted radiation comprises detecting one of a sum component and a difference component of the predetermined frequency and the second frequency. - View Dependent Claims (28, 29)
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30. A reader for sensing coded information applied to a surface comprising:
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a source of radiation for emitting a beam of radiation; an optical deflector for receiving said beam in one direction and deflecting the beam of radiation toward the surface in a second direction transverse to the first direction; a detecting element positioned to receive radiation from the surface, the radiation from the surface passing through the optical deflector to the detecting element. - View Dependent Claims (31, 32, 33)
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Specification