Claims
- 1. An optical reader for generating an outgoing light beam to illuminate an information symbol comprising regions of different light reflectivity, and for collecting an incoming light beam reflected from the symbol, the reader comprising:
a source of the outgoing light beam; light collection optics for collecting the incoming light beam and for directing the incoming light beam to a multi-channel photodetector; the multi-channel photodetector comprising an array of more than one individual active optical sensing element, each said element having an output capable of providing an output signal representative of light impinging thereon; the output of each detection element being coupled to a respective channel for processing the output signal of a respective detection element.
- 2. An optical reader according to claim 1, wherein one of the active optical sensing elements is positioned around another of the active optical sensing elements.
- 3. An optical reader according to claim 2, wherein the outgoing light beam, light collection optics, and array of sensing elements are configured so that the output of a first group of the sensing elements corresponds to a spot of a first size passing across the information symbol, and so that the output of a second group of the sensing elements corresponds to a spot of second size, larger than said first size, passing across the information symbol.
- 4. An optical reader according to claim 3, wherein the array of sensing elements comprises a first and a second sensing element, and wherein the first sensing element is contained within the first group and the first and the second elements are contained within the second group.
- 5. An optical reader according to claim 4, wherein the first group contains only the first sensing element, and the second group contains only the first and second sensing elements.
- 6. A reader for reading printed indicia, for example bar code symbols, comprising a light source for illuminating an indicia and a light detector for producing a signal corresponding to detected light reflected from the indicia, the light detector having a plurality of channels, each channel being associated with a different resolution level of the signal produced by the detector.
- 7. A reader as claimed in claim 6 in which the detector is arranged to process the signal and transfer a signal processed at a first threshold level via a first channel and a signal processed at a second resolution level via a second channel.
- 8. A reader as claimed in claim 6 in which the light source is arranged to generate a first illuminating beam at a first resolution and a second illuminating beam at a second resolution, the first and second illuminating beams being spatially separated, and the detector comprises a first region associated with a first channel for producing a signal corresponding to the first beam and a second region associated with a second channel for producing a signal corresponding to the second beam.
- 9. A reader as claimed in claim 8 in which the light source is arranged to generate a first and second illuminating beam spaced laterally from one another.
- 10. A reader as claimed in claim 9 in which the detecting regions of the detector corresponding to the first and second beams are laterally spaced from one another.
- 11. A reader as claimed in claim 8 in which the light source is arranged to generate concentric first and second illuminating beams.
- 12. A reader as claimed in claim 11 in which the detecting regions of the detector corresponding to the first and second beams are concentric.
- 13. A reader as claimed in claim 6 in which the light source is arranged to generate a light beam of a first resolution at a first wavelength and a light beam of a second resolution at a second wavelength.
- 14. A reader as claimed in claim 13 in which the detector is arranged to detect light of the first wavelength and produce a signal corresponding to the first light beam at a first channel and to detect light of the second wavelength and produce a signal corresponding to the light of the second wavelength at a second channel.
- 15. A reader as claimed in claim 6 in which the light source is arranged to generate a light beam at a first resolution in a first set of pulses and a light beam at a second resolution in a second set of pulses temporally off-set from the first set of pulses.
- 16. A reader as claimed in claim 15 in which the detector is synchronised with the light source to detect light pulses of the first resolution and produce corresponding signals at a first channel and to detect the light pulses of the second resolution and produce corresponding signals at a second channel.
- 17. A reader as claimed in claim 6 comprising a flying spot scanning reader.
- 18. A reader as claimed in claim 6 comprising a field of view optical reader.
- 19. A reader as claimed in claim 6 including a decoder arranged to analyse the signal from a channel to determine whether it is a valid signal.
- 20. A reader as claimed in claim 19 in which the decoder is arranged to merge the signals from each channel if no valid signal from an individual channel is detected.
- 21. A reader for reading printed indicia comprising a light source for illuminating an indicia and a light detector for detecting light reflected from the indicia wherein the detector comprises a first region and a second region for detecting reflected light at a first resolution level and a second resolution level respectively, a first channel being associated with the first region and a second channel being associated with the second region.
- 22. A method of operation of a reader for reading printed indicia comprising a light source for illuminating the indicia and a light detector producing a signal corresponding to detected light reflected from the indicia, a first channel and a second channel being associated with the detector for carrying respective signals at different resolution levels, and a decoder; including the steps of decoding the signal from the first channel and, if that signal is not valid, decoding the signal from the second channel and, if that is not valid, merging the signals from the first and second channels, decoding the merged signal and selecting the valid portions of the merged signal.
- 23. A reader for reading printed indicia such as bar code symbols comprising a light source for illuminating an indicia and a detector for producing a signal corresponding to detected light reflected from the indicia, a first channel and a second channel being arranged to receive signals processed by the detector wherein the second channel includes buffer means for delaying a signal and merging the signal with a subsequent signal transferred by the first channel.
- 24. A reader as claimed in claim 23 in which an indicia is scanned at intervals T giving rise to a signal to the first and second channels via the detector, and the buffer means of the second channel is arranged to delay the signal for the period T in order to merge the signal with the subsequent signal transferred by the first channel.
- 25. A method of processing analog signals corresponding to a light beam reflected from a printed indicia including receiving the light beam at a detector, converting the light beam to a digital signal and transferring the digital signal via a first channel to a decoder, transferring the digital signal from the detector via a second channel to a delay buffer and merging the delayed signal with a subsequent signal transferred by the first channel.
- 26. A method of decoding a bar code symbol composed of elements of different reflectivity comprising scanning the bar code symbol with a light beam, detecting the reflected light beam and providing a digitized signal carrying the bar code information, wherein the decoder compares the width of each element of a first reflectivity with the width of another element of that reflectivity in the bar code symbol and identifies the element as a defect if its width is less than a predetermined proportion of the width of the other element.
- 27. A method as claimed in claim 26 in which the predetermined proportion is 60%.
- 28. A method as claimed in claim 26 in which, if the element is identified as a defect its width is added to the width of the elements on either side of the space.
- 29. A method as claimed in claim 26 in which the element is compared with neighbouring elements of the same reflectivity.
- 30. A processor for processing an optical signal received from a printed indicia, the processor including a detector, a first channel and a second channel associated with a detector and a decoder wherein the channels are arranged to transfer signals at different resolution levels from the detector to the decoder.
REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of Ser. No. 08/314,519, filed Sep. 28, 1994, now U.S. Pat. No. ______, which was a division of Ser. No. 08/109,021, filed Aug. 19, 1993, now U.S. Pat. No. 5,352,922, which was a division of Ser. No. 07/735,573 filed Jul. 25, 1991, now U.S. Pat. No. 5,278,397.
Divisions (4)
|
Number |
Date |
Country |
Parent |
09759937 |
Jan 2001 |
US |
Child |
10184856 |
Jun 2002 |
US |
Parent |
08598928 |
Feb 1996 |
US |
Child |
09759937 |
Jan 2001 |
US |
Parent |
08109021 |
Aug 1993 |
US |
Child |
08314519 |
Sep 1994 |
US |
Parent |
07735573 |
Jul 1991 |
US |
Child |
08109021 |
Aug 1993 |
US |
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
08314519 |
Sep 1994 |
US |
Child |
08598928 |
Feb 1996 |
US |