Sequenced illumination in mark reading devices

• US 9,582,697 B2
• Filed: 05/28/2013
• Issued: 02/28/2017
• Est. Priority Date: 05/28/2013
• Status: Active Grant

• Current Assignee: Sicpa Holding SA
• Original Assignee: Sicpa Holding SA
• Inventors: Molina, Aldric, Duca, Nicola
• Primary Examiner(s): Le, Thien M
• Assistant Examiner(s): TAYLOR, APRIL ALICIA
• Application Number:
  US14/894,058
• Publication Number:
  US 20160110576A1
• Time in Patent Office: 1,372 Days
• US Class Current: 1/1
• CPC Class Codes: G06K 19/06103 the marking being embedded in a human recognizable image, e.g. a company logo with an embedded two-dimensional code
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/1413 1D bar codes
• CPC Class Codes: G06K 7/1417 2D bar codes

Abstract

A reader operable to read a mark on a substrate, the reader comprising a power source, operable to deliver a variable drive current or voltage, a light source operable to illuminate said mark with a sequence of illumination light pulses of different wavelength spectra, an intensity of said illumination light pulses varying according to the delivered drive current or voltage, a light sensor operable to measure an intensity of light received from said mark and to deliver a corresponding light intensity signal, and a control unit operable to control said power source and light sensor to control timings of said illumination light pulses according to a switching pattern and timings to acquire said light intensity signal for synchronizing acquisition of said light intensity signal with said sequence of illumination light pulses, said control unit being further operable to adjust a duty cycle of said switching pattern so as to maintain heat generation associated to each illumination light pulse below a given threshold value.

Claims

1. A reader operable to read a mark on a substrate, the reader comprising:

a power source, operable to deliver a variable drive current or voltage,

a light source operable to illuminate said mark with a sequence of illumination light pulses of different wavelength spectra, an intensity of said illumination light pulses varying according to the delivered drive current or voltage;

a light sensor operable to measure an intensity of light received from said mark and to deliver a corresponding light intensity signal; and

a control unit operable to control said power source and light sensor to control timings of said illumination light pulses according to a switching pattern and timings to acquire said light intensity signal for synchronizing acquisition of said light intensity signal with said sequence of illumination light pulses,

said control unit being further operable to adjust a duty cycle of said switching pattern so as to maintain heat generation associated to each illumination light pulse below a given threshold value,

wherein the control unit is further configured to compute a decay time of a luminescent material of said mark based on said light intensity signal.

2. The reader of claim 1, wherein the light source comprises at least two component light sources, a first component light source operable to illuminate the mark with a light pulse of a first wavelength spectrum, and a second component light source operable to illuminate the mark with light pulse of a second wavelength spectrum.

3. The reader of claim 1, wherein said light sensor comprises an image acquisition unit configured for acquiring image data of the mark.

4. The reader of claim 3, wherein the control unit is configured to control an acquisition time of said image acquisition unit for controlling said timings to acquire said light intensity signal.

5. The reader of claim 4, wherein said acquisition time is an aperture opening time during which image data of the mark are acquired.

6. The reader of claim 1, wherein said decay time is computed also based on wavelength spectrum information related to the light received from the mark.

7. The reader of claim 1, wherein the mark comprises a luminescent material, and the control unit is configured to control said timings in accordance with emission characteristics of said luminescent material.

8. The reader of claim 1, wherein the mark comprises a plurality of luminescent materials, each having different emission characteristics, and the control unit is configured to control said timings in accordance with each emission characteristics of each luminescent material.

9. The reader of claim 1, wherein the control unit is configured to control any one of a delay between said timings, a position of one of said timings, and a duration of one of said light pulses.

10. The reader of claim 1, wherein said control unit adjusts the duty cycle of said switching pattern via a control loop.

11. The reader of claim 1, wherein said switching pattern is a switching waveform defining the switching on and off of said variable drive current or voltage.

12. The reader of claim 1, wherein the mark is any one of a one-dimensional barcode, a two-dimensional barcode, a datamatrix, and a security mark.

13. A method of operating a reader operable to read a mark on a substrate, the reader comprising:

a power source, operable to deliver a variable drive current or voltage,

a light source operable to illuminate said mark with a sequence of illumination light pulses of different wavelength spectra, an intensity of said illumination light pulses varying according to the delivered drive current or voltage;

a light sensor operable to measure an intensity of light received from said mark and to deliver a corresponding light intensity signal;

said method comprising;

controlling timings of said illumination light pulses according to a switching pattern and timings to acquire said light intensity signal for synchronizing acquisition of said light intensity signal with said sequence of illumination light pulses,

adjusting a duty cycle of said switching pattern so as to maintain heat generation associated to each illumination light pulse below a given threshold value, and

computing a decay time of a luminescent material of said mark based on said light intensity signal.

14. The method of claim 13, wherein the light source comprises at least two component light sources, a first component light source operable to illuminate the mark with a light pulse of a first wavelength spectrum, and a second component light source operable to illuminate the mark with light pulse of a second wavelength spectrum.

15. The method of claim 13, further comprising acquiring image data of the mark.

16. The method of claim 15, further comprising controlling an acquisition time of said acquiring the image data for controlling said timings to acquire said light intensity signal.

17. The method of claim 16, wherein said acquisition time is an aperture opening time during which image data of the mark are acquired.

18. The method of claim 13, wherein said decay time is computed also based on wavelength spectrum information related to the light received from the mark.

19. The method of claim 13, wherein the mark comprises a luminescent material, and the control unit is configured to control said timings in accordance with emission characteristics of said luminescent material.

20. The method of claim 13, wherein the mark comprises a plurality of luminescent materials, each having different emission characteristics, and the control unit is configured to control said timings in accordance with each emission characteristics of each luminescent material.

21. The method of claim 13, further comprising controlling any one of a delay between said timings, a position of one of said timings, and a duration of one of said light pulses.

22. The method of claim 13, further comprising adjusting the duty cycle of said switching pattern via a control loop.

23. The method of claim 13, wherein said switching pattern is a switching waveform defining the switching on and off of said variable drive current or voltage.

24. The method of claim 13, wherein the mark is any one of a one-dimensional barcode, a two-dimensional barcode, a datamatrix, and a security mark.

25. A computer program comprising code, said code, when being executed on a processing resource, implementing a method of claim 13.

26. A computer program product comprising a tangible data carrier storing in a non-volatile manner the computer program of claim 25.