System and method for decoding and encoding compensated optical codes

• US 7,299,989 B2
• Filed: 10/28/2004
• Issued: 11/27/2007
• Est. Priority Date: 12/15/2000
• Status: Expired due to Term

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Schuessler, Frederick
• Primary Examiner(s): Caputo, Lisa
• Assistant Examiner(s): Labaze, Edwyn
• Application Number:
  US10/975,880
• Publication Number:
  US 20050092840A1
• Time in Patent Office: 1,125 Days
• Field of Search: 235/484, 235/463, 23546201-46202, 235/462.49, 235/462.07, 235/462.12, 235/494
• US Class Current: 235/484
• CPC Class Codes: G06K 19/06028 using bar codes

Abstract

An optical code reader system is provided for reading a presented optical code having first and second sets of elements, the first set of elements including a plurality of elements having a first reflective property and the second set of elements including a plurality of elements having a second reflective property. The system includes a photo sensor module which senses incident light reflected from the presented optical code and generates electrical signals corresponding to the sensing. The system further includes a software decoder module executable on a processor for uncompensating the presented optical code by adjusting a relative measured dimension of individual elements of the first set of elements in accordance with a predetermined adjustment factor for uncompensating the first set of elements without uncompensating the second set of elements for generating an uncompensated optical code.

Claims

1. An optical code reader system for reading a presented optical code having first and second sets of elements, the first set of elements including a plurality of elements having a first reflective property and the second set of elements including a plurality of elements having a second reflective property, the system comprising:

a photo sensor module for sensing incident light reflected from the presented optical code and generating electrical signals corresponding to the sensing; and

a decoder module includes software instructions executable on at least one processor for providing for processing the electrical signals for performing an algorithm including the steps of;

providing for uncompensating the presented optical code by adjusting a relative measured dimension of individual elements of the first set of elements in accordance with a predetermined adjustment factor for uncompensating the first set of elements without uncompensating the second set of elements for generating an uncompensated optical code; and

providing for decoding the uncompensated optical code.

2. The system according to claim 1, wherein at least a portion of the plurality of elements having the first reflectivity property and the plurality of elements having the second reflectivity property are produced by at least one of removing, depositing and deforming material so as to vary optical contrast of a surface, projecting, displaying on a display device, and a combination thereof.

3. The system according to claim 1, wherein the providing for uncompensating step further includes the step of:

providing for determining a T distance for a sequence of respective pairs of an adjacent element having the first reflectivity property and an element having the second reflectivity property normalized against a sum of the measured dimensions of respective elements forming a symbol character;

providing for determining a series of terms of a T sequence;

providing for modifying the T sequence by subtracting the predetermined adjustment factor from each term of the T sequence; and

decoding the modified T sequence.

4. The system according to claim 1, wherein the algorithm further comprises the step of providing for processing at least a portion of the presented optical code for determining the predetermined adjustment factor.

5. The system according to claim 1, wherein the presented optical code is encoded by an n,k bar code encodation scheme, wherein the predetermined adjustment factor is a function of a module width of an element for a bar code of the presented optical code.

6. The system according to claim 1, wherein the algorithm further includes the step of providing for discriminating between a presented optical code that is compensated and a presented optical code that is not compensated.

7. The system according to claim 6, wherein the providing for uncompensating step is performed on a presented optical code that is compensated, but not on a presented optical code that is not compensated.

8. The system according to claim 6, wherein the providing for discriminating step includes the step of providing for recognizing a pattern included in the plurality of elements having the first reflectivity property and the plurality of elements having the second reflectivity property which indicates that the presented optical code is a compensated optical code.

9. The system according to claim 6, wherein the presented optical code further includes at least one of a start and stop pattern;

and

wherein the providing for discriminating step includes the step of providing for recognizing a pattern included in at least one of the start and start pattern which indicates that the presented optical code is a compensated optical code.

10. A computer readable medium storing a set of programmable instructions configured for execution by at least one processor for reading a presented optical code having first and second sets of elements, the first set of elements including a plurality of elements having a first reflective property and the second set of elements including a plurality of elements having a second reflective property, the programmable instructions comprising:

means for providing for uncompensating the presented optical code by adjusting a relative measured dimension of individual elements of the first set of elements in accordance with a predetermined adjustment factor for uncompensating the first set of elements without uncompensating the second set of elements for generating an uncompensated optical code.

11. The system according to claim 10, wherein the existing optical code encodation scheme is an n,k bar code encodation scheme.

12. A system for generating compensated optical codes comprising:

a processor assembly having least one processor;

a compensator module executable on the at least one processor for performing an algorithm comprising the steps of;

providing for receiving data associated with an uncompensated optical code encoded in accordance with an encodation scheme including a pattern of representations of first and second sets of elements, the first set of elements including a plurality of elements having a first reflectivity property and the second set of elements including a plurality of elements having a second reflectivity property; and

providing for generating data representing a compensated optical code having a pattern of representations of first and second sets of elements, the first set of elements including a plurality of elements having the first reflectivity property and the second set of elements including a plurality of elements having the second reflectivity property, wherein the pattern of the compensated optical code is substantially the same as the pattern of the uncompensated optical code, except that representations of a dimension of individual elements of the first set of elements is adjusted in accordance with a predetermined adjustment factor for compensating the representations of the first set of elements without compensating the representations of the second set of elements.

13. The system according to claim 12, wherein:

the received data includes data to be encoded into a representation of the uncompensated optical code; and

the algorithm further comprises the step of providing for encoding the data into the representation of the uncompensated optical code.

14. The system according to claim 12, wherein:

the received data includes a representation of the uncompensated optical code; and

the algorithm further comprises the step of providing for determining the pattern of the representations of the first and second sets of elements.

15. The system according to claim 12, wherein at least a portion of the plurality of elements having the first reflectivity property and the plurality of elements having the second reflectivity property are produced by at least one of removing, depositing and deforming material so as to vary optical contrast of a surface, projecting, displaying on a display device, and a combination thereof.

16. The system according to claim 12, wherein the compensator module algorithm further includes the step of providing an auto-discrimination feature in the compensated optical code indicating that the optical code is compensated.

17. The system according to claim 16, wherein the auto-discrimination feature includes the magnitude of the predetermined adjustment factor.

18. The system according to claim 17, wherein the predetermined adjustment factor is a function of a module width of respective elements for a bar code of the uncompensated optical code.

19. A computer readable medium storing a set of programmable instructions configured for execution by at least one processor for generating a compensated optical code, the programmable instructions comprising:

means for providing for receiving data associated with an uncompensated optical code encoded in accordance with an encodation scheme including a pattern of representations of first and second sets of elements, the first set of elements including a plurality of elements having a first reflectivity property and the second set of elements including a plurality of elements having a second reflectivity property; and

means for providing for generating data representing a compensated optical code having a pattern of representations of first and second sets of elements, the first set of elements including a plurality of elements having the first reflectivity property and the second set of elements including a plurality of elements having the second reflectivity property, wherein the pattern of the compensated optical code is substantially the same as the pattern of the uncompensated optical code, except that representations of a dimension of individual elements of the first set of elements is adjusted in accordance with a predetermined adjustment factor for compensating the representations of the first set of elements without compensating the representations of the second set of elements.

20. A compensated n, k bar code symbology comprising characters having k bars and k spaces having a respective dimension that varies, the dimension of each bar being from 1 to m modules, the dimension of each space being from 1+x to m+x modules 0<

×

≦

2, and wherein the overall dimension of each character is n+kx modules.

21. The compensated symbology according to claim 20, wherein at least a portion of the bars and spaces are produced by at least one of removing, depositing and deforming material so as to vary optical contrast of a surface, projecting, displaying on a display device, and a combination thereof.

22. An uncompensated bar code symbology and related compensated symbology;

the uncompensated bar code symbology comprising a set of uncompensated patterns of first and second elements having first and second reflectivity properties, respectively, each uncompensated pattern encoding a respective value, a respective dimension of each first and second element being from 1 to m modules; and

the compensated symbology comprising a set of compensated patterns of first and second elements having first and second reflectivity properties, respectively, each compensated pattern encoding a respective value and corresponding to an uncompensated pattern encoding the respective value, the respective dimensions of the second elements in the compensated pattern equaling the respective dimensions of the corresponding second elements in the corresponding uncompensated pattern, the respective dimensions of the first elements in the compensated pattern equaling the respective dimensions of the corresponding first elements in the corresponding uncompensated pattern value plus x modules, x>

0.

23. The symbology according to claim 22, wherein at least a portion of the first and second elements of the compensated code and the uncompensated code are presented by at least one of removing, depositing and deforming material so as to vary optical contrast of a surface, projecting, displaying on a display device, and a combination thereof.