Apparatus and method of encoding and decoding barcodes

• US 4,728,784 A
• Filed: 01/30/1987
• Issued: 03/01/1988
• Est. Priority Date: 01/30/1987
• Status: Expired due to Fees

• Current Assignee: Federal Express Corporation (FedEx Corporation)
• Original Assignee: Federal Express Corporation (FedEx Corporation)
• Inventors: Stewart, Stephen R.
• Primary Examiner(s): TRAFTON, DAVID
• Application Number:
  US07/009,203
• Time in Patent Office: 396 Days
• Field of Search: 235/436, 235/466, 235/462, 235/463, 235/487, 235/472
• US Class Current: 235/462.07
• CPC Class Codes: G06K 1/12 otherwise than by punching
• CPC Class Codes: G06K 19/06028 using bar codes
• CPC Class Codes: G06K 7/0166 by means of clock-signals derived from the code marks, e.g. self-clocking code

Abstract

A method and system for reading encoded information from conventional bar codes and from hand-encoded barcodes is provided. The method and system include processing which eliminates false spaces and bars in conventional pre-encoded printed barcode formats as well as those in hand-encoded barcode formats. A pre-printed barcode form containing a plurality of bars and spaces representing the elements of a character code is used in which at least one of the bars is designed to be modified by hand to represent the encoded character. A barcode reader system scans the barcode and processes the scanned barcode symbol into decoded form. A barcode label for encoding a multi-character string readable by a barcode reader is also provided which includes a plurality of data lines which contains barcode readable start and stop codes unique to each data line and a barcode readable digit form located between the start and stop code of each data line.

Claims

1. A method for reading encoded information from a barcode wherein the barcode includes bars and spaces comprising the elements of the barcode and each bar and space has a width, the method comprising the steps of:

reading the barcode using a barcode reader to capture data for forming a complete image timing sample of the barcode;

generating in a barcode processor the complete image timing sample from the data captured by the barcode reader, the complete image timing sample representing the read barcode including the number of elements in the barcode, whether the element is a space or a bar, and the width of each element; and

processing the complete image timing sample in the barcode processor, the processing step including the substeps of

identifying false elements in the complete image timing sample,

filtering the false elements from the complete image timing sample, and

processing the filtered complete image timing sample to decode the encoded information contained in the elements of the filtered complete image timing sample.

2. The method of claim 1 in which the substep of filtering the false elements from the complete image timing sample, each false element having a width, includes the following steps for each false element:

identifying in the barcode processor the element preceding the false element, the preceding element having a width;

identifying in the barcode processor the element following the false element, the following element having a width; and

combining in the barcode processor the width of the false element with the width of the preceding element and the width of the following element, thereby eliminating the false element by transforming it into a portion of the elements preceding and following the false element.

3. The method of claim 1 in which the substep of identifying false elements in the complete image timing sample, each false element having a width, further includes the steps of:

dividing the complete image timing sample into segments;

setting a filter threshold in the barcode processor for each segment of the complete image timing sample;

for each complete image timing sample segment comparing in the barcode processor the width of each element in the complete image timing sample segment with the filter threshold for that segment; and

identifying as a false element each element in the complete image timing sample segment having a width less than the filter threshold for that segment.

4. The method of claim 3 in which the step of setting the filter threshold for each segment includes the steps of:

determining in the barcode processor the total width of all the elements in the complete image timing sample segment; and

dividing the total width by a filter threshold factor for that segment.

5. The method of claim 1 in which the substep of identifying false elements in the complete image timing sample includes the step of determining in the barcode processor the false spaces in the complete image timing sample;

and in which the substep of filtering the false elements from the complete image timing sample includes the substep of filtering in the barcode processor the false spaces from the complete image timing sample.

6. The method of claim 1 in which the substep of identifying false elements in the complete image timing sample includes the step of determining in the barcode processor the false bars in the complete image timing sample;

and in which the substep of filtering the false elements from the complete image timing sample includes the substep of filtering in the barcode processor the false bars from the complete image timing sample.

7. A method for entering information into a processor using a barcode, wherein the barcode includes bars and spaces comprising the elements of the barcode and each bar and space has a width and wherein the barcode contains a pre-printed form composed of a digit code having digit bars and digit spaces, the method comprising the steps of:

modifying a digit bar of the digit code to represent a portion of the information to be entered;

reading the barcode with the modified digit bar using a barcode reader to capture data for forming a complete image timing sample of the barcode;

generating in a barcode processor the complete image timing sample from the data captured by the barcode reader, the complete image timing sample representing the read barcode including the number of elements in the barcode, whether the element is a space or a bar, and the width of each element;

determining in the barcode processor a total number of elements in the complete image timing sample;

comparing in the barcode processor the total number of elements in the complete image timing sample with a desired number of elements for the barcode;

processing the complete image timing sample in the barcode processor to detect the modified digit bar and decode the information contained in the elements of the complete image timing sample if the number of elements in the complete image timing sample equals the desired number; and

processing the complete image timing sample in the barcode processor if the number of elements in the complete image timing sample is greater than the desired number, the processing step including the substeps of

identifying false elements in the complete image timing sample,

filtering the false elements from the complete image timing sample, and

processing the filtered complete image timing sample to detect the modified digit bar and decode the information contained in the elements of the filtered complete image timing sample.

8. The method of claim 7 in which the substep of filtering the false elements from the complete image timing sample, each false element having a width, includes the following steps for each false element:

identifying in the barcode processor the element preceding the false element, the preceding element having a width;

identifying in the barcode processor the element following the false element, the following element having a width;

combining in the barcode processor the width of the false element with the width of the preceding element and the width of the following element, thereby eliminating the false element by transforming it into a portion of the elements preceding and following the false element; and

reducing the total number of elements of the complete image timing sample by two.

9. The method of claim 7 in which the substep of identifying the false elements in the complete image timing sample, each false element having a width, further includes the steps of:

setting a filter threshold in the barcode processor;

comparing in the barcode processor the width of each element in the complete image timing sample representing the digit code of the barcode with the filter threshold; and

identifying in the complete image timing sample as a false element each element having a width less than the filter threshold.

10. The method of claim 9 in which the step of setting the filter threshold includes the steps of:

determining in the barcode processor the total width of all the elements in the digit code; and

dividing the total width by a filter threshold factor.

11. The method of claim 7 in which the substep of identifying the false elements in the complete image timing sample includes the step of determining in the barcode processor the false spaces in the complete image timing sample;

and in which the substep of filtering the false elements from the complete image timing sample includes the substep of filtering in the barcode processor the false spaces from the complete image timing sample.

12. The method of claim 7 in which the substep of identifying the false elements in the complete image timing sample includes the step of determining in the barcode processor the false bars in the complete image timing sample;

and in which the substep of filtering the false elements from the complete image timing sample includes the substep of filtering in the barcode processor the false bars from the complete image timing sample.

13. The method of claim 7 in which the step of modifying a digit bar includes the step of hand-marking the digit bar.

14. The method of claim 7 in which the step of modifying a digit bar includes the step of widening the digit bar into a wider digit bar by marking the digit bar.

15. The method of claim 7 in which the step of detecting the modified digit bar further includes the steps of:

setting a digit bar threshold in the barcode processor;

comparing in the barcode processor the width of each bar in the complete image timing sample representing the digit code of the barcode with the digit bar threshold; and

identifying in the complete image timing sample representing the digit code as a modified digit bar each digit bar having a width greater than the digit bar threshold.

16. The method of claim 15 in which the step of setting the digit bar threshold includes the steps of:

determining in the barcode processor the largest width of the digit bars and the smallest width of the digit bars; and

choosing as the set digit bar threshold a value between the width of the largest and smallest digit bars.

17. The method of claim 16 in which the step of choosing the value of the set digit bar threshold includes the substeps of:

adding the largest and smallest widths of the digit bars; and

dividing the sum of the largest and smallest digit bars by a digit threshold factor.

18. The method of claim 7, in which the barcode includes a start code and a stop code, and the digit code is located between the start and stop codes, further comprising the steps of:

decoding the start code in the barcode processor;

decoding the digit code in the barcode processor;

decoding the stop code in the barcode processor;

comparing in the barcode processor the start code with the stop code; and

producing the decoded information from the digit code if the start code and stop code match.

19. The method of claim 18 in which the step of decoding the digit code further comprises the steps of:

digitizing in the barcode processor a portion of the complete image timing sample representing the digit code of the barcode; and

comparing the digitized portion of the complete image timing sample with a table stored in the barcode processor to identify the information encoded on the barcode.

20. A method for reading an encoded string of characters from a plurality of barcodes arranged in a regular order, each barcode including encoded information representing an encoded character in the string of characters, the method comprising the steps of:

reading with a barcode reader each of the plurality of barcodes;

transmitting the read barcodes to a barcode processor;

extracting encoded position information from each read barcode using the barcode processor, the encoded position information representing a position within the string of characters being decoded of the character encoded in the corresponding barcode;

extracting encoded character information from each read barcode using the barcode processor and decoding a character from the encoded character information; and

generating, using the barcode processor, a decoded string of characters from the extracted position information and decoded characters of the read barcodes.

21. A barcode label for encoding a multi-character string readable by a barcode reader, the label comprising:

a plurality of data lines;

barcode readable start and stop codes unique to each data line; and

a barcode readable digit form located between the start code and the stop code of each data line.

22. The barcode label of claim 21 in which the start code of a data line is identical to the stop code of that data line.

23. The barcode label of claim 21 wherein the digit form includes a plurality of digit bars and digit spaces, each digit space being wider than a digit bar and each digit bar being bounded on each side by a digit space.

24. The barcode label of claim 23 wherein the start, stop, and digit bars are pre-printed indicia on the barcode label.

25. A system for entering into a processor a character marked by hand, the system comprising:

a pre-printed barcode form containing a plurality of bars and spaces representing the elements of a character code, of which at least one of the bars is designed to be modified by hand to represent the character;

barcode reader means for scanning the barcode form with the at least one modified bar and capturing data for forming a complete image timing sample representing the bars, spaces, and at least one modified bar, wherein the complete image timing sample includes the number and width of the bars, spaces, and at least one modified bar; and

means, coupled to the barcode reader means, for generating from data captured by the barcode reader means the complete image timing sample representing the scanned barcode, as modified, and for processing it to distinguish modified bars from unmodified bars and for decoding the modified bars into corresponding characters.

26. The system of claim 25 in which the processing means includes:

means for determining a total number of elements in the complete image timing sample, comparing the total number of elements in the complete image timing sample with a desired number of elements,

detecting any false elements in the complete image timing sample, filtering from the complete image timing sample the false elements, and decoding the elements of the filtered complete image timing sample to obtain the character.

27. The system of claim 26 in which the means for detecting and filtering the false elements includes means for determining false bars in the complete image timing sample and filtering the false bars from the complete image timing sample.

28. The system of claim 26 in which the means for detecting and filtering the false elements includes means for determining false spaces in the complete image timing sample and filtering the false spaces from the complete image timing sample.

29. The system of claim 28 in which the means for detecting and filtering the false spaces in the complete image timing sample further includes means for setting a filter threshold, comparing the width of each space in the complete image timing sample with the filter threshold, and identifying in the complete image timing sample as a false space each space having a width less than the filter threshold.

30. The system of claim 26 in which the means for filtering the false elements from the complete image timing sample further includes means for adding the width of the false element to the width of the element following the false element and the width of the element preceding the false space element and reducing the total number of elements of the complete image timing sample by two for each combination.