US5537431A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for bar code reading and decoding
Assignee: International Business Machines Corp
•
Filing: 1994-06-15
•
Granted: 1996-07-16
•
Expires: 2014-06-15
Abstract
Abstract A method and apparatus reliably and robustly decode single width bar codes that may be placed on a variety of materials. The decoding is independent of whether or not the bar code represents dark bars on a light background or light bars on a dark background. The decoder may be implemented either in hardware or as part of a program in a stored program general purpose computer. The signal processing approach taken generates gap sequence information from width sequence information to match predetermined gap sequence patterns. The method and apparatus of the present invention are also particularly amenable to independent creation of the gap sequences from three different techniques which are independent and which thus add robustness to the system. Lastly, the decoding method of the present invention takes advantage of a preprocessing function to remove any certain forms of noise that may be present in the scanned data.
Inventors
- 👤 Chin-Long Chen
- 👤 Mu-Yue Hsiao
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 06:52
CPC Classifications
G; G06; G06K; G06K7/00; G06K7/10; G06K7/14; G06K7/1404; G06K7/146; G06K7/1486; Y; Y10; Y10S; Y10S235/00; Y10S235/901
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
111 words
A method for decoding a bar code pattern, said method comprising the steps of: scanning said bar code pattern to produce an electrical output waveform representation of reflective variations occurring during said scanning; converting said electrical output waveform to a sequence of binary signals representative of bar and space widths in said bar code pattern so as to produce a width signal sequence representing, in alternating fashion, the bar and space widths present in said bar code pattern; converting said width signal sequence to a gap signal sequence; and comparing portions of said gap signal sequence with predetermined gap sequence patterns to determine a symbol represented by said bar code pattern.
Claim 2
Independent Claim
111 words
A method for decoding a bar code pattern, said method comprising the steps of: scanning said bar code pattern to produce an electrical output waveform representation of reflective variations occurring during said scanning; converting said electrical output waveform to a sequence of binary signals representative of bar and space widths in said bar code pattern so as to produce a width signal sequence representing, in alternating fashion, the bar and space widths present in said bar code pattern; converting said width signal sequence to a gap signal sequence; and comparing portions of said gap signal sequence with predetermined gap sequence patterns to determine a symbol represented by said bar code pattern.
Claim 3
Dependent Claim
37 words
The method of claim 1 further including the step of adjusting said width signal sequence to remove extraneous signal spikes or signal dropouts, said adjusting being performed just after said step of converting said electrical output waveform.
Claim 4
Dependent Claim
58 words
The method of claim 1 further including the step of determining from said bar and space widths and from bar and space positions, as specified by said width signal sequence, beginning and end positions of the bar code pattern so as to eliminate from said width signal sequence all signal portions lying outside said beginning and end positions.
Claim 5
Dependent Claim
60 words
The method of claim 1 in which said gap signal converting is based on at least one of the following steps: a.) determining said gap signal sequence based on center-to-center width sequence values; b.) determining said gap signal sequence based on leading edge-to-leading edge sequence values; and c.) determining said gap signal sequence based on trailing edge-to-trailing edge sequence values.
Claim 6
Independent Claim
40 words
A method for decoding a bar code pattern having a check sum symbol, said method comprising the steps of: a.) 1. scanning said bar code pattern to produce an electrical output waveform representative of reflective variations occurring during said scanning;
Claim 7
Independent Claim
40 words
A method for decoding a bar code pattern having a check sum symbol, said method comprising the steps of: a.) 1. scanning said bar code pattern to produce an electrical output waveform representative of reflective variations occurring during said scanning;
Claim 8
Dependent Claim
121 words
converting said electrical output waveform to a sequence of binary signals representative of bar and space widths in said bar code pattern so as to produce a width signal sequence representing, in an alternating fashion, bar and space widths present in said bar code pattern; 3. converting said width signal sequence to a gap signal sequence; 4. comparing said gap signal sequence with predetermined gap sequence patterns to produce a symbol sequence including said check sum symbol; b.) determining if said check sum symbol is correct and repeating steps a.) 1 through a.) 4 for a specified number of times if said check sum symbol is incorrect; and c.) indicating a decoded symbol pattern or that an uncorrectable error has occurred.
Claim 9
Dependent Claim
121 words
converting said electrical output waveform to a sequence of binary signals representative of bar and space widths in said bar code pattern so as to produce a width signal sequence representing, in an alternating fashion, bar and space widths present in said bar code pattern; 3. converting said width signal sequence to a gap signal sequence; 4. comparing said gap signal sequence with predetermined gap sequence patterns to produce a symbol sequence including said check sum symbol; b.) determining if said check sum symbol is correct and repeating steps a.) 1 through a.) 4 for a specified number of times if said check sum symbol is incorrect; and c.) indicating a decoded symbol pattern or that an uncorrectable error has occurred.
Claim 10
Independent Claim
35 words
A method for decoding a bar code pattern, said method comprising the steps of: a.) 1. scanning said bar code pattern to produce an electrical output waveform representative of reflective variations occurring during said scanning;
Claim 11
Independent Claim
35 words
A method for decoding a bar code pattern, said method comprising the steps of: a.) 1. scanning said bar code pattern to produce an electrical output waveform representative of reflective variations occurring during said scanning;
Claim 12
Dependent Claim
114 words
converting said electrical output waveform to a sequence of binary signals representative of bar and space widths in said bar code pattern so as to produce a width signal sequence representing, in an alternating fashion, bar and space widths present in said bar code pattern; 3. converting said width signal sequence to a gap signal sequence; and 4. comparing said gap signal sequence with predetermined gap sequence patterns to produce a symbol sequence; b.) repeating steps a.) 1 through a.) 2 for a specified number of times; and c.) indicating a decoded symbol pattern or that an uncorrectable error has occurred based on the results from said repeated steps a.) 1 through a.) 4.
Claim 13
Dependent Claim
114 words
converting said electrical output waveform to a sequence of binary signals representative of bar and space widths in said bar code pattern so as to produce a width signal sequence representing, in an alternating fashion, bar and space widths present in said bar code pattern; 3. converting said width signal sequence to a gap signal sequence; and 4. comparing said gap signal sequence with predetermined gap sequence patterns to produce a symbol sequence; b.) repeating steps a.) 1 through a.) 2 for a specified number of times; and c.) indicating a decoded symbol pattern or that an uncorrectable error has occurred based on the results from said repeated steps a.) 1 through a.) 4.
Claim 14
Dependent Claim
24 words
The method of claim 6 in which the indicated decoded symbol pattern is that pattern that is detected in a majority of said repetitions.
Claim 15
Independent Claim
35 words
A method for decoding a bar code pattern, said method comprising the steps of: a.) 1. scanning said bar code pattern to produce an electrical output waveform representative of reflective variations occurring during said scanning;
Claim 16
Independent Claim
35 words
A method for decoding a bar code pattern, said method comprising the steps of: a.) 1. scanning said bar code pattern to produce an electrical output waveform representative of reflective variations occurring during said scanning;
Claim 17
Dependent Claim
142 words
converting said electrical output waveform to a sequence of binary signals representative of bar and space widths in said bar code pattern so as to produce a width signal sequence representing, in alternating fashion, the bar and space widths present in said bar code pattern; 3. converting said width signal sequence to produce a gap signal sequence based upon values selected from the group consisting of center-to-center width sequence values, leading edge-to-leading edge sequence and trailing edge-to-trailing edge sequence values; and 4. comparing said gap signal sequence with predetermined gap sequence patterns to produce a symbol sequence; and b.) repeating the steps a.) 1 through a.) 4 for a specified number of times to produce a plurality of gap signal sequences; and c.) indicating a decoded symbol pattern or that an uncorrectable error has occurred based on the results from said repetition.
Claim 18
Dependent Claim
142 words
converting said electrical output waveform to a sequence of binary signals representative of bar and space widths in said bar code pattern so as to produce a width signal sequence representing, in alternating fashion, the bar and space widths present in said bar code pattern; 3. converting said width signal sequence to produce a gap signal sequence based upon values selected from the group consisting of center-to-center width sequence values, leading edge-to-leading edge sequence and trailing edge-to-trailing edge sequence values; and 4. comparing said gap signal sequence with predetermined gap sequence patterns to produce a symbol sequence; and b.) repeating the steps a.) 1 through a.) 4 for a specified number of times to produce a plurality of gap signal sequences; and c.) indicating a decoded symbol pattern or that an uncorrectable error has occurred based on the results from said repetition.
Claim 19
Dependent Claim
24 words
The method of claim 8 in which the indicated decoded symbol pattern is that pattern that is detected in a majority of said repetitions.
References Cited (Backward Citations)
US4656345A
Cited
US4757206A
Cited
US4687912A
Cited
US4777357A
Cited
US4833306A
Cited
US5070504A
Cited
US5268566A
Cited
US5420411A
Cited
US5324924A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-07-16 | 2000-01-15 | 2000-07-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-07-16 | 2004-01-15 | 2004-07-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-07-16 | 2008-01-15 | 2008-07-16 | $7700.00 | Window Closed / Lapsed |