Orientational disambiguation for self-clocking glyph codes

• US 6,182,901 B1
• Filed: 09/21/1995
• Issued: 02/06/2001
• Est. Priority Date: 12/22/1993
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Flores, L. Noah, Hecht, David L.
• Primary Examiner(s): Frech, Karl D.
• Application Number:
  US08/532,040
• Time in Patent Office: 1,965 Days
• Field of Search: 235/494, 235/487
• US Class Current: 235/494
• CPC Class Codes: G06K 19/06037 multi-dimensional coding
• CPC Class Codes: G06K 7/14 using light without selection of wavelength, e.g. sensing reflected white light G06K7/10831 - G06K7/1097 take precedence
• CPC Class Codes: G06K 7/143 Glyph-codes

Abstract

An optically readable record for storing encoded information comprises (1) a recording medium, (2) a self-clocking data code for encoding the information, with this data code being composed of glyphs that are written in a two dimensional code field on the recording medium on centers that are spatially distributed in nominal accordance with a predetermined spatial formatting rule. The glyphs are defined by respective symbols that are selected from a finite set of optically discriminable symbols to encode the information. Further, there is at least one additional glyph pattern that is written on the recording medium in nominal accordance with the aforementioned spatial formatting rule, with this additional code pattern being discriminable from the data code and being selected to disambiguate data codes that are rotated and/or reflected.

Claims

1. An optically readable record for storing encoded digital information;

said record comprising

a recording medium;

a self-clocking data code pattern for encoding said information;

said data code pattern being composed of glyphs that are written in a two dimensional code field on said recording medium on centers that are spatially distributed in nominal accordance with a predetermined spatial formatting rule;

said glyphs being defined by respective symbols that are selected from a finite set of optically discriminable symbols to encode said digital information; and

at least one additional code pattern that is written on linearly aligned centers on said recording medium in nominal accordance with said spatial formatting rule, said additional code pattern being composed of glyphs which are selected from said finite set of symbols in accordance with a predetermined, asymmetric digital code sequence, whereby said asymmetric code sequence disambiguates between data codes that are rotated 0° and

180°

, even though said data code pattern and said additional code pattern are composed of glyphs that provide a substantially uniform visual appearance.

2. The record of claim 1 wherein

said additional code pattern is further selected to also disambiguate data codes that are rotated 90° and 270°

.

3. The record of claim 2 wherein

said additional code pattern os further selected to also disambiguate mirror image transformed data code patterns.

4. The record of any of claims 1-3 wherein

said glyphs are composed of elongated slash-like symbols that oriented at different angles to encode different digital values.

5. The record of claim 4 wherein

said glyphs are oriented at +45°

and −

45°

with respect to a vertical axis of said recording medium for encoding different binary values.