High density two-dimensional bar code symbol
US5304786A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 5, 1990 |
| Grant date | Apr 19, 1994 |
| Priority date | — |
| Expiry date | Jan 5, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2201/3278
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A nonvolatile electro-optical read-only memory includes a substrate on which is printed (or otherwise inscribed) a complex symbol or "label" with a high density two-dimensional symbology, a variable number of component symbols or "codewords" per row, and a variable number of rows. Codewords in alternating rows are selected from mutually exclusive subsets of a mark pattern such as a (17,4) mark pattern. The subsets are defined in terms of particular values of a discriminator function, which is illustrated as being a function of the widths of bars and spaces in a given codeword. In the illustrated embodiment, each subset includes 929 available codewords; that, plus a two-step method of decoding scanned data, permitting significant flexibility in defining mappings of human-readable symbol sets into codewords. The memory may be used in conjunction with a scanner and a suitable control system in a number of applications, e.g., robotic operations or automated microfilm searching.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.