Prior art — US Patent 5243655

Analysis of Prior Art for U.S. Patent 5,243,655

To: File
From: Senior Patent Analyst
Date: April 29, 2026
Subject: Prior Art Review for U.S. Patent 5,243,655 ("the '655 patent")

This memorandum outlines the prior art cited during the prosecution of U.S. Patent 5,243,655. Each reference has been reviewed to assess its potential impact on the patent's claims, specifically regarding anticipation under 35 U.S.C. § 102.

The core invention of the '655 patent resides in a system and method for encoding data into a specific two-dimensional stacked bar code symbol (referred to as PDF417) and, more critically, decoding it. The decoding method is robust against skewed scan lines that may cross multiple rows of the symbol. Key features of this decoding method, as recited in the claims, include the use of "row indicator codewords" and distinct "clusters" of codewords to identify the correct row for each decoded symbol character, allowing for the reconstruction of a complete data matrix from partial or angled scans.

Cited U.S. Patent References

1. U.S. Patent 4,794,239 (Allais)

Title: Bar code symbol for representing high density data
Filing Date: September 15, 1987
Publication Date: December 27, 1988
Description: This patent, assigned to Intermec, discloses a "Code 49" stacked symbology. It describes a two-dimensional symbol created by stacking multiple rows of bar codes. Each row includes a start character, data characters, and a stop character. It also teaches the inclusion of a row number and the total number of rows within each row's data, which serves a function similar to the '655 patent's "row indicator codeword."
Potential Anticipation Analysis:
- Claim 1: The Allais patent discloses a system for encoding and decoding a 2D barcode, which includes generating the symbol and reading it with a scanner. This could be argued to anticipate the broad system described in claim 1.
- Claims 16 & 26: Allais teaches identifying rows by a row number encoded within the row itself. However, it does not appear to disclose the specific concept of partitioning codewords into mutually exclusive "clusters" and using that cluster information in combination with a row indicator to determine the correct row for each codeword in a scan line that crosses a row boundary. The '655 patent's method of "stitching" together parts of different rows based on cluster identification appears to be a key distinguishing feature. Therefore, Allais likely does not anticipate the specific decoding process of claims 16 and 26.
- Claim 35: Allais does not explicitly describe a system for generating both machine-readable symbols and human-readable data on a single carrier in a unified process.

2. U.S. Patent 4,874,936 (Chandler et al.)

Title: Two-dimensional bar code and method of reading same
Filing Date: October 21, 1987
Publication Date: October 17, 1989
Description: This patent describes a two-dimensional matrix symbol (which would become known as Code 1). It uses a finder pattern of solid borders and an alternating black/white pattern for determining orientation and location. Data is stored in a grid of cells. The patent discusses a method of reading the symbol with a raster-scanning laser or a CCD camera and assembling the data from the grid.
Potential Anticipation Analysis:
- Claim 1: This patent clearly discloses a system for representing and recognizing data in a 2D graphical form.
- Claims 16 & 26: The decoding method in Chandler et al. relies on locating the finder pattern to establish a coordinate system for the entire matrix. This is fundamentally different from the '655 patent's row-by-row decoding, which uses start/stop patterns, row indicators, and codeword clusters to reassemble data from potentially fragmented scan lines. The '655 patent's approach is designed for hand-held laser scanners that may not capture the entire symbol in one view, whereas Chandler's method seems more suited for image-based readers. The absence of "clusters" and "stitching" of partial scans means it does not anticipate these claims.
- Claim 35: No disclosure of a combined machine-readable and human-readable printing system.

3. U.S. Patent 4,939,354 (Priddy et al.)

Title: System for and method of generating and reading a bar code symbol having a high density of data
Filing Date: April 27, 1989
Publication Date: July 3, 1990
Description: This patent describes a system for encoding data into a "checkerboard" style 2D matrix code. It includes an orientation symbol at one corner and border symbols for defining the symbol's boundaries. The decoding process involves locating these patterns and then reading the grid of data cells.
Potential Anticipation Analysis:
- Claim 1: Discloses a system for encoding and decoding 2D data symbols.
- Claims 16 & 26: Similar to Chandler et al., this patent describes a full-frame matrix symbology. The decoding method is dependent on locating the entire symbol's boundary and orientation markers. It does not teach the concept of stacked rows, row indicators within each row, or codeword clusters to enable the assembly of data from multiple partial scan lines. Therefore, it does not anticipate the specific decoding method of claims 16 and 26.
- Claim 35: No disclosure of a combined machine-readable and human-readable printing system.

4. U.S. Patent 5,128,525 (Stearns et al.)

Title: System for decoding bar code symbols employing a list of candidate characters
Filing Date: November 1, 1990
Publication Date: July 7, 1992
Description: This patent focuses on a decoding algorithm that, when an exact match for a scanned bar/space pattern is not found, generates a list of "candidate characters" that are close matches. This improves decoding robustness for poorly printed or damaged symbols.
Potential Anticipation Analysis:
- Claim 1: Discloses a "recognition means" but not the complete encoding and printing system.
- Claims 16 & 26: This reference details a character-level decoding technique, not the symbol-level architecture described in the '655 claims. It does not teach the use of row indicators, clusters, or the assembly of a codeword matrix from partial scans. It could be seen as a potential component of a decoder, but it does not anticipate the overall decoding process of the '655 patent.
- Claim 35: Not relevant.

Cited Foreign Patent References

1. European Patent Application EP 0353483 A2 (Itab-Scan-Tronic AB)

Title: A method and a device for reading a code pattern
Filing Date: July 26, 1989
Publication Date: February 7, 1990
Description: This application describes a method for reading a 2D code composed of a matrix of dots. The method involves using an image sensor (like a CCD) to capture the entire symbol, locating reference markings to determine orientation and scale, and then reading the data dots relative to these markings.
Potential Anticipation Analysis:
- Claims 1, 16, 26: This system, like those of Chandler and Priddy, is based on a full-frame imaging approach rather than a line-by-line scanning and reconstruction method. It does not disclose the stacked-row structure, row-specific indicators, or the concept of codeword "clusters" as taught in the '655 patent. Therefore, it does not anticipate the key decoding claims.
- Claim 35: Not relevant.

Conclusion

The prior art cited against the '655 patent, particularly U.S. Patent 4,794,239 (Allais), discloses the general concept of stacked two-dimensional bar codes with row-identifying information. However, none of the cited references appear to explicitly or inherently disclose the '655 patent's specific and novel combination of features for decoding such a symbol. The critical distinguishing element is the use of mutually exclusive codeword clusters that change predictably from row to row, which, when used in conjunction with row indicator codewords, allows the decoder to "stitch" together codeword data from a single, skewed scan line that crosses multiple rows into their correct positions in a final data matrix. This specific methodology for achieving robust decoding with a hand-held scanner is what differentiates the '655 invention from the cited art, thereby preventing anticipation under 35 U.S.C. § 102.