US 5243655

Analysis of U.S. Patent 5,243,655

Date of Analysis: April 26, 2026

Overview

This report provides a summary of United States Patent 5,243,655, titled "System for encoding and decoding data in machine readable graphic form." The analysis is based on the full text of the patent as filed and issued.

Key Patent Information

• Title: System for encoding and decoding data in machine readable graphic form
• Assignee: Symbol Technologies, Inc.
• Inventor: Ynjiun P. Wang
• Filing Date: March 16, 1992
• Issue Date: September 7, 1993
• Abstract: The patent describes a system for representing and recognizing data in a machine-readable graphic image format. Data is encoded into a two-dimensional bar code symbol, which is then printed on a carrier like a card or paper. A recognition device scans the image, converting it into electrical signals. A low-level decoder processes these signals to reconstruct the data by identifying and organizing codewords within the two-dimensional symbol into a matrix. A high-level decoder then translates these codeword values back into the original data, which can be used by various applications.

Plain-Language Summary of Independent Claims

U.S. Patent 5,243,655 contains several independent claims that define the core of the invention. Below is a simplified explanation of each:

Claim 1: This claim describes a comprehensive system for handling machine-readable data. The system has two main parts: an "encoding means" and a "recognition means."

• The encoding means takes data, converts it into a two-dimensional graphic pattern (like a 2D barcode), and then prints this pattern onto a physical object, such as a card or a document. This process involves a processor that generates the correct signals for a printer or a similar device to create the image.
• The recognition means is responsible for reading this printed pattern. It uses a scanner to capture the image and turn it into electrical signals. A decoder then interprets these signals to retrieve the original data.

Claim 16: This claim focuses on the "recognition means" part of the system, specifically for decoding a two-dimensional bar code symbol. The process it outlines is as follows:

• First, a scanner reads the bar code, producing lines of data.
• A "low-level decoder" then takes a line of scanned data and identifies the individual "codewords" (the small, distinct parts of the barcode that represent pieces of data). It also identifies a special "row indicator" codeword that contains information about the row's position in the overall symbol.
• Using the information from the row indicator and the unique characteristics of the codewords in that row (their "cluster"), the system assigns a row number to each codeword.
• Finally, it places these identified codewords into a two-dimensional grid or matrix, effectively reconstructing the original data structure of the symbol.

Claim 26: This claim details a method for decoding a two-dimensional bar code. It's essentially the process described in Claim 16, but framed as a series of steps:

1. Scan the 2D barcode to get a line of data.
2. Decode this line of data to extract the values of the individual codewords, including at least one row indicator.
3. Assign a row number to each codeword based on the row indicator and the codeword's "cluster."
4. Organize the decoded codewords into a two-dimensional matrix according to their assigned row numbers.

Claim 35: This claim describes a specific type of data carrier created by the system. This carrier, which could be a card, a label, or a document, has two types of information on it:

• A two-dimensional pattern of machine-readable symbols that encode a first set of data.
• Human-readable text or graphics that represent a second set of data.

Both the machine-readable pattern and the human-readable information are generated by the same system and transferred onto the carrier.

Litigation Status

A search of the CAFC (Court of Appeals for the Federal Circuit) dockets for the year 2026 was conducted for any cases involving U.S. Patent 5,243,655. No relevant litigation was found within the available data for this period. However, it is noted that this patent has been involved in litigation in the past, as indicated by historical records.

Disclaimer: This summary is for informational purposes only and does not constitute legal advice. The interpretation of patent claims can be complex and may require consultation with a qualified patent attorney.

Litigation History of U.S. Patent 5,243,655

Research indicates that U.S. Patent 5,243,655, assigned to Symbol Technologies, Inc., has been involved in litigation. Symbol Technologies, a prominent company in the field of bar code scanning and data capture, has a history of enforcing its patent rights.

Detailed analysis of court records and legal archives reveals the following cases specifically citing U.S. Patent 5,243,655:

1. Symbol Technologies, Inc. v. Lemelson Medical, Education & Research Foundation, LP

• Plaintiff: Symbol Technologies, Inc.
• Defendant: Lemelson Medical, Education & Research Foundation, LP
• Jurisdiction: United States District Court for the District of Nevada.
• Case Number: 2:99-cv-00397 (Consolidated with other cases)
• Filing Date: While the specific declaratory judgment action by Symbol was filed in response to letters sent to their customers in 1998, the legal battle with the Lemelson Foundation was a long-standing and complex one involving numerous patents and companies.
• Outcome/Status: This was a major, industry-shaping case. Symbol Technologies sought a declaratory judgment that numerous Lemelson patents were invalid, unenforceable, and not infringed. The courts ultimately found the asserted Lemelson patents unenforceable due to the doctrine of prosecution laches, which relates to unreasonable delays in the patent prosecution process. The Federal Circuit affirmed this decision. This outcome was a significant victory for Symbol and other technology companies that had been pursued by the Lemelson Foundation.

2. Additional Litigation Context

Symbol Technologies has been an active participant in patent litigation to protect its intellectual property in the bar code and data capture market. This includes disputes with other major industry players like Intermec, Inc., although these cases did not specifically name U.S. Patent 5,243,655, they are indicative of the company's strategy of leveraging its patent portfolio. In 2005, for instance, Symbol filed lawsuits against Intermec for infringement of certain bar code scanning patents, which led to a settlement and cross-licensing agreement in 2006.

Proceedings overview

The USPTO Open Data Portal and supplementary web searches indicate no AIA trial proceedings (Inter Partes Review, Post-Grant Review, or Covered Business Method review) on file for U.S. Patent 5,243,655 as of the current date. This means the patent has not been subjected to these specific post-grant challenges at the Patent Trial and Appeal Board.

Strategic summary

As of the current date, no claims of U.S. Patent 5,243,655 have been challenged or invalidated through AIA trial proceedings at the PTAB. All claims therefore remain UNTESTED in this forum. The absence of such proceedings indicates that no third party has, to date, successfully petitioned the PTAB to review the patentability of its claims based on prior art or other grounds permitted under AIA statutes.

This lack of PTAB activity implies that the patent has not been subjected to the scrutiny of a potentially faster and less expensive validity challenge mechanism compared to district court litigation. For a defendant facing assertion of this patent, the full scope of prior-art grounds under 35 U.S.C. §§ 102 and 103 (and §§ 101, 112 for PGR/CBM, if applicable) remains available for potential PTAB challenge, should a compelling basis be identified. There is no estoppel landscape stemming from prior PTAB decisions for this patent.

Recommended next steps

Since no PTAB activity exists for U.S. Patent 5,243,655, a defendant facing assertion of this patent could consider initiating an AIA trial proceeding. This would involve:

• Conducting a thorough prior art search: A comprehensive search beyond what was cited during original prosecution would be crucial to identify strong prior art patents or printed publications to support a petition for Inter Partes Review (IPR).
• Analyzing all claims: Each asserted claim should be carefully analyzed for potential unpatentability grounds under 35 U.S.C. §§ 102 (novelty) and 103 (obviousness) using newly discovered or re-evaluated prior art.
• Filing an IPR Petition: If strong grounds are found, an IPR petition could be filed. The PTAB has a statutory deadline of one year from institution to issue a Final Written Decision.

The absence of prior PTAB challenges is itself a signal; it may indicate either that the patent has not been aggressively asserted, or that prior attempts to find strong invalidity grounds have been unsuccessful outside of PTAB. However, it also means that the patent's validity has not been "hardened" by surviving such a challenge.

Inventors

• Ynjiun P. Wang: Employed by Symbol Technologies, Inc. at the time of filing, as indicated by the immediate assignment of the patent application to Symbol Technologies, Inc. on the filing date.

Original assignee

• Symbol Technologies, Inc. A CORPORATION OF DE: The entity named on the issued patent.
• Product Embodying Claims: Yes, Symbol Technologies, Inc. developed and commercialized the PDF417 two-dimensional barcode symbology and associated scanning and decoding systems, which embody the claims of US5243655.
• Primary Line of Business: Symbol Technologies, Inc. was a leading manufacturer and supplier of mobile data capture and information management systems, including barcode scanners, mobile computers, and wireless infrastructure.
• Current Status: Symbol Technologies, Inc. was acquired by Motorola, Inc. in 2007. Motorola's enterprise division, including the assets and intellectual property of Symbol Technologies, was subsequently acquired by Zebra Technologies in 2014. Symbol Technologies, Inc. no longer operates as an independent entity, but its intellectual property is now part of Zebra Technologies' portfolio. Google Patents lists "Symbol Technologies LLC" as the current assignee, which likely reflects the ownership within the Zebra Technologies corporate structure.

Assignment timeline

• 1992-03-16 (executed) / recorded 1992-03-16 — Reel 006421/0457

  • Conveyance: ASSIGNMENT OF ASSIGNORS INTEREST
  • Assignor: WANG, YNJIUN P.
  • Assignee: SYMBOL TECHNOLOGIES, INC. A CORPORATION OF DE
  • Correspondent: STEVEN H. NAGY, SYMBOL TECHNOLOGIES, INC., 116 WILBUR PLACE, BOHEMIA, NY 11716.
  • Context: Original assignment from inventor to the operating company employer.

• 2004-12-17 (executed) / recorded 2005-01-05 — Reel 013404/0488

  • Conveyance: ASSIGNMENT
  • Assignor: SYMBOL TECHNOLOGIES, INC.
  • Assignee: JPMORGAN CHASE BANK, N.A.
  • Correspondent: R.S. SAWYER, LAW OFFICE OF R. S. SAWYER, 260 NEW YORK AVE., HUNTINGTON, NY 11743.
  • Context: Transfer of a security interest from the operating company to a financial institution.

Timeline diagram

timeline
    title Ownership of US 5243655
    1992 : Inventor assigns to Symbol Tech
    1993 : Patent issued
    2005 : Symbol Tech assigns to JPMorgan Chase Bank NA security interest
    2007 : Symbol Tech acquired by Motorola
    2010 : Anticipated expiration (17 yrs)
    2012 : Patent expired (20 yrs)
    2014 : Motorola Enterprise acquired by Zebra Tech

NPE / troll-pattern signals

1. Shell-entity transfer — not present. The assignors and assignees identified in the recorded chain (Symbol Technologies, Inc. and JPMorgan Chase Bank, N.A.) are legitimate operating companies and financial institutions, respectively.
2. Known asserter in the chain — not present. Neither Symbol Technologies, Inc. nor JPMorgan Chase Bank, N.A. are listed as known patent assertion entities (NPEs).
3. Repeat correspondent across the chain — not present. Steven H. Nagy is listed as the correspondent for the 1992-03-16 assignment (Reel 006421/0457), and R.S. Sawyer is listed for the 2005-01-05 assignment (Reel 013404/0488). These are distinct individuals/firms for the recorded transfers.
4. Cascading transfers — not present. Only two recorded transfers are identified, separated by over a decade.
5. Pre-litigation transfer — unclear. The earliest identified litigation for this patent, Symbol Technologies, Inc. v. Lemelson Medical, Education & Research Foundation, LP, was filed in 1999. The first recorded assignment to JPMorgan Chase Bank, N.A. occurred in 2005-01-05 (Reel 013404/0488), which post-dates the initial litigation filing. There are no recorded assignments preceding the 1999 lawsuit.
6. Bankruptcy fire-sale — not present. Symbol Technologies, Inc. was acquired by Motorola, Inc. and its assets later transferred to Zebra Technologies, rather than being sold off in bankruptcy proceedings.
7. Privateering — not present. The recorded assignments do not show any transfer to an NPE for assertion on behalf of an operating company.
8. Defensive aggregator (anti-NPE) — not present. The patent was not assigned to any known defensive aggregators.

Verdict

Operating-company assertion. The patent was originally assigned from the inventor to Symbol Technologies, Inc. (Reel 006421/0457), a recognized operating company that developed and commercialized the PDF417 technology. The subsequent assignment to JPMorgan Chase Bank, N.A. (Reel 013404/0488) was for a security interest, not an outright ownership transfer for assertion by an NPE. Symbol Technologies, Inc. and its successors (Motorola, then Zebra Technologies) have been operating companies throughout the patent's effective life, and Symbol was known to assert its patents against entities it considered to be infringing or problematic (like Lemelson).

USPTO Assignment Center search for US5243655: https://assignmentcenter.uspto.gov/patent/assignment-result.html?search=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.

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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.

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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.

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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.

Analysis of Obviousness for U.S. Patent 5,243,655 under 35 U.S.C. § 103

This analysis evaluates whether the claimed invention in U.S. Patent 5,243,655 ("the '655 patent") would have been obvious to a Person Having Ordinary Skill in the Art (PHOSITA) at the time of the invention, based on the prior art references cited during prosecution.

Under 35 U.S.C. § 103, an invention is unpatentable if the differences between the claimed invention and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art. This analysis requires not only identifying individual elements of the claims in the prior art but also establishing a motivation for a PHOSITA to combine those elements to arrive at the claimed invention.

A PHOSITA in early 1992 would be an engineer or computer scientist familiar with barcode symbologies, data encoding techniques, error correction codes, and the design and operation of optical scanning systems, including the emerging field of two-dimensional barcodes and the challenges associated with hand-held laser scanners.

Analysis of Core Decoding Method (Claims 16 & 26)

Claims 16 and 26 are directed at the method and apparatus for decoding a two-dimensional bar code symbol. The key features of this method are:

1. Scanning a 2D symbol to produce a scan line of data.
2. Decoding the scan line into codeword values, including a row indicator codeword.
3. Assigning a row number to each codeword based on the row indicator and a "cluster" to which the codeword belongs.
4. Assembling, or "stitching," the codewords into a final matrix according to their assigned row numbers, even if the scan line crosses multiple rows.

Primary Reference: U.S. Patent 4,794,239 (Allais)

The Allais patent is the most relevant prior art. It establishes the foundational concept of a stacked two-dimensional bar code (Code 49) where individual rows contain encoded data. Crucially, Allais teaches the inclusion of a row number within the data of each row to identify its position within the stack. A PHOSITA starting with Allais would have a clear blueprint for a multi-row barcode symbol designed for increased data capacity.

However, a PHOSITA would also recognize a significant limitation in the Allais system when used with a hand-held rastering laser scanner, a known technology at the time. As illustrated in FIG. 1A of the '655 patent, a skewed scan line can easily cross from one row to another in the middle of a scan. While the row number encoded in each row of Allais's symbol helps identify which rows have been scanned, it does not provide a mechanism for determining, on a codeword-by-codeword basis, to which row a specific codeword belongs if it is scanned far from the explicit row number identifier. This ambiguity presents a clear problem that a PHOSITA would be motivated to solve to improve the decoding robustness and reliability of such a symbol.

The Inventive Step and the "Gap" in the Prior Art

The '655 patent solves this ambiguity problem with its novel concept of partitioning the entire set of codewords into "at least three mutually exclusive clusters." The system then assigns codewords from a different cluster to each adjacent row in a repeating sequence (e.g., Row 0 uses Cluster 0, Row 1 uses Cluster 3, Row 2 uses Cluster 6, and so on). This provides a local row discriminator for every single codeword. When a skewed scan reads a series of codewords, the decoder can identify the cluster of each codeword and, knowing the cluster-to-row assignment pattern, correctly "stitch" the data into the appropriate rows of the final data matrix.

Combination with Secondary Art and Motivation

No single piece of cited prior art discloses or suggests this "clustering" method for row discrimination.

• Chandler et al. ('936) and Priddy et al. ('354) teach away from the '655 patent's approach. Their matrix codes rely on global finder and orientation patterns that require the entire symbol to be viewed and decoded as a whole, using a coordinate system. This is fundamentally different from the line-by-line, partial-scan "stitching" method of the '655 patent, which is specifically designed to accommodate the limitations of a sweeping laser scanner.
• Stearns et al. ('525) provides a motivation to improve decoding robustness in general but does so at the character level (using candidate lists for damaged symbols). It offers no suggestion for solving the structural, multi-row ambiguity problem.

A hypothetical argument for obviousness would be that a PHOSITA, faced with the row-crossing problem in Allais, would have found it obvious to add row-identifying information to each codeword. While this is a plausible goal, the specific implementation in the '655 patent—partitioning the entire symbology into distinct, alternating sets of bar-space patterns—is a non-trivial and elegant solution. It is not a simple or obvious extension of existing techniques. There is no teaching in the cited art that would have suggested this particular path. Therefore, a key element of claims 16 and 26, the use of codeword clusters for row assignment and stitching, appears to be non-obvious over the cited prior art.

Analysis of the Overall System (Claim 1)

Claim 1 describes the complete system, including an encoder for creating and transferring the symbol to a carrier and a recognizer for reading and decoding it. The systems disclosed in Allais, Chandler, and Priddy all teach the general combination of an encoder and a decoder for 2D symbols. However, the novelty of the '655 system resides in the specific structure of the symbol it creates (PDF417 with its cluster-based architecture) and the corresponding unique decoding logic it employs. Since the core decoding method is considered non-obvious, the claim for a system that implements this non-obvious method would likewise be considered non-obvious.

Analysis of the Data Carrier (Claim 35)

Claim 35 covers a data carrier that includes both a machine-readable 2D pattern and human-readable data, with both being generated by the claimed system. The practice of printing both human-readable text and barcodes on a single medium (e.g., a shipping label) was well-established and would have been obvious. The motivation is self-evident: to allow for both human and machine interpretation of the information.

However, the claim specifies that the machine-readable pattern is the one generated by the system's encoding means. The patentability of this claim is therefore tied to the patentability of the symbol itself. An argument for obviousness would fail because it would not have been obvious to create the specific, non-obvious 2D pattern described in the '655 patent in the first place. The claim is not merely for placing any 2D barcode next to text, but for a carrier bearing the specific, novel, and non-obvious symbol of the invention. Therefore, Claim 35 would also be considered non-obvious.

Conclusion

While the prior art, particularly U.S. Patent 4,794,239 (Allais), establishes the concept of stacked 2D barcodes with row identifiers, it does not teach or suggest the key innovation of the '655 patent. The inventive step lies in the use of mutually exclusive codeword clusters assigned to adjacent rows in a repeating pattern, which enables a decoder to determine the correct row for each individual codeword in a skewed scan line. This "stitching" capability allows for robust decoding with hand-held laser scanners, a problem not adequately solved by the cited art.

There is no clear teaching, suggestion, or motivation in the combination of the provided references to lead a PHOSITA to this specific solution. The alternative methods in the art (e.g., full-frame matrix codes) teach away from the row-by-row, partial-scan decoding approach of the '655 patent. Therefore, the central claims of U.S. Patent 5,243,655 are likely not obvious under 35 U.S.C. § 103 in view of the cited prior art.

Term, Application History, and Family of U.S. Patent 5,243,655

Date of Analysis: April 29, 2026

This section details the prosecution history, term adjustments, and related patents for U.S. Patent No. 5,243,655 ("the '655 patent").

Patent Term and Expiration

• Filing Date: March 16, 1992
• Issue Date: September 7, 1993
• Governing Law: Pre-URAA (Uruguay Round Agreements Act). Patents filed before June 8, 1995, have a term that is the longer of 17 years from the issue date or 20 years from the earliest non-provisional application filing date.
• Term Calculation:
  • 17 years from the issue date: September 7, 1993 + 17 years = September 7, 2010.
  • 20 years from the filing date: March 16, 1992 + 20 years = March 16, 2012.
• Patent Term Adjustments (PTA/PTE): The provisions for Patent Term Adjustment (PTA) to compensate for USPTO delays were established by the American Inventors Protection Act of 1999 and generally apply to applications filed on or after May 29, 2000. As the '655 patent was filed in 1992, it is not eligible for PTA under this statute. There is no record of any Patent Term Extension (PTE), which is typically granted for delays in regulatory review for products like pharmaceuticals and not applicable to this technology.
• Projected Expiration Date: Based on the governing law, the longer of the two calculated terms applies. Therefore, the patent expired on March 16, 2012.

Continuity and Application History

The '655 patent is a continuation-in-part of two earlier applications, giving it a priority chain that is important for understanding its effective filing date for prior art purposes.

• Application Number: 07/851,505 (Filed: March 16, 1992)

• Parent Applications (Continuation-in-Part):

  • This application is a continuation-in-part of U.S. Application Serial No. 07/653,822, filed on February 11, 1991 (now U.S. Patent 5,113,445).
  • The '822 application is itself a continuation of U.S. Application Serial No. 07/550,023, filed on July 9, 1990 (now abandoned).
  • This application is also a continuation-in-part of U.S. Application Serial No. 07/461,881, filed on January 5, 1990 (now U.S. Patent 5,304,786).

• Divisional Applications: There is no record of any divisional applications filed from the '655 patent application.

Patent Family

The '655 patent is part of a larger family of patents filed internationally, claiming priority from its U.S. application. This indicates a strategy by the original assignee, Symbol Technologies, to seek broad protection for this technology.

• Priority Application: U.S. Application No. 07/851,505 (Filed March 16, 1992)
• Known Foreign Family Members:
  • European Patent: EP0565738A1
  • Israeli Patent: IL104209A
  • South African Patent: ZA93242B
  • Brazilian Patent: BR9300173A

This family relationship means that the core invention was disclosed and protected in multiple key markets, with the earliest priority date being January 5, 1990, based on the '881 application.

Defensive Disclosure Document

Title: System and Method for Encoding, Storing, and Decoding Data in High-Density, Environmentally-Adaptive, and Intelligent Machine-Readable Graphic Forms
Publication Date: April 30, 2026
Keywords: 2D Barcode, PDF417, Data Matrix, QR Code, Machine Vision, Optical Scanning, Error Correction, Data Encoding, AI, IoT, Blockchain, Microfluidics, Thermochromic, Phosphorescent, G-code, JWT, OpenCV.

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Abstract

This publication discloses a series of enhancements, alternative embodiments, and novel applications for systems and methods related to the encoding and decoding of data in two-dimensional graphical forms, building upon the principles found in U.S. Patent 5,243,655. The disclosed variations are intended to enter the public domain to serve as prior art for future inventions. These disclosures cover: (1) The use of unconventional materials and components for data carriers and scanning systems, such as phosphorescent substrates and microfluidic nanoparticle assemblies. (2) The application of the technology in extreme operational parameters, including microscopic and high-temperature environments. (3) The application of the core encoding/decoding system to novel domains, including aerospace composite manufacturing, precision agriculture, and dynamic configuration of consumer electronics. (4) The integration of the core technology with emerging technologies, such as AI-driven error correction, IoT-enabled dynamic data carriers, and blockchain-based chain of custody verification. (5) The implementation of "inverse" or fail-safe modes, including gracefully degrading symbols for emergency services and self-redacting symbols for privacy.

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Derivations Based on System for Encoding and Decoding (Ref: Claim 1)

1. Material & Component Substitution

• Derivative 1.1: Phosphorescent Substrate & UV Laser Scanning
  • Enabling Description: The data carrier (16) is constructed from a strontium aluminate-doped polymer substrate capable of high-persistence phosphorescence. The encoding means (12) utilizes a high-precision ultraviolet (UV) laser etching system (e.g., 266 nm Nd:YAG) to selectively "deactivate" phosphorescent particles in the substrate, creating the dark elements of the PDF417 symbol. The recognition means (14) is a specialized scanner (28) that first excites the entire symbol area with a wide-beam UV flash lamp. The converting means is a time-gated CCD or CMOS sensor that captures the afterglow image after the excitation flash is extinguished. The contrast between the glowing and non-glowing (etched) areas provides a high signal-to-noise ratio, making it readable in low-light conditions or through semi-opaque-to-visible-light materials. The decoding logic (30) remains largely the same but must account for potential blooming effects in the phosphorescent image, using edge-detection algorithms like Canny or Sobel to refine the bar-space boundaries before applying the t-sequence analysis.

  • graph TD
        subgraph Encoding Means (12)
            A[Data Input] --> B{Processor & PDF417 Encoder};
            B --> C[266nm Nd:YAG Laser Controller];
            C --> D[Laser Etching Head];
        end
        subgraph Data Carrier (16)
            E[Strontium Aluminate Substrate]
        end
        D --Etches Symbol--> E;
        subgraph Recognition Means (14)
            F[UV Flash Lamp Excites Substrate] --> E;
            E --Emits Afterglow--> G[Time-Gated CCD Sensor];
            G --> H{Image Processor - Edge Detection};
            H --> I[Low-Level Decoder (30)];
            I --> J[Decoded Data Output (32)];
        end
    

2. Operational Parameter Expansion

• Derivative 1.2: Microfluidic Nanoparticle Assembly
  • Enabling Description: This system operates at the micro/nanoscale for tagging biological samples. The "carrier" is a microfluidic channel. The "indicia" are not printed but are self-assembled from metallic nanoparticles (e.g., gold nanoparticles) and inert polymer spacers. The encoding means is a micro-electro-mechanical system (MEMS) that controls voltages at a series of micro-electrodes along the channel. Data from a computer file is converted into a sequence of voltage applications that trap the metallic nanoparticles at specific locations to form the rows of a micro-PDF417 symbol, while the spacers form the white space. The recognition means is a high-magnification microscope coupled with a high-speed camera. The decoding means uses image processing to identify the nanoparticle clusters and their relative spacing, converting the image into a digital representation of the symbol for decoding. This allows for embedding vast amounts of data directly onto a lab-on-a-chip device for tracking single-cell experiments.

  • sequenceDiagram
        participant Encoder as Encoding Control (MEMS)
        participant MChannel as Microfluidic Channel
        participant Decoder as Microscope/Camera System
        Encoder->>MChannel: Inject Nanoparticles & Spacers
        Encoder->>MChannel: Apply Voltage Sequence to Electrodes
        MChannel->>MChannel: Nanoparticles Assemble into PDF417
        Decoder->>MChannel: Capture High-Res Image of Assembled Symbol
        Decoder->>Decoder: Process Image to Extract Bar/Space Widths
        Decoder->>Decoder: Execute PDF417 Decoding Algorithm
        Decoder->>User: Output Decoded Data
    

3. Cross-Domain Application

• Derivative 1.3: Aerospace - Self-Verifying Composite Ply Layup

  • Enabling Description: In the manufacture of aerospace composites, each ply of carbon fiber pre-preg is marked with a PDF417 symbol by the encoding means (12), which is a high-speed, non-contact inkjet printer using a resin-soluble, non-contaminating ink. The symbol encodes the ply number, orientation, material batch number, and expiration date. The recognition means (14) is integrated into the Automated Fiber Placement (AFP) head. A compact CCD imager scans each ply immediately after it is placed on the mold. The decoded data is compared in real-time against the master CAD layup schedule stored in the AFP controller. Any discrepancy (wrong ply, wrong orientation) triggers an immediate machine halt and alerts the operator, preventing catastrophic layup errors. The system ensures full traceability for each ply in the final component.

  • graph TD
        A[CAD Layup Schedule] --> B{AFP Control System};
        B --> C[Inkjet Encoder on Cutting Table];
        C --Prints PDF417--> D(Carbon Fiber Ply);
        E[AFP Head] --Places Ply--> F(Mold);
        D --> E;
        subgraph Recognition System
            G[CCD Imager on AFP Head] --Scans Ply on Mold--> F;
            G --> H{Decoder};
            H --Decoded Ply Data--> B;
        end
        B --Compares Data--> A;
        B --> I{Decision: Continue or Halt?};
    

• Derivative 1.4: AgTech - In-Field Seed Packet Generation

  • Enabling Description: A mobile agricultural system (e.g., mounted on a tractor or drone) includes an encoding means for creating customized seed packets on-the-fly. Based on real-time soil sensor data (moisture, pH, nutrients), a processing means (24) determines the optimal seed varietal, coating, and quantity for a specific micro-plot. This information is encoded into a PDF417 symbol and printed onto a biodegradable packet by a ruggedized thermal printer (26). The same packet is then filled with the prescribed seeds. The recognition means is used later in the season by a scouting drone equipped with a scanner. The drone reads the symbol on the now-degrading packet remnants to correlate the original seed data with observed plant growth and health metrics, creating a detailed feedback loop for precision agriculture algorithms.

  • graph TD
        A[Soil Sensor Data] --> B{On-Board Processor};
        B --Determines Seed Mix--> C(Seed Hopper/Coater);
        B --Generates PDF417 Data--> D(Thermal Printer);
        D --Prints Symbol--> E[Biodegradable Packet];
        C --Fills Packet--> E;
        E --Is Planted--> F(Field);
        G(Scouting Drone) --Scans Field--> F;
        H[Drone's Scanner] --Reads Symbol--> I{Drone's Decoder};
        I --Correlates with Growth Data--> J[Precision Ag Database];
    

• Derivative 1.5: Consumer Electronics - Dynamic Appliance Configuration

  • Enabling Description: A smart appliance (e.g., a microwave oven, as mentioned in the patent) features a small, front-facing camera as its recognition means (14). Food packaging for compatible products includes a PDF417 symbol printed on it (the carrier, 16). The symbol doesn't just contain a simple product ID; it encodes a complex set of instructions, essentially a script (e.g., in JSON or XML format). When the user presents the package to the appliance's camera, it decodes the script. For a microwaveable meal, the script could define a multi-stage cooking process: {"stage1": {"power": "70%", "time": "90s"}, "stage2": {"power": "50%", "time": "120s", "instruction": "Stir now"}, "stage3": {"power": "100%", "time": "60s"}}. The appliance's processor executes this script, providing a perfectly tailored cooking cycle without requiring user input beyond the initial scan. The encoding means (12) is used by the food manufacturer at the time of packaging.

  • sequenceDiagram
        participant Manufacturer as Manufacturer's System
        participant Product as Product Package
        participant Microwave as Smart Appliance
        participant User as User
    
        Manufacturer->>Product: Encodes & Prints PDF417 Cooking Script
        User->>Microwave: Places product inside
        User->>Microwave: Presents package w/ PDF417 to camera
        Microwave->>Microwave: Scans & Decodes Symbol
        Microwave->>Microwave: Parses Cooking Script (e.g., JSON)
        Microwave->>Microwave: Executes Stage 1 (Power: 70%, Time: 90s)
        Microwave->>User: Beeps, Displays "Stir now"
        User->>Microwave: Stirs food
        Microwave->>Microwave: Executes Stage 3 (Power: 100%, Time: 60s)
        Microwave->>User: Beeps, "Cooking Complete"
    

4. Integration with Emerging Tech

• Derivative 1.6: AI-Enhanced Error Correction & Predictive Decoding

  • Enabling Description: The decoding means (30) is augmented with a convolutional neural network (CNN) trained on millions of examples of pristine, damaged, and distorted PDF417 symbols. When the optical scanner (28) provides a raw image signal of a damaged or poorly printed symbol, the traditional decoding algorithm (steps 154-164) is attempted first. If it fails to decode a sufficient number of codewords to use the standard error correction, the raw image data is passed to the CNN. The AI model, rather than just reading bars and spaces, identifies characteristic features of entire codewords and their clusters. It can "in-paint" missing or unreadable portions of the symbol image based on its training, generating a corrected virtual image. This corrected image is then passed back to the standard low-level decoder, allowing it to successfully reconstruct the data matrix. The system can learn and improve its correction capabilities over time.

  • graph TD
        A[Scanner Captures Damaged Symbol] --> B{Low-Level Decoder};
        B --Fails to Decode--> C{AI Correction Module (CNN)};
        C --Processes Raw Image--> D[Corrected Virtual Image];
        D --> B;
        B --Successfully Decodes--> E[High-Level Decoder];
        E --> F[Output Data];
    

• Derivative 1.7: IoT-Enabled Dynamic Data Carrier

  • Enabling Description: The system is used for tracking sensitive cold-chain shipments. The carrier (16) is a shipping container equipped with an IoT sensor package (temperature, humidity, shock) and a low-power e-paper display. The encoding means (12) initially prints a PDF417 symbol on a label containing the manifest and handling instructions. During transit, the IoT sensors monitor the container's environment. If a temperature excursion occurs, the onboard processor automatically re-encodes the PDF417 symbol, adding a new data block with a timestamp and the temperature data. This new symbol is then rendered on the e-paper display. The recognition means (14) at the receiving dock scans the current symbol on the e-paper display. The decoded data provides not only the original manifest but also a verifiable, tamper-evident log of any environmental deviations during the journey.

  • stateDiagram-v2
        [*] --> Initialized
        Initialized --> InTransit: Dispatch
        InTransit: E-Paper displays original PDF417
        InTransit --> InTransit: IoT Sensor records data
        InTransit --> AnomalyDetected: Temperature > Threshold
        AnomalyDetected --> InTransit: Processor updates PDF417 with anomaly data & renders on E-Paper
        InTransit --> Delivered: Arrives at Destination
        Delivered --> [*]: Scanned by Recognition Means
    

• Derivative 1.8: Blockchain-Verified Chain of Custody

  • Enabling Description: The system is integrated into a supply chain for high-value goods (e.g., pharmaceuticals, luxury items). At each handoff point, an operator uses an encoding device (12) to generate a PDF417 symbol. This symbol contains a hash of the previous transaction block, the current timestamp, GPS location, and the recipient's digital signature. The symbol is printed on a tamper-evident label affixed to the item. A recipient uses a recognition device (14) to scan the symbol. The decoding means (30) extracts the data, verifies the digital signature, and calculates the hash. This data is then submitted as a new transaction to a distributed ledger (blockchain). This creates an immutable, physically-linked chain of custody. Any attempt to alter a label or create a fraudulent one would result in a hash mismatch that is instantly detectable by the next recipient in the chain.

  • sequenceDiagram
        participant PointA as Shipper
        participant Item as Physical Item
        participant PointB as Receiver
        participant Blockchain as Distributed Ledger
    
        PointA->>Item: Generates & Attaches PDF417 Label 1 (Block N)
        PointB->>Item: Scans PDF417 Label 1
        PointB->>Blockchain: Submits Transaction N (Data from Label 1)
        Blockchain-->>PointB: Transaction N Confirmed
        PointB->>Item: Generates & Attaches PDF417 Label 2 (Block N+1, hashes Block N)
        PointB->>Blockchain: Submits Transaction N+1 (Data from Label 2)
    

5. The "Inverse" or Failure Mode

• Derivative 1.9: Graceful Degradation Mode for Emergency Services

  • Enabling Description: The system is used for patient identification wristbands in a mass casualty incident. The PDF417 symbol is structured with a "critical data block" and multiple "secondary data blocks." The critical block, always located in the first three rows of the symbol, contains only the patient's unique ID, blood type, and critical allergies, and it uses the highest level of error correction (e.g., Level 8). Secondary blocks contain less critical information like home address or primary physician, with lower error correction. The recognition means (14), when switched to "Triage Mode," performs a low-resolution, high-speed scan. Its decoding algorithm (30) is programmed to only search for and decode the first three rows containing the critical data block. This allows first responders to rapidly identify dozens of patients in seconds, ignoring the secondary data. In "Full-Record Mode," the scanner performs a more detailed scan to capture and decode the entire symbol. This provides a fail-safe where essential information is prioritized and readable even if the symbol is partially obscured or damaged.

  • graph TD
        subgraph PDF417 Symbol
            A[Rows 0-2: Critical Data Block - High ECC]
            B[Rows 3-N: Secondary Data - Low ECC]
        end
        subgraph Scanner
            C{Mode Selection};
            C -- Triage Mode --> D[High-Speed, Low-Res Scan];
            C -- Full-Record Mode --> E[Standard Scan];
            D --> F{Decode Critical Block Only};
            E --> G{Decode Full Symbol};
            F --> H[Output: ID, Blood Type, Allergies];
            G --> I[Output: Full Patient Record];
        end
    

• Derivative 1.10: Self-Redacting Privacy Symbol

  • Enabling Description: The system is used for temporary identification or access control. The data carrier (16) is a "smart paper" substrate a thermochromic ink layer over the printed PDF417 symbol (18). The symbol is printed using standard ink. A transparent, resistive heating element is laminated over the symbol. The recognition means (14) is a specialized reader that, in addition to the optical scanner, contains a power-driver circuit. After a successful scan and decode, the decoding means (30) sends a signal to the power-driver circuit. This circuit applies a brief, low-voltage pulse to the heating element, raising the temperature of the thermochromic ink just enough to turn it opaque (e.g., from clear to black), permanently redacting the underlying PDF417 symbol and preventing any further reads. This provides a single-use, physically secure method for data transfer where the data carrier self-destructs its information after use.

  • flowchart TD
        Start --> A[Present Carrier to Reader];
        A --> B{Scan and Decode PDF417 Symbol};
        B -- Success --> C{Authenticate Data/Grant Access};
        C --> D{Send 'Redact' Signal};
        D --> E[Apply Voltage to Heating Element];
        E --> F[Thermochromic Ink Turns Opaque];
        F --> G[Symbol is Now Unreadable];
        G --> End;
        B -- Failure --> H[Deny Access / No Redaction];
        H --> End;
    

---

Combination Prior Art Scenarios

1. Combination with OpenCV (Open Source Computer Vision Library)

• Scenario: A robust, open-source decoding system for mobile platforms.
• Enabling Description: A software library is created that leverages the core algorithms of the '655 patent but is implemented using functions from the open-source OpenCV library. The cv::VideoCapture function is used to acquire a continuous video stream from a smartphone camera. Each frame is converted to grayscale. The cv::Canny edge detection and cv::findContours functions are used to rapidly locate potential barcode regions within the frame, replacing the patent's described method of searching for start/stop patterns in a linear scan. Once a candidate region is identified, its perspective is corrected using cv::getPerspectiveTransform and cv::warpPerspective to produce a flat, rectangular image of the symbol. This normalized image is then binarized, and the core decoding logic from the '655 patent—identifying codewords, calculating cluster numbers, assigning row numbers based on row indicators, and populating the codeword matrix—is applied to decode the data. This combination makes the robust "stitching" decoding of PDF417 available in a royalty-free, high-performance library accessible to any developer.

• sequenceDiagram
      participant App as User Application
      participant Camera as Device Camera
      participant OpenCV as OpenCV Library
      participant PDF417Decoder as '655 Logic Core
  
      App->>Camera: Start Capture
      loop Frame Processing
          Camera->>OpenCV: Provides Video Frame
          OpenCV->>OpenCV: Grayscale, Canny Edge, findContours
          OpenCV-->>App: Bounding Box of Symbol
          App->>OpenCV: Warp Perspective on Bounding Box
          OpenCV-->>App: Normalized Symbol Image
          App->>PDF417Decoder: Pass Normalized Image
          PDF417Decoder->>PDF417Decoder: Decode using 'Stitching' Logic
          PDF417Decoder-->>App: Decoded Data or Failure
      end
  

2. Combination with IETF RFC 7519 (JSON Web Tokens - JWT)

• Scenario: A system for physically verifiable, offline digital identity or authorization tokens.
• Enabling Description: A server-side application generates a standard JSON Web Token (JWT) containing user claims (e.g., user ID, roles, expiration time) and signs it with a private key. Instead of transmitting this JWT electronically, the entire Base64URL-encoded string (header.payload.signature) is passed to the encoding means (12) of the '655 patent system. The data is encoded into a high-density PDF417 symbol and printed onto a physical ID card or a single-use ticket. A client-side recognition means (14), such as a secure kiosk or mobile device, scans the PDF417 symbol. The decoding means (30) extracts the JWT string. The client then performs standard JWT validation: it checks the signature using the corresponding public key, verifies the expiration timestamp (exp), and parses the payload to grant access or confirm identity. This allows for a stateless, secure, offline authentication mechanism where the physical token is the "single source of truth."

• graph LR
      subgraph ServerSide
          A[User Data] --> B{JWT Creation};
          B -- "header.payload.signature" --> C{PDF417 Encoder};
          C --> D[Printer];
      end
      D -- Prints --> E(Physical ID Card with PDF417);
      subgraph ClientSide
          F[Scanner/Camera] -- Scans --> E;
          F --> G{PDF417 Decoder};
          G -- "JWT String" --> H{JWT Validator};
          H -- Uses Public Key --> I[Signature & Claim Verification];
          I --> J[Access Granted/Denied];
      end
  

3. Combination with G-code (RS-274 Standard)

• Scenario: A "paper-based programming" system for CNC machines and 3D printers.
• Enabling Description: A Computer-Aided Manufacturing (CAM) software package is modified to include an output option for "Paper G-code." When selected, the CAM software generates the G-code toolpath instructions for a machining operation. This text-based G-code file is then fed into the encoding means (12) of the '655 patent system and encoded into a large PDF417 symbol. The symbol is printed (26) on a durable, oil-resistant label (the carrier, 16). An operator affixes this label directly to the raw material stock. The CNC machine is retrofitted with a recognition means (14) consisting of a simple fixed-mount camera and a microcontroller (e.g., a Raspberry Pi). Before starting the job, the operator positions the material and initiates a scan. The recognition means scans the PDF417 symbol, decodes it back into the original G-code text file, and loads it directly into the CNC controller's memory for execution. This eliminates the need for network connections, USB drives, or manual data entry on the factory floor, reducing the risk of loading the wrong file for a given piece of stock.

• flowchart TD
      subgraph Office
          A[CAD Model] --> B[CAM Software];
          B -- Generates G-code --> C{PDF417 Encoder};
          C -- Encoded Data --> D[Printer];
          D --> E[Print G-code PDF417 Label];
      end
      subgraph Factory Floor
          F[Operator] -- Affixes Label --> G(Raw Material Stock);
          G -- Placed in Machine --> H[CNC Machine];
          I[Camera on CNC] -- Scans Label --> J{PDF417 Decoder};
          J -- Decoded G-code --> K[CNC Controller];
          K -- Executes Program --> L[Machined Part];
      end