USB Isochronous Laser Printer Data Transfer Error Correction
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Solution Overview
Problem
Current USB standard isochronous mode lacks error correction for real-time transfer of laser printer scan data, necessitating significant buffering of data in laser printer memory to ensure continuous printing, which is resource-intensive.
Innovation Solution
The method involves breaking laser printer scan data into packets, deriving parity packets through XOR operations, and using checksums from hash functions like cyclic redundancy check (CRC) to detect and correct errors during transmission over USB, allowing for continuous and uninterrupted data stream to the printer's video hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If USB standard isochronous mode is used for data transfer, then data transfer speed is sufficient for laser printer, but error correction capability is lacking making it unsuitable for real-time transfer
Solution Approach 1:
The patent introduces an intermediary error correction mechanism that operates between the USB isochronous data transfer and the laser printer video hardware. This intermediary layer includes: (1) A data packetization module that segments scan data into manageable packets with embedded error detection codes; (2) A dual-buffer system (first buffer and second buffer) that enables error correction processing without interrupting the continuous data stream to video hardware; (3) An error correction algorithm that operates on buffered packets and reconstructs corrupted data using redundancy information. This intermediary error correction system allows the use of fast USB isochronous mode while ensuring data integrity through real-time error detection and correction.
2Reliability
If error correction is implemented during USB data transfer, then data reliability is improved, but memory buffering requirements increase significantly
Solution Approach 1:
The patent segments the scan data into smaller data packets that can be processed independently through the error correction mechanism. Each packet is divided into data portions and redundancy portions, allowing error correction to operate on small units rather than requiring buffering of entire pages. This segmentation enables the error correction system to work with minimal buffering (only one packet worth of data needs to be buffered at a time) while still providing comprehensive error protection across the entire scan data stream.
3Reliability
If significant buffering is performed at the printer, then error correction can be achieved, but demand on laser printer memory becomes heavy
Solution Approach 1:
The patent implements partial error correction by applying error detection and correction codes to only the essential scan data packets that are currently being processed or buffered, rather than requiring all scan data to be buffered and corrected before printing. The dual-buffer system maintains only one packet of data in the first buffer and processes it through error correction, while the second buffer receives the next packet. This partial action approach provides sufficient error protection for the continuous printing process without requiring excessive memory resources for buffering entire pages.
Data Source
AI summary
A system, method, and processor executable instructions to isochronously communicate in standard USB mode laser printer scan data from a host computer to a laser printer. The host computer transmits a data stream that includes data packets having laser printer scan data, error detection information, and correction packets such as parity packets for use to reconstruct packets having an error. The laser printer receives the data stream, processes the error detection information, data packets and parity packets, and provides a continuous stream of laser printer scan data for printing.