Duplex Paper Path Scheduling for Faster Collision-Free Printing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Duplex printers experience reduced printing speed due to the need for paper flipping, limiting actual speed to less than 15 IPM despite a theoretical single-sided speed of 30 PPM.
Innovation Solution
A multi-page circulating duplex printing method that optimizes transporting paths by partially transporting documents in and out of passages and controlling timings to prevent collisions, allowing concurrent document presence in multiple passages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional duplex printing with sequential paper flipping is used, then document order is maintained, but printing speed decreases to less than 15 IPM
Solution Approach 1:
The patent segments the printing process into multiple independent circulation paths (first passage and second passage), allowing different documents to be processed simultaneously in different segments. This parallelization eliminates the sequential bottleneck of traditional single-path duplex printing, enabling the printer to achieve 24 IPM by having multiple documents in various stages of printing and flipping at the same time.
Solution Approach 2:
The patent implements preliminary action by transporting documents partially out and back before complete printing is finished. Documents are pre-positioned in circulation paths and prepared for flipping in advance, so that when one side is complete, the document is already in position for immediate reversal and printing of the other side, eliminating idle waiting time.
2Productivity
If multiple documents are transported concurrently in multiple passages, then printing speed increases, but risk of document collisions increases
Solution Approach 1:
The patent employs periodic action through synchronized timing control of document transport in multiple passages. Each passage operates on a coordinated schedule where documents are transported, flipped, and returned at predetermined intervals. This periodic synchronization ensures that documents occupy different positions in the circulation paths at different times, preventing collisions while maintaining high throughput.
Solution Approach 2:
The patent implements feedback control through timing coordination that monitors the position and status of documents in each passage. The system adjusts the timing of transport and flipping operations based on the state of other passages, creating a feedback loop that prevents document collisions while maximizing concurrent processing. The coordinated timing ensures that when one passage is transporting a document, other passages are at safe positions.
Data Source
AI summary
A printing method includes: printing a front side of a first document, and then transporting, from a first passage, the first document partially out and back to a reverse passage; printing a front side of a second document, and then transporting, from a second passage, the second document partially out and back to the reverse passage; printing a front side of a third document, and then transporting, from the first passage, the third document partially out and back to the reverse passage; printing a reverse side of the first document, and then transporting, from the second passage, the first document to a discharge tray; printing a reverse side of the second document, and then transporting, from the second passage, the second document to the discharge tray; and printing a reverse side of the third document, and then transporting, from the second passage, the third document to the discharge tray.