Automatic Document Feeder Duplex Scanning Efficiency
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Solution Overview
Problem
Conventional automatic document feeders in image forming apparatuses have low printing efficiency in duplex printing mode due to the need for documents to pass through the duplex scan path twice, which limits the ability to increase efficiency beyond 40% of single printing mode efficiency.
Innovation Solution
The automatic document feeder is designed with separate document discharge, first document reversing, and second document reversing passages to allow for efficient collation and discharge of scanned documents, enabling the next document to be scanned without overlapping paths, using a document guide unit with movable guides and a rotation driving unit to manage different scanning modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the document passes through the duplex scan path twice to collate and discharge scanned documents, then the document can be properly collated in the same page as admission, but the printing efficiency in duplex printing mode becomes very low (no more than 40% of single printing mode efficiency)
Solution Approach 1:
The patent divides the document path into separate segments: a first document path for admitting documents and a second document path for discharging documents. The duplex scan path is configured to connect these separate paths, allowing documents to be scanned on both surfaces and discharged without needing to pass through the duplex scan path twice. This segmentation resolves the contradiction by maintaining collation accuracy while improving printing efficiency to approximately 90% of single printing mode efficiency.
2Productivity
If the duplex scan path is shortened and conveying roller is moved away from backup roller to increase efficiency, then the document admission interval is reduced, but the document still needs to pass through the duplex scan path again to collate and discharge
Solution Approach 1:
The patent extracts the document discharge function from the duplex scan path by providing a separate second document path. The duplex scan path is configured to discharge scanned documents to this separate path, eliminating the need for documents to pass through the duplex scan path twice. This extraction maintains document collation accuracy while enabling continuous operation and improving printing efficiency.
3Device complexity
If the same document path is used for both document admission and discharge in duplex mode, then the device structure is simplified, but the document admission interval increases and printing efficiency decreases
Solution Approach 1:
The patent applies local quality by providing different path configurations for different functions: the first document path is optimized for document admission with appropriate conveying rollers, while the second document path is optimized for document discharge. The duplex scan path connects these paths at specific locations to enable efficient duplex scanning. This localized optimization maintains manageable device complexity while achieving approximately 90% printing efficiency in duplex mode.
Data Source
AI summary
An automatic document feeder of an image forming apparatus capable of improving a duplex scanning or printing (copying) efficiency includes a single scan path having a document admission passage to admit a document to a document scanning part and a document discharge passage to discharge the scanned document, a duplex scan path having a first document reversing and waiting passage diverged separately from the document discharge passage on the single scan path at the rear of the document scanning part to reverse the document, one surface of which is scanned, and admit the reversed document again to the document scanning part, and a document re-reversing path having a second document reversing and waiting passage diverged separately from the document discharge passage on the single scan path at the rear of the document scanning part to reverse the document, both surfaces of which are scanned, again and send the re-reversed document to the document discharge passage.