Document Feeding Apparatus with Dual Detection for Small Media
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Solution Overview
Problem
Automatic document feeders (ADFs) struggle to accurately detect and feed small documents like business cards and bank checks due to static electricity and friction, leading to documents becoming stuck or erroneously detected as absent, resulting in feeding failures.
Innovation Solution
A document feeding apparatus with a document tray, a feed roller, a separation conveying unit, and a dual detecting system using flag members and photo-interrupters to differentiate document presence and absence before and after the feed roller lowers, ensuring accurate detection and feeding of small documents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple small documents are fed into the ADF, then the document feeding capability is improved, but static electricity and friction cause documents to stick together, leading to feeding errors
Solution Approach 1:
The patent applies preliminary anti-action by introducing a separation conveying unit that actively prevents documents from sticking together before the feeding error can occur. The separation conveying unit conveys documents one by one, ensuring they are separated individually, which counteracts the sticking effect caused by static electricity and friction between documents
2Reliability
If the second document reaches the separating-conveying portion due to sticking, then document separation is attempted, but the document is pinched and floats from the tray, causing detection errors
Solution Approach 1:
The patent introduces an intermediary detection mechanism (first detecting unit with flag member) that acts as a mediator between the document feeding process and the control system. This detecting unit positioned at the first detecting position provides advance warning of document presence, allowing the system to control the feed roller appropriately and prevent pinching and floating errors
3Device complexity
If a single detection position is used, then the device complexity is reduced, but the ability to detect document presence accurately before and during feeding is insufficient
Solution Approach 1:
The patent applies segmentation by dividing the detection function into two distinct detection positions: a first detecting position (upstream) for advance document presence detection, and a second detecting position (downstream) for confirming document presence during feeding. This segmentation allows the system to execute different detection processes at appropriate times, improving overall detection accuracy without excessive complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces the likelihood of document floatation and feeding errors, ensuring that small documents are correctly detected and fed into the image reading apparatus, improving the reliability of the document feeding process.
Implementation Method 1
a first detecting unit provided with a flag member movable so as to change a protrusion amount by which the flag member protrudes from the document placement surface... configured to detect that the document is at the first detecting position
Data Source
AI summary
A document feeding apparatus includes a document tray, a feed roller, a separation conveying unit, a first detecting unit and a control unit. The first detecting unit detects that the document is at the first detecting position when a protrusion amount of a flag member is a first amount and detects that no document is at the first detecting position when the protrusion amount is a second amount. The control unit executes an operation in a first mode in which a first detecting process is executed so as to detect the presence or absence of the document before starting to lower the feed roller and the presence or absence is determined, and in a second mode in which a second detecting process is executed so as to detect the presence or absence at the first detecting position after lowering said feed roller and the presence or absence is determined.