Medium Feeding Apparatus Multi-Feed Prevention via Position Detection
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Solution Overview
Problem
Existing medium feeding apparatuses face challenges in preventing multi-feed, where two or more media are fed together, due to limitations in detecting and separating individual sheets accurately.
Innovation Solution
A medium feeding apparatus that includes a media tray, a feed roller, a separation roller, and circuitry to detect the leading end position of each medium in the nip between the rollers. The apparatus determines the distance between the leading ends of successive media and sets a characteristic value for the separation roller based on this distance to prevent multi-feed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sensor detects the number of sheets at the nip or downstream to prevent multi-feed, then the occurrence of multi-feed is reduced, but the detection accuracy of leading end position deteriorates
Solution Approach 1:
The patent transitions from one-dimensional detection (counting sheets at a single nip position) to two-dimensional detection (imaging the leading ends of multiple sheets at different positions simultaneously). The area sensor captures images of sheet leading ends at various locations, enabling precise position detection while maintaining multi-feed prevention capability.
Solution Approach 2:
The patent introduces an imaging system as an intermediary between the sheets and the detection mechanism. Instead of directly sensing sheet presence at the nip, the area sensor optically images the leading ends of sheets, providing precise position information without interfering with the feeding process.
2Reliability
If the separation roller's pressure-contact load or separation torque is adjusted to match the second sheet position to target value, then multi-feed is prevented, but the system complexity increases
Solution Approach 1:
The patent implements a feedback control system where the area sensor detects the actual position of sheet leading ends, the control unit compares this with the target position, and automatically adjusts the separation roller's separation torque to correct any deviations. This closed-loop feedback mechanism prevents multi-feed while maintaining system simplicity through automated control.
3Adaptability or versatility
If the feeding rotator is moved to retracted position based on sheet size detection, then sheet size adaptability is improved, but the feeding speed deteriorates
Solution Approach 1:
The patent performs preliminary detection of sheet leading end positions using the area sensor before the feeding process begins. By acquiring position information in advance, the system can pre-calculate the appropriate retraction distance for the feeding rotator, enabling rapid adaptation to different sheet sizes without slowing down the overall feeding process.
Data Source
AI summary
A medium feeding apparatus includes a media tray, a feed roller to sequentially feed a plurality of media placed on the media tray, a separation roller located facing the feed roller, and circuitry. The circuitry detects a leading end position of each of a plurality of media in a nip between the feed roller and the separation roller, determines a distance between a leading end position of a preceding medium, which is of the plurality of media in the nip, and a leading end position of a medium following the preceding medium, and sets a characteristic value of the separation roller based on the distance.