Image Reading Roller Path for Thick-Paper Flattening
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Solution Overview
Problem
Existing image reading devices face challenges in optimizing the posture of transported media, particularly for thick papers, leading to feeding failures and reduced reading accuracy due to insufficient flattening of media with a letter-V shape.
Innovation Solution
The device employs a feeding unit with a narrow nipping width, followed by first and second transport roller pairs with progressively wider nipping widths to flatten the medium, and includes a configuration where the first transport roller pair's rotary shafts form a specific angle to optimize medium posture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the medium is excessively bent in the feeding unit, then the letter-V shape deformation is corrected, but thick paper cannot be appropriately transported
Solution Approach 1:
The transport path is divided into multiple segments with different nipping widths: the feeding unit uses a narrow nipping width to preserve medium shape, while the first and second transport roller pairs use progressively wider nipping widths to gradually flatten the medium. This segmented approach allows different regions of the transport system to perform different functions, resolving the contradiction between shape correction and transport reliability.
Solution Approach 2:
The feeding unit performs preliminary transport with a narrow nipping width before the medium enters the flattening section. This preliminary action preserves the medium's letter-V shape during initial transport, allowing subsequent roller pairs to gradually flatten it without causing feeding failures, thus preparing the medium for successful transport through the entire system.
2Measurement precision
If the medium is sufficiently flattened in the feeding unit, then reading accuracy is improved, but the device complexity increases
Solution Approach 1:
Instead of using a single complex feeding unit with wide nipping width for immediate flattening, the system segments the flattening function across multiple roller pairs positioned at different locations. The first transport roller pair and second transport roller pair progressively flatten the medium as it moves through the system, achieving high reading accuracy without requiring the feeding unit itself to be overly complex.
3Shape
If a single roller pair with wide nipping width is used, then medium flattening is achieved, but device size increases
Solution Approach 1:
The flattening function is segmented across multiple compact roller pairs rather than requiring one large roller pair. Each roller pair contributes partially to the flattening process, allowing the medium to be gradually flattened through successive sections. This distributed approach achieves the same flattening effect while maintaining a more compact overall device size.
Solution Approach 2:
The system uses multiple roller pairs arranged along the transport direction (one dimension) to achieve flattening, rather than relying on a single wide roller pair that would increase width (another dimension). This dimensional redistribution allows effective flattening while minimizing the device's footprint in terms of overall volume.
Data Source
AI summary
An image reading device includes a feeding unit including a feeding roller and a separation roller, a first transport roller pair disposed downstream of the feeding unit in a transport direction, a second transport roller pair disposed downstream of the first transport roller pair in the transport direction, and a reading unit disposed downstream of the second transport roller pair in the transport direction, in which the feeding unit transports the medium while nipping the medium with a nipping width narrower than a width of the medium, the first transport roller pair transports the medium while nipping the medium with a nipping width wider than the nipping width of the feeding unit, and the second transport roller pair transports the medium with a nipping width wider than the nipping width of the first transport roller pair using a plurality of roller pairs.