Image Reading Apparatus Conveyance Path Gap Stabilization
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Solution Overview
Problem
Existing image reading apparatuses face issues with conveyance failure and image distortion when handling thick or thin papers due to the narrowing of the conveyance path gap at the second reading position, caused by the weight-induced sinking of the sheet conveyance unit, leading to potential jamming and image defects.
Innovation Solution
The image reading apparatus incorporates a conveyance path securing portion with projection members that abut against the transparent members from the non-sheet passing area, securing the gaps between the main body unit and the sheet conveyance unit at multiple positions along the conveyance path to maintain a stable and accurate clearance, preventing the sinking of the sheet conveyance unit and ensuring consistent image reading across both surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the gap is secured by projections abutting against the transparent member at the first reading portion side, then the positioning of the sheet conveyance unit is improved, but the sheet conveyance unit sinks down at the second reading portion side by its own weight, causing the gap to narrow and leading to conveyance failure or image defects
Solution Approach 1:
The gap securing function is divided into multiple segments: projections at the first reading portion secure the gap upstream, while additional projections at the second reading portion secure the gap downstream. This segmentation allows each projection set to independently maintain gap stability at its respective location, preventing the sinking issue that occurs with single-point securing.
Solution Approach 2:
Additional projection members are introduced as intermediary elements between the sheet conveyance unit and the main body unit at the second reading portion. These projections act as mediators to maintain the gap clearance, compensating for the weight-induced sinking and ensuring consistent gap positioning throughout the entire conveyance path.
2Weight of moving object
If the sheet conveyance unit is designed to be lightweight, then the sinking issue is reduced, but the structural strength and stability of the sheet conveyance unit may be compromised
Solution Approach 1:
Instead of uniformly reducing the weight of the entire sheet conveyance unit, the invention applies local quality by adding projections only at specific locations (first and second reading portions) where gap securing is needed. This allows the main body to remain lightweight while providing localized structural reinforcement exactly where required to prevent sinking and maintain gap stability.
Solution Approach 2:
The sheet conveyance unit employs asymmetric structural features with projections positioned at different locations along the conveyance path. The projections are strategically placed at the first reading portion and second reading portion to create an asymmetric support distribution that counteracts the weight-induced sinking without requiring symmetric reinforcement throughout the entire structure, thus maintaining light weight while providing necessary strength.
Data Source
AI summary
An image reading apparatus includes a projection portion arranged between a first reading position of a first image reading portion and a second reading position of a second image reading portion in a sheet conveyance direction. The projection portion projects from one of an upper surface of a main body unit and a lower surface of a sheet conveyer and is arranged outside an area through which a sheet on a conveyance path passes in a width direction orthogonal to the sheet conveyance direction. A gap of the conveyance path in a height direction between the upper surface of the main body unit and the lower surface of the sheet conveyer is secured by the projection portion abutting against the other of the upper surface and the lower surface outside the area.