Scanner Glass Support Layout for Accurate Document Reading
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Solution Overview
Problem
The bending of a transparent glass plate due to the load applied from abutment portions of a conveyance unit in an image reading apparatus can deteriorate image reading accuracy.
Innovation Solution
An image reading apparatus with a support structure that includes multiple support portions on either side and in between abutment portions to stabilize the transparent glass plate, reducing bending and maintaining accurate positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the conveyance unit is closed with abutment portions pressing against the transparent glass plate to maintain positioning, then the relative position between the image reading unit and conveyance unit is kept proper, but the glass plate bends due to the applied load, deteriorating image reading accuracy
Solution Approach 1:
The support structure is divided into multiple discrete support portions (first support portion, second support portion, third support portion, and fourth support portion) positioned at different locations on the glass plate. This segmentation distributes the load from the abutment portions across multiple contact points, preventing concentrated stress that would cause bending while maintaining positioning accuracy.
Solution Approach 2:
Support portions are strategically positioned at specific locations: the first and second support portions are located outside the range between abutment portions, while the third and fourth support portions are positioned within that range. This local placement optimizes structural support exactly where needed to counteract bending forces without interfering with the overall positioning function.
2Ease of manufacture
If the light-transmissive member is made thinner to reduce weight and cost, then ease of manufacture improves, but the member becomes more susceptible to bending under load from abutment portions
Solution Approach 1:
The support portions are pre-positioned on the frame before the conveyance unit is closed. This preliminary support structure is already in place to counteract the expected load from abutment portions, preventing bending from occurring in the first place rather than attempting to correct it after deformation.
Solution Approach 2:
The support portions act as intermediary elements between the frame and the transparent glass plate. They mediate the force transmission from the abutment portions, distributing the load through the frame structure rather than allowing it to concentrate on the glass plate, thereby preventing bending while maintaining manufacturing simplicity.
Data Source
AI summary
An image reading apparatus includes a reading unit including a frame, a transparent glass plate, and an image sensor, and a conveyance unit including a plurality of conveyance rollers. The conveyance unit includes (i) a first abutment portion and (ii) a second abutment portion, and is configured such that the first abutment portion and the second abutment portion abut a first surface of the transparent glass plate in a state where the conveyance unit is closed. The frame includes a first support portion, a second support portion, a third support portion, and a fourth support portion.