Image Reader Guiding Unit for Stiff Document Transport
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Solution Overview
Problem
Existing image readers face issues with abnormal document transport due to belly contact between the document leading end and the transport roller, particularly when the document has high stiffness, leading to inefficient reading and potential damage.
Innovation Solution
The image reader incorporates a guiding unit that switches between two states based on document thickness, guiding the leading end to either a higher position on the transport roller's outer surface or a lower position, ensuring appropriate nipping and reducing belly contact, while maintaining cost-effectiveness by eliminating the need for a dedicated state-switching unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the document holder is disposed on a lower side and the image sensor is disposed on an upper side to enable face-up document feeding, then the ease of operation is improved, but belly contact of the document leading end with the transport roller occurs causing abnormal transport
Solution Approach 1:
The lower guide surface is positioned at a height lower than the highest position of the transport roller outer circumferential surface, and the guiding unit is provided downstream to guide the document leading end to a higher position on the roller surface before nipping occurs. This preliminary positioning action prevents belly contact by ensuring the document leading end approaches the nip point at the correct height.
Solution Approach 2:
The guiding unit acts as an intermediary element between the lower guide surface and the transport roller. It mediates the document leading end's position, transitioning it from the lower guide surface level to the appropriate height on the roller outer circumferential surface, thereby preventing direct belly contact with the roller.
2Reliability
If the guiding unit guides the document to a higher position on the transport roller to suppress belly contact, then transport reliability is improved, but the feeling of contact is reduced making document insertion less detectable
Solution Approach 1:
The guiding unit is configured to switch between a first state where it guides the document to a higher position on the roller (suppressing belly contact) and a second state where it guides the document to a lower position (providing strong contact feeling). This dynamic adjustment allows the system to adapt to different document types and insertion scenarios, maintaining both transport reliability and operational feedback.
Data Source
AI summary
An image reader includes: a document transport path through which a document to be read is transported; a transport roller that is provided on a lower side in the document transport path and is driven to apply a feed force to the document. The lower side of the document transport path upstream from the transport roller is at a position that is lower than a highest position of an outer circumferential surface of the transport roller and is formed on a lower guide surface guiding the document to the transport roller. A guiding unit is provided downstream from the lower guide surface and guides the document from the lower guide surface to a position on the outer circumferential surface of the transport roller, the position being higher than the lower guide surface.