Document Reader Roller Control for Stability
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Solution Overview
Problem
Document readers with transport units face issues where larger documents may fall from discharge trays due to size mismatch, leading to deformation and reduced reading accuracy.
Innovation Solution
A document reader with a control unit that stops the rotation of a second roller pair downstream of the reading position, ensuring the document is nipped and held securely regardless of size, reducing the risk of falling and deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the paper discharge tray is made small to reduce device size, then device compactness is improved, but documents may fall from the tray causing deformation
Solution Approach 1:
The system dynamically controls the transport roller to stop at different positions based on document size detection. For large documents, the roller stops earlier to prevent overhang and falling, while for small documents, it can stop closer to the discharge end. This dynamic adjustment resolves the contradiction between compact tray size and document stability.
Solution Approach 2:
The control unit changes the stopping position parameter of the transport roller based on the detected document dimensions. By adjusting this parameter, the system optimizes document placement on the discharge tray for different sizes, preventing falls while maintaining compact device design.
2Productivity
If the document transport speed is increased to improve productivity, then reading efficiency is improved, but document positioning accuracy deteriorates
Solution Approach 1:
The transport roller operates with periodic acceleration and deceleration phases. During the reading phase, it maintains a controlled speed for accurate positioning, then accelerates for the transport phase to improve overall productivity. This periodic speed variation resolves the contradiction between reading efficiency and positioning accuracy.
3Stability of the object's composition
If the roller nipping force is increased to prevent document falling, then document stability is improved, but document deformation increases
Solution Approach 1:
The system applies different nipping forces at different locations and times: strong nipping force during transport to prevent falling, and reduced or zero nipping force during the reading phase to avoid deformation. This localized and temporal differentiation of force application resolves the contradiction between stability and shape preservation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively prevents document falling and deformation, maintaining reading accuracy and reducing user intervention for document handling.
Implementation Method 1
a first roller pair configured to nip and transport the document medium
Data Source
AI summary
A document reader includes a reading unit that reads an image of a document medium, a second driving roller pair that nips and transports the document medium downstream of a read-enabling position of the reading unit, and a control unit that controls rotation of the second driving roller pair. The control unit stops the rotation of the second driving roller pair in a state in which the document medium is not positioned in the read-enabling position and in a state in which the document medium is nipped by the second driving roller pair.