White Reference Member Posture Control for Shading Accuracy
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Solution Overview
Problem
Conventional sheet-through type image reading apparatuses face accuracy deterioration in shading correction due to soiling of the white reference roller, as the white reference surface can be inadvertently exposed and soiled during maintenance or paper jam removal, leading to incorrect brightness correction.
Innovation Solution
An image reading apparatus with a white reference member attached to a cover member that can be opened and closed, featuring a driving unit that changes the posture of the white reference member between operating and non-operating states, and a locking mechanism that prevents the white reference member from being rotated into the operating posture during cover member opening, ensuring the white reference surface remains protected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the white reference roller is made to rotate during cover member opening, then the driving transmission system allows cover opening operation, but the white reference surface may be inadvertently exposed and soiled
Solution Approach 1:
The white reference surface is extracted from the rotating roller and placed on a stationary member, separating the reference function from the rotating component. This prevents the reference surface from being exposed during cover opening while maintaining the roller's rotation capability for document transport.
Solution Approach 2:
A stationary white reference member is introduced as an intermediary element to provide the reference surface. This mediator allows the cover to open without rotating the roller, while still providing the necessary white reference for shading correction through optical coupling.
2Reliability
If the white reference roller is stationary, then the white reference surface remains protected, but the roller cannot be rotated to bring the white reference portion opposite the image reading portion
Solution Approach 1:
The system is segmented into a stationary white reference member and a separate rotating roller. The stationary member provides the reference surface that remains protected, while the roller can still rotate independently to transport documents, with the reference surface positioned to be readable by the image reading portion when needed.
3Productivity
If the white reference portion is formed on the rotating roller, then shading correction can be performed, but the white reference surface is easily soiled by document contact
Solution Approach 1:
The white reference surface is extracted from the rotating roller and placed on a stationary member that does not contact documents. This separation eliminates the harmful contact between the reference surface and documents while preserving the shading correction function.
Solution Approach 2:
The white reference function is copied from the rotating roller to a stationary member. The stationary member provides an identical white reference surface for shading correction purposes, but without the mechanical contact issues of the rotating roller.
Data Source
AI summary
An image reading apparatus 4 includes an image reading portion 38 which is unmovably arranged at one side with respect to a document transportation path 30, a white reference member 43 for shading correction which is arranged at the other side with respect to the document transportation path 30, a cover member 50 which is capable of being opened and closed so as to expose or cover the document transportation path 30, and a driving unit 55 which changes a posture of the white reference member 43 between an operating posture at the time of the shading correction and a non-operating posture. The white reference member 43 is attached to the cover member 55. Further, the white reference member 43 and the driving unit 55 are related to each other such that the white reference member 43 is not made into the operating posture in conjunction with an opening operation of the cover member 55.