Shading Roller Drive Mechanism for Document Conveying
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Solution Overview
Problem
Existing document conveying devices face challenges in shading correction for rear surface reading units, requiring additional drive sources which increase manufacturing costs and risk document ejection issues when the shading member rotates during paper ejection.
Innovation Solution
A document conveying device that uses a single drive motor to rotate the paper ejection roller and shading roller in opposite directions, with the shading roller driven only when the paper ejection roller rotates in the second direction, and not driven when it rotates in the first direction, allowing for efficient shading correction without additional drive sources and preventing document retraction into the conveying path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a drive source is added to move the white reference member for shading correction, then shading correction can be performed, but the number of drive sources increases and manufacturing cost increases
Solution Approach 1:
The patent applies the universality principle by enabling the paper ejection roller to perform dual functions: (1) ejecting documents after reading, and (2) rotating the white reference member for shading correction. The single drive source that drives the paper ejection roller is also connected to the white reference member through a transmission mechanism, allowing the same drive source to control both document ejection and shading correction operations, thereby reducing the total number of drive sources and lowering manufacturing costs
Solution Approach 2:
The patent merges the function of moving the white reference member with the function of the paper ejection roller. Instead of using a separate drive mechanism for the white reference member, the system combines both functions into a single drive source that controls the paper ejection roller, which in turn is mechanically linked to rotate the white reference member. This merging of functions eliminates the need for an additional independent drive source
2Device complexity
If the white reference member is rotated using the paper ejection roller drive source, then the number of drive sources is reduced, but the document may be pulled back into the conveying path during rotation
Solution Approach 1:
The patent applies the preliminary action principle by controlling the timing and sequence of operations: the white reference member is rotated for shading correction only when no document is present in the ejection path, and document ejection is performed only after the white reference member has been positioned correctly. The control unit manages the sequence to ensure that these two operations using the same drive source do not occur simultaneously, preventing documents from being pulled back into the conveying path
Solution Approach 2:
The patent implements dynamic control of the drive source by selectively engaging or disengaging the transmission mechanism between the drive source and the white reference member based on operational requirements. During document ejection, the transmission is disengaged to prevent unintended rotation. During shading correction, the transmission is engaged to allow rotation. This dynamic control ensures reliable document ejection while maintaining the ability to perform shading correction with the same drive source
Data Source
AI summary
A document conveying and reading device includes a drive motor, a paper ejection roller driven by the drive motor, a first reading unit arranged along a document conveying path to face one surface of the document, and a shading roller arranged along the document conveying path to face the first reading unit. The shading roller includes a white reference member used for shading correction and a conveying guide for a document that is conveyed along the document conveying path, is driven by the drive motor together with the paper ejection roller when the drive motor drives the paper ejection roller to rotate in the second direction, and is not driven by the drive motor together with the paper ejection roller when the drive motor drives the paper ejection roller to rotate in the first direction.