Automatic Document Feeder Shading Correction via Reversible Drive
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Solution Overview
Problem
Conventional automatic document feeding devices and image forming apparatuses face challenges in maintaining consistent image quality due to light source unevenness and sensor sensitivity variations, which are not adequately addressed by periodic shading correction methods.
Innovation Solution
An automatic document feeding device with a conveyance unit, image reading unit, color reference member, moving assembly, and drive source, where the drive source changes rotation direction to reverse rotate the moving assembly and color reference member to perform shading correction using a white reference face, ensuring accurate and stable image reading and forming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If periodic shading correction is executed using a fixed color reference member, then shading correction can be performed, but image quality deteriorates due to light source unevenness and sensor sensitivity variations
Solution Approach 1:
The color reference member is made movable relative to the image reading unit through a moving assembly. The system dynamically adjusts the relative position by rotating the color reference member to different angular positions (0°, 45°, 90°, 135°, etc.) around the image reading unit, allowing selection of optimal reading positions that avoid light source unevenness and sensor sensitivity variations.
Solution Approach 2:
Before executing shading correction, the system preliminarily determines the optimal reading position by evaluating light source distribution and sensor sensitivity at different angular positions. The color reference member is pre-positioned at the optimal angle calculated from preliminary measurements, ensuring accurate shading correction without requiring multiple trial readings.
2Adaptability or versatility
If a separate drive source is provided for the moving assembly, then the color reference member can be moved for shading correction, but device complexity increases
Solution Approach 1:
The conveyance unit's drive source is made multi-functional by adding a movement regulator mechanism. The same motor that drives the conveyance unit also drives the moving assembly through the movement regulator, allowing one drive source to perform both document conveyance and color reference member positioning functions, thereby reducing overall system complexity.
Solution Approach 2:
A movement regulator is introduced as an intermediary mechanism between the conveyance unit's drive source and the moving assembly. This regulator selectively transmits or blocks rotational force based on operational mode, enabling the single drive source to control both the conveyance unit and the moving assembly without requiring separate motors or complex control circuitry.
3Productivity
If the movement regulator is disposed in the rotation transmission route, then the moving assembly can be controlled to move only when necessary, but device complexity increases
Solution Approach 1:
The movement regulator enables periodic engagement and disengagement of the moving assembly based on operational needs. During normal document conveyance, the movement regulator blocks force transmission to the moving assembly. During shading correction operations, the movement regulator engages to transmit rotational force to position the color reference member, achieving selective activation without continuous operation.
4Measurement precision
If the color reference member is moved to optimal reading positions, then image quality improves, but the time required for shading correction increases
Solution Approach 1:
The system performs preliminary measurement of light source distribution and sensor sensitivity at different angular positions before executing shading correction. Based on these preliminary results, the optimal reading position is calculated and the color reference member is pre-positioned at that angle, eliminating the need for multiple trial readings during the actual shading correction process.
Solution Approach 2:
The movement regulator enables rapid positioning of the color reference member to the pre-calculated optimal angle by directly transmitting rotational force only when needed. The system skips unnecessary intermediate positioning steps and transitions directly to the optimal reading position, minimizing the time required for shading correction while maintaining high measurement precision.
Data Source
AI summary
An automatic document feeding device includes a conveyance unit, an image reading unit, a color reference member, a moving assembly, and a drive source. The drive source includes a rotation output shaft to drive the conveyance unit and the moving assembly. The drive source changes the rotation output shaft from a forward rotation direction to a reverse rotation direction to reversely rotate the rotation output shaft to a set reverse rotation angle set in advance, according to a condition of conveyance of the document. In a rotation transmission route from the rotation output shaft to the moving assembly, the movement regulator is disposed in a first reverse rotation drive region from when a rotation direction of the rotation output shaft is changed to the reverse rotation direction to when a rotation angle of the rotation output shaft after the change in the reverse rotation direction reaches the set reverse rotation angle.