Reading Apparatus Roller Phase Correction for Image Distortion
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Solution Overview
Problem
Reading apparatuses face distortion in read images due to diameter errors and eccentricity in conveyance rollers, which affect the consistent conveyance amount per unit pulse cycle, making it difficult to change reading resolution effectively.
Innovation Solution
A reading apparatus with a conveyance roller, a detection unit to track the rotation phase, and a timing control circuit that uses index values to correct the conveyance amount per unit rotation angle, allowing for dynamic adjustment of reading timing based on detected errors to maintain desired resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If reading resolution is changed by post processing such as image thinning processing or averaging processing, then reading resolution can be adjusted, but reading must be performed at fixed resolution and data of read image must be stored
Solution Approach 1:
The patent pre-calculates and stores correction values (conveyance amounts per unit rotation angle for each rotation phase) based on detected diameter errors and eccentricity of the conveyance roller. This preliminary correction data is then used during reading operations to adjust reading timing without requiring post-processing of captured images, thereby reducing the need to store multiple resolution versions of images while enabling flexible reading resolution changes.
2Measurement precision
If encoder detection is used to control reading timing, then reading timing can be controlled according to reading resolution, but diameter error and eccentricity of conveyance roller cause variation in conveyance amount per unit pulse cycle resulting in image distortion
Solution Approach 1:
The patent uses the encoder detection feedback to monitor the rotation phase of the conveyance roller and applies pre-calculated correction values based on detected diameter errors and eccentricity. The reading timing control circuit adjusts the reading timing by the correction value corresponding to the current rotation phase, creating a feedback loop that compensates for mechanical imperfections and eliminates image distortion while maintaining precise reading timing control.
Data Source
AI summary
A reading apparatus includes a conveyance roller configured to convey a medium, a reading unit configured to read an image of the medium conveyed by the conveyance roller, a detection unit configured to detect a rotation phase of the conveyance roller, a storage unit configured to store index values, each index value being associated with the rotation phase of the conveyance roller and corresponding to a conveyance amount of the conveyance roller per unit rotation angle, and a timing control circuit configured to select the index value based on a detection result of the detection unit and to control a reading timing of the reading unit based on a result of comparing a cumulative value of selected index values with a threshold corresponding to a reading resolution.