Image Reading Apparatus Skew Correction Resolution
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Solution Overview
Problem
Image reading apparatuses face challenges in accurately correcting document skew due to variations in nip pressure and rotation speed, leading to image degradation, especially when the main-scanning and sub-scanning resolutions differ, resulting in incorrect skew angle determination and increased image degradation with larger correction angles.
Innovation Solution
The apparatus includes a stacking unit, conveying unit, regulating unit, and reading unit with a processor that adjusts reading resolutions based on document length to minimize skew correction, setting higher sub-scanning resolution when the document is short and lower when it is long, to reduce image degradation and ensure accurate skew correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If rotational correction is applied to correct document skew, then the inclination of the image is corrected, but steps appear in lines and image degradation increases with larger correction angles
Solution Approach 1:
The patent changes the reading resolution parameters (main-scanning resolution and sub-scanning resolution) based on document length to control the skew angle magnitude. For longer documents, it uses lower sub-scanning resolution (300 dpi) to reduce skew angle, while for shorter documents, it uses higher resolution (600 dpi) to maintain image quality when larger correction angles are acceptable
Solution Approach 2:
The patent dynamically adjusts the reading resolution settings based on the detected document length. The controller selects different resolution combinations (600×600 dpi or 300×600 dpi) according to whether the document is long or short, making the system adaptive to different document types to optimize both skew correction accuracy and image quality
2Manufacturing precision
If higher reading resolution is used to maintain image quality, then image detail is preserved, but skew angle determination becomes incorrect when main-scanning and sub-scanning resolutions differ
Solution Approach 1:
The patent uses different resolution parameter combinations (600×600 dpi or 300×600 dpi) depending on document length. By selecting appropriate resolution settings, it ensures that skew angle determination remains accurate while maintaining sufficient image quality for the given document size
3Manufacturing precision
If sub-scanning resolution is increased for short documents to maintain image quality, then image detail is preserved, but skew correction angle increases causing more image degradation
Solution Approach 1:
The patent adjusts sub-scanning resolution based on document length: using 300 dpi for long documents to minimize skew angle and image degradation, and 600 dpi for short documents where larger correction angles are tolerable and higher resolution is needed to preserve image quality
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
This approach effectively reduces image degradation and ensures accurate skew correction by dynamically adjusting reading resolutions, maintaining image quality across varying document lengths and resolutions.
Implementation Method 1
a reading unit configured to read an image of the document conveyed by the conveying unit, the reading unit including a light-receiving element configured to receive light
Data Source
AI summary
An image reading apparatus includes: at least one processor configured to: set reading resolutions in a first and a second directions when reading an image of a document; determine an inclination amount of the document; correct an image to reduce the inclination amount; output image data indicative of an corrected image; and obtain information relating to a first direction length of the document. In a case where the first direction length of the document is less than a predetermined length and the processor outputs the image data indicative of the corrected image, whose resolution in the first direction is a first resolution and resolution in the second direction is a second resolution lower than the first resolution, the processor sets the reading resolution in the second direction to a third resolution higher than the second resolution.