CIS Scanner Roller Eccentricity Detection via Image Analysis
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Solution Overview
Problem
Large format sheet feed scanners using contact image sensors (CIS) face issues with image quality due to pressure roller misalignment and eccentricity, leading to horizontal periodic banding (HPB) caused by uneven pressure distribution, which affects image focus and intensity.
Innovation Solution
Implementing methods to detect pressure roller eccentricity by analyzing scanned images using edge detection, peak detection algorithms, or Fourier transforms to identify periodic variations matching the pressure roller circumference, allowing for notification of errors or automatic service calls when HPB is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If pressure rollers are used to hold the document against the sensor, then image coverage is improved, but image quality deteriorates due to uneven pressure distribution causing horizontal periodic banding
Solution Approach 1:
The patent replaces direct mechanical pressure application with a detection system that uses image analysis to identify pressure roller eccentricity. By analyzing horizontal periodic banding patterns in scanned images through algorithms like Fourier transforms, the system detects roller misalignment without requiring complex mechanical adjustment mechanisms, thus maintaining image coverage while improving image quality consistency.
2Ease of manufacture
If pressure rollers are not properly aligned, then device assembly is simplified, but image quality deteriorates due to periodic variations in pressure causing focus shifts and intensity changes
Solution Approach 1:
The patent implements a feedback mechanism where scanned images are analyzed to detect horizontal periodic banding patterns. The system uses algorithms (such as Fourier transforms) to identify the presence and characteristics of pressure roller eccentricity. This feedback information can then be used to adjust or alert operators about roller alignment issues, maintaining ease of assembly while ensuring image quality through continuous monitoring and correction.
3Ease of manufacture
If the roller is not perfectly cylindrical, then manufacturing is easier, but image quality deteriorates due to varying effective radius causing horizontal periodic banding
Solution Approach 1:
The patent enables the scanning system to self-diagnose roller eccentricity by analyzing the scanned images for horizontal periodic banding patterns. The system automatically detects variations in the effective radius of the roller through image analysis, eliminating the need for separate manual inspection processes. This self-service capability allows for easier roller manufacturing while maintaining precision through automated detection and feedback.
Data Source
AI summary
A method and apparatus for detecting roller eccentricity in a CIS scanner is disclosed. An image of a target is captured using the CIS scanner. The image of the target is analyzed for periodic horizontal banding. The period of the periodic horizontal banding is compared with the circumference of a pressure roller in the CIS scanner. When the period matches with the circumference of the pressure roller, an error is set.