Calibration Strip Geometry for Scanner Optical Module Alignment
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Solution Overview
Problem
Calibration of document scanning systems is challenging due to variations in illumination intensity and sensor changes over time, particularly in determining the optimal calibration position on calibration strips, especially for internal second-side scanners.
Innovation Solution
The method involves using imaging sensors to obtain an image scan of a calibration strip with specific geometric configurations, such as vertical and sloping horizontal lines, to calibrate the optical module, optimizing the calibration position and speed measurements to ensure consistent imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a calibration strip is used to compensate for illumination intensity changes and sensor changes, then imaging consistency over time is improved, but determining the optimal calibration position becomes difficult and complex
Solution Approach 1:
The calibration strip uses distinct color patterns (e.g., alternating black and white lines, or specific color sequences) that create high-contrast visual signals. The imaging sensor detects these color variations to automatically determine the calibration position and measure strip width, eliminating the need for manual position selection and reducing determination complexity.
Solution Approach 2:
The calibration strip contains a predefined geometric pattern (such as lines at specific distances from edges, or a known slope configuration) that serves as a reference copy. The system captures an image of this pattern and uses image processing to identify features like line positions, distances, and slopes, thereby automatically determining calibration parameters without manual measurement.
2Measurement precision
If the calibration strip has specific geometric configurations (vertical lines, sloping horizontal lines), then calibration position and speed measurements are optimized, but the design and manufacturing of the calibration strip becomes more complex
Solution Approach 1:
The calibration strip is divided into distinct geometric segments: vertical lines positioned at specific distances from edges, and a sloping horizontal line connecting them. Each segment serves a specific measurement function (vertical lines for position reference, sloping line for speed and orientation calibration), making the overall complex pattern easier to manufacture by treating it as an assembly of simple, standardized elements.
Solution Approach 2:
The calibration strip uses variable geometric parameters (distances of vertical lines from edges, slope of horizontal line) that can be adjusted based on specific calibration requirements. By changing these parameters rather than redesigning the entire strip structure, the system achieves optimized measurement precision while maintaining ease of manufacturing through parameter adjustment rather than structural complexity.
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 compensates for illumination and sensor differences, ensuring consistent imaging performance over time by accurately determining the calibration position and speed, thereby reducing calibration artifacts and identifying potential photoreceptor malfunctions.
Implementation Method 1
use imaging sensors of an optical module of a document scanning device to obtain an image scan of a calibration strip
Data Source
AI summary
What is disclosed is an apparatus and method for calibrating an optical module of a document scanning device. In one embodiment, imaging sensors of an optical module of the scanning device are used to obtain an image scan of a calibration strip mounted on a surface of a platen on which a sheet to be scanned has been manually placed. The calibration strip has a first vertical line at a first distance from a right edge of the strip, a second vertical line at a second distance from a left edge of the strip, and a sloping horizontal line positioned between the first and second vertical lines. A slope of the horizontal line is non-zero. In a manner more fully disclosed herein, the image scan of the calibration strip is to obtain calibration measurements. The calibration measurements are, in turn, used to calibrate the scan head of the optical module.