Scanner Shading Correction Circuit
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Solution Overview
Problem
Existing scanner devices face challenges in effectively correcting shading irregularities caused by temperature changes, sensor sensitivity variations, and optical system irregularities, leading to inadequate image quality due to factors like impurities, internal circuit configurations, and light source inconsistencies.
Innovation Solution
A scanner device with a circuit configuration that includes a production-time white level waveform memory, dark level correcting circuit, low-pass filter, phase/amplitude synchronizing circuit, and multiplying circuits to extract and correct for broad change components and phase shifts in the image signal waveform, thereby isolating and removing shading factors such as temporal changes in light source and sensor sensitivity, and lens array phase shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple correction data for temperature changes are stored, then the influence of temperature change can be reduced, but various correction data for temperature change are not easily prepared and shading is not easily and sufficiently corrected
Solution Approach 1:
The patent changes the approach from storing multiple discrete correction data sets to dynamically calculating correction values based on temperature parameters. The system measures actual temperature and uses it to compute correction coefficients, transforming the problem from data management to parameter-based calculation.
Solution Approach 2:
The system performs self-correction by automatically measuring its own temperature and calculating the necessary correction values without external intervention. The scanner device uses its internal temperature sensor and processing capabilities to generate correction data in real-time, eliminating the need for pre-prepared correction data sets.
2Measurement precision
If dark level correction is performed by subtracting dark level waveform, then output level can be adjusted, but shading factors including temporal light source changes and sensor sensitivity changes are not fully addressed
Solution Approach 1:
The patent extends the correction function to handle multiple types of shading errors simultaneously. The correction coefficient calculation incorporates temperature compensation, temporal light source drift, and sensor sensitivity variations into a single unified correction mechanism, making the system versatile against various shading causes.
Solution Approach 2:
The system continuously monitors temperature and uses this feedback to dynamically adjust correction coefficients. By measuring actual operating conditions and feeding this information back into the correction calculation, the system adapts to changing conditions rather than relying on fixed correction values.
3Manufacturing precision
If white reference is used for correction, then white level irregularity can be corrected, but cycle patterns caused by lens array phase shifts are not removed
Solution Approach 1:
The patent separates the correction process into distinct components: one handling white level irregularity and another specifically targeting cycle patterns. By segmenting the correction coefficients into different functional parts, the system can address each type of distortion independently and more effectively.
Solution Approach 2:
The patent introduces temperature-based correction coefficients as an intermediary mechanism between the raw sensor data and the final corrected image. This intermediary layer processes both white level irregularities and cycle patterns through a unified mathematical transformation, eliminating multiple harmful factors simultaneously.
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
The solution enables precise shading correction by isolating and removing shading factors, resulting in improved image quality by normalizing the image signal waveform and reducing errors caused by white level irregularities and phase shifts, enhancing the accuracy of scanned images.
Implementation Method 1
an image sensor that reads an image of an original
Data Source
AI summary
A shading correction of removing a plurality of shading factors is performed. A scanner device performs a shading correction in a manner such that a low-pass filter circuit (14) extracts a broad waveform change component caused by a temperature characteristic and a temporal change in light source or sensor sensitivity as shading factors, a phase/amplitude synchronizing circuit (15) extracts a phase shift of a cycle pattern of a lens array, a first multiplying circuit (16) synthesizes the waveforms of the extracted factors so as to form a correction-purpose image signal waveform, and the correction-purpose image signal waveform is divided from an image signal waveform subjected to a dark level correction (offset).