Image Reader Shading Correction Without Black Reference Plate
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Solution Overview
Problem
Existing image readers face challenges in miniaturization and preparation time due to the need for a black reference plate and complex light source positioning for dark current correction, which affects image quality and efficiency.
Innovation Solution
An image reader system that uses a white reference member to acquire white and black reference data by adjusting light source intensity, allowing for shading correction without a black reference plate, enabling miniaturization and simplifying the preparation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a black reference plate is used for dark current correction, then image quality is improved, but device size increases and preparation time increases
Solution Approach 1:
The patent extracts the black reference plate from the system by realizing that dark current can be measured and corrected without it. The light source is turned off during dark current measurement, eliminating the need for the black reference plate entirely, thus reducing device size while maintaining image quality through alternative dark current correction methodology
Solution Approach 2:
The white reference plate is given multiple functions: it serves both as the white reference for shading correction and as the surface for measuring dark current when the light source is off. This multi-functionality eliminates the need for a separate black reference plate, reducing device complexity and size while maintaining correction accuracy
2Reliability
If a black reference plate is used for dark current correction, then image quality is improved, but preparation time increases
Solution Approach 1:
The patent merges the dark current measurement function with the white reference plate measurement. By turning off the light source and using the same white reference plate, the system combines what would traditionally require separate operations and components into a single integrated process, reducing preparation time while maintaining image quality
Solution Approach 2:
The black reference plate is extracted from the preparation sequence entirely. Dark current measurement is performed by turning off the light source with the white reference plate in place, eliminating the step of positioning and measuring with a black reference plate, thus reducing preparation time without compromising correction accuracy
3Measurement precision
If complex light source positioning is used for dark current correction, then measurement precision is improved, but device complexity increases
Solution Approach 1:
Instead of positioning the light source to illuminate a black reference plate for dark current measurement, the patent inverts the approach: the light source is turned off completely and the white reference plate is used. This inversion simplifies the positioning requirements while maintaining measurement precision through the same optical path and sensor configuration
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 enhances image quality by improving signal-to-noise ratio and allows for the miniaturization of the image reader while reducing preparation time, as it eliminates the need for a black reference plate and simplifies light source positioning.
Implementation Method 1
a sensor configured to receive reflected light from the intended object and convert the received light into an image signal
Data Source
AI summary
An image reader including a controller configured to acquire white reference data based on a signal output from a sensor that has received reflected light from a white reference member, by controlling a light source to emit light of a first quantity onto the white reference member, acquire black reference data based on a signal output from the sensor that has received reflected light from the white reference member, by controlling the light source to emit light of a second quantity lower than the first quantity onto the white reference member, acquire image data of a document sheet based on a signal output from the sensor that has received reflected light from the document sheet, by controlling the light source to emit light of the first quantity onto the document sheet, and correct the acquired image data with the acquired white reference data and the acquired black reference data.