Background Reflection Section for Document Reading Edge Detection
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Solution Overview
Problem
Document reading devices face issues with image blurring at document edges due to uneven light source brightness, causing incorrect luminance detection and subsequent image defects, particularly when the background-reflected light exceeds the document-reflected light in intensity.
Innovation Solution
A background reflection section is designed to reflect less light than a specular surface and more than document-reflected light, ensuring a sufficient difference for accurate edge detection, formed by processing a specular surface to reduce specular reflection and diffuse incident light, thereby preventing saturation in image sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a specular surface is used for the background reflection section, then the amount of reflected light is increased, but image blurring occurs at document edges due to saturation of image sensors
Solution Approach 1:
The patent changes the reflection characteristics of the background reflection section by processing the specular surface to create a diffuse reflection surface. This parameter change reduces the reflected light intensity to a level that prevents sensor saturation while maintaining sufficient luminance difference for accurate edge detection. The processing transforms the surface from highly reflective (specular) to moderately reflective (diffuse), resolving the contradiction between needing enough light for detection and avoiding excessive light that causes blurring.
2Measurement precision
If the background-reflected light intensity is increased to improve edge detection, then the luminance difference becomes insufficient, causing signal charge overflow and diffusion in image sensors
Solution Approach 1:
The patent converts the potentially harmful effect of high background light intensity (which causes sensor saturation and charge diffusion) into a beneficial outcome by controlling it to an optimal level. The processed surface provides just enough reflected light to maintain visible luminance difference for edge detection, while preventing the excessive intensity that would cause charge overflow. This transforms the harmful saturation effect into a beneficial balanced state where detection accuracy is maintained without sensor damage.
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 configuration effectively suppresses image blurring by maintaining a balanced luminance difference between background and document-reflected light, enhancing detection accuracy and image quality by preventing overflow and diffusion of signal charges in image sensors.
Implementation Method 1
a background reflection section disposed to reflect the light from the light source so as to be received by the light receiving section through the reading position
Implementation Method 2
the background reflection section is formed by processing a specular surface so as to reflect an amount of light that is less than an amount of specularly reflected light reflected by a specular surface
Data Source
AI summary
A document reading device includes: a reading position at which information on a document is read; a light source that radiates light toward the document passing through the reading position; a light receiving section that receives reflected light generated from the light from the light source; and a background reflection section disposed to reflect the light from the light source so as to be received by the light receiving section through the reading position. When the document is not present, the background reflection section reflects an amount of light that is greater than an amount of document-reflected light reflected by the document which is white. The background reflection section is formed by processing a specular surface so as to reflect an amount of light that is less than an amount of specularly reflected light reflected by a specular surface.