Light Guide Optical System for Uniform Document Illumination
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Solution Overview
Problem
Document illuminating devices using point light sources suffer from non-uniform illuminance in the main scanning direction, leading to inconsistent image quality due to random light diffusion and flare phenomena, which reduces light use efficiency and image quality.
Innovation Solution
A light guide optical system with a plurality of point light sources and periodically arranged curved reflecting surfaces that guide light beams to the document surface, ensuring uniform illuminance without increased diffusion outside the illuminated region, using a light guide optical system with an entrance and exit surface and convex curved surfaces to converge light beams in the main scanning direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light diffusing portion is used to eliminate non-uniformity of illuminance, then illuminance uniformity is improved, but light use efficiency deteriorates due to random diffusion toward outside the illuminated region and absorption reflection phenomenon
Solution Approach 1:
The patent applies curved reflecting surfaces with specific radius of curvature to redirect light beams. The curved surfaces reflect light in a controlled manner to achieve uniform illuminance distribution across the illuminated region while containing the light within the desired area, thereby maintaining high light use efficiency without random diffusion or absorption reflection losses.
2Area of stationary object
If the illuminating angle is increased to illuminate a broader range, then illuminance coverage is improved, but absorption reflection phenomenon increases causing further loss of light use efficiency
Solution Approach 1:
The curved reflecting surfaces are designed with specific geometric parameters to achieve the desired illuminating angle while maintaining efficient light reflection. The curvature allows light to be directed over a broader area through controlled reflection angles, expanding the illuminated range without causing absorption reflection phenomenon that would reduce light use efficiency.
3Ease of manufacture
If point light sources are arranged linearly to reduce cost, then device cost is reduced, but illuminance uniformity deteriorates due to non-uniform illuminance in the main scanning direction
Solution Approach 1:
The curved reflecting surfaces compensate for the non-uniform light distribution from linearly arranged point light sources. By strategically designing the curvature and positioning of these surfaces, the system redistributes light intensity across the illuminated region to achieve uniform illuminance, thereby maintaining cost-effectiveness with simple point light sources while eliminating illuminance non-uniformity.
4Illumination intensity
If light beams are diffused randomly to uniformize illuminance, then illuminance uniformity is improved, but flare phenomenon occurs degrading image reading quality
Solution Approach 1:
The curved reflecting surfaces provide controlled, directional reflection of light beams rather than random diffusion. This controlled reflection achieves uniform illuminance distribution across the document surface while directing light precisely within the intended illuminated region, thereby eliminating flare phenomenon that would otherwise occur with random light diffusion and degrade image reading quality.
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 achieves uniform illuminance across the document surface, enhancing image quality and light use efficiency while maintaining low costs and reducing flare phenomena, allowing for effective image reading without the need for extensive image correction.
Implementation Method 1
a plurality of curved reflecting surfaces that reflect the plurality of light beams having passed through the entrance surface
Data Source
AI summary
A light guide optical system guides a plurality of light beams emitted from a plurality of point light sources arranged linearly to a predetermined surface. The light guide optical system has a plurality of optical surfaces arranged periodically in the arrangement direction of the plurality of point light sources. Each of the plurality of optical surfaces has power in the arrangement direction of the plurality of point light sources.