Arc-Light Guide Illumination Device Uniform Intensity
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Solution Overview
Problem
The existing illumination devices for image reading devices face challenges in maintaining uniform light intensity distribution, particularly when using multiple light sources, due to complex light guide shapes and difficulty in setting precise positions of light sources, leading to variations in light intensity and illumination spots in the read images.
Innovation Solution
The illumination device features a light guide with an arc-like exit surface and a diffuse reflecting surface, where the light sources are positioned on a circuit board aligned with the optical axis, allowing for easy adjustment and maintaining a predetermined gap to ensure uniform light intensity distribution, with the light guide and circuit board sharing a common reference surface for precise alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple light sources are used to increase light intensity, then the overall light intensity is improved, but the light intensity distribution becomes non-uniform and illumination spots occur
Solution Approach 1:
The light guide exit surface is formed into an arc-like shape with a radius of curvature R, creating a curved emitting surface. This curvature is specifically designed so that light sources positioned at different locations on the arc can achieve uniform light intensity distribution across the reading area, eliminating illumination spots while maintaining high overall intensity through multiple light sources
2Manufacturing precision
If the light guide shape is made complex to control light distribution, then the light intensity distribution is improved, but the difficulty of setting light source positions increases
Solution Approach 1:
Instead of using a complex multi-faceted or irregular light guide shape, the invention employs a simple arc-like curved surface. This curved geometry provides sufficient control over light distribution through its mathematical properties (radius of curvature R) while being much easier to manufacture and align with light sources compared to complex polyhedral or irregular shapes
3Use of energy by moving object
If the gap between light source and light guide is reduced to increase light coupling efficiency, then the light coupling efficiency is improved, but the alignment precision requirement increases
Solution Approach 1:
The arc-like exit surface with radius of curvature R creates an optical geometry where light sources can be positioned at specific locations while maintaining optimal coupling. The curved surface acts as a natural optical element that tolerates small gaps between light sources and light guide, reducing the stringency of alignment requirements compared to flat surface configurations
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 achieves higher light intensity at the ends than at the center, optimizing light intensity distribution for optical reduction systems, increasing image reading speed, and reducing illumination spots by facilitating precise assembly and maintaining a stable light intensity profile.
Implementation Method 1
a light guide that diffuses light from the light source uniformly in the main scan direction
Implementation Method 2
a diffuse reflecting surface for diffusing and reflecting the light taken in from the end face
Data Source
AI summary
To provide an illumination device in which there is no variation in light intensity distribution of the illumination device, and in which illumination spots, particularly light intensity spots, are not prone to occur in a read image in an image reading device, by maintaining a constant gap between a light source and an end face of a light guide. The illumination device includes: a light guide having an end face for taking in light, a diffuse reflecting surface for diffusely reflecting the light taken in from the end face, and a light exit surface for emitting the light that is diffusely reflected at the diffuse reflecting surface towards an irradiation surface. The illumination device further include a reflector having a diffuse reflecting surface that reflects light from the light source toward the one end face of the light guide. The light guide has, at the one end, a flange portion that abuts the reflector, the light source is mounted to a circuit board, and the reflector is held between the flange portion of the light guide and circuit board so as to maintain a predetermined gap between the light source and light guide.