Rod-Shaped Light Guide with Asymmetric Diffuser for Uniform Illumination
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Solution Overview
Problem
The existing light guiding systems in scanner devices suffer from non-uniform illuminance distribution in the sub-scanning direction due to varying light reflection frequencies along the light guiding member, leading to increased light loss and inefficiency.
Innovation Solution
A rod-shaped light guiding member with a belt-like diffusing portion and a reflective portion, where the diffusing portion is narrower than the reflective portion, is used to control light distribution, reducing non-uniformity and light loss by strategically diffusing light emitted from the output surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a diffusing member is provided on the entire output surface of the light guiding member, then the degree of non-uniformity in light distribution is reduced, but light loss increases due to unnecessary diffusion of light that already has a wide range of distribution
Solution Approach 1:
The output surface is divided into two distinct regions: a diffusing portion with a diffusing member that diffuses light, and a non-diffusing portion without a diffusing member that allows light to pass through without diffusion. This local differentiation ensures that only light requiring diffusion (light with narrow distribution range) is diffused, while light that already has wide distribution range passes through unchanged, thereby reducing unnecessary light loss while maintaining uniformity.
2Illumination intensity
If the diffusing portion width is increased to cover more of the output surface, then more light is diffused to reduce non-uniformity, but more light is unnecessarily diffused causing increased light loss
Solution Approach 1:
The width of the diffusing portion is carefully controlled to be less than the full width of the output surface. This parameter optimization ensures that the diffusing portion covers only the region where light diffusion is beneficial (near the LED where light has narrow distribution range), while excluding regions where light already has wide distribution range, thus preventing unnecessary light loss.
3Loss of energy
If the light guiding member is designed to guide light efficiently with minimal reflections, then light loss is reduced, but light distribution uniformity deteriorates due to variation in reflection frequency along the member
Solution Approach 1:
The light guiding member is designed with different surface properties at different locations: the output surface includes a diffusing portion with a diffusing member to diffuse light and improve uniformity, while the counter surface includes a reflective portion to reflect light toward the output surface. This local differentiation allows the member to simultaneously reduce light loss through efficient guidance while achieving uniform light distribution through targeted diffusion and reflection.
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 reduces the degree of non-uniformity in light distribution in the sub-scanning direction while minimizing light loss, resulting in more uniform illuminance and improved efficiency.
Implementation Method 1
The output surface has a belt-like diffusing portion extending in the longitudinal direction, the diffusing portion being configured to diffuse light emitted from the output surface
Implementation Method 2
The counter surface has a belt-like reflective portion extending in the longitudinal direction, the reflective portion being configured to reflect light toward the output surface
Implementation Method 3
light guided into the light guiding member propagates inside the light guiding member while being totally reflected by the inner surface of the light guiding member in accordance with Snell's law
Data Source
AI summary
A light guiding member includes an input surface, an output surface, a counter surface, a reflective portion, and a diffusing portion. The light guiding member is a rod-shaped member that guides light in a longitudinal direction thereof. The input surface is one end face of the light guiding member and allows light to be input thereon. The output surface has a belt-like shape, extends in the longitudinal direction, and allows light to be emitted therefrom. The counter surface is located opposite the output surface. The reflective portion is a belt-like portion extending in the longitudinal direction and reflects light toward the output surface. The diffusing portion is a belt-like portion extending in the longitudinal direction and diffuses light emitted from the output surface. The diffusing portion is smaller than the reflective portion in width in a direction orthogonal to the longitudinal direction.