Bar Light Guide with Elliptical Output Surfaces for Uniform Illumination
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Solution Overview
Problem
Conventional light guides have inefficiencies in utilizing light, particularly in image reading apparatuses, where light distribution is not optimized, leading to suboptimal illumination and increased costs due to multiple reflective surfaces.
Innovation Solution
A light guide with a bar-like shape featuring a reflective surface and elliptical output surfaces, where light enters and exits through focal points, enhancing light use efficiency by converging light at specific focal points within the guide, and utilizing a single reflective surface for two output surfaces to reduce production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple reflective surfaces are used in conventional light guides, then light distribution can be improved, but production costs increase
Solution Approach 1:
The patent merges the functions of multiple reflective surfaces into a single reflective surface that is shared between two output surfaces. This single reflective surface is positioned to reflect light toward both the first output surface and the second output surface, thereby achieving improved light distribution without the need for multiple separate reflective surfaces, which reduces production costs.
Solution Approach 2:
The single reflective surface is designed to serve multiple functions simultaneously: it reflects light toward the first output surface and also reflects light toward the second output surface. This multi-functional design allows the light guide to achieve uniform illumination across both output surfaces while using fewer components, thereby reducing manufacturing complexity and cost.
2Ease of manufacture
If conventional light guide structures are used, then manufacturing is simpler, but light use efficiency is reduced
Solution Approach 1:
The patent applies different geometric characteristics to different parts of the light guide: the output surfaces are designed with specific curved shapes (first output surface with first curvature, second output surface with second curvature) while the reflective surface has a specific positioning relative to these curved surfaces. This local optimization of geometric quality allows light to be efficiently directed and distributed, improving light use efficiency while maintaining reasonable manufacturing simplicity.
Solution Approach 2:
The patent employs curved surfaces instead of flat surfaces in the light guide structure. The first output surface and second output surface are designed with curved geometries that work in conjunction with the reflective surface to efficiently direct and distribute light. This curvature-based design improves light use efficiency by enabling better light control and distribution compared to conventional flat-surfaced light guides.
3Device complexity
If light is not converged at focal points, then the light guide structure is simpler, but illuminance distribution becomes non-uniform
Solution Approach 1:
The reflective surface is pre-positioned at a specific location relative to the output surfaces, designed to receive light and reflect it toward the output surfaces in a controlled manner. This preliminary positioning of the reflective surface ensures that light is converged at appropriate focal points before reaching the output surfaces, resulting in uniform illuminance distribution without requiring complex additional optical elements.
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 light guide achieves improved light use efficiency by converging light at precise focal points, ensuring uniform illuminance distribution and reducing production costs by sharing a reflective surface for multiple output surfaces.
Implementation Method 1
a reflective surface that reflects light inside the light guide within the light guide
Implementation Method 2
the first output surface, when viewed in plan from the predetermined direction, constituting a first arc of an ellipse that has a first focal point, along with a second focal point located on the reflective surface
Data Source
AI summary
A light guide with a bar-like shape that extends in a predetermined direction, having: a reflective surface that reflects light inside the light guide within the light guide; a first output surface that causes light inside the light guide to exit the light guide, the first output surface, when viewed in plan from the predetermined direction, constituting a first are of an ellipse that has a first focal point, along with a second focal point located on the reflective surface, and the first are being closer to the first focal point than to the second focal point; and a second output surface that causes light inside the light guide to exit the light guide, the second output surface, when viewed in plan from the predetermined direction, constituting a second arc of an ellipse that has a third focal point, along with a fourth focal point coinciding with the second focal point, and the second arc being closer to the third focal point than to the fourth focal point.