Light Guide Gate Positioning for Uniform Illumination
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Solution Overview
Problem
Existing illumination apparatuses with light guides made of resin materials, such as acrylic resin, face issues with uneven luminance distribution due to projections and recesses from the gate-cut surface during injection molding, which can lead to increased production costs and reduced optical stability when trying to increase light quantity by placing light sources at opposite ends.
Innovation Solution
A configuration where the gate portion for injection molding is positioned at the tip face of a positioning portion on the light guide, allowing the light guide to be formed without gate-cut surfaces at the light incident ends, thus preventing uneven luminance distribution and reducing the need for costly smoothing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light sources are provided at opposite ends of a light guide to increase light quantity, then illumination intensity is improved, but uneven luminance distribution occurs due to projections and recesses from gate-cutting
Solution Approach 1:
The light guide is divided into functional sections: a positioning portion at one end that receives the gate-cut, and light incident surfaces at both ends for illumination. This segmentation isolates the gate-cut area from the optical path, allowing rough cutting at the positioning portion while maintaining smooth, uniform light incident surfaces at the illumination ends.
Solution Approach 2:
The gate portion is extracted and relocated to the positioning portion at one end of the light guide, separate from the light incident surfaces. This extraction removes the source of projections and recesses from the critical optical areas, eliminating the cause of uneven luminance distribution while preserving the dual-end illumination capability.
2Ease of manufacture
If gate portion is provided at the other end face for injection molding, then manufacturing is simplified, but projections and recesses cause increased production costs due to required smoothing processes
Solution Approach 1:
Different parts of the light guide are assigned different surface quality requirements: the positioning portion at one end accepts rough gate-cut surfaces, while the light incident surfaces at both ends maintain smooth finishes. This local quality differentiation eliminates the need for costly smoothing processes on the gate-cut area, as the rough surface is isolated from the optical path.
3Reliability
If gate portion is positioned away from light emission area, then optical stability is improved, but positioning accuracy decreases due to lack of reference feature
Solution Approach 1:
The positioning portion serves dual functions: it provides a location for the gate-cut (maintaining optical stability by separating it from light incident surfaces) and simultaneously acts as a positioning reference feature for assembling the light guide with other components. This merging of functions eliminates the need for separate reference features while maintaining both optical stability and positioning accuracy.
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 ensures uniform luminance distribution and stable optical properties by minimizing unintended diffused or leak light, allowing for increased light quantity without compromising positioning accuracy or increasing production costs.
Implementation Method 1
A light guide that is formed in a rod shape, and that includes a positioning portion that is formed at one end in a longitudinal direction, and light incident surfaces that are formed at two end faces in the longitudinal direction
Data Source
AI summary
An illumination apparatus includes: a light guide that is formed in a rod shape and includes a positioning portion that is formed at one end in a longitudinal direction, and light incident surfaces that are formed at two end faces in the longitudinal direction; and light sources that are arranged in the vicinity of the light incident surfaces, respectively, and that emit light that is incident on the incident surfaces. The light guide is formed by injection molding. A gate portion for supplying a resin material during injection molding opens at a position that corresponds to a tip face of the positioning portion.