Ring-Shaped Touch Panel Light Guide for Uniform Switch Illumination
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Solution Overview
Problem
Conventional illumination methods for large, ring-shaped touch switches face challenges in achieving uniform brightness with a minimal number of light sources, leading to increased costs and potential air gaps that interfere with capacitance detection.
Innovation Solution
A light guide element with a diffusion surface of varying width, positioned between light sources, ensures even illumination of a ring-shaped touch switch by diffusing light emitted from multiple sources, reducing brightness unevenness and preventing air gaps between the touch panel and electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple light sources are provided around the light guide element to illuminate large ring-shaped touch switches, then illumination intensity and visibility are improved, but device complexity and manufacturing costs increase
Solution Approach 1:
Multiple light sources are merged into a single light guide element that distributes light uniformly across the ring-shaped touch switch. The light guide element integrates the function of multiple light sources into one component, reducing device complexity while maintaining high illumination intensity through internal light distribution.
Solution Approach 2:
The light guide element acts as an intermediary between the light source and the touch switch. It receives light from a single source and redistributes it uniformly across the entire ring-shaped area, achieving the effect of multiple light sources without the complexity of installing multiple separate sources.
2Illumination intensity
If a reflection surface is provided in a limited area to concentrate light, then illumination intensity at specific points is improved, but uniformity of illumination across large areas deteriorates
Solution Approach 1:
The light guide element incorporates local variations in its structure (such as varying thickness or refractive index in different regions) to optimize light distribution. This allows different parts of the light guide to perform different functions - some regions concentrate light while others distribute it - achieving both high intensity and uniformity simultaneously.
3Illumination intensity
If the distance from light source to touch switch is reduced to increase illumination intensity, then visibility is improved, but capacitance detection accuracy deteriorates due to air gap interference
Solution Approach 1:
The light guide element serves as an intermediary structure that simultaneously addresses illumination and capacitance detection requirements. It provides optical coupling between the light source and touch switch while maintaining electrical coupling, eliminating air gaps that would interfere with capacitance sensing while still achieving high illumination intensity.
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 allows for uniform and intense illumination of large ring-shaped touch switches with a minimal number of light sources, enhancing visibility and maintaining reliable capacitance detection without increasing manufacturing costs.
Implementation Method 1
The light guide element has a diffusion surface having a ring-like shape formed on a second surface. Light emitted from the light source and incident to the light guide element is diffusion-reflected on the diffusion surface
Data Source
AI summary
A touch panel includes a ring-like shaped light-transmissive portion. A ring-shaped diffusion surface is formed on the bottom surface of a light guide element. The ring-like shape includes a second region provided at a location corresponding to two light sources adjacent to a first region corresponding to one light source. A distance from a location of the ring-shaped light-transmissive portion to a periphery of the ring close to the light source is greater in the second region than in the first region. Light emitted from the light source and incident to the light guide element is diffusion-reflected on the diffusion surface and a part of the diffusion-reflected light illuminates the light-transmissive portion.