Input Device Light Guide Penetration Hole Luminance Control
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Solution Overview
Problem
Conventional touch switch devices with light guide plates suffer from luminance unevenness due to increased optical path lengths and varying distances from light emitters to design portions, leading to inconsistent brightness across the input device.
Innovation Solution
The input device incorporates a substrate with a detection electrode, a light emitter on the back surface, a body plate for light transmission, and a light guide with an incident and exit surface, where the light guide is positioned in a penetration hole to minimize optical path length and ensure consistent light distribution, using reflective surfaces to enhance brightness and clarity of the design pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light guide plate with extending portion is used to guide light from the light emitter, then the light can be transmitted to the design portion, but the optical path length increases causing luminance unevenness
Solution Approach 1:
The light guide is divided into two distinct portions: a first light guide portion with a light guide function and a second light guide portion with a design pattern. This segmentation allows the light to be guided efficiently while the design portion can be optimized for uniform light emission, resolving the luminance unevenness caused by the extending portion in conventional designs.
Solution Approach 2:
A reflection member is introduced as an intermediary element positioned between the light emitter and the light guide. This reflection member redirects light into the light guide more efficiently, shortening the effective optical path length and reducing luminance unevenness while maintaining proper light transmission to the design portion.
2Illumination intensity
If the light guide extends from the light guide plate main body to guide light, then light emission is achieved, but the device thickness increases
Solution Approach 1:
The light guide is integrated directly with the design portion, merging the light guiding function and the design display function into a single component. This eliminates the need for a separate extending portion that would increase device thickness, while still achieving effective light guidance and emission.
Solution Approach 2:
The light guide structure is redesigned to utilize the planar dimension more effectively rather than extending in the thickness dimension. By optimizing the light guide layout within the plane of the design portion and using reflective surfaces, the patent achieves proper light guidance without increasing device thickness.
3Illumination intensity
If multiple components (light guide plate, extending portion, design portion) are used, then light guidance and design display are achieved, but the device complexity increases
Solution Approach 1:
The patent merges the light guide and design portion into a single integrated component, reducing the total number of parts. The design portion serves dual functions: displaying the design pattern and guiding light, thereby simplifying the overall structure while maintaining effective light guidance and display capabilities.
Solution Approach 2:
The design portion is given multiple functions: it serves as both the visual design element and the light guide structure. This multi-functionality eliminates the need for separate dedicated light guide components, reducing device complexity while achieving both light guidance and design display objectives.
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 suppresses luminance unevenness, ensures reliable touch detection, and maintains a thin structure by minimizing wiring and protrusions, while allowing for easy manufacturing through multicolor molding and insert molding processes.
Implementation Method 1
a light guide with an incident surface from which light emitted by the light emitter enters and a light exit surface from which the light entered from the incident surface exits
Implementation Method 2
using reflective surfaces to enhance brightness and clarity of the design pattern
Data Source
AI summary
An input device includes: a substrate; a first detection electrode that detects input to the input device; a light emitter that emits light when the input is performed; a body plate disposed on the front surface side of the substrate and through which the light is transmitted; and a light guide including an incident surface from which the light enters and a light exit surface from which the light entered from the incident surface exits. A design portion that is light transmissive is disposed on an opposite side of the body plate to the substrate. A penetration hole penetrates through the substrate at a position opposite the design portion. The light guide is disposed in the penetration hole with the incident surface oriented facing a light emitting surface of the light emitter and the light exit surface oriented facing the design portion with the body plate interposed therebetween.