Keypad Light Guide with Tree-Like Structure for Uniform Illumination

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Solution Overview

Problem

Conventional light guides for keypads suffer from non-uniform light distribution and weakened light intensity due to the reflective and transmissive functions of peripheral walls, leading to inconsistent brightness across keys, especially for those farther from the light source.

Innovation Solution

A light guide with a tree-like structure featuring through hole portions with non-curved contour portions, including light incident and reflecting faces, where light is refracted and reflected to ensure uniform illumination across all keys using a minimal number of light sources, with the light incident faces increasing in size and reflecting faces decreasing from the proximate end to the distal end.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If light is reflected by peripheral walls of multiple holes to reach distant holes, then light can reach holes farther from the LED, but the light intensity is weakened and distribution becomes non-uniform

Engineering Contradiction:

Improvelight intensity at distant holesVSAvoidlight energy loss through multiple reflections

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The light guide structure pre-positions light incident faces at strategic locations to intercept and redirect light before it reaches distant holes, ensuring adequate illumination without requiring multiple reflections that would diminish intensity

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The light guide is divided into multiple through-holes, each with segmented functional surfaces (light incident faces and peripheral wall portions), allowing independent optimization of light distribution to different key regions

Inventive Principle:

Principle #1Segmentation

2Device complexity

If peripheral walls serve both light admission and reflection functions, then structural simplicity is maintained, but light distribution uniformity deteriorates

Engineering Contradiction:

Improvestructural simplicity of light guideVSAvoiduniformity of light distribution

Core Design Contradiction:

Device complexityVSStability of the object's composition

Solution Approach 1:

Different portions of the peripheral walls are assigned different optical functions: some portions serve as light incident faces with specific angles for direct light entry, while other portions serve as reflective surfaces, creating local functional differentiation to achieve uniform overall distribution

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The peripheral wall portions serve multiple functions simultaneously - they define hole geometry, provide light reflection, and in combination with light incident faces, create a multi-functional optical structure that maintains simplicity while achieving uniform distribution

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Use of energy by moving object

If a small number of light sources are used, then energy consumption is reduced, but achieving uniform illumination across all keys becomes difficult

Engineering Contradiction:

Improveenergy consumption of light sourcesVSAvoiduniformity of light distribution across keys

Core Design Contradiction:

Use of energy by moving objectVSIllumination intensity

Solution Approach 1:

The light distribution problem is solved by adding angular/directional control through specifically angled light incident faces, transforming the distribution mechanism from relying on multiple light sources to relying on geometric light redirection

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The light incident faces act as intermediary elements between the light sources and the distant holes, redirecting light at specific angles to reach areas that would otherwise be difficult to illuminate, enabling uniform distribution with minimal light sources

Inventive Principle:

Principle #24Intermediary (Mediator)

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 design ensures uniform light distribution and intensity across all keys on the keypad, achieving consistent brightness without the need for excessive light sources, by optimizing the geometry of the light guide to direct and reflect light effectively.

Implementation Method 1

A portion of light incident on the non-curved contour portion is reflected to at least one other through hole portion

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

Light incident on the light incident face is refracted into the corresponding through hole portion

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS7543971B2Light guide for use in a keypad

Publication Date: 2009.06.09 LITE ON TECH CORP

AI summary

A light guide for a keypad includes a plurality of through hole portions adapted to correspond respectively to keys on the keypad. Each of the through hole portions is adapted to receive at least a part of the corresponding key, and to receive light incident thereinto from at least one light source. Each of selected ones of the through hole portions has a contour with a non-curved contour portion that includes a light incident face and a reflecting face forming an angle with the light incident face. Light incident on the reflecting face is reflected into at least one other through hole portion. The light guide can also be configured to have a tree-like structure.