Keyboard Light Guide Structure for Uniform Key Illumination

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Solution Overview

Problem

Existing keyboard illumination systems often suffer from non-uniform light distribution and inefficiencies in light transmission due to the limited location, orientation, and size of light-emitting diodes (LEDs) behind keycaps, which affects the quality and quantity of light visible to users in dimly-lit environments.

Innovation Solution

The proposed solution involves a keyboard design with a light guide system that includes a compressible dome, a keycap, and a light-emitting element optically coupled to a light guide with internal features such as reflection and illumination features, which direct and reflect light internally to provide uniform illumination across the keycap, reducing light leakage and enhancing the visibility of key glyphs and surrounding areas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a light-emitting diode (LED) is disposed behind a keycap to illuminate the key, then the key becomes visible in dimly-lit environments, but the location, orientation, and size of the LED are limited by the key structure, resulting in non-uniform light distribution

Engineering Contradiction:
Improvelight visibilityVSAvoidlight distribution uniformity
Core Design Contradiction:
Illumination intensityVSEase of operation

Solution Approach 1:

The patent introduces a light guide plate as an intermediary component between the LED light source and the keycap. The light guide plate receives light from the LED and redistributes it uniformly across the keycap surface through its optical properties, solving the problem of non-uniform light distribution caused by limited LED placement options

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent extracts the light distribution function from the LED itself and transfers it to a dedicated light guide plate component. This separation allows the LED to focus on light generation while the light guide plate handles light distribution, resolving the contradiction between visibility and uniformity

Inventive Principle:
Principle #2Taking out (Extraction)

2Illumination intensity

If the LED is positioned to maximize light output, then illumination intensity increases, but light leakage occurs and surrounding areas are not properly illuminated

Engineering Contradiction:
Improvelight outputVSAvoidlight leakage
Core Design Contradiction:
Illumination intensityVSObject-generated harmful factors

Solution Approach 1:

The light guide plate acts as a mediator that controls and directs light flow. It has optical features that guide light toward the keycap while preventing lateral leakage, thus maintaining high illumination intensity without the harmful effect of light leakage to surrounding areas

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The light guide plate incorporates localized optical features at specific positions to control light direction. These features create different light transmission properties in different regions, concentrating light where needed (on the keycap) while preventing leakage in other directions

Inventive Principle:
Principle #3Local quality

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 achieves more uniform and efficient illumination of keyboard keys, ensuring that light is distributed effectively across the keycap and surrounding areas, improving visibility and user experience in low-light conditions.

Implementation Method 1

a set of reflection features operative to reflect the light internally around the light guide

Methodology Applied
Scientific EffectInternal reflection: Reflection

Data Source

PatentEP3338291B1Illumination structure for uniform illumination of keys
Publication Date: 2023.10.25 APPLE INC
  • EP3338291B1 patent drawingFigure 1A~1B
  • EP3338291B1 patent drawingFigure 2A~2B
  • EP3338291B1 patent drawingFigure 3

AI summary

An illumination structure for a key of a keyboard is used to uniformly illuminate the key and any glyphs that are present on the key. The illumination structure includes a light guide (310) having reflection features (325) positioned at various locations around the light guide that increase total internal reflection, illumination features (315) or light extraction features that are operative to illuminate the glyphs of the key, and light-directing features (330) to direct light emitted from the light emitting element (335) down one of more paths of the light guide (310).