Optical Filter for Backlight Brightness Uniformity

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Modern backlighting panels in electronic devices, such as monitors and keyboards, face challenges in achieving uniform brightness due to variations in light emitters and obstructions, requiring complex and costly drive mechanisms to regulate current, which can be inefficient and expensive.

Innovation Solution

An optical filter with individually-tuned cells is applied between the light sources and the surface, reducing light output in discrete regions to achieve predefined luminosity criteria, thereby smoothing irregularities in light distribution without the need for complex drive electronics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If drive electronics are used to regulate current to individual light emitters, then brightness uniformity is improved, but device complexity and cost increase

Engineering Contradiction:

Improvebrightness uniformityVSAvoiddrive electronics complexity

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

An optical filter is introduced as an intermediary component between the light emitters and the display surface. The filter selectively attenuates light from specific emitter positions to compensate for brightness variations, eliminating the need for complex electronic current regulation while achieving uniform brightness distribution.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the electronic control system (drive electronics that regulate current) with an optical control system (filter that attenuates light). This substitution simplifies the overall device by replacing active electronic regulation with passive optical filtering.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Illumination intensity

If individual current regulation is implemented for each light emitter, then brightness uniformity is improved, but manufacturing cost increases

Engineering Contradiction:

Improvebrightness uniformityVSAvoidmanufacturing cost

Core Design Contradiction:

Illumination intensityVSEase of manufacture

Solution Approach 1:

The optical filter is a simple, inexpensive component compared to complex drive electronics for each LED. It can be manufactured cost-effectively using techniques like inkjet printing or photolithography, significantly reducing the per-unit manufacturing cost while achieving the same brightness uniformity goal.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

By using an optical filter as an intermediary, the system avoids the need for expensive individual current regulation circuitry for each light emitter, thereby reducing manufacturing costs while maintaining brightness uniformity.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Area of stationary object

If the number of LEDs is increased and size is decreased, then illumination coverage is improved, but brightness uniformity becomes more difficult to maintain

Engineering Contradiction:

Improveillumination coverageVSAvoidbrightness uniformity

Core Design Contradiction:

Area of stationary objectVSIllumination intensity

Solution Approach 1:

The optical filter is designed with spatially varying transmission characteristics, where different regions of the filter correspond to different light emitter positions. Each region selectively attenuates light from its corresponding emitter to compensate for local brightness variations, enabling uniform illumination even with high-density LED arrays.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The optical filter serves as a mediator that decouples the relationship between LED density and brightness uniformity. By introducing the filter between the LEDs and the display surface, the system can use high-density LEDs for improved coverage while the filter ensures uniform brightness distribution.

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

The optical filter effectively eliminates local hot spots and irregularities, ensuring uniform light distribution while reducing costs and complexity, by aligning filter cells with specific light emitters to adjust their luminance within predetermined thresholds.

Implementation Method 1

applying an optical filter between the multiple light sources and the surface, the optical filter configured to reduce light output within the discrete region

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentUS10908017B2Multiple light source output smoothing

Publication Date: 2021.02.02 MICROSOFT TECHNOLOGY LICENSING LLC

AI summary

In accordance with one implementation, a method for multiple source light output smoothing includes measuring a light distribution generated by multiple light sources arranged within an electronic device and determining at least one brightness adjustment based on the measured light distribution that is sufficient to locally reduce light output within a discrete region of a surface of the electronic device to satisfy predefined luminosity criteria. The method further includes applying an optical filter between the multiple light sources and the surface, the optical filter configured to reduce light output within the discrete region according to the determined at least one brightness adjustment.