Variable Transmissive Film for LED Light Intensity Control

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Solution Overview

Problem

Current light emitting devices, particularly those using LEDs, face limitations in achieving low light levels through PWM dimming and suffer from inconsistent light color with analog dimming, necessitating an improved method for controlling light output.

Innovation Solution

A light emitting device incorporating a variable transmissive film with encapsulated dispersion containing electrically charged particles and a fluid, which can switch between open and closed states under an electric field, allowing for controlled light transmission without the need for PWM or analog dimming, and enabling seamless transitions between different lighting modes without mechanical components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If PWM dimming is used to achieve low light levels, then energy consumption is reduced, but the minimum achievable light level is limited and cannot reach true darkness

Engineering Contradiction:

Improveenergy consumptionVSAvoidminimum light level

Core Design Contradiction:

Use of energy by moving objectVSIllumination intensity

Solution Approach 1:

The patent replaces the electrical PWM dimming system with a mechanical/optical system using a variable transmissive film that can physically block light transmission. This film acts as a mechanical shutter that can achieve complete darkness by blocking all light, overcoming the limitation of PWM which can only reduce but not completely eliminate light output.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The variable transmissive film serves as an intermediary element between the LED light source and the environment. This film mediates the light transmission by providing an additional control layer that can independently block or transmit light, allowing the system to achieve complete darkness regardless of the LED's operational state.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If analog dimming is used to vary light output, then continuous dimming control is achieved, but light color becomes inconsistent and changes with current levels

Engineering Contradiction:

Improvedimming controlVSAvoidlight color consistency

Core Design Contradiction:

Ease of operationVSIllumination intensity

Solution Approach 1:

The patent separates the dimming control function from the light generation function. The LED operates at constant current to maintain consistent color, while the variable transmissive film is segmented into controllable regions that independently modulate light transmission. This segmentation allows dimming control without affecting the LED's color output.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces electrical current modulation (analog dimming) with a mechanical/optical modulation system using the variable transmissive film. This substitution decouples the dimming control from the electrical current, allowing continuous dimming control while maintaining constant LED operating conditions and consistent light color.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If mechanical components are used for focusing light, then light direction and intensity can be controlled, but device complexity and failure points increase

Engineering Contradiction:

Improvelight controlVSAvoidmechanical components

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent replaces mechanical focusing components (such as movable lenses or mirrors) with an electro-optic system using the variable transmissive film. The film's optical properties are controlled by electrical signals rather than mechanical movement, eliminating complex mechanical assemblies and their associated failure points while maintaining light control capabilities.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses a dynamic electro-optic system where the variable transmissive film can rapidly change its optical state in response to electrical signals. This dynamic control achieves light modulation without mechanical movement, providing fast response times and reliability while reducing device complexity.

Inventive Principle:

Principle #15Dynamics

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 solution provides a reliable and energy-efficient method for dimming LED light sources, offering consistent light color and adjustable light levels, reducing energy consumption and heat generation, while eliminating the need for mechanical focusing components.

Implementation Method 1

the charged particles being movable by application of an electric field and capable of being switched between an open state and a closed state

Methodology Applied

Scientific EffectElectrophoresis: Electrophoresis

Data Source

PatentUS11333323B2Light emitting device including variable transmission film to control intensity and pattern

Publication Date: 2022.05.17 E INK CORP

AI summary

A lamp includes a variable transmissive film and a light source arranged to transmit light through the variable transmissive film. The variable transmissive film includes an encapsulated dispersion containing a plurality of electrically charged particles and a fluid, the charged particles being movable by application of an electric field and capable of being switched between an open state and a diffusing state. In some embodiments, one portion of the variable transmission film is in the open state and one portion is in the closed state, thereby allowing light from the source to be shaped, e.g., into task lighting.