Backlight Reflective Polarizer and Diffuser Integration

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Solution Overview

Problem

Head-up displays for motor vehicles using liquid-crystal displays (LCDs) are exposed to thermal stresses from light sources and concentrated solar rays, leading to heating issues that require effective management to preserve the sensitive LCD components.

Innovation Solution

A back-lighting device is designed with a light source, a reflector, and an integrally formed component comprising a reflective polarizer and an optical diffuser. The reflective polarizer is positioned facing the light source to improve light recycling, and the optical diffuser is engraved on a transparent substrate to prevent stray light from entering the reflective polarizer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the reflective polarizer is positioned facing the light source, then light recycling is improved, but exterior light may directly reach the reflective polarizer causing stray light

Engineering Contradiction:

Improvelight recycling efficiencyVSAvoidstray light from exterior light

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

An optical diffuser is introduced as an intermediary element positioned between the light source and the reflective polarizer. This diffuser scatters the light path so that exterior light reaching the component does not directly reach the reflective polarizer, preventing stray light while allowing the reflective polarizer to maintain its light recycling function.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The component is divided into functionally distinct sides: a first side with the reflective polarizer for light recycling and a second side with the optical diffuser for preventing stray light. This segmentation allows each side to perform its specific function independently while working together as an integrated component.

Inventive Principle:

Principle #1Segmentation

2Object-affected harmful factors

If the optical diffuser is added to prevent stray light, then stray light is reduced, but the device complexity increases

Engineering Contradiction:

Improvestray lightVSAvoidcomponent structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The reflective polarizer and optical diffuser are merged into a single integrally formed component with distinct functional sides. This combining approach reduces the total number of separate parts and assembly steps while maintaining the stray light prevention function, thereby limiting the increase in device complexity.

Inventive Principle:

Principle #5Merging (Combining)

3Illumination intensity

If light recycling is improved by positioning the reflective polarizer facing the light source, then transmission of light is improved, but heating of the LCD increases

Engineering Contradiction:

Improvelight transmissionVSAvoidLCD heating

Core Design Contradiction:

Illumination intensityVSTemperature

Solution Approach 1:

The optical diffuser acts as a mediator that modifies the light path to prevent exterior light from directly reaching the reflective polarizer. This reduces the thermal load on the LCD while maintaining the light recycling efficiency provided by the reflective polarizer's positioning.

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 solution enhances light recycling within the back-lighting device, improves light transmission, and reduces stray light, thereby minimizing heating of the LCD and maintaining its performance effectively.

Implementation Method 1

a reflector configured to reflect at least a part of the source beam into a reflected beam

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

an integrally formed component comprising, on a first side, a reflective polarizer

Methodology Applied

Scientific EffectPolarization: Polarisation

Implementation Method 3

on a second side opposite the first side, an optical diffuser

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS20250138311A1Backlight device and associated image generation device, head-up display, and manufacturing method

Publication Date: 2025.05.01 VALEO COMFORT & DRIVING ASSISTANCE

AI summary

A back-lighting device comprises a light source configured to emit a source beam, a reflector configured to reflect at least a part of the source beam into a reflected beam, an integrally formed component comprising, on a first side, a reflective polarizer and, on a second side opposite the first side, an optical diffuser, said component being configured to receive and transmit at least a part of the reflected beam, characterized in that the first side of the component is placed facing the light source. An image-generating device, a head-up display and a process for manufacturing a component for the back-lighting device are disclosed herein.