Reflective Polarizing Plate Reduces Heat in Transmissive Display

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Solution Overview

Problem

Display apparatuses projecting images on transmissive screens face issues with heat generation due to light absorption by polarizing plates, which deteriorates the liquid crystal layer and affects display characteristics.

Innovation Solution

Incorporating a reflective polarizing plate between the light source and the first polarizing plate, with its reflection axis parallel to the absorption axis of the first polarizing plate, to reduce heat generation by reflecting light components that would otherwise be absorbed, and optionally using an IR cut filter to block infrared light and thermal conductive sheets to dissipate heat.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If light from a point light source is made incident to a liquid crystal display element via an optical system consisting of a plurality of lenses to display an image on a spherical screen, then the image brightness is improved, but heat is generated in the liquid crystal display element due to light absorption by polarizing plates, deteriorating display characteristics

Engineering Contradiction:

Improveimage brightnessVSAvoidtemperature rise in liquid crystal display element

Core Design Contradiction:

Illumination intensityVSTemperature

Solution Approach 1:

The patent converts the harmful light component (p-polarized light) that would be absorbed and generate heat into a beneficial reflected component by using a reflective polarizing plate. This reflective plate reflects the p-polarized light component toward the liquid crystal display element while allowing s-polarized light to pass through, thereby reducing heat generation while maintaining image brightness on the spherical screen

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces a reflective polarizing plate as an intermediary component between the light source and the liquid crystal display element. This intermediary selectively reflects specific light components (p-polarized light) while transmitting others (s-polarized light), thereby mediating the light path to reduce heat absorption by the liquid crystal display element while preserving image quality

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If light from the light source is made incident to the liquid crystal display element, then the display function is achieved, but light absorbed by the polarizing plate generates heat that deteriorates the liquid crystal layer characteristics

Engineering Contradiction:

Improveliquid crystal layer characteristicsVSAvoidheat generation from light absorption

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The reflective polarizing plate converts the harmful absorbed light into a beneficial reflected light component. By reflecting p-polarized light toward the liquid crystal display element instead of allowing it to be absorbed, the system reduces heat generation while maintaining the necessary light intensity for reliable display operation

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the optical parameters of the light path by introducing a reflective polarizing plate that selectively reflects p-polarized light. This parameter change in light direction and polarization state reduces the heat load on the liquid crystal layer, thereby improving reliability and extending the operational life of the display element

Inventive Principle:

Principle #35Parameter changes

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 configuration significantly reduces temperature rise in the liquid crystal display element, thereby improving its characteristics and extending its lifespan by minimizing heat-induced deterioration.

Implementation Method 1

a reflective polarizing plate which is provided between the light source and the first polarizing plate and which reflects a light component parallel to a reflection axis among the light from the light source

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

a first polarizing plate provided between the light source and the liquid crystal display element; a second polarizing plate provided between the liquid crystal display element and the screen

Methodology Applied

Scientific EffectPolarisation: Polarisation

Data Source

PatentUS10338456B2Display apparatus with liquid crystal display projecting an image on a transmissive screen

Publication Date: 2019.07.02 ORTUS TECH CO LTD

AI summary

A display apparatus includes: a light source; a liquid crystal display element which transmits light from the light source; a screen which receives projection light from the liquid crystal display element; a first polarizing plate provided between the light source and the liquid crystal display element; a second polarizing plate provided between the liquid crystal display element and the screen; and a reflective polarizing plate which is provided between the light source and the first polarizing plate and which reflects a light component parallel to a reflection axis among the light from the light source.