Projector Optical Path Shifting for Red Band Color Accuracy

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Solution Overview

Problem

Existing projectors face issues with reduced response speed and color deviation due to thin liquid crystal layers, leading to decreased brightness and color tone quality, particularly in the red wavelength band.

Innovation Solution

The projector employs multiple liquid crystal panels with varying thicknesses and frame rates, combined with a biaxial or uniaxial optical shifting device to manage optical paths, ensuring optimal rotation efficiency and frame rates for each color band, thereby maintaining color accuracy and brightness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the thickness of the liquid crystal layer is reduced to increase response speed, then the response speed is improved, but the rotation efficiency in the red wavelength band decreases leading to color deviation and brightness loss

Engineering Contradiction:
Improveresponse speedVSAvoidcolor tone accuracy
Core Design Contradiction:
SpeedVSManufacturing precision

Solution Approach 1:

The invention divides the liquid crystal display system into multiple panels with different liquid crystal layer thicknesses, where the first liquid crystal panel has a first thickness and the second liquid crystal panel has a second thickness greater than the first thickness. This segmentation allows each panel to be optimized for specific wavelength bands, preventing color deviation while maintaining high response speeds.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the optical system are assigned different liquid crystal layer thicknesses based on their functional requirements. The first liquid crystal panel uses a thinner layer for high-speed response in certain wavelength bands, while the second liquid crystal panel uses a thicker layer to maintain rotation efficiency in the red wavelength band, thereby achieving local optimization of both speed and color accuracy.

Inventive Principle:
Principle #3Local quality

2Speed

If the thickness of the liquid crystal layer is reduced to increase response speed, then the response speed is improved, but the brightness decreases

Engineering Contradiction:
Improveresponse speedVSAvoidbrightness
Core Design Contradiction:
SpeedVSIllumination intensity

Solution Approach 1:

The invention divides the liquid crystal display system into multiple panels with different liquid crystal layer thicknesses, where the first liquid crystal panel has a first thickness and the second liquid crystal panel has a second thickness greater than the first thickness. This segmentation allows each panel to be optimized for specific wavelength bands, preventing color deviation while maintaining high response speeds.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the optical system are assigned different liquid crystal layer thicknesses based on their functional requirements. The first liquid crystal panel uses a thinner layer for high-speed response in certain wavelength bands, while the second liquid crystal panel uses a thicker layer to maintain rotation efficiency in the red wavelength band, thereby achieving local optimization of both speed and color accuracy.

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If different liquid crystal layer thicknesses are used for different wavelength bands, then color accuracy is maintained, but the device complexity increases

Engineering Contradiction:
Improvecolor tone accuracyVSAvoidpanel configuration complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention divides the liquid crystal display system into multiple panels with different liquid crystal layer thicknesses, where the first liquid crystal panel has a first thickness and the second liquid crystal panel has a second thickness greater than the first thickness. This segmentation allows each panel to be optimized for specific wavelength bands, preventing color deviation while maintaining high response speeds.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention combines multiple liquid crystal panels with different thickness characteristics into a single integrated display system. By merging the first liquid crystal panel (thinner layer) and the second liquid crystal panel (thicker layer) with a light combining element, the system achieves both high response speed and accurate color reproduction without requiring complex external control mechanisms.

Inventive Principle:
Principle #5Merging (Combining)

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 maintains high definition and brightness by preventing color deviation and brightness loss, even with slower response speeds in certain panels, by optimizing the thickness and frame rates of liquid crystal layers for each color band.

Implementation Method 1

a first liquid crystal panel configured to modulate light in a first wavelength band to generate first image light, a second liquid crystal panel configured to modulate light in a second wavelength band having a center wavelength longer than a center wavelength of the first wavelength band to generate second image light

Methodology Applied
Scientific EffectLiquid crystal rotation: Liquid Crystals

Implementation Method 2

the rotation efficiency of the liquid crystal is maximized shifts to the short wavelength side. As a result, in particular, the rotation efficiency in the red wavelength band decreases

Methodology Applied
Scientific EffectOptical rotation: Birefringence

Implementation Method 3

a light combining element configured to combine the first image light and the second image light to generate composite image light

Methodology Applied
Scientific EffectOptical path combination: Refraction

Data Source

PatentEP4692925A1projector
Publication Date: 2026.02.11 SEIKO EPSON CORP
  • EP4692925A1 patent drawingFigure 1
  • EP4692925A1 patent drawingFigure 2~3
  • EP4692925A1 patent drawingFigure 4

AI summary

A projector includes a first liquid crystal panel configured to modulate light in a first wavelength band to generate first image light, a second liquid crystal panel configured to modulate light in a second wavelength band having a center wavelength longer than a center wavelength of the first wavelength band to generate second image light, a light combining element configured to combine the first image light and the second image light to generate composite image light, a projection optical system configured to project the composite image light, and an optical shifting device configured to shift an optical path of at least one of the first image light, the second image light, and the composite image light, wherein a thickness of a liquid crystal layer of the second liquid crystal panel is larger than a thickness of a liquid crystal layer of the first liquid crystal panel, and a frame rate of the first liquid crystal panel is higher than a frame rate of the second liquid crystal panel.