Circularly Polarizing Plate with Optimized λ/2 and λ/4 Plates

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Solution Overview

Problem

Conventional circularly polarizing plates, especially those incorporating broadband λ/4 plates, fail to effectively reduce outside light reflection in tilt directions due to deviations in optical axis angles, leading to inadequate performance compared to front-direction reductions.

Innovation Solution

A circularly polarizing plate design where the absorption axis of the polarizing film, the λ/2 plate, and the λ/4 plate are aligned such that the angles between them are confined within specific ranges, with the λ/2 plate and λ/4 plate having different wavelength dispersions and optical uniaxiality, ensuring effective light phase differences across a wide wavelength range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a broadband λ/4 plate is used to achieve wide wavelength range reflection reduction, then the wavelength range for effective reflection reduction is improved, but the deviation of apparent optical axes in tilt directions increases, worsening the reflection reduction ability in tilt directions

Engineering Contradiction:

Improvewavelength range for reflection reductionVSAvoidreflection reduction ability in tilt direction

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent optimizes specific parameters including the angle between the absorption axis of the polarizing film and the slow axis of the λ/2 plate (22.5°±10°), the angle between the absorption axis of the polarizing film and the slow axis of the λ/4 plate (90°±20°), and the wavelength dispersion relationship between the two plates. These parameter optimizations ensure that the broadband λ/4 plate maintains effective reflection reduction in both front and tilt directions across a wide wavelength range.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If multiple optical plates (λ/2 plate and λ/4 plate) are combined to achieve broadband performance, then the wavelength range is improved, but the number of optical axes increases, making angle adjustment more complex and worsening the stability of optical axis angles

Engineering Contradiction:

Improvebroadband performanceVSAvoidnumber of optical axes

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines a polarizing film, a λ/2 plate, and a λ/4 plate into a single circularly polarizing plate assembly. By integrating these components with specifically optimized angular relationships, the invention achieves broadband performance while managing the complexity of multiple optical axes through unified design and fabrication processes.

Inventive Principle:

Principle #5Merging (Combining)

3Measurement precision

If the slow axis of the λ/2 plate is set at 22.5° relative to the absorption axis of the polarizing film, then the phase difference for front direction is improved, but the apparent angle deviation in tilt directions increases, worsening the reflection reduction in tilt directions

Engineering Contradiction:

Improvephase difference accuracy in front directionVSAvoidreflection reduction ability in tilt direction

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent optimizes the angle parameter between the slow axis of the λ/2 plate and the absorption axis of the polarizing film to 22.5°±10°. This specific angular parameter, combined with the optimized angle for the λ/4 plate (90°±20°), ensures that the circularly polarizing plate maintains effective reflection reduction in both front and tilt directions across a wide wavelength range.

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

The solution enables the circularly polarizing plate to effectively reduce outside light reflection in both front and tilt directions, enhancing its antireflective capabilities across a wide wavelength range.

Implementation Method 1

a λ/2 plate having a slow axis in a direction forming an angle of 22.5°±10° relative to an absorption axis of the polarizing film; a λ/4 plate having a slow axis in a direction forming an angle of 90°±20° relative to the absorption axis of the polarizing film

Methodology Applied

Scientific EffectBirefringence: Birefringence

Implementation Method 2

a polarizing film; a λ/2 plate having a slow axis in a direction forming an angle of 22.5°±10° relative to an absorption axis of the polarizing film

Methodology Applied

Scientific EffectDichroism: Dichroic Filter

Data Source

PatentUS10310286B2Circularly polarizing plate, method for producing same, broadband lambda/4 plate, organic electroluminescent display device, and liquid crystal display device

Publication Date: 2019.06.04 ZEON CORP

AI summary

A circularly polarizing plate including a polarizing film, a λ/2 plate having a slow axis in a direction forming an angle of 22.5°±10° relative to an absorption axis of the polarizing film, a λ/4 plate having a slow axis in a direction forming an angle of 90°±20° relative to the absorption axis of the polarizing film, in this order, wherein the λ/2 plate and the λ/4 plate have different wavelength dispersions, an NZ factor of the λ/2 plate is 1.00±0.05, and an NZ factor of the λ/4 plate is 0.00±0.05; a method for producing the same, and a method for using the same.