Optical Element with Continuous Tilt Retardation Layers
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Solution Overview
Problem
Existing display devices suffer from light leakage in oblique directions at the azimuths at the top and bottom positions, leading to decreased contrast ratio and unintended color appearance during observation from an oblique direction.
Innovation Solution
An optical element comprising a specific configuration of polarizers and retardation layers, where the tilt angles of anisotropic molecules in the retardation layers change continuously, and the polarizers are aligned relative to the retardation layers to reduce light leakage and color distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a prism sheet is used to focus light from the light source to the front, then light collection efficiency is improved, but side lobe light is generated causing light leakage in oblique directions
Solution Approach 1:
The patent introduces a polarizing plate as an intermediary component between the prism sheet and the liquid crystal panel. This polarizing plate selectively transmits or blocks light based on its polarization state, thereby suppressing side lobe light generated by the prism sheet while maintaining the light collection efficiency of the prism sheet structure
Solution Approach 2:
The patent changes the optical parameters of the system by introducing polarization control. By configuring the polarizing plate with specific transmission axes and combining it with retardation films, the system modifies the polarization state of light to eliminate side lobe light while preserving useful light transmission
2Object-affected harmful factors
If conventional optical elements are used to improve viewability, then external light reflection is reduced, but light leakage in oblique directions and coloring during observation from oblique direction are not addressed
Solution Approach 1:
The patent employs a composite optical structure combining multiple different optical components: a polarizing plate, a first retardation film, a second retardation film, and a prism sheet. This composite structure addresses multiple optical issues simultaneously - external light reflection, side lobe light, and oblique viewing color distortion - by leveraging the complementary properties of each component
3Object-generated harmful factors
If the tilt angles of anisotropic molecules are increased to reduce oblique light transmission, then light leakage is reduced, but color distortion in oblique directions increases
Solution Approach 1:
The patent divides the retardation function into two separate retardation films with different optical characteristics. The first retardation film has anisotropic molecules tilted at angles between 10-30 degrees, while the second retardation film has anisotropic molecules tilted at angles between 45-75 degrees. This segmentation allows each film to address specific aspects of oblique light control without causing excessive color distortion
Solution Approach 2:
The patent applies different tilt angle characteristics to different regions (layers) of the optical system. By configuring the first and second retardation films with distinct tilt angle ranges and optical properties, each layer performs a specialized function in controlling oblique light, achieving overall suppression of light leakage while maintaining color accuracy
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 optical element effectively reduces or prevents light leakage in oblique directions and minimizes color distortion during observation from an oblique angle, thereby enhancing the contrast ratio and image quality.
Implementation Method 1
a first retardation layer containing first anisotropic molecules; a second retardation layer containing second anisotropic molecules
Implementation Method 2
a first polarizer; and a second polarizer, wherein a transmission axis of the first polarizer is parallel to a transmission axis of the second polarizer
Data Source
AI summary
The optical element includes: a first polarizer; a first retardation layer; a second retardation layer; and a second polarizer. First anisotropic molecules near the first polarizer are greater in tilt angle than first anisotropic molecules near an interface with the second retardation layer, with the tilt angles of the first anisotropic molecules continuously changing in a thickness direction. Second anisotropic molecules near the second polarizer are greater in tilt angle than second anisotropic molecules near an interface with the first retardation layer, with the tilt angles of the second anisotropic molecules continuously changing in a thickness direction. Transmission axes of the first and second polarizers are parallel. Slow axes of the first and second retardation layers are parallel. The transmission axis of the first polarizer is parallel to or orthogonal to the slow axes of the first and second retardation layers.