Curved Display Polarizer Axis Alignment for Stress-Induced Contrast Loss
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Solution Overview
Problem
Existing liquid crystal and organic EL displays with curved surfaces face challenges in maintaining optical characteristics, as uniaxially extended polarizing and retardation films deteriorate when subjected to stress, leading to compromised contrast and image quality.
Innovation Solution
The absorption axis of polarizing plates is aligned to match the curvature direction of the display screen, and the extension axis is adjusted based on whether tensile or compressive stress is applied, to prevent deterioration of optical characteristics in liquid crystal displays and enhance contrast in organic EL displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flat liquid crystal display panel is curved by attaching uniaxially extended films and applying heat, then the display panel can be installed on curved surfaces, but the optical characteristics of the polarizing plate and retardation film deteriorate due to stress applied perpendicular to their extension directions
Solution Approach 1:
The patent applies asymmetry by deliberately misaligning the absorption axis of the polarizing plate and the extension axis of the retardation film from the principal stress direction. Specifically, the absorption axis is set at an angle of 5-45 degrees relative to the principal stress direction, creating an asymmetric configuration that prevents stress-induced deterioration of optical characteristics while maintaining curved surface installation capability
Solution Approach 2:
The patent changes the angular parameter of the absorption axis relative to the stress direction from the conventional perpendicular alignment (90 degrees) to a specific range of 5-45 degrees. This parameter change transforms the stress-optical interaction, allowing the display to maintain its optical characteristics under curved surface installation conditions
2Shape
If tension is continuously applied in the direction perpendicular to the extension direction of the polarizing plate, then the liquid crystal display panel can be curved, but the polarization characteristics are deteriorated
Solution Approach 1:
The patent introduces asymmetry by setting the absorption axis at an angle of 5-45 degrees relative to the principal stress direction rather than perpendicular to it. This asymmetric configuration ensures that the stress applied during curved surface formation does not act perpendicular to the absorption axis, thereby preventing deterioration of polarization characteristics while achieving the desired curved shape
3Shape
If a curved glass substrate is used to manufacture a liquid crystal display, then the display can have a curved screen, but the manufacturing process becomes extremely difficult
Solution Approach 1:
The patent applies preliminary action by pre-curving the glass substrate before assembling the liquid crystal display components. This allows the curved screen to be achieved without the complexity of curving the entire assembled display, as the curvature is established in advance on the substrate level, simplifying the overall manufacturing process
Solution Approach 2:
The patent segments the manufacturing process into distinct stages: first curving the glass substrate independently, then assembling the liquid crystal components on the pre-curved substrate. This segmentation allows each component to be manufactured separately under optimal conditions and assembled afterward, avoiding the complexity of manufacturing the entire curved display as a single integrated unit
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 effectively suppresses changes in polarization characteristics, ensuring reliable image quality and contrast for liquid crystal displays and organic EL displays with curved surfaces over time.
Implementation Method 1
a liquid crystal display panel having a curved surface using a phenomenon that a polarizing plate is curved toward an absorption axis according to temperature and humidity
Implementation Method 2
a technology that, when a flat liquid crystal display panel is curved, attaches a uniaxially extended film onto a concave surface side, and leaves the liquid crystal display panel under an atmosphere at 40° C. to 200° C. for 10 minutes to 24 hours, thereby curving the liquid crystal display panel. That is, the liquid crystal display panel is curved by using a phenomenon that the uniaxially extended film is contracted in the extension direction.
Data Source
AI summary
Disclosed is a liquid display device that is capable of suppressing a change in contrast of a liquid crystal display panel, in which a screen is a curved surface with a curvature in one direction. In a liquid crystal display panel having a cylindrical surface, an upper polarizing plate is attached to a color filter substrate. The upper polarizing plate receives tensile stress in a curved direction. Tensile stress adversely affects polarization characteristics of the upper polarizing plate. According to an embodiment of the invention, if the absorption axis A of the upper polarizing plate is adapted to match with the curved direction of the liquid crystal display panel, it is possible to prevent a change in polarization characteristics of the upper polarizing plate. As a result, it is possible to obtain an image with excellent contrast for a long term.