Light Flux Controlling Member for LCD Uniformity
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Solution Overview
Problem
Conventional light-emitting devices for liquid crystal display panels face issues with uneven brightness due to high Fresnel reflection, leading to reduced light scattering ability and concentrated bright spots or rings, which are difficult to prevent with existing light flux controlling members.
Innovation Solution
A light-emitting device with a light flux controlling member that has a specific light-incoming and light-outgoing surface design, where the light distribution follows a Gaussian pattern, achieved by satisfying certain integral equations, to refract light away from the light axis and distribute it uniformly across the liquid crystal display panel, thereby reducing Fresnel reflection and enhancing scattering ability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional light flux controlling member is used, then light can be emitted from the light-emitting element, but uneven brightness occurs due to high Fresnel reflection and concentrated bright spots or rings
Solution Approach 1:
The light flux controlling member employs a curved light-outgoing surface with a specific radius of curvature that is greater than the distance from the light-emitting element to the light-outgoing surface. This curvature design refracts light rays at different angles, causing them to diverge and distribute uniformly across the liquid crystal display panel, thereby preventing concentrated bright spots or rings and eliminating uneven brightness caused by high Fresnel reflection.
2Illumination intensity
If the light flux is broadened over a wide range, then uniform brightness is achieved, but light scattering ability is reduced
Solution Approach 1:
The invention optimizes the radius of curvature parameter of the light-outgoing surface to be greater than the distance from the light-emitting element to the light-outgoing surface. This parameter change enables the light flux controlling member to refract light at appropriate angles, achieving both uniform brightness distribution and high light scattering ability by preventing light concentration while maintaining broad light flux coverage.
3Reliability
If light is refracted away from the light axis, then light scattering ability is enhanced, but reflectance increases
Solution Approach 1:
The curved light-outgoing surface with a radius of curvature greater than the distance to the panel refracts light rays away from the light axis at controlled angles. This curvature design enhances light scattering ability by distributing light uniformly across the panel while minimizing reflectance losses, as the refracted light rays are directed toward the panel rather than being reflected back into the light flux controlling member.
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 effectively prevents uneven brightness and achieves higher light scattering ability by refracting light closer to perpendicular to the light axis, improving the distribution of light across the panel and reducing reflectance to 15% or lower, thus enhancing the overall lighting performance.
Implementation Method 1
a light flux controlling member 2 for controlling light emitted from the light-emitting element 1, the light flux controlling member having (i) a light-incoming surface 2a from which the light emitted from the light-emitting element enters the light flux controlling member and (ii) a light-outgoing surface 2b from which the light being incident on the light-incoming surface is emitted from the light flux controlling member
Implementation Method 2
uneven brightness due to high Fresnel reflection, leading to reduced light scattering ability and concentrated bright spots or rings, which are difficult to prevent with existing light flux controlling members
Data Source
AI summary
A light-emitting device (10) includes: a light-emitting element (1); and a light flux controlling member (2) for controlling light emitted from the light-emitting element (1), the light flux controlling member (2) has (i) a light-incoming surface (2a) which the light emitted from the light-emitting element (1) enters and (ii) a light-outgoing surface (2b), and the following equation (1) is satisfied where r is a length, from a light axis Z of the light-emitting device (10), of a plane that is provided at a certain distance from the light flux controlling member (2) in a direction parallel to the light axis Z so as to be perpendicular to the light axis Z, φ1 is an angle between the light emitted from the light-emitting element (1) and the light axis, P(φ1) is a light distribution property of the light-emitting element (1). This provides a light-emitting device that scatters light without generating uneven brightness on a liquid crystal display panel, reduces a reflectance caused by the Fresnel's reflection, and has an improved scattering ability.