Graded Diffuser for LCD Backlight Hotspot Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Backlights in liquid crystal displays (LCDs) face issues with lighting intensity variation near the input edge, leading to undesirable hot spots and artifacts due to the need for high haze uniformity, which can reduce brightness and introduce optical artifacts.
Innovation Solution
A diffuser with opposing major surfaces, where one surface provides a substantially uniform haze and the other surface has a varying haze near the input edge, monotonically decreasing away from the edge, to achieve high brightness without unwanted optical artifacts, and an anti-wetout function to prevent optical defects when placed adjacent to the light guide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a diffuser with uniform haze is used to reduce lighting intensity variation, then hot spot visibility is reduced, but brightness is reduced and optical artifacts are introduced
Solution Approach 1:
The diffuser applies different haze values at different locations: a first haze value near the input edge to control lighting intensity variation, and a second haze value in the central region to maintain brightness. This local differentiation resolves the contradiction by allowing uniform appearance where needed while preserving brightness where important.
Solution Approach 2:
The diffuser is segmented into at least two regions with different haze characteristics: a first region adjacent to the input edge and a second region extending toward the opposite edge. This segmentation allows each region to be optimized independently, reducing hot spots in the first region while maintaining brightness in the second region.
2Stability of the object's composition
If high haze uniformity is applied across the diffuser, then lighting intensity variation is reduced, but optical artifacts are introduced
Solution Approach 1:
Instead of applying uniform haze across the entire diffuser, the invention applies a first haze value in the first region and a second haze value in the second region. This local quality approach maintains sufficient uniformity to reduce lighting variation while avoiding the excessive uniformity that causes optical artifacts.
Solution Approach 2:
The haze value is made dynamic rather than static, varying by location to optimize performance. The first haze value near the edge provides stability for reducing lighting variation, while the second haze value in the central region prevents optical artifacts, creating a dynamically optimized haze distribution.
3Illumination intensity
If a diffuser with varying haze is used to maintain brightness, then brightness is improved, but lighting intensity variation increases
Solution Approach 1:
The diffuser implements local quality by assigning a first haze value to the first region near the input edge to control lighting intensity variation, and a second haze value to the second region to maintain brightness. This resolves the contradiction by localizing the haze variation benefits to where they are most needed.
Solution Approach 2:
The solution moves from a single-dimensional uniform haze approach to a two-dimensional haze distribution approach, varying haze both across the surface and in depth. This dimensional expansion allows simultaneous optimization of brightness and lighting uniformity through spatially differentiated haze values.
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 reduces hotspot visibility while maintaining high brightness and preventing optical artifacts, ensuring uniform light distribution and improved display performance.
Implementation Method 1
forming a first layer of a metal by electrodepositing the metal using a first electroplating process resulting in a first major surface of the first layer having a first average roughness, and forming a second layer of the metal on the first major surface of the first layer by electrodepositing the metal on the first major surface using a second electroplating process
Implementation Method 2
The first major surface includes a first plurality of surface structures providing a substantially uniform first haze, the second major surface includes a first portion adjacent the edge and a second portion adjacent the first portion opposite the edge. The second major surface includes a second plurality of surface structures providing a substantially uniform second haze over the second portion
Data Source
AI summary
A diffuser including opposing structured first and second major surfaces is described. The first major surface includes a first plurality of surface structures providing a uniform first haze. The second major surface includes a first portion adjacent an edge and a second portion adjacent the first portion. The first portion includes a first region and a second region between the first region and the second portion. The second major surface includes a second plurality of surface structures providing a uniform second haze over the second portion and providing a third haze in the first portion. The third haze in the first region is higher than the second haze, and the third haze in the second region is monotonically decreasing. The second portion has a surface area of at least 90 percent of a surface area of the second major surface.