Reflective Sheet Structure for Uniform Backlight Luminance
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Solution Overview
Problem
Light-emitting device packages used in backlight units for display devices suffer from luminance non-uniformity, leading to dark spots and deteriorated optical performance due to low luminance between devices spaced at regular intervals on a circuit board.
Innovation Solution
A light-emitting device package design featuring a circuit board with mounted light-emitting devices, a reflective sheet having openings and inclined portions, and a diffuser plate, where the reflective sheet includes openings penetrating through with inclined and flat extension portions to direct light emitted laterally and prevent dark spots by ensuring uniform luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If light-emitting devices are installed at regular intervals on a circuit board, then device arrangement is simplified and manufacturing is easier, but luminance non-uniformity occurs causing dark spots between devices
Solution Approach 1:
A reflective sheet with a specific optical structure is introduced as an intermediary component between the light-emitting devices and the display surface. This reflective sheet includes inclined portions and flat extension portions that redirect lateral light from each device toward the center regions, serving as a mediator to distribute light more uniformly and eliminate dark spots while maintaining the simple regular interval arrangement of devices
Solution Approach 2:
The reflective sheet features locally differentiated structures: inclined portions positioned adjacent to light-emitting devices that reflect lateral light at specific angles, and flat extension portions that extend toward center regions. This local quality variation in the reflective sheet's structure enables targeted light redirection to different areas, achieving uniform luminance distribution across the display surface
2Area of stationary object
If light-emitting devices are spaced apart to cover large area, then display device area is increased, but luminance between devices decreases causing dark spots
Solution Approach 1:
The reflective sheet acts as an optical intermediary that captures lateral light from each light-emitting device and redirects it toward the center regions between devices. This allows devices to be spaced further apart for larger display areas while the reflective sheet mediates by filling in the luminance gaps that would otherwise create dark spots
Solution Approach 2:
The reflective sheet utilizes three-dimensional geometric structures (inclined portions at specific angles and flat extension portions) to redirect light in new spatial directions. By changing the dimensional approach to light distribution through angular reflection rather than direct lateral emission, the system achieves uniform illumination across larger areas with spaced devices
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 enhances optical efficiency and prevents luminance non-uniformities, resulting in improved display quality and optical performance for backlight units and display devices.
Implementation Method 1
a reflective sheet disposed on the circuit board... an inclined portion surrounding the opening when viewed in a plan view, and being inclined at a first angle with respect to an upper surface of the circuit board
Implementation Method 2
a diffuser plate disposed at a first vertical distance from the upper surface of the circuit board
Data Source
AI summary
A light-emitting device package includes a circuit board, a light-emitting device mounted on the circuit board, a reflective sheet disposed on the circuit board, the reflective sheet including an opening penetrating through the reflective sheet, wherein the light-emitting device is disposed within the opening, an inclined portion surrounding the opening when viewed in a plan view, and being inclined at a first angle with respect to an upper surface of the circuit board, and a flat extension portion surrounding the inclined portion when viewed in a plan view, and being parallel to the upper surface of the circuit board, and a diffuser plate disposed at a first vertical distance from the upper surface of the circuit board. An air gap is disposed between the upper surface of the circuit board and the flat extension portion.