Backlight Unit Reflector Layout for Thin Local Dimming
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Solution Overview
Problem
Conventional backlight units face limitations in thickness reduction and local dimming capabilities, with edge type units restricted by LED chip placement and direct type units limited by thickness reduction and individual operation of LED chips.
Innovation Solution
A backlight unit design featuring a circuit board with light emitting diode chips mounted on it, surrounded by reflective members and a light diffusing member with cavities, allowing for thickness reduction and local dimming by optimizing light emission and reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If light sources are disposed at a side of a light diffusing member (edge type), then the structure is simplified, but thickness reduction of the bezel is limited
Solution Approach 1:
The patent transitions from edge-type lateral light placement to direct-type vertical light placement underneath the light diffusing member. This dimensional change allows the light sources to be positioned in a different spatial arrangement, enabling thickness reduction of the bezel while maintaining illumination functionality.
Solution Approach 2:
Instead of placing light sources at the edges and guiding light through the side surfaces, the patent inverts the approach by placing light sources directly underneath the light diffusing member and guiding light through the lower surface. This inversion enables better thickness control.
2Length of moving object
If light sources are disposed under the light diffusing member (direct type), then thickness reduction is enabled, but individual operation of LED chips is not allowed
Solution Approach 1:
The patent divides the light diffusing member into multiple separate light diffusing members, each corresponding to individual LED chips or groups of chips. This segmentation allows each LED chip to be independently controlled while maintaining the direct-type underneath placement structure, thus enabling both thickness reduction and individual operation.
3Illumination intensity
If distance between light diffusing member and light emitting diode chip is increased, then light distribution is improved, but luminous efficacy is reduced
Solution Approach 1:
The patent introduces reflective members with specific reflective properties positioned at localized areas between the LED chips and light diffusing members. These reflective members have different reflective characteristics in different regions, enabling improved light distribution and extraction efficiency without requiring increased distance, thus maintaining high luminous efficacy.
4Illumination intensity
If multiple reflective members are stacked, then light extraction is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple reflective members into a single integrated reflective member structure. This merged structure maintains the light extraction improvement benefits of multiple reflective layers while reducing the overall structural complexity and simplifying the manufacturing process.
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
Enables uniform light emission with improved luminous efficacy and reduced thickness, minimizing dark spots and allowing individual control of LED chips for enhanced display performance.
Implementation Method 1
The reflective members are stacked and reflect some fraction of light emitted through an upper surface of the light emitting diode chip
Implementation Method 2
a light diffusing member... enhancing light extraction and uniformity by minimizing reflection and separation distances
Data Source
AI summary
The present invention relates to a backlight unit for use in a display device. The backlight unit includes a circuit board, at least one light-emitting diode chip mounted on the circuit board, a plurality of reflection members arranged on the upper part of the light-emitting diode chip, and a light diffusing member. The light diffusing member has an incident surface on which light enters and an emitting surface from which light is emitted. The light diffusing member is arranged on the upper part of the circuit board. The plurality of reflection members are stacked on each other and reflect a part of light emitted from the upper surface of the light-emitting diode chip.