LED Backlight Cavity Structure for Thin Local Dimming Displays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing backlight units face limitations in thickness reduction, particularly in edge and direct types, and lack the ability for local dimming and improved luminous efficacy due to the arrangement of light sources and light diffusing members.
Innovation Solution
A backlight unit design featuring a circuit board with light emitting diode chips mounted in cavities within a light diffusing member, surrounded by reflective members, allowing for thickness reduction and enabling local dimming through uniform light distribution and improved light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If light sources are disposed at a side of a light diffusing member (edge type), then the structure is compact, but thickness reduction of the bezel is limited
Solution Approach 1:
The patent transitions from edge-type lateral light arrangement to direct-type vertical light arrangement beneath the light diffusing member, changing the spatial dimension of light source placement. This enables thickness reduction in the vertical direction while maintaining compactness through optimized cavity integration.
2Length of moving object
If light sources are disposed under the light diffusing member (direct type), then thickness reduction is enabled, but the structure becomes more complex and individual LED operation is limited
Solution Approach 1:
The patent divides the light diffusing member into multiple cavities, each housing individual LED chips and reflective members. This segmentation enables independent control of each LED while maintaining a unified diffusing structure, resolving the conflict between thickness reduction and individual LED operability.
Solution Approach 2:
The patent nests reflective members within the cavities of the light diffusing member, placing them in close proximity to LED chips. This nested arrangement optimizes light extraction efficiency within the reduced thickness while maintaining structural integration.
3Use of energy by moving object
If distance between light diffusing member and LED chip is reduced, then luminous efficacy is improved, but light extraction efficiency may be compromised
Solution Approach 1:
The patent places reflective members inside the cavities of the light diffusing member in direct proximity to LED chips, creating a nested configuration. This minimizes the air gap between LED and diffusing member, reducing light loss and improving both luminous efficacy and light extraction efficiency simultaneously.
Solution Approach 2:
The patent uses reflective members to convert light that would otherwise be lost at the LED-diffusing member interface into useful forward-directed light. This transforms potential energy loss into beneficial light output, improving overall luminous efficacy.
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 design achieves thickness reduction in display devices, enables local dimming for individual control of LED chips, and enhances light uniformity and extraction efficiency by minimizing light loss at interfaces.
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 having a light incident surface on which light is incident and a light exit surface through which light is emitted
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.