Back-light Unit Reflective Layer for Uniform LED Illumination
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Solution Overview
Problem
The direct-lit type LED backlights suffer from bright spot defects due to the distance between light emitting diodes, which can be mitigated by increasing the number of LEDs, but this approach raises manufacturing costs.
Innovation Solution
A back-light unit design incorporating a reflective layer, a light transmitting plate with light emitting diodes, and an optical member separated by an air layer, where the light emitting diodes are positioned to reflect light onto the reflective layer and then through the light transmitting plate to the optical member, without increasing the thickness or number of LEDs, using materials like ITO or IZO for the wiring and supporters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the number of LEDs is increased to solve bright spot defects, then the uniformity of light distribution is improved, but the manufacturing cost increases
Solution Approach 1:
A reflective layer is introduced as an intermediary component between the LEDs and the light output. This reflective layer redirects light that would otherwise be lost or create bright spots, distributing it more uniformly across the display area. The reflective layer acts as a mediator that transforms the light distribution pattern without requiring additional LEDs, thereby maintaining manufacturing cost efficiency while improving uniformity.
Solution Approach 2:
The patent modifies the optical parameters of the system by changing the reflectivity characteristics and light path geometry. By adjusting the reflective properties of the reflective layer and the spatial arrangement of light paths, the system achieves more uniform light distribution without increasing LED density, thus avoiding the cost increase associated with adding more LEDs.
2Illumination intensity
If the number of LEDs is increased to reduce distance between light sources, then the white spot defect is reduced, but the device complexity increases
Solution Approach 1:
The reflective layer serves as a mediator that compensates for the limited number of LEDs by redirecting and redistributing light. This intermediary component enables uniform light distribution with fewer LEDs, reducing device complexity while still addressing the white spot defect through improved optical path management.
Solution Approach 2:
Instead of solving the uniformity problem by increasing LED density in the planar dimension, the patent introduces a new dimension - the reflective layer - that adds optical path complexity without increasing component count. This dimensional approach to light distribution allows fewer LEDs to achieve the same uniformity effect that would require more LEDs in a direct configuration.
3Illumination intensity
If the light path length is increased to reduce white spot defects, then the uniformity of light distribution is improved, but the module thickness increases
Solution Approach 1:
The patent uses the reflective layer to create additional optical path length within the existing thickness constraint. By reflecting light multiple times between the LEDs and the reflective layer, the effective light path length is extended without proportionally increasing the physical thickness of the module, thus maintaining thin profile while improving uniformity.
Solution Approach 2:
The optical path parameters are optimized by adjusting the reflectivity and positioning of the reflective layer. This allows the light to travel a longer effective path for diffusion and uniformity without requiring proportional increases in physical thickness, maintaining a balance between optical performance and mechanical constraints.
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
This design effectively reduces white spot defects by increasing the light path length without adding more LEDs, maintaining cost efficiency and module thickness.
Implementation Method 1
light generated from the light emitting diode is reflected by the reflective layer
Implementation Method 2
passes through the light transmitting plate to reach the optical member
Data Source
AI summary
Provided is a back-light unit. The back-light unit includes: a reflective layer; a light transmitting plate including a plurality of light emitting diodes; and an optical member disposed on the light transmitting plate and separated from the light transmitting plate with an air layer therebetween, in which light generated from the light emitting diode is reflected to the reflective layer and then passes through the light transmitting plate to reach the optical member.