Side-Emitting LED Package Layout for Thin Uniform LCD Backlights
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Solution Overview
Problem
Liquid crystal displays (LCDs) face challenges with high power consumption due to the need for a constant light source from the backlight unit, and they struggle with achieving uniform light distribution and clear blackout effects in direct-lighting type backlight units.
Innovation Solution
The proposed solution involves a light emitting device with a light emitting diode chip, a light reflection member on its upper surface, a light transmitting resin covering its side surfaces, and a light blocking member covering the upper surface of the resin. This configuration enhances light distribution and reduces power consumption by allowing light to be emitted more uniformly through the side surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple light emitting diodes are arranged in a matrix below the display panel to achieve uniform light distribution, then light uniformity is improved, but the thickness of the backlight unit increases due to the need for diffusion lenses and increased distance between light source and optical sheet
Solution Approach 1:
The patent transitions from traditional bottom-emitting LED arrangement to side-emitting LED configuration, changing the emission dimension from vertical (upward through optical sheet) to lateral (through side surfaces). This dimensional change eliminates the need for diffusion lenses and reduces the distance requirement between light source and optical sheet, thereby reducing backlight unit thickness while maintaining light uniformity
Solution Approach 2:
The patent applies different structural configurations to different parts of the LED package: the light emitting diode chip emits light through side surfaces, the light transmitting resin is specifically positioned to cover and transmit light from these side surfaces, and the light blocking member is strategically placed to prevent unwanted light emission directions. This localized optimization achieves uniform light distribution without requiring increased thickness
2Illumination intensity
If a diffusion lens is used to achieve uniform spreading of light emitted from light emitting diodes, then light uniformity is improved, but the thickness of the backlight unit increases
Solution Approach 1:
The patent extracts and eliminates the diffusion lens component from the backlight unit by changing to side-emitting LEDs that inherently provide uniform light distribution through their emission geometry. The light transmitting resin positioned at the side surfaces replaces the function of diffusion lenses, achieving light uniformity without the additional thickness required by traditional diffusion optics
3Device complexity
If the region covered by one light emitting diode is increased to reduce the number of light emitting diodes, then device complexity is reduced, but the ability to achieve clear blackout effects in local dimming is worsened
Solution Approach 1:
The patent enhances the segmentation capability by using side-emitting LEDs with precisely controlled light emission through light transmitting resin positioned at specific side surfaces. This configuration creates well-defined light boundaries that improve blackout effect clarity, allowing for effective local dimming with fewer LEDs while maintaining precise light control in different regions
4Length of stationary object
If light emitting diodes are positioned close to the display panel to reduce thickness, then backlight unit thickness is reduced, but uniform light distribution becomes difficult to achieve
Solution Approach 1:
The patent changes the light emission dimension from vertical (requiring distance for uniformity) to lateral (emitting through side surfaces). This dimensional change allows the LED to be positioned close to the display panel while maintaining uniform light distribution, as the light spreads uniformly in the lateral direction through the light transmitting resin without requiring vertical distance
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 configuration effectively suppresses the spot phenomenon, improves luminous uniformity, and allows for clear blackout effects and local dimming in LCDs, reducing power consumption and enhancing contrast ratios.
Implementation Method 1
a light reflection member on its upper surface
Implementation Method 2
a light transmitting resin covering its side surfaces
Implementation Method 3
a light blocking member covering the upper surface of the resin
Data Source
AI summary
A display apparatus including a display panel, and a backlight to provide light toward the display panel, the backlight including a circuit board, an optical layer disposed on the circuit board, at least one light emitter disposed between the circuit board and the optical layer and including a light emitting structure disposed on the circuit board and having first and second conductivity type semiconductor layers and an active layer therebetween, first and second electrode pads electrically connected to the first and second conductivity type semiconductor layers, respectively, a reflector on the light emitting structure, a light transmitting layer disposed on the circuit board and contacting the light emitter, and a dam disposed on the circuit board and surrounding the light emitter and including a portion having a curved shape.