Chip-Scale Linear LED Packaging for Uniform Backlight Emission
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Solution Overview
Problem
Conventional LED light bars in thinner backlight modules for bevel-less displays suffer from non-uniform light distribution, leading to dark regions on the light guide plate, and alignment challenges due to the miniaturization and top-view configuration of LED semiconductor chips.
Innovation Solution
A chip-scale linear light-emitting device with a side-view or top-view configuration, featuring a submount substrate with flip-chip LED semiconductor chips, a chip-scale packaging structure, and a reflective structure, which creates a continuous optical cavity for uniform light distribution and alignment with the light guide plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If LEDs are non-continuously disposed on the submount substrate to form an LED light bar, then the device complexity is reduced and manufacturing is simplified, but the light beam intensity becomes non-uniform and dark regions occur on the light guide plate
Solution Approach 1:
A light-transmitting element is introduced as an intermediary component between the discontinuously disposed LEDs and the light guide plate. This element fills the gaps between LEDs and transmits light uniformly across the entire surface, mediating between the simplified LED arrangement and the required uniform illumination, thereby eliminating dark regions while maintaining manufacturing simplicity
Solution Approach 2:
The light-transmitting element is designed with uniform optical properties throughout its structure. By making the element homogeneous in material composition and thickness, light from the discontinuously disposed LEDs is evenly distributed across the light guide plate, achieving uniform illumination intensity without requiring complex LED positioning
2Length of stationary object
If the light mixing distance between the LED light bar and the edge of the effective display area is reduced to achieve thinner backlight modules, then the thickness of the backlight module is reduced, but the dark areas of the light guide plate become more visible
Solution Approach 1:
The light-transmitting element acts as a mediator that enables effective light mixing over a reduced distance. By incorporating this element with optimized optical properties, the light mixing distance is shortened while maintaining uniform light distribution, allowing the backlight module to be thinner without exacerbating dark area visibility
3Length of stationary object
If the LED light bar is miniaturized and configured in top-view structure to achieve thinner backlight modules, then the thickness is reduced, but alignment accuracy with the light guide plate deteriorates and light leakage occurs
Solution Approach 1:
The invention transitions from a top-view configuration to a side-view configuration, changing the spatial dimension of light emission. In the side-view type, the light-emitting surface is positioned laterally adjacent to the light guide plate, enabling accurate alignment through edge positioning while maintaining miniaturization and thin profile, thereby improving alignment accuracy without sacrificing thickness reduction
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 achieves a uniformly distributed linear light radiation pattern, reducing dark regions on the light guide plate and enabling accurate alignment of miniaturized LED light bars with thin light guide plates, thus enhancing the uniformity and efficiency of the backlight module.
Implementation Method 1
a reflective structure (14), wherein the reflective structure (14) is disposed on the submount substrate (11) and covers the first chip-edge surfaces (1231) of the LED semiconductor chips (12), the chip-upper surfaces (121) of the LED semiconductor chips (12), and the package-top surface (131) of the packaging structure (13)
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A chip-scale linear light-emitting device (10A; 10B; 10C; 10D; 10E; 10F; 10G) includes a submount substrate (11), light-emitting diode (LED) semiconductor chips (12), a chip-scale packaging structure (13; 13') and a reflective structure (14; 14'). The LED semiconductor chips (12), the packaging structure (13; 13') and the reflective structure (14; 14') are disposed on the submount substrate (11), wherein the packaging structure (13; 13') covers a chip-upper surface (121) and/or at least one of chip-edge surfaces (1231, 1232, 1233, 1234) of the LED semiconductor chips (12), and the reflective structure (14; 14') covers at least a package-top surface (131) or at least package-side surfaces (132') of the packaging structure (13; 13'). If one of the chip-edge surfaces (1231, 1232, 1233, 1234) and a package-side surface of the packaging structure (13) are exposed from the reflective structure (14) as a light-emitting side surface (132), a side-view type linear light-emitting device is formed. If the chip-upper surface (121) and the package-top surface of the packaging structure (13') are exposed from the reflective structure (14') as a light-emitting top surface (131'), a top-view type linear light-emitting device is formed. A substantially transparent light-transmitting material and/or a photoluminescent material can be configured to be included inside the packaging structure (13; 13'). In this configuration, a primary light emitted from the LED semiconductor chips (12) is directed to pass through the packaging structure (13; 13') and radiated outward from a primary light-emitting surface. Therefore, a monochromatic light or a white light with a uniformly distributed linear radiation pattern can be generated using the chip-scale linear light-emitting device (10A; 10B; 10C; 10D; 10E; 10F; 10G).