LED Lighting Device with Flat Reflective Member for Light Guide Plate
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Solution Overview
Problem
Conventional lighting devices for non-self-emitting displays, such as liquid crystal displays, face challenges in achieving a low-profile design while maintaining high illumination efficiency, as reducing the thickness of the light guide plate leads to decreased light intake and increased dark or low-brightness regions between LEDs.
Innovation Solution
The solution involves a lighting device with a light guide plate and an LED unit where the LED unit has a transparent or translucent emission section with a substrate and a flat reflective member covering the top surface adjacent to the light guide plate, allowing for effective reflection and emission of light from all sides, including a reflective sheet beneath the light guide plate to collect and redirect otherwise lost light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the thickness of the light guide plate is reduced to achieve a low-profile design, then the overall device thickness is reduced, but the light intake efficiency decreases and dark regions appear between LEDs
Solution Approach 1:
The invention redirects light propagation from primarily lateral (X-axis) to include significant vertical (Z-axis) components by tilting the light guide plate and positioning LEDs above it. This dimensional change allows thin light guide plates to still capture sufficient light by receiving it from overhead rather than solely from the side, resolving the contradiction between reduced thickness and maintained light intake efficiency.
Solution Approach 2:
A reflective member is introduced as an intermediary between the LEDs and the light guide plate. This reflective member redirects light that would otherwise be lost downward or laterally into the light guide plate, significantly improving light capture efficiency even when the plate is thin. The reflector acts as a mediator that enhances the interaction between the light source and the light guide structure.
2Illumination intensity
If conventional LED units with light shielding walls are used, then light is directed forward, but light leaking from top and bottom surfaces is wasted and manufacturing complexity increases
Solution Approach 1:
The invention removes the light shielding wall from the LED unit structure, extracting this component entirely. Instead of using complex shielding structures to control light direction, the design relies on the reflective member and the tilted light guide plate geometry to achieve the desired light distribution, thereby simplifying manufacturing while maintaining illumination effectiveness.
Solution Approach 2:
The invention converts the previously harmful light leakage from the top and bottom LED surfaces into a beneficial resource. By positioning the light guide plate at a tilt and using reflective members, light that would normally be wasted is now redirected into the light guide plate, improving overall light utilization efficiency while eliminating the need for complex shielding structures.
3Loss of energy
If reflective members are formed on the circumferential surface of LED emission sections, then light is reflected back, but manufacturing cost and complexity increase
Solution Approach 1:
The reflective function is segmented from the LED unit itself and placed as a separate, independent component. Instead of forming reflective members directly on the LED circumferential surfaces (which would require complex integrated manufacturing), the reflective member is positioned separately in the light guide plate structure, allowing standard LED manufacturing processes to be used while still achieving effective light reflection through the separate reflective component.
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 enhances light utilization and emission efficiency, preventing dark regions and maintaining illumination intensity even when the light guide plate is significantly thinned, resulting in a low-profile, cost-effective, and bright lighting solution.
Implementation Method 1
a flat reflective member provided separately from the LED unit and disposed over a top side of the circumferential surface and extending in parallel with the top surface of the light guide plate so as to cover a region of the top surface of the light guide plate adjacent to the light entering surface of the light guide plate
Implementation Method 2
A light 15 from the LED unit 64 that has entered the light guide plate 10 advances in the light guide plate 10 while repeatedly bouncing between reflective prisms 62 arranged in the lower surface of the light guide plate and an upper surface of the light guide plate
Implementation Method 3
an LED chip embedded within the emission section
Data Source
AI summary
A lighting device for a liquid crystal display and the like comprises: a light guide plate having a top surface serving as a light exiting surface, a bottom reflective surface and a circumferential surface; and a least one LED unit disposed adjacent to the circumferential surface of the light guide plate. The LED unit comprises at least one LED chip, a light emission section facing the circumferential surface of the light guide plate, and a substrate is disposed on and covering the back surface of the light emission section and electrically connected to the LED chip. A flat reflective member is disposed over a top of the light emission section and extending in parallel with and partly overlapping the light guide plate's top surface adjacent to the circumferential surface which faces the LED unit.