Side-Emitting LED Frame Layout for Uniform Backlight Brightness
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Solution Overview
Problem
Existing light emitting diode (LED) devices used as backlights in displays suffer from uneven brightness due to variations in light distribution.
Innovation Solution
A light emitting diode device with a low-reflectivity frame and a concave portion, combined with an LED die having a side-emitting surface with greater luminous intensity than the top-emitting surface, expands the light emitting angle to improve brightness uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional LED devices with high reflectivity frames are used, then light extraction efficiency is improved, but brightness uniformity deteriorates due to concentrated light distribution
Solution Approach 1:
The patent changes the reflectivity parameter of the frame from conventional high reflectivity (typically >80%) to low reflectivity (20%-40%), which fundamentally alters the light distribution pattern. This parameter change reduces concentrated light reflection while maintaining sufficient light extraction, thereby improving brightness uniformity across the display panel.
Solution Approach 2:
The patent introduces a concave portion at the center of the frame with different optical properties compared to the flat peripheral region. This local structural differentiation creates zones with varying light reflection and diffusion characteristics, enabling the central area to distribute light more uniformly while the periphery maintains structural integrity and light extraction function.
2Ease of manufacture
If LED die with dominant top-emitting surface is used, then manufacturing simplicity is maintained, but light emitting angle is limited causing brightness non-uniformity
Solution Approach 1:
The patent utilizes the asymmetric luminous intensity distribution inherent in side-emitting LED dies, where the side surface emits light with higher intensity and wider angle compared to the top surface. By positioning the LED die with its side surface facing the display panel, the asymmetric emission pattern is optimized to achieve broader light coverage and improved brightness uniformity.
Solution Approach 2:
The patent transitions from relying primarily on top-emission (vertical dimension) to utilizing side-emission (horizontal dimension) as the dominant light output path. This dimensional shift in light emission allows light to be distributed across a wider angular range, effectively expanding the light emitting angle from typical 120 degrees to over 140 degrees.
3Use of energy by moving object
If frame with high light reflectivity is used, then light extraction is enhanced, but light distribution becomes concentrated causing uneven brightness
Solution Approach 1:
The patent converts the potentially harmful effect of light concentration (caused by high reflectivity) into a beneficial diffuse distribution pattern. By using low reflectivity materials in the concave frame structure, the frame absorbs and scatters concentrated light rays, transforming them into diffusely distributed light that illuminates the display panel more uniformly, thereby converting the harm of concentration into the benefit of uniform distribution.
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 effectively enhances the light emitting angle by 140-160 degrees, reducing top luminous intensity and improving the uneven brightness of backlight modules in displays.
Implementation Method 1
The frame has a light reflectivity ranging from 20% to 40%
Implementation Method 2
The LED die has a side-emitting surface and a top-emitting surface, the side-emitting surface has a luminous intensity greater than that of the top-emitting surface
Data Source
AI summary
A light emitting diode device includes a substrate, a frame, an LED die and a transparent layer. The frame is located on the substrate. The frame and the substrate collectively define a concave portion. The frame has a light reflectivity ranging from 20% to 40%. The LED die is located on the substrate and within the concave portion. The transparent layer is filled into the concave portion and covering the LED die, wherein the LED die has a side-emitting surface and a top-emitting surface, the side-emitting surface has a luminous intensity greater than that of the top-emitting surface.