Direct-Lit Backlight Uniformity via Localized Color Conversion
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Solution Overview
Problem
Direct-lit backlight units in electronic devices can be bulky and produce non-uniform backlight illumination if not designed properly, leading to suboptimal display performance.
Innovation Solution
The implementation of a direct-lit backlight unit with a pixel array illuminated by an array of light-emitting diodes (LEDs) on a printed circuit board, incorporating multiple light spreading layers, a color conversion layer, brightness enhancement films, and a diffusion film, along with reflective layers and adhesive patches to ensure uniform illumination and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a direct-lit backlight unit is implemented, then the display can achieve simpler structure and better uniformity control, but the initial design may result in bulky size and non-uniform illumination
Solution Approach 1:
The patent applies local quality by making the color conversion layer non-uniform, with varying phosphor concentrations and thicknesses in different regions to compensate for the inherent non-uniformity of direct-lit LED backlighting. This creates locally optimized optical properties that result in globally uniform illumination.
Solution Approach 2:
The patent changes optical parameters by varying the refractive index, thickness, and material composition of the color conversion layer and optical films to control light distribution and achieve uniform illumination from a direct-lit backlight configuration.
2Illumination intensity
If multiple optical layers are added to improve uniformity, then illumination uniformity improves, but the overall display thickness increases
Solution Approach 1:
The patent merges the color conversion function with the light diffusion function into a single integrated color conversion layer, eliminating the need for separate diffusion layers and reducing overall thickness while maintaining uniformity.
Solution Approach 2:
The color conversion layer performs multiple functions simultaneously: converting LED light to the desired color spectrum, diffusing light to eliminate hotspots, and compensating for illumination non-uniformity through its non-uniform structure.
3Illumination intensity
If reflective layers are added in the notch region, then illumination uniformity near the notch improves, but the device complexity increases
Solution Approach 1:
The patent applies local quality by adding reflective layers specifically in the notch region where illumination uniformity is compromised, rather than throughout the entire display. This localized approach improves uniformity where needed without unnecessarily increasing overall complexity.
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 the uniformity and brightness of the backlight illumination, mitigates electrostatic discharge, and improves the mechanical strength of the display, resulting in a more reliable and visually consistent electronic device.
Implementation Method 1
Direct-lit backlight units have arrays of light-emitting diodes that emit light vertically through the display
Implementation Method 2
The color conversion layer may have a property that varies as a function of position. The property may be the thickness of a phosphor layer in the color conversion layer
Implementation Method 3
the concentration of red quantum dots in the color conversion layer, the concentration of green quantum dots in the color conversion layer
Implementation Method 4
The light guide plate then distributes the emitted light laterally across the display to serve as backlight illumination
Implementation Method 5
A diffusion film may be formed over the brightness enhancement films
Data Source
AI summary
A display may have a pixel array such as a liquid crystal pixel array. The pixel array may be illuminated with backlight illumination from a direct-lit backlight unit. The backlight unit may include an array of light-emitting diodes (LEDs) on a printed circuit board. The display may have a notch to accommodate an input-output component. Reflective layers may be included in the notch. The backlight may include a color conversion layer with a property that varies as a function of position. The light-emitting diodes may be covered by a slab of encapsulant with recesses in an upper surface.