Wavelength Converter Phosphor Distribution for LCD Color Uniformity
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Solution Overview
Problem
In liquid crystal display devices, the wavelength converter's edge region without phosphor in the backlight system can overlap with LEDs, leading to color unevenness due to unconverted light entering the light guide plate, especially with frame-size reduction advancements.
Innovation Solution
The wavelength converter is configured with a higher phosphor concentration at its end portions compared to the center, ensuring efficient wavelength conversion even when the edge region without phosphors overlaps with the LEDs, and a method for manufacturing this converter involves injecting different phosphor solutions with varying concentrations into a container extending along the light entering end surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the wavelength converter extends along the length direction of the light guide plate end surface, then the coverage of wavelength conversion is improved, but the edge region without phosphor overlaps with the LED, causing color unevenness
Solution Approach 1:
The patent applies local quality by creating a non-uniform phosphor distribution within the wavelength converter. Specifically, the phosphor concentration is increased at the end portions of the wavelength converter in the length direction, while maintaining a lower concentration in the center portion. This local variation in phosphor density ensures that regions where light from the LED directly enters the light guide plate still undergo sufficient wavelength conversion, thereby eliminating color unevenness while preserving the extended coverage area.
2Volume of moving object
If frame-size reduction is advanced, then the device compactness is improved, but the position relationship causing color unevenness becomes more prominent
Solution Approach 1:
The patent applies parameter changes by modifying the phosphor concentration distribution parameter along the length direction of the wavelength converter. By increasing the phosphor concentration at the end portions compared to the center portion, the system compensates for the reduced margins available in compacted device designs. This parameter adjustment ensures that even with frame-size reduction and the resulting tighter positioning, adequate wavelength conversion occurs throughout the light guide plate, preventing color unevenness.
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 reduces color unevenness by ensuring that light is efficiently wavelength-converted across the light guide plate, maintaining consistent color tone and improving display quality even with frame-size reduction.
Implementation Method 1
a phosphor configured to wavelength-convert the light from the light source
Data Source
AI summary
A backlight unit includes LEDs a light guide plate, and a wavelength converter. The light guide plate includes a light entering end surface and a light exiting plate surface. The light entering end surface is at least a section of an outer peripheral end surface of the light guide plate. The light exiting plate surface is a plate surface of the light guide plate. The wavelength converter is interposed among the LEDs and the light entering end surface to extend along the length direction of the light entering end surface. The wavelength converter includes phosphors configured to wavelength-convert light. The wavelength converter is configured such that at least any one of end portions in the length direction is formed as a great light emission portion configured to emit a greater amount of wavelength-converted light per unit length in the length direction than that of a center portion.