LED Display Sub-Pixel Phosphor Tuning for Color Accuracy
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Solution Overview
Problem
Display devices using LED sub-pixels face challenges in achieving target color coordinates due to variations in optical characteristics such as peak wavelength and luminance of LED chips, making it difficult to implement accurate color representation.
Innovation Solution
The implementation of a semiconductor device with red, green, and blue sub-pixels, each comprising a light-emitting diode and a transmissive material with a tuning phosphor that adjusts the light emission to achieve secondary peak intensities, allowing for improved color characteristics and color coordination in LED display panels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If LED chips are used as sub-pixels in display devices, then compact size and high luminance are achieved, but color coordinate accuracy deteriorates due to variations in optical characteristics of LED chips
Solution Approach 1:
The patent applies parameter changes by adjusting the peak wavelengths of LED chips through selection of different chip types (e.g., 450nm, 460nm, 470nm blue chips) and modifying the composition and characteristics of phosphor materials. By changing these physical parameters, the invention compensates for variations in LED optical characteristics to achieve accurate color coordinates (e.g., sRGB standard) while maintaining high luminance output.
Solution Approach 2:
The patent uses composite materials by combining multiple phosphors with different emission characteristics (e.g., yellow phosphor with red phosphor for white LED, or green phosphor with red phosphor for cyan LED). This composite approach allows tuning of the overall emission spectrum to achieve target color coordinates despite variations in the base LED chip characteristics, thereby resolving the contradiction between high luminance and color accuracy.
2Manufacturing precision
If multiple LED chips with different peak wavelengths are used to achieve target color coordinates, then color accuracy is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the color generation function into distinct components: blue LED chip for blue sub-pixel, cyan LED chip for green sub-pixel, and magenta LED chip for red sub-pixel. Each sub-pixel is independently optimized with specific LED-phosphor combinations, allowing simplified individual design while achieving overall color accuracy when assembled into the complete display device.
Solution Approach 2:
The patent implements local quality by optimizing each sub-pixel region with specific LED chip types and phosphor compositions tailored to that color channel. For example, the blue sub-pixel uses 450-470nm blue LEDs with yellow phosphor, while the green sub-pixel uses cyan LEDs with green phosphor. This localized optimization simplifies the overall design compared to using multiple wavelengths in each sub-pixel, as each region has a dedicated, simplified configuration.
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 approach enables the production of LED display panels with enhanced color accuracy and optical efficiency, allowing for compact, high-luminance displays with adjustable aspect ratios and various forms, while effectively tuning color coordinates to match target values.
Implementation Method 1
a light emitting diode and a transmissive material positioned to receive light from the corresponding light emitting diode
Implementation Method 2
the tuning phosphor having a material property to absorb light emitted by the light emitting diode of the first sub-pixel and emit light that does not have a wavelength of the absorbed light
Data Source
AI summary
A pixel of a light emitting diode module, display panel or other device, may comprise different colored sub-pixels, where one of the sub-pixels comprises a wavelength converting material, such as phosphor, to convert light emitted from an associated light emitting diode of that sub-pixel into a color other than the main color of light emitted from that sub-pixel. The wavelength converting material may have an amount selected to tune the color coordinates of the pixel. The amount of wavelength converting material may be determined in response to measuring the intensity of the spectrum of light emitted by the light emitting diode of the sub-pixel, or similarly manufactured sub-pixels, on which the wavelength converting material is to be formed. Methods of manufacturing the same are also disclosed.