Backlight Unit Using Single Blue LED Chip for Color Dimming
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Solution Overview
Problem
Liquid crystal displays (LCDs) face increased manufacturing costs and color balance difficulties due to differences in color characteristics between red, green, and blue light emitting diodes, especially when employing dimming technology for high-definition displays.
Innovation Solution
A display apparatus with a backlight unit utilizing two light sources, both incorporating the same light emitting diode chip, allows for color dimming on a desired color, reducing manufacturing costs and preventing color characteristic differences over time, by using a first light source emitting white light and a second light source emitting cyan light, both driven by a single blue LED chip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If red, green, and blue light emitting diodes are employed for dimming technology, then color dimming control is achieved, but manufacturing cost increases and color balance becomes difficult to maintain
Solution Approach 1:
The patent merges multiple light sources by using the same blue LED chip for both the first light source (with yellow phosphor for white light) and the second light source (with cyan phosphor for cyan light). This consolidation reduces manufacturing complexity and cost while maintaining the capability for color-specific dimming control through selective activation of different light source combinations.
Solution Approach 2:
The blue LED chip serves multiple functions by acting as the excitation source for both the yellow phosphor (producing white light) and the cyan phosphor (producing cyan light). This multi-functional design eliminates the need for separate red, green, and blue LED assemblies, simplifying manufacturing while enabling color dimming through differential control of the two light sources.
2Ease of operation
If red, green, and blue light emitting diodes are employed for dimming technology, then color dimming control is achieved, but color balance becomes difficult to maintain due to differences in color characteristics
Solution Approach 1:
The patent merges multiple light sources by using the same blue LED chip for both the first light source (with yellow phosphor for white light) and the second light source (with cyan phosphor for cyan light). This consolidation reduces manufacturing complexity and cost while maintaining the capability for color-specific dimming control through selective activation of different light source combinations.
Solution Approach 2:
The patent uses the same blue LED chip for both light sources, ensuring homogeneous excitation characteristics and minimizing color variation over time. This homogeneity in the light-generating component eliminates the color balance issues that arise from using different red, green, and blue LED chips with varying characteristics.
3Illumination intensity
If different light emitting diode chips are used for different colors, then color characteristics are achieved, but differences in color characteristics occur over time
Solution Approach 1:
The patent uses the same blue LED chip for both light sources, ensuring homogeneous excitation characteristics and minimizing color variation over time. This homogeneity in the light-generating component eliminates the color balance issues that arise from using different red, green, and blue LED chips with varying characteristics.
Solution Approach 2:
The patent changes the optical parameters by using different phosphor materials (yellow vs. cyan) excited by the same blue LED chip, rather than changing the LED chip itself. This parameter change in the phosphor layer allows for stable, consistent color characteristics over time while still achieving the desired color output.
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 expands the color reproduction range, maintains color balance, and reduces manufacturing costs by using the same blue LED chip for both light sources, preventing variations in color characteristics over time.
Implementation Method 1
a blue light emitting diode chip which emits blue light
Implementation Method 2
a first phosphor material disposed around the blue light emitting diode chip and emitting first light by being excited by the blue light
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A display apparatus includes a backlight unit including a first light source emitting a first light having at least two peak wavelengths and a second light source emitting a second light having a peak wavelength different from the two peak wavelengths, and a display panel receiving the first and second lights to display an image corresponding to an input image data, and a light source driver which analyzes a color information of predetermined dimming areas on the basis of the input image data and controls a contribution of the first and second light sources with respect to a target brightness of each of the predetermined dimming areas in accordance with the color information.