Liquid Crystal Display Illumination with Phosphor-Converted Blue Light
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Solution Overview
Problem
Liquid crystal display devices with pseudo-white LEDs face challenges in achieving high color purity and panel transmittance due to the broad emission spectrum of pseudo-white LEDs, leading to decreased transmittance and increased light leakage when viewed from angles, making it difficult to comply with standards like sRGB and Adobe RGB.
Innovation Solution
A liquid crystal display device configuration that includes a blue light-emitting element, green and red phosphors, and colored blue color filters with specific spectral characteristics, optimizing the emission and transmission spectra to enhance color separation and reduce light leakage, allowing for higher panel transmittance and compliance with high color purity standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the spectral transmission characteristics of the color filters are strictly controlled to achieve adequate color separation, then color purity is improved, but the transmittance of the color filters decreases
Solution Approach 1:
The patent changes the spectral parameters of the illumination device by using specific phosphors with defined emission characteristics (green phosphor with peak at 530-560nm, red phosphor with peak at 610-650nm) and controls the chromaticity coordinates of white light (x: 0.28-0.32, y: 0.28-0.32). This allows the color filters to achieve adequate color separation while maintaining higher transmittance in their passbands, resolving the contradiction between color purity and energy loss.
Solution Approach 2:
The patent uses a composite illumination system combining blue light-emitting elements with multiple phosphors (green and red) to create white light with specific spectral characteristics. This composite approach enables better matching with the color filter transmission characteristics, achieving both good color separation and maintained transmittance.
2Manufacturing precision
If the thickness of the color filters is increased to improve color separation, then color purity is improved, but light leakage from adjacent pixels increases
Solution Approach 1:
The patent optimizes the thickness parameter of the color filters by combining it with specific spectral transmission characteristics that are tailored to the illumination device's emission spectrum. This allows achieving adequate color separation with optimized filter thickness, preventing excessive light leakage from adjacent pixels while maintaining color purity.
3Manufacturing precision
If the area of the light shielding layer is increased to prevent light leakage, then color purity is improved, but the pixel aperture ratio decreases
Solution Approach 1:
The patent optimizes the area parameter of the light shielding layer by combining it with color filters that have specific spectral transmission characteristics. This allows achieving adequate color separation and preventing light leakage with optimized shielding layer area, maintaining higher pixel aperture ratios while ensuring color purity.
4Use of energy by moving object
If pseudo-white LEDs with broad emission spectrum are used, then luminous efficacy and cost are improved, but panel transmittance and color reproduction deteriorate
Solution Approach 1:
The patent modifies the spectral parameters of the illumination device by using specific phosphors with defined emission characteristics (green phosphor with peak at 530-560nm, red phosphor with peak at 610-650nm) and controls the chromaticity coordinates of white light. This creates a more targeted spectrum that better matches the color filter transmission characteristics, reducing energy loss in the panel while maintaining high luminous efficacy and improving color reproduction to meet standards like sRGB and Adobe RGB.
Solution Approach 2:
The patent replaces conventional pseudo-white LEDs with a composite illumination system combining blue light-emitting elements with multiple phosphors (green and red). This composite approach creates white light with optimized spectral characteristics that improve both panel transmittance and color reproduction performance while maintaining cost-effectiveness.
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 achieves excellent color reproduction and high panel transmittance, improving brightness and reducing power consumption while minimizing light leakage from adjacent pixels, even when viewed from angles, thus enhancing display quality and compliance with stringent color standards.
Implementation Method 1
a green phosphor that absorbs a portion of the blue light emitted from the light-emitting element and then emits green light
Implementation Method 2
a red phosphor that absorbs a portion of the blue light emitted from the light-emitting element and then emits red light
Implementation Method 3
the blue color filter is made of a colored material that contains a dye
Data Source
AI summary
A liquid crystal display device includes: a liquid crystal display panel that includes red color filters, green color filters, and blue color filters; and an illumination device that illuminates the liquid crystal display panel with white light. The illumination device includes light-emitting elements that emit blue light, a green phosphor that absorbs a portion of the blue light emitted from the light-emitting elements and then emits green light, and a red phosphor that absorbs a portion of the blue light emitted from the light-emitting elements and then emits red light. The blue color filters are made of a colored material that contains a dye, and the chromaticity values x and y of the white light emitted from the illumination device satisfy the relationships 0.24<x and 0.24<y.