Wavelength Conversion Member for Uniform Color Tint
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Solution Overview
Problem
Conventional liquid crystal display devices with edge light backlight units using remote phosphor films experience color irregularity due to uneven wavelength conversion, resulting in differences in color tint between the center and outer peripheral sides.
Innovation Solution
A lighting device with a light guide plate and a wavelength conversion member that has a higher phosphor content per unit area on its outer peripheral side, ensuring efficient wavelength conversion of light emitted from the light source, thereby minimizing color irregularity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a remote phosphor film is used for edge light backlight unit, then the structure is simplified and manufacturing is easier, but color irregularity occurs due to insufficient wavelength conversion on outer peripheral sides
Solution Approach 1:
The wavelength conversion member is designed with non-uniform phosphor distribution: the outer peripheral side portion contains phosphor at a higher concentration than the central portion. This local quality variation ensures that light exiting from the outer peripheral sides of the light guide plate undergoes effective wavelength conversion, matching the color temperature of centrally-exited light, thereby eliminating color irregularity while maintaining the simplified edge light structure.
2Ease of manufacture
If uniform phosphor distribution is used in wavelength conversion member, then manufacturing is simpler, but color tint difference occurs between center and outer peripheral sides
Solution Approach 1:
The wavelength conversion member is designed with non-uniform phosphor distribution: the outer peripheral side portion contains phosphor at a higher concentration than the central portion. This local quality variation ensures that light exiting from the outer peripheral sides of the light guide plate undergoes effective wavelength conversion, matching the color temperature of centrally-exited light, thereby eliminating color irregularity while maintaining the simplified edge light structure.
3Manufacturing precision
If phosphor content is increased on outer peripheral side, then color irregularity is suppressed, but manufacturing complexity increases
Solution Approach 1:
The invention varies the phosphor content parameter across different regions of the wavelength conversion member. Specifically, the phosphor concentration is increased in the outer peripheral side portion compared to the central portion. This parameter change approach achieves uniform color output without requiring complex multi-component systems or additional structural elements, thereby suppressing color irregularity while avoiding excessive manufacturing 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
The solution effectively suppresses color irregularity in the output light, achieving uniform color tint across the display device, enhancing display quality.
Implementation Method 1
containing a phosphor for wavelength-converting the light from the light source
Data Source
AI summary
A backlight unit (lighting device) 12 includes LEDs (light source) 17, a light guide plate 19 including a light entry end surface 19b on at least a part of an outer peripheral end surface and a light output plate surface 19a on a plate surface, and a wavelength conversion sheet (wavelength conversion member) 20 disposed so as to overlap the light output plate surface 19a of the light guide plate 19 and containing a phosphor for wavelength-converting the light from the LEDs 17. Light from the LED 17 enters through the light entry end surface 19b and exits through the light output plate surface 19a. The wavelength conversion sheet 20 includes an increased phosphor portion 27 on at least a part of outer peripheral side portions 20OP thereof and the increased phosphor portion 27 has a phosphor content per unit area that is greater than that in a central portion 20IP.