Linear UV LED Backlight with Continuous Phosphor
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Solution Overview
Problem
Conventional cold cathode fluorescent lamps (CCFLs) used in liquid crystal display devices have low color reproducibility and a significant environmental impact due to mercury usage, while LED-based backlights face challenges with luminance unevenness and manufacturability due to the point-like nature of individual LED chips, requiring additional optical design and diffusion layers.
Innovation Solution
A linear white light source is developed using a base with ultraviolet light-emitting diode chips and a continuous phosphor layer containing red, green, and blue phosphors, which suppresses luminance unevenness and improves manufacturability by mimicking the shape of CCFLs, allowing for easier integration into existing optical designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LED chips are used as light sources, then long life and high reliability are achieved, but luminance unevenness occurs and additional optical components are required
Solution Approach 1:
Multiple LED chips are arranged in a line and their light emission regions are made to overlap, merging their individual light outputs into a unified linear light source that provides uniform illumination without requiring additional diffusion components
Solution Approach 2:
The LED chips are arranged linearly along one dimension with their light emission regions overlapping in the perpendicular dimension, transforming point-like light sources into a continuous linear light source that eliminates luminance unevenness
2Reliability
If LED chips are used as light sources, then high reliability is achieved, but device complexity increases due to additional optical components
Solution Approach 1:
The optical functions of light emission and diffusion are merged into the LED chip arrangement itself, eliminating the need for separate lens-shaped transparent resin layers or diffusion sheets and thereby reducing device complexity
Solution Approach 2:
The need for additional optical components (lens-shaped transparent resin layer, diffusion sheet) is extracted and eliminated by designing the LED chip arrangement to inherently provide uniform light distribution
3Object-generated harmful factors
If CCFLs are replaced by LED chips, then environmental burden is reduced, but shape compatibility with existing optical designs is lost
Solution Approach 1:
The LED chips are arranged linearly to create a long-shaped light source that mimics the form factor of CCFLs, enabling shape compatibility with existing optical designs while using environmentally friendly LED technology
Solution Approach 2:
The linear arrangement of LED chips copies the overall shape and light distribution characteristics of CCFLs, allowing direct replacement in existing applications without requiring new optical design
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 provides improved luminance uniformity and manufacturability, achieving luminance unevenness suppression to 1% or more while maintaining high efficiency, and allows for direct replacement of CCFLs in backlight designs without requiring new optical designs.
Implementation Method 1
a plurality of light emitting diode chips linearly disposed on the base and each generating ultraviolet light
Implementation Method 2
a phosphor layer continuously formed on the base to cover the plurality of light emitting diode chips and including a red light emitting phosphor, a green light emitting phosphor, and a blue light emitting phosphor
Data Source
AI summary
A linear white light source 1 includes a base, a plurality of light emitting diode chips linearly disposed on the base and each generating ultraviolet light having a wavelength of not less than 330 nm nor more than 410 nm, and a phosphor layer continuously formed on the base to cover the plurality of light emitting diode chips and containing a red light emitting phosphor, a green light emitting phosphor, and a blue light emitting phosphor.