Backlighting Unit with Phosphor-Converted LED for Wide Color Spectrum
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Solution Overview
Problem
Existing display devices using cold cathode tubes for backlighting are inefficient in providing a wide color spectrum while being simple and cost-effective.
Innovation Solution
A backlighting unit incorporating a blue light-emitting LED and green and red or yellow emitting phosphors, which excite to produce a wide color spectrum, combined with a polarization filter and liquid crystal layer, and color filters to achieve efficient image display with minimal components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If cold cathode tubes are used for backlighting, then the display device can provide illumination, but the color spectrum is limited and the structure is complex
Solution Approach 1:
The patent changes the spectral parameters of the backlight by using a blue LED combined with green and red phosphors instead of traditional cold cathode tubes. This parameter change in the light source enables a wider color spectrum while simplifying the overall backlighting structure.
Solution Approach 2:
The patent employs composite phosphor materials (green phosphor and red phosphor) combined with a blue LED to create a multi-component light source system. This composite approach achieves a broad color spectrum that would be difficult to obtain with a single light source, thereby resolving the contradiction between color quality and structural simplicity.
2Illumination intensity
If multiple light-emitting diodes are provided per pixel to achieve wide color spectrum, then color representation improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent segments the light emission function into three distinct phosphor materials (blue LED and green and red phosphors) that work together in a single integrated backlighting unit. This segmentation allows each component to contribute a specific portion of the color spectrum while maintaining a simple single-LED-per-pixel structure.
Solution Approach 2:
The single blue LED serves multiple functions by exciting both green and red phosphors simultaneously. This multi-functionality allows one LED to generate the entire visible color spectrum through phosphor conversion, eliminating the need for multiple LEDs per pixel while maintaining wide color gamut.
3Ease of manufacture
If traditional backlighting with color filters is used, then the structure is simple, but the color spectrum and image quality are insufficient
Solution Approach 1:
The patent replaces the traditional mechanical color filter system with a photoluminescent conversion system using phosphors. Instead of using filters to select wavelengths, the system uses phosphor materials to convert blue LED light into green and red wavelengths, achieving broader color spectrum with similar structural simplicity.
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
Enables a simple, inexpensive, and effective display with a wide color range by using a single LED per pixel and optimizing phosphor and filter configurations for maximum light output and color representation.
Implementation Method 1
the blue light from the LED excites the green and red emitting phosphors. This enables a particularly good display by means of the screen in a particularly simple and inexpensive manner, since only one light-emitting diode has to be provided for each pixel of the screen and since a particularly wide color spectrum can be displayed
Implementation Method 2
a polarization filter, which is arranged in an emission direction of the backlighting unit and which at least partially covers the backlighting unit
Implementation Method 3
a liquid crystal layer, which is arranged on the side of the polarization filter which is remote from the backlighting unit
Implementation Method 4
a filter arrangement, which has at least one color filter and which is arranged on the side of the liquid crystal layer facing away from the backlighting unit
Data Source
Figure 1~2
Figure 3
AI summary
Disclosed is a display device, especially a screen unit (6) of a screen (4), comprising a backlighting unit (8) for backlighting the screen (4), a polarizing filter (10) that is arranged in an emitting direction of the backlighting unit (8) and at least partially covers the backlighting unit (8), a liquid crystal layer (14) that is arranged on the side of the polarizing filter (10) facing away from the backlighting unit (8), and a filter arrangement (16) that encompasses at least one color filter and is arranged on the side of the liquid crystal layer (14) facing away from the backlighting unit (8). The backlighting unit (8) comprises a blue light emitting diode (22), downstream of which at least two different phosphors are arranged that absorb the blue light of the light emitting diode (22) and re-emit light which has different colors and mixes with the blue light of the light emitting diode (22) to generate white light.