Phosphor-Based LED Sign for Color Versatility and Daylight Saturation
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Solution Overview
Problem
Conventional light emitting signs suffer from limited color options due to the need for diverse color sources, poor color saturation in daylight conditions, and increased cost, as well as inefficiencies in brightness and uniformity.
Innovation Solution
A light emitting sign utilizing a phosphor material excited by a single low-cost radiation source, such as a blue LED, to generate a selected color, combined with a reflective color filter for improved color performance and efficiency, eliminating the need for multiple color sources and filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple colored light sources are used to achieve full color range, then color variety is improved, but device complexity and cost increase
Solution Approach 1:
A single ultraviolet or blue LED light source performs multiple functions by exciting different phosphor materials to generate various colors. The system uses one universal excitation source that can produce red, green, blue, yellow and other colors through phosphor conversion, eliminating the need for multiple dedicated colored light sources.
Solution Approach 2:
The invention changes the parameter of light wavelength through phosphor materials. By selecting different phosphor materials with specific emission characteristics, the same ultraviolet or blue LED excitation source can generate light across the visible spectrum, achieving color variety through material parameter selection rather than using multiple light sources.
2Illumination intensity
If transparent color filters are used to generate colored light, then color performance at night is improved, but color saturation in daylight deteriorates
Solution Approach 1:
Instead of using transparent filters that absorb unwanted colors (subtractive method), the invention uses phosphor materials that emit specific colors when excited (additive method). This inversion from absorption to emission provides superior color saturation because the phosphor generates only the desired color wavelengths rather than filtering out others from white light.
Solution Approach 2:
The invention employs phosphor materials that change color based on their emission characteristics when excited by ultraviolet or blue light. Different phosphor materials emit different colors (red, green, blue, yellow), providing adaptability for various color requirements while maintaining high saturation in both nighttime and daylight conditions.
3Illumination intensity
If brightness is increased to improve visibility, then illumination intensity is improved, but color saturation deteriorates due to white backlight bleeding through
Solution Approach 1:
The invention extracts only the necessary color wavelengths by using phosphor materials that emit specific colors when excited. Rather than using a broad-spectrum white backlight that requires filtering, the system generates only the required color wavelengths directly through phosphor emission, eliminating the problem of white light bleeding through and compromising color saturation.
4Ease of manufacture
If conventional backlight systems are used, then ease of manufacture is improved, but light uniformity and brightness distribution worsen
Solution Approach 1:
The invention applies phosphor materials directly to the light guide plate surface at specific locations where color emission is needed. This localized application allows for precise control of light emission characteristics and uniformity across different areas of the display, while maintaining ease of manufacture through direct phosphor coating or lamination techniques.
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 solution allows for a wide range of colors to be generated with a single excitation source, enhancing color saturation and uniformity, reducing costs, and maintaining performance in both nighttime and daylight conditions.
Implementation Method 1
a light emitting display surface including at least one phosphor; and at least one radiation source operable to generate and radiate excitation energy of a selected wavelength range, the source being configured to irradiate the display surface with excitation energy such that the phosphor emits radiation of a selected color
Data Source
AI summary
A light emitting sign comprising a light box housing a plurality of blue LEDs operable to generate blue excitation light and a light emitting display surface overlaying the light box opening. The light emitting display surface comprises a light transmissive substrate configured as a light transmissive window such that light generated by the sign is emitted from the substrate and a phosphor overlaying at least a portion of one face of the substrate. The phosphor is configured to absorb at least a portion of the blue light generated by the LEDs and, in response, to emit light of a selected color.