Light Source Module Segmented Phosphors for Reflective Display Color Shift
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Solution Overview
Problem
Reflective display apparatuses experience color shifts when using a light emitting diode (LED) light source module due to differences in light emission when the module is on or off, especially in low ambient light conditions, affecting image clarity.
Innovation Solution
A light source module incorporating a light guide plate and a light source with a blue light emitting device, a first wavelength conversion unit converting blue light to a first light in the range of 480 nm to 650 nm, and a second wavelength conversion unit converting blue light to a second light of a different wavelength, combining to produce white light with a color temperature range of 5000 K to 7000 K, thereby reducing color shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a blue light emitting device with yellow phosphor is used to produce white light, then the light source module can provide sufficient illumination, but a significant color shift occurs between the light source being on and off
Solution Approach 1:
The single yellow phosphor layer is segmented into multiple wavelength conversion units with different phosphors (first wavelength conversion unit with cyan phosphor, second wavelength conversion unit with red phosphor). This segmentation allows independent optimization of different spectral components to achieve consistent color perception under both lit and unlit conditions.
Solution Approach 2:
The patent uses composite phosphor materials including cyan phosphor, green phosphor, yellow phosphor, and red phosphor in different wavelength conversion units. These composite materials work together to convert blue light into a balanced spectrum that maintains color consistency, reducing the color shift between on and off states.
2Stability of the object's composition
If multiple wavelength conversion units are added to reduce color shift, then color consistency improves, but device complexity increases
Solution Approach 1:
Multiple wavelength conversion units are merged into a single integrated light source module structure. The first and second wavelength conversion units are positioned adjacent to the blue light emitting device, with their combined output forming the final white light. This merging approach achieves color consistency without requiring separate modular components.
Solution Approach 2:
The patent addresses the color consistency problem by adding a spectral dimension rather than increasing mechanical complexity. Instead of using multiple independent light sources, it converts the blue light from a single LED into multiple wavelength components through phosphor conversion, achieving full-spectrum white light with consistent color perception.
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 compensates for excessive reflectance differences in reflective display panels, reducing color shifts between the light source module being on and off, ensuring consistent color representation.
Implementation Method 1
When the blue light is incident to the first wavelength conversion unit, the blue light is converted into a first light
Implementation Method 2
When the blue light is incident to the second wavelength conversion unit, the blue light is converted to a second light
Implementation Method 3
The blue light, the first light and the second light combine to produce a white light
Data Source
AI summary
A light source module includes a light guide plate including a light entrance surface and a light source adjacent to the light entrance surface. The light source includes a light emitting device to emit a blue light, a first wavelength conversion unit on the light emitting device and a second wavelength conversion unit on the light emitting unit. When the blue light is incident to the first wavelength conversion unit, the blue light is converted into a first light. The first light has a wavelength in a range from 480 nm to 650 nm. When the blue light is incident to the second wavelength conversion unit, the blue light is converted to a second light. The second light has a wavelength different from the wavelength of the first light. The blue light, the first light and the second light combine to produce a white light.