Laser-Phosphor Projector Green Phosphor Spectral Control
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Solution Overview
Problem
Current laser-phosphor projectors face significant brightness reduction and color gamut issues due to the limitations of yellow phosphors, particularly in achieving DCI compliance, with excessive green light and insufficient red light leading to substantial light losses and color point deviations.
Innovation Solution
The implementation of a light projection system using a combination of blue lasers and a green phosphor with specific spectral characteristics, along with a red laser, to optimize the color gamut and reduce light losses, featuring a wavelength conversion element with a centroid wavelength less than 560 nm and a Green-Red transition zone content (GRTZC) of less than 16%, and the use of variable waveband reduction filters to adjust the white point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If yellow phosphor is used in laser-phosphor projectors, then the device complexity is reduced, but brightness is significantly reduced and color gamut compliance (DCI) deteriorates
Solution Approach 1:
The patent changes the spectral parameters of the phosphor material from yellow phosphor (broad spectrum with excessive green) to green phosphor with centroid wavelength less than 560 nm and controlled Green-Red transition zone content. This parameter change in the phosphor material enables DCI compliance while maintaining high brightness and reducing the need for complex optical filtering.
2Ease of manufacture
If yellow phosphor is used in laser-phosphor projectors, then the ease of manufacture is improved, but color gamut compliance (DCI) and color accuracy deteriorate
Solution Approach 1:
The patent specifies precise spectral parameters for the green phosphor (centroid wavelength less than 560 nm, Green-Red transition zone content less than 16%) to ensure DCI compliance. This parameter-controlled approach maintains manufacturing simplicity while achieving precise color gamut compliance that yellow phosphor cannot provide.
3Device complexity
If yellow phosphor is used in laser-phosphor projectors, then the device complexity is reduced, but color accuracy and white point control deteriorate
Solution Approach 1:
The patent changes from yellow phosphor with uncontrolled spectral distribution to green phosphor with controlled centroid wavelength and transition zone content. This enables precise control of color accuracy and white point (D65 compliance) without adding device complexity, as the phosphor itself provides the necessary spectral characteristics.
4Manufacturing precision
If green phosphor with specific spectral characteristics is used, then DCI compliance and color accuracy are improved, but the device complexity increases
Solution Approach 1:
The patent achieves DCI compliance through parameter control of the green phosphor material itself (centroid wavelength, transition zone content) rather than through complex optical systems. The simplified optical path without yellow phosphor filtering actually reduces device complexity while maintaining precise color accuracy.
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 approach minimizes light losses and achieves DCI compliance with improved color performance, providing a more compact, cost-effective projector design that maintains high brightness and color accuracy.
Implementation Method 1
a wavelength conversion element for emitting light at a plurality of wavelengths after absorption of a light beam at an excitation wavelength
Implementation Method 2
a variable waveband reduction filter... movement of said variable waveband reduction filter... results in a change of the transmitted waveband of the white beam
Data Source
AI summary
A light projection system for generating an image with three primary colors, each primary color being respectively defined by a first, second and third wavebands. The system includes a first blue laser source emitting a first beam in a fourth waveband, the first blue laser source having a first laser driver, a second blue laser source emitting a second beam having a central wavelength and a fifth waveband, the second blue laser source having a second laser driver, a substrate having a wavelength conversion element for emitting light at a plurality of wavelengths after absorption of a light beam at an excitation wavelength within a fifth waveband of the second blue laser source and a beam combiner for combining the combined first beam and the converted beam, which combination results in a white beam. Dichroic losses can be reduced by using a green phosphor together with red laser assistance.