Static Green Primary Color Reduction Filter for Laser Projection
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Solution Overview
Problem
Laser phosphor projection systems face significant light and contrast ratio losses due to the excess of blue and green light, leading to reduced image quality and increased energy load on light modulators, as they attempt to match the DCI white point, and suffer from white color point shifts with laser aging.
Innovation Solution
An optical assembly that includes a blue laser source with a static wavelength conversion element and a combination of yellow notch and green waveband reduction filters to adjust the spectral distribution, ensuring the native white point aligns with the target DCI white point without compromising contrast or bit depth, using a single blue laser source for both primary color generation and excitation, and controlling the intensity of blue laser beams independently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electronic correction is applied to match DCI white point, then color accuracy is improved, but contrast ratio deteriorates
Solution Approach 1:
The patent applies preliminary spectral filtering to the light source before it reaches the modulators. By pre-adjusting the spectrum to match DCI standards, the system eliminates the need for post-processing electronic correction, thereby maintaining both color accuracy and contrast ratio. The filters are positioned in the optical path before the modulators to prevent excess energy from reaching them.
Solution Approach 2:
The patent extracts and removes the excess blue and green spectral components from the light source using targeted filters. This extraction prevents these excess wavelengths from contributing to the white point mismatch, eliminating the need for electronic correction while preserving the useful spectral content for high contrast ratio projection.
2Measurement precision
If electronic correction is applied to match DCI white point, then color accuracy is improved, but bit depth deteriorates
Solution Approach 1:
The system performs preliminary spectral matching using optical filters before the light reaches the modulators. This pre-correction ensures that the native white point already matches DCI standards, allowing the modulators to operate with their full dynamic range and preserve maximum bit depth without the constraints of electronic correction.
3Measurement precision
If light modulation devices are used for electronic correction, then color accuracy is improved, but device complexity increases
Solution Approach 1:
The patent removes the need for electronic correction by extracting and eliminating the spectral mismatch at its source. Simple optical filters are used to pre-shape the spectrum, replacing the complex electronic correction process that would otherwise require additional light modulation devices and control systems.
Solution Approach 2:
The patent replaces the electronic correction mechanism (software-based color correction in light modulation devices) with a physical/optical solution (spectral filters). This substitution eliminates the need for complex electronic processing while achieving the same color accuracy goal.
4Temperature
If light not used on screen illuminates the modulator, then cooling requirements increase, but energy waste increases
Solution Approach 1:
The patent extracts and removes the excess spectral content (particularly blue and green wavelengths) before it reaches the modulators. This prevents the modulators from absorbing unnecessary energy that would require cooling, thereby eliminating waste heat generation without sacrificing the useful light needed for projection.
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 maintains high image quality by minimizing light losses and heat generation, while ensuring the projector's white point stability across the lifespan of the lasers, thereby improving contrast ratio and bit depth without excessive cooling requirements.
Implementation Method 1
a single blue laser source (320) for simultaneously generating the blue primary color on screen and for exciting a phosphor
Implementation Method 2
a notch filter is used to obtain the color gamut as described in the DCI standard
Implementation Method 3
a combination of yellow notch and green waveband reduction filters to adjust the spectral distribution
Data Source
Figure 1~2a
Figure 2b~3
Figure 4~5a
AI summary
A projection system for generating an image with three primary colors, comprising a first and second blue laser beam (325, 335), a wavelength conversion element (340) for converting said second blue beam (335) into a converted beam (345) having a waveband comprising at least the second and third wavebands, a beam combiner (360) for combining the first beam (325) and the converted beam (345), which combination results in a white beam (365), a notch filter (370) placed in the optical path of the white beam (365) to form a modified white beam (375) comprising at least the first, second and third wavebands provided to an imaging module (380), wherein a static waveband reduction filter (371) is further provided for changing the wavelength of transmitted second waveband of the white beam (365), such as to adjust a projector white point shift.