Projection Display Light Source with Laser-Phosphor Color Compensation
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Solution Overview
Problem
Existing light emitting devices for projection systems face low efficiency and brightness issues with red light, as well as color coordinate deviations from standard gamuts, leading to reduced image quality, particularly in applications requiring high brightness and saturation.
Innovation Solution
A projection system that combines laser lights with fluorescent lights using time-based light combination, where excitation and compensation lights alternately illuminate segments of a wavelength conversion device to enhance efficiency and color coordinates, utilizing both transmission and reflection regions to minimize light loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If orange or yellow phosphor materials are used to generate red light, then the device complexity is reduced, but the light utilization efficiency and brightness of red light are low
Solution Approach 1:
The patent segments the red light generation process into two parts: blue laser light generates orange fluorescent light through phosphor, and red laser light is superimposed to compensate for the spectral gap. This segmentation allows each light source to perform its optimal function while achieving high overall efficiency.
Solution Approach 2:
The patent combines orange fluorescent light and red laser light into a unified red light output through optical superposition. This merging of different light generation mechanisms (fluorescence and direct laser) creates a composite light source that achieves both high brightness and spectral accuracy.
2Manufacturing precision
If filters are added to correct red light color coordinates, then the color coordinates meet standard gamut requirements, but the brightness and light utilization efficiency of red light are further reduced
Solution Approach 1:
The patent applies preliminary action by pre-adjusting the spectral composition through the combination of orange phosphor conversion and red laser superposition before the light reaches the projection optics. This preliminary spectral engineering eliminates the need for subsequent filtering, preserving maximum brightness while achieving accurate color coordinates.
3Use of energy by moving object
If green fluorescent light is used, then the light conversion efficiency is high, but the spectral range is broad causing low color saturation
Solution Approach 1:
The patent extracts the problematic long-wavelength portion of the green fluorescent spectrum using a bandpass filter, retaining only the useful spectral components for high saturation green light while maintaining the high conversion efficiency of fluorescent materials.
4Use of energy by moving object
If blue laser light is used to excite orange phosphor, then the light emission efficiency is high, but the red light brightness and saturation are insufficient
Solution Approach 1:
The patent introduces orange phosphor as an intermediary that converts blue laser light to orange fluorescent light, which then serves as the base for red light generation. This intermediary enables efficient energy transfer while creating the optimal spectral foundation for high-brightness red light output.
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
Improves the utilization efficiency and brightness of both laser and fluorescent lights, reducing costs and enhancing image quality by aligning color coordinates with REC.709 and DCI standards.
Implementation Method 1
The green light is obtained by exciting a green phosphor material with the blue light, and the red light is obtained by exciting an orange or yellow phosphor material with the blue light
Implementation Method 2
The blue light is obtained using scattering power to remove the coherency of the laser light
Data Source
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Figure 5~6a
AI summary
A light emitting device and a projection display apparatus. The light emitting device comprises: an excitation light source (11), used for emitting excitation light; a compensation light source (12), used for emitting compensation light having a spectral range different from that of the excitation light; and a wavelength conversion device (13), disposed in a transmission path of the excitation light and the compensation light and used for outputting sequential light under alternate irradiation of the excitation light source (11) and the compensation light source (12), the sequential light comprising at least one type of excited light and the compensation light. The compensation light has spectral overlap with at least one type of excited light in the at least one type of excited light, so as to greatly improve the brightness of the light emitting device and the utilization efficiency of light in the light emitting device.