Curved Dichroic Mirror for Uniform Fluorescence in Projection Displays
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Solution Overview
Problem
In projection type display apparatuses, the nonuniformity of transmission and reflection characteristics in dichroic mirrors due to varying incident angles of fluorescence leads to color irregularity and reduced light amount, increasing costs when trying to address these issues.
Innovation Solution
A light source device featuring a surface-curved dichroic mirror with a convexly curved surface that reflects excitation light and allows fluorescence to pass through, along with a converging lens positioned between the dichroic mirror and the phosphor, which reduces the difference in incident angles and maintains uniform transmission and reflection characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flat plate dichroic mirror is used to separate excitation light and fluorescence, then the optical path can be effectively separated, but the incident angle of fluorescence varies with position on the mirror causing nonuniform transmission characteristics, color irregularity, and light amount reduction
Solution Approach 1:
The patent applies a curved surface design to the dichroic mirror instead of a flat plate. The curved surface is specifically designed to match the divergent angle of fluorescence from the phosphor, ensuring that fluorescence rays incident on different positions of the mirror maintain a substantially constant incident angle. This curvature compensates for the angular divergence of fluorescence, uniformizing the transmission characteristics across the entire mirror surface and eliminating color irregularity while maintaining effective optical path separation.
2Device complexity
If the same point on the phosphor is continuously illuminated with excitation light, then the light source structure can be simplified, but temperature increases and light-emitting efficiency decreases, and material deterioration may occur
Solution Approach 1:
The patent introduces a rotating mechanism that causes the phosphor to rotate during illumination. This dynamic operation ensures that the excitation light continuously illuminates different points on the phosphor surface rather than the same point, distributing the thermal load and preventing localized overheating. This maintains light-emitting efficiency and prevents material deterioration while the rotation mechanism is designed to be compact and integrated into the light source structure.
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 configuration significantly reduces the difference in incident angles, minimizing light loss and ensuring uniform illumination, thereby enhancing image quality and reducing costs by maintaining high-efficiency light usage.
Implementation Method 1
A phosphor is excited by output light of the semiconductor laser, and light that is wavelength-converted by the phosphor is used as a light source
Implementation Method 2
a dichroic mirror in the shape of a flat plate is mostly positioned between the excitation light source and the phosphor plate
Implementation Method 3
a converting lens, illuminates a phosphor plate that rotates with the output light
Data Source
AI summary
A light source device for a projection display apparatus includes a phosphor, an excitation light source, a surface-curved dichroic mirror having a curved surface in which a side on which excitation light is incident is convexly curved, and a converging lens between the surface-curved dichroic mirror and the phosphor. The excitation light source is configured to output the excitation light for exciting the phosphor. The surface-curved dichroic mirror is configured to cause the excitation light from the excitation light source to be reflected on the curved surface and fluorescence from the phosphor to pass through the curved surface. The surface-curved dichroic mirror neither substantially converges nor substantially diverges the light that passes through, but performs a diverging operation on the excitation light that is reflected on the curved surface so as to form a virtual image.