Laser Light Source Device with Polarized Phosphor Conversion
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Solution Overview
Problem
Conventional light source devices using light-emitting diodes have low light output, making miniaturization difficult, and electroluminescent elements are not suitable for projection type displays due to low luminance, while laser diodes offer high power efficiency but pose eye safety concerns with coherent light.
Innovation Solution
A light source device incorporating a laser diode with a polarized laser beam and a phosphor layer excited at an optimal angle to convert coherent light into incoherent light, utilizing a polarization conversion element to enhance light use efficiency and achieve a compact, high-output design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a laser diode is used as a light source, then power/light conversion efficiency is improved, but eye safety deteriorates due to coherent light
Solution Approach 1:
A phosphor layer is introduced as an intermediary between the laser diode and the external environment. The phosphor layer absorbs the coherent laser light and converts it to incoherent light through photoluminescence, thereby maintaining the high conversion efficiency of the laser diode while eliminating the eye safety hazards associated with coherent light
Solution Approach 2:
The patent changes the optical parameters of the light by using a phosphor layer to convert the coherent light from the laser diode into incoherent light. This parameter change (from coherent to incoherent) resolves the eye safety issue while preserving the energy efficiency benefits of the laser diode
2Illumination intensity
If light-emitting diodes are used to increase light output, then brightness is improved, but device size increases making miniaturization difficult
Solution Approach 1:
The patent changes the operational parameters of the laser diode by controlling the incident angle and polarization of the laser beam to optimize light extraction efficiency. This allows achieving high light output from a compact laser diode source rather than requiring multiple or larger light-emitting diodes
3Use of energy by moving object
If the incident angle of laser beam to phosphor layer is optimized, then light use efficiency is improved, but optical system complexity increases
Solution Approach 1:
The patent optimizes specific parameters (incident angle between 0° and 90°, P-polarization) of the laser beam to maximize light use efficiency in the phosphor layer. By carefully controlling these parameters, high efficiency is achieved without requiring complex optical systems with multiple components
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 significantly improves light use efficiency in light source devices, enabling a compact and high-output design suitable for various applications, including projection type displays, while addressing eye safety concerns by converting coherent laser light into incoherent light.
Implementation Method 1
a laser diode for emitting a laser beam polarized in a particular direction
Implementation Method 2
a light collection optical system for condensing the laser beam emitted from the laser diode
Implementation Method 3
a phosphor layer excited by the laser beam condensed by the light collection optical system of the light source unit to discharge incoherent light
Implementation Method 4
a polarization conversion element for rotating the polarizing direction of a laser beam emitted from a laser diode
Data Source
AI summary
A light source device includes a light source unit concluding LD element (1) for emitting a laser beam polarized in a particular direction and lens (2) for condensing the laser beam emitted from LD element (1) and phosphor layer (3) excited by the laser beam condensed by lens (2) of the light source unit to discharge incoherent light. The incident angle of the laser beam to phosphor layer (3) is larger than 0° and smaller than 90°, and the laser beam enters phosphor layer (3) as P-polarized light.