Optical Scanning Device Phosphor Irradiation Efficiency
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Solution Overview
Problem
Conventional optical scanning devices waste significant light energy due to prolonged irradiation of phosphors beyond their fluorescence lifetime, leading to inefficient light emission.
Innovation Solution
The optical scanning device optimizes the rotational position of the light emitting unit to align the minor axis of the excitation light spot with the scanning direction, utilizing first and second irradiation systems with different spot diameters to reduce total continuous irradiation time, allowing phosphors to emit light efficiently without significantly increasing scanning speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the excitation light irradiates the phosphor panel continuously, then the phosphors remain in excited state for extended periods, but this causes waste of excitation light energy and reduces emission efficiency
Solution Approach 1:
The patent applies periodic action by controlling the excitation light to irradiate the phosphor panel in periodic pulses rather than continuous illumination. The irradiation time is precisely controlled to be less than the fluorescence lifetime of the phosphors, allowing phosphors to return to ground state between pulses. This periodic irradiation pattern eliminates energy waste from continuously illuminating already-excited phosphors while maintaining high emission efficiency.
2Loss of time
If the scanning speed is increased to reduce irradiation time, then the total continuous irradiation time decreases, but this requires significantly higher scanning speed which increases system complexity
Solution Approach 1:
The patent applies local quality by using optical systems with different spot diameters (first and second irradiation systems) to irradiate different regions of the phosphor panel. By controlling the spot size and position locally, the system achieves reduced total continuous irradiation time without requiring uniformly high scanning speed across the entire panel. This localized irradiation approach allows precise control of irradiation duration while maintaining manageable scanning speeds.
3Productivity
If the light emitting unit rotational position is optimized to align minor axis with scanning direction, then the irradiation pattern improves phosphor emission efficiency, but this requires precise positioning control
Solution Approach 1:
The patent applies preliminary action by pre-positioning the light emitting unit at a specific rotational angle before operation begins. The minor axis of the light emitting unit is aligned with the scanning direction in advance, establishing the optimal irradiation pattern from the start. This preliminary positioning ensures that subsequent scanning operations automatically achieve the desired elliptical spot orientation and phosphor irradiation efficiency without requiring real-time adjustment during operation.
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 reduces the total continuous irradiation time to be less than the fluorescence lifetime, minimizing light energy waste and enhancing phosphor emission efficiency.
Implementation Method 1
When light such as laser light is irradiated onto the phosphors, the electrons of fluorescent molecules are excited, and the vibration level of electrons is moved immediately from the ground state to the excited state. After that, excess energy of electrons is dissipated and hence the vibration level of electrons drops to a vibration level as the lowest order of a first excited state Then, fluorescence is emitted from the phosphors in a process where the electrons return from the lowest-order vibration level to the level of the ground state.
Data Source
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AI summary
There is provided a headlight unit 1 configured to make phosphors emit light efficiently. The headlight unit 1 includes a laser-light emission device 14, a light deflector 15, a phosphor panel 20, and a projector lenses 19 in order along a light traveling path. The rotational position of a light emitting unit 45 of the laser-light emission device 14 about an optical axis is so set that the minor axis direction of an optical spot Sp generated on a light incident surface 41 of the phosphor panel 20 will be a direction along a scanning direction Hc of the optical spot Sp on the light incident surface 41.