Projector Light Source Layout for Blue Leakage Control
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Solution Overview
Problem
Existing light source apparatuses for projectors using fluorescence from phosphors face issues with blue light leakage due to angular components incident at angles smaller than the critical angle, leading to an unbalanced ratio of yellow and blue light, which hinders the production of desired white light.
Innovation Solution
The apparatus includes a first light source outputting excitation light, a second light source outputting blue light, a wavelength converter, and optical layers and guides to adjust the angle of incidence of blue light, along with an incident angle adjusting system to optimize the ratio of yellow and blue light, using interchangeable convex lenses to control the angle of incidence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If blue light emitting diodes are disposed to face a side surface of a transparent rod and blue light enters via the side surface, then the light source apparatus can be constructed, but blue light leaks out via side surfaces due to angular components incident at angles smaller than the critical angle, making it difficult to adjust the ratio between yellow light and blue light
Solution Approach 1:
The patent introduces a light guide as an intermediary component between the blue light source and the phosphor rod. The light guide redirects blue light to enter the phosphor rod through its end surface rather than the side surface, eliminating direct side-surface incidence that causes leakage. This mediator enables proper light transmission while preventing the harmful leakage effect.
Solution Approach 2:
The patent changes the parameter of light entry location from side surface to end surface of the phosphor rod. By modifying where the blue light enters the phosphor rod (from lateral incidence to axial incidence), the critical angle condition is satisfied and blue light leakage is prevented, enabling proper adjustment of the yellow-blue light ratio.
2Device complexity
If blue light enters the transparent rod via side surface, then the apparatus structure is simplified, but a large amount of blue light leaks out via side surfaces, resulting in inability to produce desired white light
Solution Approach 1:
The light guide serves as a mediator that transports blue light from the LED source to the phosphor rod's end surface. This intermediary structure prevents direct side-surface entry into the phosphor rod, thereby eliminating blue light leakage while maintaining efficient energy utilization for white light production.
Solution Approach 2:
The patent changes the dimensional approach of light entry from lateral (side surface) to longitudinal (end surface) direction. By transitioning the light entry path to another spatial dimension (through the end surface rather than the side), the patent prevents leakage while maintaining structural efficiency.
3Device complexity
If blue light is allowed to enter freely via side surface, then the optical path is simplified, but the ratio between yellow light and blue light cannot be adjusted, preventing production of desired white light
Solution Approach 1:
The light guide acts as a controlled intermediary that manages the optical path between the blue LED and phosphor rod. This mediator provides a controlled entry path through the end surface, enabling precise control over light transmission while maintaining a relatively simple overall optical structure.
Solution Approach 2:
The patent modifies the light entry parameter from side-surface incidence to end-surface incidence of the phosphor rod. This parameter change enables controlled transmission of blue light that can be properly converted to yellow light, allowing adjustment of the yellow-blue light ratio to produce desired white light while keeping the optical path simple.
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 enhances the production of balanced white light by reducing blue light leakage and improving the efficiency of light utilization, allowing for improved light source performance.
Implementation Method 1
a wavelength converter configured to convert the first light and the second light into third light having a third wavelength band different from the first wavelength band and the second wavelength band
Implementation Method 2
a first optical layer disposed between the first light source and the wavelength converter and configured to transmit the first light and reflect the third light
Implementation Method 3
a light guide disposed between the first optical layer and the wavelength converter and configured to guide each of the first light, the second light, and the third light
Implementation Method 4
a second optical layer disposed between the incident angle adjusting system and the light guide and configured to transmit the second light and reflect the third light
Data Source
AI summary
A light source apparatus according to an aspect of the present disclosure includes a first light source configured to output first light; a second light source configured to output second light; a wavelength converter configured to convert the first light and second light into third light; a first optical layer configured to transmit the first light and reflect the third light; a light guide configured to guide light; an incident angle adjusting system configured to adjust an angle of incidence of the second light with respect to the wavelength converter; and a second optical layer configured to transmit the second light and reflect the third light. The wavelength converter has a first surface, a second surface, and a third surface. The first light enters the wavelength converter via the first optical layer and the light guide and via the third surface. The third light exits out of a region on the first surface side of the light guide. The second light enters the incident angle adjusting system, which adjusts the angle of incidence of the second light, and the resultant second light enters a region on the second surface side of the light guide via the second optical layer, and part of the second light enters the wavelength converter via the third surface and is converted into the third light by the wavelength converter, and another part of the second light exits out of a region on the first surface of the light guide.