Red Laser and LED Illumination for Projector White Balance
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Solution Overview
Problem
Increasing green light output in optical projection systems without a corresponding increase in red light output leads to a green tint in white light production, as red LEDs cannot supply enough red light due to the etendue limitations of the projector system, limiting the projector's output lumens.
Innovation Solution
Incorporating a red laser with a longer wavelength than the red LED, combined with dichroic filters, to increase the total red output and balance the green light output, allowing for increased lumens while maintaining proper white balance, using a top side pump green LED architecture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If green LED output is increased to improve brightness, then illumination intensity is improved, but the white light develops a green tint due to insufficient red light
Solution Approach 1:
The patent combines light from multiple sources (red LED, green LED, and red laser) to create a composite illumination system. The red laser is merged with the red LED output through optical combining, and both are combined with green LED light to produce balanced white light with improved brightness and proper color balance.
Solution Approach 2:
The patent uses optical filters as intermediaries to manage the combination of different light wavelengths. These filters selectively transmit and block specific wavelengths, enabling precise control over the mixing of red and green light to achieve proper white balance while maintaining high brightness.
2Illumination intensity
If red LED current is increased to supply more red light, then red light output is improved, but power consumption increases and etendue limitations are reached
Solution Approach 1:
The patent uses a red laser to generate additional red light that complements the red LED output. The laser creates a copy or supplement of the red light source, allowing the system to achieve higher red light output without proportionally increasing the red LED current and associated power consumption.
Solution Approach 2:
The patent changes the wavelength parameter by introducing a red laser with a longer wavelength than the red LED. This parameter change allows the system to access a different portion of the red spectrum that can be combined with the LED light, effectively increasing total red output while managing power consumption through the laser's efficient operation.
3Stability of the object's composition
If a red laser with longer wavelength than red LED is added, then total red output increases to balance green light, but device complexity increases
Solution Approach 1:
The patent designs the optical system with multi-functional components that handle multiple wavelengths and paths. The optical filters and combining optics are designed to simultaneously manage red LED light, red laser light, and green LED light, allowing a single optical train to perform multiple functions and reducing the need for separate dedicated optical paths for each source.
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 approach enhances the brightness of the projection system by up to 40% and improves efficiency by reducing the red LED current while meeting lumens requirements, achieving a proper white balance and increased power efficiency.
Implementation Method 1
a red laser, where the red laser has a longer wavelength than the red LED
Implementation Method 2
a filter configured to reflect the red light at approximately the first wavelength and transmit the red light at approximately the fourth wavelength
Implementation Method 3
Some green LEDs have a phosphor on the output side of a blue LED. This type of green LED is called a converted green LED. An internal blue LED within the green LED shines on the phosphor, which causes the phosphor to emit green light.
Implementation Method 4
a lens configured to receive the red light at the first wavelength, the blue light at the second wavelength, the green light at the third wavelength, and the red light at the fourth wavelength, and to transmit the received red, blue, and green light to an optical projector
Data Source
AI summary
A system includes a red light emitting diode (LED), a blue LED, and a green LED. The system also includes a red laser, a first filter, a second filter, and a lens. The system includes a first optical path that includes the red LED, the red laser, the first filter, the second filter, and the lens, where the first filter has a filter response to transmit red light from the red laser and to reflect red light from the red LED. The system also includes a second optical path that includes the blue LED, the green LED, the second filter, and the lens, where the second filter has a filter response to transmit blue light from the blue LED, to transmit green light from the green LED, to reflect red light from the red laser, and to reflect red light from the red LED.