Projector Wavelength Variable Interference Filter for Brightness Stability
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Solution Overview
Problem
Projectors face inaccuracies in detecting light levels due to wavelength shifts in laser light sources over time, leading to fluctuations in brightness and white balance, especially when using optical sensors with color filters that rely on fixed transmittance characteristics.
Innovation Solution
A projector system utilizing a light source with both blue and yellow laser light, where the blue light is modulated and combined with yellow fluorescence, and a photodetector equipped with a wavelength variable interference filter to accurately detect and adjust light levels, ensuring consistent brightness and white balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If optical sensors using color filters are used to detect light amounts, then the structure is simple and cost-effective, but detection accuracy deteriorates when light source wavelength shifts occur
Solution Approach 1:
The patent applies the dynamics principle by making the interference filter wavelength-variable. Instead of using a fixed color filter, the system employs an interference filter whose transmission wavelength can be dynamically adjusted to match the actual wavelength of the laser light source, thereby maintaining accurate detection despite wavelength shifts over time
Solution Approach 2:
The patent applies parameter changes by modifying the transmission wavelength parameter of the interference filter to adapt to changes in the light source wavelength. The control unit adjusts the interference filter's wavelength parameter based on detected wavelength shifts, ensuring the filter remains synchronized with the light source characteristics
2Illumination intensity
If laser light sources are used to provide stable single-wavelength light, then brightness consistency is improved, but wavelength stability deteriorates over time due to light source deterioration
Solution Approach 1:
The patent applies feedback by implementing a closed-loop control system where the wavelength detection unit continuously monitors the laser light source wavelength, and the control unit uses this feedback information to adjust the interference filter's wavelength parameter, compensating for drift and maintaining synchronization
Solution Approach 2:
The patent applies preliminary action by proactively adjusting the interference filter wavelength before detection accuracy is significantly compromised. The system continuously tracks wavelength shifts and makes preemptive adjustments to the filter parameters, preventing degradation of detection performance
3Device complexity
If fixed transmittance color filters are used, then the device complexity is reduced, but adaptability to wavelength changes deteriorates
Solution Approach 1:
The patent transforms the static color filter into a dynamic interference filter system where the transmission characteristics can be adjusted. This adds controlled complexity to the filter mechanism while dramatically improving adaptability to different wavelengths
Solution Approach 2:
The patent applies universality by designing an interference filter system that can adapt to multiple different wavelengths. Instead of requiring separate filters for different light sources, the single adjustable interference filter can be tuned to match various laser wavelengths, making the system universally applicable
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 solution allows for precise detection and adjustment of light levels, maintaining consistent image quality and white balance even as the light sources deteriorate, by using a wavelength variable interference filter to adapt to shifting light spectra.
Implementation Method 1
a photodetector including a wavelength variable interference filter
Implementation Method 2
a photodetector that includes a wavelength variable interference filter and detects an amount of the first light and an amount of the second light
Data Source
AI summary
In a projector, an optical sensor including a wavelength variable interference filter is disposed in the vicinity of the optical path of illumination light that exits out of an illumination system and travels to a color separation system, and the optical sensor detects the amounts of blue light and fluorescence contained in the illumination light. A processor of the projector adjusts the amounts of blue light and fluorescence based on the result of the detection performed by the optical sensor.