Projector Optical Filter and Aperture for Chromatic Aberration Control
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Solution Overview
Problem
Existing interactive projectors face challenges in achieving accurate alignment and calibration due to the need for high-performance imaging devices that can suppress chromatic aberration across broad wavelength bands, leading to blurs and focus issues when capturing both visible and infrared light.
Innovation Solution
A projector system with an imaging section that includes an optical filter and aperture capable of being inserted and extracted, allowing for varying f-numbers to suppress axial chromatic aberration by selectively transmitting light in specific wavelength bands, enabling accurate alignment and calibration for interactive writing on a projection screen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an imaging device with high performance is used to suppress chromatic aberration in a broad wavelength band, then both visible light and infrared light can be captured without blurs, but the device complexity and cost increase significantly
Solution Approach 1:
The patent divides the imaging process into two separate modes: one for visible light (pattern image) and one for infrared light (detected light). By using an optical filter that can be inserted or extracted, the system segments the wavelength bands, allowing each mode to be optimized independently rather than requiring a single high-performance device to handle both bands simultaneously.
Solution Approach 2:
The patent changes the f-number parameter of the aperture based on the wavelength band being imaged. By adjusting the f-number to be larger (smaller aperture opening) when imaging visible light and smaller (larger aperture opening) when imaging infrared light, the system optimizes the depth of field and light intensity for each specific wavelength band, thereby suppressing axial chromatic aberration without requiring a complex high-performance imaging device.
2Illumination intensity
If the optical filter is extracted from the light path to capture visible light, then the pattern image can be imaged, but the focal position may not be aligned in positions other than on the optical axis causing blurs
Solution Approach 1:
The patent adjusts the f-number parameter dynamically based on which optical filter is in place. When the visible light cutoff filter is extracted to allow visible light imaging, the system increases the f-number (reduces aperture opening) to increase the depth of field and maintain focus alignment across the entire projection area, not just on the optical axis. This parameter adjustment compensates for the potential focus misalignment that would otherwise occur.
3Ease of operation
If the aperture f-number is kept constant, then the device operation is simple, but axial chromatic aberration occurs due to the difference in wavelength band between image light and detected light
Solution Approach 1:
The patent makes the aperture dynamic by automatically adjusting the f-number based on the insertion or extraction state of the optical filter. The control unit detects which filter is in place and相应地 adjusts the aperture opening, making the system adaptive to different wavelength bands. This dynamic adjustment suppresses axial chromatic aberration while maintaining ease of operation, as the adjustment is automated and does not require manual intervention.
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 improves the accuracy of alignment and calibration, allowing for reliable interactive projector operations by minimizing axial chromatic aberration and ensuring focus across the entire range of the projection area, even during proximity projections.
Implementation Method 1
an optical filter, which can be inserted and extracted, adapted to reduce the image light from the projection main unit and transmit detected light in a wavelength band other than a wavelength band of the image light
Implementation Method 2
by the aperture varying the f-number in accordance with the insertion and the extraction of the optical filters, it is possible to suppress the axial chromatic aberration caused by the difference in wavelength band between the image light and the detected light
Data Source
AI summary
In an imaging section (imaging device), optical filters constituting an optical filter device are inserted and extracted, and an aperture varies an f-number in accordance with the insertion and the extraction of the optical filters. Thus, during the writing operation to the surface of the projection screen, namely during the interactive projector operation, entering of the light in the wavelength band other than that of the detected light DL is suppressed while capturing the detected light DL with the necessary light intensity, and during an alignment (a calibration), the axial chromatic aberration caused by the difference in wavelength band between the pattern image light GL as the image light and the detected light DL is suppressed to achieve an improvement in accuracy.