Quasi-bandpass filter for dual mode camera
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Solution Overview
Problem
Monitoring cameras face challenges in optimizing image quality across different lighting conditions due to sensitivity to both visible and near-infrared light, leading to issues with color fidelity and sharpness, and existing solutions are complex and costly, with mechanical filters prone to failure.
Innovation Solution
A dual mode camera system equipped with a quasi-bandpass filter that attenuates near-infrared light while allowing visible light to pass, along with an image sensor sensitive to both wavelengths, and a light source that emits near-infrared illumination in low-light conditions, enabling operation in color or monochrome modes based on ambient light levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a mechanical filter is used to block near-infrared light, then near-infrared attenuation is achieved, but device complexity and reliability deteriorate due to moving parts
Solution Approach 1:
The patent replaces the mechanical filter system with a fixed quasi-bandpass filter that has no moving parts. This filter is designed to transmit visible light while blocking near-infrared light through its optical properties rather than mechanical movement, thereby eliminating reliability issues associated with mechanical components.
Solution Approach 2:
The patent changes the optical parameters of the filter by using a fixed quasi-bandpass filter with specific transmission characteristics. The filter is designed to have high transmission in the visible range (400-700nm) and high attenuation in the near-infrared range (700-1100nm), achieving the desired light filtering through parameter optimization rather than mechanical adjustment.
2Device complexity
If a fixed quasi-bandpass filter is used, then device complexity is reduced, but near-infrared transmittance may be insufficient
Solution Approach 1:
The patent optimizes the parameters of the fixed quasi-bandpass filter to achieve the desired balance. The filter is designed with specific transmission characteristics including peak visible transmittance greater than 80% and peak near-infrared transmittance between 1-50%, ensuring sufficient near-infrared blocking while maintaining visible light transmission.
3Illumination intensity
If the camera operates in low-light conditions without near-infrared illumination, then visible light image quality is maintained, but illumination insufficiency occurs
Solution Approach 1:
The patent converts the typically harmful near-infrared light into a useful illumination source for low-light conditions. By using a near-infrared light source and a fixed quasi-bandpass filter that allows controlled near-infrared transmission, the system enables reliable low-light operation while minimizing the harmful effects of near-infrared on visible light image quality.
4Manufacturing precision
If near-infrared light is completely blocked, then color fidelity is improved, but low-light image capture capability deteriorates
Solution Approach 1:
The patent optimizes the filter's transmission parameters to achieve a balance between color fidelity and low-light capability. The fixed quasi-bandpass filter is designed with peak near-infrared transmittance between 1-50%, which is sufficient to block most near-infrared light for good color fidelity while still allowing enough transmission for low-light operation when combined with near-infrared illumination.
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 system effectively captures high-quality images in varying lighting conditions by minimizing near-infrared impact on image quality and providing sufficient illumination in low-light scenarios, reducing complexity and cost compared to existing solutions.
Implementation Method 1
a quasi-bandpass filter for filtering the light received by the aperture to provide filtered light, the filtered light including visible light and attenuated near-infrared light
Implementation Method 2
an image sensor for detecting image data in response to the filtered light
Implementation Method 3
a light source having an emission band overlapping at least a portion of the near-infrared band of the quasi-bandpass filter
Data Source
AI summary
A dual mode camera may have a camera module and a light source. The camera module may include a quasi-bandpass filter for passing visible light and passing an attenuated portion of near-infrared light to an image sensor for detection. A processor may determine an ambient lighting condition corresponding with an amount of ambient visible light detected by a photodetector. In response to a first ambient lighting condition, the processor may send a first control signal to an encoder to encode image data in monochrome, and another signal to activate a light source. In response to a second ambient lighting condition, the processor may send a second control signal to the encoder to encode image data in color. The light source may emit a band of near-infrared light corresponding with an atmospheric absorption band. The quasi-bandpass filter may attenuate a portion of near-infrared light corresponding with the same atmospheric absorption band.