Lens Device Filter Switching Mechanism for High-Luminance Imaging
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Solution Overview
Problem
Surveillance cameras face challenges in capturing high-luminance subjects without inducing image deterioration due to diffraction phenomena and smear, as existing methods either reduce image quality or fail to adequately manage light levels for both high and low luminance conditions.
Innovation Solution
A lens device incorporating an image-formation optical system with a diaphragm mechanism and a filter section that includes an infrared-ray cutoff filter and a neutral density filter, along with a filter switching mechanism to control the placement of these filters during high-luminance photography, allowing for reduced light exposure without diffraction and smear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the diaphragm is reduced to reduce light amount for high-luminance subjects, then the amount of light radiated on the imaging element is reduced, but a diffraction phenomenon occurs which deteriorates image quality
Solution Approach 1:
An ND filter is introduced as an intermediary element between the diaphragm and imaging element. The filter attenuates light before it reaches the diaphragm, allowing the diaphragm to maintain a larger aperture while still achieving the desired light reduction. This mediator approach solves the contradiction by providing light control without requiring small aperture settings that cause diffraction.
2Illumination intensity
If the ND filter density is increased to reduce light amount for high-luminance subjects, then the amount of light is reduced sufficiently, but the minimum illuminance for low-luminance subjects increases which hinders photographing in dark places
Solution Approach 1:
The ND filter system is made dynamic through automatic switching between different density filters based on scene luminance conditions. The control unit selects appropriate filter densities in real-time, allowing the system to provide strong light reduction for bright scenes while maintaining full light transmission for dark scenes. This dynamic adaptation resolves the contradiction between light reduction capability and low-luminance photographing capability.
3Illumination intensity
If the electronic shutter speed is increased to reduce light amount, then the amount of light is reduced, but the imaging element remains exposed to high-luminance light which causes smear phenomenon deteriorating image quality
Solution Approach 1:
The ND filter performs preliminary light attenuation before light reaches the imaging element during high-luminance exposure. By reducing the light intensity in advance, the imaging element is protected from overexposure and smear effects even when using faster shutter speeds. This preliminary action approach solves the contradiction by preventing the harmful effect before it occurs.
4Illumination intensity
If the aperture of the diaphragm is reduced further for supersensitive cameras to compensate for high sensitivity, then light amount is reduced, but diffraction phenomenon becomes more likely which deteriorates image quality
Solution Approach 1:
The ND filter serves as a mediator that handles light reduction independently of the diaphragm aperture. This allows the diaphragm to maintain optimal aperture settings for supersensitive cameras without being forced to small openings that would cause diffraction. The filter absorbs the light control function, freeing the diaphragm to operate in its optimal range and avoiding diffraction-related image quality deterioration.
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 effectively reduces light exposure during high-luminance photography, preventing diffraction and smear while maintaining sufficient illuminance for low-luminance conditions, thereby enhancing image quality and adaptability of the camera.
Implementation Method 1
a first infrared-ray cutoff filter and a composite filter into which a second infrared-ray cutoff filter and a neutral density filter are superimposed integrally one on top of the other
Implementation Method 2
a filter section that is provided on a subject side of the imaging element and through which the luminous flux incident on the image-formation optical system travels
Implementation Method 3
an image-formation optical system that converges an incident luminous flux at an imaging element, to form an image
Implementation Method 4
when the diaphragm of the lens is reduced, a diffraction phenomenon occurs in a light ray passing through the diaphragm
Data Source
AI summary
A lens device comprises: an image-formation optical system that converges an incident luminous flux at an imaging element, to form an image; a diaphragm mechanism provided in the image-formation optical system; and a filter section that is provided on a subject side of the imaging element and through which the luminous flux incident on the image-formation optical system travels, wherein the filter section comprises: an infrared-ray cutoff filter; and a neutral density filter, and wherein the lens device further comprises a filter switching mechanism that places the infrared-ray cutoff filter and the neutral density filter in a range through which the luminous flux travels at the time of photographing of a high-luminance subject.