Neutral Density Filter with Gradation for Image Resolution
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Solution Overview
Problem
Existing image pickup apparatuses face issues with light diffraction due to the insertion of ND filters, leading to degraded image resolution and luminance shocks, especially during still image shooting, as they require sudden aperture adjustments which disrupt exposure control.
Innovation Solution
An image pickup apparatus with an ND filter having a transparent portion and a density gradation portion, where the controller controls the filter's closing operation at different speeds to prevent light diffraction and luminance shocks by smoothly adjusting the aperture, using the transparent portion for rapid changes and the gradation portion for gradual adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the ND filter is inserted into the aperture to reduce light amount, then exposure control is improved, but light diffraction occurs due to sudden aperture changes, degrading image resolution
Solution Approach 1:
The ND filter is divided into a transparent portion and a density gradation portion. The transparent portion enables rapid light amount adjustment, while the density gradation portion gradually transitions light intensity to prevent sudden changes, thereby resolving the contradiction between exposure control and image resolution.
Solution Approach 2:
Different portions of the ND filter have different optical properties: the transparent portion allows full light transmission for quick adjustment, while the density gradation portion provides gradual light attenuation. This local differentiation enables the filter to simultaneously achieve rapid response and smooth transitions, preventing light diffraction.
2Speed
If the aperture is suddenly stopped down to control exposure, then exposure control speed is improved, but luminance shock occurs on the screen, disrupting continuity
Solution Approach 1:
The ND filter separates the functions of rapid adjustment and smooth transition by dividing it into a transparent portion for speed and a density gradation portion for stability. This segmentation allows the system to achieve both fast exposure control and continuous luminance output.
Solution Approach 2:
The density gradation portion acts as an intermediary between the transparent portion and the image pickup element, gradually attenuating light to smooth out sudden luminance changes while the transparent portion provides the rapid adjustment capability.
3Device complexity
If the diaphragm mechanism and ND filter are simultaneously controlled, then device complexity is reduced, but the ability to independently optimize exposure parameters is limited
Solution Approach 1:
The ND filter with its dual portions serves multiple functions: it acts as a standard ND filter for exposure control while also functioning as a diffraction prevention element through its density gradation portion. This multi-functionality allows independent control of exposure parameters without increasing overall device complexity.
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 prevents light diffraction and maintains image resolution during still image shooting while ensuring continuous luminance, enhancing exposure control for both still and moving image shooting by minimizing sudden luminance changes.
Implementation Method 1
an ND filter for limiting the amount of the light incident on the CCD sensor from the diaphragm mechanism
Implementation Method 2
a density gradation portion, and a controller adapted to control a closing operation of the filter for closing the aperture, such that the closing operation is performed at different speeds between when the gradation portion covers the aperture of the diaphragm mechanism and when the transparent portion covers the aperture of the diaphragm mechanism
Implementation Method 3
the filter having a transparent portion for selectively opening and closing the aperture of the diaphragm mechanism
Data Source
AI summary
An image pickup apparatus which is capable of preventing light diffraction from being caused by a density step or a thickness step of a filter, thereby preventing degradation of resolution during still image shooting, and securing the dynamic range of exposure control during both moving image shooting and still image shooting. In the image pickup apparatus, an image pickup element converts light incident thereon from a lens into an electric signal. A diaphragm mechanism changes the amount of light incident on the image pickup element. An ND filter covers an aperture of the diaphragm mechanism such that the aperture can be opened and closed, thereby adjusting the amount of light incident on the image pickup element after passing through the aperture. A controller controls a closing operation of the ND filter for closing the aperture, such that the closing operation is performed at different speeds between when a gradation portion of the ND filter covers the aperture and when a transparent portion of the ND filter covers the aperture.