Segmented Neutral Density Filters for Compact Camera Lens Barrels
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Solution Overview
Problem
Existing light amount adjusting devices, such as those using neutral density filters, face challenges in reducing size due to the need for large diameters and increased space requirements, especially when trying to accommodate larger aperture diameters and non-stepwise light adjustment in compact camera systems.
Innovation Solution
A light amount adjusting device comprising two neutral density filters with transparent and non-transparent areas that move between in-use and retracted positions, allowing for overlapping configurations that minimize the device's size by ensuring the transparent areas cover the aperture when retracted and the gradation areas attenuate light when in use, with a driving mechanism to control their positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single ND filter is used to cover the entire aperture, then light amount can be adjusted, but the device outer diameter becomes at least three times the aperture diameter, increasing camera size
Solution Approach 1:
The single ND filter is divided into multiple ND filters (first ND filter and second ND filter). Each filter covers only a portion of the aperture area, allowing the filters to be smaller in diameter than the aperture. This segmentation enables the device outer diameter to be reduced while still achieving full aperture coverage when filters are in the in-use position.
Solution Approach 2:
The patent transitions from a single large-diameter filter covering the entire aperture to multiple smaller filters arranged in specific positions. By utilizing spatial arrangement and overlapping configurations in different dimensions, the system achieves complete aperture coverage with smaller individual filter elements, reducing the overall device diameter.
2Adaptability or versatility
If two ND filters with gradation portions are used for non-stepwise light adjustment, then light amount can be adjusted continuously, but the width of the gradation portion increases the device size
Solution Approach 1:
The light adjustment function is segmented across multiple filters rather than relying on a single wide gradation portion. Each ND filter has its own gradation portion, and by combining multiple filters with different optical densities and gradation configurations, the system achieves non-stepwise light adjustment without requiring any single filter to have an excessively wide gradation area.
Solution Approach 2:
The patent uses composite filter configurations where multiple ND filters with different optical properties (different optical densities, different gradation portions) are combined. This composite approach allows for continuous light adjustment by varying the overlap positions of filters with different characteristics, achieving versatile light control without increasing individual filter sizes.
3Ease of operation
If ND filters with transparent portions are used, then light amount can be adjusted, but the retraction space increases because the filters need to be completely retracted from the aperture
Solution Approach 1:
The aperture coverage is segmented across multiple ND filters rather than requiring a single filter to completely cover and retract from the entire aperture. This allows the filters to be positioned such that their combined coverage area matches the aperture area when in use, while reducing the retraction distance needed since each filter only needs to move within a limited range to achieve proper positioning.
Solution Approach 2:
The patent arranges ND filters in nested or overlapping configurations where filters are positioned to cover specific aperture regions. This nesting approach allows filters to be compactly arranged and reduces the retraction space required, as filters can be partially overlapped and don't need to clear the entire aperture diameter during retraction.
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 configuration reduces the overall size of the light amount adjusting device, minimizes retraction space, and maintains image quality by ensuring continuous optical density and preventing optical path length differences, thus addressing the challenge of compactness and image quality in cameras with large aperture diameters.
Implementation Method 1
a first filter, including a transparent area and a non-transparent area, configured to move between a retracted position and an in-use position
Data Source
AI summary
A light amount adjusting device includes ND filters rotating around shafts serving as rotation shafts and moving between in-use positions and retracted positions, arranged on a base plate. The respective ND filters include uniform density portions, gradation portions, and transparent portions. If the ND filters are in the retracted positions, the transparent portions of the respective ND filters overlap in an area facing an aperture to cover the entire aperture with the transparent portions. If the ND filters are in the in-use positions, the gradation portions of the respective ND filters overlap in an area facing the aperture to cover the entire aperture with the gradation portions and the uniform density portions. Moreover, a combined density acquired when the gradation portions overlap in just proportion is substantially the same as an optical density of each of the uniform density portions.