Focal Plane Shutter Blade Bending Prevention
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Solution Overview
Problem
Focal plane shutters with blades of different rigidities can increase shutter weight, affect speed, and cause damage to image pickup elements due to impact and bending, especially when made of synthetic resin.
Innovation Solution
A focal plane shutter design featuring first, second, and third boards with openings, a blade for opening and closing these openings, and a holding member between the second and third boards to prevent the blade from bending towards the image pickup element, using synthetic resin for all components and a metal holding member to manage impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the blade includes plural blades having different rigidities (first blade and second blade with different materials), then the blade can prevent bending toward the image pickup element, but the whole weight of the shutter increases and shutter speed is affected
Solution Approach 1:
The patent applies local quality by making only the second blade (the one closer to the image pickup element) have higher rigidity through different material or structural design, while the first blade maintains lower rigidity. This localized differentiation provides sufficient bending prevention where needed without unnecessarily increasing the weight of the entire shutter assembly.
2Strength
If the first blade is made of synthetic resin and the second blade is made of metal, then the blade rigidity is improved, but the second blade might cut the first blade to make dust
Solution Approach 1:
The patent applies homogeneity by making both blades from the same material (synthetic resin) to ensure compatible mechanical properties. This eliminates the risk of the more rigid second blade cutting or damaging the first blade, preventing dust generation while still providing sufficient rigidity through the overall blade structure and support mechanisms.
3Weight of moving object
If both the first and second blades are made of synthetic resin, then the weight is reduced, but the second blade might not ensure high rigidity to suppress bending under large impact
Solution Approach 1:
The patent applies composite materials by combining synthetic resin with metal components in the blade support structure. The blades themselves remain lightweight synthetic resin, while metal support elements provide the necessary rigidity and impact resistance. This composite approach maintains low blade weight while ensuring sufficient structural strength to prevent bending under impact.
4Area of stationary object
If the blade is made large to cover larger image pickup elements, then the shutter can handle larger formats, but the impact on the blade increases and bending becomes difficult to suppress
Solution Approach 1:
The patent applies segmentation by dividing the blade structure into multiple segments or sections. This allows the blade to be designed with varying thickness, rigidity, or support intervals along its length, providing enhanced bending resistance where needed (near the image pickup element) while maintaining overall size and coverage area for larger image pickup elements.
Data Source
AI summary
A focal plane shutter includes: first, second, and third boards respectively including openings through which light enters an image pickup element from an object side, and arranged in this order from the object side toward the image pickup element side; a blade arranged between the first and second boards and capable of opening and closing the openings; and a holding member arranged between the second and third boards, not coupled to the blade, and holding the second board from the image pickup element side.