Focal Plane Shutter Braking Mechanism for Reducing Blade Rebound
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Solution Overview
Problem
Focal plane shutters face challenges in achieving high braking force for shutter blades during fast shutter operations, leading to time lags and uneven exposure due to large spring biasing forces, and the braking member's position is not suitable for braking the leading blade before imaging, causing collisions and smearing issues.
Innovation Solution
A focal plane shutter design with a braking member that uses friction with a base plate to apply a large braking force independently of the driving and charging portions, featuring a cam mechanism and actuators to position the braking member effectively, allowing for high braking force without rebound and collision risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a large spring biasing force is used to increase braking force for fast shutter operations, then the braking force is improved, but time lag and uneven exposure occur due to rebound
Solution Approach 1:
A damping member is introduced as an intermediary between the braking member and the leading blade. This damping member absorbs the rebound energy through frictional damping, preventing the rebound from affecting the leading blade while still allowing the braking member to apply large braking force. The damping member acts as a buffer that mediates between the high-force braking system and the sensitive leading blade.
2Force
If the braking member is positioned to brake the leading blade before imaging, then braking effectiveness is improved, but collision occurs between the braking member and leading blade driving portion
Solution Approach 1:
The braking member is preliminarily positioned in the extended state (away from the leading blade) before the imaging operation begins. This preliminary positioning prevents collision with the leading blade driving portion. When imaging starts, the braking member is then moved to the engaged state to apply braking force, ensuring both collision-free operation and effective braking.
Solution Approach 2:
The braking member is designed to be movable between two states: an extended state where it is retracted from the leading blade path to prevent collision, and an engaged state where it contacts the leading blade to apply braking force. This dynamic repositioning allows the system to avoid harmful collisions while maintaining braking effectiveness when needed.
3Device complexity
If the braking member is integrated with the leading blade driving portion, then device complexity is reduced, but braking force and positioning independence are compromised
Solution Approach 1:
The braking function is segmented from the leading blade driving portion into an independent braking mechanism. The braking member is driven by a separate braking member driving portion that can independently control the braking force and timing. This segmentation allows the braking system to operate independently without being constrained by the leading blade driving mechanics, enabling larger and more controllable braking force.
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
Enables effective braking of the leading blade with a large braking force across multiple operating modes, reducing time lags and smearing, and maintaining stable operation by independently positioning the braking member and optimizing the braking force.
Implementation Method 1
a braking member for braking the leading blade through friction with a base plate when the leading blade opens the opening
Implementation Method 2
featuring a cam mechanism and actuators to position the braking member effectively
Data Source
AI summary
A focal plane shutter has a base plate with an opening; a leading and trailing blade opening and closing the opening; a leading blade driver; a trailing blade driver; a charging portion; a braking member; and a brake driver. The leading blade driver drives the leading blade through a first biasing force of a first biasing member and drives the leading blade through a second biasing force of a second biasing member. The trailing blade driver drives the trailing blade by a third biasing force of a third biasing member. The charging portion applies the second biasing force to the second biasing member and applies the third biasing force to the third biasing member. The braking member brakes the leading blade through friction and the brake driver moves the braking member to brake the leading blade, independently of the leading blade driver, the trailing blade driver, and the charging portion.