Focal Plane Shutter with Opposing Biasing Springs
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Solution Overview
Problem
High-speed focal plane shutters face blade damage due to large impact when stopped, as existing designs use springs with the same biasing direction, leading to excessive stress on the blades.
Innovation Solution
A focal plane shutter design incorporating a board with blades, an electromagnet, a drive lever, and biasing members with opposing biasing directions to manage the movement and adjustment of blades, using a first biasing member to always bias the drive lever away from the electromagnet and a second biasing member to adjust the drive arm in the opposite direction, with stepwise and stepless adjustment mechanisms to control the biasing forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high-speed blades are used to achieve high shutter speed, then the shutter speed is improved, but the impact on blades when stopped increases causing potential damage
Solution Approach 1:
The patent employs a first spring and a second spring with opposite biasing directions to create counterbalancing forces. The first spring biases the drive arm in the direction of blade movement, while the second spring biases it in the opposite direction. This counterweight mechanism allows the system to achieve high-speed operation while the opposing spring forces absorb and reduce the impact when blades are stopped, preventing blade damage.
Solution Approach 2:
The patent adjusts the spring constants and pre-compression amounts of the two springs to optimize the balance between achieving high shutter speed and reducing impact force. By carefully selecting and adjusting these parameters, the system can operate at high speeds while the spring forces are tuned to minimize the harmful impact when the blades come to a stop.
2Device complexity
If two springs with the same biasing direction are used, then the structure is simple, but the impact on blades when stopped increases
Solution Approach 1:
The patent introduces a second spring with biasing direction opposite to the first spring, creating a counterbalance system. While this increases the number of components, it significantly reduces the impact on blades by having the second spring's force oppose the first spring's force during deceleration and stopping, thereby protecting the blades from damage.
3Speed
If high-speed blades are used, then the shutter speed is improved, but the risk of blade damage increases
Solution Approach 1:
The opposing spring configuration acts as a protective mechanism that becomes particularly important at high speeds. The second spring's counterbalancing force reduces the impact stress on blades during stopping, thereby enhancing blade durability and reliability while allowing the system to operate at high shutter speeds.
Solution Approach 2:
The spring system provides beforehand cushioning by being pre-compressed and ready to absorb impact forces. The second spring, biased in the opposite direction, is positioned to counteract the impact force before the blades come to a stop, thereby protecting the blades from damage and improving reliability.
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 design reduces the impact and sound when the blades stop, allowing for smoother operation and reduced risk of damage by managing the biasing forces effectively, thereby enhancing the longevity and performance of high-speed shutter blades.
Implementation Method 1
an electromagnet supported by the board; a drive lever adsorbed to and held by the electromagnet
Data Source
AI summary
A focal plane shutter includes: a board including an opening; blades opening and closing the opening; an electromagnet supported by the board; a drive lever adsorbed to and held by the electromagnet, and swingably supported by the board; a drive arm connected to the drive lever, swingably supported by the board, and driving the blades; a first biasing member always biasing the drive lever away from the electromagnet and moving the blades; a first adjusting member that stepwisely adjusts a biasing force of the first biasing member; a second biasing member always biasing the drive arm in a direction opposite to a biasing direction of the first biasing member to such an extent that the blades are moved in accordance with the biasing force of the first biasing member; and a second adjusting member that steplessly adjusts a biasing force of the second biasing member.