Focal-plane shutter current adjustment for temperature stability
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Solution Overview
Problem
Focal-plane shutters experience variations in exposure period due to temperature changes, primarily caused by changes in the mechanical portion and coils, leading to inconsistent blade run-up periods and exposure times.
Innovation Solution
Adjusting the current value flowing through the leading and trailing blade coils to synchronize the run-up periods of the blades with temperature changes, ensuring consistent exposure periods across varying temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the leading blade and trailing blade are driven by electromagnets, then the shutter operation is automated and precise, but the exposure period varies depending on temperature change
Solution Approach 1:
The patent adjusts the current value flowing through the coils as temperature changes to compensate for thermal expansion effects. By dynamically changing the electrical parameter (current) in response to temperature variations, the system maintains consistent blade run-up periods and exposure times despite environmental changes.
Solution Approach 2:
The patent implements a feedback mechanism where temperature information is used to adjust the current supplied to the coils. This closed-loop control ensures that the exposure period remains stable by continuously compensating for temperature-induced variations in blade actuation timing.
2Reliability
If the current value through the coils is adjusted to compensate for temperature changes, then the exposure period stability is improved, but the control system complexity increases
Solution Approach 1:
Instead of adding complex mechanical compensation mechanisms, the patent simply adjusts the electrical current parameter based on temperature. This approach maintains system simplicity while achieving the desired stability by exploiting the existing electromagnetic actuation system's responsiveness to current variations.
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 adjustment stabilizes the exposure period by aligning the temperature-dependent variations in the run-up periods of the leading and trailing blades, thereby maintaining consistent exposure times despite temperature fluctuations.
Implementation Method 1
a leading blade actuator and a trailing blade actuator respectively driving the leading blade and the trailing blade, and respectively including a leading blade coil and a trailing blade coil
Data Source
AI summary
A focal-plane shutter includes: a mechanical portion including: a board including an opening; and a leading blade and a trailing blade capable of opening and closing the opening; and a leading blade actuator and a trailing blade actuator respectively driving the leading blade and the trailing blade, and respectively including a leading blade coil and a trailing blade coil, wherein a current value flowing through at least one of the leading blade coil and the trailing blade coil is adjusted such that one of variations in a leading blade run-up period and a trailing blade run-up period depending on a temperature change corresponds to the other one.