Focal-Plane Shutter Control for Continuous Shooting Blackout Reduction
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Solution Overview
Problem
In continuous shooting mode, the blackout period of the live view image occurs due to the time required to release the locking of the front and rear curtains, leading to defects like blurriness and uneven exposure in live view-electronic front-curtain imaging compared to normal imaging.
Innovation Solution
An imaging device with a focal-plane shutter and control unit that manages the front and rear curtains to minimize the blackout period by optimizing the travel preparation and exposure control, allowing the live view image to be displayed continuously during continuous shooting by delaying the second curtain travel preparation and prioritizing the first curtain travel preparation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the front curtain and rear curtain are caused to travel to take a static image in continuous shooting mode, then the exposure quality is improved, but the blackout period of the live view image increases
Solution Approach 1:
The patent applies preliminary action by performing the first curtain travel preparation (exciting electromagnetic actuators and releasing lock mechanism) before the second curtain travel preparation (releasing front curtain prevention and causing front curtain to travel). This sequencing allows the exposure mechanism to be ready in advance, reducing the overall blackout period while maintaining exposure quality through proper timing of curtain movements.
2Ease of operation
If the lock mechanism holds the second front curtain-drive member and rear curtain-drive member at charge positions, then the shutter can be held in open state for live view, but the time to release locking increases the blackout period
Solution Approach 1:
The lock mechanism is engaged in advance during charge operation to hold the curtains in open state for live view display. The electromagnetic actuators are excited and the lock mechanism is released as the first curtain travel preparation, before the actual exposure begins. This preliminary engagement and timely release minimizes the blackout period while maintaining ease of live view operation.
Solution Approach 2:
The patent replaces purely mechanical locking with an electromagnetic locking system. The electromagnetic actuators can be excited and deactivated rapidly, providing faster response compared to mechanical springs alone. This substitution reduces the time required to release the locking and initiate curtain travel, thereby reducing the blackout period.
3Adaptability or versatility
If the front curtain is held open by electromagnetic actuator during charge operation, then live view imaging is enabled, but the front curtain may move unintentionally during continuous shooting
Solution Approach 1:
The electromagnetic actuator is excited in advance as part of the first curtain travel preparation before continuous shooting begins. This preliminary excitation ensures the actuator is ready to maintain or adjust the front curtain position, preventing unintentional movement during shooting while enabling live view imaging capability.
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
The solution effectively shortens the blackout period of the live view image during continuous shooting, improving the accuracy and speed of continuous shooting while maintaining distance measurement accuracy and exposure quality.
Implementation Method 1
current is supplied to a front curtain solenoid and a rear curtain solenoid and the movement of a front curtain drive pin and a rear curtain drive pin (the front curtain and the rear curtain) is electromagnetically fixed
Implementation Method 2
a return spring that biases the front curtain in the closing direction by a biasing force smaller than a biasing force of the front curtain-travel spring
Data Source
AI summary
There are provided an imaging device and a method of controlling the imaging device that can shorten the blackout period of a live view image in a case where a front curtain and a rear curtain are moved to continuously take static images. In a case where continuous shooting is performed, a focal-plane shutter is shifted to a normally open state to allow a live view image to be displayed during the continuous shooting. A front curtain-electromagnet and a rear curtain-electromagnet are excited to prevent the rotational movement of a second front curtain-drive lever and a second rear curtain-drive lever in a first direction after the focal-plane shutter is shifted to the normally open state; first curtain travel preparation for causing the second front curtain-drive lever and the rear curtain-drive lever to be moved to non-charge positions from charge positions is performed to release the prevention of the travel of the front curtain in a closing direction, which is performed by the front curtain-locking lever, from a point of time later than a point of time when the first curtain travel preparation is to be started; and second curtain travel preparation for causing the front curtain to travel in the closing direction to fully close an exposure aperture portion is performed.