Focal-Plane Shutter Rear Curtain Electromagnet Control
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Solution Overview
Problem
Digital cameras with focal-plane shutters face increased power consumption and noise due to prolonged magnetization of rear-curtain electromagnetic actuators during long exposures, affecting image quality.
Innovation Solution
A digital camera design featuring a focal-plane shutter with a first and second front-curtain drive member, a rear-curtain drive member, and a lock mechanism, where the rear-curtain electromagnetic actuator is magnetized only immediately before exposure completion and demagnetized afterwards, reducing electrical conduction time and power consumption, and allowing for live view image display and noise removal in long exposures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the rear-curtain electromagnetic actuator is continuously magnetized during long exposure, then the rear curtains remain held in the fully opened state, but power consumption increases and heat generation causes noise
Solution Approach 1:
The patent applies preliminary action by holding the rear curtains in the fully opened state using a mechanical structure (rear curtains holding structure) before the exposure begins, rather than continuously magnetizing the electromagnetic actuator during the entire exposure period. This allows the actuator to be magnetized only briefly to initiate the holding state, then remain demagnetized throughout the long exposure, significantly reducing power consumption while maintaining the required functionality
Solution Approach 2:
The patent replaces the electromagnetic actuation system with a mechanical holding structure (rear curtains holding structure including holding arm and holding position) that can maintain the rear curtains in the opened state without requiring continuous electrical power. This mechanical substitution eliminates the need for prolonged electromagnetic field maintenance, thereby reducing power consumption and heat generation during long exposures
2Duration of action of stationary object
If the rear-curtain electromagnetic actuator is continuously magnetized during long exposure, then the rear curtains remain held in the fully opened state, but heat generation increases causing noise
Solution Approach 1:
The patent uses preliminary action by establishing the rear curtains holding state through a mechanical structure before exposure begins, allowing the electromagnetic actuator to be demagnetized during the exposure period. This eliminates heat generation from continuous magnetization, thereby preventing noise while maintaining the required exposure duration
Solution Approach 2:
The patent substitutes the electromagnetic holding mechanism with a mechanical holding structure that maintains the rear curtains in the opened state without electrical power. This mechanical substitution eliminates the heat generation source that would otherwise cause noise during long exposures
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 solution reduces power consumption and heat generation, thereby improving image quality by minimizing noise and extending the camera's operational efficiency during long exposures.
Implementation Method 1
a rear-curtain electromagnetic actuator that inhibits the movement of the rear-curtain drive member in the first direction using the rear-curtain running spring in a direct or indirect manner
Implementation Method 2
a front-curtain electromagnetic actuator and a rear-curtain electromagnetic actuator that respectively inhibit the movement of the second front-curtain drive member and the rear-curtain drive member in the first direction using the front-curtain running spring and the rear-curtain running spring
Implementation Method 3
a second front-curtain drive member that is biased in the first direction by a front-curtain running spring and abuts on the first front-curtain drive member to move the first front-curtain drive member in the first direction
Data Source
AI summary
Provided are a digital camera and a control method of a digital camera which are capable of reducing power consumption in a focal-plane shutter capable of performing a normal opening operation. In the focal-plane shutter capable of performing the normal opening operation, in a case where a shutter release switch is operated, exposure using an electronic shutter is started. Thereafter, curtain running preparation for magnetizing a front-curtain electromagnet and a rear-curtain electromagnet and unlocking a second front-curtain drive member and a rear-curtain drive member locked in charge positions by a lock mechanism, which is a curtain running preparation operation of the focal-plane shutter, is performed immediately before exposure of a still image is completed. The exposure is ended by demagnetizing the rear-curtain electromagnet after the curtain running preparation is ended and causing rear curtains to run in a closing direction through the rear-curtain drive member by a biasing force of a rear-curtain running spring. Accordingly, an electrical conduction time of the rear-curtain electromagnet is shortened, and thus, power consumption is reduced.