Stepping Motor Aperture Control for Exposure Accuracy
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Solution Overview
Problem
Existing light quantity adjusters for imaging apparatuses, using stepping motors, face challenges in achieving precise exposure control for both still and moving pictures due to limitations in resolution and accuracy, leading to issues like over-exposure or under-exposure, especially when trying to match exposure control with the imaging of a moving picture.
Innovation Solution
A light quantity adjuster that includes a blade member and a stepping motor, with a control section that increases the rotational speed of the stepping motor after the resistance changes from static friction to dynamic friction during aperture closure, allowing for faster aperture closure without the need to shorten the electric period of the stepping motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the electric period of the stepping motor is shortened to reduce exposure time, then the exposure time is reduced, but the resolution of exposure is restricted by the halt accuracy of the stepping motor and circuitry resolution
Solution Approach 1:
The patent applies dynamics by changing the rotational speed of the stepping motor during operation. The control section increases the rotational speed after static friction transitions to dynamic friction, allowing the system to adapt its speed characteristics during the aperture closure process rather than maintaining a constant speed throughout.
Solution Approach 2:
The patent changes the operational parameters of the stepping motor by adjusting its rotational speed based on the friction state. The control section monitors the transition from static to dynamic friction and相应地 increases the rotational speed, thereby optimizing both exposure time and resolution without shortening the electric period.
2Device complexity
If the stepping motor is driven at constant speed to close the aperture, then the control is simple, but the actual change in light quantity forms a wavy curve resulting in longer exposure time
Solution Approach 1:
The patent implements feedback by having the control section monitor the friction state of the stepping motor and adjust the rotational speed accordingly. The control section increases the rotational speed after detecting the transition from static to dynamic friction, thereby eliminating the wavy curve in light quantity change and reducing exposure time while maintaining controllable complexity.
3Loss of time
If the rotational speed of the stepping motor is increased to reduce exposure time, then the exposure time is reduced, but the friction resistance causes delay and transient response making the actual light quantity change wavy
Solution Approach 1:
The patent applies preliminary action by pre-planning the rotational speed adjustment based on the expected friction transition. The control section is configured to increase the rotational speed at the specific moment when static friction transitions to dynamic friction, anticipating the friction change and compensating for it before it affects the light quantity control accuracy.
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 ensures accurate exposure control matching for moving pictures and enables suitable shutter operations for still pictures, reducing the risk of over-exposure or under-exposure and maintaining efficient power consumption.
Implementation Method 1
a stepping motor that moves the blade member to open/close the aperture
Implementation Method 2
after a resistance acting on the stepping motor changes from static friction to dynamical friction
Data Source
AI summary
A light quantity adjuster includes: a blade member forming an aperture; a stepping motor that moves the blade member to open/close the aperture; and a control section that controls driving of the stepping motor, and increases a rotational speed of the stepping motor after a resistance acting on the stepping motor changes from static friction to dynamical friction in case of closing the aperture.