Auto-Focus Frame Rate Adjustment for Moving Subjects
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Solution Overview
Problem
The contrast AF method for imaging apparatuses faces challenges in maintaining focusing accuracy at low luminance due to increased noise influence, which is exacerbated by the need to decrease frame rates, compromising the ability to capture moving subjects effectively.
Innovation Solution
An imaging apparatus that adjusts its frame rate based on subject and camera movement, using a gyro-sensor to determine dynamic conditions and adjust exposure settings to maintain high frame rates for accurate focus detection during low-luminance captures of moving subjects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the frame rate of the image pickup device is decreased to increase exposure amount and inhibit noise influence, then focusing accuracy is improved, but the ability to capture moving subjects deteriorates
Solution Approach 1:
The patent applies dynamics by making the frame rate adjustable rather than fixed. The control circuit dynamically changes the frame rate between a first frame rate (lower) and a second frame rate (higher) based on movement detection results, allowing the system to adapt to different subject conditions and resolve the contradiction between focusing accuracy and motion capture capability
Solution Approach 2:
The patent implements feedback through the movement determination circuit that detects subject or imaging apparatus movement and provides this information to the control circuit. This feedback loop enables the system to automatically adjust the frame rate based on actual movement conditions, maintaining both focusing accuracy and motion capture performance
2Speed
If the frame rate is increased to capture moving subjects, then motion capture ability is improved, but noise influence on AF evaluation value increases
Solution Approach 1:
The system dynamically adjusts the frame rate based on movement detection, using a higher second frame rate when movement is detected and a lower first frame rate when no movement is detected. This dynamic adjustment allows the system to capture moving subjects effectively while minimizing noise influence during static conditions
Solution Approach 2:
The patent changes the frame rate parameter between two discrete values (first frame rate and second frame rate) based on movement conditions. This parameter change strategy allows the system to optimize between motion capture and noise reduction by selecting the appropriate frame rate for the current situation
Data Source
AI summary
An imaging apparatus moves a focus lens on the basis of an imaging signal of an image pickup device to perform a focal adjustment. The image pickup device images a subject. The imaging apparatus includes an evaluation value calculation circuit, a control circuit, and a movement determination circuit. The evaluation value calculation circuit extracts a predetermined signal component from an imaging signal to generate an evaluation value. The control circuit performs a focal adjustment on the basis of the evaluation value. The movement determination circuit determines whether or not the subject or the imaging apparatus is moving. The control circuit changes a frame rate of the image pickup device from a first frame rate to a second frame rate higher than the first frame rate when the movement determination circuit determines that the subject or the imaging apparatus is moving.