Autofocus Lens Control Using Phase Difference Defocus Data
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Solution Overview
Problem
Existing image pickup apparatuses face inefficiencies in autofocus speed and operation quality due to the lack of effective initial position driving of the focus lens, particularly when the lens is not initially set to an in-focus position, leading to increased AF time and reduced accuracy.
Innovation Solution
An image pickup apparatus and method that includes a focus detection system using both contrast and phase difference detection to calculate a defocus amount, allowing for controlled initial position driving of the focus lens before the focusing operation, optimizing the starting position for faster and more accurate autofocus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If initial position driving of the focus lens is performed without using defocus amount information, then the focusing operation can be executed, but the autofocus speed is increased and operation quality is reduced
Solution Approach 1:
The patent applies preliminary action by calculating the defocus amount before the focusing operation starts, and using this information to determine the initial driving direction and range of the focus lens. This preliminary calculation and positioning action reduces the time needed during the actual focusing operation, thereby decreasing AF time while maintaining or improving autofocus speed.
Solution Approach 2:
The patent uses feedback by continuously monitoring the defocus amount and adjusting the initial position driving accordingly. The control circuit receives feedback on the focus lens position and defocus state, and dynamically adjusts the driving parameters to optimize the focusing process, reducing unnecessary driving time while ensuring accurate focus.
2Ease of operation
If the focus lens is not initially positioned at in-focus position, then the lens can be in any starting position, but unnecessary initial position driving is executed reducing efficiency
Solution Approach 1:
The patent performs preliminary calculation of the defocus amount and determination of the necessary initial driving parameters before executing the focusing operation. This allows the system to start from any position while efficiently calculating the optimal driving path, avoiding unnecessary driving and improving focusing efficiency regardless of the initial lens position.
Solution Approach 2:
The patent implements dynamic adjustment of the initial position driving based on real-time defocus amount measurement. The control circuit dynamically determines the driving direction and distance according to the current lens position and focus state, allowing flexible starting positions while optimizing the driving path to eliminate unnecessary movements and improve efficiency.
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 enables faster autofocus operations by minimizing unnecessary initial position driving and optimizing the focus lens position, thereby improving autofocus speed and accuracy, especially when the lens is initially out of focus.
Implementation Method 1
an image pickup device configured to pick up an image of object light via an image-acquiring optical system including a focus lens to generate an image pickup signal
Implementation Method 2
a first focus detection circuit configured to calculate an evaluation value indicative of a contrast based on the image pickup signal output by the image pickup device
Implementation Method 3
a second focus detection circuit configured to perform focus detection based on phase difference detection to output a defocus amount of the image-acquiring optical system
Data Source
AI summary
An image pickup apparatus includes a first focus detection circuit configured to calculate an evaluation value indicative of a contrast based on an image pickup signal output by an image pickup device, a second focus detection circuit configured to perform focus detection based on phase difference detection to output a defocus amount of an image-acquiring optical system including a focus lens, and a control circuit configured to control a focusing operation of detecting a position of the focus lens where the evaluation value is indicative of an extreme value based on an output from the first focus detection circuit. Based on the defocus amount output by the second focus detection circuit, the control circuit controls initial position driving of the focus lens executed before the focusing operation is performed.