Imaging Device Autofocus via Sensor-Lens Coordination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing autofocus systems in imaging devices face limitations in accelerating focus acquisition due to the need for high-speed movement of focus lenses, which results in increased size and power consumption, and overshoot issues during lens stopping.
Innovation Solution
The implementation of an imaging device with a focus lens drive unit, image sensor movement drive unit, and controllers that coordinate the movement of both the focus lens and image sensor to accelerate autofocus by moving the image sensor before the focus lens stops, maintaining focus until the lens is fully stopped, and using phase difference detection pixels for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the focus lens is moved at a high speed to accelerate autofocus, then the autofocus speed is improved, but the device size and power consumption increase due to requiring a large motor
Solution Approach 1:
The patent combines the movement functions of the focus lens and image sensor into a coordinated system. The image sensor moves simultaneously with the focus lens during autofocus, allowing the focus lens to be driven at lower speeds while achieving the same effective focusing speed, thereby reducing motor size and power consumption.
Solution Approach 2:
The patent implements dynamic control where the image sensor movement is adjusted based on the focus lens position and focusing state. The sensor moves during focusing and maintains position during overshoot cancellation, optimizing the balance between autofocus speed and power consumption throughout the focusing process.
2Productivity
If the focus lens is moved at a high speed to accelerate autofocus, then the autofocus speed is improved, but overshoot occurs at the time of stopping the focus lens
Solution Approach 1:
The patent applies preliminary action by moving the image sensor in advance during the focusing process. This allows the system to achieve focus before the focus lens completes its movement, enabling the lens to slow down and stop more gradually without causing overshoot, thus maintaining both speed and precision.
Solution Approach 2:
The image sensor acts as an intermediary that compensates for the focus lens movement. By coordinating sensor movement with lens movement, the system reduces the impact of lens stopping dynamics, preventing overshoot while maintaining fast autofocus performance.
3Productivity
If a large motor is used to move the focus lens at a higher speed, then the autofocus speed is improved, but the device size increases
Solution Approach 1:
The patent merges the focusing function with image sensor movement capability. By utilizing the image sensor's movement to contribute to the focusing process, the system achieves fast autofocus without requiring a large motor for the focus lens, thereby reducing overall device size.
Data Source
AI summary
Provided are an imaging device capable of accelerating AF and a focusing control method thereof. A focus lens drive unit (16) that drives a focus lens (12), and an image sensor movement drive unit (120) that moves an image sensor (110) along an optical axis (L) are included. A target position of the focus lens (12) for focusing on a subject is set, and the focus lens (12) is moved toward the target position. The image sensor (110) is moved before the focus lens (12) reaches the target position such that focusing is performed. A focusing state is maintained by moving the image sensor (110) so as to follow the focus lens (12) after the focusing is performed.