Camera Focus Lens Control via Acceleration Sensor
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Solution Overview
Problem
Conventional digital cameras take a long time to focus when the user causes a displacement of the camera in the optical axis direction due to camera shake, leading to inefficient auto focus operations.
Innovation Solution
An imaging apparatus equipped with a focus lens, an acceleration sensor, and a controller that detects movement in the optical axis direction and adjusts the focus lens position based on the detected movement and contrast value to quickly achieve focus, preventing initial unnecessary focus lens movements and optimizing focus acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the camera moves in the optical axis direction due to user displacement, then the focus state becomes incorrect, but the conventional AF system takes a long time to detect and correct the focus error
Solution Approach 1:
The acceleration sensor detects camera movement in advance before the focus error actually occurs. By detecting the acceleration in the optical axis direction and integrating it to predict the focus lens displacement, the system proactively adjusts the focus lens position before the focus evaluation value deteriorates, thereby reducing focus acquisition time while maintaining accuracy
Solution Approach 2:
The system continuously monitors both the acceleration sensor output and the focus evaluation value, using this feedback to dynamically adjust the focus lens position. The controller integrates acceleration data over time to calculate predicted focus lens displacement and combines this with real-time focus evaluation to optimize the focus acquisition process under camera movement conditions
2Speed
If the focus lens is moved based solely on acceleration sensor data, then focus correction speed improves, but focus accuracy may deteriorate due to integration errors
Solution Approach 1:
The system uses the focus evaluation value as a feedback mechanism to verify and correct the focus lens position predicted from acceleration sensor data. By comparing the actual focus evaluation with the predicted position, the system can detect integration errors and adjust accordingly, maintaining both speed and accuracy
Solution Approach 2:
The system dynamically adjusts the integration time period of the acceleration sensor based on the detected acceleration magnitude. When large acceleration is detected, the integration time is shortened to reduce error accumulation, while maintaining longer integration times for smaller accelerations to preserve precision. This adaptive parameter change optimizes both correction speed and 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
Enables the digital camera to rapidly and accurately focus even when the camera moves relative to the object, reducing the time required to achieve a focus state and improving focus accuracy.
Implementation Method 1
an acceleration sensor that detects acceleration in an optical axis direction
Implementation Method 2
an imaging unit that captures an image of an object
Data Source
AI summary
An imaging apparatus of the present disclosure includes a body, an imaging unit provided in the body, the imaging unit for capturing an image of an object and generating an image, a focus lens movable in an optical axis direction, the focus lens for adjusting a focus state of the image, an evaluation value detector for detecting a focus evaluation value of the image, a movement detector for detecting a moving direction and an amount of movement of the body in the optical axis direction, and a controller for controlling movement of the focus lens. The controller determines a direction to which the focus lens is to be moved, based on the moving direction of the body in the optical axis direction detected by the movement detector and the focus evaluation value detected by the evaluation value detector.