Camera Autofocus Using Temperature and Posture Sensor Offsets
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Plastic lenses in camera modules suffer from low heat resistance, causing significant changes in focal length due to ambient temperature variations, which complicates autofocus operations, especially when combined with posture-related position adjustments lacking feedback control.
Innovation Solution
An autofocus method and system that utilizes temperature and posture sensors to determine offsets, adjusting the lens moving range based on these measurements, allowing for open-loop control of the actuator to achieve focus without feedback, thereby compensating for temperature and posture-induced focal length changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a plastic lens is used to reduce cost, then manufacturing cost is reduced, but heat resistance deteriorates causing focal length changes with temperature
Solution Approach 1:
The patent applies parameter changes by using temperature and posture sensors to detect environmental conditions, then dynamically adjusting the lens moving range parameters to compensate for thermal expansion and gravitational effects on the plastic lens focal length
Solution Approach 2:
The patent implements feedback control by continuously monitoring temperature and posture parameters, then using this information to adjust the autofocus range and maintain accurate focus despite environmental changes affecting the plastic lens
2Measurement precision
If the lens moving range is increased to accommodate temperature and posture variations, then focus accuracy is maintained, but autofocus speed deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-determining temperature and posture offsets through calibration, then using these pre-calculated compensation values to quickly adjust the lens moving range without requiring extensive search during actual autofocus operations
Solution Approach 2:
The patent dynamically changes the lens moving range parameters based on real-time temperature and posture conditions, optimizing the search range to be just sufficient for compensation rather than covering all possible variations, thus maintaining speed while ensuring accuracy
3Device complexity
If open-loop control is used to simplify the system, then device complexity is reduced, but control precision deteriorates due to lack of feedback
Solution Approach 1:
The patent implements a form of feedback by using temperature and posture sensors to provide environmental condition information that is used to adjust the control parameters, achieving compensation without requiring complex closed-loop position feedback mechanisms
Solution Approach 2:
The patent uses temperature and posture offsets as intermediary parameters that mediate between the simple open-loop actuator control and the environmental conditions, allowing indirect compensation for thermal and gravitational effects without complex direct position feedback
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 approach enhances autofocus speed and accuracy by reducing the margin needed for temperature and posture adjustments, leading to faster focus positioning and improved auto-focusing performance.
Implementation Method 1
A plastic lens has a disadvantage of low heat resistance. In other words, the plastic lens greatly contracts and expands according to ambient temperature, thereby significantly changing a focal length.
Implementation Method 2
receiving measured posture information obtained by measuring a posture of the camera
Data Source
AI summary
A camera controller controls a camera module, which includes a plastic lens and an actuator controlling a position of the lens in an open-loop mode. The camera controller includes an offset determiner configured to determine a first offset corresponding to a measured temperature of a camera and a second offset corresponding to a measured posture of the camera, a lens moving range determiner configured to determine a moving range of the lens based on the first offset and the second offset, and an autofocus calculator configured to output a position control signal for controlling a position of the lens and seek a focus position of the lens based on the lens moving range.