Lens Unit Control Method for Contrast Autofocus Accuracy
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Solution Overview
Problem
Existing lens units face challenges in conducting contrast autofocus due to insufficient movement of focus lenses, resulting in inaccurate contrast value acquisition and potential failure in achieving sufficient focus accuracy.
Innovation Solution
A control method and lens unit configuration that adjust the movement of multiple focus lenses based on different rules depending on their position within a 'range of satisfactory optical performance', using distinct movement profiles for in-range and out-of-range positions to ensure accurate focus adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a focus lens is moved over a sufficient range to acquire contrast values for conducting contrast autofocus, then focus accuracy is improved, but the lens unit size and complexity increase
Solution Approach 1:
The patent combines multiple focus lenses into a single lens unit, allowing them to move cooperatively as an integrated system. This merging enables the lenses to share the focus adjustment function, achieving sufficient contrast value acquisition range without requiring each individual lens to move independently over large distances, thus improving focus accuracy while controlling lens unit complexity.
Solution Approach 2:
The patent implements dynamic control of focus lens movement by adjusting the movement amount of each focus lens based on its current position and the required focus adjustment. The control circuit dynamically determines movement profiles that optimize the range of motion only when necessary for contrast autofocus, rather than maintaining fixed large movement ranges, thereby achieving focus accuracy while minimizing lens unit complexity.
2Adaptability or versatility
If the range of motion of focus lenses is increased to enable accurate contrast autofocus, then focus adjustment capability is improved, but the lens unit becomes larger
Solution Approach 1:
Multiple focus lenses are merged into a cooperative system where they move together to achieve focus adjustment. This combination allows the lens unit to maintain a compact size while the coordinated movement of multiple lenses provides the necessary adaptability for accurate contrast autofocus, avoiding the need for any single lens to have an excessively large range of motion.
Solution Approach 2:
The focus adjustment function is segmented across multiple focus lenses rather than relying on a single lens. Each lens contributes to the overall focus adjustment capability, allowing the system to achieve high adaptability for contrast autofocus with smaller individual lens movement ranges, thereby keeping the lens unit length compact.
3Measurement precision
If multiple focus lenses are moved independently over large ranges, then contrast value acquisition is improved, but power consumption increases
Solution Approach 1:
The control circuit uses feedback from the imaging unit to determine when and how much to move each focus lens. By monitoring the focus state and contrast values, the system adjusts lens movement dynamically, acquiring necessary contrast values while minimizing unnecessary movement. This feedback mechanism ensures accurate contrast value acquisition while reducing power consumption by avoiding excessive lens movement.
Solution Approach 2:
The system dynamically adjusts the movement of focus lenses based on real-time focus requirements rather than moving lenses over fixed large ranges. The control circuit optimizes movement profiles to achieve sufficient contrast value acquisition with minimal movement, adapting the lens movement strategy to current conditions and thereby reducing power consumption while maintaining measurement precision.
Data Source
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AI summary
There is provided a lens unit equipped with multiple focus lenses provided inside a lens barrel, multiple actuators corresponding to the respective multiple focus lenses and configured to move each of the multiple focus lenses inside the lens barrel, and a control circuit configured to control movement of the multiple focus lenses according to different rules between a case of a position of each of the multiple focus lenses being inside a designated range of satisfactory optical performance, and a case of being outside the range.