Two-Stage Autofocusing Lens Positioning for Faster Image Capture
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Solution Overview
Problem
Current autofocusing methods in cameras are time-consuming due to the need for extensive frequency domain transformations at multiple lens positions, necessitating a two-stage process that still results in inefficient focus adjustment.
Innovation Solution
An automatic focusing method that adjusts the relative positions of a lens and sensor module in an image capture device using a first unit to determine multiple states, then refines to a best state using a finer second unit, driven by a processor to achieve clearer images, utilizing a digital signal processor and mechanical components for precise focus adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency domain transformation is executed for each lens position to achieve accurate focus, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent divides the focus adjustment process into two stages: a first stage that samples clarity values at multiple lens positions to identify a candidate position, and a second stage that performs detailed frequency domain transformation only around the candidate position. This segmentation reduces the total number of positions requiring computationally intensive transformations while maintaining focus accuracy.
Solution Approach 2:
The patent performs preliminary sampling of clarity values at multiple lens positions before executing frequency domain transformation. This preliminary action identifies a candidate position that narrows down the search space, allowing the subsequent frequency domain transformation to be performed at fewer positions while still achieving accurate focus measurement.
2Measurement precision
If the number of lens positions is increased from 20 to 200 to improve focus precision, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The patent segments the 200 lens positions into a coarse sampling phase and a fine adjustment phase. During coarse sampling, clarity values are obtained at fewer positions to identify a candidate region. During fine adjustment, detailed frequency domain transformation is performed only within this candidate region, effectively reducing the number of positions requiring intensive processing while maintaining the precision benefits of having 200 available positions.
Solution Approach 2:
The patent applies partial action by performing frequency domain transformation at only a subset of lens positions rather than all 200 positions. The transformation is concentrated around the candidate position identified through preliminary sampling, performing just enough transformations to achieve accurate focus without the excessive computation time that would result from transforming all positions.
3Productivity
If two-stage autofocusing is implemented to reduce computation time, then productivity is improved, but loss of time remains high in practice
Solution Approach 1:
The patent replaces the traditional two-stage mechanical focus adjustment process with a computational approach that uses clarity value sampling and candidate position identification to guide the final focus adjustment. This substitution allows for more intelligent decision-making about which positions require detailed transformation, reducing the total time spent in both stages combined.
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 significantly reduces computation time and improves focus adjustment efficiency by interpolating the best position based on clarity values, allowing for faster and more accurate autofocusing.
Implementation Method 1
a sensor module converting light beams into electric signals
Data Source
AI summary
An autofocusing method is implemented in an image capture device comprising a lens and a sensor module. The relative positions of lens and the sensor module are adjusted for autofocusing based on a factor. First, the relative positions of the lens and the sensor module are adjusted based on a first unit of the factor to determine a plurality of states of the lens and the sensor module, where the lens renders clearer images on the sensor module. The states are utilized to estimate a best state achievable by focusing based on a second unit of the factor, where the lens renders a clearest image on the sensor module. The second unit is finer than the first unit. The lens or the sensor module is driven to the best state.