Focusing Apparatus Vertical Direction Evaluation
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Solution Overview
Problem
Conventional focusing methods fail to accurately derive the peak focus evaluation value for images with significant changes in the vertical direction, leading to incorrect focusing, especially in high-speed capturing modes.
Innovation Solution
A focusing apparatus and method that includes a focus lens, an image pickup device, memory for storing image signals, and components to derive focus evaluation values in different directions, compare peak values, and determine the focus lens position based on these evaluations, ensuring accurate focusing even with images having small changes in the horizontal but large changes in the vertical direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional focusing method using contrast scheme is used, then focusing can be performed by calculating focus evaluation value, but correct peak value cannot be derived for images with small horizontal changes and large vertical changes
Solution Approach 1:
The patent applies dimensionality change by switching from horizontal direction evaluation to vertical direction evaluation when horizontal contrast is insufficient. The processing unit calculates focus evaluation values in the vertical direction by reading image signals column-wise instead of row-wise, thereby resolving the contradiction when horizontal changes are small but vertical changes are large.
2Device complexity
If focus evaluation value is calculated in reading direction of image pickup device, then processing is simplified, but accurate focusing cannot be achieved for images with anisotropic contrast patterns
Solution Approach 1:
The patent implements dynamic adaptability by enabling the processing unit to switch between horizontal and vertical direction evaluation based on image characteristics. This dynamic approach allows the system to maintain processing simplicity while achieving accurate focusing for anisotropic contrast patterns by selecting the appropriate evaluation direction.
Solution Approach 2:
The processing unit is designed with multi-functionality to calculate focus evaluation values in both horizontal and vertical directions. This universal capability allows the same hardware to handle diverse image types with different contrast patterns, resolving the contradiction between processing simplicity and focusing accuracy.
3Productivity
If peak value is derived from single direction evaluation, then focusing speed is maintained, but focusing accuracy deteriorates for images with directional contrast variations
Solution Approach 1:
The patent employs periodic action by alternately evaluating focus in horizontal and vertical directions and selecting the period (direction) that yields the higher peak value. This periodic evaluation strategy maintains focusing speed while improving accuracy for images with directional contrast variations, as the system systematically checks both directions and selects the optimal one.
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 correct focusing for images with varying contrast patterns, particularly those with small horizontal but large vertical changes, and facilitates high-speed capturing by accurately determining focus lens positions based on peak evaluation values.
Implementation Method 1
an image pickup device for generating an image signal by converting image light incident through the focus lens to an electrical signal
Data Source
AI summary
Provided are a focusing apparatus for generating an image signal by converting image light incident through a focus lens to an electrical signal by an image pickup device, storing the image signal in a memory, calculating an AF evaluation value for an image signal read from the memory in a direction different from a reading direction of the image pickup device, and driving the focus lens by deriving a focus lens position corresponding to the calculated AF evaluation value, a focusing method thereof, and a recording medium for recording the focusing method. Accordingly, a focus can be correctly adjusted for various subject images, and a focus can be effectively adjusted for the images even in a high speed capturing mode.