Imaging Device Focusing Control Using Pixel Correlation
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Solution Overview
Problem
Existing imaging devices face challenges in focusing control, particularly with low brightness or high frequency subjects, as they require phase difference detection pixels or contrast methods, which increase costs and can degrade image quality.
Innovation Solution
An imaging device with signal detection units arranged in two dimensions, using correlation values between detection signal groups to determine focus lens position without phase difference detection pixels or contrast methods, allowing for focusing control by moving the focus lens until it is determined to be in a focused state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If phase difference detection pixels are provided in the imaging element, then focusing speed is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent makes all imaging pixels serve dual functions: both capturing image data and performing phase difference detection for auto-focus. By processing detection signals from all pixels arranged in two dimensions, the system eliminates the need for dedicated phase difference detection pixels, reducing device complexity while maintaining fast focusing capability
Solution Approach 2:
The patent merges the functions of image capture and phase difference detection into a single pixel array. Instead of having separate pixel types for different functions, all imaging pixels contribute to both imaging and focus determination through correlation operations on their detection signals
2Speed
If phase difference detection pixels are provided in the imaging element, then focusing speed is improved, but manufacturing cost increases
Solution Approach 1:
The patent makes all imaging pixels serve dual functions: both capturing image data and performing phase difference detection for auto-focus. By processing detection signals from all pixels arranged in two dimensions, the system eliminates the need for dedicated phase difference detection pixels, reducing device complexity while maintaining fast focusing capability
Solution Approach 2:
The patent uses the existing imaging pixel array structure for dual purposes, avoiding the need to manufacture additional specialized pixels. The correlation operation on detection signals from standard imaging pixels creates a virtual phase difference detection system without requiring physical duplicate pixel structures
3Measurement precision
If the number of phase difference detection pixels increases, then focusing accuracy is improved, but image quality deteriorates due to increased correction marks
Solution Approach 1:
The patent makes all imaging pixels serve dual functions: both capturing image data and performing phase difference detection for auto-focus. By processing detection signals from all pixels arranged in two dimensions, the system eliminates the need for dedicated phase difference detection pixels, reducing device complexity while maintaining fast focusing capability
Solution Approach 2:
The patent merges the functions of image capture and phase difference detection into a single pixel array. Instead of having separate pixel types for different functions, all imaging pixels contribute to both imaging and focus determination through correlation operations on their detection signals
4Measurement precision
If contrast AF method is used to achieve high focusing accuracy, then focusing accuracy is improved, but focusing time increases due to wide range lens movement
Solution Approach 1:
The patent replaces the mechanical contrast-based focusing method (which requires physical lens movement across a wide range) with a signal processing approach. By performing correlation operations on detection signals from all pixels, the system determines focus position through computational analysis rather than extensive mechanical scanning, significantly reducing focusing time while maintaining accuracy
Solution Approach 2:
The patent performs correlation operations on detection signals from all pixels simultaneously across the imaging array, establishing focus determination capability without requiring sequential lens movement. This preliminary signal processing approach eliminates the need for time-consuming mechanical scanning while maintaining focusing accuracy
Data Source
AI summary
A digital camera includes an imaging element having an imaging surface where pixels are arranged in two dimensions in a row direction X and in a column direction Y, an AF processing unit that determines whether a focus lens is in a focused state using detection signals obtained from respective pixels of a first pixel group including plural pixels arranged in the row direction X and a second pixel group including pixels arranged at the same distance in one direction that crosses the row direction X with respect to each of the plural pixels of the first pixel group, in a state where the focus lens is at an arbitrary position, and a system control unit that moves the focus lens until the AF processing unit determines that the focus lens is in the focused state.