Image Sensor Tilt Control Using Phase Difference Autofocus
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Solution Overview
Problem
Existing image capturing apparatuses struggle with slow calculation of tilt and focus positions, leading to degraded video quality and inability to handle high-resolution displays, especially when objects are not aligned with the camera's focus plane.
Innovation Solution
An image capturing apparatus utilizing on-imaging plane phase difference AF to calculate defocus amounts and tilt angles without moving lenses, enhancing ranging accuracy and improving focus control through pseudo baseline length extension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the lens and image sensor are actually moved to derive contrast evaluation values, then the tilt angle and focus position can be obtained, but the calculation time increases and video quality degrades
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing mapping relationships between defocus amounts and tilt angles in lookup tables during system initialization or idle periods. During actual video capture, the system queries these pre-computed tables based on current defocus measurements, eliminating the need for time-consuming real-time calculations while maintaining accurate focus positioning
Solution Approach 2:
The patent substitutes the mechanical approach of physically moving the lens and image sensor to measure contrast changes with an optical/electronic approach using phase difference detection pixels to measure defocus amounts directly. This replacement of mechanical movement with electronic measurement enables faster, more accurate focus detection without degrading video quality
2Measurement precision
If the lens and image sensor are reciprocating around in-focus position, then tilt angle can be calculated, but unnecessary operations are performed degrading video quality
Solution Approach 1:
The patent applies self-service by using the phase difference detection pixels integrated into the image sensor itself to directly measure defocus amounts without requiring external mechanical adjustment operations. The system leverages the sensor's own capabilities to provide focus information, eliminating unnecessary reciprocating operations that would degrade video quality while maintaining accurate tilt angle calculation
Solution Approach 2:
The patent introduces defocus amount as an intermediary parameter that mediates between the physical tilt state and the focus position. By measuring defocus amount through phase difference detection and using mapping relationships to derive tilt angles, the system avoids direct mechanical reciprocating operations while maintaining calculation accuracy
3Area of stationary object
If conventional focus control is used for objects not aligned with focus plane, then only partial region is in focus, but widening in-focus region requires additional tilt operations
Solution Approach 1:
The patent applies dynamics by implementing adaptive tilt control that dynamically adjusts the image sensor's orientation based on real-time defocus amount measurements and mapping relationships. The system continuously optimizes the tilt angle to maximize the in-focus region area, transforming a static focus system into a dynamic one that automatically adapts to different object positions and orientations
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
Achieves high-quality video capture by accurately determining tilt and focus positions, improving ranging accuracy, and reducing unnecessary operations, suitable for high-resolution displays.
Implementation Method 1
a deriving unit configured to derive, by a phase difference detection pixel included in the image sensor, a defocus amount with respect to an object image at a position of the phase difference detection pixel
Data Source
AI summary
An image capturing apparatus comprises: an image sensor for generating an image signal from an object image formed by an imaging optical system; a tilt control unit configured to execute tilt control of tilting the image sensor with respect to a principal surface of the imaging optical system; a deriving unit configured to derive, by a phase difference detection pixel included in the image sensor, a defocus amount with respect to an object image at a position of the phase difference detection pixel; and a control unit configured to control to execute the tilt control by the tilt control unit in deriving the defocus amount by the deriving unit, and to derive, by the deriving unit, a defocus amount based on an object image obtained while executing the tilt control.