Camera Tilt-Focus Control for Accurate Depth-of-Field Adjustment
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Solution Overview
Problem
Existing image pickup apparatuses struggle with inaccurate and slow tilt control due to errors in tilt angle, focus position stopping accuracy, hysteresis variations, and external disturbances, which hinder the achievement of a deep depth of field in imaging scenes.
Innovation Solution
A control apparatus and method that utilizes an in-focus evaluation value calculator to determine the optimal tilt and focus adjustments by analyzing contrast and luminance values, and a tilt/focus determining unit to drive the image sensor or focus lens accordingly, ensuring accurate and fast tilt control based on the Scheimpflug principle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If automatic tilt control is performed based on pre-stored tilt angle and focus position information, then the control process is simple, but the tilt control accuracy deteriorates due to errors in tilt angle, stopping accuracy of focus position, hysteresis variations, and external disturbances
Solution Approach 1:
The patent implements feedback by detecting the actual tilt angle and focus position after the tilt control is executed, comparing these actual values with the pre-stored target values, and using the difference (error signal) to correct subsequent control operations. This closed-loop feedback mechanism continuously improves tilt control accuracy by compensating for errors in the pre-stored information and external disturbances.
Solution Approach 2:
The patent replaces the purely mechanical/pre-stored control system with an optical measurement system. Instead of relying solely on pre-stored tilt angle and focus position information, the system uses an optical system to detect the actual tilt angle and focus position, substituting mechanical measurement with optical detection to achieve higher precision and eliminate errors from mechanical hysteresis and external disturbances.
2Speed
If tilt control is performed without considering actual focus detection results, then the control speed is fast, but the tilt control accuracy deteriorates due to errors in focus position and external disturbances
Solution Approach 1:
The patent performs preliminary actions by pre-storing target tilt angle and focus position information before the actual tilt control is needed. This pre-prepared information allows the system to execute tilt control quickly without delay, while the actual focus detection results are then used to correct and refine the control accuracy, combining speed of preliminary action with precision of actual measurement.
Solution Approach 2:
The system uses feedback from actual focus detection results to correct the tilt control. The detected actual focus position and tilt angle are compared with the pre-stored target values, and the difference is used to adjust subsequent control operations, thereby maintaining both fast control speed and high accuracy through the feedback mechanism.
3Adaptability or versatility
If the image sensor or optical system is tilted to achieve deep depth of field, then the depth of field is extended, but the focus accuracy deteriorates due to mechanical errors and external disturbances
Solution Approach 1:
The patent implements feedback by detecting the actual tilt angle and focus position after tilting the image sensor or optical system, comparing these actual values with the target values, and using the difference to correct subsequent focusing operations. This closed-loop feedback ensures that focus accuracy is maintained even when the system is tilted to extend the depth of field, compensating for mechanical errors and external disturbances.
Solution Approach 2:
The patent changes parameters by dynamically adjusting the tilt angle and focus position based on actual detection results. Instead of using fixed pre-stored values, the system modifies these parameters in real-time according to the actual focus detection and tilt angle measurement, allowing the system to adapt to mechanical errors and external disturbances while maintaining both extended depth of field and accurate focusing.
Data Source
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AI summary
A control apparatus includes a controlling unit configured to control tilt driving for tilting at least one of an image sensor and an imaging optical system relative to a plane orthogonal to an optical axis and focus driving for moving a focus lens in an optical axis direction, an acquiring unit configured to acquire focus levels in a first area and a second area in an image captured by an image pickup apparatus, a first determining unit configured to determine whether to perform the tilt driving or the focus driving, based on an in-focus level, and a second determining unit configured to determine a driving direction of the tilt driving or the focus driving based on the in-focus level.