Image-Capturing Apparatus Focus Lens Velocity Control
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Solution Overview
Problem
Existing image-capturing apparatuses face challenges in accurately and efficiently performing auto-focus control, especially when objects are moving, as they rely on methods that require multiple exposures and complex calculations to determine object distance and focus position.
Innovation Solution
An image-capturing apparatus with a focus lens and image sensor that detects distance changes during a preliminary exposure period, determines a control amount for moving the focal position during a main exposure period, and adjusts the focus lens velocity to maintain object focus, utilizing Depth From Defocus (DFD) calculations and point spread functions to produce images with varying defocusing amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple exposures are used to determine object distance, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent performs distance measurement during a preliminary exposure period before the main exposure. By detecting distance changes during the first exposure period and determining control amounts beforehand, the system prepares focus control parameters in advance, reducing the time required during the actual image capture while maintaining measurement precision through the preliminary depth from defocus calculations.
2Manufacturing precision
If complex calculations are performed to determine focus position, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts and utilizes the depth from defocus information that is already present in the captured images. By calculating object distance based on defocus amounts from multiple images taken during the preliminary exposure, and deriving focus control amounts from these extracted depth measurements, the system achieves accurate focus positioning without requiring additional complex hardware or calculation systems.
3Reliability
If focus control is adjusted for moving objects, then reliability is improved, but ease of operation worsens
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously detects distance changes during the preliminary exposure period, determines appropriate control amounts based on detected object motion, and adjusts the focal position accordingly during the main exposure. This automatic feedback-based adjustment ensures reliable focus tracking for moving objects while eliminating the need for manual operation adjustments.
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 solution enables convenient and accurate focusing on moving objects by estimating object velocity and adjusting focus lens movement, ensuring in-focus images are captured during the main exposure period, even when objects change distance along the Z-axis.
Implementation Method 1
an image sensor that produces image data by capturing the object image
Implementation Method 2
a focus lens that forms an object image of the object; The focus lens has a focal position
Data Source
AI summary
An image-capturing apparatus includes a focus lens that forms an object image of the object, an image sensor that produces image data by capturing the object image, and a controller that controls the focus lens. The focus lens has a focal position. The controller is operable to detect a change of a distance from the image-capturing apparatus to the object during a first exposure period based on image data produced by capturing the object image with the image sensor during the first exposure period. The controller is operable to determine, based on the detected change in the distance, a control amount which controls a moving velocity at which the focal position moves during a second exposure period after the first exposure period. The controller is operable to move the focal position at a moving velocity corresponding to the determined control amount, and cause the image sensor to capture the object image during the second exposure period.