Imaging System Focus Control via Height-Specific Sensitivity Correction
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Solution Overview
Problem
Existing auto-focus control technologies in camera systems fail to accurately adjust focus sensitivity based on image height, leading to inadequate focus correction and increased communication data requirements, which complicates accurate focus control and data transmission between the camera body and lens unit.
Innovation Solution
The system includes a lens unit with a focus adjustment lens and a driving control unit, along with a communication unit that acquires and transmits focus detection signals and sensitivity correction information to the camera body, allowing for precise focus control by converting focus detection signals into driving amounts based on image height-specific conversion information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If focus sensitivity is determined based only on focal length information, then the focusing time is reduced, but the focus correction accuracy at surrounding image heights deteriorates
Solution Approach 1:
The patent applies local quality by providing different focus sensitivity values for different image height regions (center region vs. surrounding regions). The lens control unit stores multiple focus sensitivity values corresponding to different image heights and selects the appropriate value based on the detected image height, thereby achieving accurate focus correction for each specific region while maintaining efficient processing.
Solution Approach 2:
The patent segments the image height into multiple regions (center region and surrounding regions) and assigns different focus sensitivity characteristics to each segment. This segmentation allows the system to handle different focus requirements for different parts of the image independently, improving overall focus accuracy without requiring complete data for all regions simultaneously.
2Measurement precision
If different focus sensitivity data is transmitted for each image height, then the focus correction accuracy increases, but the communication data amount increases
Solution Approach 1:
Instead of transmitting complete focus sensitivity data for all image heights, the patent transmits only the necessary parameters (such as correction coefficients or representative values) that allow the lens control unit to calculate or select appropriate focus sensitivity values locally. This reduces communication data while maintaining the ability to provide accurate, region-specific focus correction.
Solution Approach 2:
The patent uses a simplified representation or model (such as correction coefficients or lookup tables) that can be transmitted efficiently and then expanded or calculated into complete focus sensitivity data at the lens control unit. This copying approach reduces the original data transmission requirement while preserving the ability to generate accurate focus sensitivity values for each image height region.
3Measurement precision
If focus sensitivity is varied for every image height, then the focus control accuracy improves, but the device complexity increases
Solution Approach 1:
The patent implements local quality by maintaining focus sensitivity information organized by image height regions in the lens control unit. When focus control is needed, the system detects the image height, selects or calculates the appropriate focus sensitivity value for that specific region, and applies it. This approach provides high-precision focus control for each region without requiring complex real-time calculations for every possible image height value.
Solution Approach 2:
The patent employs dynamic selection or calculation of focus sensitivity values based on the detected image height. Rather than using a single fixed value or pre-computing all possible values, the system dynamically determines the appropriate focus sensitivity at the time of focus control, adapting to the specific imaging conditions while maintaining computational efficiency.
Data Source
AI summary
An imaging system has an interchangeable lens and a camera body capable of communicating with the interchangeable lens. A camera control unit of the camera body acquires focus-sensitivity-related information (including sensitivity information at an image height of the center and correction information of the sensitivity that changes depending on the image height) from a lens control unit of the interchangeable lens through communication at a suitable timing. The camera control unit corrects a change of the sensitivity caused by the image height using image height information of a focus detection region selected from a plurality of focus detection regions and the acquired focus sensitivity correction information. The camera control unit calculates a driving amount of the focus lens from the focus detection signal using the corrected focus sensitivity, generates a control signal for instructing the driving amount, and transmits the control signal to a lens control unit.