Focus Detection Apparatus Threshold Correction Control
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Solution Overview
Problem
Conventional focus detection systems in single-lens reflex cameras face challenges in accurately detecting the in-focus position due to environmental and manufacturing errors, leading to potential degradation in focus adjustment precision during automatic focus adjustment.
Innovation Solution
A focus detection apparatus and control method that includes a focus detection unit, an obtaining unit for correction values, and a storage unit, where the correction value is only updated if the difference between the stored and obtained values exceeds a threshold, ensuring precise AF correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the correction value is updated frequently to improve focus adjustment precision, then measurement precision improves, but reliability deteriorates due to error propagation
Solution Approach 1:
The system implements feedback by comparing the newly obtained correction value with the stored correction value, and only updates when the difference exceeds a threshold. This feedback mechanism prevents erroneous updates while maintaining precision, resolving the contradiction between measurement precision and reliability.
Solution Approach 2:
The threshold value acts as a cushion against erroneous updates. By setting a threshold before update operations, the system prevents small erroneous corrections from degrading reliability, while still allowing significant valid corrections to improve precision.
2Adaptability or versatility
If the correction value is updated to reflect new measurements, then adaptability improves, but manufacturing precision deteriorates due to error accumulation
Solution Approach 1:
The feedback mechanism compares new correction values with stored values and only accepts updates when the difference exceeds the threshold. This ensures adaptability to genuine changes while filtering out erroneous variations, maintaining manufacturing precision.
Solution Approach 2:
The system dynamically adjusts the correction value only when necessary (when difference > threshold), rather than updating continuously. This dynamic approach allows adaptability when needed while preserving accuracy by avoiding unnecessary updates.
3Speed
If automatic focus adjustment is performed without correction, then operation speed improves, but measurement precision deteriorates due to environmental and manufacturing errors
Solution Approach 1:
The correction value is obtained and stored in advance through preliminary measurements. This preliminary action prepares the system with accurate correction data, enabling fast automatic focus adjustment without sacrificing precision due to environmental or manufacturing errors.
Solution Approach 2:
The system uses the stored correction value to self-correct focus measurements during automatic focus adjustment. This self-service mechanism maintains high measurement precision while keeping the operation speed fast, as no real-time complex calculations are needed during the actual focus adjustment.
Data Source
AI summary
A focus detection apparatus comprises: a focus detection unit configured to detect a focus state; an obtaining unit configured to obtain a correction value to be used in correction of the focus state detected by the focus detection unit; and a storage unit configured to store a correction value. In a case where a difference between the correction value stored in the storage unit and the correction value obtained by the obtaining unit is smaller than a threshold value, the correction value stored in the storage unit is not updated.