Focus Detection Apparatus for Blinking Objects
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional contrast AF control methods struggle to accurately focus on blinking objects due to variations in luminance, leading to false detection of focus peaks and reduced AF accuracy.
Innovation Solution
An apparatus and method that determine if an object is blinking, perform filtering on the focus signal, and adjust the scan interval based on the reliability of detected peaks, ensuring accurate focus detection by widening the scan interval when reliability is low.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If contrast AF control is used to automatically focus on objects, then focusing automation is improved, but false focus detection occurs on blinking objects due to luminance variations
Solution Approach 1:
The system performs preliminary actions by detecting blinking patterns before final focus determination, and by pre-processing focus signals through filtering operations. The determination unit identifies blinking objects in advance, and the filtering process removes luminance-related noise before peak detection, preventing false focus locking on blinking objects.
Solution Approach 2:
A filtering process is introduced as an intermediary between focus signal acquisition and peak detection. This filter removes high-frequency components caused by blinking, acting as a mediator that separates useful focus information from harmful luminance variations. The filter transfer function is designed to pass low-frequency focus-related signals while attenuating high-frequency blinking-induced noise.
2Measurement precision
If exposure time is extended to reduce the influence of blinking, then blinking detection accuracy is improved, but object blur increases and AF accuracy is reduced
Solution Approach 1:
The system changes the parameter of scan interval dynamically based on blinking detection results. When blinking is detected, the scan interval is increased (scanning skips certain positions), which effectively reduces the impact of blinking on focus measurement without requiring extended exposure time. This parameter adjustment allows the system to maintain focus accuracy while accounting for blinking objects.
3Measurement precision
If the scan interval is widened to improve focus detection on blinking objects, then false focus detection is reduced, but focusing speed may be affected
Solution Approach 1:
The scan interval is made dynamic rather than fixed. The determination unit detects blinking in real-time and adjusts the scan interval accordingly - widening it when blinking is detected and maintaining normal intervals when no blinking is present. This dynamic adjustment optimizes both focus detection accuracy and focusing speed by adapting to the actual scene conditions.
Solution Approach 2:
Different scan intervals are applied to different regions or conditions locally. When blinking is detected in specific focus detection regions, the scan interval is widened only for those affected regions while maintaining normal scanning in unaffected areas. This localized quality adjustment preserves overall focusing speed while improving accuracy in problematic areas.
Data Source
AI summary
An apparatus that moves a focus lens, performs a scan operation of sequentially acquiring a focus signal, acquires a focus position of the focus lens based on the focus signal, and includes: a determination unit configured to determine whether an object is blinking at a predetermined period, and a processing unit configured to perform a filtering process in a time axis direction on the acquired focus signal where the object is blinking at the predetermined period.