Adaptive Focus Lens Driving Amount Control
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Solution Overview
Problem
Existing focus detection methods in digital cameras are hindered by light shielding issues with image pickup lenses, leading to increased errors and longer focusing times due to the need for repeated calculations and adjustments.
Innovation Solution
A focusing apparatus that includes a photoelectric converter and phase difference detector to calculate a driving amount for the focus lens based on phase difference detection results, allowing for adaptive lens movement to accelerate focusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If repeated focus detection calculations are performed to obtain reliable defocus amounts, then measurement precision is improved, but focusing time increases
Solution Approach 1:
The system performs preliminary focus detection at multiple positions during the focusing process and stores these detection results. When reliability determination is needed, the stored results from different positions are retrieved and used to determine reliability, avoiding the need to repeat all detection calculations from scratch.
Solution Approach 2:
The system uses feedback from multiple focus detection results at different lens positions to determine the reliability of the current defocus amount. By comparing detection results across different positions, the system can assess reliability and adjust the focusing process accordingly, reducing unnecessary repeated calculations.
2Measurement precision
If the lens driving amount is reduced to minimize detecting error influence, then measurement precision is improved, but focusing speed decreases
Solution Approach 1:
The system dynamically adjusts the lens driving amount based on the determined reliability of the defocus amount. When high reliability is confirmed through multi-position detection, the system can use larger driving amounts for faster focusing. When reliability is uncertain, smaller driving amounts are used to minimize error influence, creating a dynamic adaptation between speed and precision.
Solution Approach 2:
The system changes the lens driving amount parameter based on the reliability determination result. By modifying this critical parameter according to the reliability status, the system optimizes the balance between focusing speed and measurement precision in different operational contexts.
3Measurement precision
If focus detection continues until in-focus state is obtained, then measurement precision is improved, but focusing time increases
Solution Approach 1:
The system uses feedback from multiple focus detection results to determine reliability early in the focusing process. Once reliability is determined through comparison of detection results at different positions, the system can confidently proceed to in-focus state without continuing unnecessary detection iterations, thus reducing focusing time while maintaining precision.
Solution Approach 2:
The system performs preliminary reliability determination using stored detection results from different positions before continuing to in-focus state. This preliminary action allows the system to assess whether further detection is necessary, avoiding time-consuming continuous detection when reliability is already established.
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 reduces focusing time by determining the reliability of defocus amounts through multiple detections and adjusting the lens driving amount accordingly, enhancing the accuracy and speed of focus detection.
Implementation Method 1
a photoelectric converter configured to photoelectrically convert at least a pair of optical images formed by light fluxes that have passed a focus lens and to output at least a pair of image signals
Implementation Method 2
a phase difference detector configured to detect a phase difference between the pair of image signals output from the photoelectric converter
Data Source
AI summary
A focusing apparatus with a photoelectric converter which photoelectrically converts at least a pair of optical images formed by light fluxes that have passed a focus lens to output at least a pair of image signals, a phase difference detector which detects a phase difference between the pair of output image signals, and a driving amount calculator which calculates a driving amount of the focus lens based upon the detected phase difference. The driving amount calculator changes the calculated driving amount, in accordance with a first driving amount corresponding to a detected phase difference when the focus lens is located at a first position, a second driving amount corresponding to the detected phase difference when the focus lens is located at a second position, and a relationship between the first and second positions.