Imaging Device Dynamic Shift Limit for Phase Difference AF
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Solution Overview
Problem
Existing phase difference AF methods in imaging devices perform redundant operations, leading to inefficient focus control, as the value of L is set constant regardless of the subject's blur state, resulting in unnecessary correlation operations and reduced speed.
Innovation Solution
An imaging device with a defocus amount calculating unit that sets an upper limit for signal shifts based on the F value, focal distance, and focus lens position, adjusting this limit according to changing imaging conditions to optimize phase difference AF operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the value of L is set constant regardless of the subject's blur state, then the phase difference AF can be performed with a fixed operation range, but redundant correlation operations are performed leading to reduced processing speed
Solution Approach 1:
The patent applies dynamics by making the value of L variable rather than constant. The defocus amount calculating unit dynamically adjusts L based on the detected blur state of the subject. When the subject is significantly blurred, a larger L value is used to capture more phase difference information, while when the subject is slightly blurred, a smaller L value is used to reduce redundant calculations, thereby optimizing processing speed adaptively
Solution Approach 2:
The patent changes the parameter L (shift amount) based on the blur state of the subject. By detecting the degree of blur and adjusting L accordingly, the system performs correlation operations only over the necessary range, eliminating redundant operations and improving processing efficiency without sacrificing focus accuracy
2Ease of operation
If the upper limit of shifted amount is fixed, then the correlation operation range is predetermined, but unnecessary operations are performed when imaging conditions change
Solution Approach 1:
The system dynamically adjusts the upper limit of the shifted amount based on imaging conditions such as F value, focal distance, and focus lens position. This dynamic adjustment allows the correlation operation to cover only the necessary range for the current imaging scenario, eliminating unnecessary computations while maintaining operational simplicity through automated adaptation
Solution Approach 2:
The patent changes the upper limit parameter of the shifted amount according to varying imaging conditions. By linking this parameter to actual optical parameters (F value, focal distance, lens position), the system automatically optimizes the correlation operation range, improving focus control efficiency without complicating the operation process
Data Source
AI summary
An imaging element 5 includes an imaging pixel 51 and phase difference detecting pixels 51R and 51L. When there is an instruction to start capturing a moving image, a defocus amount calculating unit 19 determines a shift amount of two output signal groups at the time of performing a correlation operation in accordance with information of an F value, a focal distance, and a focal position. The defocus amount calculating unit 19 shifts two output signal groups by a unit amount within a range of a determined shift amount to perform a correlation operation and calculates a defocus amount from the result. Thereafter, when the distance to a major subject varies, the defocus amount calculating unit changes the shift amount which has been already set to a larger value.