Focus Control Device Using Dynamic Speed-Precision Switching
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Solution Overview
Problem
Existing auto-focus systems lack flexibility and precision in adjusting focus based on user preferences and subject characteristics, as they primarily rely on predefined movement directions and speeds without considering user manipulation or subject-specific conditions.
Innovation Solution
A focus control device that performs speed priority driving control when the defocus amount exceeds a threshold, and subject priority driving control when it is within the threshold, allowing for adjustable movement speeds and ranging area sizes based on user input and subject conditions, such as motion state and depth of field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If speed priority driving control is used to drive the focus lens quickly to the focusing position, then the focus adjustment speed is improved, but the focus precision and trackability deteriorate
Solution Approach 1:
The patent applies dynamics by switching between two driving patterns based on the defocus amount: speed priority driving pattern for large defocus amounts to achieve fast focus adjustment, and subject priority driving pattern for small defocus amounts to achieve precise focus positioning. This dynamic switching resolves the contradiction between speed and precision.
Solution Approach 2:
The patent changes the driving control parameters based on the defocus amount threshold. When the defocus amount exceeds the threshold, speed priority driving control is applied; when it is within the threshold, subject priority driving control is applied. This parameter change strategy enables the system to achieve both fast response and high precision.
2Measurement precision
If subject priority driving control is used to achieve precise focus positioning, then the focus precision is improved, but the focus adjustment speed deteriorates
Solution Approach 1:
The patent uses dynamic switching between driving patterns based on the defocus amount. Subject priority driving control is applied when the defocus amount is within the threshold for precise positioning, while speed priority driving control is used when the defocus amount exceeds the threshold for fast adjustment, resolving the speed-precision trade-off.
Solution Approach 2:
The patent segments the focus adjustment process into two stages based on the defocus amount threshold: the first stage uses speed priority driving for rapid coarse adjustment when defocus is large, and the second stage uses subject priority driving for precise fine adjustment when defocus is small, achieving both speed and precision.
3Adaptability or versatility
If the ranging area is set to a large size to improve subject detection, then the subject detection capability is improved, but the focus precision for specific subjects deteriorates
Solution Approach 1:
The patent dynamically adjusts the ranging area size based on the driving pattern: a first (larger) ranging area is used during speed priority driving to improve subject detection capability, while a second (smaller) ranging area is used during subject priority driving to improve focus precision on specific subjects, resolving the contradiction between detection capability and precision.
Data Source
AI summary
A focus driving control unit 34 of a control unit 30 performs speed priority driving control in which a focus lens is driven to a focusing position in a driving pattern selected in advance by a user, for example, in a case in which a defocus amount of a ranging area is greater than a driving control determination threshold set in advance. In addition, the focus driving control unit 34 performs subject priority driving control in which a focus lens movement amount by which the focus lens is located at the focusing position in accordance with the defocus amount of the ranging area is set and the focus lens is driven in a case in which the defocus amount is equal to or less than the driving control determination threshold. The focus lens is driven to the focusing position in the driving pattern selected by the user. Thereafter, a focusing state can be maintained. Accordingly, it is possible to easily perform an auto-focus operation with the high degree of freedom.