Focus Detection Baseline Adaptation for Camera Lenses
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Solution Overview
Problem
Existing focus detecting apparatuses for interchangeable lens cameras suffer from reduced accuracy due to the need to accommodate various aperture values, resulting in a short baseline between detecting elements, which deteriorates focus detection precision.
Innovation Solution
A focus detecting apparatus that dynamically selects pairs of detecting elements based on the F-value and light flux brightness of the optical system, adjusting the baseline length and number of elements to improve focus detection accuracy, and converts relative signal shifts into defocus amounts using a conversion factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the focus detecting apparatus is designed to be compatible with multiple interchangeable lenses having different aperture values, then the adaptability is improved, but the baseline length becomes small which deteriorates the measurement precision
Solution Approach 1:
The patent applies dynamics by making the selection of detecting elements dynamic rather than fixed. The focus detector dynamically selects different pairs of detecting element groups based on the actual aperture value and brightness conditions, allowing the baseline length to adapt to each shooting scenario. This resolves the contradiction by enabling the system to maintain long baseline for high aperture values (good precision) while still supporting low aperture values (good adaptability).
Solution Approach 2:
The patent changes the parameter of baseline length by selecting different detecting element pairs according to aperture value and brightness. When aperture value is large or brightness is high, elements farther apart are selected to maximize baseline length. When aperture value is small or brightness is low, elements closer together are selected. This parameter adaptation resolves the contradiction between adaptability and measurement precision.
2Device complexity
If a fixed pair of detecting element groups is used for all aperture values, then the device complexity is reduced, but the measurement precision deteriorates due to suboptimal baseline length
Solution Approach 1:
The patent introduces dynamic selection of detecting element pairs based on aperture value and brightness conditions. The focus detector evaluates current shooting conditions and selects the most appropriate pair of detecting element groups, making the system adaptive rather than fixed. This dynamic approach improves measurement precision without significantly increasing device complexity, as the selection logic is implemented through control unit programming.
Solution Approach 2:
The patent changes the operational parameters by selecting different detecting element pairs according to aperture value and brightness. This allows the baseline length parameter to be optimized for each shooting condition, improving focus detection accuracy while maintaining a relatively simple physical structure that only requires additive logic for element selection.
3Measurement precision
If detecting elements are selected based on aperture value and brightness, then the measurement precision is improved, but the device complexity increases due to additional selection logic
Solution Approach 1:
The patent implements dynamic selection of detecting elements based on real-time aperture value and brightness conditions. The focus detector continuously monitors these parameters and selects the most appropriate detecting element pair accordingly. This dynamic adaptation significantly improves measurement precision across varying shooting conditions while the added complexity is confined to the control logic, which can be implemented through software or firmware.
Solution Approach 2:
The patent changes the selection criteria for detecting elements based on aperture value and brightness parameters. By establishing clear selection rules that correlate these parameters with optimal detecting element pairs, the system achieves high measurement precision. The complexity increase is manageable as it involves primarily computational logic rather than additional hardware components.
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 approach enhances the accuracy of focus detection by optimizing the selection of detecting elements and baseline length in response to varying aperture values and light conditions, leading to improved precision in focus adjustment.
Implementation Method 1
a photo detector that has a plurality of detecting elements provided in correspondence with the micro lenses and receives light flux from an optical system via the micro lenses
Data Source
AI summary
Disclosed in a focus detecting apparatus comprising: a micro lens array arranged with a plurality of micro lenses, a photo detector that has a plurality of detecting elements provided in correspondence with the micro lenses and receives light flux from an optical system via the micro lenses; and a focus detector that selects a pair of groups of detecting elements from the plurality of detecting elements based on an F-value of the optical system and a brightness of the light flux from the optical system and detects a focus adjustment status of the optical system based on a pair of light receiving signals obtained in the groups of detecting elements.