Image Sensor Region Accumulation Control for Focus Detection
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Solution Overview
Problem
Existing focus detection methods in image capturing apparatuses face challenges in achieving desired signal levels due to inconsistent accumulation control across image sensor regions, influenced by factors like region position, subject presence, and computation range.
Innovation Solution
An image capturing apparatus with a sensor capable of adjusting accumulation time for each region, utilizing a processor or circuit to control accumulation and calculate defocus amounts, allowing for adaptive focus detection based on the apparatus' state and settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the same accumulation control is always performed for each of the regions into which the image sensor has been divided, then the control method is simple, but it may not be possible to obtain a desired signal level, depending on conditions such as the position of the region in which the focus detection is performed, a computation range, whether or not a subject is present, and the like
Solution Approach 1:
The accumulation control is made dynamic by allowing the accumulation time to vary based on detection results. The system performs focus detection, evaluates signal levels, and adjusts accumulation time accordingly - transitioning from a static fixed accumulation time to a dynamic adaptive accumulation time that responds to actual imaging conditions
Solution Approach 2:
The system changes the accumulation time parameter based on detection results and imaging conditions. By monitoring signal levels and adjusting the accumulation time parameter upward or downward, the system adapts to different regions, subjects, and lighting conditions to achieve desired signal levels
2Measurement precision
If the accumulation time is extended to obtain a sufficient signal level, then the signal level improves, but the responsiveness of focus detection deteriorates
Solution Approach 1:
The accumulation time is dynamically adjusted based on detected signal levels rather than being fixed. When signal levels are insufficient, the accumulation time is extended; when signal levels are adequate, the accumulation time is kept shorter, thus maintaining responsiveness. This dynamic adjustment resolves the trade-off between signal level and responsiveness
Solution Approach 2:
The accumulation time parameter is changed adaptively based on signal level measurements. The system monitors signal levels and adjusts the accumulation time parameter in real-time, increasing it only when necessary to achieve sufficient signal levels, thereby maintaining fast responsiveness under normal conditions
Data Source
AI summary
An image capturing apparatus capable of focus detection includes a sensor including a plurality of pixels, the sensor being capable of changing an accumulation time of the pixels for each of a plurality of regions including the plurality of pixels, an accumulation control unit that, in accordance with a state or a setting of the image capturing apparatus, changes accumulation control of the pixels for each of the plurality of regions, and a defocus computation unit that calculates a defocus amount using signals from the pixels for which accumulation has been controlled by the accumulation control unit.