Live View Autofocus Timing Synchronization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In single-lens reflex cameras, it is challenging to accurately relate contrast values acquired during focus lens movement to the corresponding lens positions due to communication delays and the need for separate sensors for autofocus and exposure, which affects the precision of focus detection during live view functions.
Innovation Solution
An imaging apparatus with an image sensor, a first acquisition unit for contrast value measurement, and a second acquisition unit for lens position information at predetermined intervals, along with a focus detection unit that selects the appropriate lens position information to detect the focal position based on the contrast value, enabling accurate focus detection by interpolating between multiple lens position data points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the contrast method is used to perform AF operation using the image sensor during live view function, then the focus detection can be performed using the same sensor for both exposure and focus detection, but it becomes difficult to accurately relate the contrast value acquired at certain timing to the lens position at that timing due to communication delays and separate acquisition processes
Solution Approach 1:
The patent applies preliminary action by acquiring lens position information at predetermined time intervals before and during contrast value acquisition. This allows the system to have lens position data ready and available when contrast values are acquired, eliminating the timing synchronization problem. The lens position information is acquired in advance at multiple time points, ensuring that when a contrast value is acquired at any timing, the corresponding lens position information is already available in memory for accurate pairing.
2Device complexity
If lens position information is acquired at a single timing, then the data acquisition process is simple, but it is impossible to accurately match contrast values acquired at different timings with the correct lens position
Solution Approach 1:
The system acquires lens position information at predetermined time intervals in advance, creating a time-stamped record of lens positions. When a contrast value is subsequently acquired at any timing, the system can retrieve the lens position information that corresponds to the appropriate time interval, ensuring accurate matching without requiring complex real-time synchronization.
3Reliability
If separate sensors are used for AF operation and exposure, then each sensor can be optimized for its specific function, but the optical path must be divided and the AF sensor cannot receive light when the image sensor is exposed during live view function
Solution Approach 1:
The patent makes the image sensor multi-functional by using it for both exposure/image capture and focus detection during live view function. Instead of requiring a separate AF sensor, the system processes contrast values from the image sensor data that is already being captured for the live view display. This eliminates the need for separate AF sensor hardware and optical path division, allowing the same sensor to serve dual purposes.
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 allows for precise focus detection by accurately correlating contrast values with lens positions, reducing errors and enabling effective autofocus operations even during live view functions, thereby improving the camera's focus detection accuracy.
Implementation Method 1
an image sensor configured to generate an image signal by photoelectrically converting an object image
Data Source
AI summary
An imaging apparatus to which a lens apparatus is detachably attached includes an image sensor configured to generate an image signal by photoelectrically converting an object image, a first acquisition unit configured to acquire a contrast value of the image signal acquired by the image sensor, a second acquisition unit configured to acquire lens position information at a predetermined time interval, and a focus detection unit configured to detect a focal position based on outputs of the first acquisition unit and the second acquisition unit, wherein the focus detection unit selects the lens position information that corresponds to the contrast value acquired by the first acquisition unit from a plurality of pieces of the lens position information acquired by the second acquisition unit at the predetermined time interval, and detects the focal position.