Interchangeable Lens Synchronization Protocol for TVAF Control
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Solution Overview
Problem
In lens interchangeable camera systems, the varying optical characteristics of each interchangeable lens make it difficult to provide effective contrast type autofocus (TVAF) control, and existing communication methods can lead to synchronization issues and inaccurate lens control due to lowered communication speed and random timing.
Innovation Solution
The camera system employs a synchronized communication protocol between the lens microcomputer and the camera microcomputer, using fixed-length packet communication synchronized with a vertical synchronizing signal, which includes specific standby time periods to ensure accurate and reliable focus lens control, preventing communication and actuator control losses across different lens types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a lens interchangeable camera system uses conventional TVAF control with variable communication timing, then the system can accommodate different interchangeable lenses with varying optical characteristics, but the communication speed decreases and synchronization is lost leading to inaccurate lens control
Solution Approach 1:
The patent applies periodic action by synchronizing communication with the vertical synchronizing signal (VSYNC) which occurs at fixed periodic intervals. The communication timing is determined by the formula: communication timing = VSYNC timing + (n × VSYNC period) + offset, where n is an integer and offset is a fixed value. This ensures that communication occurs at regular, predictable intervals aligned with the camera's vertical scan rate, maintaining synchronization while accommodating different lens types.
Solution Approach 2:
The patent implements dynamics by allowing the communication protocol to adapt to different lens characteristics while maintaining a fixed synchronization framework. The system dynamically adjusts the communication parameters (such as the number of VSYNC periods n and the offset) based on the specific lens attached, enabling the same communication structure to work with various lenses having different optical properties, response times, and processing capabilities.
2Device complexity
If the communication timing is set randomly or with variable intervals, then the system can be simpler to implement, but the focus control becomes inaccurate due to lost synchronization with the vertical synchronizing signal
Solution Approach 1:
The patent uses periodic action by tying communication events to the periodic vertical synchronizing signal. Instead of random or variable timing, communication occurs at predetermined intervals defined by multiples of the VSYNC period plus a fixed offset. This creates a regular, predictable communication rhythm that maintains synchronization while keeping the protocol relatively simple to implement.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and setting the communication timing parameters (n and offset values) before actual communication occurs. The system determines the appropriate communication timing in advance based on the lens characteristics and camera settings, then executes communication at these predetermined moments, ensuring synchronization without requiring complex real-time adjustments.
3Speed
If the communication speed is increased to improve responsiveness, then the focus adjustment can be faster, but the synchronization with the vertical synchronizing signal is lost causing control errors
Solution Approach 1:
The patent resolves this contradiction by using periodic action aligned with the camera's vertical synchronizing signal. Communication occurs at fixed intervals determined by the VSYNC period, ensuring that speed increases do not compromise synchronization. The system can process and transmit data faster within each communication window while maintaining the overall periodic rhythm that keeps it synchronized with the vertical scan.
Solution Approach 2:
The patent maintains continuity of useful action by ensuring that communication and focus control operations continue without interruption or desynchronization. By anchoring communication to the continuous vertical synchronizing signal, the system ensures uninterrupted, synchronized operation even at higher speeds, preventing control errors while maintaining responsive focus adjustment.
Data Source
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AI summary
A lens apparatus is detachable from an image pickup apparatus. The lens apparatus includes a controller configured to communicate with the image pickup apparatus in synchronization with a first signal. A communication contains a plurality of blocks in the same cycle of the first signal. The controller transmits information of a first time period to the image pickup apparatus, and prohibits a communication of an m-th block from starting before the first time period passes after a communication of an n-th block starts or ends where n is an integer equal to or larger than 1 and m is an integer larger than n.