Camera Controller Asynchronous Data Transfer
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Solution Overview
Problem
Existing camera systems face delays and reduced throughput in data communication between the camera body and interchangeable lens due to time-managed switching of communication masters, which increases power consumption and requires additional channels, especially when handling high frame rates and large data volumes.
Innovation Solution
The implementation of a three-channel communication system with a notification channel, a first data communication channel for accessory data, and a second data communication channel for camera data, allowing for asynchronous data transmission without the need for a separate BUSY signal channel, enabling high-speed data transfer without adding new channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If time-managed switching of communication master is implemented, then communication control between camera body and interchangeable lens is achieved, but communication delay increases and throughput decreases
Solution Approach 1:
The camera body transmits the next frame data in advance during the period when the interchangeable lens is outputting the BUSY signal. This preliminary transmission eliminates waiting time and ensures data is ready for immediate transfer once communication resumes, thereby reducing communication delay while maintaining control reliability.
Solution Approach 2:
The communication system eliminates idle periods by continuously utilizing the communication channel. While the interchangeable lens outputs BUSY signal, the camera body prepares and transmits next frame data, ensuring the communication channel remains productive throughout the entire cycle without interruption or waste of time.
2Productivity
If clock speed is increased to improve data transmission speed, then throughput increases, but communication delay increases significantly
Solution Approach 1:
Data is transmitted in advance during periods when the interchangeable lens is outputting BUSY signal, so that high-speed transmission occurs during productive periods rather than adding to delay-critical paths. This decouples transmission speed from delay accumulation.
Solution Approach 2:
The communication system uses periodic BUSY signal output from the interchangeable lens to create structured transmission windows. During these periodic BUSY periods, the camera body performs preliminary data transmission, creating a rhythm of communication that maximizes throughput while minimizing delay through predictable, periodic data flow patterns.
3Reliability
If BUSY signal channel is added to transmit communication suspension requests, then communication control reliability improves, but power consumption increases and device size increases
Solution Approach 1:
The notification channel serves multiple functions: it transmits both frame data and BUSY signals for communication suspension control. By merging these functions into a single channel, the system avoids the need for additional dedicated BUSY signal channels, thereby reducing power consumption and device size while maintaining full communication control reliability.
Solution Approach 2:
The notification channel is designed as a multi-functional channel that handles diverse communication tasks including data transmission, BUSY signal output, and communication suspension requests. This universal channel eliminates the need for specialized dedicated channels, reducing overall system complexity, power consumption, and device dimensions while preserving all necessary communication control capabilities.
Data Source
AI summary
The image-capturing apparatus includes a camera communicator to providing, with the accessory apparatus, three channels that are a notification channel, a first data communication channel used for transmitting accessory data from the accessory apparatus to the image-capturing apparatus, and a second data communication channel used for transmitting camera data from the image-capturing apparatus to the accessory apparatus. A camera controller is configured to, in response to detecting a start bit included in each of frames of the accessory data and indicating a start of each frame, transmit one frame of the camera data to the accessory apparatus through the second data communication channel and perform detection of the start bit regardless of whether or not during transmitting the camera data to the accessory apparatus.