Flash Control Device for Bulb Shooting Timing Synchronization

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Solution Overview

Problem

Conventional wireless flash control systems face challenges in achieving precise firing timing synchronization, especially during bulb shooting with indefinite exposure periods, due to delays in communication and inability to determine the end of exposure timing accurately, leading to inconsistencies between intended and actual exposure periods.

Innovation Solution

A flash control device and method that utilize a wireless communication interface and processors to repeatedly inform the flash of firing timing during the exposure period, stopping when the exposure condition is met, ensuring precise timing synchronization by continuously updating the firing timing until the exposure ends, allowing the rear curtain to close accurately.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If timing information is transmitted only once from the image capture apparatus to the wireless flash, then communication simplicity is maintained, but firing timing precision deteriorates due to communication delays and packet loss

Engineering Contradiction:

Improvecommunication protocol simplicityVSAvoidfiring timing precision

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The system transmits timing information multiple times before the actual flash firing to ensure the flash receives accurate timing data. By sending redundant timing packets in advance, the system compensates for potential communication delays or packet loss, ensuring the flash fires at the precise intended moment without requiring complex real-time adjustment mechanisms

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The flash acknowledges receipt of timing information by transmitting acknowledgment packets back to the image capture apparatus. This feedback mechanism allows the system to verify successful communication and adjust timing transmissions accordingly, ensuring precise firing timing while maintaining communication reliability

Inventive Principle:

Principle #23Feedback

2Reliability

If the flash receives timing information after the user operation ending the exposure period is detected, then communication reliability is improved, but firing timing precision deteriorates causing lag between intended and actual exposure period

Engineering Contradiction:

Improvecommunication reliabilityVSAvoidexposure timing lag

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system continuously transmits timing information during the entire exposure period rather than waiting until the exposure ends. This ensures the flash has the timing data well before it needs to fire, eliminating delays caused by waiting for confirmation of exposure end while maintaining communication reliability through redundant transmissions

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Timing information transmission continues throughout the exposure period rather than being a single discrete action. This continuous transmission ensures the flash always has up-to-date timing information, allowing immediate firing when needed without waiting for communication confirmation, thus eliminating exposure timing lag

Inventive Principle:

Principle #20Continuity of useful action

3Productivity

If transmission of timing information starts only when user operation ending exposure period is detected, then communication efficiency is improved, but firing timing precision deteriorates in bulb shooting mode

Engineering Contradiction:

Improvecommunication efficiencyVSAvoidfiring timing precision

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The system transmits timing information continuously during the exposure period in advance, so the flash is already prepared with the correct firing timing when needed. This eliminates the need for last-minute communication adjustments while maintaining efficient use of communication resources by only transmitting during active exposure periods

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The transmission strategy adapts to the exposure mode: in bulb shooting mode with indefinite exposure period, timing information is transmitted continuously during the exposure; in modes with determined shutter speed, transmission occurs at predetermined intervals. This dynamic approach optimizes both communication efficiency and firing timing precision for different shooting scenarios

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS10863070B2Flash control device, flash control method, flash, image capture apparatus, and image capture system

Publication Date: 2020.12.08 CANON KK

AI summary

A flash control device repeatedly informs a firing timing during an exposure period of the image capture apparatus. The device stops informing the firing timing if a condition for ending the exposure period of an image capture apparatus is satisfied. The disclosed flash control device can control the firing timing even in a case where a shooting mode of the image capture apparatus is a shooting mode with an indefinite exposure period.