Flash Unit Light Emission Control via Relative GV Differences
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Solution Overview
Problem
Existing flash units struggle with optimal light emission control, particularly when using external flash units with cameras, as they rely on absolute GV values stored in memory, which do not account for variations in charged capacitor voltage, leading to inconsistent pre-flash and actual flash settings.
Innovation Solution
An external flash unit with a communication circuit, memory for light emission time data, and a controller that calculates light emission times based on input command values for pre-flash and actual flash, allowing for dynamic light emission control independent of capacitor voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a flash table of absolute GV values is used for light emission control, then the flash unit can operate with simple control logic, but the light emission amounts become inconsistent when capacitor voltage varies
Solution Approach 1:
The patent changes the control parameter from absolute GV values to relative GV value differences between pre-flash and actual flash. This allows the system to maintain simple control logic while achieving consistent light emission amounts by compensating for capacitor voltage variations through relative value comparison rather than absolute value lookup.
Solution Approach 2:
The patent introduces a feedback mechanism where the camera measures the actual pre-flash light amount received and communicates this information back to the flash unit. This feedback enables the flash unit to adjust the actual flash emission accordingly, ensuring consistent results despite variations in capacitor voltage or environmental conditions.
2Adaptability or versatility
If pre-flash and actual flash are controlled using separate absolute GV values, then each flash can be independently controlled, but the relationship between pre-flash and actual flash light amounts cannot be optimized
Solution Approach 1:
The patent transforms the control approach from independent absolute GV values to relative GV value differences. By storing and using the difference between pre-flash GV and actual flash GV in the flash table, the system maintains independent control capability while precisely optimizing the light amount relationship for various shooting conditions.
3Measurement precision
If the flash unit stores absolute GV values for every possible capacitor voltage, then accurate light emission control can be achieved for each voltage level, but the memory requirements and device complexity increase significantly
Solution Approach 1:
The patent reduces the data storage requirement by changing from storing absolute GV values for every capacitor voltage level to storing only relative GV value differences. This parameter transformation maintains light emission accuracy while dramatically reducing memory requirements and simplifying the data structure in the flash unit.
Data Source
AI summary
A flash unit capable of being attached to a flash control unit, comprising: a memory that stores information relating to a light emission time for actual flash corresponding to a difference between an emitted light amount command value for actual flash and an emitted light amount command value for pre-flash, and a controller, including an light emission time calculation section that obtains light emission time corresponding to emitted light amount command value for actual flash based on emitted light amount command value for pre-flash, emitted light amount command value for actual flash, and information stored in the memory, wherein the controller inputs the emitted light amount command value for pre-flash and the emitted light amount command value for actual flash acquired to the light emission time calculation section, and controls actual flash of the flash light emitting source based on the light emission time.