Flash Control Method Using Preflash Feedback for Exposure Consistency
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Solution Overview
Problem
Conventional digital cameras face issues with flash precision and stability after repairs or replacements of flash-related components, or due to aging, leading to inconsistent lighting quality.
Innovation Solution
A flashing control method that determines main-flash intensity and sensitivity values using preflash brightness and pre-constructed tables to maintain consistent exposure, constructing energy and preflash tables to adjust main-flash indices for target brightness across different distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional flash control methods are used, then the flash can operate after component replacement or aging, but the precision and stability of flash output become worse
Solution Approach 1:
The patent implements a feedback mechanism where the camera measures the actual brightness output of the flash (through preflash testing and main flash measurement) and uses this information to automatically adjust future flash output. The system measures the reflected light from a preflash, calculates the actual flash strength, and compensates for deviations from the target brightness, thereby maintaining precision and stability even after component replacement or aging.
Solution Approach 2:
The patent dynamically adjusts flash output parameters (brightness, intensity) based on measured actual performance. By changing the flash output parameters adaptively according to measured values and pre-stored correction data, the system compensates for component degradation or replacement, maintaining consistent exposure results without requiring precise manual calibration.
2Adaptability or versatility
If flash intensity is manually adjusted, then different exposure settings can be achieved, but the complexity of operation increases
Solution Approach 1:
The patent enables the flash system to self-adjust and self-calibrate automatically. The camera performs preflash tests, measures actual brightness output, retrieves correction data from pre-stored tables, and automatically calculates the appropriate main flash intensity without requiring user intervention. This maintains exposure flexibility while eliminating manual adjustment complexity.
Solution Approach 2:
The patent performs preliminary calibration actions by pre-storing correction data in tables that map measured flash output to required compensation values. During actual shooting, the system simply looks up the pre-calculated correction data based on measured preflash brightness, avoiding the need for real-time complex calculations or manual adjustments while maintaining adaptability across different exposure settings.
3Measurement precision
If preflash brightness measurement is implemented, then accurate main-flash intensity can be determined, but the shooting time increases
Solution Approach 1:
The patent uses a partial action approach by implementing a brief preflash (shorter than the main flash duration) that provides sufficient information for measurement without requiring full flash intensity. The preflash is just enough to illuminate the scene for brightness measurement, and the actual main flash provides the required exposure. This partial preflash action achieves accurate measurement while minimizing time loss.
Solution Approach 2:
The patent rapidly executes the preflash and measurement process, skipping through the calibration steps quickly. The preflash duration is minimized to only what is necessary for measurement, and the system immediately proceeds to calculate and execute the main flash based on pre-stored correction tables, reducing the overall time penalty to nearly imperceptible levels.
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
Ensures consistent exposure and improved flash stability by adjusting main-flash intensity based on preflash brightness values and tables, maintaining target brightness values during picture capturing.
Implementation Method 1
a predetermined preflash is fired to obtain a corresponding preflash brightness value with respect to each distinct distance
Implementation Method 2
main-flash intensities are respectively obtained with respect to the sensitivity values such that their target brightness values are substantially the same after exposure
Data Source
AI summary
The present invention is directed to a flashing control method for a digital camera. Indices respectively corresponding to sensitivity values are firstly determined. Subsequently, main-flash intensities are respectively obtained with respect to the sensitivity values such that their target brightness values are substantially the same after exposure, thereby constructing an energy table. Further, a predetermined preflash is fired to obtain a corresponding preflash brightness value with respect to each distinct distance. Main-flash indices are then respectively obtained according to maximum main-flash intensity and the energy table with respect to the distinct distances such that the target brightness values are substantially the same after exposure, thereby constructing a preflash table. During picture capturing, the main-flash intensity is obtained according to the preflash brightness value and the preflash table.