Electronic Still Camera Flicker Exposure Timing Control
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Solution Overview
Problem
Conventional image capturing apparatuses face challenges in obtaining correct exposure when photographing under illumination light with flicker, as the exposure time can result in insufficient luminance due to mismatched timing with the flicker interval, leading to either insufficient or excessive inclusion of minimum and maximum illuminance values during the exposure period.
Innovation Solution
An electronic still camera equipped with a flicker detection device and an image capturing timing adjustment device that adjusts the exposure time to coincide with the maximum illuminance period or set it to a natural multiple of the flicker interval, ensuring correct exposure by sequentially capturing and composing images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the exposure time is set to coincide with the maximum illuminance phase of flickering light, then the luminance of the captured image is improved, but the exposure time may become longer than the flicker interval causing inconsistent inclusion of maximum and minimum illuminance values
Solution Approach 1:
The patent applies periodic action by synchronizing the exposure timing with the periodic flicker cycle of illumination light. The exposure timing is adjusted so that the exposure period corresponds to the flicker interval, ensuring that maximum illuminance values are consistently captured while minimum values are excluded, thereby achieving stable and correct exposure under flickering light conditions.
Solution Approach 2:
The patent changes the exposure time parameter to be equal to or longer than the flicker interval of the illumination light. This parameter adjustment allows the exposure to span complete flicker cycles, ensuring that only maximum illuminance phases are captured, thereby resolving the exposure inconsistency caused by mismatched timing between exposure and flicker periods.
2Reliability
If sequential shooting is performed to suppress camera shake, then image quality is improved, but the accumulation time increases making the system more susceptible to flicker effects
Solution Approach 1:
The patent applies periodic action by synchronizing the sequential shooting accumulation time with the periodic flicker interval of the illumination light. By setting the accumulation time to match the flicker period, the system ensures that each captured frame corresponds to the maximum illuminance phase, thereby maintaining high image quality while preventing flicker artifacts in the composite image.
Solution Approach 2:
The patent uses feedback by detecting the flicker characteristics of the illumination light and adjusting the exposure timing and accumulation time accordingly. The system monitors the flicker interval and uses this information to optimize the sequential shooting parameters, ensuring that the accumulation time is sufficient to capture multiple maximum illuminance phases while excluding minimum phases, thereby maintaining image quality under flickering conditions.
Data Source
AI summary
An object of this invention is to suppress both the influence of a change in image quality by flicker and the influence of degradation of the image quality by a camera shake when an electronic still camera takes a picture under illumination having flicker. In an electronic still camera which captures a plurality of low-luminance images and composites them into one image of correct exposure, when the exposure time is shorter than the flicker interval of illumination light, the center of the exposure time is made to substantially coincide with the maximum value of the light quantity of illumination light. When the exposure time is longer than the flicker interval of illumination light, the exposure time is set again to a natural number multiple of the flicker interval.