Endoscope Light Source Control for Rolling Shutter Artifacts
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Solution Overview
Problem
Existing endoscope systems with rolling shutter type image sensors face issues of screen brightness unevenness and horizontal stripes due to differences in exposure time between frames, and offset light emission during the rolling shutter period can result in unnatural images.
Innovation Solution
A light source device with multiple semiconductor light emitting elements emitting different wavelength bands, controlled to have a strong and weak light emission period, with a restoration control process maintaining a constant total light emission amount, ensuring sufficient illumination while minimizing distortions and artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the light source is completely turned off during the rolling shutter period, then the rolling shutter distortions and artifacts are avoided, but the amount of light becomes insufficient and a satisfactory image cannot be acquired
Solution Approach 1:
The light source is controlled to emit light in periodic pulses during the rolling shutter period rather than being completely off. The control unit sets a pulsed light emission period within the rolling shutter period, allowing light to be emitted periodically to maintain sufficient illumination while avoiding continuous exposure that would cause rolling shutter artifacts.
Solution Approach 2:
The control unit performs preliminary determination of the pulsed light emission period based on the rolling shutter period before actual light emission occurs. This preliminary setup ensures that the light emission timing is optimized to provide sufficient light without causing the horizontal stripe artifacts that would result from improper timing.
2Illumination intensity
If a part of the rolling shutter period is included in the pulsed light emission period, then the insufficiency of light amount is solved, but screen brightness unevenness and horizontal stripes are caused by difference in exposure time between lines in adjacent frames
Solution Approach 1:
The control unit determines the pulsed light emission period based on feedback from the rolling shutter period timing. By synchronizing the light emission with the rolling shutter timing information, the system maintains consistent exposure across different lines while still providing sufficient light during the rolling shutter period.
Solution Approach 2:
The light emission profile is dynamically adjusted within the rolling shutter period. The control unit varies the light emission timing and duration based on the specific timing conditions of the rolling shutter, creating an adaptive emission pattern that maintains image uniformity while ensuring sufficient illumination.
3Illumination intensity
If offset light emission is performed during the rolling shutter period, then the insufficiency of light amount is solved, but an unnatural image is generated as if by double exposure of a long-time exposure image and a high-speed exposure image
Solution Approach 1:
The control unit changes the light emission parameters (timing, duration, intensity) to match the rolling shutter period characteristics. By synchronizing the light emission parameters with the rolling shutter timing rather than using independent offset emission, the system avoids the double exposure effect while still providing sufficient light.
Solution Approach 2:
The control unit performs preliminary determination of the light emission timing based on the rolling shutter period before actual emission occurs. This preliminary timing setup ensures that the light emission is coordinated with the rolling shutter operation, preventing the unnatural double exposure appearance while ensuring adequate illumination.
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
This solution ensures a sufficient light amount while reducing the occurrence of rolling shutter distortions and making brightness unevenness and horizontal stripes less noticeable, even with changes in pulsed light emission over the rolling shutter period.
Implementation Method 1
a plurality of semiconductor light emitting elements that emit light beams having different wavelength bands from each other
Data Source
AI summary
A light source device that generates illumination light, the light source device including: a plurality of semiconductor light emitting elements that emit light beams having different wavelength bands; and a control unit that controls a light emission profile of the plurality of semiconductor light emitting elements and drives the plurality of semiconductor light emitting elements, in which the light emission profile includes a strong light emission period in which light emission is performed with a predetermined light intensity and a weak light emission period in which light emission is performed with a light intensity weaker than the predetermined light intensity, and the control unit executes a restoration control process of converting into a light emission amount in the strong light emission period while maintaining a total amount of the light emission amount in the strong light emission period and the light emission amount in the weak light emission period constant.