Endoscope Rolling Shutter Exposure Uniformity Control
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Solution Overview
Problem
Endoscope apparatuses with CMOS image sensors using a rolling shutter scheme face exposure unevenness issues due to pulse illumination, leading to deterioration in image quality, as the light emission timing affects each line differently.
Innovation Solution
An endoscope apparatus with a light emitting section and an image pickup section using a rolling shutter scheme, along with an illumination control section that switches between two illumination patterns to control light emission during readout and exposure periods, and an electronic-shutter control section to perform electronic shutter processing, ensuring uniform exposure across all lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If pulse illumination is performed with a CMOS image sensor using a rolling shutter scheme, then the illumination efficiency is improved, but exposure unevenness occurs across different lines leading to image quality deterioration
Solution Approach 1:
The patent applies preliminary action by performing electronic shutter processing in the all-line exposure period before the readout period begins. This ensures that exposure is uniformly captured across all lines simultaneously, preventing exposure unevenness from occurring in the first place rather than correcting it afterward. The electronic shutter is activated at the timing when illumination pattern switching occurs, ensuring all lines start exposure at the same moment.
Solution Approach 2:
The patent implements dynamics by dynamically switching between two illumination patterns (first pattern with illumination during readout, second pattern without illumination during readout) and coordinating the electronic shutter timing with these pattern transitions. The illumination control section and electronic-shutter control section work together to adapt the exposure timing to the selected illumination pattern, maintaining exposure uniformity while allowing flexible illumination control.
2Speed
If exposure and readout are performed at different timing for each line in a rolling shutter scheme, then the readout speed is improved, but exposure unevenness occurs due to light emission timing differences
Solution Approach 1:
The patent applies preliminary action by performing electronic shutter processing in the all-line exposure period before the readout period begins. This ensures that exposure is uniformly captured across all lines simultaneously, preventing exposure unevenness from occurring in the first place rather than correcting it afterward. The electronic shutter is activated at the timing when illumination pattern switching occurs, ensuring all lines start exposure at the same moment.
Solution Approach 2:
The patent segments the operation into distinct periods: an all-line exposure period where exposure is performed simultaneously for all lines, and a readout period where data is read out line by line. By separating the exposure phase from the readout phase and applying electronic shutter control during the exposure period, the patent maintains exposure uniformity while preserving the speed benefits of sequential readout.
3Manufacturing precision
If correction processing is applied to eliminate exposure unevenness, then image quality is improved, but additional processing complexity is introduced
Solution Approach 1:
The patent applies preliminary action by performing electronic shutter processing in the all-line exposure period before the readout period begins. This ensures that exposure is uniformly captured across all lines simultaneously, preventing exposure unevenness from occurring in the first place rather than correcting it afterward. The electronic shutter is activated at the timing when illumination pattern switching occurs, ensuring all lines start exposure at the same moment.
Solution Approach 2:
The patent converts the potential harm of exposure unevenness into a benefit by using the all-line exposure period and electronic shutter control to prevent exposure unevenness from occurring in the first place. Instead of dealing with the negative effect of exposure differences, the system proactively ensures uniform exposure timing for all lines, turning a potential problem into a quality assurance mechanism.
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 effectively reduces luminance unevenness by synchronizing exposure and readout periods, preventing image quality deterioration and maintaining consistent brightness across the image frame without requiring high-speed or complex processing.
Implementation Method 1
an image pickup section of a rolling shutter scheme including a plurality of lines each including a plurality of pixels that receive light reflected from the subject illuminated by the light emitted by the light emitting section and generate an electric signal
Data Source
AI summary
An endoscope apparatus includes a light emitting element, an image pickup device of a rolling shutter scheme, and a control section. The control section performs control for switching between a first illumination mode for irradiating light on a subject in a readout period in which readout of an electric signal is performed in order for each of lines in the image pickup device and a second illumination mode for not irradiating light on the subject in the readout period. The control section controls the image pickup device to perform electronic shutter processing in all-line exposure period in which exposure of a plurality of lines is simultaneously performed in a frame corresponding to timing when one of the first illumination mode and the second illumination mode is switched to the other illumination mode.