Electronic Endoscope Rolling Shutter Synchronization
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Solution Overview
Problem
CMOS image sensors in electronic endoscope systems face challenges in capturing successive images under different illumination conditions due to their rolling shutter technique, which causes exposure timing differences between horizontal lines, making it difficult to obtain images with consistent illumination.
Innovation Solution
The system employs a CMOS image sensor with a light source device that turns on and off repeatedly, switching between illumination wavebands, and a signal processor that reads image signals while the light is off, synchronizing exposure timing and preventing rolling shutter artifacts without a mechanical shutter, allowing for consecutive image capture under varying illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If the rolling shutter technique is used in CMOS image sensor, then power consumption is reduced and integration is simplified, but exposure timing differs between horizontal lines causing image deformation in moving objects
Solution Approach 1:
The patent applies periodic action by switching the illumination light source on and off at specific intervals synchronized with the rolling shutter exposure. The light source is turned on during the exposure period and turned off during the readout period, creating a periodic cycle that ensures all horizontal lines are illuminated under the same wavelength conditions despite different exposure timings, thereby preventing image deformation while maintaining power efficiency
2Productivity
If the wavelength of illumination light is changed at frame rate, then successive images under different illumination conditions can be obtained with CCD sensor, but with CMOS sensor the last horizontal line is exposed after wavelength change causing inconsistent illumination conditions within each frame
Solution Approach 1:
The patent applies preliminary action by changing the illumination light wavelength during the readout period before the next exposure begins. This ensures that when exposure starts for all horizontal lines, the wavelength has already been switched to the desired value for the next frame, allowing successive frames to be captured under different illumination conditions while maintaining consistency within each frame
Solution Approach 2:
The patent applies dynamics by dynamically adjusting the illumination wavelength timing to match the rolling shutter operation. Instead of changing wavelength at fixed frame intervals, the system dynamically synchronizes wavelength changes with the rolling shutter's exposure and readout cycles, allowing flexible switching between different illumination conditions while maintaining image quality
3Stability of the object's composition
If illumination light is continuously on, then all horizontal lines are exposed under same illumination conditions, but cannot capture successive images under different illumination conditions
Solution Approach 1:
The patent applies periodic action by switching the illumination light source on and off in synchronization with the rolling shutter operation. The light is turned on during exposure and turned off during readout, creating periodic cycles that allow wavelength changes between frames while ensuring all lines in each frame are exposed under consistent illumination conditions
Solution Approach 2:
The patent applies continuity of useful action by ensuring that the illumination light is always on during the exposure period for all horizontal lines, even though the overall cycle includes off periods during readout. This continuous illumination during exposure ensures consistency across all lines while the periodic off periods enable wavelength switching between frames
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 approach enables the production of high-quality, successive images under different illumination conditions, simplifying the endoscope's structure and improving diagnostic capabilities by preventing image deformation and allowing for convenient operation and display of dual images.
Implementation Method 1
a CMOS image sensor having a plurality of pixels in a two dimensional array which captures an image of a region of interest under illumination light and generates image signals
Data Source
AI summary
An electronic endoscope system includes an electronic endoscope having a CMOS image sensor on the tip of an insertion section, a light source device for illuminating the interior of a patient's body, and a processing device for reading out image signals from the CMOS image sensor. The electronic endoscope system can operate with a standard imaging mode and a special imaging mode. When the time taken to read out the image signals from all the pixels in the standard mode is defined as T, the light source device in the special imaging mode emits illumination light in every first half period T/2 while switching a wavelength of the illumination light between two different wavebands. In every second half period T/2, the processing device reads out the image signals from the half of the pixels.