Endoscope Oxygen Saturation Imaging Frame Rate
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Solution Overview
Problem
Conventional endoscope systems experience a decrease in frame rate, brightness, and resolution when switching between normal and special observation modes, particularly in the special observation mode for oxygen saturation level measurement, due to the rolling shutter method and reduced exposure times.
Innovation Solution
The endoscope system employs a global shutter method for the special observation mode, with pixel groups of different spectral sensitivities and increased clock frequencies to reduce read times, and selectively reads signals from the most sensitive pixels, maintaining frame rate without compromising image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a turn-off period is provided upon switching between normal light and special light, then the mixing of light in image capture is prevented, but the frame rate of the image sensor decreases
Solution Approach 1:
The patent employs periodic switching between normal light and special light illumination, with each illumination type being activated in alternating cycles. This periodic action allows the image sensor to capture images during specific time windows corresponding to each light type, ensuring that no mixing occurs while maintaining a sustained overall frame rate by efficiently utilizing the periodic illumination pattern.
Solution Approach 2:
The patent dynamically adjusts the exposure time parameter of the image sensor to match the timing of light switching. By changing the exposure time parameter and synchronizing it with the illumination switching, the system captures images only during the intended light illumination periods, preventing light mixing while optimizing the frame rate by minimizing unnecessary turn-off periods.
2Productivity
If emission time and read time are reduced to prevent frame rate decrease, then brightness and resolution of the images decrease
Solution Approach 1:
The patent performs preliminary synchronization of the image sensor's exposure timing with the light switching sequence before actual image capture begins. By pre-configuring the exposure start and end times to align perfectly with the illumination periods, the system maximizes the effective exposure time within each frame cycle, ensuring sufficient light capture for bright images while maintaining the required frame rate.
Solution Approach 2:
The patent maintains continuous useful action by ensuring that the image sensor is always exposed during the illumination periods without unnecessary interruptions. The exposure timing is continuously synchronized with the light switching, eliminating wasted time between exposures and maintaining both high frame rate and sufficient brightness by keeping the sensor actively capturing during all useful illumination windows.
3Ease of manufacture
If the rolling shutter method is used, then power consumption is reduced and peripheral circuits can be integrated, but exposure timing shifts cause light mixing when illumination is switched
Solution Approach 1:
The patent implements a feedback mechanism where the light switching signal is used to control and adjust the exposure timing of the rolling shutter image sensor. The system monitors the illumination switching state and provides feedback to the sensor control circuitry, dynamically adjusting the exposure start and end times for each row to ensure they coincide with the active illumination periods, thereby preventing light mixing while maintaining the benefits of the rolling shutter method.
Solution Approach 2:
The patent introduces dynamic timing adjustment to the rolling shutter method, where the exposure timing for each pixel row is dynamically modified based on the light switching state. Instead of using fixed exposure timing, the system adapts the exposure windows dynamically to match the illumination cycles, allowing the rolling shutter to function effectively in switched illumination conditions without light mixing.
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 prevents a decrease in frame rate and maintains the brightness and resolution of oxygen saturation images, ensuring accurate diagnosis by minimizing the mixing of normal and special light exposure periods.
Implementation Method 1
an image sensor that captures, via the lens, images of reflection light from the observation region and outputs an image capture signal
Data Source
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AI summary
There are provided an endoscope system, a processor apparatus for an endoscope system, and a method for operating an endoscope system with which a decrease in the frame rate can be suppressed without a decrease in the brightness and resolution of an oxygen saturation image. In a special observation mode, first illumination light and second illumination light having a spectral property different from a spectral property of the first illumination light and including different-absorption-wavelength light that has different absorption coefficients for oxygenated hemoglobin and reduced hemoglobin are alternately emitted to a test body while a turn-off period is interposed, and an image is captured by a CMOS image sensor. A first image capture signal is read from the image sensor during the turn-off period after emission of the first illumination light, and a second image capture signal is read from the image sensor during the turn-off period after emission of the second illumination light. Here, a second read time taken to read the second image capture signal is made shorter than a first read time taken to read the first image capture signal. An oxygen saturation image is generated on the basis of the first and second image capture signals read from the image sensor.