CMOS Image Sensor Signal Synthesis for Endoscope Flicker Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Endoscope systems using intermittent illumination suffer from luminance unevenness due to varying exposure timing in CMOS image sensors employing the rolling shutter method, leading to flickering images when displayed.
Innovation Solution
A processing device synthesizes pixel signals from overlapping and non-overlapping illumination periods to generate a stable pixel signal, ensuring consistent brightness by overlapping read timings with illumination periods, using a signal processing unit to combine first and second pixel signals from a CMOS image sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If intermittent illumination is used to reduce energy consumption, then energy efficiency is improved, but luminance unevenness and flickering occur due to varying exposure timing
Solution Approach 1:
The patent applies dynamics by making the read timing of the image sensor variable rather than fixed. The read timing is dynamically adjusted to overlap with the illumination period of the pulsed light, allowing the system to adapt to intermittent illumination conditions. This dynamic timing adjustment ensures that all pixels receive light during their exposure period, eliminating luminance unevenness while maintaining energy efficiency through intermittent illumination.
Solution Approach 2:
The patent changes the timing parameter of the image sensor's read operation to optimize performance under intermittent illumination. By modifying the read timing to coincide with the illumination period, the system achieves uniform luminance across all pixels. This parameter change allows the system to maintain both energy efficiency (through pulsed illumination) and image quality (through uniform exposure).
2Speed
If rolling shutter method is used to read pixel signals, then reading speed is improved, but luminance unevenness occurs because exposure timing varies for each horizontal line
Solution Approach 1:
The patent makes the read timing dynamic by adjusting it to overlap with the illumination period. Instead of using fixed incremental timing for each horizontal line, the system dynamically synchronizes the read operation with the pulsed light timing. This ensures that all horizontal lines are read during the illumination period, eliminating luminance unevenness while maintaining the speed benefits of the rolling shutter method.
Solution Approach 2:
The system uses feedback by detecting the illumination timing of the pulsed light and adjusting the read timing accordingly. The image sensor's read operation is synchronized with the illumination period based on feedback about when the light is emitted. This feedback mechanism ensures that all pixels are read during the illumination period, achieving uniform luminance while maintaining high reading speed.
3Adaptability or versatility
If pulsed light timing does not align with image sensor read timing, then system flexibility is improved, but brightness variations and flickering occur
Solution Approach 1:
The patent applies dynamics by making the read timing adjustable rather than fixed. The system can dynamically change the read timing to match different pulsed light timing patterns, providing flexibility in adapting to various illumination schemes. This dynamic adjustment ensures that regardless of when the pulsed light is emitted, the read operation will overlap with the illumination period, maintaining brightness consistency.
Solution Approach 2:
The system performs preliminary action by detecting the illumination timing before the read operation begins. By knowing when the pulsed light will be emitted, the system can pre-adjust the read timing to ensure optimal overlap with the illumination period. This preliminary timing adjustment prevents brightness variations and flickering while maintaining the flexibility to adapt to different lighting conditions.
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 eliminates brightness variations between images, maintaining image quality and preventing flickering, even when the pulsed light timing does not align with the image sensor's read timing.
Implementation Method 1
a light receiving unit having a plurality of pixels that is configured to receive light from a subject illuminated with pulsed light and to generate a pixel signal
Data Source
AI summary
A processing device includes a signal processing unit configured to: input first and second pixel signals from an image sensor having pixels for receiving light from a subject illuminated with pulsed light and generating a pixel signal, the first pixel signal being a one-frame signal read at read timing at least a part of which is included in an illumination period of the pulsed light, the second pixel signal being a one-frame signal read after the one frame of the first pixel signal; and generate a one-frame third pixel signal by synthesizing first and second overlap pixel signals, the first overlap pixel signal being defined as the first pixel signal corresponding to an overlap line of the pixels in which the illumination period of the pulsed light is overlapped with the read timing, the second overlap pixel signal being defined as the second pixel signal corresponding to the overlap line.