Endoscope Illumination Controller Modulation for Rolling Shutter Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current imaging systems, particularly endoscope systems, face challenges in efficiently illuminating internal spaces that are difficult to reach with external light, leading to inadequate lighting for effective imaging due to the rolling shutter method used by CMOS image sensors, which results in uneven exposure and illumination.
Innovation Solution
The system incorporates an illumination controller that modulates the intensity of illumination light using a combination of pulses with varying intensities and output periods, ensuring a consistent light amount between pulses, thereby maintaining optimal illumination levels during both reading and non-reading periods of the CMOS image sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a rolling shutter scheme is used for reading pixel signals, then the device complexity is reduced and manufacturing is easier, but uneven exposure and illumination occur during imaging
Solution Approach 1:
The illumination light is emitted periodically in synchronization with the rolling shutter reading cycles. The light source turns on and off in regular intervals matching the line-by-line reading pattern, ensuring each scanned line receives appropriate illumination during its exposure window while maintaining manufacturing simplicity.
Solution Approach 2:
The illumination light is prepared and synchronized in advance with the rolling shutter reading timing. The system pre-coordinates the light emission timing with the expected line reading sequence, ensuring proper illumination is available before each line is scanned and read out.
2Illumination intensity
If illumination light is emitted continuously, then adequate lighting is provided for imaging, but energy consumption increases and brightness fringes occur
Solution Approach 1:
Instead of continuous illumination, the light source emits light periodically only during the intervals when lines are being read by the rolling shutter. This pulsed illumination pattern matches the active scanning periods, providing adequate lighting when needed while eliminating energy waste during non-reading periods and preventing brightness fringes.
Solution Approach 2:
The illumination is maintained continuously during the useful action periods (when lines are being read and exposed) while being interrupted during non-useful periods. This ensures uninterrupted lighting throughout the entire scanning cycle without creating gaps that would cause fringes, optimizing both energy efficiency and image quality.
3Use of energy by moving object
If pulse width modulation is used to control illumination, then energy efficiency improves, but illumination uniformity deteriorates due to timing misalignment
Solution Approach 1:
The illumination control system uses feedback from the rolling shutter reading status to adjust light emission timing. The controller monitors which lines are currently being read and adjusts the pulse width and timing of illumination accordingly, ensuring uniform exposure across all lines while optimizing energy consumption based on actual reading progress.
Solution Approach 2:
The illumination pulse width and timing are dynamically adjusted based on the real-time reading status of the rolling shutter. As different lines progress through the scanning process at different times, the system adapts the illumination parameters for each line's specific exposure window, maintaining uniformity while improving energy efficiency.
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 ensures consistent and efficient illumination, reducing the occurrence of bright and dark fringes in images, thereby enhancing the dynamic range of light control and improving image quality in challenging illumination conditions.
Implementation Method 1
an illumination portion configured to emit illumination light with which a main target is illuminated
Implementation Method 2
an imager including pixels two dimensionally arrayed and each configured to generate an electrical signal by photoelectrically converting received light
Data Source
AI summary
An imaging system includes an illumination portion, an imager, a reader, and an illumination controller configured to control an intensity of illumination light based on modulated illumination in a non-reading period. The modulated illumination has a first integrated light amount as a product of a variable intensity of a first pulse and an output period of the illumination light and a second integrated light amount as a product of a constant intensity of a second pulse and the output period. In the non-reading period, the illumination controller causes a predetermined light amount that is not larger than a maximum value of the first integrated light amount and is not smaller than a minimum value of the second integrated light amount to transit between the first integrated light amount and the second integrated light amount.