Endoscope Synchronization for Uniform Image Luminance
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Solution Overview
Problem
In endoscope systems, a mismatch between light adjustment timing and image reading timing leads to luminance differences in captured images, especially in low-luminance modes, causing variability in image quality.
Innovation Solution
The endoscope system generates a second vertical synchronization signal based on a first vertical synchronization signal and exposure timing to control the timing of image reading, ensuring that image data is read during periods when the illuminator is off, thereby equalizing exposure amounts across horizontal lines and preventing luminance differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If PWM light adjustment is performed during blank period of imaging element, then luminance of illumination light can be adjusted, but luminance differences occur in captured images due to timing mismatch between light adjustment and image reading
Solution Approach 1:
The system performs preliminary action by adjusting the illumination light intensity before the imaging element reads the image data. The light source device executes PWM light adjustment during the blank period of the imaging element, which occurs before the actual image capture phase, thereby preparing the appropriate illumination conditions in advance for consistent image quality
Solution Approach 2:
The system implements feedback by using the vertical synchronization signal to coordinate the timing between the light source device and the imaging element. The processor outputs the vertical synchronization signal to both the endoscope and the light source device, creating a closed-loop timing mechanism that ensures the light adjustment timing is synchronized with the image reading timing, thereby eliminating luminance differences
2Productivity
If light source device executes PWM light adjustment during blank period, then image reading timing can be controlled, but luminance differences still occur due to exposure timing variations across horizontal lines
Solution Approach 1:
The system performs preliminary action by completing all illumination adjustments during the blank period before any image data is read. The light source device adjusts the illumination intensity for the entire frame during this preliminary phase, ensuring that when the imaging element subsequently reads the image data, the exposure conditions are already optimized and uniform across all horizontal lines
Solution Approach 2:
The system employs periodic action through the vertical synchronization signal that periodically triggers both the PWM light adjustment and the image reading operations. This periodic synchronization ensures that the illumination light adjustment and image capture occur in coordinated cycles, maintaining consistent exposure timing and eliminating luminance variations across different horizontal lines
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 image quality by eliminating luminance differences in both low- and high-luminance modes, regardless of the processor type connected, and allows for appropriate image processing and transmission.
Implementation Method 1
an imaging element including a light receiver where multiple pixels configured to receive light and perform photoelectric conversion to generate electric signals are arranged in a two-dimensional matrix
Data Source
AI summary
An endoscope includes: an illuminator configured to guide illumination light from a light source capable of emitting the illumination light intermittently and apply the illumination light to an object; an imaging element including a light receiver where multiple pixels configured to receive light and perform photoelectric conversion to generate electric signals are arranged in a two-dimensional matrix, and a reader configured to sequentially read the electric signals per horizontal line from each of the multiple pixels; a generator configured to, based on a first vertical synchronization signal that is input from an external processor and reference timing of exposure of the imaging element with the illumination light, generate a second vertical synchronization signal for controlling timing at which the reader reads the electric signal; and an imaging controller configured to cause the reader to read the electric signals sequentially according to the second vertical synchronization signal.