Endoscope LED Timing Control for Rolling-Shutter Image Stability
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Solution Overview
Problem
In electronic endoscope systems using CMOS image sensors, the lighting start time of light emitting devices can be delayed from the light emission start time, leading to deterioration of still images due to synchronization issues, especially when the distance from the endoscope's distal end to the object is short.
Innovation Solution
An electronic endoscope system with a control unit that stabilizes the lighting start time by controlling the current setting signal to rise before the light emission start time, incorporating a preliminary light emission period and adjusting the current level to 10 times the minimum value, and implementing calibration to ensure consistent light amounts across multiple light emitting devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the current setting signal is synchronized with the light emission start time of one frame, then the control timing is simplified, but the lighting start time of the light emitting device is delayed from the light emission start time, causing image deterioration
Solution Approach 1:
The current setting signal is made to rise from zero before the light emission start time of the frame. This preliminary action ensures that the light emitting device is fully activated and stable before imaging begins, eliminating the delay between signal initiation and actual light emission, thereby preventing image deterioration while maintaining control simplicity.
2Use of energy by moving object
If weak pulse light emission is performed when the distance from the distal end portion to the object is short, then energy consumption is reduced, but the lighting start time becomes delayed from the light emission start time
Solution Approach 1:
The current setting signal rises from zero in advance before the light emission start time, ensuring the light emitting device reaches its operational state before imaging begins. This preliminary activation eliminates timing delays while maintaining weak pulse light emission for energy efficiency when the distance to the object is short.
Solution Approach 2:
The timing parameter of the current setting signal is changed to rise before the light emission start time rather than being synchronized with it. This parameter adjustment ensures proper timing alignment between the control signal and light emission, preventing delays while maintaining energy-efficient weak pulse operation.
3Reliability
If the current setting signal rises from zero before the light emission start time, then the lighting start time is stabilized, but the signal timing control becomes more complex
Solution Approach 1:
The current setting signal is designed to rise from zero before the light emission start time as a standard operational procedure. This preliminary action stabilizes the lighting start time by ensuring the light emitting device is fully activated before imaging, and the timing is managed through systematic control of the current setting signal waveform.
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
The solution stabilizes the lighting start time, preventing image deterioration and ensuring consistent illumination, thereby improving image quality in electronic endoscope systems.
Implementation Method 1
a semiconductor light source including a light emitting device such as a light emitting diode (LED) that emits light having a specific wavelength band
Implementation Method 2
a light emitting device that generates illumination light with respect to the biological tissue
Data Source
AI summary
One aspect of the present invention is an electronic endoscope system including an electronic scope including a CMOS image sensor configured to image a biological tissue in a rolling shutter method, a light source device including a light emitting device for generating illumination light for the biological tissue, and a driver signal processing unit. The driver signal processing unit allows the light emitting device to perform a light emission operation on the basis of a signal of a level corresponding to an amplitude of a current allowed to flow through each of the light emitting devices, a current setting signal for setting the current allowed to flow through the light emitting device, and controls the current setting signal in such a manner that a level of the current setting signal rises from zero before a light emission start time of a frame when the CMOS image sensor images.