Electronic Endoscope Clock Synchronization to Prevent Frame Dropping
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Solution Overview
Problem
Electronic endoscopic apparatuses face signal degradation and electromagnetic noise issues due to high-frequency signals transmitted between solid-state imaging devices and image processors, leading to phase shifts between imaging and display clocks, resulting in phenomena like 'passing' or 'frame dropping' during image transmission.
Innovation Solution
The apparatus includes an endoscope with a multiplying/dividing unit to generate a scope-side clock and synchronization signal, and an image processor with independent clock generating units to synchronize the imaging and display clocks, using a phase comparing unit to adjust the display clock frequency and ensure phase alignment, thereby preventing frame dropping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of pixels of solid-state imaging devices is increased, then the image quality is improved, but the frequency of clock signal required for image processing becomes higher, causing signal degradation and electromagnetic noise
Solution Approach 1:
The patent divides the clock signal generation into two independent parts: a master clock generating unit in the image processor and a slave clock generating unit in the endoscope. This segmentation allows each unit to operate independently at its optimal frequency while maintaining synchronization through the master-slave relationship, thereby preventing signal degradation and electromagnetic noise associated with high-frequency transmission.
2Productivity
If the frequency of clock signal is increased to match higher pixel count, then image processing capability is improved, but signal degradation on transmission path becomes greater
Solution Approach 1:
The patent introduces a master clock generating unit as an intermediary that produces a base clock signal, which is then distributed to slave clock generating units. This intermediary approach allows the system to achieve high image processing capability through coordinated operation of multiple slave units while the master unit operates at a lower, more stable frequency that minimizes signal degradation and electromagnetic noise during transmission.
3Adaptability or versatility
If independent clock generating units are used in endoscope and image processor, then adaptability to different imaging conditions is improved, but phase shift between imaging and display clocks occurs, causing frame dropping
Solution Approach 1:
The patent implements a feedback mechanism where the slave clock generating unit in the endoscope receives the master clock signal and adjusts its phase and frequency based on the master clock's timing. This feedback ensures that even though both units can operate independently for adaptability, they remain synchronized to prevent frame dropping and maintain reliable image transmission under various imaging conditions.
Data Source
AI summary
A phase comparing unit compares a phase of an imaging-side synchronization signal with a phase of a display-side clock, and controls oscillation of a display-side clock generating unit based on a result of the comparison. A display timing adjusting unit receives a video signal output from an endoscope at a timing based on the imaging-side synchronization signal and adjusts a synchronization timing of the received video signal to a synchronization timing based on a display-side synchronization signal.