Image Signal Sampling Clock With Phase Delay Compensation
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Solution Overview
Problem
Video imaging systems in endoscopes face distortion issues due to signal transmission line mechanics and propagation delay, leading to inaccuracies and noise in the displayed image, particularly exacerbated by the use of analog delay lines which introduce jitter and instability.
Innovation Solution
A high precision, low noise master clock system is implemented adjacent to the Analog Front End (AFE)/Analog-to-Digital Converter (ADC) with programmable high-speed clocks, using a phase detection circuit to adjust the timing generator and avoid direct use of delayed signals, thereby reducing jitter and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cable length is increased to accommodate various endoscope applications, then versatility is improved, but signal transmission quality deteriorates due to propagation delay and distortion
Solution Approach 1:
The system dynamically adjusts the phase of timing signals based on detected cable length. The phase detector measures the actual phase relationship between transmitted and received timing signals, and the system modifies the timing signal phase parameter to compensate for propagation delay, maintaining signal quality across different cable lengths
Solution Approach 2:
A feedback mechanism is implemented where the phase detector continuously monitors the phase relationship between transmitted and received timing signals. This feedback information is used to automatically adjust the timing signal phase, creating a closed-loop system that maintains optimal signal quality regardless of cable length variations
2Measurement precision
If analog delay lines are used to compensate for timing signal delay, then timing accuracy is improved, but system stability deteriorates due to jitter introduction
Solution Approach 1:
The system replaces analog delay lines with a digital/phased-locked approach using a phase detector and programmable timing signal generation. Instead of using physical analog delay elements that introduce jitter, the system uses digital phase measurement and adjustment to achieve timing accuracy without the instability associated with analog delay mechanisms
3Reliability
If a dedicated CCU is provided for each endoscope, then signal processing quality is improved, but system complexity and cost increase
Solution Approach 1:
The system implements a universal CCU design that can handle multiple endoscope types through automatic cable length detection and adaptive timing signal adjustment. The single CCU incorporates a phase detector and programmable timing generation that automatically adapts to different cable lengths and endoscope configurations, eliminating the need for dedicated CCUs for each endoscope while maintaining signal processing quality
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 significantly reduces image noise by improving control over sample timing, eliminating the need for analog delay lines and minimizing jitter, resulting in a more stable and accurate video signal transmission.
Implementation Method 1
a phase detection circuit coupled to the analog front end circuit and receiving the first timing signal transmitted from the imager, and the second timing signal, wherein the phase detection circuit makes a plurality of comparisons between a signal state of the first timing signal received from the imager to a signal state of the second timing signal
Data Source
AI summary
A system is provided that measures the delay time of a first timing signal transmitted from a control unit to an imager and back to a phase detector. The phase detector also receives a second timing signal that is used as a reference to measure against the received/delayed first timing signal. Based on the phase detection, the system will retard or advance the first timing signal to compensate for the phase shift.