Capsule Endoscope Protection Circuit Prevents Midpoint Potential Latch-Up
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Solution Overview
Problem
Capsule endoscopes experience a latch-up phenomenon and false operations due to midpoint potential issues when batteries are used for extended periods, leading to instability in switching circuits and reduced functionality.
Innovation Solution
A body insertable apparatus with a function executing unit, an electric-power accumulating unit, a detector, and a switching controller that exhausts electric power by switching the power supply from the function executing unit to a separate exhaustion unit based on detection results, preventing midpoint potential-related false operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the battery is used for a long time to extend the observation period, then the duration of action is improved, but the reliability deteriorates due to midpoint potential causing latch-up phenomenon and false operations
Solution Approach 1:
The protection circuit performs preliminary detection of battery voltage before the latch-up phenomenon occurs. When the voltage reaches the predetermined threshold (midpoint potential), the circuit proactively switches off the power supply to the function executing unit, preventing the latch-up phenomenon and false operations from occurring in the first place.
Solution Approach 2:
The protection circuit acts as an intermediary between the battery and the function executing unit. It monitors the battery voltage and controls the power supply switching, serving as a mediator that protects the function executing unit from the harmful effects of midpoint potential while enabling extended battery usage.
2Reliability
If a switching circuit is added to disconnect the battery at midpoint potential, then the reliability is improved, but the device complexity increases
Solution Approach 1:
Instead of making the entire circuit complex, the protection circuit is designed as a localized, dedicated module with specific functions (voltage detection and switching control). This localized approach adds minimal complexity only where needed (in the power supply control path) while keeping the rest of the capsule endoscope system simple.
Solution Approach 2:
The protection circuit implements a simple feedback mechanism where the detected battery voltage is continuously monitored and compared against a predetermined threshold. When the threshold is reached, the circuit automatically triggers the switching action. This feedback-based control achieves reliable protection without requiring complex control logic or multiple switching components.
Data Source
AI summary
A protection circuit 26c detects a voltage at a point A on an electric-power supply path from a battery 29 to an intra-capsule function executing circuit 30. When the voltage at the point A becomes smaller than a predetermined threshold value (a predetermined midpoint potential), the protection circuit 26c performs a switching control of a switch element 26a, connects the battery 29 to a resistive load 26b, stops supplying driving power to the intra-capsule function executing circuit 30 and at the same time enables to supply electric power to the resistive load 26b, and prevents a false operation of a circuit at the midpoint potential by exhausting the electric power stored in the battery 29 by the resistive load 26b.