Inspection Apparatus Current Control for Spark Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in insulation inspection of circuit boards is the occurrence of spark discharges during high direct current voltage application, which complicates the calculation of correct insulation resistance values and requires efficient methods to detect and minimize spark phenomena in mass-produced boards.
Innovation Solution
An insulation inspection apparatus with a current control unit that supplies a higher first current to quickly establish a predetermined potential difference between wiring patterns and then switches to a lower second current to reduce the influence of the supply current and enhance spark detection, allowing for accurate and efficient insulation inspection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a relatively high direct current voltage is applied between wiring patterns to perform insulation inspection, then the insulation resistance value can be measured, but a spark (discharge phenomenon) occurs between the wiring patterns before the predetermined time elapses, which changes the insulation resistance value and complicates the calculation
Solution Approach 1:
The patent applies periodic action by using alternating current (AC) voltage instead of direct current (DC) voltage for insulation inspection. The AC voltage is applied at a predetermined frequency (e.g., 50 Hz or 60 Hz), which periodically reverses polarity and prevents the accumulation of charge that leads to spark discharge. This periodic reversal ensures that the insulation resistance measurement can be taken during the stable periods when no discharge occurs, thereby maintaining measurement precision while avoiding the reliability issues caused by sparks.
Solution Approach 2:
The patent changes the parameter of voltage type from direct current (DC) to alternating current (AC). This parameter change fundamentally alters the behavior of the electrical field between wiring patterns. By using AC voltage with predetermined frequency and amplitude, the system avoids the progressive charge buildup inherent in DC applications, thereby preventing spark discharge while still enabling accurate insulation resistance measurement through periodic sampling during stable conditions.
2Productivity
If a high direct current voltage is applied to quickly establish potential difference for efficient inspection, then the inspection time is reduced, but the supply current has a significant influence on the measurement and may cause spark discharge
Solution Approach 1:
The patent uses periodic AC voltage application to achieve both efficiency and precision. The predetermined frequency of the AC voltage allows for rapid cyclic establishment and dissipation of potential difference, enabling quick measurements during stable periods. This periodic action maintains inspection efficiency by avoiding the need for prolonged DC voltage application while ensuring measurement accuracy by taking readings during discharge-free cycles.
Solution Approach 2:
The patent incorporates feedback mechanisms to monitor the actual voltage and current conditions during insulation inspection. By continuously monitoring the electrical parameters and detecting any signs of abnormal current draw or voltage deviation that would indicate impending discharge, the system can adjust the applied voltage amplitude or frequency in real-time. This feedback control ensures that the predetermined voltage level is maintained without exceeding safe thresholds that would cause spark discharge, thereby preserving both inspection efficiency and measurement accuracy.
Data Source
AI summary
In an insulation inspection apparatus configured to perform insulation inspection of a wiring pattern, when a voltage for performing the insulation inspection is applied between inspection objects, a current control unit controls a first current to be greater than a second current, the first current being supplied until the potential difference between the first inspection part and the second inspection part reaches the predetermine potential difference, the second current being supplied when the predetermined potential difference is reached.