Infrared detection system for fault isolation and failure prediction

• US 3,350,702 A
• Filed: 01/26/1965
• Issued: 10/31/1967
• Est. Priority Date: 01/26/1965
• Status: Expired due to Term

• Current Assignee: Ruth A. Herman
• Original Assignee: Ruth A. Herman
• Inventors: Herman, Ruth A.
• Application Number:
  US04/428,273
• Time in Patent Office: 1,008 Days
• US Class Current: 340/520
• CPC Class Codes: G01R 31/309 of printed or hybrid circuits or circuit substrates
• CPC Class Codes: G08B 17/12 Actuation by presence of radiation or particles, e.g. of infrared radiation or of ions

Claims

1. A SYSTEM FOR DETERMINING WHEN AN ENERGIZED CIRCUIT ELEMENT IS FAULTY BY SENSING AND DETECTING VARIATIONS IN THE INTENSITY LEVEL OF INFRARED RADIATION EMITTED FROM SAID CIRCUIT ELEMENT AS COMPARED WITH A PRE-ESTABLISHED INTENSITY OF INFRARED RADIATION EMITTED BY A NORMAL CIRCUIT ELEMENT, SAID SYSTEM COMPRISING A BRIDGE CIRCUIT, A FIRST THERMISTOR FORMING ONE OF THE ARMS OF SAID BRIDGE AND ADAPTED TO BE LOCATED IN RADIATION RECEIVING RELATION TO SAID ENERGIZED CIRCUIT ELEMENT WHEREBY SAID FIRST THERMISTOR VARIES IN RESISTANCE WHEN EXPOSED TO INTENSITY CHANGES OF INFRARED RADIATION EMANATING FROM SAID CIRCUIT ELEMENT, A SECOND THERMISTOR FORMING ANOTHER ARM OF SAID BRIDGE, A FIXED RESISTOR FORMING A THIRD ARM OF SAID BRIDGE, A VARIABLE RESISTOR FORMING THE FOURTH ARM OF SAID BRIDGE WHOSE RESISTANCE IS ADJUSTED TO ESTABLISH NULL CONDITIONS IN SAID BRIDGE UNDER THE CONDITION OF INFRARED RADIATION EMANATING FROM SAID NORMAL CIRCUIT ELEMENT, A VOLTAGE SOURCE CONNECTED ACROSS TWO OF THE FOUR COMMON JUNCTIONS OF SAID BRIDGE, A FIRST RELAY CONNECTED TO THE OTHER TWO COMMON JUNCTIONS OF SAID BRIDGE NORMALLY DEENERGIZED AND BECOMING ENERGIZED DURING UNBALANCING OF SAID BRIDGE BY A PREDETERMINED AMOUNT IN EITHER DIRECTION, SAID RELAY INCLUDING FIRST AND SECOND NORMALLY OPEN CONTACTS, SAID FIRST CONTACT BEING CLOSED WHEN CURRENT FLOW IN SAID FIRST RELAY IS IN ONE DIRECTION AND SAID SECOND CONTACT BEING CLOSED WHEN CURRENT FLOWS IN THE OPPOSITE DIRECTION, A SECOND RELAY, A PICKUP CIRCUIT FOR SAID SECOND RELAY INCLUDING SAID FIRST CONTACT OF SAID FIRST RELAY, FIRST INDICATING MEANS CONTROLLED BY A FRONT CONTACT OF SAID SECOND RELAY, A THIRD RELAY, A PICKUP CIRCUIT FOR SAID THIRD RELAY INCLUDING SAID SECOND CONTACT OF SAID FIRST RELAY, AND SECOND INDICATING MEANS CONTROLLED BY A FRONT CONTACT OF SAID THIRD RELAY.