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Smokeless Fire Detection for Electronic Systems Disclosure Number: IPCOM000010135D
Original Publication Date: 2002-Oct-24
Included in the Prior Art Database: 2002-Oct-24
Document File: 7 page(s) / 167K

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Page 1 of 7

Smokeless Fire Detection for Electronic Systems

   Disclosed is a method which allows for the detection of printed circuit board damage due to an electronic short circuit or other cause within an electronic complex without the use of smoke detectors. Using additional wires and/or wiring levels around key areas within an electronic complex, a damaged printed circuit board can be detected with the proper stimulus and detect circuitry as indicated below. The function of the additional wiring is similar to that of a fuse, but unique in that this wiring is not supplying power to any part of the complex. Rather it is simply being used as a distributed sensor that can detect a short or open due to printed circuit board damage.

The main concept is to create within the system a network of wire, proportionately small to the printed circuit board and/or system wiring, but highly distributed such that any damage due to a short circuit where smoke or flame would normally occur would be detected causing the system to shut down before more damage takes place. This is accomplished by wiring around traditional areas where shorts often occur with a wire that is sensed for any short or open continuously. Any short or open detected feeds back information through any one of several means to the power supply (or power supplies) so that they can be shut down as soon as damage begins to occur. The intent is to prevent smoke and/or flame damage from even happening. Although a system shutdown would occur, the ultimate cause of the failure would in all likelihood be preserved. Damage to the printed circuit board for other reasons (such as mechanical damage, chemical damage, etc.) would also be detected with this method.

More specifically, the protected card or assembly needs to have a wire that essentially is routed around various aspects of the printed circuit board, card, or assembly. Typical areas where such a wire would be routed include the card perimeter, near the connector, near power via's (or other via's as well), and near components to the extent wiring channels are available. The general concept would be to protect whatever you can with any available wiring channel and in fact multiple wiring levels could be used on a printed circuit board to accomplish this. In the most comprehensive form, a dedicated wiring level could be used which would contain a serpentine wire that virtually covered the entire card area except for where via's existed. The following figures will help demonstrate the general idea of this concept.

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Fig. 1 - Simple, On Card Fire Wire Detect



Fig. 2 - On Card Power Via Fire Wire Detect


Figure 1 shows a printed circuit board card with a wire going around the card, and Figure 2 similarly but with the wire also going around some of the via's along with a block diagram representing both sending and detection logic imbedded in an on card logic component or stand alone component for the purpose of detec...