Timer-controlled clamp for initiation elements

Abstract

This invention relates to protective circuitry ( 12 ) for electrical initiation elements ( 10 ) and finds utility in preventing inadvertent functioning of electrical bridge-initiation elements, such as semiconductor bridges (SCBs), bridgewires, etc., by transient environmental electrical signals. The protective circuitry ( 12 ) of this invention comprises a timer portion ( 14 ) and a clamping portion ( 16 ) and is designed to divert from the electrical initiation element ( 10 ) at least a portion of an electrical signal received at the input nodes ( 10 a , 10 b ) thereof for a suitable time interval that corresponds to the duration of an expected transient signal, which is typically significantly smaller than the duration of a proper initiation signal.

1 . An initiator device comprising: 
 an electrical initiation element having signal input nodes thereto;    protective circuitry connected across the signal input nodes, the protective circuitry comprising a clamping portion responsive to input signals at the input nodes to divert from the initiation element at least a portion of such input signals, the clamping portion being responsive to a release signal to permit the input signal to pass to the initiation element upon receipt of such release signal; and    a timer portion connected to the clamping portion and to the input nodes, and being responsive to such input signals, for issuing a release signal to the clamping portion after passage of a clamping interval after the receipt of the input signal.    
   
   
       2 . The initiator device of  claim 1  wherein the clamping interval is about 100 microseconds or less.  
   
   
       3 . The initiator device of  claim 2  wherein the clamping interval is in the range of from about 5 microseconds to 100 microseconds.  
   
   
       4 . The initiator device of  claim 2  wherein the clamping interval is in the range of from about 20 microseconds to 100 microseconds.  
   
   
       5 . The initiator device of  claim 1  comprising a unipolar clamping circuit and a unipolar timer circuit.  
   
   
       6 . The initiator device of  claim 1  comprising a bipolar clamping circuit and a bipolar timer circuit.  
   
   
       7 . The initiator device of  claim 1  wherein at least one of the electrical initiation element and the protective circuitry are formed as integrated circuitry.  
   
   
       8 . The initiator device of  claim 7  wherein the initiation element and protective circuitry are mounted on a header comprising two electrical leads connected to the protective circuitry, and further comprising a shell mounted on the header and a charge of reactive material in the shell for initiation by the initiation element.