Firing arrangement

Abstract

A firing arrangement for an initiator (1) includes a capacitor (16), an arming arrangement (6, 11, 14) for charging the capacitor (16) on receipt of an arming instruction and a trigger device (13). When a trigger condition is achieved which indicates sufficient charge on the capacitor (16), a trigger signal is automatically generated by the trigger device (13) to trigger discharge of the capacitor (16) through the initiator (1) to activate the initiator (1). The trigger condition may be a predetermined time after receipt of the arming instruction.

1 . A firing arrangement for an initiator comprising: a capacitor; an arming arrangement for charging the capacitor on receipt of an arming instruction; and a trigger device which, when a trigger condition is achieved indicating sufficient charge on the capacitor, automatically generates a trigger signal to trigger discharge of the capacitor through the initiator to activate the initiator. 
     
     
         2 . The firing arrangement as claimed in  claim 1  wherein the trigger condition is a predetermined time from when charging the capacitor begins. 
     
     
         3 . The firing arrangement as claimed in  claim 2  and including a pulse counter to count a series of pulses to determine when the predetermined time is reached. 
     
     
         4 . The firing arrangement as claimed in  claim 1  wherein the trigger condition is when the voltage across the capacitor reaches a threshold value. 
     
     
         5 . The firing arrangement as claimed in  claim 1  wherein the arming arrangement includes a sequence validator having a first input, a second input and an output, the sequence validator generating the arming instruction at its output only when a first arming signal is received on the first input followed by a second arming signal received on the second input. 
     
     
         6 . The firing arrangement as claimed in  claim 5  and including a first static switch and a second static switch each of which, in an open state, interrupts the firing arrangement such that arming is not possible and, in a closed state, completes part of the firing arrangement, the first static switch and the second static switch being connected to close on receipt of the first and second arming signal respectively. 
     
     
         7 . The firing arrangement as claimed in  claim 2  and including a low voltage capacitor arrangement, a dynamic switch and a transformer, the dynamic switch being operative during arming to discharge the low voltage capacitor arrangement via a transformer to charge the capacitor. 
     
     
         8 . The firing arrangement as claimed in  claim 7  wherein the dynamic switch is operative during arming at a frequency in the range 100 kHz to 1 MHz. 
     
     
         9 . The firing arrangement as claimed in  claim 7  and including a dynamic pulse generator connected to receive the arming instruction and to output a series of pulses to operate the dynamic switch when the arming instruction is received. 
     
     
         10 . The firing arrangement as claimed in  claim 9  wherein the pulse counter is connected to receive the series of pulses from the dynamic pulse generator. 
     
     
         11 . The firing arrangement as claimed in  claim 1  wherein the time period from receiving the arming instruction to generating the trigger signal is 1 ms or less. 
     
     
         12 . A firing system comprising a firing arrangement as claimed  claim 1  and an initiator. 
     
     
         13 . The firing system as claimed in  claim 12  wherein the initiator is one of: an Exploding Foil Initiator (EFI); a Pyrotechnic Igniter; a Bridge Wire (BW); a Film Bridge (FB); a Conducting Composition (CC); a Semiconductor Bridge (SCB); and a Semiconductor Initiator (SCI).