Constant-current, rail-voltage regulated charging electronic detonator

Abstract

Regulated charging of an energy storage module in a pyrotechnic device such as a firing capacitor in an electronic detonator, preferably in the form of constant-current charging limited at a “rail voltage,” and optionally limited to a sufficiently low current to provide additional benefits to the pyrotechnic device such as in the case of a short-circuit.

1 . A pyrotechnic device comprising: 
 a) an igniter;    b) a firing energy storage module connected to said igniter; and,    c) a constant current charging module connected to said firing energy storage module, said constant current charging module being configured and/or programmed to charge said firing energy storage module with a substantially constant current until a predetermined rail voltage corresponding to the desired firing energy of said firing energy storage module is reached, such that the voltage of said firing energy storage module increases substantially linearly with respect to time during said charging.    
     
     
         2 . The pyrotechnic device of  claim 1 , wherein said firing energy storage module is connected to said constant current charging module by a switch and said firing energy storage module is connected to said igniter by a switch.  
     
     
         3 . The pyrotechnic device of  claim 2 , wherein said firing energy storage module is a firing capacitor.  
     
     
         4 . The pyrotechnic device of  claim 3 , further including means for verifying that said firing capacitor has an acceptable capacitance.  
     
     
         5 . The pyrotechnic device of  claim 4 , wherein said pyrotechnic device is an electronic detonator.  
     
     
         6 . The pyrotechnic device of  claim 5 , further comprising an ASIC containing said constant current charging module.  
     
     
         7 . The pyrotechnic device of  claim 6 , wherein said electronic detonator is for use in a system of multiple detonators, and said constant current charging module is configured and/or programmed to limit current to said firing capacitor to below an amount that could cause excessive voltage sagging in said system.  
     
     
         8 . The pyrotechnic device of  claim 7 , wherein said constant current charging module is further configured and/or programmed to limit current to below an amount that could result in inadvertent firing of said igniter.  
     
     
         9 . The pyrotechnic device of  claim 7 , wherein said constant current charging module is further configured and/or programmed to activate in response to an arming command.  
     
     
         10 . A method of charging a pyrotechnic device comprising the following steps: 
 a) providing at least one pyrotechnic device with an igniter and a firing energy storage module; and    b) charging said firing energy storage module in preparation for firing of said pyrotechnic device, wherein current to said firing energy storage module is limited to a constant current, and the voltage of said firing energy storage module increases substantially linearly with respect to time until a predetermined rail voltage corresponding to the desired firing energy of said firing energy storage module is reached.    
     
     
         11 . The method of  claim 10 , further comprising the step of establishing a system including multiple pyrotechnic devices each having an igniter and a firing energy storage module, said system including a master device and a bus connecting said master device to said pyrotechnic devices.  
     
     
         12 . The method of  claim 11 , wherein said system is an electronic blasting system, said master device is a blasting machine, said pyrotechnic devices are electronic detonators, and said firing energy storage modules are firing capacitors.  
     
     
         13 . The method of  claim 12 , further comprising the step of conducting a capacitance check on each of said firing capacitors.  
     
     
         14 . The method of  claim 13 , wherein each of said electronic detonators includes a constant current charging module.  
     
     
         15 . The method of  claim 14 , wherein each of said capacitance checks is conducted at least partly during step b).  
     
     
         16 . The method of  claim 14 , further comprising the step of issuing an arming command from said blasting machine, said constant current charging module configured and/or programmed to activate in response to said arming command.  
     
     
         17 . The method of  claim 16 , wherein said firing capacitor is connected to said constant current charging module by a switch and said firing capacitor is connected to said igniter by a switch.  
     
     
         18 . The method of  claim 17 , wherein said firing capacitors are charged in a staggered fashion.  
     
     
         19 . A constant current charging module for use in an electronic detonator having a firing energy storage module, said constant current module being configured and/or programmed to charge said firing energy storage module with a substantially constant current until a predetermined rail voltage corresponding to the desired firing energy of said firing energy storage module is reached, such that the voltage of said firing energy storage module increases substantially linearly with respect to time during said charging.  
     
     
         20 . The constant current charging module of  claim 19 , wherein said constant current charging module is configured and/or programmed to respond to an arming command issued from a blasting machine and said firing energy storage module is a firing capacitor.