Patent Publication Number: US-2005115442-A1

Title: Pyrotechnic device for destruction of valuable documents

Description:
FIELD OF THE INVENTION  
      This invention relates a device for destruction of valuable documents and more particularly to a pyrotechnic device for destruction of valuable documents which is capable to destroy efficiently the documents contained therein, independently of the amount and/or thickness.  
     BACKGROUND AND PRIOR ART  
      Prior pyrotechnic based techniques for the rapid and reliable destruction of valuable documents are severely limited in the thickness of the document stack which they can reliably destroy. Protection systems based on prior art which are intended to destroy large quantities of notes therefore require multiple pyrotechnic charges and their associated multiplicity of ignition systems and circuits. They also require that large stacks of documents be split into many smaller stacks in order not- to exceed the maximum thickness constraint.  
      Documents to be potentially destroyed are more conveniently arranged in large piles or stacks however, whether for storage, transport, or in particular in automated handling and teller systems. 
    
    
     DESCRIPTION OF THE INVENTION  
      A device for the rapid and controlled destruction of a large number of valuable documents is described. The device comprises a primary incineration charge, a propellant charge and an extinguisher charge. The two former are electrically triggered by an external signal, and the latter is triggered once a precise portion of the propellant charge has been consumed. In addition to the charges, the device includes electrically triggered igniters and initiators, a fully-sealed long lifetime battery, fully-sealed trigger reed switches, and associated circuits and wiring.  
      The primary destruction mechanism is by high-temperature incineration, caused by well known, localized, Metal/Metal-Oxide exothermic redox reaction. The invention utilizes a single composite pyrotechnic charge and housing to destroy a specific portion of every document in a stack. Since the design is linearly scalable to arbitrary limits, only one charge is required for any number of stacked documents. This is in contrast to existing thermite torch based systems, which are limited in the maximum thickness of the stack that can be satisfactorily and reliably destroyed. The present invention thus has a wider field of application, as well as offering considerable cost savings, in comparison to existing methodologies.  
      The main incineration charge is housed within a rectangular section metal tube (A). The side of the tube which will face toward the document stack has an opening (B) along that part of its length corresponding to the maximum length of the document stack to be destroyed. This opening is covered with a thinner metal or plastic burst sheet (C), which seals and protects the charge before deployment. The incineration charge is contained within the rectangular tube, and comprises separate igniter/initiator/propagation layers (D) laminated with the primary high-temperature redox components (E). The primary charge tube is fixed inside a metal/refractory material housing (F), and retained in position with heat-sensitive release beads (G). A solid propellant charge is enclosed within the volume formed between the housing and the charge, and held in place either by a spring clip, by conventional adhesive, or by the technique of casting in place. One end of the propellant charge is equipped with a conventional electric-match type igniter device (not shown, for clarity).  
      In operation, the primary incineration charge and the propellant are simultaneously ignited when the trigger signal energizes reed relay solenoids, causing them to dose.  
      Battery power is then supplied to both the propellant igniter and the main charge igniters/propagators.  
      The increase in temperature from both the primary charge and the propellant exhaust gases cause the thermal release beads to activate, allowing the main primary charge to move into contact with the documents. The increasing pressure from the propellant forces the primary charge unto the document, and the high temperatures generated by the charge destroy them. A conventional relay fuse placed near the end (i.e. the last portion to be consumed) of the propellant charge then triggers a Nitrogen generating charge to suppress fire propagation within and from the destroyed documents.  
      Naturally, the invention is not limited to the embodiment describe above, other alternative forms whereof can be provided without departing thereby from the scope of the attached claims.