Ammunition and explosives – Igniting devices and systems – Arming devices
Reexamination Certificate
1999-03-09
2001-10-02
Jordan, Charles T. (Department: 3641)
Ammunition and explosives
Igniting devices and systems
Arming devices
C102S221000, C102S264000
Reexamination Certificate
active
06295931
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention (Technical Field)
The present invention relates to ordnance fuzes, particularly to safety and rangefinding apparatus for fuzes, and specifically to a magnetic field sensor for ordnance fuzes.
2. Background Art
Modem military ordinance is becoming increasingly sophisticated in an attempt to upgrade safety handling and targeting accuracy. Improved environmental sensors are needed to address these issues. Safing procedures require at least two independent indicators that the round is safe to be armed. Typically, one of these indicators must be environmental (e.g., an accelerometer) and the second can be a timer. A second, positive indicator of safe separation would materially enhance safing mechanisms. Effective ordinance range is more determined by accuracy than absolute distance to target. If sensors on a round were able to use environmental information to keep track of a round's location, effective ordinance range could be expanded.
Fuze technology was based on mechanical devices for many years, typically with each ordinance type and each branch of military having unique implementations. The advent of the exploding foil initiator (EFI) has been instrumental in allowing the transition of some fuzes from mechanical to electronic format. Recent changes are integrating more sophisticated processing into the electronic fuze as a means to improve handling and launching safety as well as targeting accuracy. The Multi-Option Fuze for Artillery (of MOFA) is an example of the current goals for military-wide standardization. Intelligent, in-barrel programmable fuzes being developed today allow a single fuze to fulfill many types of missions.
SUMMARY OF THE INVENTION (DISCLOSURE OF THE INVENTION)
The present invention is of an apparatus and method for electronically controlling ordnance fuzes, comprising sensing magnetic fields proximate the ordnance via a magnetic field sensor. In the preferred embodiment, sensing is done via a giant magnetoresistance detector. For spinning ordnance, in-flight cumulative range can be calculated, preferably by counting turns of the spinning ordnance. Ordnance may be armed a pre-determined time after exit of the ordnance from a weapon firing the ordnance, which can be done with the magnetic field sensor determining the time of exit of the ordnance from the weapon firing the ordnance.
The present invention is also of a giant magnetoresistance sensor and method for making same comprising: providing a magnetic substrate pinned with NiMn; forming a tunnel barrier on said substrate; and forming a topmost permalloy layer. In the preferred embodiment, the tunnel barrier is formed with thermally oxidized Al, preferably according to the National Institute of Standards Josephson junction process.
The present invention is additionally of an apparatus for and method of sensing angular velocity for spinning ordnance comprising: counting turns of the ordnance via a magnetic field sensor; and computing a time derivative of an inverse sine of an output of the counting step.
A primary object of the present invention is to provide for intelligent control of ordnance fuzes using ultra-sensitive magnetic field sensors.
A primary advantage of the present invention is that it provides for such control in both spinning and non-spinning rounds.
Other objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
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Boltz Eric S.
Cutler David W.
Jarratt, Jr. Raymond L.
Jordan Charles T.
Myers Jeffrey D.
Semunegus Lolit
TPL, Inc.
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