The present invention relates generally to a system and method for producing and directing sound loud enough to be used as a weapon. More particularly, the present invention relates to a method of using partially confined gas detonation to produce and direct very loud sound waves toward people, structures or animals for use as a weapon.
In the process of conducting warfare in urban settings it is often desired to employ a weapon that causes limited or no damage to people and/or structures. The arsenal available to a typical fighting force however was designed for all out war and as a consequence was designed to produce the maximum lethality and property damage. Ironically it is the extreme lethality of such weapons that puts the US and Coalition warfighters in the greatest danger in an urban setting. While putting an M1A1 round into an apartment building would definitely quiet a sniper, normal hesitation to create high levels of collateral civilian damage and injury increases the chances of friendly casualties and permits possible escape of the perpetuator.
Urban warfare as encountered in both Iraq and Afghanistan is new to the military and must be fought using a new set of rules and new technology that can meet and overcome both today's and tomorrow's asymmetric threats. What is sorely needed is the capability of returning an overwhelming counter force that gives the warfighter the option of not causing permanent injury or severe property damage in urban settings.
US warfighters, to include such agencies as for example SWAT teams, engaged in combat today require lightweight, modular, versatile, and effective multiple-use systems to meet and overcome the growing and evolving challenges and threat posed by asymmetric warfare. New engagement Doctrine and operational practices which are not cumbersome to the soldier need to be employed. A multiple-use system concept is needed that enables the warfighter to apply an overwhelming, ordnance-free force that can most often avoid the consequences of unwanted collateral damage and casualties.
Today's mines are much more lethal and are designed to overcome conventional mine neutralization methods and techniques. Many modern mines contain a “dash pot” on the trigger that requires application of force for a period of time longer than that of an aerial explosion. This change was made to prevent using aerial bursts and line charges to easily clear a mine field. New methods are needed that can apply a force over such a period of time as to overcome this countermeasure thereby allowing a lane to be cleared by detonating mines a safe distance in front of a convoy.
Equally as insidious as mines are Improvised Explosive Devices (IEDs). The well camouflaged, consistently evolving, and highly lethal IEDs used by terrorists and insurgents alike have accounted for the majority civilian and US/Coalition warfighter casualties in the Middle Eastern Theatre of Operations. New technologies and doctrine to counter evolving threats must be rapidly brought to bear and used as a disrupter against these types of threats.
New technologies are also needed for military perimeter defense purposes and for homeland defense of borders, protection of assets such as dams, airports, power facilities, water treatment plants, etc.
Moreover new technologies are needed to combat underwater threats.
The present invention is an improved system and method for generating, projecting and steering very loud sound pulses to remote targets such as people, animals and structures. These sound levels that can be projected may vary from annoying at the low end, disabling at the mid range and lethal at the high end. They may also be employed against structures to for example break windows, knock down doors or set up resonances within structures to alarm the occupants, to weaken them or to collapse them.
It is possible using this invention to construct weapons of either a fixed level of energy or one that can be adjusted over a range of output levels depending on the immediate needs. It is also possible to use the present invention to generate and direct conducted acoustic purposes into the water, which can be used for underwater imaging and also for defensive purposes.
The present invention provides a system for producing a sound wave having at least one detonation tube apparatus and at least one timing control mechanism. The detonation tube apparatus, at least one detonator, and a fuel mixture supply system. Each detonation tube has a closed end and an open end. Each detonator has at least one spark initiator. The fuel mixture supply subsystem supplies a fuel-oxidant mixture to the at least one detonator that flows through the at least one detonator and into the closed end of the at least one detonation tube and can optionally also supply a fuel-oxidant mixture directly to the at least one detonation tube. The timing control mechanism controls the timing of the at least one spark initiator initiating at least one spark within the at least one detonator while said fuel-oxidant mixture is flowing through the at least one detonator thereby initiating a detonation wave at the closed end of the at least one detonation tube. The detonation wave then propagates the length of the at least one detonation tube and exits the open end of the at least one detonation tube as a sound wave that can be used to incapacitate a person, detonate a mine, or detonate an improvised explosives device.
The fuel-oxidant mixture can have a desired mass ratio of fuel versus oxidant and a desired flow rate selected based on the length and diameter of the at least one detonation tube and the at least one detonator. The spark initiator can be a high voltage pulse source, a triggered spark gap source, a laser, or an exploding wire. The timing control mechanism can be a trigger mechanism, fixed logic, or a control processor. A control processor can be used to control variable parameters of the fuel mixture supply subsystem.
The fuel-oxidant mixture can be gaseous or dispersed and can be methane, propane, hydrogen, butane, alcohol, acetylene, MAPP gas, gasoline, or aviation fuel.
The timing control mechanism can cause a plurality of detonation tubes to produce a plurality of the detonation waves that are timed to direct sound waves to a desired location in order to incapacitate a person, detonate a mine, or detonate an improvised explosives device.
The timing control mechanism can cause a plurality of detonation tube arranged in a sparse array to produce a plurality of the detonation waves that are timed to direct sound waves to a desired location in order to incapacitate a person, detonate a mine, or detonate an improvised explosives device.
The invention can include at least one coupling component corresponding to each at least one detonation tube apparatus that couples the recoil force of the sound wave to water to produce a conducted acoustic wave. A plurality of detonation tube apparatuses arranged in a sparse array, each having a coupling component, can produce a plurality of conducted acoustic waves with controlled timing in order to direct them to a desired location in the water.
The invention can include at least one weapons platform that could be any one of a tripod, a robot, an unmanned ground vehicle, an unmanned aerial vehicle, a HMMV, an armored personnel carrier, a boat, a ship, a helicopter, a tank, an artillery platform, an airplanes, a soldier.
The at least one detonation tube could include a graduating detonation tube combination, a detonation tube group, a compression technique, or an expander technique.
The invention provides a method for producing a sound wave including the steps of supplying a fuel-oxidant mixture to at least one detonator having at least one spark initiator where the fuel-oxidant mixture flows through the at least one detonator and into the closed end of at least one detonation tube also having an open end, and controlling the timing of the at least one spark initiator to initiate at least one spark within the at least one detonator while the fuel-oxidant mixture is flowing through the at least one detonator thereby initiating a detonation wave at the closed end of the at least one detonation tube where the detonation wave propagates the length of the at least one detonation tube and exits the open end of the at least one detonation tube as a sound wave.
The at least one detonation tube could be a plurality of detonation tubes where the controlling of the timing of the at least one spark initiator causes a plurality of sound waves to be directed to a desired location.
The present invention is described with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. Additionally, the left-most digit(s) of a reference number identifies the drawing in which the reference number first appears.
The present invention will now be described more fully in detail with reference to the accompanying drawings, in which the exemplary embodiments of the invention are shown. This invention should not, however, be construed as limited to the embodiments set forth herein; rather, they are provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.
The present invention provides an improved system and method for generating and controlling an overpressure wave, which is also be referred to herein as a sound wave or sound pulse. Exemplary overpressure waves can be characterized by their frequency in the range of 0.1 Hz to 30 KHz. The basis of the system is the ignition of a high energy, detonable gaseous or dispersed fuel-air or fuel-oxygen mixture within a tube that is open at one end, where any of a number of flammable fuels can be used including ethane, methane, propane, hydrogen, butane, alcohol, acetylene, MAPP gas, gasoline, and aviation fuel. The gas mixture is detonated at the closed end of the tube causing a detonation wave to propagate the length of the tube where detonation ends and the detonation wave exits the open end of the tube as an overpressure wave. The tube is referred to herein as a detonation tube and the detonation wave is referred to herein as a detonation pulse or impulse.
One embodiment of the present invention comprises at least one detonation tube apparatus and a timing control mechanism for controlling the timing of detonations. The detonation tube apparatus comprises at least one detonation tube, at least one detonator, and a fuel-oxidant mixture supply subsystem. One or more detonators can be used with a given detonation tube and a detonator can be used with multiple detonation tubes. Associated with the one or more detonators is one or more spark initiators where a single spark initiator may initiate sparks in multiple detonators, which may be in parallel or in series, and multiple spark initiators may initiate sparks in a single detonator. The timing control mechanism controls the timing of the one or more spark initiators.
The spark initiator may be a high voltage pulse source. As an alternative to the high voltage pulse source a triggered spark gap approach can be used a spark initiator. Other alternatives for a spark initiator include a laser and an exploding wire.
The timing control mechanism can be a simple trigger mechanism, fixed logic, or be a more complex control processor. A control processor may also be used to control variable parameters of the fuel-oxidant mixture supply subsystem or such parameters may be fixed.
The fuel-oxidant mixture supply subsystem maintains a desired mass ratio of fuel versus oxidant of the fuel-oxidant mixture and a desired flow rate of the fuel-oxidant mixture. Desired fuel versus oxidant ratio and flow rate can be selected to achieve desired detonation characteristics that depend on length and diameter characteristics of the detonator. For example, one embodiment uses a propane-air fuel-oxidant mixture, a mass ratio of 5.5 and a flow rate of 50 liters/minute for a detonator having a length of 1″ and a ¼″ diameter and made of Teflon, a first detonation tube made of stainless steel having a length of 9″ and a diameter that tapers from 0.8″ at the end connected to the detonator to 0.65″ at the end connected to a second detonation tube made of titanium having a length of 32″ and a 3″ diameter. Alternatively, the first detonation tube may have a constant diameter of 0.8″.
Commercially available mass flow control valve technology can be used to control the mass ratio of fuel versus oxidant of the fuel-oxidant mixture and the flow rate of the fuel-oxidant mixture. Alternatively, commercially available technology can be used to measure the mass flow of oxidant into a fuel-oxidant mixture mixing apparatus and the precise oxidant mass flow measurement can be used to control a mass flow valve to regulate the mass flow of the fuel needed to achieve a desired mass ratio of fuel versus oxidant of the fuel-oxidant mixture.
Detonation within Flowing Fuel-Oxidant Mixture
Prior art gas detonation systems either required long tubes or highly detonable gas mixtures such as oxygen and hydrogen in order to produce a detonation. Otherwise they will only “deflagrate” which is a slow and nearly silent process. In contrast, one aspect of the present invention provides the ability to produce short, high intensity sound pulses within a tube as short as one foot long and 2 inches diameter, using only moderately explosive gas mixtures such as propane and air. Unlike the prior art systems, this aspect of the present invention is embodied in an exemplary system that passes an electric arc through a flowing (or moving) stream of gas and oxidizer mixture that is filling the tube within which the detonation will take place. When the tube is substantially full, a fast spark is initiated within the flowing gas at the filling point in the tube, which triggers the subsequent detonation of all the gas inside the tube. Alternatively, the flowing gas can be detonated by a laser or by any other suitable ignition and detonation method according to the present invention. This ignition within flowing gas technique dramatically shortens the tube length required to produce a detonation when compared to prior art systems that ignited non-flowing or otherwise still gas mixtures. Moreover, detonation according to this aspect of the present invention requires on the order of 1 Joule of energy to detonate the fuel-oxidant mixture whereas prior art systems may require 100's to 1000's of Joules of energy to achieve detonation. Further desirable results of this method are the reduction of uncertainty of time between the electric arc trigger and the subsequent emission of the sound pulse from the tube and the repeatability of detonation pulse magnitude. As such, the detonator according to this aspect of the present invention enables precise timing and magnitude control of an overpressure wave.
Also shown in
For certain fuels it may be necessary to heat the fuel-oxidant mixture in order to achieve detonation. Depending on the rate at which the detonation tube is fired, it may be necessary to cool the detonation tube. Under one preferred embodiment of the invention, fuel supply 105 (and/or 105′) comprises at least one heat exchange apparatus (not shown) in contact with the detonation tube that serves to transfer heat from the detonation tube to the fuel-oxidant mixture. A heat exchange apparatus can take any of various well known forms such as small tubing that spirals around the detonation tube from one end to the other where the tightness of the spiral may be constant or may vary over the length of the detonation tube. Another exemplary heat exchanger approach is for the detonation tube to be encompassed by a containment vessel such that fuel-oxidant mixture within the containment vessel that is in contact with the detonation tube absorbs heat from the detonation tube. Alternatively, a heat exchanger apparatus may be used that is independent of fuel supply 105 in which case some substance other than the fuel-oxidant mixture, for example a liquid such as water or silicon, can be used to absorb heat from the detonation tube. Alternatively, another source of heat may be used to heat the fuel-oxidant mixture. Generally, various well known techniques can be used to cool the detonation tube and/or to heat the fuel-oxidant mixture including methods that transfer heat from the detonation tube to the fuel-oxidant mixture.
Overpressure Wave Magnitude Control
Generally, the length and inside diameter of a detonation tube can be selected to achieve a desired maximum generated overpressure wave magnitude at a maximum selected flow rate of a selected flowing fuel-oxidant mixture, and the flow rate can be reduced to lower the magnitude of the generated overpressure wave. If required, increasingly larger tubes can be used to amplify the detonation pulse initially produced in a smaller detonation tube. Each one or a plurality of the tubes can be made of one or a combination of materials and allows, including PVC or a variety of different compounds, metals, or even concrete to achieve a desired result. In one exemplary embodiment the detonation tube is made of titanium. In an exemplary embodiment, the detonator within which the spark is introduced has a small diameter, e.g. approximately ¼″ diameter. This assembly is aligned to the base of a second larger detonation tube so that the gas contained within it is detonated. This second detonation tube may then be aligned to the base of a successively larger diameter tube to initiate detonation of the gas mixture within. In this way, very large diameter detonation tube detonations may be initiated with precise timing accuracy.
The use of tubes having increasingly larger diameters is shown in
In the exemplary embodiment described above, the detonation tube (and the detonator tube) was assumed to be a tube having a circumference that does not vary over the length of the tube. As an alternative, a detonation tube (or detonator tube) may begin with a small diameter and gradually grow larger in order to have a similar effect of amplifying the pulse as described for
Detonation Tube Arrays
Detonation tubes can be grouped into arrays in various ways to produce a combined pulse when triggered simultaneously.
Alternatively, the detonation tubes that make up such detonation tube groups or arrays can also be triggered at different times. Under one arrangement, detonation tubes are ignited using a timing sequence that causes them to detonate in succession such that a given detonation tube is being filled with its fuel-oxidant mixture while other detonation tubes are in various states of generating an overpressure wave. With this approach, the igniting and filling of the detonation tubes could be timed such that overpressure waves are being generated by the apparatus at such a high rate that it would appear to be continuous detonation.
As shown in
Generally, any of various possible combinations of graduated tubes, tubes of gradually increasing circumferences, tube arrays, groups of smaller tubes connected to larger tubes, and tubes employing the compressor/expander technique can be used in accordance with this aspect of the invention to generate overpressure waves that meet specific application requirements. All such combinations require balancing the energy potential created due to an expansion of a pipe circumference with the cooling caused by expansion of the gases as the tube circumference increases.
Coherent Focusing and Steering of Overpressure Waves
As described previously, the detonator of this aspect of the present invention has low uncertainty of time between the electric arc trigger and the subsequent emission of the sound pulse from the tube. The detonator also provides for repeatable precision control of the magnitude of the generated sound pulses. This low uncertainty, or jitter, and precision magnitude control enables the coherent focusing and steering of the overpressure waves generated by an array of detonation tubes. As such, the detonator can be used to generate steerable, focusable, high peak pulse power overpressure waves.
Individual detonation tubes or groups of tubes can be arranged in a sparse array.
Referring to
The timing control mechanism 216 used in sparse array embodiments may comprise a single timing control mechanism in communication with each of the overpressure wave generators making up the array via a wired or wireless network. Alternatively, each of the overpressure wave generators may have its own timing control mechanism whereby the timing control mechanisms have been synchronized by some means.
Theory of Operation of Detonation Tube Arrays
Generally, when an array of detonation tubes is triggered with precise timing a pressure wave is created that propagates as a narrow beam in a direction mandated by the timing. In this way its operation is analogous to a phased array antenna commonly used in radar systems. Since the timing is determined electrically the beam direction can be redirected from one pulse to the next. Systems can be designed that operate at different rates, for example 10, 20, 50 or 100 pulses per second, and each pulse can be aimed in a unique direction. The only limitation to repetition rate is the speed with which the tubes can be refilled. At a sonic refill rate it would take about five milliseconds to refill a tube five feet long. Since it also takes a pulse five milliseconds to exit once detonated, the limiting repetition rate is 100 Hz.
Since each element of the array emits its own coherent energy, in the far field the amplitude of the wave approaches the square of the intensity of each individual tube. The instantaneous over pressures that can be directed in this way therefore may approach high levels. As such, the system possesses a large overhead dynamic range that can be used to reach a long range or propagate through small apertures in structures such as hard targets.
The structure behind the small aperture can be resonated by application of the pulses at just the right time intervals, as determined by a probe laser used to measure the Doppler shift of particles at the opening. The natural frequency of the structure can thereby be determined and thereafter the laser is used in closed loop mode to control the timing of the system to produce maximum effect. The instantaneous pressures inside such a hard target can be quite large since the acoustic Q is high. For example, for a Q of only 10 the peak pressure could approach 1000 psi.
Groups of detonation tubes can be treated as sub-arrays within a larger array.
Timing of the firing of the array elements of this embodiment is straightforward. The waveform is about one millisecond long and the constraint for coherence is ¼ of its wavelength or less. The timing subsystem therefore will need a resolution and accuracy of 200 microseconds or less. This level of timing accuracy can be accomplished with programmable counter-timers such as Intel's 8254 PCA that provides three channels of timing per chip, at a resolution of 0.1 microsecond.
In one embodiment, each element in a steerable array needs to have its energy spread over the entire area of steerability, for example, with an aperture that has under ½ wavelength. For a one millisecond waveform the aperture is about six inches. In the exemplary embodiment shown in
The focal spot of the array is a function of the wavelength and the size of the array. Near the array face the focal spot comprises an approximate circle one wavelength, i.e. one foot in diameter. At greater distances the spot will gradually spread out in an oval shape with its large diameter in the direction of the small diameter of the array. That is, the oval becomes vertical for the horizontal array depicted in
Measurements of the pressure output of the array can be made with a wide band acoustic sensor. They typically have a bandwidth of 10-20,000 Hz and an accuracy of 1 dB or so. Measurements made at a distance of thirty feet or more in the far field of the array give accuracies sufficient to extrapolate characteristics at any range. The calibrated output of such an instrument is acoustic sound pressure level which has a direct relationship to pressure, i.e.
For example, 180 dBSPL is equivalent to a pressure of 20,000 Pa or about 3 psi. The instantaneous sound intensity associated with this level is 1,000,000 W/m2.
A consequence of the general wave equation for linear media is that when waves superimpose their amplitudes add. For electromagnetic waves this means that if two identical waves arrive at a point in space at the same time and phase they will produce double the potential, or voltage of a single wave.
The result is similar in the case of acoustic waves but in this case the potential is pressure rather than voltage.
p=√{square root over (p12+p22+2p1p2 cos(θ1−θ2))}N/m2
Note that since the phases are equal the cosine is equal to 1 and the value of the pressure is equal to twice the pressure of a single source. This relation applies for the addition of N sources=N*p.
Doubling the pressure of an acoustic waveform quadruples its power since power is proportional to the square of its pressure, namely, when two identical acoustic waveforms arrive at the same point in space at the same time and phase their power will quadruple.
In analogy to electromagnetic waves the power, or acoustic intensity, of a waveform is proportional to the square of its pressure.
Where the denominator is the value of the acoustic impedance of the medium, in this case air.
Therefore, generally the free-space, far-field power in the main lobe of the overpressure waveform can be calculated as N2 of the pressure of a single detonation tube. However, when it is operated near the ground, advantage can also be taken of the additive effect of the ground wave. When the wave from the ground and the free-space waveforms converge on a target the pressures of both waveforms again add and quadruple the power again.
Beam steering is accomplished by adjusting the timing of the individual elements such that the closer ones are delayed just enough for the waves from the further part of the array to catch up. In a given steering direction therefore all of the waves will arrive at the same time and satisfy the N2 power criterion. This is analogous to a phased array antenna but since the acoustic waveform is transient rather than continuous wave, time delay is substituted for phase.
Applications of the Overpressure Wave Generator of the Present Invention
The overpressure wave generator of the present invention, when operated at appropriate levels, for example 10 psi, can be used as a directed sound wave weapon system having the capability to render the recipients unconscious and permit their arrest and detainment. While innocent civilians who may be in the direction of the sound wave will likely be affected similarly, the effects are temporary and will not cause long-term injury. This permits the system to be used with a hair trigger and may even be operated under full automatic control while in particularly hostile environments without the usual concerns accompanying highly lethal systems. The system's non-lethal mode also allows it to be safely used for crowd control.
The directed sound wave weapon system is highly scalable and at more elevated overpressures can be used to achieve standoff distances and/or lethality. The system can be adapted to portable, individual use for deployment inside buildings and caves. In such environments the overpressure wave will propagate efficiently along hallways and cave tunnels that would serve as a wave guide increasing the system's effective range.
When an array of overpressure wave generators is used, the beam steering ability of the sound wave weapon system makes it very effective as an anti-sniper weapon since the sound waves can be directed accurately into windows hundreds of meters away. Since the beam can be electronically directed nearly instantaneously over a wide angle the weapon system can be set to automatically sweep the area around a convoy moving through hostile territory. In particular, the beam can be used to neutralize (i.e., destroy or disable) Improvised Explosive Devices (IEDs) and mines in the path of the convoy.
Using the Recoil Force of an Overpressure Wave for a Water-Based Weapon
The overpressure wave generator of the present invention described above can be augmented so as to harness its recoil force for use as a water-based weapon. In one embodiment of the water-based weapon system in accordance with the present invention, as shown in
The overpressure wave generator 11 of system 2100 comprises what is depicted in
The overpressure wave generator is detonated to generate an overpressure wave, which is optionally muffled by muffler 2124. The generation of the overpressure wave causes a corresponding recoil force which coupling component 2112 couples to water to produce a conducted acoustic wave. Stabilizing mechanism 2113 provides stability to the movement of the overpressure wave generator 11 essentially allowing movement parallel to the tube. The coupling component 2112 may comprise rubber or some comparable compound having desired spring-like and damping characteristics and comprises a diaphragm 2126 that is in contact with the water.
The controller 2114 is used to control the operation of the overpressure wave generator 11. The controller 2114 can be a portable computer or workstation which is programmed to timing when the overpressure wave generator 11 is triggered.
Multiple systems 2100 can be arranged in a sparse array and timing control methods used to steer their conducted acoustic waves such that they combine at a desired location within the water. Such steering is essentially done in the same manner similar as overpressure waves are steered, as described in relation to
The system 2200 can be used to protect ships whereby the systems are installed into the hull of the ships or deployed alongside or near the ships. Similarly, such systems can be used to protect nuclear power facilities, off shore oil platforms, etc. from underwater terrorist attacks. Large scale systems can be used for harbor protection.
The weapon systems described herein can be used with a variety of well known sensor systems and targeting systems. Weapon system embodiments involving a sparse array of weapons will comprise a wired or wireless network and a control processor that controls the timing of detonations of the weapons so as to steer the overpressure waves or conducted acoustic waves to a target coordinate.
The weapon systems described herein were provided as examples of the types of weapons that are enabled by the present invention. While particular embodiments and several exemplary applications (or implementations) of the invention have been described, it will be understood, however, that the invention is not limited thereto, since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. It is, therefore, contemplated by the appended claims to cover any such modifications that incorporate those features or those improvements which embody the spirit and scope of the present invention.
This application claims priority to U.S. Provisional Patent Application 60/792,420, filed Apr. 17, 2006, and U.S. Provisional Patent Application 60/850,683, filed Oct. 10, 2006, both of which are incorporated herein by reference.
Number | Name | Date | Kind |
---|---|---|---|
2994397 | Huckabay et al. | Aug 1961 | A |
3064753 | McClure | Nov 1962 | A |
3233694 | Roever | Feb 1966 | A |
3235026 | Hottman | Feb 1966 | A |
3410142 | Diaber et al. | Nov 1968 | A |
3828886 | Holloway | Aug 1974 | A |
4043420 | Zens et al. | Aug 1977 | A |
4356753 | Galley | Nov 1982 | A |
4642611 | Koerner | Feb 1987 | A |
4662844 | Gallagher et al. | May 1987 | A |
4664631 | Pederson et al. | May 1987 | A |
4741154 | Eidelman | May 1988 | A |
5345758 | Bussing | Sep 1994 | A |
5430691 | Fridman | Jul 1995 | A |
5473885 | Hunter, Jr. et al. | Dec 1995 | A |
5513489 | Bussing | May 1996 | A |
5579633 | Hunter, Jr. et al. | Dec 1996 | A |
5644314 | Ahmad et al. | Jul 1997 | A |
5800153 | DeRoche | Sep 1998 | A |
5855827 | Bussing et al. | Jan 1999 | A |
5864517 | Hinkey et al. | Jan 1999 | A |
5873240 | Bussing et al. | Feb 1999 | A |
5937635 | Winfree et al. | Aug 1999 | A |
5973999 | Naff et al. | Oct 1999 | A |
6003301 | Bratkovich et al. | Dec 1999 | A |
6062018 | Bussing | May 2000 | A |
6360173 | Fullerton | Mar 2002 | B1 |
6408614 | Eizenhofer | Jun 2002 | B1 |
6813878 | Kraft | Nov 2004 | B2 |
6928804 | Venkataramani et al. | Aug 2005 | B2 |
7007455 | Kraft | Mar 2006 | B2 |
7093794 | Leyva et al. | Aug 2006 | B2 |
7100377 | Kraft | Sep 2006 | B2 |
20050125933 | Hochstein, Jr. et al. | Jun 2005 | A1 |
Number | Date | Country |
---|---|---|
934 749 | Aug 1963 | GB |
1 269 123 | Apr 1972 | GB |
Number | Date | Country | |
---|---|---|---|
20110000389 A1 | Jan 2011 | US |
Number | Date | Country | |
---|---|---|---|
60792420 | Apr 2006 | US | |
60850683 | Oct 2006 | US |