CA2037934A1 - Optical detonator - Google Patents
Optical detonatorInfo
- Publication number
- CA2037934A1 CA2037934A1 CA 2037934 CA2037934A CA2037934A1 CA 2037934 A1 CA2037934 A1 CA 2037934A1 CA 2037934 CA2037934 CA 2037934 CA 2037934 A CA2037934 A CA 2037934A CA 2037934 A1 CA2037934 A1 CA 2037934A1
- Authority
- CA
- Canada
- Prior art keywords
- detonator
- frequency converter
- converter element
- element means
- hollow body
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Abstract
11.
ABSTRACT.
The invention relates to an Optical Detonator comprising provision to accept a fibreoptic light guide cable 2 held by an attachable means within a elongated hollow body portion containing a frequency converter element means 6 placed intermediate said fibreoptic light guide cable terminal end 2 and a quantity of contained ex plosive material 9 placed adjacent the closed end of said elongated hollow body portion 1 of the detonator.
An electromagnetic radiation pulse sent down fibreoptic cable impings on the intermediately housed frequency converter element means 6 to be converted to infrared radiation energy to fire a "flashing" compound 7 to activate the explosive material 9 of the detonator.
ABSTRACT.
The invention relates to an Optical Detonator comprising provision to accept a fibreoptic light guide cable 2 held by an attachable means within a elongated hollow body portion containing a frequency converter element means 6 placed intermediate said fibreoptic light guide cable terminal end 2 and a quantity of contained ex plosive material 9 placed adjacent the closed end of said elongated hollow body portion 1 of the detonator.
An electromagnetic radiation pulse sent down fibreoptic cable impings on the intermediately housed frequency converter element means 6 to be converted to infrared radiation energy to fire a "flashing" compound 7 to activate the explosive material 9 of the detonator.
Description
3~934 1.
TITLE: OPTICAL DETONATOR
FIELD OF INVENTION
This invention is concerned with a detonator for explosive compositions and in particular to a detonator which is energi7ed by 5, electromagnetic radiation energy transmitted via a fibreoptic light guide cable or the like.
Although not widely practiced, the use of radiation energy trans-mitted by fibreoptic light cable for ~he detonation of explosives is widely known.
lO. Electrically actuated detonators comprising a thermo resistive element coated with an initiation or flashing compound are well known.
Such devices are inexpensive to manufacture and are known to be extreme-ly reliable in use with a re~onable safety factor in storage and hand-ling within defined parameters.
15, A major difficulty experienced with electrically actuated detonators is that they require connection to the detonating device via electrical conductive cables. Accidential explosions have been attributed to spurious electrical currents induced or conducted in the electrical cables by electrical machinery,static earth charges, lightning and the like.
20. In an en`deavour to avoid the use of electrically conductive cables between a detonator and a device supplying energy thereto for actuation, non electrically conductive fibreoptic cables have been proposed.
,` 7 ` ~ 203~3~
TITLE: OPTICAL DETONATOR
FIELD OF INVENTION
This invention is concerned with a detonator for explosive compositions and in particular to a detonator which is energi7ed by 5, electromagnetic radiation energy transmitted via a fibreoptic light guide cable or the like.
Although not widely practiced, the use of radiation energy trans-mitted by fibreoptic light cable for ~he detonation of explosives is widely known.
lO. Electrically actuated detonators comprising a thermo resistive element coated with an initiation or flashing compound are well known.
Such devices are inexpensive to manufacture and are known to be extreme-ly reliable in use with a re~onable safety factor in storage and hand-ling within defined parameters.
15, A major difficulty experienced with electrically actuated detonators is that they require connection to the detonating device via electrical conductive cables. Accidential explosions have been attributed to spurious electrical currents induced or conducted in the electrical cables by electrical machinery,static earth charges, lightning and the like.
20. In an en`deavour to avoid the use of electrically conductive cables between a detonator and a device supplying energy thereto for actuation, non electrically conductive fibreoptic cables have been proposed.
,` 7 ` ~ 203~3~
2.
Detonators employing fibre-optic ene~gy transmitters all suffer from two ma~or disadvantages - high cost and unreliability.
Uni~ed States Patent ~o. 3,408,937 describes-a S, laser actuated detonator having a fibre-optic cable terminating within a mass of pyrotechnic material or separated therefrom by a concentrating lens. In the forMer case laser energy emitting from the end of the fibre-optic cable impinges directly on the pyrotechnic material. As the 10. pyrotechnic material is inherently a poor heat conductor immense energy pulses are requixed to ignite the pyrotechnic ~aterial. It has been found that such immense ene~gy pulses can simply blast through the pyrotechnic material and as the duration of the pulse is so short, the heat energy is 15. dissipated in the pyrotechnic without causing ignition.
In the latter case the lens is considered to be ineffective as there is no optical pathway to focus the laser light when the pyrotechnic material is located against the face of the lens.
20. The detonator described in United States Patent No.
Detonators employing fibre-optic ene~gy transmitters all suffer from two ma~or disadvantages - high cost and unreliability.
Uni~ed States Patent ~o. 3,408,937 describes-a S, laser actuated detonator having a fibre-optic cable terminating within a mass of pyrotechnic material or separated therefrom by a concentrating lens. In the forMer case laser energy emitting from the end of the fibre-optic cable impinges directly on the pyrotechnic material. As the 10. pyrotechnic material is inherently a poor heat conductor immense energy pulses are requixed to ignite the pyrotechnic ~aterial. It has been found that such immense ene~gy pulses can simply blast through the pyrotechnic material and as the duration of the pulse is so short, the heat energy is 15. dissipated in the pyrotechnic without causing ignition.
In the latter case the lens is considered to be ineffective as there is no optical pathway to focus the laser light when the pyrotechnic material is located against the face of the lens.
20. The detonator described in United States Patent No.
3,408,937 requires an immense amount of laser energy to produce an ignition temperature of around 2000C in the pyrotechnic material, but this amount of energy in a short duration pulse is sufficient to se~ up a shock wave capable 25. of penetrating the pyrotechnic material without ignition. In a time delay detonator this can cause undesirable instant ~ :"
.
`` ~. 2~37934 B.
detonation of the explosive material in the detonator body.
Uni~ed States Patent No. 4,403,143 describes ~
detonating cord having a fibre-optic core formed therein. A
free end of the ~ibre-optic cord is fitted with a reflector 5. to enable continuity of the detonating cord to be checked.
The ~etonating cord is ignited by a conventional electrically actuated detonator.
United Sta~es Patent No. 4,391,195 describes a laser energy actuated detonator employing fibre-optic cable 10. to transmit the laser energy. The detonator described in this patent comprises a sensitive pyrotechnic material coated on the end of a fibre-optic cable adjacent the detonator charge compound or in direct contact therewith in a ~anner si~ilar to the detonator described in United States 15~ Patent No. 3,408,937 above.
The problems of poor heat absorption in the pyrotechnic material are addressed by incorporating an energy absorbing pigment or dyestuff with a highly sensitive pyrotechnic.
20. United States Patent No. 3,812,783 describes a laser actuated detonator comprising a focussing lens which .
focusses the laser energy on a metal film located on the opposite side of a transparent window. The laser energy causes the metal film to vaporize and cause a shock wave to 25. detonate explosive material in the detonator body United States Patent No. 3,747,530 recognizes the 2037g3~
problems associated with energy losses and unreliability of transmission of laser energy through transparent windows associated with optical fibres.
None of the prior art laser actuated detonators have been successful in combining the three distinctive features of prior art electrically SD actuated thermo resistive detonators in low cost, reliability and safety.
BROAD DESCRIPTION OF THE INVENTION
Accordin~lv it i5 the aim of the present invention to provide an inexpensive, easily constructed detonator which has a high degree of reliability and which is safe to handle and store and be able to be 10.produced at a marketable cost.
According to one aspect of the invention there is provided an optically actuable detonator comprising :
a elongated hollow body portion with a closed end containing a quantity of explosive material adjacent to said closed end ; and a 15.frequency converter element means located within the elongated hollow body portion, intermediate to a quantity of explosive material placed adjacent to the closed end, and an opening in the opposite end of said elongated hollow body portion adapted to receivably locate a terminal end of a fibreoptic light guide cable, said frequency converter element 20,means having a quantity of initiating pyrotechnic material located on one surface adjacent said explosive material.
If required ,a quantity of time delay pyrotechnic material may be located intermediate said initiating pyrotechnic material and said explosive material.
25. Preferably said frequency converter element means comprises a material capable of readily absorbing electromagnetic radiation and re-emmitting a large proportion of this radiation in the form of short wave infrared radiation.
The frequency converter element means may be composed of any of a 30.variety of materials or as combinations of these materials, such as metal, carbon, plastic or ceramic.
The frequency converter element means may be formed as a porous planar disc or as a closely woven fine gauge mesh screen, or arranged - `
as a element of thin walled material to which a coating or layer of 35. pyrotechnic material is attached or adhered to one surface of said frequ-ency converter element means with a blackened absorber surface on the side adjacent to the output end of a fibreoptic light guide cable.
Preferably said frequency converter element means comprises a material of low thermal conductivity.
-~ 2~3793~
5.
Most preferably said frequency converter element means comprises a wall of reduced thickness .
Suitably the frequency converter element means comprises aNi/Cr/Fe alloy such as stainless steel.
~, The frequency converter element means may be formed as a planar wall member within the elongated hollow body portion.
Most preferably said fr'quency converter element means has an adaptable means to locate the free end of a fibreoptic light cable entering the open end of said elongated hollow body portion.
10, Initiating pyrotechnic material is suitably located on said frequency converter element means in a position on the surface opposite the surface substantially aligned with the longitudonal axis of the adjacent position-ed output end of a fibreoptic light guide cable which is entered and held being co-axially aligned with casing of said elongated hollow body 15. portion.
The frquency converter element means may be held in place by securing to the wall of said elongated hollow body portion or may be located concentrically on the output end of fibreoptic light guide cable within the confines of the elongated hollow body portion.
20. ~uitably a prefered arrangement of the invention utilizes a freq-uency converter element means composed of a porous planar disc or as a element formed as a closely woven light gauge mesh screen composed of carb-on or carbon composition material or the like whereby a pyrotechnic material in the form of a thin coating or layer is attached or adhered 25. to one surface of the frequency converter element means.
An additional quantity of pyrotechnic fusing material may be placed in close proximity of said pyrotechnic coating of frequency~
element means to provide a more positive flashing means to ignite main explosive material. This additional material may provide a suitable 30. time delay means in firing detonator.
Frequency converter element means would be similiarly located and fixed as the befor~mentioned metal version of the device.
- ~ 2~3~9~ ~
DErAILED DESCRIPTION OF THE INVEN.TION.
: In order that t~e invention ~ay ~e ~ore clearly f S. understood, reference ls ~ade to preferred e~bodiments illustrated in the sccompanying drawings in which:- -FIGURE 1 lllustrates a cross sectional view of sne form of the invention;
~IGURE 2 illustrates an alternative for~ of the 10. invention; and FIGURE 3 illustrates yet another f~rm of the invention;
In FIGURE 1 the ~etonator comprises ~ thin walled metal body 1 of any suitable Metal ~uch as alumi~um, brass, 15. copper or the like.
A fi~re-opt~c cable 2 with a protective - _ _ - . covering - ~heath 3 i5 located in one end of body 1 by ~eans of a plug 4 which is fir~ly located by cri~ping the wall of body 1 adjacent each end of plug 4.
.
20. A thin walled frequency element ,~ 5 i~ frictionally engaged over the free end ~.f fibre optic cable 2, the inner .
end surface 6 of the cap being of a non-~eflective na~ure.
The end wall 6 may be a carbon absorber or may be compose~ of metal and have a non~reflective coating such as metal oxide formed by any suitable process.
25. The frequency converter element means may be formed sheet metal foil 20379~
7. ' or thin fiheet metal having a thickness in the range of O.01 ~m to 0.10 mm, preferably in the range of 0.03 mm to 0.06 mm.
Coated on the outer ~urface of cap 5 is an initiating pyrotechnic material 7 of conventional composition and ~uitably of the type employed in conventional electrically actuated thermo resistive detonators. Such compositions are of the deflagrating type wherein no substantial shattering of the crystal structure occurs during combustion. A similar material is applied to optional time delay component.
Deflagrating compositions typically are chosen from PETN, RDX tetryl, black powder, metal oxides, metallized polymers, various powdered fuels, high temperature and carbon oxidant mixtures. For the fusing means composition may include a binder such as a lacquer or the like, similar to the common electric detonator.
Spaced from the initiating pyrotechnic material 7 is an optional chemical time delay compound intimately placed against a high explosive compound 9 of a type suitable for detonation of a mass of explosive material such as dynamite, .~ .
gelignite, ANFAR explosive, annomium nitrate/fuel mixtures or the like.
The exposed free end of fibre-optic cable 2 (not shown) may be fitted with a conventional fibre-optic coupling device (also not shown~.
In use, the detonator of FIGURE 1 may be optically coupled to a suitable electxomagnetic radiation emission device capable of emitting an energy pulse sufficient to 30, heat cap 5 to emit a ~03~93~
~s ,; , ;
quantity of infra-red radiation which is enough to ignite pyrotechnic material 7.
For the detonator illustrated, a pulse energy of from 0. 2 to 0.4 joules is sufficient to ignite pyrstechnic 5. ~ materi~l 7 ~-.thout the risk of penetrating cap 5.
As the radiant energy pulse emits from the end of fibre optic cable 2 it impinges on the axially aligned face of cap S opposite pyrotechnic material 7. æhe relatiYely short wavelength energy is absorbed in cap 5 and is re-10. e~itted in the form of longex wave length infra-red radiation.As the material-~sed is a relatively poor conductor of heat, little heat loss due to conduction~o: other parts of cap 5 is encountered such that substantially only the irradiated region of cap 5 becomes heated.
15. By confirming ~hs heated region of cap 5 to a face opposite that upon which ~he pyrotechnic composition is adhered, the relatively thin wall of cap 5 allows heat to be concentrated and retained in the region of the pyrotechnic material 7 for a sufficient time and at a sufficient 20. intensity to ensure reliable ignition of the pyrotechnic material 7.
The operation of the optically actuated detonator described above may be considered as analogous to the reliable electrically actuated detona~ors which employ a 25, resistive metal filament to ignite the pyrotechnic material.
Prior art "optic' detonators in marked contrast `, ~37~3~ :
: 9. ~ -rely upon ignition of ~yrotechnic materials by direct impingement of optical radiation on a surface of the pyrotechnic material. The pyrotechnic matcrials are in themselves ineficient in converting optical energy to infra-5. red radiation as insufficient heat i~ gener~ted in the 5h~rt ~ nne ~ia~ giving rise to unreliable per~ormance.Atte~pts ~o improve reliability by utilizing higher energy pulses often cause penetration of the pyrotechnic material without ignition thereof.
10- FIGURE 2 shows an alternative embodiment of the detonator of FIGURE 1.
In FI~URE 2 the detonator comprises a time delay pyrotechnic material 8 of conventional type. ~he pyrotechnic material 8, when ignited by the initiating pyrotechnic 15. material 7, burns at a predetermined rate before detonating explosive material 9.
FIGURE 3 shows yet another form of the invention.
In this embodiment, the frequency converter 5 comprises a thin walled flequ~ncy converter element having a 20. central recess 5a to receive the end of fibre optic cable and a peripheral flange Sb which is frictionally located in body 1 by crimping or is otherwise located by any other suitable means.
The detonator may be manufactured with a suitable 25. length of fibre optic cable attached thereto, the free end of the fibre optic cable terminating in an optical coupling ` 20379~ -10. i; ', device.
Alternatively the detonator may be manufactured without a fi~re optic cable attached. The plug 4 may be made of a resilient polymeric material or other deformable 5. material uith a central cable receiving aperture. Over the end of plug 4 is a thin piercable closure 10 such as a plastics film or aluminum foil to protect the detonator against ingress of contaminants such as water, dirt etc.
In use the free end of a fibre optic-cable is 10. pushed through the closure 10 to pierce an aperture therein to pass through the opening as the aperture in plug 4 until the free end abuts against the inner wall 6 of cap 5.
~he resilient plug 4 ~irmly retains the fibre-optics cable In the variation described above, the use of 15. expensive fibre optics couplers may be avoided.
It will be clear to a skilled addressee that many modifications and variations may be made to the invention without departing from the spirit and scope thereof.
20. DATED this 4~ day of ~ ~P~
ARTUUR GEORGE YARRINGTON
.
`` ~. 2~37934 B.
detonation of the explosive material in the detonator body.
Uni~ed States Patent No. 4,403,143 describes ~
detonating cord having a fibre-optic core formed therein. A
free end of the ~ibre-optic cord is fitted with a reflector 5. to enable continuity of the detonating cord to be checked.
The ~etonating cord is ignited by a conventional electrically actuated detonator.
United Sta~es Patent No. 4,391,195 describes a laser energy actuated detonator employing fibre-optic cable 10. to transmit the laser energy. The detonator described in this patent comprises a sensitive pyrotechnic material coated on the end of a fibre-optic cable adjacent the detonator charge compound or in direct contact therewith in a ~anner si~ilar to the detonator described in United States 15~ Patent No. 3,408,937 above.
The problems of poor heat absorption in the pyrotechnic material are addressed by incorporating an energy absorbing pigment or dyestuff with a highly sensitive pyrotechnic.
20. United States Patent No. 3,812,783 describes a laser actuated detonator comprising a focussing lens which .
focusses the laser energy on a metal film located on the opposite side of a transparent window. The laser energy causes the metal film to vaporize and cause a shock wave to 25. detonate explosive material in the detonator body United States Patent No. 3,747,530 recognizes the 2037g3~
problems associated with energy losses and unreliability of transmission of laser energy through transparent windows associated with optical fibres.
None of the prior art laser actuated detonators have been successful in combining the three distinctive features of prior art electrically SD actuated thermo resistive detonators in low cost, reliability and safety.
BROAD DESCRIPTION OF THE INVENTION
Accordin~lv it i5 the aim of the present invention to provide an inexpensive, easily constructed detonator which has a high degree of reliability and which is safe to handle and store and be able to be 10.produced at a marketable cost.
According to one aspect of the invention there is provided an optically actuable detonator comprising :
a elongated hollow body portion with a closed end containing a quantity of explosive material adjacent to said closed end ; and a 15.frequency converter element means located within the elongated hollow body portion, intermediate to a quantity of explosive material placed adjacent to the closed end, and an opening in the opposite end of said elongated hollow body portion adapted to receivably locate a terminal end of a fibreoptic light guide cable, said frequency converter element 20,means having a quantity of initiating pyrotechnic material located on one surface adjacent said explosive material.
If required ,a quantity of time delay pyrotechnic material may be located intermediate said initiating pyrotechnic material and said explosive material.
25. Preferably said frequency converter element means comprises a material capable of readily absorbing electromagnetic radiation and re-emmitting a large proportion of this radiation in the form of short wave infrared radiation.
The frequency converter element means may be composed of any of a 30.variety of materials or as combinations of these materials, such as metal, carbon, plastic or ceramic.
The frequency converter element means may be formed as a porous planar disc or as a closely woven fine gauge mesh screen, or arranged - `
as a element of thin walled material to which a coating or layer of 35. pyrotechnic material is attached or adhered to one surface of said frequ-ency converter element means with a blackened absorber surface on the side adjacent to the output end of a fibreoptic light guide cable.
Preferably said frequency converter element means comprises a material of low thermal conductivity.
-~ 2~3793~
5.
Most preferably said frequency converter element means comprises a wall of reduced thickness .
Suitably the frequency converter element means comprises aNi/Cr/Fe alloy such as stainless steel.
~, The frequency converter element means may be formed as a planar wall member within the elongated hollow body portion.
Most preferably said fr'quency converter element means has an adaptable means to locate the free end of a fibreoptic light cable entering the open end of said elongated hollow body portion.
10, Initiating pyrotechnic material is suitably located on said frequency converter element means in a position on the surface opposite the surface substantially aligned with the longitudonal axis of the adjacent position-ed output end of a fibreoptic light guide cable which is entered and held being co-axially aligned with casing of said elongated hollow body 15. portion.
The frquency converter element means may be held in place by securing to the wall of said elongated hollow body portion or may be located concentrically on the output end of fibreoptic light guide cable within the confines of the elongated hollow body portion.
20. ~uitably a prefered arrangement of the invention utilizes a freq-uency converter element means composed of a porous planar disc or as a element formed as a closely woven light gauge mesh screen composed of carb-on or carbon composition material or the like whereby a pyrotechnic material in the form of a thin coating or layer is attached or adhered 25. to one surface of the frequency converter element means.
An additional quantity of pyrotechnic fusing material may be placed in close proximity of said pyrotechnic coating of frequency~
element means to provide a more positive flashing means to ignite main explosive material. This additional material may provide a suitable 30. time delay means in firing detonator.
Frequency converter element means would be similiarly located and fixed as the befor~mentioned metal version of the device.
- ~ 2~3~9~ ~
DErAILED DESCRIPTION OF THE INVEN.TION.
: In order that t~e invention ~ay ~e ~ore clearly f S. understood, reference ls ~ade to preferred e~bodiments illustrated in the sccompanying drawings in which:- -FIGURE 1 lllustrates a cross sectional view of sne form of the invention;
~IGURE 2 illustrates an alternative for~ of the 10. invention; and FIGURE 3 illustrates yet another f~rm of the invention;
In FIGURE 1 the ~etonator comprises ~ thin walled metal body 1 of any suitable Metal ~uch as alumi~um, brass, 15. copper or the like.
A fi~re-opt~c cable 2 with a protective - _ _ - . covering - ~heath 3 i5 located in one end of body 1 by ~eans of a plug 4 which is fir~ly located by cri~ping the wall of body 1 adjacent each end of plug 4.
.
20. A thin walled frequency element ,~ 5 i~ frictionally engaged over the free end ~.f fibre optic cable 2, the inner .
end surface 6 of the cap being of a non-~eflective na~ure.
The end wall 6 may be a carbon absorber or may be compose~ of metal and have a non~reflective coating such as metal oxide formed by any suitable process.
25. The frequency converter element means may be formed sheet metal foil 20379~
7. ' or thin fiheet metal having a thickness in the range of O.01 ~m to 0.10 mm, preferably in the range of 0.03 mm to 0.06 mm.
Coated on the outer ~urface of cap 5 is an initiating pyrotechnic material 7 of conventional composition and ~uitably of the type employed in conventional electrically actuated thermo resistive detonators. Such compositions are of the deflagrating type wherein no substantial shattering of the crystal structure occurs during combustion. A similar material is applied to optional time delay component.
Deflagrating compositions typically are chosen from PETN, RDX tetryl, black powder, metal oxides, metallized polymers, various powdered fuels, high temperature and carbon oxidant mixtures. For the fusing means composition may include a binder such as a lacquer or the like, similar to the common electric detonator.
Spaced from the initiating pyrotechnic material 7 is an optional chemical time delay compound intimately placed against a high explosive compound 9 of a type suitable for detonation of a mass of explosive material such as dynamite, .~ .
gelignite, ANFAR explosive, annomium nitrate/fuel mixtures or the like.
The exposed free end of fibre-optic cable 2 (not shown) may be fitted with a conventional fibre-optic coupling device (also not shown~.
In use, the detonator of FIGURE 1 may be optically coupled to a suitable electxomagnetic radiation emission device capable of emitting an energy pulse sufficient to 30, heat cap 5 to emit a ~03~93~
~s ,; , ;
quantity of infra-red radiation which is enough to ignite pyrotechnic material 7.
For the detonator illustrated, a pulse energy of from 0. 2 to 0.4 joules is sufficient to ignite pyrstechnic 5. ~ materi~l 7 ~-.thout the risk of penetrating cap 5.
As the radiant energy pulse emits from the end of fibre optic cable 2 it impinges on the axially aligned face of cap S opposite pyrotechnic material 7. æhe relatiYely short wavelength energy is absorbed in cap 5 and is re-10. e~itted in the form of longex wave length infra-red radiation.As the material-~sed is a relatively poor conductor of heat, little heat loss due to conduction~o: other parts of cap 5 is encountered such that substantially only the irradiated region of cap 5 becomes heated.
15. By confirming ~hs heated region of cap 5 to a face opposite that upon which ~he pyrotechnic composition is adhered, the relatively thin wall of cap 5 allows heat to be concentrated and retained in the region of the pyrotechnic material 7 for a sufficient time and at a sufficient 20. intensity to ensure reliable ignition of the pyrotechnic material 7.
The operation of the optically actuated detonator described above may be considered as analogous to the reliable electrically actuated detona~ors which employ a 25, resistive metal filament to ignite the pyrotechnic material.
Prior art "optic' detonators in marked contrast `, ~37~3~ :
: 9. ~ -rely upon ignition of ~yrotechnic materials by direct impingement of optical radiation on a surface of the pyrotechnic material. The pyrotechnic matcrials are in themselves ineficient in converting optical energy to infra-5. red radiation as insufficient heat i~ gener~ted in the 5h~rt ~ nne ~ia~ giving rise to unreliable per~ormance.Atte~pts ~o improve reliability by utilizing higher energy pulses often cause penetration of the pyrotechnic material without ignition thereof.
10- FIGURE 2 shows an alternative embodiment of the detonator of FIGURE 1.
In FI~URE 2 the detonator comprises a time delay pyrotechnic material 8 of conventional type. ~he pyrotechnic material 8, when ignited by the initiating pyrotechnic 15. material 7, burns at a predetermined rate before detonating explosive material 9.
FIGURE 3 shows yet another form of the invention.
In this embodiment, the frequency converter 5 comprises a thin walled flequ~ncy converter element having a 20. central recess 5a to receive the end of fibre optic cable and a peripheral flange Sb which is frictionally located in body 1 by crimping or is otherwise located by any other suitable means.
The detonator may be manufactured with a suitable 25. length of fibre optic cable attached thereto, the free end of the fibre optic cable terminating in an optical coupling ` 20379~ -10. i; ', device.
Alternatively the detonator may be manufactured without a fi~re optic cable attached. The plug 4 may be made of a resilient polymeric material or other deformable 5. material uith a central cable receiving aperture. Over the end of plug 4 is a thin piercable closure 10 such as a plastics film or aluminum foil to protect the detonator against ingress of contaminants such as water, dirt etc.
In use the free end of a fibre optic-cable is 10. pushed through the closure 10 to pierce an aperture therein to pass through the opening as the aperture in plug 4 until the free end abuts against the inner wall 6 of cap 5.
~he resilient plug 4 ~irmly retains the fibre-optics cable In the variation described above, the use of 15. expensive fibre optics couplers may be avoided.
It will be clear to a skilled addressee that many modifications and variations may be made to the invention without departing from the spirit and scope thereof.
20. DATED this 4~ day of ~ ~P~
ARTUUR GEORGE YARRINGTON
Claims (5)
1. A optical detonator comprising ;
[A] a elongated hollow body portion with a closed end containing a quantity of explosive material adjacent to said closed end; and [B] a frequency converter element means located within the elongated hollow body portion intermediate to a quantity of explosive material placed adjacent to the closed end, and an opening in the opposite end of said elongated hollow body portion adapted to receivably locate a terminal end of fibreoptic light guide cable, said frequency converter element means having [C] a quantity of initiating pyrotechnic material located on one surface adjacent said explosive material.
[A] a elongated hollow body portion with a closed end containing a quantity of explosive material adjacent to said closed end; and [B] a frequency converter element means located within the elongated hollow body portion intermediate to a quantity of explosive material placed adjacent to the closed end, and an opening in the opposite end of said elongated hollow body portion adapted to receivably locate a terminal end of fibreoptic light guide cable, said frequency converter element means having [C] a quantity of initiating pyrotechnic material located on one surface adjacent said explosive material.
2. A optical detonator as claimed in claim 1 wherein said frequency converter element means be composed of a material capable of readily absorbing electromagnetic radiation such as metal, carbon, carbon composi-tions , plastic and ceramic formed as a planar disc.
3. A optical detonator as claimed in claim 1 wherein said frequency converter element means be composed of a material capable of readily absorbing electromagnetic radiation such as metal ,carbon,carbon comp-ositions, plastic and ceramic formed as a planar disc as a closely woven fine gauge mesh screen.
4. A optical detonator as claimed in claim 1 wherein said frequency converter element means be composed of a metal such as stainless steel formed as a planar wall member within said elongated hollow body portion having a non reflective coating such as metal oxide formed on one surface adjacent to a fibreoptic light guide cable terminal end.
5. A optical detonator as in any of the proceeding claims and substantially as described and illustrated in the accompanying specifications and drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2037934 CA2037934A1 (en) | 1991-03-11 | 1991-03-11 | Optical detonator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2037934 CA2037934A1 (en) | 1991-03-11 | 1991-03-11 | Optical detonator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2037934A1 true CA2037934A1 (en) | 1992-09-12 |
Family
ID=4147160
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2037934 Abandoned CA2037934A1 (en) | 1991-03-11 | 1991-03-11 | Optical detonator |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2037934A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7810430B2 (en) | 2004-11-02 | 2010-10-12 | Orica Explosives Technology Pty Ltd | Wireless detonator assemblies, corresponding blasting apparatuses, and methods of blasting |
-
1991
- 1991-03-11 CA CA 2037934 patent/CA2037934A1/en not_active Abandoned
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7810430B2 (en) | 2004-11-02 | 2010-10-12 | Orica Explosives Technology Pty Ltd | Wireless detonator assemblies, corresponding blasting apparatuses, and methods of blasting |
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