CA1226044A - Electronic delay detonator - Google Patents
Electronic delay detonatorInfo
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- CA1226044A CA1226044A CA000452394A CA452394A CA1226044A CA 1226044 A CA1226044 A CA 1226044A CA 000452394 A CA000452394 A CA 000452394A CA 452394 A CA452394 A CA 452394A CA 1226044 A CA1226044 A CA 1226044A
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- electrical energy
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- delay detonator
- transistor
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Abstract
ABSTRACT OF THE DISCLOSURE
An electronic delay detonator actuated after the lapse of a predetermined delay time from the applica-tion of an input power source, comprises a capacitor for storing the electrical energy supplied from the input power source, a diode bridge for preventing the stored electrical energy from being released reversely toward the input power source, a CR oscillator, a counter for generating a signal upon having counted a pulse signal produced from the CR oscillator by a predetermined number, and a thruster driven by the signal for supplying the electrical energy stored in the capacitor to an ignition device in the detonator, the delay time being accurately determined by counting the pulses generated from the CR
oscillator.
An electronic delay detonator actuated after the lapse of a predetermined delay time from the applica-tion of an input power source, comprises a capacitor for storing the electrical energy supplied from the input power source, a diode bridge for preventing the stored electrical energy from being released reversely toward the input power source, a CR oscillator, a counter for generating a signal upon having counted a pulse signal produced from the CR oscillator by a predetermined number, and a thruster driven by the signal for supplying the electrical energy stored in the capacitor to an ignition device in the detonator, the delay time being accurately determined by counting the pulses generated from the CR
oscillator.
Description
4`
1 The present invention relates to an electronic delay detonator for delayed detonation after the lapse of a predetermined delay time in response to a pulse-like ignition input voltage.
The conventional electric delay detonator specie fled in JIG K4807 IRIS is an abbreviation of Japanese Industrial Standard) is such that delay powder is arranged between an electric ignition device (platinum wire) and a charge to delay the detonation time. The control of the oa~cl~r mixing of this delay wow and management of the charge I
amount thereof are very troublesome on the one hand, and the precision of the delay time is generally low on the other hand. In recent years, with the improved civil so s Jo engineering Tao wow, there has been an increasing demand for an improved time accuracy of the delay detonator.
So far, the accuracy of the electric delay detonator with delay powder has been limited to +3 to 4% of a set delay time.
In view of this, some researchers have suggested on 20 it electronic delay detonator with an electrical circuit which is low in production cost and high in time accuracy.
For technologies related to the electronic delay detonator, reference is made to Japanese Patent Laid-Open No. 43454/79 laid open on April 6, 1979, Japanese Patent Laid-Open No.
142496/82 laid open on September 3, 1982, Japanese Patent ~226~)ÇIL9L
1 Laid-Open No. 1~2~198/82 laid open on September 3, 1982, and US. Patent No. 4,240,350.
! These electronic delay detonators are roughly n classified into two types;Aanalog system comprising a time delay device including a series connection of a resistor and a capacitor in which the voltage across the capacitor is utilized, and a digital system comprising a OR oscilla-ion circuit or a crystal oscillator circuit and a counter so that the pulses generated by the oscillator circuit are counted to attain a predetermined delay time.
The former detonator generally comprises a capacitor for storing electrical energy, a thruster, an electrical ignition device (such as platinum wire) con-netted in series with the storage capacitor through the thruster, a series connection of a resistor and a keeps-ion for driving the thruster with a predetermined delay time after application of the electrical energy to the storage capacitor, a thruster trigger device inserted between the gate of the thruster and the time-delaying . .
capacitor for applying the electrical energy stored in the time-delaying capacitor to the gate of the thruster when the voltage across the time-delaying capacitor reaches a predetermined level, and a constant voltage circuit con-netted across the storage capacitor for applying a constant voltage across the time-delaying resistor and the keeps-ion regardless of the input voltage of the storage capacitor.
The electronic delay detonator with analog l voltage, however, has different delay times depending on the voltage applied to the storage capacitor and temper-azure changes, and has not any conspicuous advantage as - compared with the detonator with powder. Due to these facts and variations in electrical characteristics of parts to be used, it is difficult to produce such analog type detonators of practical use on a mass production basis.
Generally, the error of charge-discharge cycle under transient conditions increases with the capacitor S
capacity. If this error is to be reduced to minimum the capacitorScapacity should desirably be minimized. In the electronic delay detonator with analog voltage, however, the time delaying capacitor is used to determine the delay time, and also used to fire the thruster with the elect tribal energy stored therein. It is, therefore impossible a, to use ye capacitor of a capacity smaller than a predator-mined value, resulting in the problem of impossibility of error reduction and the problem of the unavailability of a wide setting range of delay time.
In the digital system aimed at high accuracy of delay time, on the other hand, it is common practice to use an oscillator circuit including an oscillator such as a crystal oscillator or a ceramic oscillator or a OR
oscillator circuit whereby the oscillation output is frequency-divided to effect accurate counting of the time.
The detonator with a OR oscillator has the problem of insufficient accuracy of the oscillation frequency, while 1 the oscillator circuit including a crystal oscillator or e I`' the like involves the following inconveniences in the delaying operation of the electronic delay detonator and is not of practical value. Specifically, the oscillation of a crystal oscillator or the like uses the vibrations by the mechanical displacement of a solid, and accordingly, it takes a long time such as several hundred milliseconds for the low-frequency oscillator or several tens of Millie seconds for the high-frequency oscillator before a pro-determined vibration frequency is established.
When one tries to delay the time accurately after the application of electrical ignition energy, therefore, the delay means using the crystal oscillator develops an error in delay time due to this initial unstable period of time, making it impossible to use the detonator reliably for delay blasting. If this initial unstable period is to be eliminated, it is necessary to excite the crystal oscil-later circuit with another power supply in advance. In delay firing or ignition of detonators where electrical ignition energy is applied to all the detonators at a time for sequential detonations, however, it is practically o impossible to supply stably necessary power per each detonator because power lines for the crystal oscillator circuits will be blasted and lost by explosion of a demo-NATO to be previously exploded. Further, the ordinary electric detonator utilizes two wires for supplying the electrical ignition energy to the detonator, and the detonator utilizing such crystal oscillator circuit which ~2~:61~4~ `
requires an additional wire for supplying power thereto will increase the wiring work cost and is not economical.
If the oscillation frequency of the crystal oscillator is increased to a higher level such as over several tens of MHz, it is true that the initial unstable period is shortened to several milliseconds. With an increased number of steps of ~requency-divider circuit for counting the delay time, however, the integrated circuits making up the frequency-dividing circuit is increased.
Accordingly, an object of the present invention is to provide an electronic delay detonator with an accurate delay time.
Another object of the present invention is to provide an electronic delay detonator in which the delay time can be set in a wide range.
Still another object of the present invention is to provide an electronic delay detonator which satisfies the requirements of compactness, low cost and high operating reliability.
According to one aspect of the present invention, there is provided an electronic delay detonator for driving an ignition device with a predetermined time delay by being supplied with electrical energy. The detonator comprises input terminal means for supplying the electrical energy to the delay detonator; a first capacitor for storing the electrical energy; means inserted between the input terminal means and the first capacitor for preventing the stored electrical energy from being released through the input oh ~26~)~4 terminal means; oscillator means electrically connected to the first capacitor and including a resistor and a second capacitor, for producing a plurality of pulse signals of a period proportional to the product of the resistance value of the resistor and the capacitance value of the second capacitor, the oscillator means also including a COOS
integrated circuit; means connected across the first capacitor for generating a constant voltage, the constant voltage generating means including a series connection of a diode-connected junction type field effect transistor and a zoner diode, the COOS integrated circuit being operated by the constant voltage generated across the zoner diode; means for counting the plurality of pulse signals and for producing a first signal upon counting the pulse signals up to a number corresponding to the predetermined delay time; and means responsive to the first signal for supplying the electrical energy stored in the first capacitor to the ignition device.
The features and advantages of the invention will be made apparent by the detailed description taken in conjunction with the accompanying drawings, in which:
Fig. 1 is a schematic diagram showing a circuit according to an embodiment of the present invention;
Figs. 2, PA and 3B are diagrams useful for explaining the embodiment of Fig. 1;
Fig. 4 is a schematic circuit diagram showing another embodiment of the present invention;
Fig. 5 is a diagram useful for explaining the embodiment of Fig. 4; and kh/jc ~LZ2~.4~
Fig. 6 is a diagram showing a schematic construction of an electronic delay detonator according to the present invention.
The present invention will now be explained in detail with reference to the various embodiments.
Embodiment 1:
A first embodiment of the invention is shown in Fig.
1. A diode bridge 11 includes diodes 12, 13 connected in series in a forward direction, and diodes 14, 15 also connected in series in a forward direction, the diode pairs - pa -oh . Jo 1, ... .
J, ,.
1 being connected in parallel to each other. The junction point of the diodes 12 and -I and the junction point of the diodes I and are connected to input terminals 16 and 17, respectively, while the junction point of diodes 13 and 15 and the junction point of the diodes 12 and 14 are connected to terminals 18 and 19, respectively. As a result, even if the connection between terminals 16, 17 and the positive and negative sides of a blasting machine, respectively, are interchanged, a positive voltage is always produced at the terminal 18. Also, even when the terminals 16 and 17 are shorted by an explosion, the charges of a capacitor 21 for storing electrical energy connected between the terminals 18 and 19 are prevented from being released to the terminals 16, 17.
The pulse-like power applied between the input terminals 16 end 17 is smoothed and stored in the capacitor 21. The terminal 18 is connected to a terminal of a junction-type field-effect transistor 22 for constant cur-rent source, the other terminal of which is connected, together with the gate thereof, to the terminal 19 through a plan~r-type zoner diode 23 for voltage regulation. In other words, the transistor 22 is diode-connected. The constant voltage produced from the junction point of the transistor 22 and the diode 23 is applied to the supply terminal of an integrated timer circuit I including an oscillator 100, a counter 101 and a counter reset circuit 102 made of COOS The oscillator 100 of the timer circuit 24 is connected with a resistor 25 for determining the 1 oscillation frequency and a temperature-compensated go-remake capacitor 26. Further, a reset capacitor 27 for preventing a counting error is connected to the reset terminal of the reset circuit 102 of the timer circuit 24.
This reset terminal is connected to the terminal 18 through a diode 28 for discharging the charges of the capacitor 27, in order to expedite the repetition test for delay time adjustment.
The terminal 18 is connected with the anode of the thruster 29 which serves as a delay pulse output supply switch. The cathode of the thruster 29 is connected to the terminal 19 through a load, that is, an ignition no-sister 31 of the electronic delay detonator. The gate of the thruster is connected through a buffer resistor 32 to the output terminal of the timer circuit 24 on the one hand, and to the terminal 19 through a noise-absorbing ceramic capacitor 33 on the other hand.
In this configuration, upon application of a pulse signal to be used as a source of an ignition energy for the electronic detonator between the terminals 16 and 17 from a blasting machine (not shown) as shown in Fig. PA, the voltage between the terminals 18 and 19 of the keeps-ion 21 is smoothed as shown in Fig. 2B, which voltage is applied, as a constant voltage as shown in Fig. 2C, through the transistor 22 and diode 23, to the supply terminal of the timer circuit 24. As a result, the timer circuit is actuated and begins to oscillate at a period determined by the time constant of the capacitor 26 connected in 1 series with thy resistor 25.
This waveform of oscillation is, for example, as shown in Figs. PA and 3B, in which wren the capacity of the capacitor 26 is large, the period To lengthens as shown in Fig. PA, while if the capacity of the capacitor 26 is small, the period To is shortened as shown in Fig.
3B. This oscillation signal is counted by the counter 101 in the timer circuit 24, and when the count reaches a predetermined value, that is, when a set-up time is 0 reached, a set-up signal used for driving the thruster pr(~d~c~d 29 is p~4d~i6ed from the output terminal of the timer air-cult 24, so that the thruster 29 is turned on, and the charges of the capacitor 21 are applied through the Theresa-ion I in pulse form to the ignition resistor 31 as shown in Fig. ED. The time I from the application of the pulse signal forming the energy source of ignition of the elect ironic detonator to the application of the pulse to the ignition resistor 31 makes up a delay time.
When the potential charged to the capacitor 26 reaches a threshold potential VT or VT" of an active switching element in the oscillator 100, the oscillation is turned on by the charge-discharge of the capacitor I
so that the charges are rapidly released from the keeps-ion 26. As a result, the active switching element is turned off again, so that the charging is resumed. This operation causes continued oscillation, thereby producing an oscillation waveform as shown in Fig. PA ox Fig. 3B.
In Figs. PA and 3B, VT designates a threshold value _ 9 I isle,; .
1 obtained when a comparatively large-capacity capacitor is used as the capacitor 26, and VT" that obtained when a capacitor of a comparatively small capacitance is used as the capacitor 26. The charges in the capacitor 26 are not completely released due to the internal resistance of the capacitor 26 even at the time of shorting, that is, upon turning on of the active switching element, and is normally charged again when the off-threshold value of the active switching element is reached. US and Us'' in Figs. PA and 3B represent the off-threshold values (potential of reside vat charges) corresponding to the large-capacity capacitor 26 and the small-capacity capacitor 26, and in this case, Us'' is smaller than Vs. When the capacity of the keeps-ion 26 is especially large, the discharge current in-creases to such a degree that variations of ON-resistance of the active switching element poses a very great cause of error. Also, the source voltage-caused drift and the temperature-caused drift of the threshold voltage of the active switching element are another cause of an error in variation of oscillation frequency.
The embodiment under consideration is intended to realize a stable OR oscillator circuit operating on the basis of repetition of charge-discharge of the capacitor, which has so far been considered not very practical due to many factors of instability. It is conventionally known that such active switching elements as a bipolar transistor and a thruster undergo a drift of threshold potential with temperature or voltage. The OR oscillation, I
1 which generally lacks the frequency stability, is not used in important applications. Nevertheless, the stability of threshold voltage of the COOS circuit element (couple-Monterey field-effect transistor) has been remarkably imp proved as compared with the conventional active devices since the COOS circuit element, with its low power con-gumption, is such that the P-channel and N-channel field-effect transistors function in complementary manner, and especially, the threshold voltages ox the P-channel and N-channel field-effect transistors have opposite tempera-lure coefficients to each other. And further, in view of the field-effect transistor being a voltage-controlled device, the change of the threshold voltage due to the change of the source voltage is not dependent upon the change of resistance of the P- and N-channel Eield-effect transistors and is fixed almost to one half of the source voltage, unlike the conventional switch circuits with a bipolar transistor.
In this embodiment, the timer circuit 24 formed I of COOS circuit elements with an improved stability as compared with the above-mentioned active elements is use, with the result that stable operation is attained over wide ranges of temperature and input pulse voltage with high delay lime accuracy.
Also, according to this embodiment, the capacitor 26 is used only to determine the oscillation frequency, and therefore it is possible to use a small-capacity capacitor so that the range of capacity selection thereof :~26~
.
1 is not limited or the circuit function is not affected by the variations in ON-resistance of the active switching element in the oscillator 100. As a result, the delay time ma be determined accurately over a wide range. The setting of the delay time may be effected by changing the values of the capacitor and/or the resistor 26.
For the reason mentioned above, the capacity of the capacitor 26 is desirably small. If the circuit portion is sealed with epoxy resin or the like, however, the floating capacity and the capacity between capacitor terminals would be greatly affected, thus making it dip-faculty to determine a constant charqe-discharge oscilla-lion frequency of the capacitor and resistor.
According to the present invention, the capacity of the capacitor need not be very small but may be chosen such that the discharge current from the capacitor lies within the discharge current range of the active elements combined therewith, thus permitting the setting of the delay time over a wide range. In this embodiment, the capacitance of the capacitor 26 may preferably lie in the range of about 100 to 1000 pi.
In the present embodiment, the junction-type field-effect transistor 22 and the zoner diode 23 maze up a voltage-regulation circuit. On the other hand, a conventional circuit uses a resistor and a zoner diode, which has the disadvantage of unstable operation due to the current change depending upon the applied voltage there across. In an improvement of this circuit a :~260~4 .
1 field-effect transistor is used as a constant-current element. In a combination of a MOW field-effect transit-ion and a zoner diode, however, the disadvantage of temperature dependency is not eliminated in spite ox the advantage of some effect of constant current obtained.
According to the present invention, this short-coming has been obviated by a combination of a ever diode and a junction-type field-effect transistor as a voltage-regulation circuit. Specifically, the gate-source voltage of a junction-type field effect transistor 22 is set in an region where the drain current is stable against temper-azure change and, as a minor constant-current source, a planer-type zoner diode 23 of about TV comparatively stable with temperature change is combined, so that the operation of the timer circuit 24 is stabilized with an improved time accuracy on the one hand, and the capacity of the capacitor 21 is reduced by employing the drain current of lima or less for an increased pulse energy on the other hand.
Further, since the COO timer circuit 24 with a small current consumption is used, the blasting machine (electrical energy source) need not be specially bulky as compared with TTL and may be powered by a layer-built dry cell or the like. Also, the pulse signal to be used as a power source is used for both power source of the timer circuit 24 and the ignition energy of the ignition no-sister 31 without increasing the capacity of the keeps-ion 21.
1 Embodiment 2:
The ignition of the electric detonator is usual-lye made instantaneously with electrical pulse energy. The switch elements such as a thruster are susceptible to noises of small pulse width generated under transient conditions.
With reference to Figs. PA and 5B, upon applique-lion to the electric detonator of a pulse signal maying up an energy source for ignition of the electric detonator, a noise is superimposed on the pulse signal as shown in Fig. PA, for instance, which often causes a number of noises of small pulse width in the voltage across the capacitor 21 as shown in Fig. 5B. Therefore, if the gate ox the thruster 29 is loft open, these pulse noises may erroneously turn it on, thus erroneously supplying output energy to the ignition resistor 31.
To eliminate this inconvenience, it is desirable to short the gate terminal of the thruster 29 with a high-speed switching element at the time of applying the pulse signal making up an energy source.
The embodiment shown in Fig. 4 takes this idea into consideration. Those component elements in Fig. 1 which are similar to those in Fig. 1 designated with similar numerals are not described again. As shown in Fig. 4, the base of a high-speed switching transistor 34 is connected with the terminal 18 through an impedance element 35 such as a capacitor, the collector thereof to the gate to the thruster 29, and the emitter thereof to I
s eye 1 the terminal 19. Upon application ox power, the stying transistor 34 is turned on so that the gate of the Theresa-a ion 29 is shorted, and after the lapse of unstable period of time To (Fig. 5), the transistor 34 is turned off to place the gate of the thruster 29 in a respective mode.
In this way, stable operation is secured even against the noises generated by the rapid rise or the like of the pulse signal. In Fig. 4, a diode 36 is inserted between the terminal 18 and the junction point of the capacitor 21 and the transistor 22.
According to the present invention, it is possible to provide a compact, low-cost delay detonator with stable time accuracy, as compared with the convent tonal delay detonators with delay powder. If the delay pulse generator circuit 37 is integrated with the Dayton-ion, an LSI including an integration of a COOS oscillator circuit and a frequency-divider circuit or a counter air-cult may be combined with a chip capacitor, a chip no-sister, a mini mold transistor, a mini mold thruster, a mini mold zoner diode and a mini mold field effect tray-sister to obtain a hybrid configuration, thus making it possible to contain the circuit devices in a compact body of the electric detonator which is comparable in size with the conventional delay detonators widely used.
As the timer circuit 24, M58482P or MYOPIA of Mitsubishi Electric Corporation or TC5043C of Toshiba Corporation may be used.
An example in which the delay pulse generator ~226~4LÇgL
1 circuit is incorporated in the electric detonator is shown in Fig. 6. Specifically, a base charge 43 is in-sorted into a shell 39 with a closed end. The primer charge 42 contained in the inner capsule 41 is inserted into the shell 39. After some time interval the pulse generator 37 with a delay pulse generator circuit such as shown in Figs. 1 or 4 built therein is inserted into the shell 39. The ignition resistor 31 made of an resistor wire is arranged on the initiator or primer charge 42 side of the pulse generator 37, and ignition device made of an ignition powder 40 is attached to the ignition resistor 31. Leg wires 38 are led out from the outer end of the pulse generator 37.
1 The present invention relates to an electronic delay detonator for delayed detonation after the lapse of a predetermined delay time in response to a pulse-like ignition input voltage.
The conventional electric delay detonator specie fled in JIG K4807 IRIS is an abbreviation of Japanese Industrial Standard) is such that delay powder is arranged between an electric ignition device (platinum wire) and a charge to delay the detonation time. The control of the oa~cl~r mixing of this delay wow and management of the charge I
amount thereof are very troublesome on the one hand, and the precision of the delay time is generally low on the other hand. In recent years, with the improved civil so s Jo engineering Tao wow, there has been an increasing demand for an improved time accuracy of the delay detonator.
So far, the accuracy of the electric delay detonator with delay powder has been limited to +3 to 4% of a set delay time.
In view of this, some researchers have suggested on 20 it electronic delay detonator with an electrical circuit which is low in production cost and high in time accuracy.
For technologies related to the electronic delay detonator, reference is made to Japanese Patent Laid-Open No. 43454/79 laid open on April 6, 1979, Japanese Patent Laid-Open No.
142496/82 laid open on September 3, 1982, Japanese Patent ~226~)ÇIL9L
1 Laid-Open No. 1~2~198/82 laid open on September 3, 1982, and US. Patent No. 4,240,350.
! These electronic delay detonators are roughly n classified into two types;Aanalog system comprising a time delay device including a series connection of a resistor and a capacitor in which the voltage across the capacitor is utilized, and a digital system comprising a OR oscilla-ion circuit or a crystal oscillator circuit and a counter so that the pulses generated by the oscillator circuit are counted to attain a predetermined delay time.
The former detonator generally comprises a capacitor for storing electrical energy, a thruster, an electrical ignition device (such as platinum wire) con-netted in series with the storage capacitor through the thruster, a series connection of a resistor and a keeps-ion for driving the thruster with a predetermined delay time after application of the electrical energy to the storage capacitor, a thruster trigger device inserted between the gate of the thruster and the time-delaying . .
capacitor for applying the electrical energy stored in the time-delaying capacitor to the gate of the thruster when the voltage across the time-delaying capacitor reaches a predetermined level, and a constant voltage circuit con-netted across the storage capacitor for applying a constant voltage across the time-delaying resistor and the keeps-ion regardless of the input voltage of the storage capacitor.
The electronic delay detonator with analog l voltage, however, has different delay times depending on the voltage applied to the storage capacitor and temper-azure changes, and has not any conspicuous advantage as - compared with the detonator with powder. Due to these facts and variations in electrical characteristics of parts to be used, it is difficult to produce such analog type detonators of practical use on a mass production basis.
Generally, the error of charge-discharge cycle under transient conditions increases with the capacitor S
capacity. If this error is to be reduced to minimum the capacitorScapacity should desirably be minimized. In the electronic delay detonator with analog voltage, however, the time delaying capacitor is used to determine the delay time, and also used to fire the thruster with the elect tribal energy stored therein. It is, therefore impossible a, to use ye capacitor of a capacity smaller than a predator-mined value, resulting in the problem of impossibility of error reduction and the problem of the unavailability of a wide setting range of delay time.
In the digital system aimed at high accuracy of delay time, on the other hand, it is common practice to use an oscillator circuit including an oscillator such as a crystal oscillator or a ceramic oscillator or a OR
oscillator circuit whereby the oscillation output is frequency-divided to effect accurate counting of the time.
The detonator with a OR oscillator has the problem of insufficient accuracy of the oscillation frequency, while 1 the oscillator circuit including a crystal oscillator or e I`' the like involves the following inconveniences in the delaying operation of the electronic delay detonator and is not of practical value. Specifically, the oscillation of a crystal oscillator or the like uses the vibrations by the mechanical displacement of a solid, and accordingly, it takes a long time such as several hundred milliseconds for the low-frequency oscillator or several tens of Millie seconds for the high-frequency oscillator before a pro-determined vibration frequency is established.
When one tries to delay the time accurately after the application of electrical ignition energy, therefore, the delay means using the crystal oscillator develops an error in delay time due to this initial unstable period of time, making it impossible to use the detonator reliably for delay blasting. If this initial unstable period is to be eliminated, it is necessary to excite the crystal oscil-later circuit with another power supply in advance. In delay firing or ignition of detonators where electrical ignition energy is applied to all the detonators at a time for sequential detonations, however, it is practically o impossible to supply stably necessary power per each detonator because power lines for the crystal oscillator circuits will be blasted and lost by explosion of a demo-NATO to be previously exploded. Further, the ordinary electric detonator utilizes two wires for supplying the electrical ignition energy to the detonator, and the detonator utilizing such crystal oscillator circuit which ~2~:61~4~ `
requires an additional wire for supplying power thereto will increase the wiring work cost and is not economical.
If the oscillation frequency of the crystal oscillator is increased to a higher level such as over several tens of MHz, it is true that the initial unstable period is shortened to several milliseconds. With an increased number of steps of ~requency-divider circuit for counting the delay time, however, the integrated circuits making up the frequency-dividing circuit is increased.
Accordingly, an object of the present invention is to provide an electronic delay detonator with an accurate delay time.
Another object of the present invention is to provide an electronic delay detonator in which the delay time can be set in a wide range.
Still another object of the present invention is to provide an electronic delay detonator which satisfies the requirements of compactness, low cost and high operating reliability.
According to one aspect of the present invention, there is provided an electronic delay detonator for driving an ignition device with a predetermined time delay by being supplied with electrical energy. The detonator comprises input terminal means for supplying the electrical energy to the delay detonator; a first capacitor for storing the electrical energy; means inserted between the input terminal means and the first capacitor for preventing the stored electrical energy from being released through the input oh ~26~)~4 terminal means; oscillator means electrically connected to the first capacitor and including a resistor and a second capacitor, for producing a plurality of pulse signals of a period proportional to the product of the resistance value of the resistor and the capacitance value of the second capacitor, the oscillator means also including a COOS
integrated circuit; means connected across the first capacitor for generating a constant voltage, the constant voltage generating means including a series connection of a diode-connected junction type field effect transistor and a zoner diode, the COOS integrated circuit being operated by the constant voltage generated across the zoner diode; means for counting the plurality of pulse signals and for producing a first signal upon counting the pulse signals up to a number corresponding to the predetermined delay time; and means responsive to the first signal for supplying the electrical energy stored in the first capacitor to the ignition device.
The features and advantages of the invention will be made apparent by the detailed description taken in conjunction with the accompanying drawings, in which:
Fig. 1 is a schematic diagram showing a circuit according to an embodiment of the present invention;
Figs. 2, PA and 3B are diagrams useful for explaining the embodiment of Fig. 1;
Fig. 4 is a schematic circuit diagram showing another embodiment of the present invention;
Fig. 5 is a diagram useful for explaining the embodiment of Fig. 4; and kh/jc ~LZ2~.4~
Fig. 6 is a diagram showing a schematic construction of an electronic delay detonator according to the present invention.
The present invention will now be explained in detail with reference to the various embodiments.
Embodiment 1:
A first embodiment of the invention is shown in Fig.
1. A diode bridge 11 includes diodes 12, 13 connected in series in a forward direction, and diodes 14, 15 also connected in series in a forward direction, the diode pairs - pa -oh . Jo 1, ... .
J, ,.
1 being connected in parallel to each other. The junction point of the diodes 12 and -I and the junction point of the diodes I and are connected to input terminals 16 and 17, respectively, while the junction point of diodes 13 and 15 and the junction point of the diodes 12 and 14 are connected to terminals 18 and 19, respectively. As a result, even if the connection between terminals 16, 17 and the positive and negative sides of a blasting machine, respectively, are interchanged, a positive voltage is always produced at the terminal 18. Also, even when the terminals 16 and 17 are shorted by an explosion, the charges of a capacitor 21 for storing electrical energy connected between the terminals 18 and 19 are prevented from being released to the terminals 16, 17.
The pulse-like power applied between the input terminals 16 end 17 is smoothed and stored in the capacitor 21. The terminal 18 is connected to a terminal of a junction-type field-effect transistor 22 for constant cur-rent source, the other terminal of which is connected, together with the gate thereof, to the terminal 19 through a plan~r-type zoner diode 23 for voltage regulation. In other words, the transistor 22 is diode-connected. The constant voltage produced from the junction point of the transistor 22 and the diode 23 is applied to the supply terminal of an integrated timer circuit I including an oscillator 100, a counter 101 and a counter reset circuit 102 made of COOS The oscillator 100 of the timer circuit 24 is connected with a resistor 25 for determining the 1 oscillation frequency and a temperature-compensated go-remake capacitor 26. Further, a reset capacitor 27 for preventing a counting error is connected to the reset terminal of the reset circuit 102 of the timer circuit 24.
This reset terminal is connected to the terminal 18 through a diode 28 for discharging the charges of the capacitor 27, in order to expedite the repetition test for delay time adjustment.
The terminal 18 is connected with the anode of the thruster 29 which serves as a delay pulse output supply switch. The cathode of the thruster 29 is connected to the terminal 19 through a load, that is, an ignition no-sister 31 of the electronic delay detonator. The gate of the thruster is connected through a buffer resistor 32 to the output terminal of the timer circuit 24 on the one hand, and to the terminal 19 through a noise-absorbing ceramic capacitor 33 on the other hand.
In this configuration, upon application of a pulse signal to be used as a source of an ignition energy for the electronic detonator between the terminals 16 and 17 from a blasting machine (not shown) as shown in Fig. PA, the voltage between the terminals 18 and 19 of the keeps-ion 21 is smoothed as shown in Fig. 2B, which voltage is applied, as a constant voltage as shown in Fig. 2C, through the transistor 22 and diode 23, to the supply terminal of the timer circuit 24. As a result, the timer circuit is actuated and begins to oscillate at a period determined by the time constant of the capacitor 26 connected in 1 series with thy resistor 25.
This waveform of oscillation is, for example, as shown in Figs. PA and 3B, in which wren the capacity of the capacitor 26 is large, the period To lengthens as shown in Fig. PA, while if the capacity of the capacitor 26 is small, the period To is shortened as shown in Fig.
3B. This oscillation signal is counted by the counter 101 in the timer circuit 24, and when the count reaches a predetermined value, that is, when a set-up time is 0 reached, a set-up signal used for driving the thruster pr(~d~c~d 29 is p~4d~i6ed from the output terminal of the timer air-cult 24, so that the thruster 29 is turned on, and the charges of the capacitor 21 are applied through the Theresa-ion I in pulse form to the ignition resistor 31 as shown in Fig. ED. The time I from the application of the pulse signal forming the energy source of ignition of the elect ironic detonator to the application of the pulse to the ignition resistor 31 makes up a delay time.
When the potential charged to the capacitor 26 reaches a threshold potential VT or VT" of an active switching element in the oscillator 100, the oscillation is turned on by the charge-discharge of the capacitor I
so that the charges are rapidly released from the keeps-ion 26. As a result, the active switching element is turned off again, so that the charging is resumed. This operation causes continued oscillation, thereby producing an oscillation waveform as shown in Fig. PA ox Fig. 3B.
In Figs. PA and 3B, VT designates a threshold value _ 9 I isle,; .
1 obtained when a comparatively large-capacity capacitor is used as the capacitor 26, and VT" that obtained when a capacitor of a comparatively small capacitance is used as the capacitor 26. The charges in the capacitor 26 are not completely released due to the internal resistance of the capacitor 26 even at the time of shorting, that is, upon turning on of the active switching element, and is normally charged again when the off-threshold value of the active switching element is reached. US and Us'' in Figs. PA and 3B represent the off-threshold values (potential of reside vat charges) corresponding to the large-capacity capacitor 26 and the small-capacity capacitor 26, and in this case, Us'' is smaller than Vs. When the capacity of the keeps-ion 26 is especially large, the discharge current in-creases to such a degree that variations of ON-resistance of the active switching element poses a very great cause of error. Also, the source voltage-caused drift and the temperature-caused drift of the threshold voltage of the active switching element are another cause of an error in variation of oscillation frequency.
The embodiment under consideration is intended to realize a stable OR oscillator circuit operating on the basis of repetition of charge-discharge of the capacitor, which has so far been considered not very practical due to many factors of instability. It is conventionally known that such active switching elements as a bipolar transistor and a thruster undergo a drift of threshold potential with temperature or voltage. The OR oscillation, I
1 which generally lacks the frequency stability, is not used in important applications. Nevertheless, the stability of threshold voltage of the COOS circuit element (couple-Monterey field-effect transistor) has been remarkably imp proved as compared with the conventional active devices since the COOS circuit element, with its low power con-gumption, is such that the P-channel and N-channel field-effect transistors function in complementary manner, and especially, the threshold voltages ox the P-channel and N-channel field-effect transistors have opposite tempera-lure coefficients to each other. And further, in view of the field-effect transistor being a voltage-controlled device, the change of the threshold voltage due to the change of the source voltage is not dependent upon the change of resistance of the P- and N-channel Eield-effect transistors and is fixed almost to one half of the source voltage, unlike the conventional switch circuits with a bipolar transistor.
In this embodiment, the timer circuit 24 formed I of COOS circuit elements with an improved stability as compared with the above-mentioned active elements is use, with the result that stable operation is attained over wide ranges of temperature and input pulse voltage with high delay lime accuracy.
Also, according to this embodiment, the capacitor 26 is used only to determine the oscillation frequency, and therefore it is possible to use a small-capacity capacitor so that the range of capacity selection thereof :~26~
.
1 is not limited or the circuit function is not affected by the variations in ON-resistance of the active switching element in the oscillator 100. As a result, the delay time ma be determined accurately over a wide range. The setting of the delay time may be effected by changing the values of the capacitor and/or the resistor 26.
For the reason mentioned above, the capacity of the capacitor 26 is desirably small. If the circuit portion is sealed with epoxy resin or the like, however, the floating capacity and the capacity between capacitor terminals would be greatly affected, thus making it dip-faculty to determine a constant charqe-discharge oscilla-lion frequency of the capacitor and resistor.
According to the present invention, the capacity of the capacitor need not be very small but may be chosen such that the discharge current from the capacitor lies within the discharge current range of the active elements combined therewith, thus permitting the setting of the delay time over a wide range. In this embodiment, the capacitance of the capacitor 26 may preferably lie in the range of about 100 to 1000 pi.
In the present embodiment, the junction-type field-effect transistor 22 and the zoner diode 23 maze up a voltage-regulation circuit. On the other hand, a conventional circuit uses a resistor and a zoner diode, which has the disadvantage of unstable operation due to the current change depending upon the applied voltage there across. In an improvement of this circuit a :~260~4 .
1 field-effect transistor is used as a constant-current element. In a combination of a MOW field-effect transit-ion and a zoner diode, however, the disadvantage of temperature dependency is not eliminated in spite ox the advantage of some effect of constant current obtained.
According to the present invention, this short-coming has been obviated by a combination of a ever diode and a junction-type field-effect transistor as a voltage-regulation circuit. Specifically, the gate-source voltage of a junction-type field effect transistor 22 is set in an region where the drain current is stable against temper-azure change and, as a minor constant-current source, a planer-type zoner diode 23 of about TV comparatively stable with temperature change is combined, so that the operation of the timer circuit 24 is stabilized with an improved time accuracy on the one hand, and the capacity of the capacitor 21 is reduced by employing the drain current of lima or less for an increased pulse energy on the other hand.
Further, since the COO timer circuit 24 with a small current consumption is used, the blasting machine (electrical energy source) need not be specially bulky as compared with TTL and may be powered by a layer-built dry cell or the like. Also, the pulse signal to be used as a power source is used for both power source of the timer circuit 24 and the ignition energy of the ignition no-sister 31 without increasing the capacity of the keeps-ion 21.
1 Embodiment 2:
The ignition of the electric detonator is usual-lye made instantaneously with electrical pulse energy. The switch elements such as a thruster are susceptible to noises of small pulse width generated under transient conditions.
With reference to Figs. PA and 5B, upon applique-lion to the electric detonator of a pulse signal maying up an energy source for ignition of the electric detonator, a noise is superimposed on the pulse signal as shown in Fig. PA, for instance, which often causes a number of noises of small pulse width in the voltage across the capacitor 21 as shown in Fig. 5B. Therefore, if the gate ox the thruster 29 is loft open, these pulse noises may erroneously turn it on, thus erroneously supplying output energy to the ignition resistor 31.
To eliminate this inconvenience, it is desirable to short the gate terminal of the thruster 29 with a high-speed switching element at the time of applying the pulse signal making up an energy source.
The embodiment shown in Fig. 4 takes this idea into consideration. Those component elements in Fig. 1 which are similar to those in Fig. 1 designated with similar numerals are not described again. As shown in Fig. 4, the base of a high-speed switching transistor 34 is connected with the terminal 18 through an impedance element 35 such as a capacitor, the collector thereof to the gate to the thruster 29, and the emitter thereof to I
s eye 1 the terminal 19. Upon application ox power, the stying transistor 34 is turned on so that the gate of the Theresa-a ion 29 is shorted, and after the lapse of unstable period of time To (Fig. 5), the transistor 34 is turned off to place the gate of the thruster 29 in a respective mode.
In this way, stable operation is secured even against the noises generated by the rapid rise or the like of the pulse signal. In Fig. 4, a diode 36 is inserted between the terminal 18 and the junction point of the capacitor 21 and the transistor 22.
According to the present invention, it is possible to provide a compact, low-cost delay detonator with stable time accuracy, as compared with the convent tonal delay detonators with delay powder. If the delay pulse generator circuit 37 is integrated with the Dayton-ion, an LSI including an integration of a COOS oscillator circuit and a frequency-divider circuit or a counter air-cult may be combined with a chip capacitor, a chip no-sister, a mini mold transistor, a mini mold thruster, a mini mold zoner diode and a mini mold field effect tray-sister to obtain a hybrid configuration, thus making it possible to contain the circuit devices in a compact body of the electric detonator which is comparable in size with the conventional delay detonators widely used.
As the timer circuit 24, M58482P or MYOPIA of Mitsubishi Electric Corporation or TC5043C of Toshiba Corporation may be used.
An example in which the delay pulse generator ~226~4LÇgL
1 circuit is incorporated in the electric detonator is shown in Fig. 6. Specifically, a base charge 43 is in-sorted into a shell 39 with a closed end. The primer charge 42 contained in the inner capsule 41 is inserted into the shell 39. After some time interval the pulse generator 37 with a delay pulse generator circuit such as shown in Figs. 1 or 4 built therein is inserted into the shell 39. The ignition resistor 31 made of an resistor wire is arranged on the initiator or primer charge 42 side of the pulse generator 37, and ignition device made of an ignition powder 40 is attached to the ignition resistor 31. Leg wires 38 are led out from the outer end of the pulse generator 37.
Claims (12)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An electronic delay detonator for driving an ignition device with a predetermined time delay by being supplied with electrical energy, comprising:
input terminal means for supplying the electrical energy to said delay detonator;
a first capacitor for storing said electrical energy;
means inserted between said input terminal means and said first capacitor for preventing said stored electrical energy from being released through said input terminal means;
oscillator means electrically connected to said first capacitor and including a resistor and a second capacitor, for producing a plurality of pulse signals of a period proportional to the product of the resistance value of said resistor and the capacitance value of said second capacitor, said oscillator means also including a C-MOS
integrated circuit;
means connected across said first capacitor for generating a constant voltage, said constant voltage generating means including a series connection of a diode-connected junction-type field effect transistor and a zener diode, said C-MOS integrated circuit being operated by said constant voltage generated across said zener diode;
means for counting said plurality of pulse signals and for producing a first signal upon counting said pulse signals up to a number corresponding to said predetermined delay time; and means responsive to said first signal for supplying the electrical energy stored in said first capacitor to said ignition device.
input terminal means for supplying the electrical energy to said delay detonator;
a first capacitor for storing said electrical energy;
means inserted between said input terminal means and said first capacitor for preventing said stored electrical energy from being released through said input terminal means;
oscillator means electrically connected to said first capacitor and including a resistor and a second capacitor, for producing a plurality of pulse signals of a period proportional to the product of the resistance value of said resistor and the capacitance value of said second capacitor, said oscillator means also including a C-MOS
integrated circuit;
means connected across said first capacitor for generating a constant voltage, said constant voltage generating means including a series connection of a diode-connected junction-type field effect transistor and a zener diode, said C-MOS integrated circuit being operated by said constant voltage generated across said zener diode;
means for counting said plurality of pulse signals and for producing a first signal upon counting said pulse signals up to a number corresponding to said predetermined delay time; and means responsive to said first signal for supplying the electrical energy stored in said first capacitor to said ignition device.
2. An electronic delay detonator for driving an ignition device with a predetermined time delay by being supplied with electrical energy, comprising:
input terminal means for supplying the electrical energy to said delay detonator;
a first capacitor for storing said electrical energy;
means inserted between said input terminal means and said first capacitor for preventing said stored electrical energy from being released through said input terminal means;
oscillator means electrically connected to said first capacitor and including a resistor and a second capacitor, for producing a plurality of pulse signals of a period proportional to the product of the resistance value of said resistor and the capacitance value of said second capacitor, said oscillator means also including a COOS
integrated circuit;
means connected between said first capacitor and said oscillator means for stabilizing the operation of said oscillator means, said stabilizing means including a series connection of a diode-connected junction-type field effect transistor and a zener diode, said C-MOS integrated circuit being operated by a voltage generated across said zener diode;
means for counting said plurality of pulse signals and for producing a first signal upon counting said pulse signals up to a number corresponding to said predetermined delay time; and means responsive to said first signal for supplying the electrical energy stored in said first capacitor to said ignition device, said supplying means including a thyristor inserted between said first capacitor and said ignition device, said thyristor having a gate and a cathode, the gate being supplied with said first signal.
input terminal means for supplying the electrical energy to said delay detonator;
a first capacitor for storing said electrical energy;
means inserted between said input terminal means and said first capacitor for preventing said stored electrical energy from being released through said input terminal means;
oscillator means electrically connected to said first capacitor and including a resistor and a second capacitor, for producing a plurality of pulse signals of a period proportional to the product of the resistance value of said resistor and the capacitance value of said second capacitor, said oscillator means also including a COOS
integrated circuit;
means connected between said first capacitor and said oscillator means for stabilizing the operation of said oscillator means, said stabilizing means including a series connection of a diode-connected junction-type field effect transistor and a zener diode, said C-MOS integrated circuit being operated by a voltage generated across said zener diode;
means for counting said plurality of pulse signals and for producing a first signal upon counting said pulse signals up to a number corresponding to said predetermined delay time; and means responsive to said first signal for supplying the electrical energy stored in said first capacitor to said ignition device, said supplying means including a thyristor inserted between said first capacitor and said ignition device, said thyristor having a gate and a cathode, the gate being supplied with said first signal.
3. An electronic delay detonator according to claim 2, wherein said zener diode comprises a planar-type zener diode.
4. An electronic delay detonator according to claim 2, wherein the capacitance of said second capacitor lies in the range of substantially 100 to 1,000 pF.
5. An electronic delay detonator according to claim 2, further comprising à transistor and a third capacitor, said transistor having a base, a collector and an emitter, the collector and the emitter being connected to the gate and the cathode of said thyristor, respectively, one end of said third capacitor being connected to said first capacitor, and the other end of said third capacitor being connected to a base of said transistor.
6. An electronic delay-detonator according to claim 5, wherein the capacitance of said second capacitor lies in the range of substantially 100 to 1,000 pF.
7. An electronic delay detonator according to claim 1, wherein said zener diode comprises a planar-type zener diode.
8. An electronic delay detonator according to claim 1, wherein the capacitance of said second capacitor lies in the range of substantially 100 to 1,000 pF.
9. An electronic delay detonator according to claim 1, wherein said preventing means includes a plurality of diodes in bridge connection.
10. An electronic delay detonator according to claim 1, wherein said supply means includes a thyristor inserted between said first capacitor and said ignition device, the gate of said thyristor being supplied with said first signal.
11. An electronic delay detonator according to claim 10, further comprising a transistor and a third capacitor, the collector and emitter of said transistor being connected respectively to the gate and cathode of said thyristor, one end of said third capacitor being connected to said first capacitor, and the other end of said third capacitor being connected to the base of said transistor.
12. An electronic delay detonator according to claim 1, wherein the capacitance of said second capacitor lies in the range of substantially 100 to 1,000 pF.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000452394A CA1226044A (en) | 1984-04-19 | 1984-04-19 | Electronic delay detonator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000452394A CA1226044A (en) | 1984-04-19 | 1984-04-19 | Electronic delay detonator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1226044A true CA1226044A (en) | 1987-08-25 |
Family
ID=4127695
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000452394A Expired CA1226044A (en) | 1984-04-19 | 1984-04-19 | Electronic delay detonator |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1226044A (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 |
-
1984
- 1984-04-19 CA CA000452394A patent/CA1226044A/en not_active Expired
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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