U.S. patent number 3,780,654 [Application Number 05/297,985] was granted by the patent office on 1973-12-25 for remote detonation system.
This patent grant is currently assigned to OKI Electric Industry Co., Ltd., Taisei Corporation. Invention is credited to Kenji Nakao, Masaaki Oguri, Masakatu Ohgaki, Ryozi Shimizu.
United States Patent |
3,780,654 |
Shimizu , et al. |
December 25, 1973 |
REMOTE DETONATION SYSTEM
Abstract
In a remote detonation system wherein a plurality of underwater
explosives are detonated simultaneously by command signals sent
from a remote control station, there are provided a control station
including an oscillator for generating a plurality of frequency
modulated waves and a sound wave transmitter for transmitting the
frequency modulated waves through the water as frequency modulated
command signals; a plurality of detonation control elements, each
including a sound wave receiver for receiving the frequency
modulated command signals from the control station, means for
demodulating the output from the sound wave receiver for
reproducing the frequency modulated command signals and ignition
means including a plurality of switches which are operated
sequentially by the output of the demodulating means; a plurality
of electric detonators each connected to the ignition means of the
detonation control elements, and a plurality of underwater
explosives detonated by the detonations of respective electric
detonators.
Inventors: |
Shimizu; Ryozi (Chigasaki,
JA), Nakao; Kenji (Yokohama, JA), Oguri;
Masaaki (Tokyo, JA), Ohgaki; Masakatu (Hiratsuka,
JA) |
Assignee: |
OKI Electric Industry Co., Ltd.
(Tokyo, JA)
Taisei Corporation (Tokyo, JA)
|
Family
ID: |
13733356 |
Appl.
No.: |
05/297,985 |
Filed: |
October 16, 1972 |
Foreign Application Priority Data
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Oct 15, 1971 [JA] |
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46/80970 |
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Current U.S.
Class: |
102/312; 102/215;
367/133; 367/2; 367/191 |
Current CPC
Class: |
G08C
23/02 (20130101) |
Current International
Class: |
G08C
23/02 (20060101); G08C 23/00 (20060101); F42d
003/00 () |
Field of
Search: |
;102/10,16,18,19.2,22,23,70.2 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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772,413 |
|
Apr 1957 |
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GB |
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1,062,320 |
|
Jul 1959 |
|
DT |
|
Primary Examiner: Pendegrass; Verlin R.
Claims
What is claimed is:
1. A remote detonation system comprising a control station
including oscillator means for generating a plurality of frequency
modulated waves and a sound wave transmitter for transmitting said
frequency modulated waves through water as frequency modulated
command signals; one or a plurality of detonation control elements,
each including a sound wave receiver for receiving said frequency
modulated command signals from said control station, means for
demodulating the output from said sound wave receiver for
reproducing said frequency modulated command signals and ignition
means including a plurality of switches which are operated
sequentially by the output of said demodulating means; a plurality
of electric detonators each connected to said ignition means of
said detonation control element; and a plurality of underwater
explosives detonated by the detonations of respective electric
detonators.
2. A remote demodulation system comprising a control station
including oscillator means for producing a plurality of frequency
modulated waves and a sound wave transmitter for transmitting said
frequency modulated wave through water as frequency modulated
command signals; a main detonation control element including a
first sound wave receiver for receiving said frequency modulated
command signals from said control station, means for demodulating
the output from said sound wave receiver for reproducing said
frequency modulated command signals, and ignition means including a
plurality of switches which are operated sequentially by the output
of said demodulating means; an electric detonator connected to said
ignition means of said main detonation control element; a
underwater main explosive detonated by the detonation of said
electric detonator; a second sound wave receiver for receiving said
frequency modulated command signals from said control station and
the percussion wave generated by the detonation of said main
explosive; a plurality of auxiliary detonation control elements,
each including means for selectively demodulating the output from
said second sound wave receiver for reproducing only a
predetermined one of said frequency modulated command signals,
level setting means connected to said second sound wave receiver
for detecting and transforming the received percussion wave into an
electric signal, and ignition means including switch means operated
by the outputs of said demodulating means and said level setting
means; a plurality of auxiliary electric detonators each connected
to said ignition means of said auxiliary detonation control
element; and a plurality of underwater auxiliary explosives each
detonated by the detonation of said auxiliary electric
detonator.
3. The remote detonation system according to claim 1 wherein said
oscillation means of said control station comprises a carrier wave
oscillator, a plurality of modulation signal generators, a
frequency modulator connected to said carrier wave oscillator, a
timing gate circuit for sequentially applying the outputs of said
plurality of modulation signal generators; and a power amplifier to
amplify the output from said frequency modulator for supplying the
amplified output to said sound wave transmitter.
4. The remote detonation system according to claim 2 wherein said
oscillation means of said control station comprises a carrier wave
oscillator, a plurality of modulation signal generators, a
frequency modulator connected to said carrier wave oscillator, a
timing gate circuit for sequentially applying the outputs of said
plurality of modulation signal generators; and a power amplifier to
amplify the output from said frequency modulator for supplying the
amplified output to said sound wave transmitter.
5. The remote detonation system according to claim 2 wherein the
demodulating means of said main detonation control element
comprises means for detecting a plurality of simultaneously
received frequency modulated command signals and timing means for
arranging in parallel the outputs of said detecting means.
6. The remote detonation system according to claim 2 wherein said
auxiliary explosives controlled by said auxiliary detonation
control elements are located at the bottom of water.
7. The remote detonation system according to claim 1 wherein two
types of said frequency modulated command signals are used.
8. The remote detonation system according to claim 2 wherein two
types of said frequency modulated command signals are used.
9. The remote detonation system according to claim 3 wherein the
demodulating means of said main detonation control element
comprises an amplifier for amplifying the output of said sound wave
receiver, a limiter for limiting the amplitude of the output of
said amplifier, a demodulator for demodulating the frequency
modulated output of said limiter, a plurality of bandpass filters
for filtering respective command signals out of the output from
said demodulator, and a rectifying and integrating circuit to
rectify and integrate the outputs from said bandpass filters for
operating said switches of said ignition means.
10. The remote detonation system according to claim 8 wherein said
timing circuit comprises a first rectifying and integrating circuit
responsive to the detected output of a first command signal, a
first Schmit circuit triggered by the output from said first
rectifying and integrating circuit, a first monostable
multivibrator triggered by the output from said first Schmit
circuit, a second monostable multivibrator triggered by the output
from said first monostable multivibrator, a second rectifying and
integrating circuit response to the detected output of a second
command signal, a second Schmit circuit triggered by the output
from said second rectifying and integrating circuit, an AND gate
circuit connected to receive at its inputs the output from said
second monostable multivibrator and the output from said second
Schmit circuit, means responsive to the output of said first
monostable multivibrator for actuating a first switch of said
ignition means, and means responsive to the output from said AND
gate circuit for actuating a second switch of said ignition
means.
11. The remote detonation system according to claim 8 wherein said
ignition means comprises a source of supply, a series circuit
including a first silicon controlled rectifier element and a load
resistor, said series circuit being connected across said source, a
first input terminal connected to the gate electrode of said first
silicon controlled rectifier element for receiving a first input
signal, a second series circuit including a charging resistor and a
capacitor, said second series circuit being connected across the
cathode electrode of said first silicon controlled rectifier
element and the negative pole of said source, a second silicon
controlled rectifier element with its anode electrode connected to
the juncture between said charging resistor and said capacitor,
means to connect an electric detonator across the cathode electrode
of said second silicon controlled rectifier element and the
negative pole of said source, and a second input terminal connected
to the gate electrode of said second silicon controlled rectifier
element for receiving a second input signal.
Description
BACKGROUND OF THE INVENTION
This invention relates to a remote detonation system, more
particularly a novel system for simultaneously detonating a
pluraltiy of explosives loaded in a underwater rock by using a
frequency modulated signal transmitted from a remote control
station.
Heretobefore, in order to explode an underwater rock with
explosives by a signal transmitted from a remote control station it
has been the practice to drill a plurality openings through the
rock, charge explosives provided with electric detonators in
respective openings, electrically connect the detonators in series
or parallel, and connect the detonators to a control switch located
in the remote control station through an electric cable whereby the
plurality of explosives are detonated simultaneously. Such a
system, however, requires to use a submergible cable and to connect
it with respective electric detonators in water. For this reason,
there are such disadvantages that the cable is broken by a tidal
current, that the electrical connections between the cable and the
electric detonators are damaged and that the cable becomes tangled.
Thus, the working efficiency is low so that it has been impossible
to use such a system in deep water.
To eliminate the use of an electric cable it has been proposed to
use ultrasonic waves. However, ultrasonic receivers associated with
the detonators often respond to underwater noises thus there is
probability of causing unexpected detonations resulting in
disasters. Furthermore, where it is necessary to detonate a large
underwater ground area by using a large number of explosives it has
been difficult to simultaneously detonate them due to the
difference in times of the arrival of the supersonic waves to
respective detonators, thereby decreasing the efficiency of
detonation.
SUMMARY OF THE INVENTION
Accordingly, it is an object of this invention to provide a new and
improved remote induction detonation system using ultrasonic wave
and capable of safely and accurately detonate a detonator without
the fear of any miss-detonation caused by miss-connection or
breakage of a cable and which is not required to use any underwater
cable or electrical conductor which should be connected to the
detonator under water.
Another object of this invention is to provide a novel remote
induction detonation system using ultrasonic wave which can safely
and simultaneously detonate a plurality of detonators from a remote
point without being interferred by underwater noises even in
applications where the conventional system using an electrical
cable is not practical due to a rapid tidal current or a large
depth.
A further object of this ivnention is to provide a novel remote
induction detonation system utilizing ultrasonic wave wherein a
main detonator is firstly detonated by a command signal transmitted
from a remote control station and then a plurality of auxiliary
detonators are detonated simultaneously by the cooperation of said
command signal and the percussion wave generated by the explosion
of the main detonator.
Still further object of this invention is to provide a novel
detonation control circuit or element which accurately responds
only to the detonation command signal for electrically detonating
the detonator.
According to this invention there is provided a remote detonation
system wherein a plurality of underwater explosives are detonated
simultaneously by command signals sent from a remote control
station, characterized in that there are provided a control station
including an oscillator for generating a plurality of frequency
modulated waves and a sound wave transmitter for transmitting the
frequency modulated waves through the water as frequency modulated
command signals; a plurality of detonation control elements, each
including a sound wave receiver for receiving the frequency
modulated command signals from the control station, means for
demodulating the output from the sound wave receiver for
reproducing the frequency modulated command signals and ignition
means including a plurality of switches which are operated
sequentially by the output of the demodulating means; a plurality
of electric detonators each connected to the ignition means of the
detonation control element; and a plurality of underwater
explosives detonated by the detonations of respective electric
detonators.
BRIEF DESCRIPTION OF THE DRAWINGS
Further objects and advantages will become apparent from the
following detailed description taken in conjunction with the
accompanying drawings in which:
FIGS. 1 and 2 are diagrams to show basic arrangements of slightly
different remote detonation systems embodying the invention wherein
in the arrangment shown in FIG. 1 both the main detonator and a
pluraltiy of auxiliary detonators are installed at a substantially
equal underwater level whereas in the arrangement shown in FIG. 2
the main detonator is located at a higher underwater level.
FIG. 3 shows a block diagram of one example of a control station
used in this invention;
FIG. 4 shows a block diagram of a detonation control circuit
associated with the main detonator;
FIG. 5 shows a block diagram of a detonation control circuit for
the auxiliary detonators;
FIG. 6 shows connection diagram of a ignition circuit for igniting
a detonator;
FIG. 7 shows a block diagram of one example of the timing circuit
used in the control station used in this invention;
FIG. 8 shows a block diagram of one example of a timing circuit
utilized in a detonator of this invention and
FIG. 9 shows waveforms of various circuit elements utilized in the
timing circuit shown in FIG. 8.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The remote detonation system shown in FIG. 1 comprises a control
station 1 for transmitting a pluraltiy of frequency modulated
command signals through a ultrasonic sound transmitter 2 immersed
in water, a main detonation control element 4 located at the bottom
of the water and provided with a sound wave receiver 3 for
receiving the frequency modulated command signals transmitted from
transmitter 2. An electric detonator 5 is included in the
detonation control element 4 for detonating an explosive 6. There
are also provided a plurality of sound wave receivers 8.sub.1,
8.sub.2 . . . 8.sub.n arranged to receive the frequency modulated
command signals transmitted from the transmitter 2 and the
percussion wave generated by the detonation of the main explosive 6
for actuating detonation control elements 9.sub.1, 9.sub.2, . . .
9.sub.n respectively which are connected to electric detonators
9.sub.1, 9.sub.2, . . . 9.sub.n associated with auxiliary
explosives 11.sub.1, 11.sub.2, . . . 11.sub.n loaded in the holes
on the rock at the bottom of the water.
A plurality of frequency modulated command signals radiated by
ultrasonic wave transmitter 2 of the control station 1 propergate
through the water to be received by the wave receiver 3 of the main
detonation control element 4 and a plurality of wave receivers
8.sub.1, 8.sub.2, . . . 8.sub.n of the auxiliary detonation control
elements 9.sub.1, 9.sub.2, . . . 9.sub.n. The main detonation
control element 4 located at the bottom of the water operates to
sequentially demodulate and detect a series of the frequency
modulated command signals which are received by wave receiver 3 for
detonating electric detonator 5 and explosive 6 by the output of
the main detonation control element 4. On the other hand, wave
receivers 8.sub.1, 8.sub.2, . . . 8.sub.n of the auxiliary
detonation control elements 9.sub.1, 9.sub.2, . . . 9.sub.n operate
to receive predetermined signals among a series of the frequency
modulated command signals and an intense percussion wave generated
by the explosive of the main explosive 6, thereby energizing
respective electric detonators 10.sub.1, 10.sub.2, . . . 10.sub.n
by their outputs in response to the predetermined signals and the
percussion wave for simultaneously detonating auxiliary explosives
11, 12, . . . 11.sub.n.
In the modified embodiment shown in FIG. 2, the detonation control
element 4 is floated on the surface of the water, and wave receiver
3, and a detonator 5 associated with the main explosive 6 are
suspended from and electrically connected to the detonation control
element 4. The levels of the wave receiver 3, the detonator 5 and
the main explosive 6 may be relatively shallow.
As above described, the control station 1 utilized in this
invention is designed to generate a plurality of frequency
modulated command signals but for the sake of brevity it is herein
assumed that the control station generates two such signals. In the
embodiment shown in FIG. 3, there is provided a carrier wave
oscillator 12 for supplying a carrier wave of frequency f.sub.0
(for example 20 KHz) to a frequency modulator 16. There are also
provided modulation signal oscillators 13 and 14 for generating
modulation signals of frequencies f.sub.1 (for example 500 Hz) and
f.sub.2 (for example 400 Hz). The modulation signal f.sub.1 from
the modulation signal oscillator 13 is supplied to the frequency
modulator 16 for a predetermined interval through a timing gate
circuit 15, whereas the modulation signal f.sub.2 from the
modulation signal oscillator 13 is supplied to the frequency
modulator 16 for another predetermined interval also through the
timing gate circuit 15. As a result, the output from the frequency
modulator 16 comprises, a command signal produced by frequency
modulating the carrier wave f.sub.0 with signal f.sub.1 followed by
a command signal produced by frequency modulating the carrier wave
f.sub.0 with signal f.sub.2. These two frequency modulated command
signals are amplified by a power amplifier 17 and then radiated
into the water through the ultrasonic wave transmitter 2. The
ultrasonic waves are received by the main and auxiliary wave
receivers 3 and 8.sub.1, 8.sub.2, . . . 8.sub.n.
Referring now to FIG. 4, the two frequency modulated command
signals received by the receiver 3 of the main explosive 6 are
amplified by an amplifier 18 and their amplitudes are limited to a
constant level by a limiter 19. The outputs of the limiter are
demodulated by a demodulator 20 and are then separated into two
command signals f.sub.1 and f.sub.2 by bandpass filters f.sub.1 and
f.sub.2 having narrow passbands. After being amplified by an
ampifier 23, the signal f.sub.1 is rectified by a rectifying and
integrating circuit 24 to cloe a first switch 25 of the ignition
circuit 25. Although the detail of this switch will be described
later, it is constructed such that it is maintained in the closed
condition for a predetermined interval once it has been closed. On
the other hand, the command signal f.sub.2 from the bandpass filter
22 appears later than the output signal f.sub.1 from the bandpass
filter f.sub.1 and the signal f.sub.2 is used to close a second
switch 28 through an amplifier 26 and a rectifying and integrating
circuit 27. When first and second switches 25 and 26 are closed in
this manner, an ignition circuit that can be traced from a source
of supply 29 to the ground via first and second switches 25 and 28
and the electric detonator 5 is closed to detonate the detonator 5
and hence the main explosive 6.
As shown in FIG. 5, in a detonation control element, the frequency
modulated command signals received by a wave receiver 8 are
amplified by an amplifier 30 and the amplitudes of the signals are
limited to a definite level by the operation of a limiter 31. The
outputs from limiter 31 are demodulated by a demodulator 32 and are
then supplied to a bandpass filter 33. As above described, since
the auxiliary detonation control element is designed to detect only
a predetermined signal among a number of frequency modulated
command signals received by the receiver 8, the bandpass filter 33
is designed to pass only the command signal having frequency
f.sub.1. Accordingly, the filter 33 produces an output only when
the command signal is modulated by frequency f.sub.1. The output
from the demodulator 33 closes a first switch 36 via an amplifier
34 and a rectifier 35. Under these conditions, as has been
described herein above, since the main explosive 6 has already been
detonated, an intense percussion wave generated thereby is received
by the wave receiver 8 and a signal from this receiver is
transformed into a high voltage pulse wave having a steep wavefront
by means of a limiter 38 and this pulse wave exceeds the
predetermined level to close a second switch 39 in the ignition
circuit. As a result, current flows through an electric detonator
10 from a source 37 via first and second switches 36 and 39 thus
detonating simultaneously the auxiliary explosives. Since the
limitor 38 may comprise a well known combination of a resistor, a
constant voltage diode and a diode, its detail will not be
described.
FIG. 6 illustrates one example of an ignition circuit utlized in
the main and auxiliary detonation control elements shown in FIGS. 4
and 5. The ignition circuit shown in FIG. 5 comprises a source 41
which corresponds to the source 29 or 37 shown in FIG. 4 or FIG. 5.
A series circuit including a first silicon controlled rectifier
element 42 and a load resistor 43 is connected across the source
41. The gate electrode of the silicon controlled rectifier element
42 is connected to the negative pole of source 41 via a stabilizing
resistor 44 and to a terminal 46 which receives the demodulated
command signal f.sub.1 through a diode 45 connected to pass current
only in the forward direction, whereas the cathode electrode of the
rectifier element 42 is connected to the negative pole of the
source 41 through a charging resistor 48 and a capacitor 44 which
are connected in series. There is also provided a second silicon
controlled rectifier element 49 with its anode electrode connected
to the juncture between resistor 47 and capacitor 48. The cathode
electrode of the silicon controlled rectifier element 49 is
connected to the negative pole of the source 41 through a load
resistor 50 to the same negative pole through an electric detonator
51 (corresponding to the detonator 5 or 10 shown in FIG. 4 or FIG.
5). The gate electrode of the rectifier element 49 is connected to
an input terminal 53 through a diode 52, the input terminal 53
being connected to receive the second command signal (that is the
command signal f.sub.2 in the main detonation control element shown
in FIG. 4 or the output from limiter 38 in the auxiliary detonation
control element shown in FIG. 5). A resistor 54 is connected
between the gate electrode of the second silicon controlled
rectifier element 49 and the negative pole of source 41 for the
purpose of stabilizing the operation of the gate electrode.
In operation, the positive voltage of the first command signal
impressed across the input terminals 44 and 46' is applied to the
gate electrode of the first silicon controlled rectifier element 42
through diode 45 thus turning ON the rectifier element 42. When
turned ON the silicon controlled rectifier element 42 charges a
capacitor 48 of a relatively large capacity through the charging
resistor 47. When the second command signal is impressed across
input terminals 53 and 53', after the capacitor 48 has been
completely charged up, this command signal is applied to the gate
electrode of the second silicon controlled rectifier element 49
through diode 52 thus turning ON this rectifier element 49.
Conduction of the rectifier element 49 discharges capacitor 48
through electric detonator 51 thus detonating the same. It is to be
understood that the resistance value of the load resistor 50 of the
silicon controlled rectifier element 49 is made sufficiently larger
than that of the electric detonator 51 thus ensuring a large
current to flow through the detonator 51.
As above described, the circuit shown in FIG. 6 operates to turn ON
the first silicon controlled rectifier element 42 for charging the
capacitor 48 when it receives the first command signal and to
detonate the electric detonator when it receives the second command
signal after completion of the charging of the capacitor.
Accordingly, the electric detonator is detonated only when the
first and second command signals arrive consecutively or serially.
In other words, the detonator will not be operated when the two
command signals are received at the same time or in the opposite
order. When connecting the ignition circuit with the electric
detonator in the field, that is when connecting the detonator
across terminals 55 and 56, even when the silicon controlled
rectifier elements 42 and 49 are inadvertently turned ON, it is
possible to limit the current flowing through the detonator to a
small value not to ignit the same because the resistance value of
the charging resistor 47 is set to a high value.
FIG. 7 is a connection diagram showing a detailed connection of the
timing gate circuit 15 shown in FIG. 3. As shown, the timing gate
circuit 15 comprises a detonation command switch CS, a reset switch
RS, timers T.sub.1 and T.sub.2, relay coils RL-1, RL-2, RL-3 and
RL-4 and relay contacts operated thereby. When the detonation
command switch CS is closed, relay coil CL-1 is energized which is
maintained in the energized condition by a self-holding contact
r1-1. Energization of relay coil RL-1 energizes relay coil RL-2
through a contact of timer T.sub.1. As a result, contact r1-2 of
relay coil LR-2 is closed to apply the signal f.sub.1 generated by
the modulation signal oscillator 13 to the frequency modulator 16.
Concurrently therewith relay coil RL-3 is energized by relay
contact r1-2a and is self-held by its self-holding contact r1-3.
When relay coil RL-2 is energized, one of its contact, not shown,
disconnects the timer T.sub.1 from source -24V, but the timer
T.sub.1 continues to operate for a preset interval. Upon
termination of this preset interval, relay coil RL-2 is deenergized
to open its contact r1-2, thus interrupting the supply of the
signal f.sub.1 to modulator 16. Concurrently therewith, relay coil
RL-4 is energized through contacts r1-3, r1-21 and the contact of
timer T.sub.2. Accordingly, the output f.sub.2 from modulation
signal oscillator 14 will be applied to frequency modulator 16 via
contact r1-4. The supply of output f.sub.2 to the frequency
modulator 16 is terminated when the interval set in timer T.sub.2
has elapsed. In this manner, by using the timing gate circuit it is
possible to send out sequentially two types of command signals from
a single wave transmitter 2.
FIGS. 3 and 7 illustrate an embodiment of this invention wherein a
plurality of command signals are transmitted sequentially from a
control station and these serial command signal waves are received
by remote detonation control elements. However, it should be
understood that the same object can be accomplished by
simultaneously transmitting a plurality of command signals from the
control office, receiving these command signal waves at the remote
detonation control elements, transforming these simultaneously
received control signal waves into trains of serial signals, and
supplying the trains to respective ignition circuits. In such a
modification, it is not necessary to use the timing gate circuit
shown in FIG. 3 and the circuit between the bandpass filters 21 and
22 and switches 25 and 28 of the detonation control element shown
in FIG. 4 may be replaced by the timing circuit shown in FIG. 8.
More particularly, as shown in FIG. 8, the output from the bandpass
filter 21 is supplied to a rectifying and integrating circuit 57
and the output thereof is coupled to a Schmit circuit 59. The
output from the Schmit circuit 59 is applied to serially connected
monostable multivibrators 61 and 62. On the other hand, the output
from the bandpass filter 22 is applied to a Schmit circuit 60
through a rectifying and integrating circuit 58. The output from
monostable multivibrator 61 is supplied to a terminal 63 leading to
the first switch 25 of the ignition circuit shown in FIG. 4,
whereas the outputs from Schmit circuit 60 and monostable
multivibrator 62 are coupled to a terminal 65 leading to the second
switch 28 via an AND gate circuit 64.
In the arrangement shown in FIG. 8, since first and second control
signals f.sub.1 and f.sub.2 arrive at the inputs and bandpass
filters 21 and 22 at the same time, the inputs to these filters re
shown by waveforms A and B, respectively, of FIG. 9. These
waveforms are transformed into waveforms C and D by the action of
the rectifying and integrating circuits 57 and 58. Schmit circuits
59 and 60 are triggered respectively by the outputs of the
rectifying and integrating circuits 57 and 58 to produce waves as
shown by FIG. 9E. The output from Schmit circuit 59 triggers the
monostable multivibrator 61 for supplying to the monostable
multivibrator 62 and terminal 63 a pulse, FIG. 9F, having a pulse
width determined by the time constant of the monostable
multivibrator 61. The output supplied to terminal 63 is used to
operate the first switch 25. The output from the monostable
multivibrator 62 is shown by FIG. 9G and is supplied to AND gate 64
together with the output, FIG. 9E, of Schmid circuit 60 so that an
output, FIG. 9H, corresponding to the logical product of these two
signals is applied to terminal 65 for operating the second switch
28. As above described, by using the timing circuit shown in FIG.
8, it is possible to convert plurality of command signals which are
received simultaneously into sequential or series command signals
for sequentially closing the switches of discrete ignition
circuits.
In the embodiment of the auxiliary detonation control element shown
in FIG. 5, instead of using circuit elements 30 through 35 which
are used for processing the signals for actuating the first switch
36 by detecting a prescribed command signal it is also possible to
use a well known mechanical or electrical timer which is
constructed to operate for a predetermined interval for closing the
first switch 36 and maintaining the same in the closed condition,
the predetermined interval corresponding to the interval in which
the detonation command signal is transmitted from the control
station.
Various types of the processing circuit may be substituted for the
processing circuit including various circuit elements starting from
the bandpass filter to the switches shown in FIGS. 4 and 5. Thus
for example, it is also possible to apply the output from the
bandpass filter to a differentiating circuit for driving the
monostable multivibrator with the differentiated signal. The output
of the monostable multivibrator is then integrated for operating
the switch with the output of the integrator. Alternatively, the
output from the bandpass filter may be applied to a slicer for
driving a flip-flop circuit with the sliced output from the slicer.
The output of the flip-flop circuit is integrated for operating the
switch with output from the integrator.
Although in the embodiments shown in FIGS. 4 and 5 the main and
auxiliary detonation control elements are used for inducing the
detonation of the auxiliary explosives by the percussion wave
generated by the detonation of the main explosive, it will be clear
that the invention is by no means limited to these particular
embodiments and that instead of using auxiliary detonation control
elements, it is also possible to use a plurality of main detonation
control elements, each constructed as shown in FIG. 4.
Further, although in the foregoing embodiments, two types of the
frequency modulated command signals were used it is also possible
to use three or more types of the frequency modulated command
signals from the standpoint of safety. In such a case, it is
necessary to use switches in the ignition circuit of the same
number as that of the frequency modulated command signals.
* * * * *