U.S. patent number 3,650,174 [Application Number 05/002,274] was granted by the patent office on 1972-03-21 for electronic ignition system for firearms.
Invention is credited to Thomas Sloan Nelsen.
United States Patent |
3,650,174 |
Nelsen |
March 21, 1972 |
ELECTRONIC IGNITION SYSTEM FOR FIREARMS
Abstract
An electronic ignition system for firing electrically primed
ammunition in a firearm. The system includes a trigger for
converting mechanical movement to electrical signals without the
need of electrical contacts, and logic circuitry which permits
selective firing of multiple barrels with a single trigger. Various
electrical and mechanical safety features, including retractable
firing pins, are provided to prevent accidental discharge of the
weapon.
Inventors: |
Nelsen; Thomas Sloan (Sanford,
CA) |
Family
ID: |
21700017 |
Appl.
No.: |
05/002,274 |
Filed: |
January 12, 1970 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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820932 |
May 1, 1969 |
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Current U.S.
Class: |
89/28.05;
42/42.01; 42/84; 89/127 |
Current CPC
Class: |
F41A
19/58 (20130101) |
Current International
Class: |
F41A
19/00 (20060101); F41A 19/58 (20060101); F41c
019/12 (); F41f 013/08 () |
Field of
Search: |
;42/42,84
;89/28,127,135 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Borchelt; Benjamin A.
Assistant Examiner: Bentley; Stephen C.
Claims
What is claimed is:
1. In an electronic ignition system for selectively firing
electrically primed ammunition in different barrels of a firearm
having a single trigger, means operably connected to the trigger
for producing an electrical trigger signal each time said trigger
is pulled by a shooter, electrically conductive firing pins for
contacting the primer heads of electrically primed ammunition
disposed for being fired through the barrels of the firearm, one
such firing pin being provided for each barrel, a source of
electrical energy, and electronic means connected to said firing
pins and to said source for energizing a different one of said
firing pins in response to alternate trigger signals.
2. An electronic ignition system as in claim 1 wherein said
electronic means includes an electronic firing circuit connected to
each of said firing pins and electronic logic control means
intermediate the means for producing the trigger signals and the
firing circuits for actuating a different one of said firing
circuits in response to alternate trigger signals.
3. An electronic ignition system as in claim 2 wherein said logic
control means includes a one-shot multivibrator having first and
second states and a time constant such that said multivibrator
remains in its second state for a predetermined period of time
shorter than the interval between an intentional pull of the
trigger by the shooter and the reflexive trigger pull which
normally follows a discharge of the firearm, said multivibrator
being connected in such manner that it switches to its second state
in response to each trigger signal then returns to its first state
after said predetermined period of time, one transition of said
multivibrator back to its first state serving to inhibit actuation
of said firing circuits in response to the next successive trigger
signal, and the next such transition serving to enable one of said
firing circuits to respond to the next trigger signal following
said transition.
4. An electronic ignition system as in claim 2 wherein said logic
control means includes a one-shot multivibrator having first and
second states and a time constant such that said multivibrator
remains in its second state for a period of time longer than the
interval between an intentional pull of the trigger by the shooter
and the reflexive trigger pull which normally follows a discharge
of the firearm, said multivibrator being connected in such manner
that each trigger signal occurring while said multivibrator is in
its first state causes said multivibrator to switch to its second
state and inhibit actuation of said firing circuits as long as said
multivibrator remains in said second state.
5. An electronic ignition system as in claim 1 wherein the means
for producing an electrical trigger signal includes at least one
pressure sensitive resistive element disposed for detecting
movement of said trigger.
6. An electronic ignition system as in claim 1 wherein the means
for producing an electrical trigger signal includes a flexible
member disposed for being flexed when the trigger is pulled and an
electrical resistance strain gage mounted on one surface of said
flexible member, said strain gage being connected electrically in
one arm of a bridge circuit.
7. An electronic ignition system as in claim 1 wherein the means
for producing an electrical trigger signal includes a pressure
sensitive switch having no exposed contacts.
8. An electronic ignition system as in claim 7 wherein said
pressure sensitive switch is a pressure sensitive silicon
controlled rectifier.
9. In an electronic ignition system for firing electrically primed
ammunition through the barrel of a firearm, an electrically
conductive firing pin disposed for contacting the primer head of
electrically primed ammunition disposed for being fired through the
barrel, a source of electrical energy, a trigger adapted being
pulled by a shooter's trigger finger, and a pressure sensitive
solid state switching device disposed for changing its state of
conductivity in response to a pull of the trigger, said device
being connected for controlling the flow of energy from said source
to said firing pin in such manner that said firing pin is energized
in response to a pull of the trigger by the shooter.
10. An electronic ignition system as in claim 9 wherein said
switching device is a pressure sensitive silicon controlled
rectifier.
11. In a method for constructing an electronic ignition system for
firing an electrically primed cartridge in a firearm, the steps of
providing an electrical firing pin for contacting the primer head
of the cartridge, connecting a pressure sensitive solid-state
switching device to said firing pin and to a source of electrical
energy, said switching device being adapted for changing its state
of conductivity in response to pressure applied thereto, and
mounting said switching device in proximity to the trigger of the
firearm so that actuation of said trigger causes a pressure to be
applied to said device, thereby changing the state of conductivity
of said device and energizing said firing pin.
Description
BACKGROUND OF THE INVENTION
This invention pertains generally to firearms and more particularly
to an electronic system for firing electrically primed
ammunition.
In conventional firearms, a mechanical striker including a hammer
and firing pin is provided for detonating percussion primers. A
time lag, known as lock time, between trigger pull and ignition of
the ammunition is inherent in this type of firing mechanism. The
delay is caused by the mechanical inertia of the hammer and firing
pin and typically varies from several milliseconds to tens of
milliseconds. Mechanical systems are also subject to wear, with
consequent deterioration of performance.
Weapons heretofore provided for firing ammunition by electrical
means have included electrical contacts, piezo-electric crystals,
and/or means for electrically releasing a mechanical striker. These
systems all have drawbacks, such as the unreliability of electrical
switches and a time delay in the firing mechanism. Furthermore,
such systems generally require a separate trigger for each barrel
of the weapon.
There is, therefore, a need for a new and improved ignition system
for firearms which overcomes the foregoing and other problems
encountered with firing systems heretofore provided.
SUMMARY AND OBJECTS OF THE INVENTION
The present invention provides an electronic ignition system for
firearms which has no mechanical contacts in its firing circuit.
The system substantially eliminates the time delay of the firing
mechanism, or lock time, and permits multibarrel operation from a
single trigger without double ignition and without deterioration of
performance with use. This system utilizes semiconductor devices
and can be powered by small batteries which are easily carried by
the firearm.
It is in general an object of the present invention to provide a
new and improved electronic ignition system for firing electrically
primed ammunition in a firearm.
Another object of the invention is to provide an ignition system of
the above character having no mechanical electrical contacts in its
firing control circuit.
Another object of the invention is to provide an ignition system of
the above character which includes means for preventing accidental
discharge of the firearm.
Another object of the invention is to provide an ignition system of
the above character wherein a single trigger selectively controls
the firing multiple barrels.
Another object of the invention is to provide an ignition system of
the above character which includes electronic means for controlling
the firing order of multi-barrel weapons.
Another object of the invention is to provide an ignition system of
the above character which includes means for preventing multiple
simultaneous ignition of the ammunition in different barrels of the
weapon.
Another object of the invention is to provide an ignition system of
the above character wherein the pull and travel of the trigger can
be adjusted over wide ranges without danger of accidental discharge
of the weapon when they are adjusted to low values.
Another object of the invention is to provide an ignition system of
the above character wherein the firing pins are retracted at all
times except when the breech is closed and locked to prevent
accidental discharge of the ammunition in a partially open
weapon.
Additional objects and features of the invention will be apparent
from the following description in which the preferred embodiments
are set forth in detail in conjunction with the accompanying
drawing.
BRIEF DESCRIPTION OF THE DRAWing
FIG. 1 is a block diagram of one embodiment of an electronic
ignition system incorporating the present invention.
FIG. 2 is a cross-sectional view of the firing chamber of a
two-barrel over-under type firing arm having retractable firing
pins incorporating the present invention.
FIG. 3 is a elevational view of one embodiment of a trigger
incorporating the present invention.
FIG. 4 is a circuit diagram of the trigger circuit which is
particularly suitable for use with the trigger embodiment shown in
FIG. 3.
FIG. 5 is an elevational view of a second embodiment of a trigger
incorporating the present invention.
FIG. 6 is a circuit diagram of a trigger circuit which is
particularly suitable for use with the trigger embodiment shown in
FIG. 5.
FIG. 7 is a circuit diagram of one embodiment of a control circuit
incorporating the present invention.
FIG. 8 is a circuit diagram of another embodiment of a control
circuit incorporating the present invention.
FIG. 9 is a circuit diagram of one embodiment of a firing circuit
incorporating the present invention.
FIG. 10 is an elevational view of one embodiment of the trigger
utilizing a pressure-sensitive silicon controlled rectifier and
incorporating the present invention.
FIG. 11 is a schematic diagram of a combined trigger circuit and
firing circuit which is particularly suitable for use with the
trigger embodiment shown in FIG. 10.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the preferred embodiment of the electronic ignition system
illustrated in FIG. 1, a single trigger controls the firing of two
separate barrels. This system includes generally trigger means 11,
a control circuit 12, a firing sequence selector 13, a first firing
circuit 14 and firing pin and cartridge 15 associated with one
barrel of the gun, and a second firing circuit 16 and a firing pin
and cartridge 17 associated with the second barrel. Power is
supplied to the trigger means 11, control circuit 12, and firing
sequence selector 13 by means of a first power supply 21, and to
the firing circuits 14 and 16 by a second power supply 22. A safety
switch 23 is connected between the power supply 22 and the firing
circuits to provide means for removing the power from the firing
circuits to prevent accidental discharge of the gun. This switch
can also be used to conserve power when the gun is not in use.
Similarly, an on-off switch 24 is provided between the power supply
21 and the circuits which it supplies.
FIG. 2 illustrates firing pins embodying the present invention in
an over-under type of double-barrel weapon. One firing pin 26 is
provided for each of the two barrels which are designated upper
barrel 27 and lower barrel 28. The pins 26 are fabricated of an
electrically conductive material. Each pin is an elongate member of
substantially circular cross section, with a radially extending
flange portion 29 intermediate its two ends. One end 31 of each pin
is adapted for contacting the primer head of a electrically primed
cartridge in a manner hereinafter described in detail. The other
end 32 of each of the pins is connected to one of the firing
circuits by means of an insulated wire 33. The pins are otherwise
insulated from electrical contact by means of insulating sleeves
34.
The firing pins 26 and their insulating sleeves 34 are slidably
mounted in bore holes 36 formed in the frame 37 of the firearm.
Each of the bore holes includes an inner bore 36a and a large outer
bore 36b. An annular shoulder 36c is formed between the inner and
outer bores.
Means is provided for urging each of the firing pins 26 forward
into good electrical contact with the primer heads of cartridges in
the weapon when the breech is closed and locked. This means
includes an actuator block 38 and resilient spring members 39. The
block 38 is formed to include bore holes 38a in which the outer
ends of the firing pins 26 are slidably mounted. The springs 39 are
constrained between the actuator block 38 and the flange portions
29 of the firing pins. The actuator block is attached to the
locking bolt 41 of the firearm and adapted for movement forward and
rearward with it. Thus, when the bolt is moved forward into its
locking position, the springs 39 urge the firing pins 26 forward
into contact with the primer heads 42 of cartridges 43 in the
firing chamber. The cartridges also include an outer casing 44
having a metallic base portion 44a which is grounded electrically
to the weapon frame 37 by direct contact with the walls of the
firing chamber, and a charge of powder 46 in the casing 44.
The primer heads 42 include a metallic shell 42a press-fitted into
the base portion 44a of the cartridge casing, an electrical contact
42b mounted in the shell 42a and electrically insulated therefrom
by an insulator 42c, and a charge of priming compound 42d. The
firing pins 26 contact only the electrical contacts 42b of the
primer heads, and the priming compound 42d is ignited by the
passage of an electric current between the electrical contact and
the primer shell. Ignition of the priming compound causes ignition
of the powder charge 46.
Means is provided for retracting the firing pins 26 to prevent
accidental discharge of the weapon whenever the breech is unlocked
or open. This means includes resilient spring members 47 which are
constrained between the flange portions 29 of the firing pins and
the annular shoulders 36c of the firing pin bores 36. The springs
47 have a smaller spring constant than do the springs 39 so that
they will not prevent the firing pins from making good electrical
contact with the primer heads when the bolt is in its locked
position. When the bolt is unlocked and the tension in the springs
39 is relaxed, however, the spring members 47 urge the firing pins
26 back so they cannot make contact with the cartridges.
While the firing pins have been described with reference to an
over-under type of gun, the system of retractable insulated firing
pins actuated by the breech locking mechanism can be applied
equally well in side-by-side weapons, drillings, vierlings, and
single-barrel guns, including both single-shot weapons and
repeaters of the pump action and automatic types.
A preferred embodiment of a trigger mechanism for converting
mechanical movement into electrical signals without electrical
contacts is shown in FIG. 3. This mechanism includes a pivotally
mounted trigger 48 and a flexible arm 51, one end of which is
secured to the weapon frame 37. The trigger 48 includes a heel 48a
which engages the free end of the flexible arm 51. The arm 51 is
fabricated of a resilient material, such as spring steel, and
strain gages R-52 and R-53 are affixed to its upper and lower
surfaces, respectively. When the trigger 48 is pulled, the heel 48a
is moved upward, flexing the arm 51 and straining the strain gages
R-52 and R-53 in opposite directions.
As can be seen in FIG. 4, strain gages R-52 and R-53 are connected
as opposite arms in a conventional bridge circuit. The bridge
circuit also includes balancing resistors R-54 and R-56. Resistor
R-56 is a variable resistor which permits balancing of the bridge
when the trigger 48 is in its rest position. The output of the
bridge circuit is applied to the input terminals of a conventional
differential amplifier A-57 A through resistors R-58 and R-59. When
the trigger is in its rest position, the voltage at output terminal
61 of the differential amplifier A-57 is high. When the trigger is
pulled and the bridge is unbalanced, the voltage at output terminal
61 is low. A resistor R-62 is connected between the output terminal
61 and one of the input terminals of the differential amplifier.
This resistor provides hysteresis in the action of the differential
amplifier so that the transition from high to low output voltage
will be a sharp one.
Means is provided for adjusting the travel and pull of the trigger
48. The means for adjusting the travel includes an adjustable stop
63 and a fixed stop 64 adapted for engaging the lower and upper
surfaces, respectively, of the forward trigger arm 48b. As
illustrated, the adjustable stop 63 can be a screw threadably
mounted in the gun frame 37. The pull is determined primarily by a
resilient spring member 66 constrained between the forward trigger
arm 48b and the gun frame 37. In the rest position, this spring
urges the forward trigger arm into engagement with the fixed stop
64. This system permits the travel and pull of the trigger to be
adjusted to very small values without danger of accidental
discharge by jarring or dropping the gun. This safety is possible
because the spring arm 51 has a low mass and is not stressed when
the trigger is in its rest position.
The sensitivity of the trigger, or the threshold for firing is
based upon the difference in resistance between the two strain
gages. This sensitivity is primarily dependent upon the spring
constant of the flexible arm, the properties of the strain gages,
and the design of the circuit to which they are connected. Thus,
the sensitivity can be adjusted independently of the travel and
pull of the trigger.
An alternative trigger mechanism and trigger circuit is shown in
FIGS. 5 and 6. This mechanism includes a pivotally mounted trigger
67 and a sealed pressure sensitive switch SW-68. This switch is a
normally open, single-pull single-throw switch which requires only
a few ounces of force for actuation. When the trigger 67 is pulled,
the trigger actuator arm 67a bears down upon the switch SW-68,
closing it. This switch is connected into a circuit which includes
resistors R-69 and R-71 and a capacitor C-72. This circuit provides
rapid generation of noise-free pulses. When a switch SW-68 is open,
the voltage at output terminal 73 is high, and when the switch is
closed this output voltage steps to the low value.
Means is also provided for adjusting the travel and pull of this
alternative trigger arrangement. This means for adjusting the
travel includes an adjustable stop 74 and a fixed stop 76 As shown
in FIG. 5, the adjustable stop 74 can conveniently include a screw
threadably mounted in the gun frame 37. The pull is provided by a
resilient spring member 77 constrained between the actuator arm 67a
and the frame 37. The amount of pull is determined by the spring
constant of this spring. Because of the relatively low mass of the
trigger and actuator arm, the travel and pull can be adjusted to
very low values without danger of accidental discharge of the
weapon due to jarring.
A preferred control circuit based on NAND positive logic for a
two-barrel, single-trigger weapon is shown in FIG. 7. This circuit
can be used with either of the trigger arrangements and trigger
circuits heretofore described. In this circuit, logic pulses from
the trigger circuits are timed, sequenced, and distributed to the
firing circuits to provide firing of the barrels in a predetermined
order. This circuit also prevents simultaneous discharge of the two
barrels, or doubling. Doubling generally occurs because upon the
discharge of the cartridge in the first barrel, a weapon recoils,
drawing the trigger away from the shooter's trigger finger. This
provokes an unconscious pull of the trigger, a purely reflex action
on the part of all shooters. If this second pull were allowed to
actuate the second firing circuit and its cartridge, an apparent
double discharge would occur. The second discharge not only wastes
ammunition, but increases the recoil of the weapon and is thus
painful to the shooter.
This logic circuit includes an input terminal 81 adapted for
receiving logic pulse signals from the trigger circuits. From the
input terminals, the pulses pass to a first NAND-gate 82, then to a
second NAND-gate 83 and then to a one-shot multivibrator 84. The 0
output of the multivibrator 84 is connected to the clock input of a
J-K flip-flop 86 and also to one input terminal of NAND-gates 87
and 92. These NAND gates control the firing of the upper and lower
barrels, respectively. The output of NAND-gate 87 is connected to
the input of NAND-gate 88, and the output of NAND-gate 88 is
connected to output terminal 89 for connection to the upper barrel
firing circuit. The output of the NAND-gate 92 is connected to the
input of NAND-gate 93, and the output of NAND-gate 93 is connected
to an output terminal 94 for connection to the lower barrel firing
circuit. The 1 output of the flip-flop 86 is connected to a second
input terminal of the NAND-gates 87 and 92. The 0 output of the
flip-flop 86 is connected to the clock input of a second J-K
flip-flop 91. The 1 output of the flip-flop 91 is connected to a
third input terminal of NAND-gate 87, and the 0output is connected
to a third input terminal of the NAND-gate 92.
Operation of this logic circuit can now be briefly described as
follows. The upper barrel can fire only when the output at terminal
89 is high, which occurs only when all of the inputs to NAND-gate
87 are high. Similarly, the lower barrel can fire only when the
output at terminal 94 is high, which requires that all of the
inputs to NAND-gate 92 be high. Initially, the inputs to NAND-gate
87 from flip-flops 86 and 91 are high, and the remaining input from
multivibrator 84 is low. At the same time, the input to NAND-gate
92 from the flip-flop 86 is high and the inputs from multivibrator
84 and flip-flop 91 are low. With the trigger in its rest position,
the input at terminal 81 is high, and the output of NAND-gate 83 is
likewise high. When the trigger is pulled, the input at terminal 81
goes low and so does the output of NAND-gate 83. This triggers the
multivibrator 84, making its 0 output high and firing the upper
barrel. The time constant of the multivibrator 84 is chosen so that
its pulse duration is shorter than the shooter's reflex time, which
is on the order of 15 to 20 milliseconds. Since a J-K flip-flop is
actuated by the trailing edge of a positive pulse, i.e., a high to
low transition, at its clock input, flip-flop 86 is actuated at the
end of the positive pulse from multivibrator 84. At this time, the
logic states of flip-flop 86 are reversed, with its 0 output being
high and its 1 output low.
The reflexive trigger pull again causes the output of multivibrator
84 to go high. However, this time neither barrel fires since
neither NAND-gate 86 nor NAND-gate 92 has all of its inputs high.
At the end of this second positive pulse from multivibrator 84,
flip-flop 86 is again actuated, returning to its original state.
The 0 output of flip-flop 86 is connected to the clock input of
flip-flop 91, and the transition of this output from high to low
actuates flip-flop 91, making its 0 output high and its 1 output
low. At this time, the inputs to NAND-gate 92 from the two
flip-flop are both high, and the input from multivibrator 84 is
low. The next pull of the trigger drives the output of
multivibrator 84 high, thus firing the lower barrel.
Means is provided for resetting the flip-flops 86 and 91 to their
original logic states. This means includes a switch SW-96 which in
the preferred embodiment is actuated by opening the gun action.
Thus, with each loading or opening of the action, the control
circuit is reset to its original state.
Means is also provided for reversing the firing order of the two
barrels. This means includes a switch SW-97 which provides means
for manually reversing the initial logic state of flip-flop 91. The
RC circuits 98 and 99 associated with switch 97 are provided to
assure noise-free operation of the sequence selector switch.
An alternative control circuit for a two-barrel gun with a single
trigger is shown in FIG. 8. This circuit is somewhat simpler than
the circuit of FIG. 7 in that is includes only one J-K flip-flop.
The remaining elements of the circuit correspond generally to the
elements of the FIG. 7 circuit and have been designated
accordingly. In this circuit, the NAND-gates 187 and 192 each
derive two of their inputs from the outputs of NAND-gates 182 and
one-shot multivibrator 184. The third input of NAND-gate 187 is
connected to the 1 output of J-K flip-flop 186, and the third input
of NAND-gate 192 is connected to 0 output of this flip-flop.
Operation of this alternative circuit can be described briefly as
follows. Initially, the input to NAND-gate 187 from flip-flop 186
is high, and the inputs from NAND-gate 182 and multivibrator 184
are low. All three inputs to NAND-gate 192 are low. Upon the first
pull of the trigger, the outputs of NAND-gate 182 and multivibrator
184 90 high, thus firing the upper barrel. In this circuit, the
time constant of one-shot multivibrator 184 is adjusted such that
the duration of its positive pulse is longer than the reflex time
of the shooter, that is on the order of 50 to 200 milliseconds.
Thus, the flip-flop 186 remains in its initial state until after
the reflex pull has occurred. With flip-flop 186 in its initial
state, its 0 output is low, thus preventing firing of the lower
barrel. At the ends of the positive pulse from multivibrator 184,
flip-flop 186 is actuated and its logic states are reversed. At
this time, the input to NAND-gate 192 from flip-flop 186 is high,
and the inputs from NAND-gate 182 and multivibrator 184 are low.
All inputs to the NAND-gate 187 are low. The next trigger pull
causes the remaining inputs to NAND-gate 192 to go high, thus
firing the lower barrel.
Means is provided for resetting the flip-flop 186 to its initial
logic state. This means includes a switch SW-196 which is actuated
by opening the gun action. Thus, the logic circuit is reset to its
original state with each loading of the gun or opening of the
action.
Means is also provided for reversing the firing sequence of the
barrels. This means includes a switch SW-197 which permits manual
reversal of the initial logic state of flip-flop 186.
The firing delay introduced by either of the control circuits
heretofore described is only a small fraction of a millisecond, or
essentially zero, as compared with a mechanical lock which has a
lock time on the order of 7 to 20 milliseconds. This rapid response
is possible because firing is done on the leading edge of the logic
pulses from the trigger circuit, the only source of delay being the
propagation time of the logic circuits.
As will be apparent to those familiar with the art, the choice of
input pulse polarity and NAND positive logic is one of convenience
and utility, and different polarities and logic schemes can be used
if desired.
A preferred embodiment of a firing circuit is shown in FIG. 9. This
circuit is suitable for use with either of the trigger means and
control circuits heretofore described. In a multi-barrel weapon,
one such firing circuit is provided for each of the barrels.
The firing circuit comprises a silicon controlled rectifier
SCR-101, having a cathode 102, an anode 103, and a gate 104. The
cathode 102 is connected to the firing pin 26 of the weapon, and
the anode 103 is connected to a source of electrical energy through
safety switch 23. The gate 104 is connected to an input terminal
106 through a diode-D-107 and a resistor R-108. The input terminal
106 is adapted for connection to the output of either of the
control circuits shown in FIGS. 7 and 8.
operations of the firing circuit can be described briefly as
follows. In the rest condition, the input at terminal 106 is low,
thus holding the gate 104 at a low voltage so that the silicon
controlled rectifier does not conduct. When the input signal at
terminal 106 goes high, the silicon controlled rectifier is
triggered and firing pin 26 is connected to the source of
electrical energy. This causes current to flow through and ignite
the priming compound 42d, resulting in ignition of the powder 46.
The silicon controlled rectifier remains conductive until the flow
of current is interrupted by the combustion of the priming compound
and powder.
A resistor R-109 and capacitor C-110 are connected between the
anode and cathode of the silicon controlled rectifier These
components prevent self turn-on of the SCR upon sudden application
of voltage to the circuit, such as occurs when the breech or safety
switch 23 is closed. A resistor R-112 is connected between the gate
and cathode to provide further stabilization of the circuit.
All of the circuits of the ignition system can be powered by small
portable batteries which are easily mounted in the gun. Preferably,
the firing circuits should be powered by a battery which is
separate from the power source used for the control circuits to
avoid the possibility of introducing extraneous pulses into the
logic circuits upon the firing of the barrels. The use of a
capacitor across the battery for the firing circuits has been found
to enhance the speed of primer ignition. Switches, such as 23 and
24, can be provided for limiting the drain on the batteries when
the gun is not in use.
Although the ignition system has been described with reference to
two-barrel weapons having a single trigger, it is not limited
thereto. It can be utilized in single-barrel guns and in guns with
multiple barrels and multiple triggers. In weapons having one
trigger per barrel, control circuits are not required, and with a
simple polarity change, the trigger circuits can be connected
directly to the firing circuits. The system can be used in guns
having a single trigger and more than two barrels by adding one
flip-flop and two NAND gates per additional barrel.
FIGS. 10 and 11 illustrate an embodiment of the invention which is
particularly suitable for use in single barrel weapons such as
automatic, pump action, and single shot guns. The trigger mechanism
illustrated in FIG. 10 is generally similar to that shown in FIG. 5
except that the pressure sensitive switch SW-68 has been replaced
by a pressure sensitive thyristor or silicon controlled rectifier
SCR-121. The pressure sensitive SCR is a four-layer solid state
device having a structure generally similar to that of a
conventional thyristor. It includes an anode electrode 122, a
cathode electrode 123, and a gate electrode 124. The device is
normally non-conductive between its anode and cathode electrodes
and is rendered conductive, or turned on, by the application of
pressure in the region of the gate electrode 124. Once turned on,
the pressure sensitive SCR remains conductive until the current
flowing through it falls below a predetermined level. In the
embodiment illustrated in FIG. 10, the SCR-121 is disposed in such
a manner that the trigger actuator arm 67a applies a pressure to
the gate region of the SCR when the trigger 67 is pulled.
In the combined trigger circuit and firing circuit illustrated in
FIG. 11, the anode electrode 122 of the pressure sensitive SCR is
connected to a source of electrical energy, such as +22.5 volts,
through the safety switch 23. The cathode electrode 123 is
connected to the firing pin of a weapon, such as the firing pin 26
shown in FIG. 2. A resistor R-126 and capacitor C-127 are connected
in series between the anode and cathode electrodes to prevent
accidental triggering of the SCR. A resistor R-128 is connected
between the gate and cathode electrodes to provide further
stabilization of the circuit.
Operation of the embodiment shown in FIGS. 10 and 11 can be
described briefly. Let it be assumed that this system has been
installed in a weapon adapted for firing electrically primed
cartridges, such as the cartridge 43 in FIG. 2. The pressure
sensitive SCR is normally in its non-conductive state. When the
weapon is fired by pulling the trigger 67, the actuator arm 67a
exerts a pressure on the base region of the SCR, turning on the SCR
and connecting the firing pin 26 to the source of electrical
energy. This causes current to flow through the priming compound
42d of the cartridge 43, igniting the priming compound and
detonating the powder 46. The SCR remains conductive until the flow
of current is interrupted by the combustion of the priming compound
and powder.
The pressure sensitive SCR can readily be incorporated in
multi-barrel weapons having a separate trigger for each barrel. In
such weapons, a separate pressure sensitive SCR is provided for
each of the triggers, and a circuit of the type shown in FIG. 10 is
provided for each barrel.
The pressure sensitive SCR can also be incorporated in multi-barrel
guns of the type having a single trigger and mechanical means for
sequencing the firing of different barrels, prevention of doubling,
and elimination of unconscious or reflexive trigger pulls. Although
varying widely in complexity and structural details, single
triggers for multi-barrel weapons generally have at least one trip
member which is actuated by finger pressure upon the trigger. The
trip members typically engage the sear members or catches that hold
the hammers of gunlocks in their cocked positions. Actuation of the
trip member or members causes the hammers to be released, firing
conventional percussion type cartridges. One example of such a
trigger mechanism is described in U.S. Pat. No. 3,057,101, issued
Oct. 9, 1962 to H. L. Miller et al. Trigger mechanisms of this type
can be adapted for firing electrically primed cartridges by
replacing the sear members with pressure sensitive SCR's, removing
the hammers, and replacing the mechanical firing pins with
electrical firing pins and circuits of the type described
hereinbefore. With this system, the first conscious trigger pull
causes the trip member to bear against the pressure sensitive SCR
associated with the first barrel, and the next conscious pull
causes the trip member to engage the SCR of the second barrel.
From the foregoing, it is apparent that a new and improved system
for electronic ignition has been provided for firearms. This system
is capable of long and trouble-free performance since it includes
no electrical contacts other than the contact between the firing
pins and the primer heads of the cartridges. It permits wide
adjustments of trigger pull and travel and enables a single trigger
to control the firing of a plurality of barrels. Both electrical
and mechanical safety provisions are included to prevent accidental
discharge of the firearm. Only the presently preferred embodiments
of the invention have been described, and as will be apparent to
one familiar with the art, certain changes and modifications can be
made without departing from the scope of the invention as defined
by the following claims.
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