US 3650174 A
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.
Description (OCR text may contain errors)
United States Patent 7 [1 1 3,650,174 Nelsen 51 Mar. 21, 1972  ELECTRONIC IGNITION SYSTEM FOR 3,505,927 4/ l 970 Driscoll ..89/ l 35 FIREARMS 2,780,882 2/l957 Temple ..42/84 3,208,181 9/1965 Calhoun et al ..42/84  Inventor: Thomas Sloan Nelsen, 616 Foothill Road,
Sanford, Calif. 90005 FOREIGN PATENTS 0R APPLICATIONS  Filed: Jan. 12, 1970 2,629 1908 Great Britain ..42/84  Appl.No.: 2,274
Related U.S. Application Data  Continuation-impart of Ser. No. 820,932, May 1,
I969, abandoned.  Primary Examiner-Benjamin A. Borchelt Assistant Examiner-Stephen C. Bentley AttorneyFlehr, l-lohbach, Test, Albritton & Herbert ABSTRACT An electronic ignition system for firing electrically primed am- 2 l ..89 28 42 42,8 127, [5 l U s C l 9/ munition 1n a firearm. The system includes a trigger for con- 42/84 51 1 Int. Cl. ..F4lc 19/12 F41f 13/08 vemng mechafllcal "memem to elecmcal lgnals without the 58] Fie|d f Search 42/42 89/58 127 135 need of electrical contacts, and logic circuitry which permits IIIIIIIIIIIIIIIIII u selective firing of multiple barrels with a single trigger. Van'- [56 References Cited ous electrical and mechanical safety features, including 7 retractable firing pins, are provided to prevent accidental UNITED STATES PATENTS discharge of the weapon.
937,396 10/1909 Venier ..42/42 11 Claims, 11 Drawing Figures Fl RI NG PI N TRIGGER CONTROL FIRING AND MEANS CIRCUIT CIRCUIT CARTRIDGE I l3 /6 l? PIN FIRING FIRING FIRLNNGD SEQUENCE CIRCUIT SELECTOR CARTRIDGE 23 ,22 POWE R I POW ER S U P PLY S U P P LY PAIENIEDMIIRZI I972 3,650,174
SHEET 1 OF 4 E r /5 TRIGGER CONTROL FIRING 'gz PIN N MEA s CIRCUIT CIRCUIT CARTRIDGE I H I I6 /7 FIRING FIRING FIRING PIN SEQUENCE CIRCUIT AND SELECTOR CARTRIDGE POWER POWER SUPPLY SUPPLY TO CONTROL CIRCUIT l2 TO CONTROL CIRCUIT I2 INPUT FROM CONTROL CIRCUIT INVENTOR.
THOMAS S. NELSEN ATTORNEYS T0 FIRING PIN 26 PAIENIEBMARZI I972 3.650.174
SHEET 2 OF 4 INVENTOR. THOMAS 5. NELSEN ATTORN E Y5 PATENIEBMIIRZI I972 3.650.174
SHEET 3 [IF 4 4 INPUT FROM 8! 82 83 TRIGGER CIRCUIT 87 88 TO uPPER BARREL FIRING CIRCUIT 93 92 TO LowER BARREL FIRING CIRCUIT INPUT FROM I82 TRIGGER CIRCUIT I8! 'I I88 TO uPPER BARREL FIRING cIRcuIT 1 I92 I93 Rs I94 C s 0 TO LowER BARREL 'FIRING CIRCUIT INVENTOR. THOMAS S NELSEN WJM ATTORNEYS PAIENTEUMARZI m2 3 650,174
' SHEET u BF 4 77 2670 I9 4% 51% & SCR- I21 l' C- I27 A 0 TO FIRING PIN 26 INVENTOR. THOMAS S. NELSEN BY ZA//MZ M ATTORNEYS ELECTRONIC IGNITION SYSTEM FOR FIREARMS 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 l4 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 360 and a large outer bore 36b. An annular shoulder 360 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 3811 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 metalllic 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 to they cannot make contact with the cartridges.
While the firing pins have been described with reference to tin over-under type of gun. the system of retractable insulated tiring pins actuated by the breech locking mechanism can be iiipplied equally well in side-by-side weapons. drillings. tierlings. and single-barrel guns. including both single-shot weapons and repeaters ot' 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 tire 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-S3 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 lR-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 adustable 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 5] 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.
in 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 072. This circuit provides rapid genera- .1011 of noise-free pulses. When a switch SW-68 is open. the oltage 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 iiiown 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 arring.
t preferred control circuit based on NAND positive logic tor 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 uncon- 5CIOUS 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 o 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 nDut 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 tlip-flop 91 is connected to a third input terminal of NAND- gate 87. and the Ooutput 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 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 shooters reflex time, which is on the order of to milliseconds. Since a J-K flipflop 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 outputhigh 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 9l 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 thethird input of NAND-gate l92 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 flipflop 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-l97 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 multibarrel 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-D407 and a resistor R-l08. 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 trig- 'gered 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-ll0 are connected between the anode and cathode of the silicon controlled rectifier These components prevent self tum-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-l12 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 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. except that the pressure sensitive switch 5W-68 has been replaced by a pressure sensitive thyristor or silicon controlled rectifier SCR-121. The pressure sensitive ISCR is a four-layer solid state device having a structure generally similar to that ofa 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 eonductive, 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.
ln 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 +225 volts, through the safety switch 23. The cathode electrode 123 is connected to the firing pm of a weapon, such as the firing pin 26 shown in FIG. 2. A resistor R-l26 and capacitor C-l27 are connected in series between the anode and eathode electrodes to prevent accidental triggering of the ECR. A resistor R-l28 is connected between the gate and cathode electrodes to provide further stabilization of the cireuit.
Operation of the embodiment shown in FIGS. 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 detonatmg the powder 46. The SCR remains conductive until the flow of current is inter- :i'upted by the combustion of the priming compound and powder.
The pressure sensitive SCR can readily be incorporated in iinulti-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 ll'l FIG. 10 is provided for each barrel.
The pressure sensitive SCR can also be incorporated in imulti-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 pr reflexive trigger pulls. Although varying widely in complextty 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 described in U.S. Pat. No. 3,057,101, issued Oct. 9. 1962 to H. L. Miller et al. Trigger mechanisms ofthis type can be adapted for firing electrically primed cartridges by replacing the sear members with pressure sensitive SCRs. removing the hammers. and replactng the mechanical firing pins with electrical firing pins and eircuits 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 ofthe second barrel.
From the foregoing, it is apparent that a new and improved tystem 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.
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 mul- :ivibrator 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.
S. 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.
ti. 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.
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.
l3. 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 shooters 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 recti- 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.