Title:
LASER MARKMANSHIP TRAINER
United States Patent 3633285
Abstract:
A laser transmitting device for marksmanship training. The device is readily mountable to the barrel of a firearm and transmits a light beam upon the actuation of the firing mechanism of the firearm. The laser device is triggered in response to an acoustical transducer which detects sound energy developed by the firing mechanism of the firearm, and means are provided to prevent false triggering of the device by extraneous sounds. The light beam is detected by a target having a plurality of light detectors, whereby an indication of the accuracy of the aim may be obtained.
Application Number:
05/017788
Publication Date:
01/11/1972
Assignee:
Litton Systems, Inc. (Beverly Hills, CA)
International Classes:
F41G3/26; F41G3/00; (IPC1-7): F41C27/00; F41G3/26
Field of Search:
42/1A 35
Primary Examiner:
Borchelt, Benjamin A.
Assistant Examiner:
Jordan C. T.
Claims:
What is claimed is
1. A device, adapted to be mounted on a firearm, for transmitting a beam of light upon actuation of the firing mechanism of the firearm, said device comprising:
2. The device of claim 1 wherein said triggering means includes a transducer for converting the acoustical energy to electrical energy.
3. The device of claim 2 wherein said transducer is a crystal
4. The device of claim 2 wherein said triggering means includes means for rejecting energy outside of the frequency range of the energy developed by the firing mechanism.
5. The device of claim 4 wherein said means for rejecting energy includes a highpass filter network.
6. The device of claim 4 wherein said means for rejecting energy includes a passband filter network.
7. The device of claim 4 wherein said means for rejecting energy includes a crystal which substantially responds to energy in the frequency range of the energy generated by the firing mechanism.
8. The device of claim 1 wherein said transmitting means includes a laser diode; and driver means for activating said laser diode with said driver means including an electrical storage element, and means for preventing repeated actuations of the laser diode for a selected time period after it has been previously activated.
9. The device of claim 8 further comprising a source of potential coupled to said driver means with said means for preventing repeated actuations including a resistor coupled in series with said source of potential and said electrical storage means.
Description:
BACKGROUND OF THE INVENTION
This invention relates to marksmanship training devices and particularly to such devices adapted for mounting to a firearm and which utilize a light beam for simulating real ammunition.
"Dry firing" is a term commonly used to describe the process of simulating the firing of a firearm without the use of real ammunition. This type of practice improves proficiency in such phases of marksmanship as holding the correct "sight picture" and coordinating breathing with trigger squeeze. It has been found that such training can be improved if some means for obtaining an indication of the accuracy of the aim during dry firing is used, such as a laser light beam and a light detector-type target. Also it would be desirable if the laser device could be readily mounted to the trainee's individual, personal firearm without requiring electrical or mechanical connections to trigger the laser transmitter. Further, the versatility of the device, and hence its value as a training tool, would be enhanced if the laser device could be used in conjunction with blank ammunition when it is desired to familiarize the trainee with noise and recoil effects; and if live ammunition could be used for periodic checks on a real target without requiring removal of the laser transmitter device.
SUMMARY OF THE INVENTION
Accordingly it is a primary object of the subject invention to provide an improved laser marksmanship trainer which possesses the foregoing desirable characteristics.
Another object is to provide a completely self-contained, "clamp on" laser transmitter device which may be readily attached to a trainee's individual firearm.
A further object is to provide a laser trainer device which is triggered in response to acoustical energy developed by the firing mechanism, thereby not requiring any electrical or mechanical connections to the firing mechanism.
Still another object is to provide a laser trainer device which is triggered by acoustical energy as described above and which filters out extraneous sounds to prevent false triggerings.
In accordance with one preferred embodiment of the subject invention, the above-described advantages are obtained by a laser transmitter which is triggered by acoustical energy developed by the firing mechanism of the firearm. The triggering means includes a sound energy to electrical energy transducer, and filtering is provided to reject extraneous sounds. Additionally the charging time of the laser's driver unit is selected by design to prevent repeated triggerings of the laser unit for a selected period after it has once been fired. This just described feature prohibits false triggering of the device by signals resulting from such sources as the ejection mechanism of the firearm.
BRIEF DESCRIPTION OF THE DRAWINGS
Other advantages of the invention will hereinafter become more fully apparent from the following detailed description of the drawings, which illustrate the preferred embodiments, and throughout which like reference numerals indicate like parts, and in which:
FIG. 1 is a side and perspective view of the laser transmitter of the present invention as applied to a rifle of conventional design, and of a suitable target, respectively;
FIG. 2 is a side view of the laser transmitter device of the subject invention;
FIG. 3 is a sectional view of one end portion of the device of FIG. 2;
FIG. 4 is an end view of the tubular portion of the device of FIG. 2 depicting the "on-off" switch; and
FIG. 5 is a block and schematic diagram of the laser transmitter of FIG. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the accompanying drawings, the laser transmitter 10 is mounted to the outer end of a barrel 12 of a rifle 14 by means of a pair of clamps 16. The rifle 14 may be any conventional type but for the purposes of this description it will be assumed to be of a type having a firing mechanism (not shown) with a hammer and a firing pin activated by a trigger 18.
In operation the unit 10 is mounted beneath the barrel 12 by means of the clamps 16 and is "boresighted" so that the light beam 20, emitted by the unit 10, intercepts the same portion of a target 22 as would a projectile fired through the barrel 12. Normally the inner surfaces of the clamps 16 may be machined to match a particular type of rifle barrel and just tightening the clamps provides a sufficiently accurate "boresight". However for greater accuracy in "boresighting", shims (not shown) may be positioned between sections 24 and 26 of one of the clamps, as required.
The target 22 may comprise a plurality of suitable photodetecting devices 28. In a system where the light-producing element is a gallium arsenide (GaAs) laser diode it has been discovered that infrared-type solar cells serve as excellent detector elements because of their rapid response time and resistance to "burnout" from ambient sunlight. Each solar cell 28 may be capacative coupled to a monostable multivibrator circuit (not shown) with this last-mentioned circuit controlling an indicator light, in an array of lights (not shown), to visually display the marksman's score.
The laser transmitter 10 is powered by a battery 30 which is electrically connected to the circuits of the unit 10 by an "on-off" switch 32. A capacitor 34 is shunted across the battery 30 to provide isolation filtering. The low voltage of the battery 30 (12 volts, for example) is converted to a higher voltage (135 volts, for example) by a power supply unit 36. The output voltage of the power supply unit 36 is applied to a laser driver unit 38 on a lead 40. The laser driver unit 38 provides sufficient current to pulse (produce light emission) a laser diode 42 in response to a triggering signal applied on a lead 44 from the acoustical pickup and amplifier unit 46.
The power supply unit 36 includes an ascillator stage 45 which comprises a transistor 46, resistors 48 and 50 and capacitors 52 and 54. The output signal of the stage 45 is coupled through a transformer 56 and a capacitor 58 to a rectifier circuit-comprising diodes 60 and 62.
The voltage from the power supply unit 36 is applied on the lead 40, through a resistor 41, to a capacitor (energy storage element) 64 of the laser driver unit 38. When a silicon-controlled rectifier 66 is gated on by a trigger signal applied on a lead 44, the energy stored in the capacitor 64 causes a high-magnitude (30 amperes, for example), short duration (200×10-9 seconds, for example) current pulse to flow through laser diode 42 causing it to emit a short pulse of light energy.
One of the primary advantages of the subject invention is that the laser-transmitting unit 10 is self-contained and does not require electrical connections or mechanical linkages to the firing mechanism of the rifle 14. This not only allows for ease of installation, but simplifies making the unit waterproof and shock resistant. These just mentioned advantages are achieved by means of a unique triggering concept mechanized by the acoustical pickup and amplifier unit 46.
Referring now momentarily to the unit 46 shown best in FIG. 5, a transducer device 68, which may be a crystal such as used in crystal microphones, detects the acoustical energy produced by the firing mechanism of the rifle 14 when the trigger 18 is operated. Acoustical energy is generated by the firing mechanisms of all rifles due to the impact of metal upon metal (for example, the hammer striking the firing pin) and substantial energy is produced in the upper portion of the acoustical frequency range. This acoustical energy is primarily transmitted to the crystal 68 through the barrel 12, the clamps 16 and the structure of the laser unit 10. The crystal 68 converts the acoustical energy (sound vibrations) into an electrical signal which is applied through a filter section 70 and trigger amplifier stages 72 and 74 to output trigger section 76.
In the illustrated embodiment, the filter section 70 includes resistors 77, 78, 79 and 80 as well as capacitors 81, 82 and 83 which are arranged in a "high pass" filter configuration --i.e., lower frequency signals are attenuated more than higher frequency signals. It has been shown that for most applications this configuration is quite acceptable because most interfering signals such as the impact of the stock of the firearm on a table or the ground, are of sufficiently low frequency as to be substantially rejected by the filter 70.
For some applications it may be desirable to make the filter 70 a "passband" filter --i.e., substantial attenuation of energy at all frequencies except in a selected range. The frequency of the center of the "passband" would be selected to be compatible with the frequency of the energy generated by the firing mechanism of a particular firearm. Also the crystal 68 could be selected to have the desired passband frequency response, in which case filter 70 could be eliminated.
The signal generated by the crystal 68, after being filtered by section 70, and applied by amplifier stages 72 and 74 to output trigger section 76 causes the transistor 84 to conduct. When the transistor 84 conducts the gate terminal 85 of the silicon-controlled rectifier 66 is switched to a positive potential with respect to its cathode and the silicon-controlled rectifier 66 conducts. The silicon-controlled rectifier 66 discharges the capacitor 64 through the laser diode 42, and thereby causes the laser diode to emit a beam of light.
In certain types of rifles acoustical energy in the same frequency range as that produced by the firing mechanism is generated shortly after actuation of the firing mechanism --e.g., energy produced by the bolt movement during ejection of a shell casing. To prevent such extraneous signals from firing the laser 42, a resistor 41 may be added between the lead 40 and the capacitor 64. The value of the resistor 41 is selected so that the energy stored by the capacitor 64 will not reach the threshold level (insufficient to pulse the laser) until a second or two after the capacitor 64 is first discharged by a correct trigger signal.
As shown best in FIG. 3, the previously mentioned components may be compactly packaged in a tubular housing 90. Contained within the housing is a support frame 92 on which is mounted the power supply section 36, the acoustical pickup and amplifier unit 46, the laser driver unit 38 and the laser diode 42. An optical lens for focusing the light beam is mounted in the forward end section of the tube 90. An appropriate apperture or mask (not shown) may be mounted in the forward end of the tube 90 on the light output side of the lens 94 to provide a light beam of the same cross section as that of the projectile simulated.
In operation of the laser trainer device of the subject invention, the unit 10 is mounted to the rifle 14 as explained previously and the rifle is sighted on the target 22 in the normal manner. Upon actuation of the trigger 18 the firing mechanism of the rifle generates acoustical energy which is detected and amplified by the unit 46. The unit 46 also provides a signal to the drive unit 38, which signal causes the laser 42 to emit a pulse of light energy. This light energy is detected by one of the solar cells 28 of the target 22. The solar cells 28, when illuminated, produces an electrical signal which is coupled through multivibrator circuits (not shown) to an array of lights (not shown) for visually displaying the score.
Thus there has been described a new and improved marksmanship training device which is easy to install on any conventional firearm and which is efficient to operate. Because of the unique triggering technique incorporated into the laser transmitting device, training may be extended to include the use of blank ammunition to simulate the recoil and noise features. It should be noted that one of the advantages of subject invention is that when blank ammunition is used the laser beam is transmitted prior to the time smoke exits from the barrel, therefore avoiding interference with the light transmission. Also it should be noted that live ammunition may be utilized without removing the laser device from the firearm --hence allowing for periodic testing with live ammunition on a different target.
While the basic principles of this invention have been herein illustrated by the preferred embodiments, it will be appreciated by those skilled in the art that variations in the disclosed arrangement, both as to its details and as to the organization of such details may be made without departing from the scope and spirit thereof. In particular the circuit details of the power supply 36, the laser driver 38, and the amplifier stages 72, 74 and 76 may be readily modified within the scope of the subject invention.