The invention relates to handgun safety apparatus and, more particularly to an aftermarket appliance for signaling low handgun ammunition counts.
In U.S. Pat. No. 7,716,863 Johnson et al. disclose an apparatus for counting and storing a number of rounds fired from a gun that includes a microcomputer; a non-volatile memory connected to the microcomputer; and a piezoelectric transducer connected to the microcomputer and mounted on the gun. The piezoelectric transducer has a power source that generates power during operation of the gun. The piezoelectric transducer may also sense the firing of the gun.
In U.S. Patent Application Publication 2009/0211139 Ufer et al. disclose a microcontroller operated module that is affixed to a firearm. The module includes an accelerometer for measuring the acceleration of each round fired by the firearm, a flash memory for storing the shot profile data that includes shot count and recoil data that is transmitted to a remote location.
In U.S. Patent Application Publication 2003/0061753 Glock discloses a pistol that includes a carriage or slide connected to a gun barrel. The carriage slides back on a handle of the pistol during discharge against the force of a return spring. The pistol includes a device for determining the number of shots fired with electronics attached to the handle. The electronics include a microprocessor with storage, a piezoelectric sensor connected to the microprocessor, a current supply, and a reading device for reading the storage that is external to the pistol. The piezoelectric sensor receives recoil impulses during discharge and sends a signal to the microprocessor in response to the impulses. A second sensor sends a second signal to the microprocessor when the carriage slides back. The microprocessor sends a count impulse to storage during a time interval between the first signal of the piezoelectric sensor and the second signal, which corresponds to the time interval between discharge and sliding back of the carriage during a discharge.
In U.S. Pat. No. 7,802,391 Quinn et al. disclose a handgun with a rounds counter that employs an accelerometer for counting rounds. The rounds counter is adapted to a variety of weapons, such as on military vehicles and patrol watercraft having different types of guns.
In U.S. Patent Application Publication 2008/0016744 Joannes et al. disclose a device for detecting and counting shots fired by an automatic or semiautomatic firearm with a barrel and a slider that undergoes accelerations in the axial direction for every fired shot. The accelerations form a signature for the firearm and the for type of ammunition. Electronics include an accelerometer with a passband and a microprocessor for analyzing the signals of the accelerometer. The microprocessor counts the number of shots fired using the signal of the accelerometer and the acceleration signature.
An object of the invention is to provide an aftermarket handgun ammunition count signaling apparatus.
The above object is achieved with placement of a circuit board on a gun slide in a semiautomatic handgun of the type where the slide moves rearwardly over the gun barrel and then forwardly to battery position as long as there is ammunition. A thin circuit board is mounted on the semiautomatic handgun slide below the line of sight established by the gun sights. One portion of the circuit board has electronic circuitry for sensing slide acceleration rearwardly and reverse acceleration after ejection of a spent round. A counter associated with a microcontroller counts fired rounds based upon acceleration cycles. A low count generates an associated humanly perceptible signal from a transducer, such as an LED or other light, for signaling a round count at a preset level, such as two rounds remaining. The circuitry also includes logic that signals slide lock back in a rearward position, for example when ammunition is out, with a humanly perceptible signal, such as a second LED or other light, also issuing from a signal source on the circuit board. Lock back occurs when the last round of ammunition is fired or when there is a misfeed. All circuitry is carried on a thin saddle shaped circuit board, in one embodiment facing downwardly toward the slide, together with a thin battery that powers the circuitry. The saddle shape has portions that are wider than the rear gun sight. This allows the circuit board to be forward of the rear gun sight, yet the wider portions allow placement of LED lights that can be seen from behind the gun sight. The circuit board may be added to semiautomatic handguns as a safety feature after the time of manufacture. When the slide is locked back, the condition is easy to see in daylight but almost impossible to detect in the dark. Similarly low round count remaining is an important piece of information that can affect gun user safety. The circuit board carries rearwardly facing LEDs that indicate these conditions.
With reference to
With reference to
With reference to
A rearward board portion has the right-side LED light 25 as well as a left side LED light 33 symmetrically positioned on opposed side wings where the lights are not blocked by the rear sight. Because the LED lights are located on the side wings of the board, they are seen to the left and right of rear sight 17 and are visible behind the rear sight. It should be noted that while the circuit board is situated between the front and rear sights, signal lights in the side wings are visible to a shooter behind the slide and rear sight.
The topside of the circuit including a microcontroller and ancillary electronic circuits 51 and battery 49 are deposited, as well as an accelerometer, not shown. The thin film electronics circuitry are on the circuit board that is fastened to slide 21 associated with a semiautomatic handgun and move with the slide, thus experiencing the same acceleration as the slide. Reset button 29 is fabricated on a forward portion 27 of the circuit board. The forward portions is slightly recessed, by about half the board thickness, so that the button does not extend in height much above the board thickness 45 in order to avoid any interference with gun aiming optics.
In
With reference to the circuit diagram of
Correspondingly, the accelerometer produces electrical charge that is positive when acceleration occurs in the rearward direction and negative when acceleration occurs in a reverse direction. One side of the accelerometer 53, negative, communicates with a voltage reference amplifier 54, while the other side of the accelerometer, positive, goes to a positive input of an operational amplifier 55. A feedback network 56 is a charge accumulator that stores charge from accelerometer 53 initial motion then feeds the charge around the operational amplifier 55 which boosts the signal through one of its inputs and provides an output to microcontroller 57 at terminal 59.
A positive side of the accelerometer 53 is also connected to voltage reference 54, along line 64. In other words, the same voltage reference 54 is now provided to microcontroller 57 and to the positive terminal of operational amplifier 55. The operational amplifier serves as an A-to-D converter with the accelerometer providing an analog input. A negative terminal of accelerometer 53 provides a wake-up signal to microcontroller 57 at terminal 61. One of the main functions of the wake-up signal is to prolong the life of power supply battery 49. The wake-up signal allows power from the battery to flow to a power-on-wake-up signal line 65 that enables operational amplifier 55 to produce a digital shock signal at terminal 59, with origins at accelerometer 53. This signal is used to detect and count shots fired.
One of the primary functions of the microcontroller is to illuminate warning lights 25 and 33, both LEDs. The microcontroller 57 includes a counter whereby it knows the number of rounds of the fully loaded handgun and can count down as rounds are fired. The microcontroller uses shock signal inputs at terminal 59 to count down as shots are fired. When there are two rounds remaining, the light 25 is illuminated. The slide lock light 33 is illuminated when the microcontroller detects accelerometer motion in the positive direction but fails to detect an opposed negative accelerometer motion within a few milliseconds, indicative of slide lock back. Operation of the microcontroller is governed by a program in storage memory 75 explained by the logic diagrams of
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In
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The slide lock LED is preferably red, while the low round remaining LED is another color, say yellow, so that the warning signals can be distinguished in darkness, although both are simultaneously potentially visible on either side of, and from behind, the rear gun sight. It is not necessary to use LEDs. Any humanly perceptible warning signal could be used, preferably visual. The reset signal is only reliable after a full reload.
All circuitry is fabricated as thin film integrated circuits and mounted on the circuit board. Total thickness of the integrated circuits on the board is between one and two mm so that the thickness of the board and the thickness of the integrated circuits is less than 4 mm, the nominal clearance for the aiming line of sight of the handgun.
The integrated circuitry has a top insulative layer so that the metallic slide cannot short the circuitry if the circuitry contacts the slide when the circuit board is mounted upside down. In this case, a slight air gap exists between the electronic circuitry and the slide so that the piezo accelerometer is not biased by mechanical contact with anything, although insulated from contact with the slide by protective coatings. The saddle shape of the circuit board allows for a slight air gap between the circuit board and the gun slide while still preserving the line of sight established by the gun sights.
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