Abstract:
A night vision device is disclosed. The device includes a housing that houses an intensifier tube and a proximity sensor mounted on the housing. An ON/OFF switch is operatively coupled to the intensifier tube and to the proximity sensor such that operation of the ON/OFF switch to the “ON” position automatically activates the proximity sensor. A method of operating the night vision device with the proximity sensor is also disclosed.

Description:
BACKGROUND OF THE INVENTION 
     Night vision devices, such as night vision goggles (NVG&#39;s) are well known for being able to enable a user of such a device to easily see in darkened environments. These devices are often used in military applications to enable soldiers to see without the use of extraneous visible lighting, such as flashlights, which may give away their position to the enemy. The NVG intensifies the available low-level ambient light, and provides an image having a generally greenish glow that enables the user to see his surroundings. 
     The NVG is often mounted on a soldier&#39;s helmet and is movable between an operational position in front of the soldier&#39;s eyes, and a stowed position, such as above the soldier&#39;s eyes. However, in the stowed position, the eyepieces are generally directed outward, away from the soldier, and it may be possible for an enemy to see the green glow from the eyepieces, thus giving away the soldier&#39;s position. 
     To counter this problem, magnets have been incorporated in the helmet is mount so that, when the NVG is in its use position, the magnetic field generated by the magnet activates a magnetically operable switchpot, turning the NVG “ON”. When the NVG is flipped to is stowed position, the magnet slides within its housing away from the magnetic switchpot, removing the magnetic field, and turning the NVG “OFF”. However, problems exist with this technology. When the soldier is not looking in a level direction, but is looking up or down, the magnet may inadvertently slide to the “OFF” position, rendering the NVG inoperable at an inopportune time. Additionally, if the soldier is rolling or tumbling, the magnet may again slide to the “OFF” position. Further, the magnet slides within its housing with an audible “click” that may disturb soldiers fearful of generating any sound whatsoever that may give away their position to the enemy. 
     It would be beneficial to provide a method of maintaining the NVG in the “ON” position when the NVG is in front of the soldier&#39;s eyes, regardless of the soldier&#39;s orientation, yet automatically switchpot to the “OFF” position when the NVG is moved away from the soldier&#39;s eyes. 
     SUMMARY OF THE INVENTION 
     Briefly, the present invention provides a night vision device. The device includes a housing that houses an intensifier tube and a proximity sensor mounted on the housing. An ON/OFF switch is operatively coupled to the intensifier tube and to the proximity sensor such that operation of the ON/OFF switch to the “ON” position automatically activates the proximity sensor. 
     Additionally, the present invention provides a method of operating a night vision device. The device comprises a housing that houses an intensifier tube and a proximity sensor mounted on the housing. An ON/OFF switch is operatively coupled to the intensifier tube and to the proximity sensor. The method comprises the step of turning only the ON/OFF switch to the ON position and activating both the intensifier tube and the proximity sensor. 
     Further, the present invention provides a method of operating a night vision device. The device comprises a device housing that houses an intensifier tube and a proximity sensor mounted on the device housing. An ON/OFF switch is operatively coupled to the intensifier tube and to the proximity sensor. The method comprises the steps of mounting the night vision device on a support; turning the ON/OFF switch to the ON position; moving the proximity sensor to a close proximity of a body to activate the intensifier tube; and removing the proximity sensor from a close proximity of the body to deactivate the intensifier tube. 
     Also, the present invention provides a night vision assembly comprising a support structure and a night vision device mounted on the support structure. The night vision device comprises a device housing that houses an intensifier tube and a proximity sensor mounted on the device housing. The proximity sensor is operatively coupled to the intensifier tube. An ON/OFF switch is operatively coupled to the intensifier tubes and to the proximity sensor such that operation of the ON/OFF switch to the “ON” position automatically activates the proximity sensor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed description preferred embodiments of the invention, will be better understood when read in conjunction with the appended drawings, which are incorporated herein and constitute part of this specification. For the purposes of illustrating the invention, there are shown in the drawings embodiments that are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings, the same reference numerals are employed for designating the same elements throughout the several figures. In the drawings: 
         FIG. 1  is a schematic view of a night vision device with proximity sensor according to a first embodiment of the present invention in a “use” position. 
         FIG. 2  is a schematic view of the night vision device with proximity sensor in a “stowed” position. 
         FIG. 3  is a perspective view of the night vision device with proximity sensor. 
         FIG. 4  is an electrical schematic of the proximity sensor used in the night vision device. 
         FIG. 5  is a perspective view of a night vision device with proximity sensor according to a second embodiment of the present invention, with the night vision device mounted on a rifle. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Certain terminology is used herein for convenience only and is not to be taken as a limitation on the present invention. The terminology includes the words specifically mentioned, derivatives thereof and words of similar import. As used herein, the term “rear” is defined to mean a direction closer to a user when the night vision device is in a use position as described herein and “front” is defined to mean a direction farther from a user when the night vision device is in a use position as described herein. The following describes preferred embodiments of the invention. However, it should be understood based on this disclosure, that the invention is not limited by the preferred embodiments of the invention. 
     Referring to the figures in general, a night vision device according to the several embodiments of the present invention is disclosed. The device includes a proximity sensor comprised of an infrared emitter and detector assembly that is used to detect when the night vision device is in close proximity to a user. When the night vision device is within a predetermined distance of the user, the proximity sensor allows the night vision device to operate, but when the night vision device is outside of the predetermined range, the proximity sensor will not allow the night vision device to operate. 
     Referring now in particular to  FIG. 1 , a night vision device  100  according to the present invention is shown. The night vision device  100  is preferably mounted on a support bracket  40  that is fixed to a helmet  50  of a user  52 , such as a soldier. The support bracket  40  preferably includes a pivoting mount  42  that allows the user  52  to move the night vision device  100  between a first position, when the night vision device  100  is aligned for use with the eyes  54  of the user  52 , and a second position, shown in  FIG. 2 , when the night vision device  100  is moved away from the eyes  54  of the user  52  in a non-use, or stowed, position. As seen in  FIG. 2 , a common location of the second position is above the eyes  54  of the user  52 , toward the top of the head of the user  52 . 
     Referring now to  FIG. 3 , the night vision device  100  includes a housing  102  that houses intensifier tubes  104  that are used to intensify the image being observed through the device  100 . As shown in  FIG. 3 , two intensifier tubes  104  are used, making the night vision device  100  a binocular device. However, those skilled in the art will recognize that only one intensifier tube  104  need be used, making the device a monocular device. Such a monocular device is described below with reference to a night vision device  200 . 
     Referring to both  FIGS. 1 and 3 , the housing  102  also has a rear portion  106  that faces the user  52  and a front portion  108  that faces away from the user  52 . The intensifier tubes  104  enable the user  52  to see objects in a low light environment, such as in a darkened room or at night. The intensifier tubes  104  are powered by a power source  110 . Preferably, the power source is a single 1.5 volt DC battery, although those skilled in the art will recognize that any number of batteries and other voltages may be used. 
     A main ON/OFF/VARIABLE GAIN switchpot  114  provides an electrical connection between the power source  110  and the intensifier tubes  104  and varies the gain of the intensifier tubes  104 . While an ON/OFF/VARIABLE GAIN switchpot  114  is desired, those skilled in the art will recognize that an ON/OFF switch may be used instead. A separate ON/OFF/MOMENTARY ON switch  112  operates to either turn an infrared LED ON, OFF, or MOMENTARY ON to provide illumination for the night vision device  100  in extremely low light conditions. 
     A proximity sensor  120  is also mounted on the housing  102 . As shown in  FIG. 3 , the proximity sensor  120  is mounted on the rear portion  106  of the housing  102 . The proximity sensor  120  is comprised of an infrared emitter  122  and a corresponding infrared detector  124  that is tuned to pick up the particular wavelength of light that is emitted from the infrared emitter  122 . 
     When the night vision device  100  is in the first, or use, position, as shown in  FIG. 1 , the proximity sensor  120  is activated, sending an output signal to the intensifier tubes  104 , to turn the intensifier tubes  104  on. When the intensifier tubes  104  are on, the intensifier tubes  104  emit a greenish glow that, in a darkened environment, can be seen over a great distance. However, the proximity sensor  120  ensures that the intensifier tubes  104  only emit the glow when the night vision device  100  is in the first position and the glow is directed into the user&#39;s eyes  54 . When the night vision device  100  is in the second, or stowed, position, as shown in  FIG. 2 , the proximity sensor  120  is deactivated, and the output signal is not sent to the intensifier tubes  104 . The intensifier tubes  104 , therefore, turn off, and the greenish glow is not emitted from the intensifier tubes  104 . 
     An electrical schematic of the proximity sensor  120  is shown in  FIG. 4 . The proximity sensor  120  is comprised of the infrared emitter  122  and the infrared detector  124 , as well as an adjustment potentiometer (“pot”)  126  that adjusts the sensitivity of the proximity sensor  120 . The infrared emitter  122  emits a low power infrared signal that must be detected by the infrared detector  124  in order to activate the intensifier tubes  104 . The infrared emitter  122  may be an LED or any other suitable source for emitting infrared light. Preferably, the infrared emitter  122  emits an infrared light having a wavelength of at least 900 nm. The infrared detector  124  is tuned to detect light waves that are transmitted at the infrared emitter wavelength. 
     The operational threshold of the proximity sensor  120  is set by adjustment of the adjustment pot  126 . Once the appropriate operational threshold is determined, based on the required sensing range and types of reflective surfaces applicable to the anticipated usage scenarios, the adjustment pot  126  may optionally be eliminated in production units and replaced with a fixed resistor (not shown). 
     An optical filter (not shown) may optionally be included in front or, or as part of the infrared detector  124  to further tune the sensitivity of the infrared detector  124  to match the infrared emitter  122  and to reject ambient light at extraneous wavelengths. In addition, the infrared emitter  122  can be modulated or pulsed “ON” and “OFF”, and the circuit comprising the proximity sensor  120  can be arranged to be sensitive to this modulation or pulsing pattern in order to reduce the required power, improve the sensitivity, and/or better reject the interference of ambient light. 
     Preferably, input power of approximately 2.7 volts (nominal) powers the infrared emitter  122 . A voltage step up 128 steps up the voltage from 1.5 volts to about 2.7 volts to operate the proximity sensor  120  and the intensifier tubes  104 . The power is provided to the infrared emitter  122  through activation of the ON/OFF/VARIABLE GAIN switchpot  114 . The ON/OFF/VARIABLE GAIN switchpot  114  provides direct power to both the intensifier tubes  104  as well as the proximity sensor  120 , without the need for a separate ON/OFF/VARIABLE GAIN switchpot for the proximity sensor  120 . 
       FIG. 4  shows the infrared emitter  122  supplied with a fixed operating power. However, those skilled in the art will recognize that the power to the infrared emitter  122  may alternatively be reduced in response to the level of detected power in order to reduce the infrared signature and power consumption of the proximity sensor  120 . 
     When the night vision device  100  is brought to the use position in front of the wearer&#39;s eyes for use, as shown in  FIG. 1 , the infrared light emitted from the infrared emitter  122  impinges on a reflective surface, such as the wearer&#39;s forehead  56  or the helmet  50 . Preferably, the infrared light impinges on only a small area, such as approximately 100 mm 2  or less. The infrared light reflects from the surface  50 ,  56  and is detected by the infrared detector  124 . 
     Preferably, through use of the adjustment pot  126 , the infrared detector  124  is sufficiently sensitive to be able to detect the reflected infrared light from a range of approximately 76.2 mm (3 inches) from the reflective surface  50 ,  56  to the infrared detector  124 . Therefore, when the night vision device  100  is in the use position, the infrared detector  124  easily picks up the infrared light, allowing the intensifier tubes  104  to be powered up. 
     When the night vision device  100  is pivoted about the pivoting mount  42  to the stowed position, as shown in  FIG. 2 , the infrared light emitted from the infrared emitter  122  does not impinge upon any surface, resulting in the infrared light not being detected by the infrared detector  124 . Since the infrared detector  124  does not detect the infrared light signal, the intensifier tubes  104  will not power up. Since the intensifier tubes  104  are not powered up, the distinctive green glow will not be emitted from the intensifier tubes  104 . 
     If the night vision device  100  is in the use position and is powered up, and then is moved to the stowed position, the infrared signal will drop below an operational threshold. If the infrared signal drops below that threshold for a predetermined period of time, such as about 0.1 second, the intensifier tubes  104  turn off. If the device  100  is then moved back to the use position, the infrared detector  124  will reacquire the infrared signal as the infrared signal reflects from the user&#39;s forehead  56  or the helmet  50  to the infrared detector  124 , allowing the intensifier tubes  104  to turn back on. Preferably, the time from reacquisition of the infrared signal to full power up of the intensifier tubes  104  is about 0.1 second. 
     In an alternate embodiment, shown in  FIG. 5 , a night vision device  200  is mounted on a rifle  210 . While the night vision device  100  is shown as binoculars, the night vision device  200  shown in  FIG. 5  is shown as a monocular scope. Further, while the night vision device  200  is shown mounted on the rifle  210 , those skilled in the art will recognize that the night vision device  200  may be mounted on a handgun, a rocket launcher, or any other suitable firearm. 
     The night vision device  200  includes a proximity sensor  220  that operates in the same manner as proximity sensor  120  on the night vision device  100  described above, except that, instead of moving the night vision device  100  toward the user&#39;s face by pivoting the night vision device  100  about a support structure to activate the proximity sensor  120 , to activate the night vision device  200 , the user moves the rifle  210  and the night vision device  200  up to the user&#39;s face to activate the proximity sensor  220 . 
     While the night vision device  100  is described as being used with the helmet  52  and the night vision device  200  is described as being used with the rifle  210 , those skilled in the art will recognize that the night vision device  100  may alternately be used in other environments, such as mounted in an aircraft cockpit, or hand-held, without departing from the scope of the present invention. 
     Additionally, while proximity sensors  120 ,  220  are shown and described as infrared detectors, those skilled in the art will recognize that other types of detectors, such as ultrasonic, microwave, radio wave, millimeter wave, terahertz wave, and ultraviolet wave detectors, may be used in place of the infrared detector. 
     Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.