Abstract:
A night-vision optical device of the invention with controlled life expectancy contains a time measuring device built into the housing of the aforementioned device for measuring the accumulated time of active work of the device. In application to a night scope for a firearm, the device also contains a sensor, which is interlocked with activation of the scope and reacts on the shots produced from the firearm in general and separately on those shots produced during active work of the night-vision optics at nighttime. The aforementioned shots of both types are counted and stored in separate memory units. The night-time shots affects the life expectancy of the night-vision optics because of muzzle flashes which cause such devices as an image intensifier to work with an increased light load. The information obtained from the time measuring device and the shot counter makes it possible to timely receive a warning signal about the fact that the night optics or the entire firearm must be replaced.

Description:
FIELD OF THE INVENTION 
   The present invention relates to night vision optical devices, in particular to night-vision optical devices with controlled life expectancy. More specifically, the invention relates to night vision optical aiming devices for firearms, or the like. 
   BACKGROUND OF THE INVENTION 
   It is known that cathodes, phosphorescence screens, and luminescent devices degrade during work in vacuum, and their life expectancy depends on the accumulated time of active work, as well as on the number of ON and OFF switchings. With the lapse of the accumulated operation time performance characteristics of the aforementioned devices are worsened, and therefore these devices can be used to a predetermined limit. 
   For the night vision optical devices, such as night vision riflescopes with image intensifiers, in addition to the accumulated time of active work, the life expectation of the scope also depends on the number of so-called muzzle flashes, which occur during nighttime shooting. In fact, the accumulated number of flashes of bright light is one important criterion that determines the service life of the sight with the night-vision optics. 
   Attempts have been made to extend the service life, e.g., of night vision devices with image intensifying tubes by utilizing an adjustable variable gain. Thus U.S. Pat. No. 6,150,650 issued in 2000 to J. Bowen, et al. describes a night vision device which utilizes an image intensifier tube, wherein the image intensifier tube has a given life expectancy, the image intensifier tube being subjected to factory calibration for providing an optimum output during operation, wherein the calibration undesirably differs from tube to tube and is adjustable by variable control means coupled to the tube, whereby when one tube is substituted for another the difference in calibration causes non-optimum performance. The method includes the steps of: determining minimum and maximum gain limits associated with the optimum output of the night vision device; factory calibrating gain limiting means according to the determined minimum and maximum gain limits, wherein the gain limiting means are associated with the image intensifier tube and for limiting the variable control means; and, tethering the gain limiting means to the image intensifier tube. 
   In other words, since the gain of an image intensifier tubes supplied by the manufacturers and used in firearm aiming device changes, it is proposed to adjust the gain with reference to the changes in order to maintain the gain at a relatively constant level. This is because some of the factory-supplied image intensifier tubes are overadjusted to an excessive gain or power and will have a shortened life time, while others are underadjusted and though will have a longer service life, will not work with a required efficiency. This means that variations in the life expectancy of the image intensifiers may occur in a very broad range. The optimization proposed in U.S. Pat. No. 6,150,650 narrows the above range. It Is understood, however, that in order to efficiently control the workability of the night vision optics, it is important to known the expected service life of the night vision optics in order to replace it in time. This is especially important for night-vision optics used in night-vision sights of a firearm, where unexpected failure of the sight under combat conditions is absolutely Intolerable. 
   It is understood that in reality the life expectancy of a night vision optics may vary in a very wide range depending on specific conditions of practical application. For example, when a night vision optics is used in an optical aiming device of a firearm that contains an image intensifier and when it is used in intensive battle conditions with frequent muzzle flashes which shorten the lifetime of the image intensifier because of a high light load, the life time of such an aiming device will be shorter than in the case of a sniper work who keeps the night vision optics in the ON condition over a long time but without flashes and under a low light load. In other words, the life expectation of la night vision device with cathodes, fluorescent screens, and similar items operating in vacuum will depends, among other things, on two main factors: the accumulated time of actual operation (SWITCHED-ON condition) of the night vision optics and the number of muzzle flashes when the optics operates with a very high light load. 
   As far as a firearm is concerned, It is understood that with the lapse of time any weapon loses Its initial performance characteristics. Although the weapon is subject to damages caused by natural causes such as corrosion, loosening of fasteners, creeping and ageing deformation of the materials, or the like, these changes are normally revealed after such long period of time when the weapon becomes practically obsolete and is replaced by several new generations. On the other hand, when the weapon is frequently used for its direct purpose, i.e., for shooting, the process of weapon degradation is accelerated with a factor of several thousand. This is because shooting is accompanied by friction and wear, e.g., on the inner surface of the weapon barrel. Therefore, attempts have been made to limits the service life of a weapon by counting the number of shots. For example, U.S. Pat. No. 5,918,304 issued in 1999 to Karl Gartz describes an apparatus for monitoring the firing stress of a weapon barrel. It is stated that the barrels of particularly large-caliber weapons have to be replaced for safety reasons after firing a predetermined number of rounds. For this purpose a “barrel log” must be maintained in which the number of rounds fired from the barrel and the respective charge type (if different charges are used for the barrel) have to be entered. The invention is essentially based on the principle to measure, with a suitable sensor, the actual body sound signals (body oscillations) obtained upon the firing of the weapon and to compare the signals in an electronic evaluating apparatus with reference signals which characterize the different charges and which are stored in a memory. The charge value which is associated with the actual signal value and which is obtained from such a comparison is subsequently stored in a non-volatile memory of the evaluating apparatus and is added to an already stored charge value. The same applies to the number of shots measured by the sensor. The accumulated firing stress may be automatically and very accurately determined and may be at any time retrieved from the memory (electronic barrel log). Further, the apparatus may serve as a counter of fired rounds. Also, the apparatus may be utilized for determining the barrel condition because a change of the barrel condition leads to a characteristic change of the frequency spectrum of the measuring signal. 
   For the modern weapon, which is equipped with various optical and electronic devices, this problem is especially aggravated, but the weapons which are most of all sensitive to impacts resulting from the shots and recoil forces are those which are equipped with electro-vacuum devices such as image intensifiers, some distance ranges, night-vision optics, etc. In other words, for firearms used in combination with night-vision optics or similar devices that utilize vacuum electronic units with cathodes, phosphorescence screens or the like, the life expectation of the firearm is determined not only by the number of shots, wear, or mechanical damage but also by the service life of the aforementioned optical devices which is normally limited to several thousand hours of active work and, as has been mentioned above, to a great extent depends on the number of muzzle flashes acting-on cathodes, phosphorescence screens, luminescent devices, or similar elements of vacuum night vision optics. 
   However, none of the existing prior-art devices known to the applicant are used for controlling or diagnosing the life expectation of the night vision instruments with reference to three aforementioned factors (number of shots, active time of operation of the night vision optics, and number of muzzle flashes during the use of the night vision optics) and their relationship. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a three-dimensional view of the optical sight of the invention installed on a rifle. 
       FIG. 2  is a longitudinal sectional view of the night-vision sight of the invention. 
       FIG. 3  is a block diagram of an electric circuit of the measuring and counting system used in the night-vision system of the invention. 
       FIG. 4  is a block diagram similar to the one shown in  FIG. 3  for an embodiment in which reading of data from the respective data processing units is carried not via a remote control system but via direct electric connection of the data processing units to a data-reading unit via a connector. 
   

   OBJECTS AND SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a night-vision optical device having a controlled life expectancy. It is another object to provide a night vision optical device of the aforementioned type, which accumulates information relating to the time of active work of the device. It is another object to provide a night-vision optical aiming device for a firearm, which accumulates information relating to the total number of shots produced from the firearm. It is another object to provide a night vision optical aiming device of the aforementioned type, which accumulates information relating to the number of shots counted in parallel with measuring the time of active work of the night-vision optical aiming device. It is another object to provide a night-vision optical aiming device of aforementioned type which has a shot counter in combination with a unit that generates a signal indicating that the night-vision optics or the entire firearm has to be replaced. It is It is another object to provide a night vision optical aiming device of the aforementioned type, in, which the time and shot number information is stored and can be retrieved and displayed on the optical device or in a remote location. 
   A night-vision optical device of the invention with controlled life expectancy contains a time measuring device built into the housing of the aforementioned device for measuring the accumulated time of active work of the device. In application to a night scope for a firearm, the device also contains a sensor, which is interlocked with activation of the scope and reacts on the shots produced from the firearm in general and separately on those shots produced during active work of the night-vision optics at nighttime. The aforementioned shots of both types are counted and stored in separate memory units. The night-time shots affects the life expectancy of the night-vision optics because of muzzle flashes which cause such devices as an Image intensifier to work with an increased light load. The information obtained from the time measuring device and the shot counter makes it possible to timely receive a warning signal about the fact that the night optics or the entire firearm must be replaced. 
   DETAILED DESCRIPTION OF THE INVENTION 
   One practical embodiment of the invention will be described below with reference to a night-vision optical aiming device. It is understood that this can be a night-vision optical device of any type and that the application to a riflescope described below should be considered only as an example. 
     FIG. 1  is a general three-dimensional view of a firearm  20  equipped with a night-vision aiming device  22  of the invention attached in a known manner to the firearm  20 , e.g., with a one-piece plate  24  of the firearm and the mounting bracket  26  of the night-vision aiming device  22  which are connected, e.g., via a dovetail arrangement  28 . It is understood that the type of connection is beyond the scope of the present invention. Such a device may be represented, e.g., by a night-vision sight of ARIES MK-6600 type produced by American Technology Network Corporation, So. San Francisco, Calif. USA. 
   Reference numeral  30  designates the ON/OFF button of the night-vision aiming device. Reference numeral  32  designates a socket for a connector (not shown) that can connect the measuring units (described in detail below) of the night-vision aiming device  22  with a remote data reading system (not shown in FIG.  1 ). 
   A more detailed longitudinal sectional view of the aforementioned night-vision sight of the invention is shown in FIG.  2 . It can be seen that a standard night-vision sight  22 , e.g., the one mentioned above, has plenty of room inside the night-vision sight housing  34  for placing measuring units of the invention in one of the inner housing compartments. In the embodiment shown in  FIG. 2 , the measuring units, which are shown as-a printed circuit board (PCB)  36 , are secured to the housing  34  in a compartment  38 . Reference numeral  40  designates a clock generator, which generates time clocks counted by a clock counter  42 . Reference numeral  44  designates a signal transmitter, e.g., an infrared signal transmitter located on the outer side of the night-vision device  22  or inside the housing  34  but exposed to the outside, e.g., through an opening (not shown). 
   A block diagram of an electric circuit of the measuring and counting system used in the night-vision system of the invention is shown in FIG.  3 . As can be seen from  FIG. 3 , the clock generator  40  installed on the PCB  36  is connected to a data processing unit  46  via a clock counter  42  which counts the accumulated number of time clock signals generated by the clock generator  40 . The activation of the clock generator  40 , the clock counter, and the data processing unit  46  is interlocked with the ON/OFF button  30  of the night-vision aiming device  22  (FIG.  1 ). The data processing unit  46  is permanently connected with a nonvolatile storage memory  48 , which receives the information from the output of the data processing unit  46  and permanently stores the obtained data in the memory ready for retrieval at any time. Another output of the data processing unit  46  is connected to the aforementioned signal transmitter  44 , e.g., infrared signal transmitter ( FIGS. 1 ,  2 ,  3 ), via a driver  50 . The aforementioned elements may be mounted on the aforementioned PCB  36  (FIGS.  2  and  3 ). 
   A surface of the scope, preferably the one perpendicular to the optical axis O 1 —O 1  of the night vision riflescope  22 , e.g., an inner wall  52  of the compartment  38 , supports a shot sensor, e.g., in the form of a piezo-sensor  54 . It is understood that the wall  52  is also perpendicular to the direction of shooting. With such an arrangement of the shot sensor  54 , the recoil forces generated during shooting will be most efficiently perceived by the sensor  54 . 
   The PCB  36  also supports another data processing unit  56 , which is connected to the piezo-sensor  54  via a signal amplifier  58  and an analog/digital converter (AID converter)  60 . Reference numeral  61  designates a second clock generator, which is connected to the data processing unit  56  via a clock counter  62 . This counter is needed for proper operation of the data processing unit  56 . 
   The data processing unit is connected to two memory units, i.e., a nonvolatile memory unit  64  for registering and storing the total number of shots detected by the piezo-sensor  54  and a nonvolatile memory unit  66  for registering and storing the total number of shots produces during the active work of the night-vision aiming device  22  (FIGS.  1  and  2 ), which is energized by pushing the push-button  30 . 
   Reference numeral  68  designates a power supply battery that keeps the aforementioned second set of elements, i.e., the signal amplifier  58 , the data processing unit  56 , the clock generator  60 , the clock counter  62 , etc., energized and that supplies the power to the first set of the elements, i.e., the clock generator  40 , the clock counter  42 , the data processing unit  46 , etc., when the push button  30  is pressed. 
   The aforementioned second set of elements contains a driver  70  and may contain a second signal transmitter  72 , e.g., infrared signal transmitter located on the outer side of the night-vision device  22  or inside the housing  34  but exposed to the outside, e.g., through an opening (not shown). Reference numeral  31  ( FIG. 3 ) designates a push button, which activates retrieval of the information stored in the memory units  42 ,  64 , and  66 . 
   Those skilled in the art understand that both aforementioned sets of elements may be powered from a common power source and may share the same data processing unit. 
   A unit  74  shown on the right side of  FIG. 3  designates a remotely-located signal receiving and displaying unit, which contains a first receiver  76  for receiving signals from the signal transmitter  44  and a second receiver  78  for receiving signals from the signal transmitter  72 . The data received by the receivers  76  and  78  are transmitted to respective data processing units  80  and  82  and displayed on a display  84 . Reference numeral  86  designates a power source for supplying power to the receivers  46 ,  78 , the data processing units  80 ,  82 , and the display  84  after pressing on the push button  88 . The measured values are compared with given values or with a single reference given value that limits the life expectancy of the device for determining the remaining life-expectancy resource. 
   The transmitter-receiving system composed of the transmitters  72 ,  44  and receivers  78 ,  76  with the auxiliary devices may be implemented in different forms and may comprise standard systems, which are beyond the scope of the present invention. For example, this may be a system similar to the one used in a conventional TV remote control. 
     FIG. 4  is a block diagram similar to the one shown in  FIG. 3  for an embodiment in which reading of data from the respective data processing units is carried out not via a remote control system but via direct electric connection of the data processing units  56 ′ and  46 ′ to a data reading unit  74 ′ via a connector, e.g., a pin connector  44 ′- 72 ′. The rest of the diagram is identical to the diagram of FIG.  3 . The parts of the circuit of  FIG. 4  equivalent to those of  FIG. 3  are designated by the same reference numerals with an addition of a prime, e.g., the piezo-sensor  54  of  FIG. 3  will correspond to a piezo-sensor  54 ′ of  FIG. 4 , etc. Therefore the description of the remaining elements of the diagram of  FIG. 4  is omitted. It is understood that the display  84 ′ may be installed on the riflescope  20 . 
   The night-vision riflescope  20  of the aforementioned embodiment operates as follows. 
   The power supply battery  68  always keeps the second set of elements, i.e., the signal amplifier  58 , the data processing unit  56 , the clock generator  60 , the clock counter  62 , etc., energized, so that whenever a shot is produced from the rifle  20 , the recoil of the firearm  20  resulting from the shot will be registered by the piezo-sensor  54 , and the accumulated number of the shots produced from the firearm  20  will be counted by the central processing unit  56  and stored in the nonvolatile memory unit  66  for retrieval on demand. 
   When the pushbutton  30  is pushed on, the power supply battery  68  energizes the first set of the elements, i.e., the clock generator  40 , the clock counter  42 , the data processing unit  46 , etc. As a result, a night-vision riflescope is activated, and the time of its active work, i.e., the time during which it is switched on, is measured and added to the previously accumulated total time of the active work which is stored in the nonvolatile memory unit  48 . At the same time, the data processing unit  46  of the first set of the elements sends a command to the data processing unit  56  of the second set of the elements for separately counting and storing in the nonvolatile memory unit  64  the number of shots produced from the firearm irrespective of the operation of the night vision system and in the nonvolatile memory unit  66  the number of shots produced during the working time of the night vision system (i.e., with muzzle flashes that can affect the light-sensitive elements of the night vision system). 
   When it is necessary to display the information about the total number of shots, the accumulated time of active work of the night vision system, and about the number of shots produced during operation of the night-vision with the damaging effect of the muzzle flashes, first the push button  88  of the data receiving unit  74  is pushed on for activating the elements of this unit. Then data processing units  56  and  46  are activated by pushing on the button  31  ( FIG. 3 ) for retrieving the aforementioned information from the respective memory units  64 ,  66  and  48  and for transmitting the retrieved data via the transmitters  72  and  44  to the receivers  78  and  76  remotely ( FIG. 3 ) or directly from the data processing units  56 ′ and  46 ′ via the connector  44 ′ to the receiving unit  74 ′ (FIG.  4 ). 
   Thus it has been shown that the present invention provides a night-vision optical device having a controlled life expectancy, which accumulates information about the time of active work of the device, the total number of shots produced from the firearm, and the number of shots produced only during active work of the night vision system with muzzle flashes that affect the life time of such elements as cathodes, phosphorescence screens, and luminescent devices which degrade under the effect of light. 
   The invention has been shown and described with reference to specific embodiments, which should be construed only as examples and do not limit the scope of practical applications of the invention. Therefore any changes and modifications in technological processes, constructions, materials, shapes, and their components are possible, provided these changes do not depart from the scope of the attached patent claims. For example, in addition to a riflescope, the night vision optical device may comprise night vision binoculars, monoculars, goggles, etc. The diagrams of  FIGS. 3 and 4  can be accomplished with different arrangements and types of their components. For example, a single CPU may control operation of the elements of both sets, and the receiver-transmitter system may comprise a standard commercially produced transceiver. The night vision optical device may contain a selector connected to an alarm unit, which will produce a warning signal when the selected values of one, two, or all three aforementioned parameters or a certain parameter that expresses relationship between them is reached.