Abstract:
A battery adapter system and night-vision scope using same is disclosed. The system includes a housing having a body portion and a reversible cap adapted to screw on and off of the body portion. The body portion has an interior sized to accommodate the whole of a relatively short and wide 3-volt lithium battery or to partially accommodate the narrower, taller 1.5-volt AA battery. The reversible cap has an open end and an interior, and has outer threads that allow the cap to screw to the body portion in either of two orientations. When using the lithium battery, the cap is screwed onto the body portion in a first orientation that forms a first sealed housing interior that does not include the cap interior. When using the AA battery, the cap is screwed onto the body portion in a second orientation wherein the cap open end is first placed over the portion of the AA battery that protrudes from the body portion. This forms a second sealed housing interior that includes the cap interior. Interrupted outer threads facilitate the gripping of the cap when screwing and unscrewing it from the body portion. The housing is designed to provide an electrical connection between the battery housed therein and a voltage regulating circuit adapted to provide a 3 volt DC output for an input voltage anywhere between 0.6 VDC and 3 VDC. The output voltage powers an image intensifier device connected to the circuit.

Description:
FIELD OF THE INVENTION 
   The present invention relates generally to battery adapters, and in particular, a battery adapter system for a night-vision scope, and a night-vision scope that uses the battery adapter system. 
   BACKGROUND ART 
   Night-vision scopes for rifles intensify low-level visible and/or infrared light from a dimly lit scene so that the scene is visible to the human eye. The typical night-vision scope has an image-intensifier system that consists of an optics portion and a control portion. The optics portion comprises an objective lens in optical communication with an image intensifier device that includes a photocathode. The objective lens images light (photons) from the low-light scene onto the photocathode. In response, the photocathode emits photo-electrons in proportion to the amount of light imaged at each photocathode location, thereby forming an electron pattern representative of the low-level scene image. The emitted photo-electrons are then accelerated by a first large voltage potential (e.g., 5000 volts) through a micro channel plate, which acts to multiply the number of electrons via secondary cascaded emission. The multiplied electrons move toward a phosphor screen via a second voltage potential, which converts each incident electron into a corresponding photon. The result is a visible-light pattern representative of the dimly lit scene and that is visible to the human eye. 
   The control portion of the image intensifier system includes electronic circuitry and a power source necessary for controlling and powering the image intensifier portion of the night vision system. Since night-vision scopes are portable, the power source is a battery. 
   There are three basic approaches to providing the necessary electrical power via battery to operate the image intensifier of a night-vision scope. The first is to use two AA 1.5-volt batteries in series to provide 3 volts to the electronic circuitry. The second is to use a single 3-volt lithium battery (e.g., a DL123 battery). The third is to use one AA 1.5-volt battery in conjunction with a step-up circuit, such as described in U.S. Pat. No. 6,806,683 to Saldana (the &#39;683 patent). 
   The &#39;683 patent discloses a battery adapter system that uses a battery housing in combination with a step-up circuit mounted in the battery housing. The battery adapter system allows a night-vision device to use a single AA 1.5-volt battery. The motivation behind the &#39;683 patent is that most missions where night-vision devices are used last less than 24 hours and so do not require two AA batteries. Because the single 1.5-volt battery provides the 3 volts needed, it is used up quicker than two batteries, so that the single battery is used nearly to or up to its life&#39;s end. 
   There are a number of disadvantages to the above approaches. First, the use of two AA 1.5-volt batteries in series tends to be wasteful and adds weight to the night scope. The second approach of using a single DL123 3-volt lithium battery would not be problematic were it not for the fact that prior art night scopes are adapted to use only one DL123 battery or only one or two AA batteries, but are not adapted to accommodate both types of batteries. 
   The third approach of using a single AA battery in combination with a step-up circuit according to the &#39;683 patent has several shortcomings. A first shortcoming is that the &#39;683 patent battery adapter system only accommodates one type of battery. A second shortcoming is that there is no description or teaching of how the battery adapter is integrated with a night-vision scope. A third shortcoming is that there is no description or teaching of the particularly rigorous military specifications the battery adapter system must meet if it is to be used for military equipment. 
   SUMMARY OF THE INVENTION 
   One aspect of the invention is a battery adapter system that allows first and second batteries having different sizes and different voltage outputs to power an image-intensifier device for a night-vision scope. The system includes a housing that has a body portion adapted to axially accommodate through an open end either the entire first battery or a portion of the taller, thinner second battery. The housing also includes a reversible cap with a closed end, an open end, and an interior. The cap is adapted to threadedly attach to the body portion in two different orientations. In the first orientation, the cap and body portion form a first sealed housing interior that does not include the cap interior and that operably houses the first battery. In the second orientation, the cap and body portion form a second sealed housing interior that includes the cap interior and that operably houses the second battery. The sealed housings are preferably water-tight to a depth of 66 feet, which is conning-tower depth for a submarine. The system further includes a voltage regulating circuit electrically connected to the housing and to the image intensifier device and adapted to provide a substantially constant output voltage of 3 VDC to the image intensifier device based on an input voltage from either battery that can range from about 0.6 VDC to about 3 VDC. In an example embodiment, the first battery is a 3-volt lithium battery (e.g., a DL123 battery), and the second battery is a 1.5-volt AA battery. 
   Another aspect of the invention is a night-vision scope that uses the above-described battery adapter system to power the scope&#39;s image intensifier device. 
   Another aspect of the invention is the combination of the night-vision scope as attached to a rifle and as used, for example, in an in-line configuration with a day scope. 
   Another aspect of the invention is a method of powering an image intensifier device for a night-vision scope using either of two different sized batteries having different voltage outputs, such as a 3-volt lithium battery or a taller, thinner 1.5-volt AA battery. The method includes housing either battery in a battery housing that includes a body portion adapted to axially accommodate through an open end either the entire lithium battery or a portion of the taller, thinner AA battery, so that an upper portion of the AA battery protrudes from the body portion open end. The method also includes providing a reversible cap having an opening at one end and an interior. The cap includes outer threads that allow the cap to threadedly attach to the body portion in either of first and second orientations, depending on the particular battery used. When using the lithium battery, the method includes inserting the battery into the body portion and attaching the reversible cap to the body portion open end in the first orientation to form a first sealed housing interior that does not include the cap interior and that firmly holds the battery while providing electrical contact between the battery and voltage regulating circuit. When using the thinner, taller battery, the method includes inserting the second battery into the body portion and covering the exposed end of the battery with the cap so that the exposed end fits into the cap interior. The method then includes attaching the reversible cap to the body portion open end in the second orientation to form a second sealed housing interior that includes the cap interior and that firmly holds the second battery while providing electrical contact between the battery and the voltage regulating circuit. The method further includes, for either battery, regulating an input voltage from either of the first or second batteries that ranges from 0.6 VDC to 3 VDC to form an output voltage of 3 VDC using the voltage regulating circuit. The method also includes providing the 3 VDC output voltage to the image intensifier device. 
   The first and second sealed housings are preferably formed to be water-tight to a depth of 66 ft, and also preferably are preferably formed to hold their respective batteries firmly enough to prevent rifle shock from interrupting the electrical contact between the particular battery and the voltage regulating circuit. 
   Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description which follows, the claims, as well as the appended drawings. 
   It is to be understood that both the foregoing general description and the following detailed description present embodiments of the invention are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the invention, and together with the description serve to explain the principles and operations of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side view of a rifle that includes a day scope and a night-vision scope according to the present invention; 
       FIG. 2  is a schematic block diagram showing the basic components of the night-vision scope of the present invention; 
       FIG. 3  is a close-up perspective view of an example embodiment of the reversible cap that makes up part of the battery housing; 
       FIG. 4  is a close-up cross-sectional diagram of the reversible cap of  FIG. 3  taken along the line  4 - 4 ; 
       FIG. 5  is a close-up cross-sectional view of an example embodiment of the body portion of the battery housing; 
       FIG. 6  is a perspective partially exploded view of the night-vision scope of the present invention, showing an AA battery being housed in the battery housing with the reversible cap in the AA orientation; 
       FIG. 7  is a close-up cross-sectional view of the battery housing of the night-vision scope of  FIG. 6 , with the reversible cap oriented in the AA position, and with an AA battery housed within the housing interior; 
       FIG. 8  is a perspective partially exploded view of the night-vision scope of the present invention, showing a lithium battery being housed in the battery housing with the reversible cap in the L orientation; 
       FIG. 9  is a close-up cross-sectional view of the battery housing of the night-vision scope of  FIG. 8 , with the reversible cap in the L-orientation, and with a lithium battery housed within the housing interior; and 
       FIG. 10  is a schematic diagram of an example embodiment of the battery adapter system of the present invention, showing details of an example embodiment of the voltage-regulation circuit of the present invention; 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The present invention is directed to a battery adapter system for a night-vision scope, and to a night-vision scope that uses the battery adapter system. An example night-vision scope to which the present invention is applicable is described in U.S. Pat. No. 7,142,357 to Greenslade, which patent is incorporated by reference herein. 
   In the discussion below, “volts DC” is abbreviated “VDC.” 
   General Description of the Night-Vision Scope and Battery Adapter System 
     FIG. 1  is a schematic side view of a night-vision scope  10  according to the present invention. Night-vision scope  10  includes a body  12 . Night-vision scope  10  is shown in  FIG. 1  as mounted on a quick-disconnect rail portion  20  of a rifle  22  using a quick-disconnect mount  26 . Rifle  22  also includes a day scope  30  mounted to the rifle in-line and behind night-vision scope  10 , as shown. 
     FIG. 2  is a schematic block diagram showing the basic components of night-vision scope  10 . With reference to  FIGS. 1 and 2 , night-vision scope  10  includes a lens assembly  40  in optical communication with an image-intensifier assembly  50  that includes an image-intensifier device  52 . Image-intensifier assembly  50  is arranged to receive and intensify light  56  collected by the lens assembly and imaged thereby onto image-intensifier device  52  that is housed in a housing  58 . Night-vision scope  10  includes a cylindrical battery housing  60  that includes a body portion  62  and a reversible cap  70 . Battery housing  60  is electrically connected to a voltage-regulating circuit  90 , which in turn is electrically connected to image-intensifier device  52 . Battery housing  60  and voltage-regulating circuit  90  constitute a battery adapter system  96  for night-vision scope  10 . In an example embodiment, voltage-regulating circuit  90  is located in housing  58  along with image-intensifier device  52 . 
   As discussed in greater detail below, reversible cap  70  is adapted to threadedly connect with (i.e., screw into) the open end of the body portion in either of two orientations, with both orientations establishing electrical contact between the cap and body portion so as to complete the voltage regulating circuit (housing  60  is grounded to night-vision scope body  12 ). The two possible orientations of reversible cap  70  define two different but generally cylindrical sealed housing interiors designed to respectively operatively accommodate either a relatively tall, thin standard AA battery or a shorter, wider standard lithium battery (e.g., a DL123 battery) to power the image-intensifier assembly  50  (and in particular image intensifier device  52  therein) via voltage-regulating circuit  90 . For the sake of description, the orientation of reversible cap  70  used to house an AA battery is called the “AA orientation,” while the reverse orientation used to house a lithium battery is called the “L orientation.” 
   Reversible Cap 
     FIG. 3  is a close-up perspective view of an example embodiment of reversible cap  70 , and  FIG. 4  is a close-up cross-sectional diagram of the reversible cap of  FIG. 4  taken along the line  4 - 4 . Reversible cap  70  is shown in  FIGS. 3 and 4  in the AA orientation (open end down) for the sake of illustration. Reversible cap  70  has a cylindrical sidewall  100  having a central axis A C , an inner surface  102 , and an outer surface  104 . Reversible cap  70  also has an open end  110  and an opposite closed end  112  closed by an end wall  120  having an inner surface  122  and an outer surface  124 . Inner surfaces  102  and  122  define an open-ended cap interior  130  sized to closely accommodate the end portion of a standard AA battery. 
   Sidewall outer surface  104  includes centrally located outer threads  150 . In an example embodiment, outer threads  150  are interrupted and include, for example, one or more horizontal gaps  154  and/or one or more vertical gaps  156 . Sidewall outer surface  104  also includes a first smooth portion  160  that runs around the perimeter of the sidewall between closed-end  112  and outer threads  150 . Likewise, the sidewall outer surface includes a second smooth portion  166  that runs around the perimeter of the sidewall between open end  110  and outer threads  150 . 
   End wall  120  includes an inner contact  180  located on end wall inner surface  122  that protrudes into cap interior  130  and that serves as a first electrical contact, as explained below. End wall  120  also includes an outer contact  184  located on end wall outer surface  124  and opposite inner contact  180  and that protrudes outwardly from the outer surface and that serves as a second electrical contact, as explained below. 
   Body Portion 
     FIG. 5  is a close-up cross-sectional view of an example embodiment of body portion  62 . Body portion  62  includes a cylindrical sidewall  210  having a central axis A BP , an inner surface  212 , an outer surface  214 , an open end  216  and a closed bottom end  218  closed with bottom wall  226  having an inner surface  228 . Sidewall inner surface  212  and bottom wall inner surface  228  define a body portion interior  234 . Body portion interior  234  is sized to closely accommodate a standard lithium battery. 
   In a preferred embodiment, body portion includes an upper conducting part (“upper body portion”)  62 A and a lower insulating (i.e., non-conducting) part (“lower body portion”)  62 B in sealed contact with the upper body portion (e.g., via a room-temperature vulcanizing (RTV) sealant). In an example embodiment, upper body portion  62 A is made of metal and is used as a path to ground. In an example embodiment, lower body portion  62 B is made of a temperature-resistant plastic such as DELRIN (a trademark of DUPONT Corporation), which is a durable acetal resin engineered plastic. Another suitable material for lower body portion  62 B is acrylonitrile butadiene styrene (ABS). 
   Body portion  62  includes a positive electrical contact unit  240  fixed to or formed on bottom wall inner surface  228 . Positive electrical contact unit  240  includes, for example, a contact element  242  electrically connected to a contact printed circuit board (PCB)  244 . Contact PCB includes a wire  245  that passes through a sealed feed-through  246  in lower body portion  62 B. Wire  245  leads to voltage-regulating circuit  90 , as discussed in greater detail below. An example embodiment for positive electrical contact element  242  is a PCB spring. 
   Body portion  62  also includes a set of inner threads  250  that run around sidewall inner surface  212  at sidewall open end  216 . Inner threads  250  are formed so as to threadedly engage cap threads  150 . Located immediately below inner threads  250  is a groove  260  that runs around sidewall inner surface  212 . Groove  260  is sized to accommodate an O-ring seal  266 . 
   Battery Housing with Cap in AA Orientation 
     FIG. 6  is a perspective partially exploded view of night-vision scope  10 , showing an AA battery  80 AA being housed in battery housing  60  with reversible cap  70  in the AA orientation. Battery  80 AA includes a central axis A AA , a positive end  81 AA having a positive contact  82 AA, and a negative end  83 AA having a negative contact  84 AA. Note that AA battery  80 AA is inserted into body portion  62  positive-end first. 
     FIG. 7  is a close-up cross-sectional view of battery housing  60  with reversible cap  70  oriented in the AA position, and with an AA battery  80 AA housed within housing interior  66 A. When powering night-vision scope  10  with AA battery  80 AA, the battery is placed within body portion interior  234  with its axis A AA  co-axial with body portion axis A BP  so that the battery&#39;s positive contact  82 AA makes contact with positive electrical contact element  242  on bottom wall  228 . At this point, the battery&#39;s negative end  83 AA extends beyond the plane P of body portion open end  216 . The open end  110  of reversible cap  70  is then placed over negative end  83 AA of AA battery  80 AA so that the outer cap threads  150  engage with body portion inner threads  250 . 
   As cap  70  is screwed onto body portion  62 , O-ring seal  266  engages smooth portion  166  of outer surface  106  near cap open end  110 . When cap  70  is tightly attached to the body portion, the O-ring forms a water-tight seal with the cap at smooth surface portion  166 . In a preferred example embodiment, the water-tight seal is certified to a water depth of at least 66 feet. 
   Cap electrical contact  180  is also brought into contact with the battery&#39;s negative contact  84 AA. Cap interior portion  134  combines with body portion interior  234  to define a battery housing interior  66 AA. Housing interior  66 AA accommodates the AA battery  80 AA, with the lower portion of AA battery  80 AA housed in body portion interior  234  with some room between the battery and the inner surface  212  of cylindrical sidewall  210 . The upper portion (e.g., about 25% or greater) of AA battery  80 AA associated with negative end  83 AA is closely engaged by inner surface  102  of cap cylindrical sidewall  100 . This firmly holds AA battery  80 AA within battery housing  60  even in the presence of rifle shock so that battery electrical contact is maintained with voltage regulating circuit  90 . Night-scope  10  is thus able to be powered by an AA battery  80 AA that outputs 1.5 volts, even under extreme operating conditions. 
   Note that horizontal gaps  154  and/or vertical gaps  156  in outer threads  150  of cap  70  (see also  FIG. 1 ) form interrupted threads that facilitate gripping the cap when screwing it onto or unscrewing it from body portion  62 . This is an important advantage of the present invention, given that a person using rifle  22  may be wearing gloves when they need to remove and/or insert a battery into the battery housing. 
   Battery Housing with Cap in L-Orientation 
     FIG. 8  is a perspective partially exploded view of night-vision scope  10  similar to  FIG. 6 , but showing a lithium battery  80 L being housed in battery housing  60  with reversible cap  70  in the L orientation. Battery  80 L includes a central axis A L , a positive end  81 L having a positive contact  82 L and a negative end  83 L having a negative contact  84 L.  FIG. 9  is a close-up cross-sectional view of battery housing  60  similar to  FIG. 7 , but with reversible cap  70  in the L-orientation, and with lithium battery  80 L housed within housing interior  66 L positive-side down. 
   When powering night-vision scope  10  with a lithium battery  80 L, the lithium battery is placed within body portion interior  234  with its central axis A L  co-axial with body portion axis A BP  so that the positive battery contact  82 L makes contact with positive battery contact element  242 . At this point, the negative end  83 L of lithium battery  80 L resides below the plane P defined by open end  216  of body portion  62 . The closed end  112  of reversible cap  70  is then inserted into open end  216  of body portion  62  so that the cap threads  150  engage with the body portion threads  250 . As cap  70  is screwed onto body portion  62 , O-ring seal  266  engages smooth portion  160  of outer surface  106  near cap closed end  112 . When cap  70  is tightly attached to the body portion, the O-ring forms a water-tight seal with the cap. In a preferred example embodiment, the water-tight seal is certified to a water depth of at least 66 feet. 
   Cap exterior contact  184  is also brought into contact with negative battery contact  180  when cap  70  is tightened. When in its fully engaged position, cap  70  protrudes into body portion interior  234  to define a battery housing interior  66 L smaller than the body portion interior and that closely accommodates lithium battery  80 L all around. This arrangement firmly holds battery  80 L within battery housing  60  even in the presence of rifle shock so that battery electrical contact is maintained with voltage regulating circuit  90 . Night-vision scope  10  is thus ready to be powered by a 3-volt lithium battery  80 L even under extreme operating conditions. 
   As with the case of the AA-cap orientation, in an example embodiment the L-cap orientation provides user access interrupted outer threads  150  to facilitate the gripping of cap  70  when screwing it into or unscrewing it from body portion  62 . 
   Voltage Regulating Circuit 
     FIG. 10  is a schematic circuit diagram of an example embodiment of voltage regulating circuit  90 . As discussed above, in an example embodiment, voltage regulating circuit  90  is located in housing  58  of night-vision scope  10  and is electrically connected to the battery held in battery housing  60  via wire  245  and to image intensifier device  52 . Voltage regulating circuit  90  provides a regulated, stable voltage source of 3 VDC at 20 milliamperes for optimum performance. Voltage regulating circuit  90  converts a battery voltage V B  within the range of 0.6 to 3 VDC to a regulated, stable output voltage V O  of 3 VDC, which is provided to image-intensifier device  52 . The circuit is completed by returning to the grounded housing  60  (conducting upper body portion  62 A). 
   Voltage regulating circuit  90  allows the night-vision scope to be operated with either the single AA battery  80 AA that provides 1.5 VDC when fully charged, or the single lithium battery  80 L that outputs 3 VDC when fully charged. Equally important, the night-vision scope can be operated with substantially less voltage when either of these batteries is weak from use. This also allows the night-vision scope to be made smaller while also having an acceptable running time with no degradation in night-vision scope performance right up to the battery&#39;s useful life. Also, for the standard two-battery unit, battery life is greatly extended (by 4 times). This is because the individual AA or lithium batteries can go from 1.5 VDC (when new) to 0.6 VDC (when drained), which is well beyond the standard end-of-life of 1.1 VDC, with the circuit still providing an output voltage V O  of 3 VDC. 
   Voltage regulating circuit  90  preferably uses a commercially available integrated circuit Q 1 . The circuit “charges” an inductor L 1  (e.g., 22 mH) from the external battery  80 AA or  80 L with a current flow of about 0.5 amperes and then “discharges” the inductor into the load circuit (i.e. image intensifier device  52 ). When an inductor is rapidly discharged (i.e. when it is disconnected from its current source), the voltage across it rises due to the collapsing magnetic field around the inductor. This tends to keep the current flowing. This voltage appears at output pin P 10  of Q 1  and is filtered/smoothed by capacitors C 3  and C 4 . 
   Transistor switches (not shown) inside Q 1  automatically perform the connecting of L 1 , first to the external battery, and then to the load circuit. Q 1  constantly measures the output voltage by looking at the junction of R 2  and R 3  via pin P 1  (labeled “FB” for “Feedback”). Resistors R 2  and R 3  form a voltage divider that outputs 1.3 VDC to Q 1  pin P 1  when pin P 10  (i.e. output) is at 3 VDC. 1.3 VDC is compared inside Q 1  with a precision 1.3 VDC reference voltage located inside Q 1 . Thus, Q 1 &#39;s internal control circuitry is able to adjust the switching cycle timing of charging and discharging L 1  in order to maintain a nearly constant output of 3 VDC. 
   An advantage of the battery adapter system of the present invention is that the voltage regulator circuit provides the image intensifier device with 3 VDC even when the particular battery being used is past its useful lifetime. As mentioned above, the voltage regulator circuit is able to provide an output voltage of 3 VDC even when the battery is only outputting a voltage of 0.6 volts. Prior art systems for powering image intensifier devices with one or more batteries require replacing the battery prior to the battery output reaching such a low output voltage. Since most missions involving night-vision scopes last 24 hours or less, the present invention allows a single fresh battery to be inserted prior to the mission and then used during the mission without the user having to switch batteries. In situations where the user needs to switch batteries, the user need only carry single batteries of either the lithium type or the AA type. The reversible cap makes switching batteries very easy, and the fact that only a single battery needs to replace another single battery also makes the battery switching operation easy to perform. 
   It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.