Abstract:
Reticles and scopes using reticles are provided with increased visibility in low-light conditions by illuminating the reticle using the light emitted by a quantity of photoluminescent material. The photoluminescent material may be placed on the reticle itself or emit light which is cast onto the reticle. In some forms, the reticle is entirely coated with the photoluminescent material and in other forms, the photoluminescent material is selectively deposited on a portion of the reticle or an area adjacent the reticle. In other forms, the photoluminescent material is located remote from the reticle and the light emitted from the reticle is transmitted to the reticle. Alternatively, the light may be transmitted directly into a disc of optical material which has an area etched into a reticle pattern whereby the transmitted light escapes from the disc through the etched out portion and provides an illuminated reticle pattern which is visible in low light conditions.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention is concerned with the use of scopes in low-light conditions. More particularly, scopes in accordance with the present invention utilize a reticle to aid in range-finding and aiming of the scope or an object attached to the scope. Still more particularly, the present invention concerns illuminating the reticle such that the scope maybe utilized in low-light conditions without sacrificing the utility of the reticle. Even more particularly, the present invention involves the use of photoluminescent material to aid in the illumination of the reticle. The photoluminescent material may be deposited directly on the reticle or in an area adjacent the reticle such that ambient light from the photoluminescent material illuminates the reticle. When deposited directly on the reticle, the photoluminescent material may be found on only a portion of the reticle as an enhanced sighting marker such as the center of a cross-hair or may be used on the entire reticle.  
           [0003]    2. Description of the Prior Art  
           [0004]    Scopes utilizing reticles as sighting markers have been in use for many years. Because the reticle is located within the housing of the scope, the usefulness of prior art reticles is decreased in low-light conditions. This loss of utility is a result of the lack of light illuminating the reticle and making it visible to the person looking through the scope. Such a deficiency makes the aiming of scopes more difficult in low-light conditions as the reticle as a sighting marker cannot be differentiated from the object being observed through the scope. In the case of hunters using riflescopes having reticles, this problem makes hunting in low-light conditions difficult due to the lack of precision resulting from a reticle which is undifferentiated from the hunted animal and surrounding background.  
           [0005]    There have been many attempts to overcome this problem but all solutions of the prior art suffer various deficiencies. For example, U.S. Pat. No. 4,627,171, to Dudney provides a cross-hair illuminator which uses a lamp powered by a battery which transmits light through a fiber optic cable onto the reticle. Such a solution requires the use of batteries which suffer from dramatically reduced output and life in low temperature conditions. Furthermore, the battery may become exhausted prior to the end of the a hunt, thereby requiring either replacement of the battery during which time potential sighted objects may move out of range, or loss of the advantage provided by an illuminated reticle. Another example is provided by U.S. Pat. No. 5,456,035 to Stiles which illuminates the reticle using a chemically illuminated reticle sight. Light from a chemical illumination device is used to create a reticle image which is highly visible in low-light conditions. Such an invention suffers from the short life of the light produced by the chemicals. As a result, replacement chemicals must be available for use in case the light fades or disappears. Another solution to this problem has been the incorporation of radioactive materials to illuminate the reticle. Such a solution obviously requires special handling techniques and presents difficult manufacturing problems. Other solutions to this problem include using illumination sources which either illuminate the sighted object or illuminate an area around the scope. Each of these solutions is undesirable in that either the sighted object becomes aware of the illuminated area or the hunter&#39;s position is given away by the light, thereby reducing the possibility of approaching the sighted object without being detected.  
           [0006]    Accordingly, what is needed is an illuminated reticle which does not require electrical current or light sources which need to be replaced. What is further needed is an illuminated reticle which does not illuminate the sighted object or an area around the scope.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention overcomes the problems outlined above and provides a unique advance in the state of the art. Briefly, the present invention utilizes photoluminescent material to illuminate a reticle such that the scope containing the reticle can be used in low-light conditions. Using photoluminescent material is advantageous over other methods of illuminating reticles in that photoluminescent material does not need to be replaced in order to become recharged, does not require electrical current, does not illuminate the sighted object, and does not illuminate an area around the scope. By having an illuminated reticle, animals or objects which are active in the early morning or the late evening are more visible and the user of such a scope will be able to focus their vision more quickly and accurately than was heretofore possible.  
           [0008]    In one aspect of the present invention, a quantity of photoluminescent material is deposited on the reticle. The photoluminescent material may be deposited on only a portion of the reticle or it may substantially cover the reticle. The photoluminescent material may be in granular form, in a paint or dye, incorporated in tape, or any combination of these forms. It is preferred that the particle size of the photoluminescent material be less than about 30 μm. Such a small particle size permits the photoluminescent material to have sharply defined edges when incorporated into a paint or dye. More preferably, the particle size is between about 2 μm and 20 μm. Still more preferably, the average particle size is between about 5 μm and 10 μm.  
           [0009]    When the photoluminescent material is deposited on the reticle, the light emitted from the material illuminates the reticle so that it can be seen and used in low-light situations. Depositing the photoluminescent material can be accomplished using many different conventional methods including dipping, airbrushing, standard paint brushing, powder coating, vacuum deposition, sputtering, gluing, various photolithographic processes, and combinations of all of these methods. The material deposited on the reticle may be in any shape or may be directly incorporated into reticle or even used as the reticle itself. When not used as the reticle, the photoluminescent material may be deposited on any portion of the reticle or in an area adjacent the reticle which does not interfere with the view through the scope but which still allows light emitted from the material to illuminate the reticle. For example, the photoluminescent material may be placed in sufficient quantity around the edge of the reticle and the light emitted illuminates the reticle. Alternatively, the photoluminescent material may be used as an enhanced sighting marker by being deposited on a portion of the reticle. For example, in a conventional cross-hair sighting marker, any portion of the cross-hairs may comprise photoluminescent material which will illuminate the reticle. For example, the reticle may comprise a conventional cross-hair pattern and the center of the cross hair may comprise or have photoluminescent material deposited thereon, thereby providing an enhanced sighting marker on the reticle. Thus, the reticle may comprise a first line intersected by a second line and oriented such that the first line is perpendicular to the second line and any portion of these lines may include photoluminescent material. Such is also true for the circumscribing ring which is commonly used to encircle the crosshair region of a reticle. Alternatively, the photoluminescent portion may comprise a dot of photoluminescent material on the reticle.  
           [0010]    In some forms, the photoluminescent material will be included as the reticle itself. For example, fine strips of photoluminescent material may be used to construct the reticle. Alternatively, when the reticle is located on another object such as a plate of optical material, the photoluminescent material may be deposited onto the reticle or comprise the reticle, as described above.  
           [0011]    In another aspect of the invention, a riflescope having enhanced utility in low light conditions is provided. Generally, the riflescope will comprise a tubular housing having an interior and an exterior and two opposed ends. One end of the housing will have an eyepiece and the other end will have an objective lens. A reticle will be located in the interior of the housing between the two opposed ends and photoluminescent material will be deposited on the interior of the housing in order to illuminate the reticle. Preferably, the photoluminescent material is located adjacent to the reticle in order to aid in its illumination. In some forms, the photoluminescent material is placed on the interior of the housing in a ring shape in order to provide the reticle with even levels of light about the entire reticle. Such a ring shape may circumscribe the interior of the housing as an uninterrupted coat of photoluminescent material or may be in the form of a broken series of lines of photoluminescent material to provide a ring comprised of dash shapes.  
           [0012]    In another aspect of the present invention, the photoluminescent material is located away from the interior of the housing of a scope, remote from the reticle, and the light emitted from the photoluminescent material is transmitted to the reticle via a light-transmitting pipe. One preferred example of a light-transmitting pipe is fiber optic cable. In this form of the invention, a scope will include a quantity of photoluminescent material on the housing of the scope and the pipe will transmit the light from the material to the interior of the scope housing wherein the light will be cast onto the reticle. Another form of this embodiment will have the light-transmitting pipe terminate adjacent the edge of a plate of optical material. Preferably, there will be two pipes leading from the photoluminescent material to the plate of optical material and these two pipes will have their light-transmitting end terminate at the edge of the plate and be oriented at 90° angles relative to each other. The plate of optical material will have an etched portion which allows light emitted from the pipe and into the plate to escape from the etched out portion of the plate and escape. The escaping light serves as an illuminated reticle and provides a reticle identical in shape to the etched out portion. Preferably, the plate of optical material will also include an anti-reflective layer and a protective layer thereon which will both be etched out during the etching process. In another embodiment using a light transmitting pipe optically connected to a quantity of photoluminescent material, the pipe is secured to the reticle and the end of the pipe which emits light is positioned on the reticle and aimed so that it serves as the illuminated reticle. That is to say, the end of the pipe emitting light is aimed toward the eyepiece end of the scope such that a user of the scope can see the emitted light and it serves as the reticle.  
           [0013]    When the photoluminescent material is located remote from the reticle, it may be contained in a receptacle located on the housing of a scope. Preferably, the receptacle will have a removable cap and in some preferred embodiments, the cap will have the photoluminescent material therein. In other forms of the invention, the photoluminescent material will be removably placed in the receptacle. Regardless of the particular structure, the photoluminescent material will be transmitted from a location remote from the reticle to a location either adjacent to or on the reticle.  
           [0014]    Scopes useful with the present invention are any scopes which utilize a reticle. Such scopes include riflescopes, telescopes, spotting scopes, binoculars, and the like. When the form of the invention using light transmitted via a light-transmitting pipe optically connected with photoluminescent is used in conjunction with rifles, the photoluminescent material may be located on the housing of the scope or may be on the rifle to which the scope is connected.  
           [0015]    In use, the photoluminescent material of the present invention is activated by exposing the material to a light source. This exposure can be either direct exposure or indirect exposure. Once the material is activated, it will emit a quantity of light for a period of time related to the amount of activation or charging. It is this emitted light which is used to illuminate reticles in scopes, thereby increasing their utility in low-light conditions. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is an illustration of a riflescope in accordance with the present invention;  
         [0017]    [0017]FIG. 2 is an illustration of a circle-x reticle having a quantity of photoluminescent material thereon;  
         [0018]    [0018]FIG. 3 is an illustration of a mil-dot reticle having a quantity of photoluminescent material thereon;  
         [0019]    [0019]FIG. 4 is an illustration of a multiplex reticle having a quantity of photoluminescent material thereon;  
         [0020]    [0020]FIG. 5 is an illustration of a low light reticle having a quantity of photoluminescent material thereon;  
         [0021]    [0021]FIG. 6 is an illustration of a low light reticle having a center dot with a quantity of photoluminescent material thereon;  
         [0022]    [0022]FIG. 7 is an illustration of a reticle inside the housing of a scope that is illuminated by a band of photoluminescent material adjacent the reticle;  
         [0023]    [0023]FIG. 8 is an illustration of a reticle inside the housing of a scope that is illuminated by a broken band of photoluminescent material adjacent the reticle;  
         [0024]    [0024]FIG. 9 is a perspective view of a reticle in a reticle housing having a layer of photoluminescent material thereon;  
         [0025]    [0025]FIG. 10 is a perspective view of a disc of optical material having an etched out reticle pattern in the center thereof and two light sources on the periphery thereof;  
         [0026]    [0026]FIG. 11 is a cross-sectional view through the center of FIG. 12 illustrating the etched out portion;  
         [0027]    [0027]FIG. 12 is a cross sectional view of the eyepiece end of a scope illustrating a quantity of photoluminescent material located remote from the reticle; and  
         [0028]    [0028]FIG. 13 is a view of a reticle having an illuminated center dot wherein the dot is illuminated by being at the end of a light transmitting pipe. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0029]    The following description sets forth preferred embodiments of the present invention. It is to be understood, however, that these embodiments are provided by way of illustration and nothing therein should be taken as a limitation upon the overall scope of the invention.  
         [0030]    Turning now to the drawing figures, FIG. 1 illustrates a riflescope  10  in accordance with the present invention. The scope  10  presents an elongated tubular housing  12  having a first end  14  and an opposed second end  16 . First end  14  terminates at eyepiece  18  which includes a first eyepiece lens  19  and a second eyepiece lens  20 . Second end  16  terminates at objective lens  22  which is also located within housing  12 . There are also three erector lenses  24 ,  26 ,  28  located within housing  12  between first end  14  and second end  16 . Reticle  30  is located within housing  12  between first end  14  and erector lens  24 . This places reticle  30  in the second focal plane of the riflescope  10 . However, reticle  30  may also be located in the first focal plane (between lens  26  and  22 ) either alone or together with another reticle in the second focal plane. Located on housing  12  are covers for the windage adjusting screw  32  and the elevation adjusting screw  34 .  
         [0031]    In accordance with the present invention, reticle  30  will comprise a quantity of photoluminescent material on cross-hairs  36 ,  38 , thereby providing an illuminated reticle which will provide greater utility under low light conditions. This photoluminescent material may be located at any position on either cross-hair  36 ,  38 . Alternatively, either one or both cross-hairs may have photoluminescent material deposited thereon or the intersection  40  of the cross-hairs  36 ,  38  may be the only point at which there is photoluminescent material.  
         [0032]    FIGS.  2 - 6  illustrate some of the potential reticle embodiments that are possible with the present invention. As shown by the wide variety of applications possible in accordance with the present invention, one of ordinary skill in the art will understand that the construction of the reticle, the orientation of the sighting markers of a reticle, and the placement of photoluminescent material on or around a reticle is a matter of choice.  
         [0033]    [0033]FIG. 2 illustrates a conventional circle-x reticle  30   a . Reticle  30   a  presents four wide band cross-hairs  42   a ,  42   b ,  42   c ,  42   d  encircled by a circumscribing ring  44 . Crosshairs  42   a ,  42   b ,  42   c ,  42   d  each present a first end  46  adjacent ring  44  and a second end  48  which terminates at interior ring  50  which circumscribes two thin band cross hairs  52 ,  54  which are oriented perpendicularly to each other. In this embodiment, ring  50  and cross-hairs  52 ,  54  have a quantity of photoluminescent material deposited thereon which illuminates the center of the reticle, thereby providing an enhanced sighting marker at the center of the reticle which is useful in low-light conditions. The photoluminescent material could be deposited on ring  50  and cross-hairs  52 ,  54  using any conventional process including painting, dipping, airbrushing, standard brushing, powder coating, vacuum deposition, sputtering, gluing, or even be used as the reticle itself. Of course, the reticle can be formed of any material which could be used as a reticle such as thin pieces of metal wire, spider webs, or even thin film alloys such as a nickel alloy. Some of these materials use a photolithographic process to etch a reticle pattern out of the material and this etched out pattern may be applied to a plate of optical material and subsequently covered with a protective coating and/or an antireflective (AR) coating. In another alternative embodiment, a thin sheet of photoluminescent material is shaped into a reticle pattern by cutting or etching and the entire reticle would then comprise photoluminescent material.  
         [0034]    [0034]FIG. 3 illustrates another reticle  30   b , commonly known as a mil-dot reticle which includes wide-band cross-hairs  42   a ,  42   b ,  42   c ,  42   d  which extend from reticle ring  44  to cross-hairs  52 ,  54 . These wide-band cross-hairs have a tapered second end  48  eventually leading to cross-hairs  52 ,  54  which have a plurality of dots  56  comprising photoluminescent material. These dots  56  aid in directing a user&#39;s eye to the center of the reticle  30   b  and the photoluminescent material increases visibility of reticle  30   b  in low-light conditions. Dots  56  may be applied or deposited to cross-hairs  52 ,  54  as described above.  
         [0035]    [0035]FIG. 4 illustrates a multiplex reticle  30   c  in accordance with the present invention. Reticle  30   c  includes circumscribing ring  44 , wide-band cross-hairs  42   a ,  42   b ,  42   c ,  42   d  which taper into thin cross-hairs  52 ,  54 . In this embodiment, ring  44  includes the photoluminescent material which emits enough light to illuminate the reticle. Typically, reticles similar to reticle  30   c  are made via conventional photolithographic processes on thin film nickel alloy. Again, the photoluminescent material may be applied or deposited to ring  44  as described above.  
         [0036]    [0036]FIG. 5 illustrates one version of a low-light reticle  30   d . This reticle includes ring  44 , wide-band cross-hairs  42   a ,  42   b ,  42   c ,  42   d , and thin cross-hairs  52 ,  54 . The first end  46  of the wide-band cross-hairs terminates in ring  44  while second end  48  includes narrow portion  58  at the end thereof. Thin cross-hairs  52 ,  54  extend from portion  58 , intersecting at the center of reticle  30   d . Photoluminescent material is applied to, deposited on, or comprises wide-band cross-hairs  42   a ,  42   b ,  42   c ,  42   d  and thin crosshairs  52 ,  54  such that both of these sighting markers emits light after being charged with either ambient light or directed light.  
         [0037]    [0037]FIG. 6 is similar to FIG. 5, however, there is a quantity of photoluminescent material at the intersection of thin cross-hairs  52 ,  54  in the form of a center dot  60 . Because the center dot  60  comprises photoluminescent material, the visibility at this center of aim is increased in low-light conditions.  
         [0038]    [0038]FIG. 7 illustrates another embodiment in accordance with the present invention wherein a cut-away version of eyepiece  18  is shown without eyepiece lenses  18 ,  19 . Eyepiece  18  includes housing  62  having an interior surface  64  and an exterior surface  66 . Reticle  30  is secured inside housing  68  and comprises first wire  70  oriented perpendicularly to second wire  72 . The interior housing surface  64  includes a circumscribing band of photoluminescent material  74  located adjacent reticle  30 . Band  74  may be deposited or applied to surface  64  as described above or may comprise a separate band of frictional material placed inside housing  62 . Moreover, band  74  may be located on either side of reticle  30  provided that the light emitted from the photoluminescent material is capable of sufficiently illuminating the reticle. Another alternative embodiment is provided in FIG. 8 which is identical to FIG. 7 with the exception of the band  74  which is contiguous in FIG. 7 but is broken or separated in the embodiment of FIG. 8. This band of material is shown as a series of spaced dash-shaped portions  74   a ,  74   b ,  74   c ,  74   d  forming a divided band circumscribing the interior of housing  62 . Of course, the portions of photoluminescent material need not be in any particular shape provided that the shape and spacing of the photoluminescent portions provide enough illumination of the reticle for increased visibility in low-light conditions.  
         [0039]    [0039]FIG. 9 illustrates a reticle  30  similar to those described for FIGS. 7 and 8. Reticle  30  has cross-hairs  76 ,  78  oriented perpendicularly to each other and secured within housing  68 . Housing  68  is in the shape of a donut having exterior surface  80  and interior surface  82 . The quantity of photoluminescent material is deposited on, or applied to interior surface  82  such that reticle  30  is illuminated by the light emitted from the photoluminescent material.  
         [0040]    [0040]FIG. 10 illustrates yet another embodiment of the present invention comprising a disc  84  of optical material having a peripheral edge  86  circumscribing disc  84 . A pair of light-transmitting pipes  88 ,  90  contact peripheral edge  86  and are located approximately 90° apart. Pipes  88 ,  90  each present a light-emitting end  92 ,  94  contacting peripheral edge  86  for emitting light into disc  84 . Preferably, pipes  88 ,  90  are aimed at etched out portion  96  which is in the shape of a cross-hair reticle. Disc  84  further presents a coating  98  on each side thereof. This coating  98  may be an antireflective coating, a protective coating or a combination thereof. Etched out portion  96  is also etched out of coating  98  on one side thereof such that a groove extends through coating  98  and a portion of disc  84 . Light transmitted through pipes  88 ,  90  is emitted from portion  96 , thereby providing a lighted reticle shape which can be used in low-light conditions. Thus, in the field of view through a scope, when light is transmitted through pipes  88 ,  90 , into disc  84  and emitted through portion  96 , the reticle shape appears as a lighted cross-hair, thereby improving its use as a sighting marker in low-light conditions.  
         [0041]    [0041]FIG. 11 illustrates a cross-sectional view through the center of FIG. 10. Etched out portion  96  is clearly shown to extend through one surface of coating  98  and into a portion of disc  84 . Pipe  90  is aimed at one of the two cross-hair lines  100 ,  102  of portion  96 . In use, disc  84  is positioned inside the housing of a scope such as the one illustrated in FIG. 12. As shown in FIGS. 10 and 11, light-transmitting pipes  88 ,  90  are optically connected to light emitted by a quantity of photoluminescent material  104 . To assist in the transmission of light from material  104 , a lens  106  is positioned to direct light from material into the light-receiving end of a light-transmitting pipe  108 . This light is transmitted through pipes  88 ,  90  and into disc  84 .  
         [0042]    [0042]FIG. 12 illustrates a cross-sectional view of an eyepiece end of a scope. Eyepiece end  110  includes rubber eyecup  112  circumscribing one end of eyepiece  110 , reticle  114  at the end opposite eyecup  112 , connected by housing  116 . Within housing  116  between reticle  114  and eyecup  112  are a plurality of lenses  118 . Reticle  114  is positioned between reticle fastener frame  120  and reticle base  122 . Light transmitting pipe  124  extends from an area adjacent reticle  114  into the interior  126  of turret  128 . Turret  128  includes cap  130  threadably received on turret base  132  and preferably includes a quantity of photoluminescent material preferably located on the interior of cap  130 . Turret interior  126  includes lens  106  which is positioned to receive emitted light from the photoluminescent material  124  on cap  130  when cap is placed onto turret  128 . Pipe  124  is sealed by grommet  134  and positioned such that light emitted from photoluminescent material  104  is directed by lens  106  toward the light receiving end  136  of pipe  124  where it is transmitted through pipe  124  until it is emitted from light emitting end  138  and projected onto reticle  114  such that reticle  114  is illuminated. To use this embodiment, cap  130  is removed from base  132  to permit light to activate photoluminescent material  104 . This removal can be done by unthreading or otherwise removing the cap  130  and exposing the material to a light source to activate the material. Once material  104  has been sufficiently activated, cap  104  is replaced onto base  132  and the light emitted by the photoluminescent material is transmitted toward the reticle through pipe  124 . In some embodiments, the light is projected onto the reticle and in others, the light is projected into the reticle such as is shown in FIG. 10 or in FIG. 13 wherein the light transmitting pipe  124  (shown enlarged for detail) is affixed to the reticle such that the light transmitting end  138  projects light at the center point of the reticle  30   e . Of course, pipe  124  can be located anywhere on the reticle  30   e  and will preferably run along one of the sighting markers such as  42   a.