Patent Publication Number: US-6216352-B1

Title: Day/night weapon sight

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of application Ser. No. 09/272,643 filed Mar. 18, 1999, now issued as U.S. Pat. No. 6,122,833 issued Sep. 28, 1999, and which is a divisional of application Ser. No. 08/780,175, filed Dec. 26, 1996, now issued as U.S. Pat. No. 5,956,854, issued Sep. 28, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     This invention relates generally to sights for hand-held weapons such as rifles, pistols and bows, and more particularly to such sights having a means for illuminating the sight in low-light and dark conditions. 
     2. History of Related Art 
     Many attempts have been made to provide a sight for guns and bows that is usable under daylight, low light, and night conditions. One attempt to provide an aiming sight usable under both day and night conditions is disclosed in U.S. Pat. No. 4,070,763 issued Jan. 31, 1978, to Stanley L. Carts, Jr. The Carts sight proposes the use of hollow light-absorbing fibers, or solid fibers having a transparent core, that are coated with a light-absorbing material, such as black glass, to keep light contained within the fiber. A small dot is observable only when the axis of the fiber is aligned within one milliradian of a line from the user&#39;s eye to the radiation source. This requirement makes the sight difficult to use because of the time that may be required to “find” the dot source and then align the weapon with the target without losing sight of the dot. 
     The use of light-gathering fluorescent fibers in a bow sight is disclosed in U.S. Pat. No. 5,442,861 issued Aug. 22, 1995, to Paul M. LoRocco, the inventor of the present invention. In his earlier invention, Mr. LoRocco discovered that the use of light-gathering fluorescent fibers dramatically increased the amount of light emitted from an end of the fiber, in both daylight and low light conditions. More recently, several arrangements for adapting light-gathering fluorescent fibers to a variety of weapon sights is disclosed in the present inventor&#39;s co-pending U.S. patent application No. 08/506,722, filed Jul. 26, 1965. However, in both of the above-disclosed sight arrangements, if a natural light source is not available, such as under nighttime conditions, the end of the fiber is not noticeably visible. 
     Attempts to provide a weapon sight suitable for use under both daylight and nighttime conditions include reticles illuminated by an artificial light source, such as a small incandescent bulb, and light-emitting diodes. These arrangements require a source of electrical power such as batteries, rendering the device cumbersome and susceptible to failure if the electrical power source is interrupted. Other attempts to provide a weapon sight for use under day or night conditions includes the use of small phosphorescent dots or other shapes painted directly onto a portion of the sight. This latter arrangement often compromises the visibility of the sight under bright light conditions. 
     The present invention is directed to overcoming the problems set forth above. It is desirable to have a sight for weapons that is readily visible in the brightness of day or the darkness of night. It is also desirable to have such a sight that is easy to see and hold in a user&#39;s line of vision while aligning the weapon with a target. Furthermore, it is desirable to have such a weapon sight that does not require a powered light source. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention, a weapon sight includes an elongated optical fiber formed of a light-gathering, fluorescent plastic material. The elongated optical fiber has a first end in which light is emitted to provide an aiming indicia, a second end spaced from the first end, and an outer surface extending between the first and second ends. The weapon sight further includes a holder, attachable to the weapon, that is adapted to support the elongated optical fiber. The weapon sight further includes a phosphorescent or light-emitting member disposed at a position adjacent the elongated optical fiber. 
     Other features of the weapon sight embodying the present invention include the light-emitting member being positioned elevationally below the elongated optical fiber when the holder is mounted on the weapon. Still other features include the light-emitting member being shaped to form an elongated strip having a surface aligned in parallel relationship with the elongated optical fiber. In other embodiments, the light-emitting member alternatively has a flat planar surface, or an angled or contoured surface adapted to focus light onto the outer cylindrical surface of the elongated optical fiber. The light-emitting member may include a film formed of phosphorescent paint, a plastic material containing luminescent pigment, or a light-emitting radioactive material. Yet other features of the weapons sight embodying the present invention include the light-emitting member additionally or solely being disposed adjacent a transverse end wall of the elongated fiber at the second end of the fiber. Also, the elongated strip embodiment of the light-emitting member may be in the form of a replaceable insert. Still other embodiments of the weapon sight include the light-emitting member having a body shaped to define a screw having an outer surface defining screw threads adapted to mate with screw threads formed in a portion of the holder, and an end face having a light-emitting material deposited thereon. In this arrangement, the screw-shaped body of the elongated light-emitting member is disposed in coaxial alignment with the elongated optical fiber. 
     In accordance with another aspect of the present invention, a weapons sight includes an elongated optical fiber formed of a light-gathering plastic material and a holder attachable to a weapon and adapted to support the elongated optical fiber. The weapons sight further includes an elongated light-reflecting member disposed at a position adjacent the elongated optical fiber. 
     Other features of the weapon sight embodying the present invention include the light-reflecting member comprising a film formed of light-reflective paint or a solid insert having a light-reflective surface. The light-reflective surface may either be a flat planar surface aligned in parallel relationship with the elongated optical fiber or a contoured surface adapted to focus reflected light onto an outer cylindrical surface of the elongated optical fiber. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete understanding of the structure and operation of the present invention may be had by reference to the following detailed description when taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is an elevational view of a rifle having a front sight embodying the present invention; 
     FIG. 2 is a three-dimensional view of a handgun having a front sight embodying the present invention; 
     FIG. 3 is a three-dimensional view of a sight pin and adapter embodying the present invention, arranged for mounting in a dovetail bracket attachable to a bow; 
     FIG. 4 is a three-dimensional view of a weapon sight embodying the present invention; 
     FIG. 5 is a longitudinal sectional view of a weapon sight embodying the present invention; 
     FIG. 6 is a longitudinal section view of another arrangement of the weapon sight embodying the present invention; 
     FIG. 7 is a longitudinal section view of still another arrangement of the weapon sight embodying the present invention; 
     FIG. 8 is a longitudinal section view of yet another arrangement of the weapon sight embodying the present invention; 
     FIG. 9 is a partially sectioned view of the weapon sight embodying the present invention, adapted for mounting in a bracket attachable to a bow; 
     FIG. 10 is a partially sectioned view of one end of a weapon sight embodying the present invention, adapted for mounting on a bow; 
     FIG. 11 is a three-dimensional view of another arrangement of the weapon sight embodying the present invention; 
     FIG. 12 is a planar sectional view of the weapon sight, embodying the present invention, shown in FIG. 11; 
     FIG. 13 is a three-dimensional view of a handgun having a U-shaped rear sight in combination with a front sight, both of which embody the present invention; 
     FIG. 14 is a rear view of the handgun sight arrangement shown in FIG. 13, with the gun properly aligned with the front sight laterally positioned between the rear sight dots; 
     FIG. 15 is a fragmentary three-dimensional view of another arrangement of a weapon sight embodying the present invention, showing a row of fibers aligned side-by-side in a planar array to provide an elongated sight line; and 
     FIG. 16 is a rear view of a gun having a rear sight as shown in FIG. 15, and a front sight, both of which embody the present invention, when the gun is properly aligned elevationally and laterally, with the front sight dot centered on the elongated sight line at the mid-point of the line. 
    
    
     DETAILED DESCRIPTION OF PRESENTLY PREFERRED EXEMPLARY EMBODIMENTS 
     A weapon sight  10  embodying the present invention is adaptable for use on a multitude of weapons such as a rifle  12  as shown in FIG. 1, a handgun  14  as shown in FIG. 2, or mountable in a bracket  16  attachable to a bow as shown in FIG.  3 . The term “weapon” as used herein and in the claims means weapons used in military, law enforcement, hunting, recreational or other applications, including toy weapons. Thus, the weapon sight  10 , provides an aiming indicia for any such weapon. In the preferred embodiments the sight  10  is mountable in a holder  18  as shown in FIGS. 4-8, or alternatively in a tubular holder  42  as shown in FIGS.  3  and  9 - 12 . 
     In all of the below-described embodiments, the sight  10  includes an elongated optical fiber  20  formed of a light-gathering plastic material. Such fibers are usually formed of fluorescent dye polymers having a diameter of approximately 0.030 inches (0.08 mm), and typically range from about 0.020 inches (0.05 mm) to about 0.080 inches (0.20 mm), and are capable of gathering light through the external cylindrical surface along the length of the fiber to conduct and focus gathered light at the transverse end surfaces. In the present embodiments, the elongated optical fiber  20  has a first end  22  at which light is emitted to provide a weapon user&#39;s aim point indicia, and a second end  24  spaced from the first end  22  which, in certain embodiments, also acts as a light-gathering surface. The light-gathering outer surface of the elongated optical fiber  20  extends between the first and second ends  22 ,  24  of the fiber  20 . The ends  22 , 24  of the fiber  20  are typically flared to form a lens providing a larger dot source of emitted light or, alternatively, an enlarged light-gathering surface. 
     The holder  18  is adapted to support the elongated optical fiber  20 , and may be either permanently attached to a weapon, or detachably connected to the weapon by screws extending through holes  26  at the ends of the holder  18  and into engagement with threaded holes provided in the barrel of the weapon. Other detachable mounting arrangements include attachment with a removable adhesive material such as double-sided tape or magnets. Also, the holder  18  may comprise an elongated protective tube by itself, or in conjunction with a bracket for other fixture attached to the weapon, e.g., the bracket  16  that is attachable to a bow as illustrated in FIG.  3 . 
     Importantly, each arrangement of the sight  10  embodying the present invention includes a phosphorescent, other light-emitting, or a light-reflecting member which provides a source of illumination to the elongated optical fiber  20 . The term “phosphorescent”, as used herein and in the claims, means a material characterized by the ability to provide luminescence that persists after the removal of an exciting source which may include natural or artificial light. The term “light-emitting”, as used herein and in the claims, means any light source that emits electromagnetic radiation in the visible light spectrum by luminescence, including phosphorescence and emitted light resulting from the radioactive decay of materials which produce radioluminescence. In the first embodiment shown in FIG. 4, an elongated, phosphorescent or light-emitting member  28  is disposed on the holder  18  at a position adjacent, and in substantially parallel relationship with, the elongated optical fiber  20 . When the holder  18  is mounted on a weapon, the elongated light-emitting member  28  is positioned elevationally below the optical fiber  20 . 
     The phosphorescent member  28  may advantageously be formed of a material containing phosphorescent, or long-afterglow, pigments. Long-afterglow pigments, such as LUMILUX® -pigments, produced by Riedel-deHaën of Seeize, Germany, possess the property of emitting light while they are being excited and also for a long time thereafter. This phenomenon, as defined above, is known as phosphorescence, or afterglow, and can be perceived by a person whose eyes have become adapted to the darkness, even several hours after the source of excitation has been removed. Excitation and emission can be repeated indefinitely. Fatigue of the basic luminescent mechanism does not occur. Both daylight and white artificial light are suitable sources of excitation. These materials are typically used for the production of long-afterglow safety products such as warning, mandatory and escape route signs. Long-afterglow pigments are available as paints, epoxy fillers, plastic films, plastic plates, enamels, and molded plastic articles. In the present invention, the long-afterglow pigments may be incorporated in a paint or enamel applied directly to the surface of the holder  18  adjacent the elongated optical fiber  20  to form a film of the material  30 , as shown in FIG.  4 . 
     Alternatively, the long-afterglow pigments may be incorporated in a phosphorescent molded plastic insert  32  disposed on the holder  18  at a position adjacent, and elevationally below the elongated optical fiber  20 , as shown in FIGS. 5 and 6. When provided as a film  30  or molded insert  32 , the member  28  may be selectively replaceable. For example, the paint film  30  may be provided on an adhesive tape that is applied to the surface of a holder  18  or directly onto an underlying surface of the weapon itself. In a similar manner, the molded insert  32  may be shaped to snap into a recess provided in the upper surface of the holder  18 . 
     Preferably, the phosphorescent or light-emitting member  28 , in whichever of the above- or below-described forms, is spectrally matched with the light absorption characteristics of the optical fiber  20 , so that the wavelength of the emitted light is efficiently absorbed by the optical fiber  20 . That is, the light-emitting member  28  generally has optimal light emission intensity within a defined wavelength range. Therefore, it is desirable that the optical fiber  20  have optimal light gathering characteristics that fall within the optimal light emission wavelength range of the light-emitting member  28 . By matching the light-emitting and light-absorbing characteristics of the two components,  28 , 20 , the intensity of light emitted at the end, or ends, of the fiber  20  will be enhanced. Furthermore, the elongated light-emitting member  28  may, with appropriated shielding, comprise a radioactive light-emitting source, such as tritium and similar radioluminescent materials. 
     In other arrangements, the elongated, phosphorescent or light-emitting member  28  may be used in cooperation with a phosphorescent surface provided at the second end  24  of the elongated optical fiber  20 , as shown in FIGS. 6 and 7. In the FIG. 6 arrangement, the elongated phosphorescent member  28  extends beyond the second end  24  of the optical fiber  20  and has an upwardly extending portion  34  adjacent the transverse end wall defining the second end  24  of the fiber  20 . Thus, in this arrangement, the phosphorescent member  28  not only provides a source of light along at least a portion of the length of the optical fiber  20 , but also provides a source of light directed into the end wall at the second end  24  of the fiber  20 . 
     In another arrangement, shown in FIG. 7, the sight  10  includes a phosphorescent or light-emitting member  38  that is disposed in the holder  18  at a position adjacent the second end  24  of the elongated optical fiber  20 . The light-emitting member  38  is positioned to direct emitted light onto the transverse end wall at the second end  24  of the fiber  20 . As shown in the drawing, the phosphorescent or light-emitting member  38  may comprise a body  100 , formed of a plastic material, that is shaped to form a screw  102  having an outer surface defining screw threads adapted to mate with screw threads formed in the holder  18 . In this arrangement, the end face of the light-emitting member  38  is coated with a phosphorescent or other light-emitting material, such as the above-described phosphorescent paint, plastic material containing luminescent pigment, or radioactive material such as tritium. In this arrangement, the light-emitting member  38  is disposed at the second end of the fiber  20  and may be used in conjunction with the previously described elongated-light-emitting member  28 , as shown in FIG. 7, or alternatively by itself, as a sole source of light. 
     In yet another arrangement, shown in FIG. 8, a light-emitting member  36  has a body shaped to define a hollow screw with an internal bore adapted to mate with a portion of the outer cylindrical surface of the elongated optical fiber  20  and an outer surface that defines screw threads adapted to mate with screw threads formed in a portion of the holder  18 . In this arrangement, the end face of the light-emitting member  36  is coated with a phosphorescent or light-emitting material such as the above-described phosphorescent paint, plastic material containing luminescent pigment, or radioactive material such as tritium, which emits light into a clear disk  40 . The disk  40  directs light emitted from the member  36  onto the light-gathering outer surface of the optical fiber  20  at the first end  22  of the fiber  20 . In this arrangement, both the light-emitting member  36  and the disk  40  are coaxially aligned with the elongated optical fiber  20 . If desired, the coaxially aligned light-emitting member  36  may have a cross-sectional shape other than circular, for example, triangular, rectangular, octagonal or other shape. 
     In still other arrangements of the sight  10  embodying the present invention, the phosphorescent or light-emitting member  36  may comprise a small cylindrical capsule  42  of phosphorescent material, or radioactive material such as tritium, having a diameter substantially equal to that of the optical fiber  20 . In this arrangement, the capsule  42  is protectively shielded by a tubular holder  44 , as shown in FIG.  9  and is particularly suited for mounting in the bracket  16  which is attachable to a bow. Alternatively, the member  36  may include a coating of phosphorescent or radioactive light-emitting material disposed on an internal recessed end face  46  of a cap  48 , adapted to enclose the second end  24  of the optical fiber  20 , as shown in FIG.  10 . 
     In yet another arrangement, the elongated optical fiber  20  may have a “U” shape, as shown in FIGS. 11 and 12. In this arrangement, a phosphorescent or other light-emitting source may be disposed at the second end  24  of the fiber  20  which forms the base of one leg of the “U”, with the light-emitting first end  22  of the fiber  20  forming the base of the other leg of the “U”. The “U” arrangement provides a significantly increased exposed length of outer surface area of the fiber  20  to enhance the light-gathering characteristics of the sight  10 , and is particularly suitable for use as a bow sight. 
     Alternatively, the light-emitting member  28  of the weapon sight  10  may comprise an elongated member disposed on the holder  18  at a position adjacent the elongated optical fiber  20  that emits reflected light. For example, the film of paint  30  or the molded insert  32 , as shown in FIGS. 4-6, may simply have a light-reflective surface rather than a luminescent, phosphorescent, or radioluminescent surface. Although not as effective in conditions of absolute darkness, a light-reflective surface is effective in directing small amounts of light, such as bright moonlight or starlight on a clear night, to the light-gathering exterior wall of the elongated optical fiber  20 . A suitable light-reflective surface may be advantageously provided by a strip of white material, such as paint, enamel or tape, or by a highly reflective polished or mirrored surface on the holder or the weapon. 
     In the above-described arrangements, i.e. either as a light-emitting surface or as a light-reflecting surface, the elongated member disposed elevationally below the optical fiber  20  may have a flat planar surface, or an angled or contoured surface shaped to direct or focus light onto the cylindrical light-gathering surface of the elongated optical fiber  20 . 
     If desired, the holders  18 , 44  in either the gun or bow application arrangements, may be formed of a clear plastic material to increase the surface area of the optical fiber  20  exposed to available light. Alternatively, the holder  18 , particularly in the gun application arrangements shown in FIGS. 1,  2 , and  4 - 8 , may have a slotted opening at the top which may be spread to permit insertion of the fiber  20  into the fiber-receiving bore. In yet another arrangement, the holder  44 , adapted for use on a bow as shown in FIGS. 3, and  9 - 12 , may have a phosphorescent or light -reflective surface provided on either the internal bore or outer surface of the tubular holder  44 , in the form of a strip positioned elevationally below the optical fiber  20  when the holder  44  is inserted in the bracket  16  and mounted on a bow. It should also be noted that the elongated light-emitting member  28 , shown in FIGS. 4-7, may be formed of an encapsulated radioactive material such as tritium. 
     The weapon sight  10  embodying the present invention, is also applicable to a rear sight of a gun, either singly or in combination with a front sight, or to multiple sights on a bow. For example as shown in FIG. 13, a handgun  14  may have an optical fiber  50  arranged in a U-shape providing two spaced-apart horizontally aligned dots  52 ,  54  as a rear sight, and an elongated optical fiber  20  providing a single dot  56  front sight. As described above, both sights  50 , 20  have a light-emitting member  28  disposed at a position adjacent the respective fibers  50 , 20  to provide illumination of the respective end faces  52 , 54 , 56  under dark or low-light conditions. As shown in FIG. 14, when properly aligned, the dot  56  provided by the front sight  20  is laterally positioned midway between the two dots  52 , 54  at the end of the U in the rear sight  50 , with the bottom of the front dot  56  elevationally aligned with a line  58  extending across the top of the rear sight dots  52 , 54 . Desirably, for ease of identification and alignment, the front sight  56  and the rear sights  52 , 56  may be formed with optical fibers having different wavelength emission properties, e.g. red and green. Also, if desired, the U-shaped rear fiber  50  may be curved or mounted at an angle such that the bottom portion of the U does not block observation of the front sight  28 , thereby permitting horizontal alignment of the three dots  52 , 54 , 56  as an aiming indicia. 
     It should also be noted that the elongated optical fiber may be arranged in a modified U-shape in which one leg of the U is shortened to form a J-shape wherein either one or both ends of the fiber are positioned to provide an illuminated dot, generally as a front sight as described in the aforementioned copending U.S. application No. 08/506,722. The above-described arrangements of the light-emitting member  28  may also be used in combination with such J-shaped light-gathering optical fiber sight structures. 
     Also, a row of fibers  20 , aligned side-by-side in a planar array  60 , as shown in FIG. 15, forms a row of dots which provide an elongated sight line. The row of fibers  20  may be arranged in either a horizontal or vertical orientation, and may be used in either a front sight, a rear sight, or both. When provided with a light-emitting or light reflecting member  28 ,  36  positioned below or at one end of the planar array  60 , a bright horizontal line is produced under low light or dark conditions. The planar array  60  rear sight may be used in conjunction with the elongated fiber  20  front sight described above. In this arrangement, when the gun is properly aligned elevationally and laterally, the front sight dot  56  is centered on the horizontal sight line provided by the planar array  60  at the mid-point of the array  60 , as illustrated in FIG.  16 . 
     Moreover, the above-described light-emitting materials, i.e. phosphorescent paint, plastic containing luminescent pigments, or radioluminescent light source, may be applied directly to a portion of the optical fiber  20 . For example, the phosphorescent or light-emitting material may be applied as a coating on one-half of the circumference of the fiber along its length, or completely around the fiber over only a portion of its length. 
     Thus, it can be seen that the weapon sight  10  embodying the present invention is readily usable as an aiming indicia for a weapon in either bright daylight, nighttime, or in any lighting condition between the two. In the daytime, the light-gathering optical fiber  20  provides a bright dot at the first end  22  of the fiber  20  that is instantly observable and provides a bright dot light source for use as an aiming indicia against virtually any background. Under low light and dark conditions, the light-emitting or light-reflective member, disposed elevationally below or in coaxial alignment with the optical fiber  20 , serves to illuminate the optical fiber  20  to produce a bright dot at the first end  22  of the fiber  20  that is readily identifiable under the low light or dark ambient conditions. 
     Although the present invention is directed in terms of preferred exemplary embodiment, with specific illustrative key constructions and arrangements, those skilled in the art will recognize that changes in those arrangements and constructions, and in the specifically identified materials, may be made without departing from the spirit of the invention. For example, the construction of the holder  18  may be modified to accommodate specific weapon or use requirements. Such changes are intended to fall within the scope of the following claims. Other aspects, features, and advantages of the present invention may be obtained from a study of this disclosure and the drawings, along with the appended claims.