Abstract:
An optical bow sight which can be accessorized with an adjustable range sighting pin or torque and cant compensation or both of these features, but is fully functional without either accessory. The optical sight has a shrouded array of fiber optics sight pins which are removable from the sight housing with their support as a single unit. The sight pins are clad in a metallic glass because of the corrosion resistance of such materials. Light collected over a wide field falls on segments of the sight pin fibers coiled in the housing of the optical unit or falls on a trap which redirects the light onto the fiber segments. A lens may optionally be employed to promote the collection of ambient light, and a shutter or variable size aperture may be provided to control the light reaching the sight pin fibers. An elastomeric damper can be advantageously mounted on the sight to minimize accuracy effecting shock and/or vibration, and a level bubble may be provided to aid in avoiding cant of the bow to which the sight is mounted.

Description:
CROSS-REFERENCE TO A RELATED APPLICATION 
     Applicants are entitled to and hereby claim, the priority of provisional application No. 60/879,944 filed 10 Jan. 2007. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to novel, improved, archery bow sights. 
     BACKGROUND OF THE INVENTION 
     A common type of archery bow sight employs a set of vertically-spaced apart sight pins, each corresponding to a different range (distance to a target). These pins are installed in a frame which is mounted to the riser of the bow. 
     In low-light conditions, those ends of the pins used for sighting can be difficult to see clearly, if at all. Accordingly, it has been proposed that the sighting ends of the pins be illuminated. 
     One approach that has been suggested involves the use of fiber optics to illuminate the sighting ends of the pins. Sights of that character are disclosed in U.S. Pat. Nos.: 5,435,068 issued 25 Jul. 1995 to Thames, et al., and 7,082,690 issued 1 Aug. 2006 to Knoshnood. 
     SUMMARY OF THE INVENTION 
     There have now been invented and disclosed herein new and novel bow sights which likewise employ fiber optics, but have a number of significant features and advantages which are not possessed by previously proposed, fiber optics bow sights. 
     One such feature is a light collecting system which gathers light over a wide hemispherical field and thereby significantly increases the amount of light that can be transmitted to the sighting ends of the pins, which are the terminal segments of optical fibers. This makes those ends readily visible under even extremely poor lighting conditions. That the sight provides bright, easily seen aiming points when the ambient light is poor is significant because a number of jurisdictions do not allow artificial light to be used in hunting game. 
     A companion feature of the sights disclosed herein is that the optical fibers are side-loaded as well as end-loaded. This significantly increases the efficiency with which light can be loaded into the fibers. Also, maximizing fiber optic loading reduces the needed lengths of the fibers, which is advantageous from the viewpoints of cost, manufacturability, and serviceability. 
     A second, related feature is a novel light trap for the collected light. The light trap redirects the collected light onto the optical fibers and also makes a significant contribution to the efficiency of the sight. 
     Another important feature of the present invention is the encapsulation of the exposed optical fiber segments constituting the sighting pins in a metallic glass such as one of those available from Liquidmetal Technologies. These materials are extremely resistant to corrosion, which is a common problem, particularly in the sights of hunting bows. Metallic glasses may be lighter than competing materials such as steel, have considerable flexibility, and are readily molded. 
     Yet another feature of the present invention is a novel modular construction which allows a fully functional basic sight to be upgraded to provide additional features. One module adds an adjustable sighting pin for more distant ranges to the sight. Another add-on provides adjustable torque and cant compensation for the bow on which the sight is mounted. 
     Also significant is the attachment of elastomeric dampers akin to those disclosed in U.S. Pat. No. 5,362,046 issued Nov. 8, 1994, to Sims to the sight at strategic locations. These dampers significantly reduce shock and vibration loads imposed on the sight when the bow is fired, contributing to accuracy and increased service life of the sight, reducing the sound made when the bow is fired, and reducing the possibility of shock and vibration knocking the sight out of alignment. 
     It is another feature of the invention that the sighting pins and supporting frame are removable from the installable in the sight as a single unit. This is important from the viewpoints of manufacturability and serviceability. Also, this feature makes it convenient for the archer to use interchangeable sight pin units to optimize the bow for different poundage settings and arrow weights. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of the compound bow equipped with a bow sight which is constructed in accord with, and embodies, the principles of the present invention; 
         FIG. 2  is a fragmentary view of the bow and the sight; this view is to a larger scale than  FIG. 1  and is of the opposite side of the bow and sight; it is the basic, albeit fully functional, sight that is shown in this figure; 
         FIG. 3  is a perspective view of the bow sight; two bow sight add-ons (or accessories) are also shown; 
         FIG. 3A  is a perspective view of one of an array of sight pins which are components of the  FIG. 1  bow sight; 
         FIG. 3B  is a horizontal section through the  FIG. 3A  sight pin; 
         FIG. 3C  is a front-to-rear perspective view of an assembly of the array of sight pins and a sight pin support; this assembly can be removed from and installed in the sight as a unit; 
         FIG. 4  is a rear view of the bow sight; 
         FIG. 5  is a plan view of an add-on used to adjust the torque on, and the cant of, the bow; 
         FIG. 6  is a perspective view of an add-on used to provide an additional sighting pin that can be adjusted for (typically) longer range shots; 
         FIG. 7  is a front view of the bow sight; 
         FIG. 8  is a top view of the bow sight; 
         FIG. 9  is a perspective view of an optics unit employed in the  FIG. 1  bow sight; this figure shows a single one of the light transmitting, pin sight fibers; these optical fibers are housed in and coiled against the side wall of the optics unit casing; 
         FIG. 10  is a side view of the bow sight; 
         FIG. 11  is a perspective view of a component of the  FIG. 5  add-on configured to provide for adjustment of the cant of the bow; 
         FIG. 12  is a fragmentary view of the bow sight included to show a level with a bubble that is centered for cant-free, optimum bow performance; 
         FIG. 13  is a vertical section through a light trap; this trap is a component of the optics unit of the  FIG. 1  bow sight; 
         FIG. 14  is a perspective view showing: (a) a fragment of the bow sight including the optics unit, and (b) an elastomeric diaphragm mechanism that can be employed to control the light reaching the light trap of the optics unit; 
         FIG. 15  is a section through the optics unit and the elastomeric diaphragm mechanism; 
         FIG. 16  is a perspective view of the optics unit and an adjustable shutter mechanism that can be employed to control light reaching the optics unit light trap; and 
         FIG. 17  is a view like  FIG. 16  but with the shutter of the light controlling mechanism adjusted to further restrict the light reaching the light trap. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     Referring now to the illustrations,  FIGS. 1 and 2  depict a compound bow  20  equipped with a fall-away arrow rest  22 , an optical sight  24 , and a modular stabilizer  26 . Bow  20  is of conventional construction. It has a riser  28 , upper and lower limbs  30  and  32 , cams  34  and  36  at the far ends of limbs  30  and  32 , bus cables (collectively identified by reference character  38 ) a bow string  40 , and a cable slide  42  mounted on an elongated guide  44 . 
     Bow sight  24  includes a basic unit  46  ( FIG. 2 ), an optional add-on or accessory  48  ( FIG. 3 ) which provides an additional sighting capability, and a second, also optional, add-on or accessory  50 . This accessory is employed to adjust torque and cant. 
     The basic unit  46  is assembled directly to the riser  28  of bow  20  ( FIG. 2 ). If the torque and cant compensation accessory  50  is added, the add-on is assembled to the basic unit; and it is a mounting component of the accessory which is mounted to bow riser  28 . 
     Referring now most particularly to  FIGS. 2 ,  3 ,  4 ,  7 ,  8 , and  10 , the basic bow sight  46  includes a mounting bracket  54  and a complementary component  56  which functions as a housing and as a support for optical components of the sight. The two components  54  and  56  are connected by a slot-and-dovetail arrangement  58  and a threaded fastener  60 . The latter clamps the two legs  62  and  64  of bracket  54  together to securely assemble components  54  and  56 . 
     The two legs  62  and  64  of mounting bracket  54  are attached to the riser  28  of bow  20  as by the headed and threaded fasteners  66  and  68  shown in  FIG. 2  to mount sight  24  to the bow. 
     A plate  70  located therebetween integrates the legs  62  and  64  of mounting bracket  54  into a unitary structure. 
     The support/housing component  56  of bow sight  24  and the components housed in and supported from that component are best shown in  FIGS. 2 ,  3 ,  3 A- 3 C,  4 ,  7 , and  8 . 
     Referring now to these figures, it was pointed out above that optical bow sights embodying the principles of the present invention employ vertically-spaced apart sight pins, each of these pins corresponding to a different bow-to-target range. The sight pins of bow sight are identified by reference characters  74  . . .  82 . 
     The sight pins are composed of optical fibers encased in protective housings that are preferably made from a metallic glass. Housings fabricated from the preferred materials are highly resistant to corrosion in contrast to the rust-susceptible metallic pin components of conventional bow sights. Reference characters  82   f  and  82   h  in  FIGS. 3A and 3B  respectively identify the optical fiber and housing of representative sight pin  82 . 
     The sight pins  74  . . .  82  are mounted to a pin support  83 , forming a sight pin assembly  85  (see  FIG. 3C ). Assembly  85  is housed in bow sight housing/support component  56 , which also supports the casing  84  of an optics unit  86 . The assembly  85  can be removed from component  56  as a unit, which is advantageous from the viewpoints of manufacturability, serviceability, and interchangeability. 
     In the currently preferred sight pin assembly shown in  FIG. 3C , sight pins  74  . . .  82  are installed in a selected two of three vertical slots  88 ,  90 , and  92  in sight in support  83 , slot  88  being nearest the front of the support and slot  92  being nearest its rear. Alternate pins are installed in slots  88  and  90 , pins  74 ,  78 , and  82  thus being installed in front slot  88  and pins  76  and  78  being installed in center slot  90 . Rear slot  92  provides a protected path for the optical fibers. 
     The distal ends  94  . . .  102  of the sight pin optical are exposed (see  FIG. 7 ). It is these exposed, dot-like features of the sight pins with which a target is acquired. The sight pin housings are curved such that the optical fibers are supported from pin support (or frame  83 ) with sight features  94 - 102  facing the archer. 
     The array  104  of sight pins  74  . . .  82  is surrounded by a shroud  106 , also to protect the pins from damage. Shroud  106  is an integral component of support/housing component  56 . 
     As shown in  FIG. 2 , the optical fibers of sight pins  74  . . .  82  are trained through bow sight component  56  to the optics unit  86  of the bow sight. There, the fibers are coiled, one above the other, against the inner side  108  of optics unit casing  86 . The lowermost optical fiber  109  (of sight pin  82 ) is shown in  FIG. 9 . 
     The casing  84  of optical unit  86  has inner surfaces, described below, which are elements of a light trap  110  ( FIGS. 8 and 13 ). The casing supports a light collecting lens  112  directly above, and in axial alignment with, light trap  110  at the open end  114  of casing  84 . 
     Light trap  110  is a one-piece, typically injection molded component (see  FIG. 13 ). The light trap includes: the inner surface  115   i  of the bottom wall  115  of casing  84 ; the inner surface  116   i  of casing side wall  116 ; and a conical, cored-out, integral element  117  with: (a) a uniform wall thickness “I”, (b) a base  118 , (c) an apex  119 , and (d) a convex external surface  120 . The light trap may be made from any appropriate polymer as by injection molding, for example. The light trap surfaces are coated by vapor deposition or otherwise treated to make those surfaces highly reflective. 
     Lens  112  gathers light from a field which encompasses almost an entire hemisphere. Light reaching light trap  110  through lens  112  may fall on the external surface  120  of conical element  117 , the optical fibers in and coiled against the wall  116  of casing  84 , the inside surface  116   i  of wall  116 , or the inner surface  115   i  of casing bottom wall  115 . Light that does not directly strike the optical fibers is reflected and/or redirected onto the fibers. Therefore, essentially all of the incident light reaches and is loaded into the fibers; and the optical unit is highly efficient in collecting light from the ambient surroundings and in insuring that the collected light reaches the optical fibers for transmission through the fibers to the sighting dots  94 - 102  at the ends of the fibers. 
     Lens  112  is not a mandatory component of optical bow sights embodying the principles of the present invention. Even without a lens, light will fall on and into light trap  110  and be loaded into the optical fibers housed in casing  84  essentially in the manner discussed above. 
     Turning now primarily to  FIGS. 3 ,  5 ,  8 , and  10  the torque and cant adjustment accessory or add-on  50  includes two brackets,  121  and  122 , connected by a vertically-extending hinge pin  124  and a mounting bracket  126  which replaces the mounting bracket  54  of the basic bow sight  46 . Mounting bracket  126  is assembled to bracket  122  with threaded fasteners  128  and  130  ( FIG. 5 ). The optical components of sight  46  are attached to mounting bracket  126  of accessory  50  in the same above-discussed manner and with the same type of slot-and-dovetail coupling and threaded fastener that those components are attached to mounting bracket  54  of basic bow sight  46 . 
     A variety of factors, such as a particular archer&#39;s grip, the balance of the bow, the angle of a shot, whether the archer is shooting from a tree stand or other elevated position, shooting uphill, etc. causes the archer to impose torque—that is a force pivoting the bow to the left or right about a vertical axis—on the bow. An important feature of accessory  50  is that it can be employed to provide compensation for the torque. Specifically, by tightening setscrew  132 , bracket  121  and the optical components carried by that bracket, especially the sighting pins, are shifted to the right, i.e., in the direction indicated by arrow  132  in  FIG. 5 . Conversely, by tightening complementary setscrew  136 , bracket  121  is shifted in the opposite direction to move the supported optical components to the left. 
     The fastener  128  securing the mount  121  of accessory  50  to optical unit-supporting bracket  126  extends through a laterally oriented adjustment slot  138  in the support (see  FIG. 11 ) and is threaded into mount  121 . 
     The cant of the optical sight is adjusted by loosening fasteners  128  and  130 , rotating optical unit support  126  about the lower fastener until the bubble  140  of a level  142  mounted on the bottom of sight pin shroud  106  (see  FIG. 12 ) is centered, and then retightening fasteners  128  and  130 . This cant compensation adjustment can contribute significantly to accuracy. 
     Turning now most particularly to  FIGS. 3 ,  5 , and  6 , it was pointed out above that the optional add-on or accessory  48  is employed to provide a sight pin for a range greater than those ranges for which sight pins  74  . . .  82  are intended. Accessory  48  is bolted or otherwise mounted to the basic bow sight unit  46  in the location shown in  FIGS. 3 and 4 . 
     Accessory  48  includes a sight pin  144  mounted to a support  146 , a carriage  148 , and an elongated, threaded member  150  supported from and rotatable in, the carriage. The threaded member is rotated by a knob  152  fixed to member  150  by setscrew  154 . 
     Carriage  148  has end plates  156  and  158 . Posts  160  and  162  extend between and are mounted at their opposite ends to end plates  156  and  158 . Threaded member  150  is located equidistantly between posts  160  and  162  as shown in  FIG. 6 . 
     Sight pin support  146  can be moved vertically up and down on posts  160  and  162  as indicated by double-headed arrow  164  in  FIG. 6 . Specifically, elongated member  150  is threaded through an internally-threaded extension  166  of sighting pin support  146 . Consequently, as the threaded member  150  is rotated, the support  146  and sight pin  144  are moved vertically up and vertically down to locate the aiming point  168  at the end of the sighting pin at the height appropriate for a selected bow-to-target range. The support is locked in place by rotating knob  170 . 
     The aiming feature  168  of sight pin  144  can be moved in and out of sight pin mount  146  to align aiming feature  168  with respect to the aiming features  94  . . .  102  of sight pins  74  . . .  82 . This is accomplished by loosening a screw  171  threaded into pin mount  146 , shifting the sight pin into or out of support  146  as indicated by double-headed arrow  172 , and then retightening the screw. 
     As is best shown in  FIGS. 3 and 4 , there is a dimple  174  at the bottom of sight pin shroud  106 . This increases the distance over which the sighting end  168  of sight pin  144  can be displaced with a concomitant increase in the ranges for which sight pin  144  can be used. 
     Another important feature of the present invention, employed whether or not it is the basic sight  46  that is involved, or that sight with one or both of the accessories  48  and  50  discussed above, is an elastomeric shock and vibration damper  176 . In the case of the basic unit, the damper is mounted on that vertical wall  178  of bow sight component  56  opposite mounting bracket  54  (see  FIG. 2 ). If accessory  48  is also present, damper  176  is instead mounted on that side of the accessory opposite the basic bow sight  46  (see  FIGS. 3 and 4 ). Damper  176  makes a significant contribution to smooth and quiet operation of bow  20 ; and it reduces the possibility that shock and/or vibration might damage bow sight  24 . 
     It is advantageous to be able to control the light which reaches light trap  110 . This can be done with, for example, an apertured elastomeric boot  182  as shown in  FIGS. 14 and 15  or an adjustable shutter mechanism  184  as shown in  FIGS. 16 and 17 . 
     Boot  182  has a side wall element  186  and an integral diaphragm  188  with a central aperture  190 . The boot is slid down over optics unit casing side wall  116  and retained in place by friction. The size of aperture  190  controls the light reaching light trap  110 . By exerting a downward, arrow  192  force on the boot, the diaphragm  188  can be stretched, increasing the size of aperture  190  and, consequentially, that proportion of incident light reaching trap  110 . 
     The shutter mechanism  184  shown in  FIGS. 15 and 16  has a cylindrical casing  196 , a stationary plate  198 , and a complementary shutter  200 . 
     Plate  198  and shutter  200  have arrays  202  and  204  of complementary trapezoidal apertures  206  and  208 . Plate is fixedly mounted in the upper end of casing  196 , and shutter  200  is mounted above plate  198  for rotation about a vertical axis  210 . 
     Rotating shutter  200  about axis  210  changes the fraction of incident light that can reach light trap  110  through apertures  206  and  208 . With shutter  200  rotated relative to plate  198  as shown in  FIG. 16 , the apertures  206  in plate  198  and the apertures  208  in shutter  200  are nearly aligned; and most of the incident light passes through aperture  208  and then aperture  206  to light trap  110 . When shutter  200  is rotated about axis  210  to the orientation shown in  FIG. 17 , imperforate areas  209  of the shutter span the major parts of the apertures  206  in plate  198 . This reduces the size of the aperture  206 ,  208  light passages, and, consequentially, substantially reduces that fraction of the incident light which can reach trap  110 . 
     Light controlling shutter mechanism  184  is assembled in any convenient manner over the open upper end  114  of optics unit casing  84 . 
     The light controlling mechanism shown in  FIGS. 14-17  can be employed irrespective of whether or not the optics unit of the associated bow sight has a lens. 
     The invention may be embodied in many forms without departing from the spirit or essential characteristics of the invention. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description; and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.