Patent Application
20070227018
Sights for bows have evolved dramatically in the last few decades. An early sight provided a track mounted to the bow and allowed for both windage and elevation adjustment of pins movably mounted to the track. Usually a plurality of pins were used and set for different predetermined ranges for the individual bow and archer. These sights provided an advance in the art for archers over earlier sighting methods. One earlier method of aiming included the use of a consistent nock end anchor point and then using the arrow tip as the front sight which was an effective method for skilled archers but not necessarily for occasional archers. Bows have likewise advanced dramatically in the last few decades from the traditional long bow or recurve bow to the so called compound bow. Crossbows have also made similar advances. Attachment of sight devices to a traditional bow such as a long bow or recurve bow posed problems with potential damage to the structural integrity of the bow sometimes causing the bow to fail particularly in laminated bows commonly referred to as fiberglass bows. Bows now have metallic risers that permit the attachment of numerous devices to the bow without risk of damage to the bow or its structural integrity. Such devices include sophisticated arrow rests, lights, sights with lenses, reels, stabilizers and pin sights. A second or rear sight can also be provided and may be mounted to the bow string to help improve accuracy. Modern bows with sights are extremely accurate and sophisticated. The modern bow is complex and can be considered a complex machine.
Bows that are used for hunting are used in highly variable conditions, particularly highly variable conditions of lighting both as to light intensity (e.g., lumens) and “color” (usually expressed in ° K.). The original multi-pin sight, while effective, had its drawbacks. A major drawback of such sights was the visibility of the pins in low light and when viewed on certain backgrounds or targets. Much hunting is done in the morning and in evening when light is low in intensity and/or color. Also, on overcast days, light can be sufficiently low to make the pins difficult to see and to see against a dark background as is not uncommon during hunting and also target shooting.
An early attempt to solve the sight pin visibility problem was to paint the tip of the pin with a light colored or luminescent paint usually using a different color for each pin. The plurality of colors on the pins was used to help quickly identify which range the pin was meant for. The next advance in such sights was to provide a low light-output battery-powered light which would be turned on selectively to illuminate the pins. However, this required batteries which could “burn out” or the light bulb could “burn out”. While effective, there were still disadvantages.
The next advance in sights was the use of fiber optics. Typically, such fiber optics were a single fiber polymeric fiber that absorbed light through the side which light would then project out of the ends of the fiber optic element or fiber. No batteries were required and such fiber optic sights have been commonly used for bow sights and other shooting device sights such as, pistol, rifle and shotgun sights. An easy to view dot of light was provided and no batteries were required. Additionally, such fiber optics could be made in a variety of colors which was beneficial for a multi-pin sight, such as that used on a bow, to help quickly provide differentiation as to which range pin was being viewed. However, even these sights had drawbacks. Sometimes, to gather enough light, the fiber optic was made longer than was convenient for use on a small sight. Additionally, the diameter (the fiber optic fiber was typically round in transverse cross-section) of the sighting end of the fiber optic tended to be large in order for the fiber optic to gather enough light to be readily viewable. The size of the sighting end sometimes interfered with viewing of the target.
One major drawback of fiber optic sights is that when the sight is tuned for low light, to provide enough light absorption and projection in a low light condition, the light projection was often too intense during high light conditions. To tune the sight for high light conditions would then mean not enough light was absorbed and projected for low light conditions. Thus, current sight technology presents mutually exclusive design and use criteria.
There is thus a need for an improved fiber optic sight.
The present invention involves the provision of a fiber optic sight that has a fiber with an outer surface extending between opposite end portions of the fiber. The fiber is adapted to gather light through the outer surface and provide visible light at at least one of the ends of the fiber. A light-responsive element is associated with the fiber. The light-responsive element is operable to regulate the amount of incident light absorbed by the fiber and respond to the ambient light impinging on the fiber. The light-responsive element may be an externally positioned shield, a coating on the fiber, or may be infused into the fiber itself. The light-responsive element is light sensitive and may reversibly change, e.g., in “color”, upon exposure to a specific wave length band of light such as ultraviolet light. Its ability to transmit light at a sighting end is reduced relative to a change in the incident light. The fiber can be mounted to a mount structure and be selectively movable relative to the mount structure. The mount structure in turn can be secured to an object such as a bow typically on the riser portion of the bow. Windage and elevation adjustments may be provided in the mount structure.
Like numbers throughout the various Figures designate like or similar parts.
The referenced numeral 1 designates generally a sighting device for use on a bow designated generally 2. Although the sight device is shown as a bow sight, it is to be understood that the sight device can also be utilized with such long-range weapons as rifles, pistols and shotguns as well as other devices that are aimed visually.
The bow 2 can be of any suitable type known in the art and, as shown, includes a riser 4, a top limb 5, a bottom limb 6, a string 7, an arrow rest 8 and a hand grip 10. In the case of a compound bow, a cam 11 may be mounted at either or both of the ends of the limbs 5 and 6. Other known devices may be mounted to the bow including a stabilizer, a reel and a quiver 9. Typically bow risers 4 are made of a metal alloy and the limbs can be made of a flexible fiberglass or other fibrous material such as graphite fibers. The riser 4 typically is provided with means for mounting various devices to the bow and typically include threaded holes for receipt of threaded fasteners such as Allen head cap screws or Torx® screws.
The sight 1 includes a mount structure 14 adapted for mounting the sight to a device to be aimed, for example, the bow 2. The mount 14 includes an arm 15 that is sized and shaped for securement to the riser 4 as, for example, with threaded fasteners 17. The sight 1 includes a frame structure 19 secured to the arm 15 preferably in a manner that allows the frame 19 to be movable relative to the arm 15 in at least one direction and preferably two orthogonal directions. Scales 20 may be provided for easy adjustment reference. As used herein, the terms vertical and horizontal are those directions as when the bow 2 or other object to be aimed is held in its normally upright orientation for aiming and use. In the illustrated structure, a first dovetail slide assembly 21 is movably mounted to a distal end 22 of the arm 15 and is movable horizontally relative to the arm allowing horizontal movement of the frame 19 with the sight pins 24 mounted to the frame 19. A second dovetail slide assembly 26 is mounted to the frame 19, and preferably to the first dovetail slide assembly 21, to permit selective vertical movement of the frame 19 relative to the arm 15. Horizontal movement of the frame 19 permits adjustment of the pins 24 for, what is commonly referred to as, windage and the second dovetail slide assembly 26 allows movement of the frame 19 for adjustment of the pins 24 for elevation (range). The frame 19 can be provided with one or more, and preferably two, tracks (not shown) in which the pins 24 are movably mounted to provide selective vertical spacing therebetween in order to provide aiming points for different ranges downrange to a target. The pins 24 can be mounted to the frame 19 by threaded fasteners 28 which permit the selective adjustment of the pins in spacing relative to one another. Thus, elevation can be adjusted by either moving the pins 24 and/or moving on the second dovetail slide assembly 26, and thereby the frame 19, in a vertical manner. The frame 19 can also be provided with a pin guard 30 to provide protection for the pins 24 from being damaged if the bow or other device to be sighted is dropped or accidentally strikes an object, e.g., a tree, vehicle or the like. A level indicator 32, such as a bubble level, can be provided on the frame 19 to indicate how close to vertical (and horizontal) the device to be aimed is oriented. An example of such a sight is the Skylight™ sight available from Montana Black Gold located in Bozeman, Mont.
The pins 24 have positioned adjacent a distal end 34 thereof, an illuminated end portion 33 of a light gathering fiber-optic fiber 35 so that the illuminated end 33 is visible by the person using the sight. The light gathering fiber 35 is mounted to the pin 24 in any suitable manner such as with clamp fingers 36 (
An intermediate portion 45 of a fiber 35 extends from the magazine 41 to the pins 24. It is preferred to protect the intermediate portion 45 from damage while still providing absorption of light along the intermediate portion. This can be done by providing a guard housing 47 having an interior chamber 48 thereby enclosing substantially the entirety of the intermediate portion 45 therein. It is preferred that the housing 47 have light-transmissive walls to allow for light to be incident upon the intermediate portions 45 and be absorbed thereby. A preferred material for the housing 47 and magazine 41 is polypropylene plastic which provides both durability, light transmission and protection for the fibers 35. A preferred light-sensitive material, such as photochromic material, for incorporation into the housing 47 and magazine 41 is polypropylene. As shown, the housing 47 is removably secured to the guard 30 such as by screw fasteners that extend through mounting brackets 51. It is preferred that the housing 47 and the intermediate fiber portions 45 contained therein are positioned on the front side of the sight 1 while the magazine 41 is preferably mounted on the top of the guard 30 providing greater access to light during normal shooting orientations of the bow or the like.
The bow sight 1 with accompanying fibers 35 is constructed to regulate the output of light from the sighting end 33 of the fibers 35 and, in one embodiment, in an automatic manner. Light output may be regulated by controlling the incident light absorption and/or the light transmission by and through a fiber-optic fiber 35. A light sensitive element is provided that is responsive to a change in a property or characteristic of the incident light and will regulate the amount of light transmitted from an end 33. The property of light utilized may include incident light intensity and/or color. This can be done by providing a fiber that reversibly changes transmissivity upon a change in the property level of incident light. In one embodiment, this can be done by providing an element associated with a fiber 35 that reversibly changes in response to a change in the intensity of light impinging on the fiber-optic fiber 35. For example, light in the UV (ultraviolet) range can activate photo-sensitive compounds that will reversibly change as the intensity of ultraviolet light changes. One method of and means of accomplishing this is through the use of photochromic materials. Photochromic materials are well known in the art. In one embodiment, the photochromic materials may be incorporated into the materials of the magazine 40 and housing 47. Thus, as light intensity increases, the photochromic element darkens reducing the amount of available light to be absorbed and/or transmitted by one or more of the fibers 35 as a percent of the incident light. The photochromic element may be associated with a fiber 35 as a coating applied to the outer surface of a fiber 35. Additionally, the light sensitive element may be incorporated directly into the material comprising the fiber 35. In the coating application, the coating may be applied through a method such as passing the fiber through a bath or may be co-extruded with the fiber 35 as an outer layer. As the light intensity increases, light absorption is impeded as a percent of incident light and as incident light intensity decreases, the light-sensitive element becomes more light transmissive and light absorptive as a percent of incident light thereby providing a more constant light output at the sighting end 33 of a fiber 35.
The fibers 35 are self-regulating to maintain a more substantially constant level of light being transmitted from the end of the fiber-optic fiber 35 whereby tuning of a fiber is improved for a wider spectrum of impinging light. As the incident light changes in intensity or color, the light sensitive element automatically regulates light output from an end 33. As one or more components of incident light changes, such as by increasing, light absorbed correspondingly changes by decreasing.
Thus, there has been shown and described several embodiments of a novel invention. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms “having” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required”. Many changes, modifications, variations and other uses and applications of the present construction will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow. While it is believed that the theories advanced herein regarding light absorption and transmission are correct, applicant is not bound thereby.
