Abstract:
A bow string release for engaging and releasing a bow string, comprising opposing jaws, a trigger, a housing, a jaw roller and a plurality of pins, the opposing jaws and the trigger coupled to the housing by pins, and the jaw roller coupled to the trigger and allowing the opposing jaws to an open condition when the trigger is in a pulled position. The bow string release of the present invention is adapted to minimize “loading up” of trigger force required to pull the trigger at full draw of a bow. Further the bow string release of the present invention is adapted to release the bow string at a trigger pull force of equal to or less than 9 ounces when an effective draw weight of the bow is equal to or more than 15 pounds.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is generally related to a bow string release and is specifically directed to a release head. 
     2. Description of the Prior Art 
     Mechanical archery bow string releases have become increasingly popular in recent years because they provide uniform control of the bow string and increase accuracy by effecting the consistent, controlled release of the arrow. Bow string releases are typically used to maintain the bow string in a cocked position in which the bow string is flexed against the tension of the bow for propelling the arrow supported on the bow string. When a drawn arrow is released from a release mechanism, the release is usually relatively rapid and at a point approximately in line with the centerline of the bow so that the bow string delivers most of its thrust directly along the major axis of the arrow. When tabs or fingers are used to release a bow string, the bow string tends to roll off the fingers or tab and be deflected sideways during release such that the bow string follows a serpentine path, failing to maximize energy delivery directly along the major axis of the arrow. 
     The arrow itself is generally comprised of a shaft with a point mounted on one end and a nock mounted on the opposite end. A standard arrow nock has a bow string receiving groove or notch defined by spaced apart legs extending from a base. The nock is configured to receive a bow string and insure stability of the arrow when the bowstring is drawn and released. When an arrow is loaded on a bow in this manner, the legs of the arrow nock extend beyond the bow string toward the archer such that and arrow can rotate about the bow string. When engaging the bow string, the nock is preferably seated at or near the mid-pint of the bow string to insure that the flight of the arrow is as true as possible. 
     The majority of the bow string releases have a body or casing which houses the sear and trigger mechanisms. The body is typically a cylindrical or rectangular design with the pivotable jaws of the sear mechanism positioned at one end and a trigger located along the length of the body. The release employs a trigger mechanism to activate the bow string retaining and release mechanism. The jaws and trigger mechanism of the bow string release are traditionally secured to the body with linkages or pins, which serve as a pivot mechanism for the jaws and trigger. 
     Recently, receivers for bow string releases have become increasingly popular. One example of such a receiver is disclosed in U.S. Pat. No. 5,850,827, assigned to Tru-Fire Corporation. When using a receiver, the archer attaches the bow string release directly to the receiver, instead of to the bow string. Instead of releasing the bow string, the release grasps and releases the receiver, which in turn allows the string to advance and propel the arrow forward. 
     Rope loops are also used in this capacity as a receiver. A short piece of rope, ordinarily approximately 2 mm in diameter, is attached to the bow string both above and below where the arrow nock rests. The perceived advantages of using a rope loop are varied. Once an archer employs a rope loop, the archer may find that it is difficult to engage the bow string release with the rope loop, due in part to the very resilient nature of rope. 
     Because of the difficulty in attaching bow string releases to rope loops, different bow string releases adapted to more easily grasp rope were introduced, including that disclosed in U.S. Pat. No. 5,680,851 to Summers, which is incorporated herein by reference. Other bow string releases adapted to more easily grasp rope include the Tru-Fire Corporation&#39;s “Tru-Caliper” line of releases. 
     Draw weight of a bow is ordinarily measured in pounds, and is the force required to pull back a bow string from a static position to a full draw position. Effective draw weight of the bow is the draw weight after let-off is factored. Effective draw weight is the force required to hold the bow string at full draw in the firing position. Common bows have draw weights of up to 100 pounds, and let-offs of up to 80%, decreasing the draw weight that the archer feels at full draw by the let off percentage. 
     It has been found that many commercial bow string releases, including a release referred to as a Tru-Ball “Tornado” release, “load up” severely as pulling force on the bow string is increased. “Loading up” is a phenomenon whereby the force required of the archer to pull the trigger and release the bow string increases as the effective draw weight of the bow increases. Thus, at higher effective draw weights, the archer must pull harder on the trigger, perhaps causing a decrease in sensitivity and performance. A harder trigger pull may also cause a jerking trigger release motion, causing erratic arrow flight. 
     There are two common trigger sensitivity adjustment mechanisms used widely. In one mechanism, the depth of engagement of sear elements is varied. This affects trigger pull length, also known as trigger travel distance, and indirectly affects pull force required by making the trigger travel farther to disengage the sear, which in turn increases the sliding friction. An example of this mechanism is U.S. Pat. No. 5,680,851 to Summers. 
     Another mechanism is a single roller on one sear element, sear element, typically mounted on one jaw, positioned in an angled slot in the other sear element, typically a slot in the trigger. Examples include a release known as the Scott Caliper release. In this mechanism, a roller is used to reduce friction between the sear elements. Adjustment is related to the positioning of a roller&#39;s center in relation to the edge of the angled slot. This limits the upper end range of trigger force required due to the rolling force in the slot. At the lower end of the pull force range, the roller center is balanced on or just outside the slot edge. If the roller center is outside the slot edge, the release will not stay closed during bow draw unless a force is applied to overcome the center over the edge condition created. 
     The only known release that changes the angle of contact between sear members and therefore permits incremental linear adjustments of trigger force is Tru-Fire&#39;s Classic Caliper as described in U.S. Pat. No. 5,582,158. 
     SUMMARY OF THE INVENTION 
     The present invention provides a bow string release mechanism that is easily attached to a bow string or a receiver. An archer&#39;s index finger pulls the bow string release of the present invention to open jaws on the release, and relaxes tension on the trigger to close the jaws. The jaws can be closed around a bow string, a receiver or the like. This convenient system allows the archer to maintain one finger on the trigger of the release to load the release onto the bowstring or receiver, and to relax the trigger to finalize loading by closing the jaws of the release. 
     The same trigger is used to release the bow string from full draw to propel the string and the arrow. 
     In one embodiment, the trigger is separated from the jaw to allow for smoother operation at all trigger sensitivity settings, particularly at fastest or lightest settings. In this embodiment, the trigger is not an integral sear element, and transmission of forces and slight movements are transferred to a roller axle linkage assembly from the jaws. This allows for reliable lower trigger settings. 
     It has been found that bow string releases according to the present invention advantageously minimize “loading up,” thereby minimizing the force required of the archer to pull the trigger and release the bow string as the effective draw weight of the bow increases. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view, with portions broken away, of a bow string release in a closed condition. 
     FIG. 2 is a cross-sectional view, with portions broken away, of a bow string release in an open condition. 
     FIG. 3 is a cross-sectional view, with portions broken away, of a bow string release. 
     FIG. 4 is an orthogonal view of a caliper jaw. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The string release of the present invention is shown on in FIG.  1  and is designated generally by the numeral  5 . The release includes a body or housing which carries the trigger mechanism and a head. 
     The bow string release  5  of the present invention has been found to perform extremely advantageously when compared to releases such as a commercial embodiment of what is disclosed in U.S. Pat. No. 5,680,851 to Summers. 
     As shown in Table 1 and Chart 1 below, it has been found that prior art bow string releases, such as the commercial embodiment of U.S. Pat. No. 5,680,851 to Summers, “load up” severely as pulling force on the bow string is increased. “Loading up” is a phenomenon whereby the force required of the archer to pull the trigger and release the bow string increases as the effective draw weight of the bow increases. “Loading up” is not desirable because of the detrimental effects described previously, including detrimental effects on arrow accuracy and release durability. 
     
       
         
               
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
             
             
               
                   
                   
               
               
                   
                 Effective Draw Weight (in pounds) 
               
             
          
           
               
                   
                 0 
                 15 
                 25 
                 30 
                 40 
                 50 
                 100 
               
               
                   
                   
               
             
          
           
               
                 Trigger Force Required 
                   
                   
                   
                   
                   
                   
                   
               
               
                 to Release Jaws 
               
               
                 (in ounces) 
               
               
                 Commercial embodiment 
                 8 
                 21 
                 32 
                 34 
                 46 
                 &gt;50 
                 &gt;50 
               
               
                 of U.S. Pat. No. 
               
               
                 5,680,851 to Summers 
               
               
                 out of the box 
               
               
                 Commercial embodiment 
                 9 
                 10 
                 14 
                 12 
                 18 
                 &gt;50 
                 &gt;50 
               
               
                 of U.S. Pat. No. 
               
               
                 5,680,851 to Summers 
               
               
                 (lightest adjustment) 
               
               
                 Present Invention at 
                 3.5 
                 6.2 
                 9.8 
                 12 
                 14 
                 18 
                 50 
               
               
                 average setting 
               
               
                 Present Invention at 
                 3 
                 5.5 
                 5.6 
                 5.9 
                 9.2 
                 9.3 
                 19.8 
               
               
                 lightest setting 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
             
           
               
                 CHART 1 
               
               
                   
               
             
             
               
                 
                   
                             
                     
                         
                         
                     
                   
                 
               
               
                   
               
             
          
           
               
                 
                   
                             
                     
                         
                         
                     
                   
                 
                 Commercial embodiment of U.S. Pat. No. 5,680,851 to Summers out of the box 
               
               
                 
                   
                             
                     
                         
                         
                     
                   
                 
                 Commercial embodiment of U.S. Pat. No. 5,680,851 to Summers (lightest adjustment) 
               
               
                 
                   
                             
                     
                         
                         
                     
                   
                 
                 Present Invention at average setting 
               
               
                 
                   
                             
                     
                         
                         
                     
                   
                 
                 Present Invention at lightest setting 
               
               
                   
               
             
          
         
       
     
     In contrast to prior art releases, the release  5  of the present invention requires a trigger pull force of less than fifty ounces, even less than ten ounces to separate jaws  20  of the release  5 , even at an effective draw weight of one hundred pounds. 
     Referring now to FIG. 1, the release  5  is shown with a body or housing  90 , which is a well known component in the art and can vary widely. The housing  90  is shown with most portions cut away to simplify the description of the mechanical components of the present invention that ordinarily, but not necessarily reside with the housing  90 . 
     The release  5  is shown in FIG. 1 in a closed or string retaining position, shown holding string  10 , which can be a bow string, a receiver, a rope loop, or any other object desired to be released. A string retaining void  12  is provided as opposing openings on two opposing jaws  20  to receive the string  10 . 
     When an archer pulls on a trigger  40 , jaws  20  are separated at a portion of the jaws  20  closest to the string  10 . The mechanism that separates the jaws  20 , and also keeps the jaws  20  together at rest at the portion of the jaws  20  closest to the string  10 , is a cooperation between components in the release  5 , as will be described fully below. 
     The trigger  40  is coupled to an axle link  60 , in turn coupled to a jaw roller  50 . At rest, a reset spring  80  urges the trigger  40 , and in turn the axle link  60  and the jaw roller  50 , towards the string  10 . The reset spring  80  is placed between the trigger  40  and a reset spring support  85 . 
     It should be noted that although we have chosen to call the jaw roller  50  a roller, the jaw roller  50  may not roll at all in the present embodiment because the jaw roller  50  is being acted upon equally but in opposite directions by both jaws  20 . Instead of rolling, the jaw roller  50  provides a surface for which the jaws  20 , and particularly the portion of the jaws  20  nearest to the closed condition roller receiver  52 , roller receiver ridges  53 , and the open condition roller receivers  54 , to slide along during rotation of the jaws  20  between open and closed positions, and also during travel of the jaw roller  50  away from the string  10 . 
     The jaw roller  50  is preferably a cylindrical body to decrease friction, although a wide variety of other forms could also perform suitably, such as but not limited to spherical elements such as ball bearings, non-spherical elements, or non-rotating members. For the purpose of defining the claims, although a roller is referred to, a roller is a surface for which the jaws  20 , roller receiver ridges  53 , and the open condition roller receivers  54 , slide along during rotation of the jaws  20  between open and closed positions. 
     At rest, the jaw roller  50  is urged to contact and reside at least partially within a pair of opposing closed condition roller receivers  52 . The closed condition roller receivers  52  are surfaces on interior portions of opposing jaws  20 . 
     At rest, a portion of the jaws  20  furthest away from the string  10 , the jaws are pushed away from each other by the jaw roller  50 . This urges the jaws  20  to remain closed at the portion of the jaws  20  closest to the string  10 . 
     A pin  55  is provided to couple the trigger  40  with the body  90 , and also to provide a pivot point about which the trigger  40  is allowed to rotate during pulling of the trigger  40  and during return of the trigger  40  to the at rest position. Similar pins  55  are provided to couple the jaws  20  to the body  90 , and also to provide a pivot point about which the jaws  20  are allowed to rotate. 
     A jaw spring  30  is provided between jaws  20  to urge the jaws  20  apart at a portion of the jaws  20  closest to the string  10  when it is desired to separate open the jaws  20 , as will be discussed later. The jaw spring  30  is retained between jaws  20  in opposing jaw spring receivers  32  provided on the jaws. 
     A preferable construction detail of the jaws  20  is that the jaws are provided with a tab  42  and a socket  44  as shown. A similar tab and socket arrangement is fully described in U.S. Pat. No. 5,357,939 which is incorporated herein by reference. The tab  42  and socket  44  of the present invention synchronize the jaws by providing contact points between pins  55  that couple the jaws  20  with the body  90 . This tab  42  and socket  44  arrangement prevents jaws  20  from undesirable swiveling motion during release  5  operation. Each opposing jaw  20  preferably has a tab  42 , that can fit within a socket  44  on the opposing jaw. Independent ball bearing elements would also prevent the swiveling motion. 
     An adapter  100  is provided to couple the release  5  to other components that are not shown, such as a shaft or a release body structure. For example, but not by way of limitation, release body structures comprise hand-held or wrist strap style releases, such as a Tru-Fire BearPaw® release, a release known commercially as Winn Free Flight release, a Cobra Armstrong type glove, wrist strap styles such as used on a Tru-Fire Storm release (not shown) or a strap described in U.S. Pat. No. 4,831,997 to Greene, and hand-held styles (not shown). The release  5  of the present invention may be attached to any structure by any means, and the means for securing the release  5  to other components is not a part of the present invention. 
     Referring now to FIG. 2, the release  5  is shown in an open or string releasing position, shown with string  10  not gripped by the jaws  20 . 
     To either engage the string  10  or release the string  10 , an archer pulls on the trigger  40 . When the trigger  40  is pulled, the trigger  40  draws the axle link  60  and the jaw roller  50  away from the string  10 , and also compresses the reset spring  80 . The trigger  40  is rotated around an axis pin  55 , the use of which to secure components in a bow string release is well known. When the trigger  40  is pulled away from the string  10 , the axle link  60  and the jaw roller  50  travel generally away from the string  10 , allowing the jaw roller  50  to slide past a roller receiver ridge  53  that separates the closed condition roller receivers  52  from opposing open condition roller receivers  54 . 
     Roughly simultaneously, the jaw spring  30  urges the jaws  20  to open closest to the string  10  in the open or string releasing position. 
     Referring now to FIG. 3, it is preferable to provide a trigger sensitivity adjustment screw  70  on the release  5  in order to allow archers to increase or decrease the trigger force, and/or trigger travel distance required to release the jaws  20 . The screw  70  passes through a threaded void (not shown) in the trigger  40 . 
     In a preferable commercial construction detail, the screw  70  is tightened with a small socket wrench by accessing a socket head (not shown) carried by the screw  70  toward the frontward (or left end when viewing FIG. 3) portion of screw  70 . 
     In this embodiment, an archer can tighten or loosen the screw  70  when the trigger  40  is in the open, string releasing condition. The screw abuts against a portion of the jaw  20 . By loosening the screw  70 , more of the screw  70  becomes exposed toward the frontward portion of the screw  70 , decreasing the trigger travel distance. By tightening the screw  70 , less of the screw  70  is exposed, increasing the trigger travel distance. 
     An imaginary line is drawn between roller receiver ridges  53 , and designated as line  53 ′. Also shown is a centerline of jaw roller  50 , designated as centerline  50 ′. The distance between  50 ′ and  53 ′ is designated as the engagement distance. In a commercially preferable embodiment, a construction detail of the engagement distance is that the maximum engagement distance is 0.014″. 
     If the screw  70  is fully tightened, the engagement distance is the greatest. The distance that an archer must pull the trigger  40  rearward (to the right when viewing FIG.  3 ), also referred to as trigger travel distance, is maximized. If the screw  70  is loosened, the engagement distance can be minimized, and the lighter trigger settings shorter trigger travel distances are achieved. In the fully loosened screw  70  position, trigger travel distance is minimized, with a commercially preferable minimum of just slightly greater than 0″. 
     When an archer pulls on the trigger  40  and pulls centerline  50 ′ past line  53 ′ (rearward, or to the right when viewing FIG.  3 ), the jaw roller  50  slides down into the open condition roller receiver  54 . 
     Referring now to FIG. 4, an orthogonal view of a single jaw  20  is shown, although it is understood that two similar opposing jaws  20  are employed on the release  5 , with similar mirroring structure. The opposing jaws preferably each have a opposing tab  42 , that can fit within a opposing socket  44  on the opposing jaw. Also preferably, each opposing jaw  20  has a face surface  22 , although any suitable string retaining arrangement could be used. 
     Preferably, closed condition roller receivers  52  as shown on FIGS. 1-3 are formed by closed condition roller receiver angle surface  52   a  and closed condition roller receiver parallel surface  52   b  as shown on FIG.  4 . Also preferably, open condition roller receivers  54  as shown on FIGS. 1-3 are formed by open condition roller receiver angle surface  54   a  and open condition roller receiver parallel surface  54   b  as shown on FIG.  4 . Open condition roller receiver angle surface  54   a , in conjunction with spring  30  and reset spring  80  (shown in FIGS. 1-3) maintain constant contact with the roller  50  during firing, preventing undesirable clicking and minimizing component wear. 
     It should be noted that the open condition roller receivers angle surface  54   a  form a relatively steep slope to slide about the jaw roller  50 , compared to a relatively parallel relationship formed by the closed condition roller receiver parallel surfaces  52   b . Although we have referred to some surfaces as parallel, parallelism is not required, it is a preferred relationship for ease of fabrication. 
     A sensitivity screw abutting surface  55  is provided for either the screw  70  or the trigger  40  (shown in FIGS. 1-3) to rest against. 
     Roller receiver ridge  53 , shown in FIGS. 1-4, provides a transition between surfaces that maintain closed string retaining condition and open string releasing condition. A preferred embodiment of roller receiver ridge  53  has a small radius, although a sharp edge would also perform suitably. 
     Turning to materials used to construct the components of the release  5 , it has been found that a decrease in friction between components such as the roller  50  and jaws  20  minimizes wear. By providing frictionally compatible materials between components of the release, wear is minimized, which is advantageous to long term function of the release  5 . 
     One approach to decreasing friction and minimizing wear is to use like material to construct both the roller  50  and jaws  20 . Like materials that are frictionally compatible and perform suitably are steel to construct both the roller  50  and jaws  20 . The coefficient of rolling friction for steel on steel or iron on iron is reported as 0.02, a highly acceptable level. 
     Another approach to decreasing friction and minimizing wear is to use material to construct both the roller  50  and jaws  20  that possess low coefficients of static friction. For example, Teflon® coated material may have coefficients of static friction as low as 0.04, again a highly acceptable level for a frictionally compatible material. 
     The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials, and components, as well as in the details of the illustrated construction may be made without departing from the spirit of the invention.