Geometrical instruments – Straight-line light ray type – Structurally installed
Reexamination Certificate
1998-11-04
2002-07-16
Bennett, G. Bradley (Department: 2859)
Geometrical instruments
Straight-line light ray type
Structurally installed
C124S087000
Reexamination Certificate
active
06418632
ABSTRACT:
TECHNICAL ART
The instant invention generally relates to projectile launcher sights which compensate for both the range to the target and the elevation of the shooter relative to the target. More particularly, the instant invention relates to sights for those projectile launchers such as archery bows for which such compensation is necessary.
BACKGROUND OF THE INVENTION
A projectile launcher launches a projectile at a target at which the shooter aims using a sight. The projectile launched by the projectile launcher follows a ballistic trajectory towards the target, which trajectory is influenced by forces of gravity and drag. The projectile launcher must accordingly be aimed so as to cause the projectile to be launched on a trajectory intersecting the target. The degree to which the initial direction of the projectile differs from the associated straight line path to the target is dependent upon the distance to the target and the degree of influence of gravity or drag upon the projectile, whereby this difference is greater for projectiles launched at relatively lower velocities or which have relatively higher amounts of drag. For example, archery bows, cross bows, sling shots, and low power rifles, such as air rifles, are all subject to significant influences of gravity and drag upon the trajectory of their associated projectiles.
The purpose of the sight on the projectile launcher is to enable the shooter to align the projectile launcher by aiming the sight on the target so as to cause the trajectory of the projectile to intersect the target. For example, when an arrow is shot from an archery bow the departure of the trajectory of the arrow from a straight line can be significant, particularly for distant targets, which requires a means in the associated bow sight to compensate for target range. The departure of the arrow trajectory from a straight line generally depends upon the range to the target and the elevation of the archer relative to that of the target.
More particularly, in the field of archery, an elementary bow sight comprises a single fixed pin, whereby the archer aims the bow by aligning the pin with the target. By maintaining a consistent draw of the bow and a consistent placement of the knock of the drawn arrow relative to the archer's eye the trajectories of similarly aimed shots can be made consistent. The problem with a single fixed pin however is that the sight will be properly aimed for only one mode of operation of the bow, i.e. for a limited range of target ranges and a limited range of shooting elevations relative to the target elevation.
The prior art teaches a bow sight assembly comprising a plurality of fixed pin sights, each of which is calibrated for a different target range, or combination of target range and shooting elevation relative to the target elevation. However, one disadvantage of such a sight assembly is that each of the fixed pins must be separately calibrated. Furthermore, there is a potential for the archer to use the wrong pin for aiming at the target.
The prior art also teaches a bow sight assembly comprising a mechanism for adjusting the position of either a single pin sight, or a multiple pin sight assembly, or a cross-hair attached at a sight attachment point, in accordance with the range to the target. This type of sight also has the disadvantage of needing to be calibrated for each of the various modes of operation of the bow. Furthermore, the associated mechanism can be expensive and difficult to produce, and difficult to operate properly under conditions of low ambient lighting or when wearing gloves. Examples of this type of sight are disclosed in U.S. Pat. Nos. 2,669,023, 3,487,548, 3,568,323, 3,718,979, 3,787,984, 4,162,579, 4,224,741, 4,368,581, 4,532,717, 4,541,179, 4,643,160, 4,726,123, 5,001,837, 5,092,052, 5,359,780, 5,419,051, 5,465,491 and 5,524,601. While these patents teach various mechanisms for adjusting the height of a sight attachment point, none of these patents teach or suggest the incorporation of a pendulum sight subassembly at the sight attachment point.
The prior art also teaches the use of a combination of front and rear sights, or a telescope having a sighting axis, so as to improve shooting accuracy. However, these sights also require a means for adjustment and calibration to accommodate different ranges and elevations of the archer relative to the target. Examples of this type of sight are disclosed in U.S. Pat. Nos. 2,559,927, 2,667,692, 2,982,026, 3,058,221, 3,063,151, 3,271,863, 4,237,615, 4,417,403, 4,418,479, 4,625,420, 4,961,265, 5,040,300, 5,048,193, 5,092,053 and 5,539,989. While these patents teach various mechanisms for adjusting the orientation of either a combination front and rear sights, or a telescope having a sighting axis, none of these patents teach or suggest the incorporation of a pendulum sight subassembly with such mechanisms.
Another type of archery bow sight taught in the prior art, and in common use, is referred as a pendulum bow sight, which comprises a pendulum having center of gravity and a pivot point located thereabove. The pendulum pivots about one end of a pivot shaft which axis passes through the pivot point, and the other end of the pivot shaft is secured to the archery bow at the sight attachment point. The pendulum is biased so that the center of gravity of the pendulum remains directly below the pendulum pivot point—the pendulum stays in a vertical position—regardless of the elevation angle of the archery bow. A sight aiming point is attached to or incorporated on the pendulum. In some commercially available pendulum bow sights, the pendulum is constructed from a rod which incorporates the sight aiming point at the upper end. The pendulum is further provided with a counterweight, a means for adjusting the relative length of the pendulum above the pivot point, and a means for adjusting the position of the counterweight along the lower length portion of the pendulum. In operation, for a target elevation which differs from the elevation of the archer's eye, the angle of the ray projected from the archer's eye to the target changes with the range of the target relative to the archer. Therefore, targets of differing ranges cause the archer to incline the bow at correspondingly different angles in order to align the bow sight with the target. The pendulum remains vertical independent of the elevation angle of the archer's bow, so that the position of the sight aiming point changes relative to the projectile launcher. More particularly for a target below the eye level of the archer, as the target range is increased, the archer must raise the bow in elevation angle to keep the sight aiming point aligned with the target. As the elevation angle of the bow is increased, an associated automatic rotation of the pendulum causes the projected distance between the sight aiming point and the arrow to decrease, which thereby causes the archer to raise the bow in elevation angle more that would have been raised had the sight aiming point been fixed. Therefore, the pendulum sight inherently provides compensation for target range so as to enable the archer to shoot accurately over a range of target ranges. The pendulum bow sight is particularly useful for automatically compensating for target range when shooting from elevated platforms. However, a pendulum bow sight calibrated for shooting from an elevated platform, such as a tree stand, will not be calibrated for shooting from ground level. More particularly, the pendulum bow sight must be calibrated for the conditions of relative elevation between target and shooter under which the sight will be used.
Examples of pendulum bow sights are disclosed in U.S. Pat. Nos. 2,925,656, 3,013,336, 3,521,362, 4,120,096, 4,580,349, 4,616,422, 4,711,036, 4,720,919, 4,794,702, 4,894,921, 4,974,328, 5,121,547, 5,253,423, 5,305,530, 5,347,722 and 5,561,910. While these patents teach various pendulum bow sight assemblies, and disclose a means for adjusting the height of the pendulum sight assembly for calibration thereof, whereby
Apik Enterprises, Ltd.
Bennett G. Bradley
Van Voorhies Kurt L.
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