Laser sight for hunting bow

A laser sight with automatic angle compensation for bow hunting from tree platforms, comprising a box with open front and back ends attached to a bow handle. A laser pointer is pivotally mounted in the sight box. A cam operated by a pendulum moves the laser pointer to compensate the laser beam direction for different shot distances by detecting the vertical angle of the bow. The higher the bow is aimed, the lower the laser beam is aimed relative to the bow to compensate for the greater drop of the arrow over greater distance. A second pendulum in the sight box operates a peep pin for use with a conventional peep sight on the bowstring. The peep pin maintains an angle via its pendulum that guides the archer's line of sight to the laser spot, allowing the archer to visually acquire the spot quickly even during daylight. The laser beam and peep pin are coordinated via adjustments that are independent of each other and independent of cam or pendulums.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention is in the field of sights for hunting bows, especially laser 
sights. 
2. Description of Prior Art 
Laser sights are available for hunting bows, as shown in the prior patent 
discussed below. However, they lack features provided by the present 
invention. Simple laser pointers with beam direction adjustments are 
available, but each setting only applies to a specific target distance and 
angle of the bow. The curvature of an arrow's trajectory depends on the 
vertical angle of the shot--the higher the shot, the greater its 
curvature. Bow hunters commonly shoot from platforms about 3-9 m (10-30 
ft) high in trees. From this position, the angle of a shot is normally 
about 20-60 degrees downward from horizontal. The bow angle and distance 
to a target are closely related, especially on flat terrain. Thus a bow 
sight can theoretically compensate for changes in the distance based on 
the angle of the bow, as detected by a pendulum. 
U.S. Pat. No. 5,782,002 (Reed) discloses a "Laser Guidance Means", 
comprising a pivotally mounted laser pointer 46 that rests on an offset 
cylindrical cam 52. The cam is mounted on a pendulum 60. The cam is 
attached to the pendulum by a screw 54 that moves the cam vertically for 
vertical adjustment of the laser beam. However, any vertical adjustment 
also changes the eccentricity of the cam from its pivot point 66. This 
dependency is undesirable. In Reed's patent drawings, the cam is offset 
upward from the pivot point 66, so its apex is the top of the cam. This is 
counterproductive. When the bow is aimed horizontally as in FIG. 5, Reed's 
laser will be aimed highest relative to the bow, but the arrow will fall 
lowest due to the longer flight distance and maximum gravity effect on the 
trajectory. Thus the setting shown in Reed will compensate in the opposite 
direction to what is needed, making it less accurate than a fixed laser 
pointer. Reed's cam can be moved lower, so that its geometric center is 
below the pendulum pivot axis. Then it will compensate in the right 
direction, but the magnitude and rate of compensation is dependent on the 
vertical setting. For example, when the required vertical setting places 
the geometric center of the cam coincident with the pendulum pivot axis, 
the cam eccentricity is zero, eliminating compensation entirely. There is 
no way in Reed to maintain a correct cam offset independently of the 
vertical setting. 
In daylight a laser spot is hard to find when sighting. It is only a small 
dim spot distantly reflected by the camouflage colors of nature among 
dapples of sunlight. In a pendulum-compensated sight, the laser spot is 
not along a fixed line, so a simple mechanical peep sight is not 
sufficient to find it. Thus a peep sight that follows the moving laser 
spot is needed. 
SUMMARY OF THE INVENTION 
The objectives of the present invention are the provision of a laser sight 
for bows that automatically compensates for the angle of the bow via a 
pendulum-operated cam, that has a mechanical sight that follows the laser 
spot for visually acquiring the laser spot in daylight, and that has laser 
aim adjustments that are independent of the cam and the mechanical sight 
adjustments. 
These objectives are achieved in the present laser sight using a laser 
pointer in a case with aim adjustment screws. The laser pointer is 
pivotally mounted in a sight box having open front and back ends. A cam 
operated by a pendulum moves the laser pointer to compensate for changing 
shot distances by detecting the vertical angle of the bow. The higher the 
bow is aimed, the lower the laser beam is aimed relative to the bow, to 
compensate for the greater drop of the arrow over a greater target 
distance. A second pendulum in the sight box operates a peep pin for use 
with a conventional peep sight on the bowstring. The peep pin maintains an 
angle via its pendulum that guides the archer's line of sight to the laser 
spot, allowing the archer to find the spot quickly even during daylight.