Abstract:
A projectile that includes a vibrating function is presented. The vibrating projectile, such as an arrow, is structured to penetrate flesh of an animal more easily than a standard projectile. After the arrow has reached its target, a switch turns on a vibrating mechanism that causes the arrowhead, such as a broadhead to vibrate as it is traveling into the animal. This deeper penetration causes more injury to the animal and reduces the time between arrow penetration and animal expiration.

Description:
FIELD OF THE INVENTION 
     This disclosure is directed to projectiles, and, more particularly, to projectiles having a vibrating feature as they enter their target. 
     BACKGROUND 
     Hunting is an ancient tradition that is still practiced for both survival and sport. In both cases the hunter&#39;s goal is to harvest the animal as humanely and quickly as possible. 
     While hunting using firearms is the most common form of hunting, especially when hunting big game such as elk and deer, hunting using a bow and arrow remains a popular activity. Bow hunters enjoy the increased challenge of hunting an animal using primarily mechanical means. In other words, it can be more physically challenging to harvest animals using a mechanically launched projectile, such as an arrow, than it is when using a firearm that accelerates its projectile as a result of a controlled explosion, often with the aid of ancillary sighting devices which can provide increased long range accuracy. This difference, however, can pose a problem because it can be more difficult to bring down an animal as efficiently with an arrow as it is with a bullet. 
     The archery industry has strived to increase the killing force of the bow and arrow system with various improvements. For instance, bows were made with stronger pulling force, which resulted in the arrow being launched with higher velocity. The higher velocity translates to more damage done by the arrow, which results in quicker, more efficient harvesting of animals. When bows approached the limit of not being able to be effectively drawn and held by the archer, compound bows were developed that created additional mechanical force by using cams or lobed pulleys in conjunction with the bow and bowstring. Because of their let-off, these compound bows can have increased launching force and the ability to hold the bow at full draw for precision targeting with the use of a bow sight. Compound bows are now the most common bow used in hunting, especially big game hunting. 
     Arrows and especially arrowheads have also changed over time to increase the likelihood that the animal is quickly brought down. Broadheads have evolved from the stone heads of ancient times to the current broadheads made of metal. Generally broadheads have two to four fixed blades which may be finely sharpened to deeply penetrate the animal and cause massive internal bleeding. This minimizes the time between arrow penetration and animal expiration. Further, if the arrow does not kill quickly enough, the animal may travel significant distance after it is struck, increasing the likelihood that the animal may not be recovered, or that the animal unnecessarily suffers before dying. 
     Mechanical broadheads may also be used by hunters. Mechanical broadheads have two positions, a retracted position for flight and a second position that is deployed after the arrow strikes the animal. When the arrow strikes the animal, the broadhead switches from the flight position to the strike position, exposing its blades, which causes more damage to the animal than if the broadhead remained in the flight position. Mechanical broadheads generally penetrate the animal less deeply than fixed broadheads because some of the kinetic energy of the arrow is used to release the mechanical broadhead, although the increased damage to the animal that a mechanical broadhead causes may outweigh the kinetic energy loss, as they can have greater flight aerodynamics in the retracted position and a larger diameter cutting capability in the fully deployed open position upon impact with targeted animal. 
     Mechanical broadheads do not always work as intended, however. Depending on such variables as velocity, arrow weight, strike location, strike angle, etc., the mechanical broadheads may not fully deploy their mechanical blades or they may use too much of the arrow&#39;s kinetic energy to cause sufficient damage to the animal to bring it down quickly and humanely. In these cases it may have been better to use a fixed broadhead rather than the malfunctioning mechanical broadhead. The hunter does not know before the arrow strike, however, whether the mechanical or fixed broadhead would have been better for the particular shot. Lack of penetration has been cited as a significant factor in non-lethal shots which are, of course, to be avoided. 
     Embodiments of the invention address these and other limitations of the prior art. 
     SUMMARY OF THE INVENTION 
     Aspects of the invention include a projectile, such as an arrow, that includes an elongated shaft and a cutting head coupled to the shaft. Further included is a vibrator structured to vibrate the cutting head after the projectile strikes a target. The vibrator may be controlled by a switch, which may be a mechanical or acceleration switch. The switch may change states as the arrow strikes its target. The vibrator may be located anywhere within the arrow system, such as the nock, shaft, threaded insert, or the cutting head of the projectile. The switch may be co-located with the vibrator, or may be located between components of the arrow. The vibrator may be an electric motor, or may be powered by a mechanical spring, or by other means. Embodiments are also directed to a broadhead including a vibrator function, a threaded insert including a vibrator function, and an arrow shaft including a vibrator function. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of an arrow having a vibrator according to embodiments of the invention. 
         FIG. 2A  is a partial side view of an arrow illustrating an arrow in a flight position according to embodiments of the invention. 
         FIG. 2B  is a partial side view of the arrow of  FIG. 2A  illustrating the arrow in a position that enables a vibrating function of the arrow according to embodiments of the invention. 
         FIG. 3A  is a partial side view of a broadhead illustrating the broadhead in a flight position according to embodiments of the invention. 
         FIG. 3B  is a partial side view of the broadhead of  FIG. 3A  illustrating the broadhead in a position that enables a vibrating function of the broadhead according to embodiments of the invention. 
         FIG. 3C  is a partial side view of another broadhead illustrating the broadhead in a flight position according to embodiments of the invention. 
         FIG. 3D  is a partial side view of the broadhead of  FIG. 3C  illustrating the broadhead in a position that enables a vibrating function of the broadhead according to embodiments of the invention. 
         FIG. 3E  is a partial side view of a mechanical broadhead illustrating the broadhead in a closed position according to embodiments of the invention. 
         FIG. 3F  is a partial side view of the broadhead of  FIG. 3E  illustrating the broadhead in an open position according to embodiments of the invention. 
         FIG. 4  is a side view of an arrow shaft having a threaded insert therein that includes a vibrating mechanism according to embodiments of the invention. 
         FIGS. 5A ,  5 B,  5 C, and  5 D are side views of example blades of a broadhead shaped to maximize vibrational energy transferred to the cutting blades according to embodiments of the invention. 
         FIG. 6  is a side view of a vibrating mechanism for a projectile according to embodiments of the invention. 
         FIG. 7  is an isometric drawing of a vibrating motor used in embodiments of the invention. 
         FIG. 8  is a side view of a broadhead including a vibrational resonance chamber according to embodiments of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Penetration of a projectile such as an arrow into a game animal is dictated by factors such as the amount of kinetic energy retained by the arrow at impact, the time over which such energy is dissipated into the animal, the trajectory of the arrow, and the point of entry into the animal, as well as the sharpness, shape, and orientation of the broadhead blades, for example. 
     This disclosure generally describes a projectile having a vibrating function to increase penetration of the projectile into the desired animal thereby increasing the size of the wound channel. The larger wound channel causes more trauma and can bring down the animal quicker than the smaller wound channel that would have been created without vibration. 
     In this disclosure the projectile is described with specific references to an arrow, however the projectile may be embodied in other forms, such as a spear, blowdart, crossbow bolts, etc. Additionally, the movement described in the projectile is described as vibration, which also includes or may additionally include reciprocation, oscillation, pulsation, rotation, agitation or other motion. 
     When an arrow separates from the bow as it is being launched, it holds the maximum amount of kinetic energy for its flight to the target. In other words, as the arrow travels to its target, it is continuously losing kinetic energy. The lost energy is mostly transferred to the air in the form of drag, which is a function of arrow speed as well as the size and shape of the arrow, including its shaft and fletching. The density of the air through which the arrow is flying is also a factor, with denser air producing more drag. The amount of kinetic energy transferred into the target is roughly equal to the initial kinetic energy of the arrow less the kinetic energy lost during flight. Some of the energy of the arrow may be lost to other factors as well, such as heat lost to the atmosphere and the animal, and the sound generated by the impact of the arrow. 
     When striking the target animal, the kinetic energy is transferred to the animal in the form of momentum, which is a measure of the energy applied from the force of the arrow to the animal over time. More specifically, the arrow momentum is the integral of the force applied to the animal over the time the force is applied. In more detail, the arrow momentum is applied to the animal through the broadhead of the arrow, which penetrates the animal by cutting, ripping, and tearing strands of its flesh and, possibly, bone and cartilage. The amount of penetration is dependent on the momentum of the arrow, which, as described above, is related to its energy and time the energy is applied. The penetration depth is also dependent on the resistance force of the animal, which is, of course, determined by the physical makeup of the animal itself. Bones may provide more resistance to arrow travel than muscle, for instance, which in turn may provide more resistance than organs or other tissue. This resistance is related to the sectional density of the target. 
       FIG. 1  is a side breakaway view of an arrow  10  having a vibrator according to embodiments of the invention. The arrow  10  includes a main shaft  20  upon which feathers or fletching  22  are mounted. The fletching  22  stabilizes the arrow  10  during flight. A nock  12  is attached to the main shaft and includes a recess  13  into which the bowstring is received for launching the arrow  10 . The nock  12  may also include an LED or other locating signal generating device, such as light or sound that may help the hunter trace the arrow during flight towards the target and also retrieve an arrow that either missed its target or has traveled completely through the target, or is still protruding from the targeted animal which has been struck and is being recovered. 
     A threaded insert  30  is inserted into the shaft  20  at the end opposite the nock  12 . The threaded insert  30  is typically made of metal such as aluminum and is held fast within the shaft  20 , by means such as glue (not shown) or held by merely a mechanical friction fit. Typically the threaded insert  30  includes an internally threaded receiver (not shown) into which threads  52  of a broadhead  50  may be received and tightened. The broadhead  50  may be metal and formed by metal injection molding, machining and/or multiple part assemblies. 
     A vibrator  60  is included within the arrow  10 . Although the vibrator  60  is illustrated as being within the shaft  20 , the vibrator may be disposed in any convenient location, such as the shaft  20 , the threaded insert  30 , the broadhead  50 , or even in the nock  12 . In some embodiments the vibrator  60  is completely contained within the arrow, but in other embodiments the vibrator may extend beyond an outer surface of the arrow  10 . Description of the vibrator  60  mechanism is provided below. Many details of the vibrator  60  may be dictated by its particular implementation. 
     In the most common embodiment, when the arrow  10  is launched from a bow (not shown), the vibrator  60  is in an OFF state, i.e., it is not vibrating. Once the arrow  10 , or any part of it, strikes a target, a switching mechanism turns the vibrator  60  to an ON state. The vibrator  60  causes the arrow  10 , and especially its broadhead  50 , to vibrate, reciprocate, oscillate, pulsate, rotate, agitate, or otherwise move. This movement amplifies the cutting ability of the broadhead  50  as it passes through the flesh/bone of the target animal, which allows for deeper penetration of the arrow  10 . The vibration motion may also increase the size of the wound channel and the damage therein. The vibration may also help the shaft slide through the wound channel with reduced frictional drag due to the vibrating action. As mentioned above, deeper penetration and a larger wound channel is desirable in hunting because it minimizes the time between arrow penetration and death of the animal. 
     In some embodiments the vibrator  60  is set to vibrate at a particular frequency, such as between 10 and 500 Hz, and more particularly between 150 and 225 Hz. One embodiment causes the broadhead  50  to oscillate at 170 Hz, which may be the most efficient frequency at causing the broadhead  50  to cut muscle/organs. 
     In other embodiments the vibrator  60  may be a mid-frequency vibrator set to vibrate at between 5 kHz and 15 kHz. In yet other embodiments the vibrator  60  may be an ultrasonic or near ultrasonic vibrator set to vibrate at between 15 kHz and 20 kHz. 
     Vibrational energy may be conveniently provided by a motor, described below, or could be provided in other forms. For example vibrational energy may be stored in a wound spring and, upon striking the animal, a switch releases the spring to unwind, releasing its energy. 
     The vibration of the arrow  10  may also be implemented to amplify the vibration of the broadhead  50  so as to maximize the cutting efficiency of the broadhead. 
       FIGS. 2A and 2B  are partial side views of a broadhead illustrating operation of a switching mechanism for controlling the operation of the vibrator  60  according to embodiments of the invention. In  FIG. 2A , the broadhead  50  is separated from being fully seated in the threaded insert  30  by a gap  34 . The gap  34  may be caused by a mechanically operated switch, a pin  35  of which is shown, that has physically separated ON and OFF states. Thus, when the gap  34  is present, the switch is in the OFF state, which controls the vibrator  60  to also be in the OFF state. 
     With reference to  FIG. 2B , after the broadhead  50  of the arrow  10  has struck a target, the switch is mechanically driven to the ON state by the broadhead  50  suddenly striking the target while the remainder of the arrow continues on its path until the gap  30  is eliminated and the switch turned ON, such as by moving its pin  35 . The switch then turns ON the vibrator  60  which, as described above, causes the broadhead  50  to be driven further into the animal than if no vibrator were present. The broadhead  50  may be held in place by small O-rings, snap-rings or other mechanical means. 
     The switch may also function to turn on the audible and/or visible locating signal in the nock  12  described above with reference to  FIG. 1 . In other embodiments the locating signal may be switched on by other means, such as an acceleration or physical switch located in the nock  12  itself. 
       FIG. 3A  is a partial side view of a broadhead  100  illustrating the broadhead in an OFF or flight position according to embodiments of the invention. Differently than in the embodiment of  FIG. 2A , the embodiment illustrated in  FIG. 3A  is a self-contained vibratory broadhead  100  that includes a vibrator  160  and a switching mechanism  115 . The broadhead  100  includes a positionable tip  112  that has two positions. It is illustrated in an open position in  FIG. 3A  and illustrated in a closed position in  FIG. 3B . When the tip  112  is in the open position of  FIG. 3A , including a gap  114 , the switching mechanism  115  is in an OFF state, and consequently the vibrator  160  is likewise off. When the tip  112  is in the closed position of  FIG. 3B , and the gap  114  is not present, then the switching mechanism  115  turns to an ON state, and consequently the vibrator is turned ON. This increases the cutting ability of the broadhead  100  as described above. The positional tip  112  may be held in place by small O-rings, snap-rings or other mechanical means. 
       FIGS. 3C and 3D  show an embodiment of a broadhead  120  that operates similarly to the broadhead  100  of  FIGS. 3A and 3B , except that a switching mechanism  135  is controlled by a position of a relatively small sharp-tipped pin  126  located near the top of the broadhead  120 . When the pin  126  is in the open state of  FIG. 3C , the vibrator  160  is OFF, and when the pin  126  is in the closed state of  FIG. 3D , the vibrator  160  turns ON. The pin  126  may be held in place by small O-rings, snap-rings or other mechanical means. 
       FIGS. 3E and 3F  show an embodiment of a broadhead  180  of the mechanical type that includes two physical positions, a closed position illustrated in  FIG. 3E , and an open position illustrated in  3 F. While in the closed position of  FIG. 3E , blades  184  are held close to the longitudinal axis of the broadhead  180  and a tip  182  is in an extended position. Then, when the arrow strikes its target, the tip  182  of the broadhead  180  moves to the closed position as illustrated in  FIG. 3F . Moving the tip  182  to the closed position activates the blades  184  to extend away from the longitudinal axis, and expanding the size of the wound channel created by the broadhead  180 . In addition, the tip  182 , or other switching mechanism as described herein, controls the operation of the vibrator  160  that vibrates the broadhead  180 . In this way, the arrow to which the broadhead  180  is attached can travel to its target having its blades  184  in the closed position and the vibrator OFF, then, after striking the target, the blades move to the open position and the vibrator is turned ON. In some embodiments the tip  182  controls operation of both functions, while in other embodiments each function, i.e., extending the blades  184  and operating the vibrator  160  may be controlled by separate switches, and therefore operated independently from one another. As described above, the tip  182  need not be in the shape as illustrated, and may take nearly any form that allows its function. 
     Although the above embodiments describe a switching mechanism that controls operation of the vibrator  60 ,  160 , it is possible that the vibrator  60  or  160  be manually controlled by the hunter before launching the arrow. In other words, in some embodiments the hunter may turn ON the vibrator  160  before launching the arrow or upon arrow launch with the use of a nock switch. The arrow may travel less efficiently through the air on its way to the target, but such performance may be acceptable to eliminate the operation of the switch that turns ON or OFF when the arrow strikes the target. Such an embodiment may be preferable when the cost of including the switch is prohibitive, or to eliminate the possibility of the switch not operating properly. 
       FIG. 4  is a side view of an arrow shaft  200  having a threaded insert  230  that includes a vibrating mechanism according to embodiments of the invention. The threaded insert  230  includes a threaded receiver  232  for receiving a standard broadhead (not shown) or even a field point for an arrow or other head. A vibrator  260  includes a vibratory motor  240  powered by a battery  290 . A switch  280  may be mechanical or based on an accelerometer as described below. A housing  250 , such as plastic, nylon, or aluminum, may be used to receive and hold all of the components of the vibrator  260 . 
     The vibratory motor  240  is coupled to a spinning head  244  that is either eccentrically mounted or not completely circular. The spinning head  244  may be shaped as an approximate one-half cylinder as is known. In one embodiment the motor has a body diameter of approximately 6 mm and a length of approximately 10.3 mm. When spinning, the vibratory system generates approximately 2.4 G at 11,500 rpm, for example. 
     The switch  280  may be a mechanical switch as described above, or may instead be an electrical switch. Some embodiments could use an accelerometer-controlled G switch, which may be able to detect acceleration in one or more than one direction. For example, the switch may be able to detect when the projectile was launched, during acceleration, or may be able to detect when the projectile hits a target, during deceleration. Other switches may be able to detect both acceleration and deceleration. Embodiments could use specifically designed accelerometer switches mounted to a circuit board, for example, to control the switching function. 
     An advanced switch  280  may include a dual-direction g-sensor that is structured to turn on when the arrow strikes a target and structured to turn off when the arrow is struck on its nock. In such an embodiment the vibrator  260  may be initially in an OFF state, then turn ON when the arrow strikes the target and the switch detects a change in the g-force. After the arrow is retrieved, the hunter could turn off the vibrator  260  by tapping the arrow on its nock, in other words, in the reverse direction that caused the switch to turn on. 
     The switch  280  may also be embodied by other types of switches, such as an impact switch, crush switch, or electrical switches, such as an electrical resistance detector coupled to the broadhead or shaft. In the latter example the electrical resistance would change when the arrow strikes the animal, which, in turn could be used to signal the start of the vibrator. Similarly the switch  280  could be a capacitive detector triggered by sensing a change in capacitance. 
     The battery  290  may be a 1.5 volt or 3 volt lithium battery, or other battery, sized to fit within the shaft of the arrow, or other power supply appropriately shaped and sized for the implementation. The battery  290  may be of the rechargeable type and structured to recharge through a plug (not shown), or structured to be charged by connecting electrodes (not shown) near the edge of the threaded insert  230  to a power source. 
     The entirety of the vibrator  260 , including the motor  240 , switch  280 , and battery  290  may be self-contained within the shaft  200 , which may be made of aluminum or carbon, for example. The vibrator  260  may first be placed into the encapsulating housing  250 , such as formed of plastic or aluminum, before being inserted into the shaft  200 . 
       FIGS. 5A ,  5 B,  5 C, and  5 D are side views of example blades of a broadhead shaped to maximize vibrational energy according to embodiments of the invention. As described above, the broadhead typically includes two, three, or four blades, although embodiments of the invention work with any number of blades in the broadhead. 
     A blade  302  in  FIG. 5A  includes solid portions  302 ,  304  as well as a void  303 . As described above, blades, such as blade  302  may be made by any means, although it may be convenient to make blades by metal injection molding. After being removed from the mold, one or more edges of the blade are sharpened, in some cases as sharp as a razor. Solid portion  304  of blade  302  is designed to maximize vibrational oscillation as solid portion  304  is a suspended feature. In other words, the long vertical edge as illustrated in  FIG. 5A  is held fast in the broadhead to which it is attached to. Then, as the broadhead vibrates, the solid portion  304  vibrates even more than the main body of the broadhead, as the sold portion  304  is only connected to the blade  302  through a small sliver of material between the solid portion  304  and main blade portion  302 . 
     As illustrated in  FIG. 5B , a blade  312  includes sold portions  314  as well as voids  313 . Blade  322  of  FIG. 5C  includes a single void  323 , and a blade illustrated in  FIG. 5D  includes three, or any number of, separate sections  332 ,  334 , and  336 , each having their own void  333 ,  335 ,  337 , respectively. 
     Blades illustrated in  FIGS. 5A-5D  may be used in a broadhead to amplify the vibrations generated as described above. For instance, the blade  302  may vibrate, and thus translate more energy into the animal as the arrow to which it is attached pierces and travels through the animal. Different designs and shapes are possible in addition to those illustrated in  FIGS. 5A-5D , which are merely examples to illustrate the concept. Particular blades may be matched to the size and speed of the vibration. 
     In some embodiments the entire arrow system such as described above may be tuned to using particularized parameters such as parameters of the blades, broadhead, shaft size, length, and weight, material, vibration displacement, vibration speed, vibration direction, etc—to maximize vibrational cutting efficiency. 
       FIG. 6  is a side view of an example broadhead including a vibrating mechanism according to embodiments of the invention. A projectile  400  including a vibrator is illustrated. Differently than in the embodiment illustrated in  FIG. 4 , the entire vibrator is included in a broadhead  410 , which is sized and shaped to be inserted into a standard threaded insert  460  for an arrow shaft  470 . In this way hunters may add a vibrator to their existing arrows simply by inserting the broadhead  410 . 
     In more detail, the broadhead  410  includes a vibrator motor  420  attached to a weight  422 . As described above, the weight  422  is off-balance relative to a spinning shaft of the motor  420  and, when the motor  420  spins, the weight  422  imparts a vibrating motion to the broadhead  410  which radiates through the arrow shaft  470  and other parts of the arrow. 
     A coin cell battery  430  is also wholly contained within the broadhead  410  and provides power to operate the motor  420 . Access to the battery  430  is provided by a removable cap  450  that also includes threads  452  to be received by corresponding threads  462  of the threaded insert  460 . A receiver  453  in the cap  450  may be shaped to receive a hex/Allen wrench. Thus, to insert or change a battery, the user inserts a hex wrench in the receiver  453  and spins the cap  450  to separate it from the broadhead  410 . Then the battery  430  may be inserted into the broadhead  410  and the cap replaced. 
     A mechanical switch is provided by a separated point  412  of the broadhead  410 . As described above, the separated point  412  of the broadhead  410  has two positions, an extended position and a closed position. When the separated point  412  is in the extended position, no power is provided to the vibrator motor  420  and no vibration is imparted to the system. When the separated point  412  is in the closed position, such as after the broadhead  410  has struck the targeted animal, a mechanical switch is also closed which completes an electrical path between the battery  430  and the motor  420 , causing the motor to spin and impart vibration to the system. Broadhead  410  may alternatively include a motion switch as described above. In such a case it is likely that the point  412  would be integrated into the broadhead  410 . 
       FIG. 7  is a detailed isometric view of a vibrator motor  520  including a shaft  530  and weight  522 . As illustrated, the weight  522  is offset or asymmetric about the shaft  530 . When powered through a pair of leads  536 , the motor spins the shaft  530 , which in turn spins the offset weight  522 . 
       FIG. 8  is a side view of a broadhead  600  including a vibrational resonance chamber  610  according to embodiments of the invention. The broadhead  600  is sized to fit within a standard threaded insert, and may be used with the vibrational threaded insert illustrated in  FIG. 4  or any other embodiment. The broadhead  600  includes a resonance chamber  610  into which a vibrational weight  612  is formed, placed, or inserted. When the broadhead  600  vibrates, the vibrational weight  612  moves within the resonance chamber  610  until it strikes the side of the resonance chamber. The vibrational weight  612  is preferably metal, but other materials could be used. This interaction of the vibrating broadhead  600  and the weight  612  in the resonance chamber  610  amplifies the vibrating action of the vibrator. Different broadheads  600  may include resonance chambers  610  of various sizes. Similarly, the vibrational weight  612  may be larger or smaller depending on application and design. By including these variations different broadheads  600  may be selected depending on the particular mechanics of the vibrator system, and depending on how much vibration the hunter wishes to generate for the particular purpose. 
     Although described above as the vibrator being wholly contained in the arrow shaft, or wholly contained within the broadhead, a hybrid option is possible that includes various components in various locations. Thus, the energy source could be contained in the nock, shaft, threaded insert, broadhead, or separately attached to the arrow system. The energy source may be shared with other energy-consuming devices in the arrow system, such as lights or audio devices sometimes used to provide tracking of arrow flight path and a retrieving signal to the archer. 
     The vibration mechanism such as the vibrator motor and asymmetric weight could likewise be placed in the nock, shaft, threaded insert, broadhead, or separately attached to the arrow system. Finally, as described above, the switch to initiate the vibration could be located in the nock, shaft, threaded insert, broadhead, or separately attached to the arrow system. The switch may also be located between various components. For example a switch could be integrated into where the nock inserts into the shaft, into where the threaded insert inserts into the shaft, into where the broadhead inserts into the threaded insert, or at the base, midline, or tip of the broadhead. In such embodiments the switch may include a small or weak spring to keep the sections physically separated but that readily collapses when the arrow strikes a target. When the spring deforms, the switch turns on. A stay-on circuit, such as one including a silicon-controlled rectifier, or similar device could be used to keep the vibrator operating even after the spring had returned to its resting position after having struck the target. 
     In all of the embodiments an additional lighting circuit could be easily integrated into the vibrating circuitry to illuminate when the vibrator was vibrating. For example an LED could be mounted with the nock, arrow shaft, threaded insert, or broadhead to illuminate when the vibrator was vibrating. The LED could be powered by the same power source as the vibrator motor, and could be switched on using the same switch that controls the vibrator. 
     Having described and illustrated the principles of the invention with reference to illustrated embodiments, it will be recognized that the illustrated embodiments may be modified in arrangement and detail without departing from such principles, and may be combined in any desired manner. And although the foregoing discussion has focused on particular embodiments, other configurations are contemplated. 
     In particular, even though expressions such as “according to an embodiment of the invention” or the like are used herein, these phrases are meant to generally reference embodiment possibilities, and are not intended to limit the invention to particular embodiment configurations. As used herein, these terms may reference the same or different embodiments that are combinable into other embodiments. 
     Consequently, in view of the wide variety of permutations to the embodiments described herein, this detailed description and accompanying material is intended to be illustrative only, and should not be taken as limiting the scope of the invention. What is claimed as the invention, therefore, is all such modifications as may come within the scope and spirit of the following claims and equivalents thereto.