Abstract:
A mechanical bird removal device, wherein a bow string is pulled taut, by means of a tow line, across an area to be swept free of unwanted birds. Upon activation of the device, the tow line is allowed to momentarily “free wheel”, thus releasing the bow string to sweep across the area, thus scaring or physically forcing the birds away. Once the area has been swept free of birds, the tow line once again is reeled in and thus resets the bow string for the next cycle.

Description:
This application claims priority from U.S. Provisional Patent Application No. 60/135978 filed May 26, 1999, which is hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a bird removal device, and, more specifically, to a mechanical device that moves and physically forces or frightens birds from a roof, ledge, or other object on which they are perched. 
     In urban environments, bird “infestations” can present a variety of problems. For example, near airports, birds are a hazard to arriving and departing planes. Birds and bird droppings can also present substantial health hazards to the community at large. For example, birds carry many diseases that can be transmitted to humans. 
     Thus, a wide variety of bird removal systems has been developed for dealing with unwanted birds. Many such devices use sirens, alarms, or similar sound devices to frighten the birds. However, birds may become accustomed to such devices and thus are no longer frightened away. Another alternative is to introduce chemical substances into the birds&#39; food supply, but these chemicals may also adversely affect other wildlife. 
     SUMMARY OF THE INVENTION 
     It is therefore the object of the present invention to provide a simple device that removes unwanted birds from a roof, ledge, tree, or similar area. 
     It is a further object of the present invention to provide a bird removal device that will consistently serve its purpose regardless of the birds&#39; familiarity with the device. 
     It is still a further object of the present invention to provide a bird removal device that is non-lethal and will not adversely affect other wildlife. 
     These and other objects and advantages of the present invention will become apparent upon review of the following description. 
     The present invention produces physical movement which literally forces the birds to move or frightens them to do so. Normally, both effects are produced simultaneously. 
     In a preferred embodiment, a long bow string is stretched, so it is taut between two anchor points, using an elastic cord or some other mechanism such as a spring, a weight on a pulley, or even a fiberglass rod. A tow line is attached to the bow string, and this tow line pulls back on the bow string, moving the bow string to a cocked position. One end of the tow line is secured to the bow string, and the other end is attached to a wind-up spool which is part of a retractor mechanism. 
     Upon activation, the wind-up spool is allowed to unwind freely, which allows the bow string to snap back, sweeping the area of birds and preferably making a loud noise. After releasing the bow string, the device begins reeling the tow line back up, making a clicking noise, slowly sweeping the area again, and re-cocking the bow string. Thus, the bow string swings swiftly across the area to be kept free of birds, physically forcing the birds off their perch regardless of how comfortable or familiar they may have become with the device. In order to accomplish this, the bow string should sweep across the area at a height which is low enough to make contact with the birds perching in the area. Typically, the bow string would sweep a path which is substantially parallel to and within one foot of the perching surface. Furthermore, the bow string sweeps back again over the surface as it is brought back to the cocked position, and, while doing so, the retractor mechanism is emitting an audible clicking sound which further serves to scare the birds away. 
     There may be several configurations to accomplish the desired effect of physically removing unwanted birds. In one such configuration, tree limbs are shaken to both remove the birds and scare them away. In this case, one or more tree limbs are pulled back by the tow line (instead of pulling back on a bow string). When the mechanism is triggered, the tow string unwinds freely from the take-up spool, allowing the tree limb(s) to snap back. Other configurations may involve moving frightening objects such as tinsel cord or a cord with streamers, moving noise making objects, or multiple bow string lines and pulleys in order to sweep multiple areas. 
     The activation of the device of the present invention may be accomplished in any of a number of ways. It can be activated manually, by a timer, a motion sensor, a heat sensor, or even a sound sensor such as that described in U.S. Pat. No. 4,965,552, which is hereby incorporated by reference. The sound sensor “listens” for environmental sounds in the vicinity of the device. It compares the sounds it hears against a database, and, when it detects the same sound as that of the unwanted bird species, it generates a signal which may be used to activate the device of the present invention. 
     While the embodiment of the invention shown herein is a simple bird removal device, it will be clear to those skilled in the art that it can also be used with various other configurations having various bow strings, pulleys, and adjustments so as to deter birds in any given area. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic plan view of an installation of a bird removal device made in accordance with the present invention; 
     FIG. 2 is a view, taken along the line  2 — 2  of FIG. 1, showing the mechanical retractor used to pull in the tow rope (with its cover removed); 
     FIG. 3 is a front end view of the mechanical retractor of FIG. 2 (taken from the left side of FIG. 2, again with the cover removed); 
     FIG. 4 is the same view as that of FIG. 3, except that the retractor is in the position which allows “free wheeling” of the wind-up spool; 
     FIG. 5 is a view taken along line  5 — 5  of FIG. 3; 
     FIG. 6 is a schematic plan view of a second embodiment of a bird removal device made in accordance with the present invention; 
     FIG. 7 is a schematic plan view of a third embodiment of a bird removal device made in accordance with the present invention; 
     FIG. 8 is a schematic plan view of a fourth embodiment of a bird removal device made in accordance with the present invention; 
     FIG. 9 is a schematic plan view of a fifth embodiment of a bird removal device made in accordance with the present invention; 
     FIG. 10 is a schematic plan view of a sixth embodiment of a bird removal device made in accordance with the present invention, showing multiple sweep lines; 
     FIG. 11 is a schematic plan view of a seventh embodiment of a bird removal device made in accordance with the present invention, showing multiple sweep lines; 
     FIG. 12 is a schematic plan view of an eighth embodiment of a bird removal device made in accordance with the present invention, showing the shaking of tree limbs; and 
     FIG. 13 is a schematic plan view of a ninth embodiment, in which the tow cord is retracted by a non-powered retractor, and the bow string  12  is retracted by a powered retractor. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1-5 show a first preferred embodiment of a bird removal device  10 . In FIG. 1 it can be seen that the device  10  includes a bow string  12 , shown in the at-rest position by a solid line and in the “cocked” position by the dashed line. A tow line  14  is secured at one end to the bow string  12  at the point P 5 , and at the other end to a powered retractor mechanism  30 , which will be described in more detail later. 
     A first end of the bow string  12  is securely fastened to an anchor P 1  which is secured to the ground. The bow string  12  is strung around a second anchor P 2  which, in this instance, is a pulley. The second end of the bow string  12  is then secured to a spring  16 , which, in this embodiment, extends around a pulley P 6  and is anchored to the ground at the point P 7 . The spring  16  may be a simple coil spring, a bungee cord, or even a flexible rod such as a fiberglass rod, and serves as a non-powered retractor. For some spring arrangements, the pulley P 6  would be omitted. The spring  16  stretches to allow the bow string  12  to travel from its “at rest” position (shown in solid line) to its “cocked” position (shown in broken line), and then the spring force swiftly returns the bow string  12  to its “at rest” position when the tow line is released, and, in so doing, causes the bow string  12  to sweep across the perching surface  11  where the birds perch. 
     The tow line  14  is secured at its first end P 5  to the bow string  12 . The tow line  14  then extends around a anchor point P 3  (which in this instance is a pulley), and may work its way around other pulleys P 4  before its second end is secured to the retractor mechanism  30 , which is itself also secured to the ground. 
     Once the retractor mechanism  30  is engaged, the second end of the tow line  14  is wound up onto a wind-up spool (this mechanism is described later), and thus the first end of the tow line  14  is pulled toward the anchor point P 3 . Since the bow string  12  is attached to the tow line at point P 5 , as the first end of the tow line is pulled toward anchor point P 3 , so is the point P 5  on the bow string  12  also pulled toward the anchor point P 3 . 
     When the point P 5  reaches the point P 3 , the bow string  12  is stretched in the cocked position shown in broken line. At this point, a mechanical stop (described later) prevents the tow line  14  from winding up any further, and the retractor stops pulling on the tow line  14 . The bow string  12  is now cocked. When the tow line  14  is released (described later), the bow string  12  is free to return to its “at rest” position, and it is urged to do so very quickly by the tension exerted by the spring  16  on the bow string  12 . As the bow string  12  snaps back to its “at rest” position shown in solid line, it sweeps an area defined by the points P 1 , P 2 , and P 3 , thus physically removing any birds which may be perched within the area  11  being swept by the bow string  12 . 
     Once the bow string  12  has snapped back to its “at rest” position, the retractor mechanism  30  starts retracting the tow line  14  once again, so as to bring the bow string  12  back in the cocked position (shown in broken line). As it does so, the bow string  12  once again sweeps the area  11  defined by the points P 1 , P 2 , and P 3 , and, while it does so, the retractor mechanism  30  emits a clicking sound which also further contributes to scare any birds away. Thus, not only are birds physically dislodged by the bow string  12  as it snaps to its “at rest” position; the return sweep will also dislodge any birds which may have flown right back to their perch  11 , and the commotion of all the birds being physically dislodged, together with the clicking sound emitted by the retractor mechanism  30 , will serve to remove unwanted birds, not only in the area  11  which was swept by the bow string  12 , but also in the vicinity of this same area  11 . 
     FIGS. 2 and 3 show a side view and a front end view, respectively, of the retractor mechanism  30  of the present invention, which is intended to be enclosed in a box (not shown). The retractor  30  includes a small electric motor  32  with an output shaft  34 . A circuit board  55  serves as the controller to control the motor  32 . Mounted coaxially on this output shaft  34  are a ratchet wheel  36 , and a first friction wheel  38  which is parallel to and directly behind the ratchet wheel  36  as seen in FIG.  3 . The ratchet wheel  36 , the friction wheel  38 , and the output shaft  34  of the motor  32  all rotate as a single unit about the axis  34 A, and this entire assembly is mounted as a single item onto a platform or base  40 . 
     A second friction wheel  42  (which is identical to the first friction wheel  38 ) and a wind-up spool  44  are mounted on a common shaft  46 , and they also rotate as a single unit about an axis  46 A. This second friction wheel assembly is mounted as a single item onto a subframe  48 , which in turn is fixed to the base  40  and is placed so that the output shaft  34  of the motor  32 , and the shaft  46  of the second friction wheel assembly are both parallel and in spaced apart relationship to each other, and the first and second friction wheels  38  and  42  respectively are radially aligned with each other, as shown in FIG.  5 . Thus, the first and second friction wheel assemblies  38 ,  42  rotate about parallel axes of rotation  34 A,  46 A, which are fixed relative to the base  40 . 
     The subframe  48  is a U-shaped wall (as seen in FIG. 5) and has a fixed arm  49  projecting horizontally outwardly (as seen in FIGS.  3 - 5 ), the purpose of which will be explained later. The tow line  14  is attached at one end to the wind-up spool  44  such that, when the wind-up spool turns clockwise (as shown by the arrow in FIG. 3) the tow line  14  passes over a support roll  45  and is wound onto the wind-up spool  44 . Naturally, as the wind-up spool  44  turns counterclockwise, the tow line  14  unwinds from the wind-up spool  44 . 
     A third friction wheel  50  is rotatably mounted, via an axle  52 , to a pivoting frame  54 , so as to rotate about an axis  52 A. The pivoting frame  54  is pivotally mounted to the subframe  48  via a pivot axle  56 , which is directly above the second friction wheel axle  46 , such that the pivoting frame  54  is free to pivot about a pivot axis  56 A relative to the fixed base  40 . The pivot frame  54  may pivot clockwise as seen from the vantage point of FIG. 3 until the pivot frame  54  hits the outwardly projecting arm  49  of the subframe  48 , which then acts as a stop to prevent further rotation of the pivot frame  54 . 
     The axle  52  of the third friction wheel  50  is located above and parallel to the shafts  34  and  46  of the first and second friction wheels  38 ,  42 , and all three friction wheels  38 ,  42 ,  50  are radially aligned, as shown in FIG. 5, with the third friction wheel  50  located above and between the first and second friction wheels  38 ,  42 . When the pivot frame  54  pivots counterclockwise (as seen from the vantage point of FIG.  3 ), the tread surface of the third friction wheel  50  comes to rest upon, and is in frictional contact with, the tread surfaces of both the first and second friction wheels  38 ,  42 , as shown in FIG.  3 . The tread surfaces of the friction wheels  38 ,  42 ,  50  preferably are all made from a 60A Shore hardness urethane material called K•Prene, Grade K-66A, available from Acrotech, 980 West Lakewood Ave. Box 466, Lake City, Minn. 55041. This material is the correct hardness to provide good frictional contact between the friction wheels  38 ,  42 ,  50 . 
     A downwardly projecting ratchet lever arm  58  and a spring  60  are both mounted to the pivot frame  54  on the same side as the third friction wheel  50 , relative to the pivot axis  56 A. The spring  60  extends from the pivot frame  54  to the base  40  and provides a force which pushes the tread surface of the third friction wheel  50  against the tread surfaces of the first and second friction wheels  38 ,  42 . The ratchet lever arm  58  extends downwardly from the pivot frame  54  and comes to rest against the teeth  62  of the ratchet wheel  36  such that, as the ratchet wheel  36  turns clockwise, the lever arm  58  clicks against the ratchet teeth  62 . However, when the ratchet wheel  36  turns counterclockwise, the lever arm  58  locks into one of the ratchet teeth  62 , and the ratchet wheel  36  pushes the lever arm  58  up, forcing the pivot frame  54  to pivot clockwise until the pivot frame  54  hits the outwardly projecting arm  49  of the subframe  48 . At this point, as shown in FIG. 4, the third friction wheel is lifted up out of contact with the first and second friction wheels  38 ,  42 , and the ratchet wheel  36  is prevented from further rotation in the counterclockwise direction. A small gap G 1  is formed between the first friction wheel  38  and the third friction wheel  50 , and a small gap G 2  is formed between the second friction wheel  42  and the third friction wheel  50 . 
     When the third friction wheel  50  (which we now refer to as the idler wheel  50 ) is raised so that there is no frictional contact between the three friction wheels  38 ,  42 ,  50 , then the idler wheel  50  and the second friction wheel  42  are able to freewheel. The tow line  14 , which is wound around the wind-up spool  44 , is now free to unwind as the wind-up spool freewheels with the now freewheeling second friction wheel  42 . The tow line  14  is secured to the bow string  12  at point P 5 , and the bow string wants to snap back to its “at rest” position thanks to the force exerted by the spring  16 . With the resistance from the friction wheels  38 ,  42 ,  50  now removed, the bow string snaps back to its “at rest” position, pulling the tow line  14  with it and unwinding the tow line  14  from the wind-up spool  44 . 
     Referring now also to FIG. 4, upon receipt of a signal from the controller, the motor  32  begins counterclockwise rotation, engaging the lever arm  58  with the ratchet teeth  62  such that the lever arm  58  is raised and the pivot frame  54  pivots clockwise until the pivot frame  54  is stopped by the arm  49  projecting from the subframe  48 . The pivoting action of the pivot frame  54  is enough to lift the third friction wheel  50  away from its normal frictional contact with the other two friction wheels  38 ,  42  as described earlier. The controller may be triggered manually by an operator, by a timer, a motion sensor, a heat sensor, or even a sound sensor, or by other known methods. 
     After a short period of time (2.5 seconds in the present embodiment), the controller signals the motor  32  to stop counterclockwise rotation and to begin rotation in a clockwise direction. The lever arm  58  is now disengaged, and the spring  60  rotates the pivot frame  54  counterclockwise, and with it moves the idler wheel  50  downwardly so that the gaps G 1  and G 2  are eliminated and all three friction wheels  38 ,  42 ,  50  are once again in frictional contact at their respective tread surfaces. As the motor  32  turns clockwise, it turns the first friction wheel in the same direction, which turns the idler wheel  50  counterclockwise, which turns the second friction wheel  42  in a clockwise direction, thus also turning the wind-up spool  44  and causing the tow line  14  to wind up onto the spool  44 . As the tow line  14  is wound onto the wind-up spool  44 , it is retracting the other end of the tow line  14 , and with it the bow string  12  until it is back in the cocked position (shown in broken line). At this point, a detent  18  (which in this case is an enlargement such as a ring or a knot secured to the tow line  14  and which is too large to fit through the opening  64  where the tow line  14  enters the retractor mechanism  30 ) stops the tow line  14  from winding any further onto the wind-up spool  44 , and the retractor mechanism  30  stalls and stops, leaving the bow string cocked and ready to repeat the cycle upon receipt of a new signal from the controller. 
     Thus, the bow string  12  normally sits in the cocked position (shown in broken line in FIG. 1) ready to snap back to its “at rest” position (shown in solid line), urged there by the spring  16 . When a signal is received at the motor  32 , the initial counterclockwise rotation allows the wind-up spool  44  to freewheel, effectively releasing the tow line  14  and thus allowing the bow string  12  to snap back to its “at rest” position, and in the process sweeping the area  11  so as to physically remove any birds perched therein. After a short period of time, the controller signals the motor  32  to reverse direction and the motor  32  rotates clockwise. The lever arm  58  clicks as each ratchet tooth  62  passes under the lever arm  58 , and the spring  60  pulls the friction wheels together so that the wind-up spool  44  is once again reeling in the tow line  14 . As the tow line  14  is retracted, it pulls the bow string  12  back over the area  11  to be protected from perching birds, accompanied this time by the clicking sound of the lever arm. 
     FIG. 6 is a schematic view of a second embodiment of the present invention. This arrangement  10 A is very similar to the arrangement of the first embodiment  10  shown in FIG. 1, except that the bow string  12  is urged back to its “at rest” position by a flexible rod  16 A (such as a fiberglass rod) instead of by the spring  16  of FIG.  1 . 
     FIG. 7 is a schematic view of a third embodiment of the present invention. This arrangement  10 B is very similar to the first embodiment shown in FIG. 1, except that the bow string  12  is urged back to its “at rest” position by a weight  16 B acting over a pulley P 2  instead of by the spring  16  of FIG.  1 . 
     FIG. 8 is a schematic view of a fourth embodiment  10 C of the present invention. This is similar to the first embodiment shown in FIG. 1 except that in this embodiment the tow line  14  is directly in line with the bow string  12  (and in fact may be the end portion of the bow string itself), and the sweeping action of the bow string  12  is in line with the motion of the tow line  14  instead of being generally perpendicular to the motion of the tow line  14  as in the previous embodiments. To accomplish this, the tow line  14  is attached to and end of the bow string  12 , instead of to a point in between the two end points of the bow string  12 . In this fourth embodiment, the bow string  12  includes a tinsel cord, used to cause additional motion and noise among the birds. As discussed earlier, tinsel cord may be used interchangeably with the bow string  12  in many of the embodiments of the present invention. 
     FIG. 9 is a schematic view of a fifth embodiment  10 D of the present invention. This is very similar to the third embodiment  10 B shown in FIG. 7, except that the bow string  12  is connected to the tow line  14  at two different points via the rings  20 . When the tow line  14  is fully retracted so that the rings  20  are up against the pulleys P 3  and P 4 , then the area to be swept by the bow string  12 , when it is released, is a quadrangle defined by the points P 1 , P 2 , P 3 , and P 4 , instead of the triangular shaped areas swept by the first, second, and third embodiments. In fact, many differently-shaped areas may be swept by the release of the bow string  12 , depending on the location and number of tow lines  14  and pulleys  20  used. 
     FIG. 10 is a schematic view of a sixth embodiment  10 E of the present invention. This is very similar to the first embodiment shown in FIG. 1, in that a spring  16  is attached to one end of the bow string  12 . The most important difference between this sixth embodiment and the first embodiment is that there are multiple bow strings  12  secured to multiple anchor points P 1  and P 2 , and these multiple bow strings  12  are secured to a common tow line  14 . As the tow line  14  is retracted by the retractor mechanism  30 , the tow line  14  will pull and cock the multiple bow lines  12 . When the tow line  14  is released, the multiple bow strings  12  simultaneously sweep multiple bird perching areas. 
     FIG. 11 is a schematic view of a seventh embodiment  10 F of the present invention. This is very similar to the sixth embodiment shown in FIG. 10 in that there are multiple bow strings simultaneously sweeping multiple bird perching areas, except that there are now multiple tow lines  14 , each connected to its own bow string  12 , and the multiple tow lines  14  come together at one point  18 , where they join together before going to the retractor mechanism  30 . As in the case of the sixth embodiment, as the tow line  14  is retracted by the retractor mechanism  30 , the tow line  14  will pull and cock the multiple bow lines  12 . When the tow line  14  is released, the multiple bow strings  12  simultaneously sweep multiple bird perching areas. 
     FIG. 12 is a schematic view of an eighth embodiment  10 G of the present invention. In this instance there is no bow string. Instead, the tow line  14  is attached to a branch  66  of a tree  68 . The branch  66  is shown in solid line as it is being pulled back into the cocked position by the tow line  14  which is connected to the retractor mechanism  30 . The branch  66  itself serves the function of the bow string  12  and spring  16  of the first embodiment. When the tow line  14  is released, the branch  66  will swing back to its “at rest” position shown in dotted line, and thus will scare away any birds perched on the branch  66  as well as in any neighboring branches of the tree  68 . Thus, in this instance, the bird removal device is acting, not by sweeping a bow string over a perching surface, but rather by actually moving the perching surface itself. 
     FIG. 13 shows another alternative embodiment  10 G, in which the bow string  12  is secured at one end to a point P 1 , passes over a pulley P 2 , and winds onto the wind-up spool of the powered retractor mechanism  30 . The tow line  14  is secured to the bow string  12  at the point P 5 , to an end point P 3 , and includes a spring  16 . So, in this case, the “at rest” position is when the spring  16  is retracted and the bow string  12  is extended, and the “cocked” position is when the bow string  12  is retracted onto the powered retractor  30  and the spring  16  is extended. 
     It may be noted that, in many of the embodiments, the tow line  14  may be attached to the bow string  12  or tinsel cord by use of a ring which will then allow the tow line  14  to automatically find its best point to pull on the bow string  12 . In some instances this same ring  20  may serve the dual purpose of acting as a detent  18 . 
     It will be obvious to those skilled in the art that modifications may be made to the embodiments described above without departing from the scope of the present invention.