Abstract:
An apparatus is provided for containing an animal in a defined area. The apparatus comprises first and second communicating units; one operatively associated with the animal, and the other positioned to locate the area. At least one of the units is adapted to transmit a signal, and at least one of the units is adapted to receive the signal. A circuit is adapted to measure the transmission time or change in transmission time of the signal and calculate the distance between the first and second units. At least one of the first and second units is configured to emit an output to contain the animal in the area when the transmission time corresponds to the animal leaving the area.

Description:
BACKGROUND OF THE INVENTION 
   It is often desirable to contain an animal within a particular area for one or more reasons, including but not limited to: protection of the animal, protection of people and other animals from the animal, convenience. Various systems have been devised for containing animal. Fences are expensive, require ongoing maintenance, and are permanent. Also, fences may not be appropriate for all terrain and may not be aesthetically pleasing. A buried line that interacts with an animal collar to shock the animal if it crosses the line addresses the aesthetic problem of fences. Such systems, however, are expensive and permanent. A chain anchored at one end and attached to the animal at the other is inexpensive and may be portable by using a stake or the like for an anchor. Chains, however, may easily become tangled in obstructions, and may be inconvenient or dangerous to people walking or playing in the vicinity of the animal. 
   SUMMARY OF THE INVENTION 
   The present invention provides an apparatus for containing an animal in a defined area. The apparatus comprises first and second communicating units. One of the units is operatively associated with the animal and the other unit is positioned to locate the area. At least one of the units is adapted to transmit a signal, and at least one of the units is adapted to receive the signal. At least one of the units comprises a circuit adapted to measure the transmission time of the signal or the change in transmission time of the signal and calculate the distance between the first and second units from the transmission time or change in transmission time. At least one of the first and second units is configured to emit an output to contain the animal in the area when the transmission time or change in transmission time exceeds a set time corresponding to the animal leaving the area. 
   These and other features and objects of the invention will be more fully understood from the following detailed description of the preferred embodiments, which should be read in light of the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and form a part of the specification, illustrate the embodiments of the present invention and, together with the description serve to explain the principles of the invention. 
     In the drawings: 
       FIG. 1  shows an animal contained in an area by an apparatus according to an exemplary embodiment of the present invention; 
       FIG. 2  shows an apparatus according to an exemplary embodiment of the invention having a fixed first unit and a second unit operatively associated with an animal; 
       FIG. 3  shows an apparatus according to an exemplary embodiment of the invention having a mobile first unit and a second unit operatively associated with an animal; 
       FIG. 4  is a block diagram of an apparatus for containing an animal in a defined area according to an exemplary embodiment of the invention; 
       FIG. 5  shows an apparatus according to an exemplary embodiment of the invention having a second unit locating an area and a first unit operatively associated with an animal; 
       FIG. 6  is a block diagram of an apparatus for containing an animal in a defined area according to an alternative exemplary embodiment of the invention; and 
       FIG. 7  is a block diagram of an apparatus for containing an animal in a defined area according to another alternative exemplary embodiment of the invention. 
   

   DETAILED DESCRIPTION 
   In describing the invention illustrated in the drawing, specific terminology will be used for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. 
   With reference to the drawing, in general, and  FIGS. 1–4  in particular, an apparatus and system of the present invention are disclosed for containing an animal within a defined area. 
   A first unit  100  transmits a signal  91  at a predetermined time interval. A second unit  200  receives the signal and measures either the time of transmission or the change in the time of transmission of the signal. In an exemplary embodiment illustrated in  FIG. 1 , first unit  100  is positioned to locate an area  20  in which an animal  10  is to be contained, and second unit is operatively associated with an animal  10 . Area  20  may for example be a circle centered at first unit  100  having a radius  21 , as shown in  FIG. 1 . In the embodiment illustrated in  FIG. 1 , area  20  encompasses a door  22 , which may be a door of a dwelling used for ingress and egress by animal  10 . It will be apparent to those skilled in the art that an area may be defined having a geometry other than a circle, but such geometry would require more than one first unit  100 . 
   As shown in  FIG. 2 , second unit  200  may be operatively associated with animal  10  by incorporating first unit in a collar placed on the animal, attaching first unit to a collar, or implanting first unit below the skin of the animal  10 . First unit  100  may be set in the center of area  20  or fixed in the center of area  20  with a stake or the like. Alternatively, first unit  100  and area  20  may be non-stationary. First unit may, for example, be attached or incorporated into a wristband, hand held device, or the like and worn or held by a person  11 , as shown in  FIG. 3 . 
   As stated previously, second unit  200  measures either the time taken for signal  91  to propagate from first unit  100  to second unit  200  (i.e., transmission time) or the difference in transmission time compared to a reference time. The measured transmission time is compared to a set time corresponding to a distance equal to radius  21  of area  20 . When the measured time of transmission  91  corresponds to a distance equal to radius  21 , second unit  200  propagates an output or warning signal  93  to the animal. Warning signal  93  is adapted to urge animal  10  to return to area  20  to stop the warning signal. Exemplary warning signals include a high frequency sound, audible to the animal, but not to people and a mild electric pulse. 
   As shown in  FIG. 1 , first unit  100  may be positioned such that door  22  is within area  20 . Second unit  200 , operatively associated with animal  10  may be provided with a switch for switching second unit  200  between an active and an inactive state. This switch may be triggered, for example, by an action of a person or a proximity switch mounted at door  22 . When animal  10  is inside the dwelling, second unit  200  may be switched off so that signal  93  is not propagated. 
   In an exemplary embodiment, second unit  200  establishes a baseline or reference time when it is switched on, corresponding to radius  21 . This reference time is used to determine whether second unit  200 , and therefore animal  10  is closer or further from first unit  100  then when second unit  200  was activated. 
   For example, first unit  100  is positioned 45 feet from door  22 . Second unit  200  is activated while animal  10  is 5 feet inside door  22 . Signal  91  is propagated at 50 ms intervals. Second unit receives signal  91  at a time, which is set as the baseline or reference time (i.e., 0). If animal  10  remains stationary, the second propagation of signal  91  will be received 50 ms after the first propagation. If animal  10  has moved closer to first unit  100 , the second propagation of signal  91  will be received less than 50 ms after the first propagation. Similarly if the animal  10  has moved closer to first unit  100 , the third propagation of signal  91  will be received less than 100 ms after the first propagation, and so forth. Conversely, if animal  10  has moved further from first unit  100  the second propagation of signal  91  will be received more than 50 ms after the first propagation, the tenth propagation of signal  91  will be received more than 500 ms after the first propagation, and so forth. When animal  10  moves beyond area  20 , as determined by signal  91  being received a preprogrammed time after its corresponding time (a multiple of the propagation interval) warning signal  93  is generated. The preprogrammed time may be, for example 5 ms, so that when signal  91  is received at 100,006 ms after the first propagation, warning signal  93  is generated. If, for example, 5 ms corresponds to 10 feet, area  20  is a circle having radius  21  of 60 feet. Warning signal  93  continues to be generated until animal  10  returns to area  20 . While second unit  200  is active, animal  10  may move freely within area  20  without becoming tangles by obstacles  25  and without being encumbered by a chain or the like. 
   Referring now to  FIG. 4 , first unit  100  comprises a transmitter  110 , which transmits signal  91 . Transmitter  110  should be understood to be any of a number of components capable of transmitting a signal over operative distances, which can vary from less than 10 feet to over 100 feet, depending upon the area  20  in which animal  10  is to be contained. Transmitter  110  may, for example, be a RF antenna, a broadband transceiver, a microwave transceiver, or any other component capable of transmitting a short, identifiable signal. A signal  93 A is generated by a circuit  120  at regular intervals established by clock  130 , and sent to transmitter  110 . Signal  93  is then propagated from transmitter  110 . 
   In an alternative exemplary embodiment, as shown in  FIGS. 5 and 6 , first unit  100  is operatively associated with animal  10 , and second unit  200  is positioned to locate an area  20 . As in the exemplary embodiment described above, a transmitter  110  in first unit  100  transmits a signal  91 , and a receiver  210  in second unit  200  receives signal  91 . A logic circuit  220  in second unit  200  measures the time of transmission or the change in the time of transmission of signal  91  from first unit  100  to second unit  200 , using a clock  230 . When animal  10  leaves area  20 , second unit  200  transmits a warning signal  93 . Warning signal  93  may, for example, be a sound wave at a frequency audible to animal  10 . Warning signal  93  may be transmitted from a transmitter  240 . If signal  91  and warning signal  93  are compatible, receiver  210  and transmitter  240  may, in fact, be a single transceiver. 
   A logic circuit  120  in first unit  100  provides a signal  91 A to transmitter  110  at a preprogrammed interval using clock  130 . This causes transmitter  11  to propagate signal  91  at the programmed interval. Logic circuit  120  may be activated and deactivated using a switch  160 . 
   First unit  100  may include a receiver  111 , which receives warning signal  93  and transmits a signal  93 B to control circuit  120 . If warning signal  83  continues for a set period of time, logic circuit activates an output device  150 , which generates an output  95  causing animal to return to area  320 . Output device  150  may, for example, be an electrode that generates a mild shock. 
   In an exemplary embodiment, clocks  130  and  230  are synchronized. Logic circuit  120  causes transmitter  110  to generate signal  91  at a pre-determined interval, for example each tenth of a second. The time of transmission for signal  91  is measured by dividing the difference between the time at which signal  91  is received and the time it was transmitted (i.e., 0.010 seconds, 0.020 seconds, 0.030 seconds . . . ) by the rate of propagation or for the particular form of signal. 
   Referring now to  FIG. 7 , in another alternative exemplary embodiment, first unit  100  is operatively associated with animal  10 , and second unit  200  is positioned to locate an area  20 . As in the exemplary embodiment described above, a transceiver  110 T in first unit  100  transmits a signal  91 , and a repeater  210 R in second unit  200  receives signal  91  and repeats it as signal  92 . Transceiver  110 T receives signal  92  and forwards it to a logic circuit  120  in first unit  100 . Logic circuit  120  measures the time of transmission of signals  91  and  92 , using a clock  230 . When animal  10  leaves area  20 , as determined by a time of transmission corresponding to radius  21  of area  20 , an output device  150  of first unit  100  transmits a warning output  95 . Warning output  95  may, for example, be an electric pulse. Repeater  210 R may also forward signal  91  to an optional logic circuit  220  in second unit  200 . Logic circuit  220  may measure the time of transmission for signal  91 . Then, when the time of transmission of signal  91  corresponds to a distance slightly less than radius  21  of area  20 , logic circuit transmits a signal to output device  240 , causing it to transmit a warning signal  93 . Warning signal  93  may be, for example, a sound wave audible to animal  10 . In  FIG. 7 , second unit  200  is equipped with a switch  260  to activate and deactivate the system. It should be understood, however, that first unit  100  may be equipped with a switch instead of or in addition to second unit  200 . 
   Although this invention has been illustrated by reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made which clearly fall within the scope of the invention. The invention is intended to be protected broadly within the spirit and scope of the appended claims.