Abstract:
A retractable dog leash system is designed to attach to the collar of a pet and be permanently worn in this manner is small and lightweight, and comprises an ergonomic handle that fits neatly against the case when the leash is in a retracted condition. Advantageously, the leash system comprises a leash retraction biasing mechanism that is free on one end permitting an unwinding of the biasing mechanism and not merely a tightening of it.

Description:
BACKGROUND OF THE INVENTION 
     The invention is directed to a pet leash system that is designed to be worn on the collar of a pet. 
     Such systems are known from, e.g., U.S. Pat. No. 4,328,766 which discloses a retractable leash that is barrel shaped and has leaf spring that is coaxial with a spool upon which the leash is wound, as well as a ring to which an additional leash or handle may be affixed. 
     U.S. Pat. No. 4,018,189 shows a similar design that has a bar-style handle attached to the leash. This is also disclosed by U.S. Pat. No. 4,197,817 where the bar-style handle is segmented into three sections that may be straightened when the collar is in use. Related designs can be found in U.S. Pat. Nos. 4,964,370 and 4,977,860. 
     All of these systems utilize either no affixed handle or else have an affixed handle that is not ergonomic or does not mate cleanly with the case in a small and lightweight manner. Furthermore, all of these systems use a bias spring that is rigidly fixed at its center point end that only permit a tightening of the spring of the spring when the leash is extended. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an attachable leash to an animal collar that is small, lightweight, and has a low profile so that it may be worn by the animal without discomfort due to weight and bulkiness, and that has an ergonomic handle. 
     The object of the invention is achieved by an extendable pet leash system configured to be worn on a pet collar, comprising: a case; an attachment mechanism that is affixed to the case and is configured to attach the leash system to a pet collar; a grip handle configured to mount on an exterior portion of the case; a leash attached to the grip handle; a leash spool having the leash coiled about it in a retracted state and comprising a spool spindle about which it rotates; a thin coil negator spring that is not fixed on one end and is free to rotate, and affixed on an other end to the leash spool, the negator spring configured to provide a rotational bias to the leash spool in a leash retraction direction; a stop mechanism configured to permit the leash to be extended, but preventing the leash from retracting based on the bias of the negator spring; and a stop release mechanism configured to disengage the stop mechanism and permit the lease to be retracted. 
     This object is also achieved by an extendable pet leash system configured to be worn on a pet collar, comprising: a case; an attachment mechanism that is affixed to the case and is configured to attach the leash system to a pet collar; a grip handle configured to mount on an exterior portion of the case having an outer portion that roughly approximates a case curvature, and an inner portion that has at least one grip curve configured to mate with a matching curve of the case thereby creating a gapless mating surface between the inner portion of the grip handle and the case when the leash is in a retracted position; a leash attached to the grip handle; a leash spool having the leash coiled about it in a retracted state and comprising a spool spindle about which it rotates; a retracting bias mechanism configured to provide a retracting bias to the leash spool; a stop mechanism configured to permit the leash to be extended, but preventing the leash from retracting based on the bias of the retracting bias mechanism; and a stop release mechanism configured to disengage the stop mechanism and permit the lease to be retracted. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The following drawing figures illustrate various embodiments of the invention that are described below. 
         FIG. 1  is a pictorial isometric view of the pet leash system; 
         FIG. 2  is a pictorial side view showing the clip in an open position; 
         FIG. 3  is a pictorial isometric view showing the leash extended; 
         FIG. 4  is a cross-section top view of the interior of the pet leash system; 
         FIG. 5   a  is a pictorial isometric view of the spring and leash spool; and 
         FIG. 5   b  is a side view of the spring and leash spool. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Various embodiments of the invention are discussed in more detail below.  FIG. 1  illustrates an embodiment of the basic pet leash system  10  with a plastic case  12  that surrounds the internal mechanisms, a clip  14  with clip ring  18  for attaching the leash system  10  to the collar of an animal, and a grip handle  16  that is advantageously configured, when the leash is completely retracted, to mate with and approximately conform to the shape of the case  12 . An outer curve of the grip handle  16  is only slightly more severe than the curve of the case  12 , and the ends of the grip handle  16  are designed to be flush with the case  12  so that no significant gaps are created between the grip handle  16  and case  12  when the leash is retracted. Since the leash system  10  is designed so that it can be worn by the pet at all times, this design feature prevents the leash system  10  from getting caught on various object that a pet is likely to encounter. 
     Although various sizes of the leash are possible, an ideal version of the leash has dimensions of approximately 2″×3″×1.5″, which can permit a leash length of around 44″. 
       FIG. 2  illustrates the mechanism for attaching the leash system  10  to a pet collar (not shown). A clip  14  is attached to the case  12  by way of, e.g., a shaft mounted to the case  12  at a clip pivot point  24 . The clip in this configuration may be biased to close towards the case with a cylindrical spring attached with known methods. Other known biasing mechanisms are possible as well for the clip  14 . It is not necessary to bias the clip  14  towards the case  12 , since a clip ring  18  is provided that can be used with a clip holder  17  to keep the clip  14  in a closed position once it is mounted to the pet collar. Clip grip protrusions  22  may be further utilized to secure the grip on the leash. In a preferred embodiment, the grip protrusions  22  may have a circular cross-section and be pointed on one end to grip the leash and prevent its movement around, although other configurations that inhibit leash movement are considered as encompassed by the invention. 
       FIG. 3  illustrates the leash system  10  with the leash  32  extended. The leash  32  is made of a material that is resilient and difficult to break. It is not abrasive when in contact with a hand or pet, and is very thin. In an embodiment of the invention, the grip handle  16  to which the leash  32  is attached, has curved portions  19  that ideally can be used to hold the leash with two fingers. These curves  19  can also partially define the shape of the case  12  at the mating portion between the grip handle  16  and case  12 . 
     Additionally, it is possible to include a placement and alignment mechanism to keep the grip handle  16  at a particular position with respect to the case  12  when it is retracted.  FIG. 3  illustrates the use of two grip alignment protrusions  30  configured to mate with two grip alignment holes  17  in the grip handle  16 . However, other mechanisms (slots, grooves, indented portions, etc.) could also easily be used to maintain the position of a retracted grip handle  16  to the case. 
       FIG. 4  illustrates the inner workings of the leash system  10 . The leash  32  is wound around a leash spool  56  that is affixed to the case  12  via a spool spindle  59  around which the spool  56  can rotate. A thin coil negator spring  42  designed as a clock spring has an inner end that is not rigidly affixed and is free to rotate around as the spring  42  is unwound while extending the leash  32 . The negator spring  42  may simply utilize the case  12  and internal mechanisms to bound the negator spring on its outer periphery and possibly guides to assist positioning the spring. Alternately, some mechanism may be provided within a central portion of the negator spring  42  to keep the spring in position, provided the inner end of the spring  42  is not affixed to this mechanism and permits the spring  42  to rotate freely. 
     In an advantageous embodiment, this spring  42  can be almost entirely unwound when the leash  32  is fully extended (e.g., with only 1.5 turns remaining)—advantageously, this free end that allows the spring to be unwound provides a significantly greater degree of leash  32  extension than systems in which the biasing spring is rigidly fixed/mounted at its center and simply tightens in response to a leash extension. This permits a much longer leash to be used while at the same time helping to minimize the size of the case. 
     The spring  42  has a recoil memory that is configured to provide a bias on the leash spool  56  in a retracting or winding direction. In order to prevent a constant pulling force on the extended leash  32 , a stopping mechanism may be provided. One possible embodiment of such a stopping mechanism can be seen in  FIG. 4  comprising a pointed stop  44  mounted on a stop pivot  46 . The pointed portion of the stop  44  is angled such that the point digs into the material on some portion of the leash spool  56  when the spool is being turned in a direction to retract the leash  32 , thereby preventing further rotational motion of the spool  56 , but so that the point simply drags along on the leash spool  56  when it is rotating in a direction to extend the leash  32 , thereby permitting motion in this direction. Instead of (or possibly in addition to) the point digging into the material, an appropriately shaped set of teeth (e.g., ramp-step) could be used on the spool  56  to accomplish the same purpose. 
     A force is applied on the stop  44  to drive it into the leash spool  56  by a stop spring  48  affixed to an end of the stop  44  having the point. An opposite end of the stop spring  48  is attached to a stop spring biasing mechanism  50  and may possibly utilize stop spring posts that allow a snug it of the stop spring  48  and keep it generally in position. The embodiment shown in  FIG. 4  utilizes a spring in compression on the point end of the stop  44 . However, a spring in tension could just as easily be used on an end opposite the point. 
     The stop  44  may be released permitting retraction of the leash  32  by, e.g., a retractor button  52  that extends outside of the case. When the retractor button  52  is pressed by a user, it causes the stop  44  to rotate about the pivot point  46  via a force at a stop release contact point  54  such that the point disengages from the leash spool  56 . The retractor button may be guided and positioned by use of a guide  45  affixed to the case  12  in conjunction with a parallel hole in the case through which the retractor button  52  extends. A retaining ring  47  may further be provided to prevent the retractor button  52  from traveling too far. 
       FIGS. 5A and 5B  show in more detail the association of the thin coil negator spring  42  with the leash spool  56 . The leash spool has two portions: the leash portion  56   a  around which the leash  32  is wound, and the spring portion  56   b  around which a take-up portion of the spring  42  winds when the leash  32  is extended. The spring  42  is affixed to the spring portion  56   b  at a spring joining section  58 . 
     For the purposes of promoting an understanding of the principles of the invention, reference has been made to the preferred embodiments illustrated in the drawings, and specific language has been used to describe these embodiments. However, no limitation of the scope of the invention is intended by this specific language, and the invention should be construed to encompass all embodiments that would normally occur to one of ordinary skill in the art. The particular implementations shown and described herein are illustrative examples of the invention and are not intended to otherwise limit the scope of the invention in any way. For the sake of brevity, conventional aspects of the system (and components of the individual operating components of the system) may not be described in detail. Furthermore, the connecting lines, or connectors shown in the various figures presented are intended to represent exemplary functional relationships and/or physical or logical couplings between the various elements. It should be noted that many alternative or additional functional relationships, physical connections or logical connections may be present in a practical device. Moreover, no item or component is essential to the practice of the invention unless the element is specifically described as “essential” or “critical”. Numerous modifications and adaptations will be readily apparent to those skilled in this art without departing from the spirit and scope of the present invention. 
     LIST OF REFERENCE CHARACTERS 
     
         
           10  pet leash system 
           12  case 
           14  clip 
           16  grip handle 
           17  clip holder 
           18  clip ring 
           19  grip curves 
           20  clip mating portion 
           22  clip grip protrusions with potentially pointed ends 
           24  clip pivot 
           30  grip alignment protrusions 
           32  leash 
           42  thin coil negator spring 
           44  stop mechanism 
           45  button guide 
           46  stop pivot 
           47  retaining ring 
           48  stop spring 
           50  stop spring bias mechanism 
           52  retractor button 
           54  stop release contact point 
           56  leash spool 
           56   a  leash portion 
           56   b  spring portion 
           58  spring joining section 
           59  spool spindle