Abstract:
The present invention provides a heating pad capable of rapid initial heat transfer to a heating pad member by means of a removable gel pack member which is releasably attached to the heating pad member. The heating pads of the present invention are useful for the rapid and convenient treatment of various muscular and orthopedic aches and pains.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to improvements in heating pads and particularly to heating pads having removable gel packs which provide a rapid warming capability. 
     The value of heat treatment for easing and preventing the onset of pain in muscle tissues is well established. For example, muscles which tend to cramp may be heated before strenuous exercise to enrich the blood supply to the appropriate areas. Means for effecting such heat treatment include the use of electrical heating pads. However, conventional heating pads used in treating patients in need of heat therapy suffer from several inconveniences. Slow heat-up times result from increased padding which is often used to improve comfort by providing more even heat distribution. Speeding heat-up by increasing electrical current or reducing the padding filler typically causes uncomfortable and potentially dangerous localized hot spots. An enhanced design which permits rapid initial transfer of heat to a subject prior to the time regular I 2 R heating can achieve a similar heat transfer would avoid the delay in providing treatment using standard heating pads. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide an improved heating pad comprising a heating pad member and a removable gel pack which can be rapidly heated to a desired temperature prior to attachment to a heating pad member. 
     Another object of the present invention is to provide a heating pad which is capable of rapid heating with increased comfort using standard wattage and padding thicknesses. 
     Accordingly, the present invention provides a heating pad for a subject in need of heat therapy comprising a heating pad member comprising a cover and electrical heating coils, wherein the cover comprises an inner layer and an outer layer, and a removable gel pack member which contacts an anatomical portion of the subject and is releasably attached to the inner layer, wherein each layer comprises a flexible fabric material and has a plurality of sides which are permanently secured together, and wherein the removable gel pack member comprises a heat-retentive gel. The electrical heating coils are enclosed by the cover and are substantially evenly distributed within the cover. The present invention conveniently permits preliminary heating of the gel pack member to a predetermined temperature prior to attachment to the inner layer, and additionally permits the maintenance of the predetermined temperature during application of the heating pad to the subject by operating the electrical heating coils. 
     The accompanying drawings, referred to herein and constituting a part hereof, illustrate preferred embodiments of the present invention and, together with the description, serve to explain the principles of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an embodiment of a heating pad with removable gel pack in accordance with the present invention. 
     FIG. 2 is a perspective view of an embodiment of a heating pad with removable gel pack removed in accordance with the present invention. 
     FIGS. 3A,  3 B and  3 C are top, side cross-sectional and top cross-sectional diagrammatic views of an embodiment of a heating pad with removable gel pack in accordance with the present invention. 
     FIG. 4 is a side perspective diagrammatic exploded view of an embodiment of a heating pad with removable gel pack in accordance with the present invention. 
     FIGS. 5A,  5 B and  5 C are top diagrammatic view and cross-sectional side diagrammatic views with detail of an embodiment of a heating pad with removable gel pack in accordance with the present invention. 
     FIGS. 6A,  6 B and  6 C are top diagrammatic and side cross-sectional views with detail of a removable gel pack in accordance with the present invention. 
     FIGS. 7A and 7B are top diagrammatic and cross-sectional exploded side diagrammatic views of Velcro™-type hook and loop patches in accordance with the present invention. 
     Other features and advantages of the present invention will be apparent from the following description of the preferred embodiments thereof, and from the claims. 
    
    
     In order that the present invention may be readily understood, embodiments thereof will now be described, by way of example, with reference to the accompanying drawings. 
     DETAILED DESCRIPTION 
     In accordance with the exemplary embodiment illustrated in the drawings, the heating pad of the present invention includes a heating pad member  10  and a removable gel pack member  12 . Heating pad member  10  is made up of a cover  13 , padding  17  and electrical heating coils  18 . The cover  13  comprises a first layer  14  and a second layer  15 . The first layer  14  is an inner layer which contacts substantially the entire outer layer  21  of the gel pack member  12  and provides the interface through which thermal energy passes to the gel pack member  12 , and the second layer  15  is an outer layer which provides the exterior surface of the heating pad. Each layer  14  and  15  comprises a flexible fabric material having a plurality of sides which are permanently secured together by means known in the art, for example, by stitching, riveting or stapling. Dispersed uniformly within the cover are padding  17  and the electrical heating coils  18  which are connectable to a suitable power source. The padding  17  consists of the typical filler materials used in heating pads, typically made from a nonflammable fiber or other flame-resistant or flame-retardant materials. 
     The removable gel pack member  12  is releasably attached to the second layer  14  of the heating pad cover  13 , and comprises a heat-retentive gel which, in the practice of the subject invention, is heated to a predetermined temperature prior to attachment. In an exemplary embodiment of the present invention, the removable gel pack  12  contacts and covers substantially the entire inner layer  14  of the cover  13  of the heating pad member  10 . The gel pack member  12  is typically constructed from two sheets ( 21  and  22 ) of a thin liquid-impermeable flexible plastic, such as vinyl or polyethylene. The outer layer  21  contacts substantially the entire inner layer  14  of the heating pad member  19 , and provides the interface through which thermal energy flows from the removable gel pack  12  to the heating pad member  10 . In an exemplary embodiment, the inner layer  22  of the removable gel pack  12  provides the interior surface of the heating pad. Thus, when the gel pack is placed in substantial contact with an anatomical portion of subject in need of heat therapy, heat is transferred to the subject through the interface formed by inner layer  22 . The inner and outer sheets  22  and  21  are sealed along their edges by means known in the art, such as thermal welding or sealing, and as such form a leak-proof container for the gel. In addition, the gel pad member  12  may optionally have a temperature indicator  24 , such as a tape containing an indicating temperature-sensitive liquid crystal substance, which would visually indicate to the user that the gel pack member  12  has been heated to an excessive temperature for normal use in a heating pad. 
     In an exemplary embodiment of the present invention, the removable gel pack member  12  is attached to the heating pad member by two pairs of Velcro™-type hook and loop fasteners located respectively in complementary positions on the heating pad member and the removable gel pack (FIG.  3 ). Thus, the first layer  21  is modified by permanent attachment of at least one fastener  19  which may, for example, be of a hook or loop type, such as Velcro™, placed in position(s) so as to fasten to complementary fasteners  20  positioned on the inner layer  14  of the heating pad member  10  and thereby to stably attach the removable gel pack  12  to the heating pad member  10 . The fasteners  19  and  20  are permanently attached by any method known in the art, such as by stitching, sewing, gluing, welding, riveting, etc. 
     In an alternative exemplary embodiment, an optional outer layer  21   a  and an optional inner layer  22   a  made from a plastic, nylon, vinyl or natural fiber fabric provide a protective cover for the gel pack member  12 , wherein the outer and inner layers  21   a  and  22   a  are sealed along their peripheral edges by means known in the art, such as thermal welding or sealing, so as to form a pocket open on one side in which the gel pack member may be inserted during use. In this embodiment, heat is transferred to the subject through the interface formed by inner layer  22   a . Accordingly, the outer layer  21   a  of the protective cover is modified by permanent attachment of at least one fastener  19  placed in position(s) so as to fasten to complementary fasteners  20  positioned on the inner layer  14  of the heating pad member  10 . Such modification of outer layer  21   a  is useful in embodiments wherein a cutout is present corresponding substantially in location and dimension with each of the fasteners  19  and  20 . In the latter embodiment, the gel pack  12  is maintained in stable position with respect to the heating pad member  10  by means of the releasably attached pocket formed by outer and inner layers  21   a  and  22   a . As thus embodied, inner layer  22   a  provides the interior surface of the heating pad. The gel pack member  12  is maintained stably in the pocket during use by any means known in the art, including by friction between the gel pack member and the protective cover, a stabilizing fastener, clasp, hook/loop fasteners, etc., capable of releasably sealing the remaining open side, etc. In another embodiment, the ensemble of both the gel pack member  12  attached to the heating pad member  10  may be contained in a suitably shaped cover made from polyester, cotton, nylon or mixed fiber fabric. Such a cover may be releasably sealed by any means known in the art such as a clasp, loop/hook means or button. 
     Referring to FIGS. 3,  5  and  6 , the hook or loop fasteners  19  and  20  may be located at portions of the gel pack member  12  where the two layers  21  and  22  comprising the major sides of the gel pack are adjoined flush to one and other so as to form a unified plane  23  and to exclude the gel contents at the junction surface. These layers are adjoined by means known to those skilled in the art, including by means of thermal welding or epoxy gluing. The junction so formed should be capable of withstanding the typical thermal and mechanical stresses expected for the removable gel pack  12 . 
     Referring to FIG. 3, the removable gel pack member  12  may be heated using any means consistent with the materials of which the gel pack is constructed. Most conveniently, the gel pack may be heated in a microwave oven to a predetermined temperature. Heating using a thermal heater such as under an infrared heater and in boiling water are alternative methods of heating the removable gel pack member  12  for use in the present invention. 
     In practice, the predetermined temperature is substantially maintained during application of the heating pad  10  to a portion of the anatomy of the subject after attachment of the gel pack  12  by passing a regulated current through the electrical heating coils  18 . The electrical heating coils  18  are typically composed of metallic resistance wire or a conducting polymeric wire. The current useful for operating the electrical heating coils  18  may be of the alternating current type, such as 120V/60 Hertz household current, for operation in the home or workplace, or of the direct current type, such as 12V current, for convenient portable operation using a battery pack or in a vehicle, such as an automobile. After attachment of the removable gel pack  12  and the consequent rapid thermal transfer, the operating temperature can be maintained, raised or lowered for therapeutic relief or patient comfort by adjusting a suitable voltage controller (not shown) with or without automatic control mechanisms, including off-on proportional timers or thermostats. 
     One of skill in the art will readily understand that the present invention is not limited to the specific embodiments shown and described, and may be further used in applications other than therapeutic heating pads, such as heated bandages, stents, supports, etc. 
     Variations of the present invention may be made which are within the scope of the present invention as defined in the accompanying claims, without departing from the principles of the present invention. 
     Referring to FIGS. 3,  5  and  6 , the hook or loop fasteners  19  and  20  may be located at portions of the gel pack member  12  where the two layers  21  and  22  comprising the major sides of the gel pack are adjoined flush to one and other so as to form a unified plane  23  and to exclude the gel contents at the junction interface. (FIG. SC) These layers are adjoined by means known to those skilled in the art, including by means of thermal welding or epoxy gluing. The junction so formed should be capable of withstanding the typical thermal and mechanical stresses expected for the removable gel pack  12 . 
     Referring to FIG. 3, the removable gel pack member  12  may be heated using any means consistent with the materials of which the gel pack is constructed. Most conveniently, the gel pack may be heated in a microwave oven to a predetermined temperature. Heating using a thermal heater such as under an infrared heater is an alternative method of heating the removable gel pack member  12  for use in the present invention. 
     In practice, the predetermined temperature is substantially maintained during application of the heating pad  10  to a portion of the anatomy of the subject after attachment of the gel pack  12  by passing a regulated current through the electrical heating coils  18 . The electrical heating coils  18  are typically composed of metallic resistance wire or a conducting polymeric wire. The current useful for operating the electrical heating coils  18  may be of the alternating current type, such as 120V/60 Hertz household current, for operation in the home or workplace, or of the direct current type, such as 12V current, for convenient portable operation using a battery pack or in a vehicle, such as an automobile. After attachment of the removable gel pack  12  and the consequent rapid thermal transfer, the operating temperature can be maintained, raised or lowered for therapeutic relief or patient comfort by adjusting a suitable voltage controller (not shown) with or without automatic control mechanisms, including off-on proportional timers or thermostats. 
     One of skill in the art will readily understand that the present invention is not limited to the specific embodiments shown and described, and may be further used in applications other than therapeutic heating pads, such as heated bandages, stents, supports, etc. 
     Variations of the present invention may be made which are within the scope of the present invention as defined in the accompanying claims, without departing from the principles of the present invention.