Abstract:
A hearing protective device that includes a first ear cup, a second ear cup, and a headpiece. The first ear cup is maintained in a fixed position in the first end of the headpiece through a frictional engagement, and the second ear cup is maintained in a fixed position in the second end through a frictional engagement. The hearing protection device is beneficial in that the user can easily change the ear cup if damaged or if a different level of sound attenuation is desired. The user does not have to buy a whole new earmuff apparatus.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The invention relates to maintaining ear cups in a headband through a frictional engagement.  
         [0002]     Hearing protective devices in the form of earmuffs are widely used in industry to protect workers against environmental noise. Traditional hearing protective earmuffs include a pair of cup-shaped rigid shells that are attached to a headband. The headband is commonly designed for permanent attachment to the ear cups. For these constructions, an attempt to remove the ear cup from the headband can damage or destroy the ear cup, the headband or both.  
         [0003]     Some hearing protective earmuff configurations are designed to allow the ear cup to be removed from the headband. In these constructions, mechanical mechanisms such as male-female connectors, prongs, screws, nuts, and bolts can be used to secure and separate the headband and ear cups. These mechanisms often involve relatively difficult manipulations of the connection mechanism or may require additional tools to separate the ear cup from the headband.  
       SUMMARY OF THE INVENTION  
       [0004]     This invention features a hearing protective earmuff device that includes a first ear cup, a second ear cup, and a headpiece. The headpiece has first and second ends extending therefrom. The first ear cup is maintained in a fixed position in the first end through a frictional engagement. The second ear cup is also maintained in a fixed position in the second end through a frictional engagement  
         [0005]     The invention features a hearing protective device in which the headband terminates in ends that are capable of maintaining ear cups therein through a frictional engagement between the ear cup and the end. In some embodiments, the nature of the ends of the headband permits the headband to be worn in multiple positions on the head including, e.g., behind the neck, while maintaining the earmuffs in proper position on the ears.  
         [0006]     The invention also features a hearing protective device in which the frictional engagement that exists between the ear cup and the headband allows a user to insert and remove the ear cup from the headband as desired without damaging the ear cups or the headband. The ability of the headband to releasably retain the ear cups facilitates ear cup removal and replacement for a variety of situations including, e.g., when the earmuffs have become damaged or soiled or when a level of sound attenuation is not appropriate for the environment in which the hearing protection device will be used. The earmuffs can be replaced with a second set of earmuffs that provide the requisite sound attenuation.  
         [0007]     The invention is also beneficial in that the ear cups can be retained on the headband without the use of additional affixing mechanisms such as adhesives, screws, bolts, and snaps, although such mechanisms can optionally be included.  
         [0008]     Other features and advantages will be apparent from the following description of the drawings, the preferred embodiments, and from the claims.  
       GLOSSARY  
       [0009]     The term “frictional engagement” means that resistance to movement exists and that the resistance is such that an external force is required to achieve movement.  
         [0010]     The term “headband” means a device constructed to retain an earmuff and assist in compressing an earmuff against the head of a user.  
         [0011]     The term “ear cup” means a component that is dimensioned to receive an ear of a user and that is constructed to provide sound attenuation. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a plan view of a headband that includes ends that terminate in a C-shaped hook.  
         [0013]      FIG. 2  is a plan side view of an end of a headband in the form of a curved hook.  
         [0014]      FIG. 3  is a plan side view of an end of a headband in the form of a square hook.  
         [0015]      FIG. 4  is a plan side view of an end of a headband in the form of a rectangular hook.  
         [0016]      FIG. 5  is plan side view of an end of a headband in the form of a hexagonal hook.  
         [0017]      FIG. 6  is plan side view of an end of a headband in the form two parallel tines.  
         [0018]      FIG. 7  is plan side view of an end of a headband in the form of a rectangular hook and a portion of an ear cup positioned in the opening defined by the hook.  
         [0019]      FIG. 8  is plan side view of an end of a headband in the form of a square hook and a portion of an ear cup positioned in the opening defined by the hook.  
         [0020]      FIG. 9  is a side view of a hook-shaped end of a headband and a circular portion of an ear cup positioned in the opening defined by the hook.  
         [0021]      FIG. 10  is a side view of a hook-shaped end of a headband and an octagonal portion of an ear cup positioned in the opening defined by the hook.  
         [0022]      FIG. 11  is a perspective view of an embodiment of a headband that includes ends that terminate in two parallel tines.  
         [0023]      FIG. 12  is a front view of the headband of  FIG. 11 .  
         [0024]      FIG. 13  is a front view of a hearing protective device that includes the headband of  FIG. 1 .  
         [0025]      FIG. 14  is a side view of an end of a headband and an ear cup positioned in the end according to another embodiment.  
         [0026]      FIG. 15  is a perspective view of a hearing protective device according to another embodiment. 
     
    
       [0027]     Like reference symbols in the various figures of the drawing indicate like elements. The elements in the drawings are not to scale.  
       DETAILED DESCRIPTION  
       [0028]      FIG. 1  illustrates a hearing protective device  10  that includes a headpiece  8  and earmuffs  15   a ,  15   b  that include an ear cup  16   a ,  16   b  and a cushion  17   a ,  17   b . The headpiece may be in the form of a headband that includes a generally U-shaped band that terminates in two ends  14   a ,  14   b , each of which is capable of maintaining an ear cup  16   a ,  16   b  positioned therein through a frictional engagement. The frictional engagement between the ear cups  16   a ,  16   b  and the ends  14   a ,  14   b  allows the ear cups to be maintained in a fixed position on the headband without assistance from another source. The frictional engagement can be achieved in various ways including, for example, having the portion of the ear cup that is received by the headband being sufficiently larger than the opening in the ear cup receiving end of the headband. The resistance exhibited by the frictional engagement can be increased by increasing the size of the ear cup or by decreasing the size of the ear cup receiving portion of the headband (relative to one another). At least one of the ear cup or the end can partially deform to accommodate the other and to achieve the frictional engagement.  
         [0029]     The ends of the U-shaped headband are shaped and dimensioned to receive an ear cup, and to maintain the ear cup in a fixed position on the headband through a frictional engagement with the ear cup. The ends can also optionally be shaped and dimensioned to releasably retain the ear cup therein and to permit the insertion and removal of an ear cup without damaging the ear cup or the end. The ear cups  16   a ,  16   b  remain in a fixed position in the ends  14   a ,  14   b  until moved or removed by the user.  
         [0030]     The hearing protective device  10  can be assembled by sliding the ends  14   a ,  14   b  of the headband  8  around the ear cups  16   a ,  16   b  to frictionally engage the ear cups  16   a ,  16   b  or by inserting the ear cups  16   a ,  16   b  in the ends  14   a ,  14   b . The headband can be configured to be capable of assuming a variety of positions including, e.g., being positioned under the user&#39;s chin, behind the user&#39;s neck, and combinations thereof. In some embodiments, the headband position can be altered by constructing the headband and ear cup such that the headband can rotate about the ear cup from a first position to a second position. In such embodiments, the user can rotate the ends  14   a ,  14   b  about the ear cups  16   a ,  16   b  to achieve a desired headband orientation and position.  
         [0031]     In some embodiments, the ear cup  16  includes a channel  44   a ,  44   b  for receiving an end  14  of the headband. The channel  45  is defined by two side walls  43   a ,  43   b  and a bottom wall  45  extending from a first side wall  43   a  to a second side wall  43   b . The shape defined by a cross section of the ear cup taken at the bottom wall  45  of the channel  44   a  and the dimension thereof corresponds to the opening defined by the end of the headband such that when the ear cup is positioned in the opening defined by the end of the headband the ear cup remains in position therein through a friction fit. The shape defined by the bottom wall of the channel can correspond to or be different from the shape of the opening defined by the interior wall(s) of the ear cup receiving end of the headband. The shape defined by or partially defined by the interior, ear cup receiving wall(s) of the end of the headband can be different from the shape defined by the cross section of the ear cup taken at the bottom wall of the channel. The bottom wall of the channel can define any of a variety of shapes including, e.g., circle, oval, ellipse, and polygon including, e.g., triangle, square, pentagon, hexagon, heptagon, octagon, nonagon, and decagon.  
         [0032]     The ear cup is dimensioned to receive the ear of a user. The ear cup is generally cup-shaped such that the distal exterior surface is generally arcuate in shape and the proximal exterior surface, i.e., the surface closest to the ear, is generally concave and provides an open region in which the ear of a user can reside. The ear cup may be made of any suitable material, now existing or later developed. The ear cup can include a material capable of attenuating sound. Useful sound attenuating materials include gas filled cellular materials that exhibit acoustic attenuation, mechanical stiffness and formability (e.g., the ability to alter the material, e.g., by cutting, shaping, molding, or a combination thereof). Examples of useful gas filled cellular materials include, e.g., foams (e.g., closed cell foams, open cell foams, slow recovery resilient foams (e.g., pressure molded slow recovery resilient foams), instantaneous recovery foams), bonded fiber structures, aerogels, acoustic composite materials including, e.g., hollow ceramic particles in a matrix of synthetic resin binder, multiple layered acoustic composite materials, and combinations thereof. Examples of suitable cellular bonded fiber structures are described in U.S. Pat. No. 5,841,081 and incorporated herein. Examples of aerogels are described in U.S. Pat. Nos. 4,954,327 and 6,598,358 and incorporated herein. Examples of suitable acoustic composite materials are described in U.S. Pat. Nos. 5,813,180 and 5,688,860 and incorporated herein. The cellular material may be an open cell foam. The foam can be a hard foam, a semi-rigid foam, or a flexible foam.  
         [0033]     The cells of the foam can have a relatively larger average cross-sectional area at the interior of the foam, and a relatively smaller average cross-sectional at the exterior surface of the foam. The presence of smaller cells at the exterior surface of the ear cup provides a more rigid, stiff exterior layer relative to the interior foam. In some embodiments, the compacted smaller cells at or near the exterior surface of the ear cup form an integral skin on the ear cup, e.g., a film layer that results from the molding process, at the surfaces of the ear cup. The integral skin essentially includes closed cells and can include some open cells to allow the release of gas, e.g., air. Altering various parameters of the manufacturing process can alter the thickness of the integral skin. The mold temperature, for example, can influence the presence and nature of the integral skin. In some foam molding process a relatively thinner skin is formed with increasing temperatures, whereas a thicker, relatively denser skin forms at lower temperatures. One example of a useful mold temperature range for forming an integral skin is from about 35° C. to about 70° C. The integral skin can have any desired thickness. One example of a useful range of skin thickness is from about 1 mm to about 5 mm.  
         [0034]     Useful compositions from which the foam can be formed include, e.g., polyurethanes, polyvinyl chloride, and combinations thereof. Suitable hard polyurethane foams can be from polyols having a molecular weight less than 800. Suitable semi-rigid polyurethane foams can be formed from polyols having a molecular weight from about 800 to 2000, and suitable flexible polyurethane foams can be formed from polyols having a molecular weight greater than 2000. Useful foams can have any desired density including, e.g., a density ranging from about 200 kg/m 3  to about 1100 kg/m 3 , or even from about 200 kg/m 3  to about 800 kg/m 3 . Suitable foams and methods of making the same are also described, e.g., in U.S. Pat. No. 5,979,451 and incorporated herein.  
         [0035]     The sound attenuating material can optionally include a coloring agent, e.g., dye, pigment and combinations thereof. The coloring agent can provide a desired aesthetic property, a visible indication of the sound attenuation properties the ear cup, and combinations thereof. The ear cups can also optionally include other indicia of the level of sound attenuation provided thereby including, e.g., markings, colorings, and combination thereof.  
         [0036]     Alternatively or in addition the ear cups can include markings in various forms including, e.g., logos, colors, designs, imprints, relief, and combination thereof.  
         [0037]     A cushion  17   a ,  17   b  is present on the earmuffs  15   a ,  15   b  of  FIG. 13 . A cushion seals the earmuff around the ear of the user and dampens the pressure exerted by the hearing protective device against the user&#39;s head. The cushion is preferably annular such that it defines an aperture that accommodates the ear of a user. Useful cushions define a generally rectangular shape with four concave corner segments and four connecting segments defining the aperture. Alternatively, the cushion can be of any suitable shape including, e.g., oval, round, square and rectangular, and can define an aperture having any suitable shape including, e.g., oval, round, square and rectangular. The cushion can be an integral unitary member of the earmuff, e.g., formed simultaneously with the ear cup, or it can be a separate component.  
         [0038]     Useful cushions include a cellular material examples of which are set forth above and incorporated herein. Foams suitable for the cushion include, e.g., the foams set forth above including, e.g., closed cell foams, open cell foams, and combinations thereof. The foam for the cushion preferably exhibits viscoelasticity, high resiliency, or a combination thereof. Useful foam compositions include, e.g., polyurethanes, polyvinyl chloride, and combinations thereof. Preferably the foam of the cushion exhibits instantaneous recovery.  
         [0039]     The cushion can optionally include an integral skin as described above with respect to the foam ear cup.  
         [0040]     Alternatively or in addition, the cushion can include a covering, e.g., a cover, a layer, a film, a coating, and combinations thereof. A covering can protect the integrity of the foam, inhibit soiling of the foam, and enhance the cleaning properties of the cushion. The covering can also provide aesthetic appeal to the cushion including, e.g., texture, color, and combinations thereof. The covering can be continuous or discontinuous. Preferably the covering is present on the foam such that air is allowed to release from the foam. To facilitate release of air, the covering can include micro holes (e.g., puncture holes) or cracks of a size sufficient to allow release of air from the foam. Alternatively the covering can include a single hole of a size sufficient to allow the release of air to conform the cushion to the surface of the user with which it is in contact. The covering can be in the in the form of a film (e.g., a self-supporting film), woven (e.g., fabric) or nonwoven web, and comprised of any suitable composition including, e.g., synthetic polymer, natural polymer, and combinations thereof.  
         [0041]     The headband is generally U-shaped and sufficiently resilient to allow the open end of the U to be splayed apart to fit the device to the head of the user. When the device is in place on the user&#39;s head the recovery forces generated in the strained headband bias the earmuffs inwardly against the user&#39;s head and foster secure attachment and good acoustic sealing of the earmuffs to the user&#39;s head. Various headband configurations are suitable. The headband can be relatively thin and include at least one band, an example of which is illustrated in  FIGS. 1 and 13 .  
         [0042]     The headband can be adjustable in length. Mechanisms for making headbands adjustable in length are well known in the art and include, e.g., a pair of overlapping sliding members with mechanisms for maintaining the members in alignment and mechanisms for securing the overlapped portions at the desired length, a pair of telescoping nested members having mechanisms to secure the nested portions together at the desired length, and a central headband of fixed length that includes a mechanism, e.g., cooperative rack-and-pinion, toothed, interrupted thread or a combination thereof, whereby each end of the headband can be separately adjusted relative to the central headband and secured at the adjusted length. One example of a useful adjustable headband is present in product number 1440 from 3M Company (St. Paul, Minn.).  
         [0043]     The headband can be made from any suitable material. Useful headband materials include, e.g., plastic, and metal, e.g., spring steel, copper-beryllium alloys, composites, and combinations thereof. Useful plastic materials include, e.g., thermoplastic polymers (e.g., polypropylene, polyethylene, polyamide, e.g., nylon, polyester, and combinations thereof), thermoplastic elastomers, thermoset polymers, and combinations thereof. Useful composites include a polymer matrix and a filler including, e.g., fibers, particulate, and combinations thereof. The surface of an end of the headband that engages an earmuff can be treated to increase its coefficient of friction. Useful surface treatments include, e.g., texturizing (e.g., abrading the surface), coating the surface (e.g., with a composition, particles, and combinations thereof), overmolding (e.g., with a thermoplastic elastomer), and combinations thereof. One useful headband construction includes an end that includes an elastomer (e.g., natural rubber or synthetic elastomer) disposed on (e.g., overmolded on) a thermoplastic or thermoset base.  
         [0044]     The ear cup can optionally include a rigid outer shell.  
         [0045]     Although the ends  14   a ,  14   b  of the headband illustrated in  FIGS. 1 and 13  form a C-shaped hook, the ends  14   a ,  14   b  of the headband can terminate in any shape or form suitable for releasably retaining an ear cup therein through a frictional engagement with the ear cup. For example, the ends  14   a ,  14   b  can be defined by any number of side walls, which at least partially define a variety of configurations including, e.g., a letter (e.g., J, U, C, V, and D), loop, spiral (e.g., curlicue), circle, oval, ellipse, polygon including, e.g., a triangle, square, pentagon, hexagon, heptagon, octagon, nonagon, and decagon.  
         [0046]      FIGS. 2-5 ,  7 - 10  and  11  illustrate a variety of hook-shaped configurations.  FIG. 2 , for example, illustrates an end of a headband in the form of a smooth curved backward J-shaped hook. A hook-shaped end that includes three sidewalls that partially define a square-shaped opening is shown in  FIG. 3 . A hook-shaped end in the form of a partial rectangle defined by three side walls is shown in  FIG. 4 . A hook-shaped end that includes six side walls partially defining a octagonal-shaped opening is shown in  FIG. 5 .  
         [0047]     The ends of the headband can also terminate in parallel tines  20   a ,  20   b , as illustrated in  FIGS. 6, 11  and  12 . In some embodiments, the tines  20   a ,  20   b  extend downward away from the crown of the headband. In other embodiments the tines  22   a ,  22   b  extend upward toward the crown  24  of the headband  30 , as shown in  FIGS. 11 and 12 .  
         [0048]      FIG. 7  illustrates an embodiment of the hearing protective device in which a rectangular portion  46  of an ear cup is positioned in the partial rectangular-shaped opening defined by the rectangular hook-shaped end  48  of the headband.  
         [0049]      FIG. 8  illustrates an embodiment of the hearing protective device in which a square portion  50  of an ear cup is positioned in the partial square-shaped opening defined by the square hook-shaped end  52  of the headband.  
         [0050]      FIG. 9  illustrates an embodiment of the hearing protective device in which a circular portion  56  of an ear cup is positioned in the hook-shaped end  54  of the headband. Arrow A-A indicates the direction of movement of the ear cup when the ear cup is placed in and removed from the hook-shaped end of the headband. Arrow B-B indicates a rotational direction of movement that the hook  54  may undergo when the user exerts a force on the hook  54  while holding the ear cup  56  in a stationary position so as to rotate the hook  54  relative to the ear cup  56 . The circular shape of the portion of the ear cup residing in the opening formed by the hook  54  permits a relatively smooth rotation of the hook about the ear cup relative to a more ratchet-type movement that can exist when the portion of the ear cup held by the end has linear side walls.  
         [0051]      FIG. 10  illustrates an embodiment of the hearing protective device in which an octagonal portion  60  of an ear cup is positioned in a hook-shaped end  62  of a headband. Arrows C-C indicate the direction of movement through which the ear cup travels when the ear cup is inserted in and removed from the hook-shaped end of the headband. The ear cup can also be moved in the direction of C-C to position the ear cup as desired on the user&#39;s head, which effectively lengthens and shortens the headband. Arrows D 1 -D 1 , D 2 -D 2  indicate the rotational direction of movement of the hook about the ear cup. The octagonal shape of the ear cup can result in a ratcheted-type rotation of the hook about the ear cup.  
         [0052]      FIG. 14  illustrates an embodiment of the hearing protective device in which the interior walls of an end  70  of the headband form a surface that includes a series of rounded protuberances  72  and the ear cup  74  positioned in the end includes a complimentary series of rounded protuberances  76  on the surface thereof. The configuration allows a ratcheting-type rotation of the end about the ear cup when a force is applied to the end or the ear cup to rotate one of the end or the ear cup relative to the other.  
         [0053]      FIG. 15  illustrates another embodiment of the hearing protective device  100  in which the headpiece  102  is a head covering in the form of a helmet. The ends  104   a ,  104   b  of the headpiece are affixed to the exterior surface of the helmet  102  and extend from the helmet  102  to the ear of a user. Earmuffs  106   a ,  106   b  are positioned in an opening in the ends  104   a ,  104   b  and the ends  104   a ,  104   b  bias the earmuffs  106   a ,  106   b  inwardly against the user&#39;s head. The ends are moveable between a first position in which they are biased against the user&#39;s head and a second position in which they are held away from the user&#39;s head. Examples of mechanisms that attach an extension to a helmet and permit movement of the extension from a first position to a second position can be found in U.S. Pat. No. 5,546,610 and incorporated herein.  
         [0054]     Although the device has been described as having a frictional engagement between an end and an ear cup, the frictional engagement can exist with any part of the earmuff including, e.g., the cushion.  
         [0055]     All patents and patent applications cited above including those in the Background section are incorporated into this patent application in total.  
         [0056]     The invention may take on various modifications and alterations without departing from its spirit and scope. Accordingly, this invention is not limited to the above-described but is to be controlled by the limitations set forth in the following claims and any equivalents thereof.  
         [0057]     This invention also may be suitably practiced in the absence of any element not specifically disclosed herein.