Abstract:
Strap buckles for headgear can be independently adjusted by single-handed operation while the headgear is worn. To tighten the straps, the wearer pulls a strap buckle toward the chin. The adjustment preferably involves a 1:1 length-adjustment ratio, such that the strap is shortened substantially by the amount the wearer pulls on the buckle.

Description:
RELATED APPLICATION 
       [0001]    The present application claims priority to, and the benefits of, U.S. Provisional Application Ser. Nos. 60/765,144, filed Feb. 4, 2006, and 60/842,074, filed on Sep. 1, 2006, the entire disclosures of which are hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates generally to safety helmets and, in particular, to helmet straps and their adjustment. 
       BACKGROUND OF THE INVENTION 
       [0003]    Helmets for head protection are worn in a variety of environments and for various purposes. Helmets are often secured to a wearer&#39;s head by a flexible chin strap. The chin strap may include multiple segments of flexible strap material that are secured at either side of the helmet and pass below the chin, where the segments are releasably joined. In some helmets the strap segments on either side of the helmet are attached to the helmet at two positions, in front of and behind the wearer&#39;s ear. When joined, the two strap segments form a single strap that may be adjusted in length. Many of the available approaches to connecting the strap segments are cumbersome and lack security. In some cases, for example, the wearer must pass one end of the strap through a buckle or a pair of “D-rings” with a return loop, making it difficult to quickly remove the helmet in an emergency. In other cases, a quick release “snap” lacks security due to the possibility of accidental release. Two-finger release mechanisms, while more secure, typically attach to the ends of the strap segments and thus require intervening length in line with the straps. This makes it difficult to place the fastener near the chin, which can be important to the stability of the helmet. 
         [0004]    Conventional helmet straps may also be difficult to adjust. If only a single strap is provided on each side of the helmet, for example, the adjustment can be made at the buckle where the straps are joined. If the chin strap has connections at two positions on each side of the helmet, however, the two separate strap segments each need adjustment for length, but generally have no convenient buckle or termination to accommodate such adjustment. A typical approach for adjusting the length of these strap segments is to fix one end of the strap and loop the free end through a buckle or loop, returning it to a ladder-lock adjustment mechanism positioned along the length of strap. By pushing more or less of the free end through the ladder lock, the length of a strap segment is altered. The geometry of this solution dictates that for each inch of length adjustment, the free end must move two inches. The free strap end that extends beyond the ladder lock may be secured with an additional component such as a clasp, or in some designs the wearer can adjust the position of the ladder lock along the strap segment to minimize the length of the exposed strap. In any case, the result is that adjusting the length of helmet straps is neither fast nor convenient and may require removing the helmet and making multiple adjustments, repositioning the ladder lock, and trying the helmet again for proper fit. 
         [0005]    While adjustment theoretically is needed only when the helmet is first acquired, in practice the wearer may wish to adjust the tightness of the straps according to circumstances. In active situations, for example, especially if additional accoutrements such as night-vision goggles are attached to the helmet, the wearer may wish the straps to be tighter than normally required. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention provides practical and reliable solutions to the foregoing problems. In various embodiments, the invention provides a secure retention system for protective helmets that facilitates easy adjustment. For protective headgear attached in four positions, the lengths of each of the four straps can be independently adjusted without having to push or withdraw the strap ends through a buckle or ladder-lock device. In preferred embodiments, four independently adjustable straps that attach to the back of the helmet on left and right sides engage a bridging nape pad such that tightening the straps urges the nape pad forward to press against occipital lobe of the wearer&#39;s head, and this tightening may be accomplished by sliding strap buckles toward the chin. This approach is particularly well-suited to wearers who must have protective headgear in place for extended periods, because the wearer may shorten or lengthen the helmet retention straps quickly and conveniently. 
         [0007]    In general, preferred embodiments of the invention include strap buckles that can be independently adjusted by single-handed operation while the headgear is worn. To tighten the straps, the wearer pulls a strap buckle toward the chin, a direction that is natural for the wearer and efficient because it is in the direction that the wearer wants the helmet to move. The adjustment preferably involves a 1:1 pull-down ratio, such that the strap is shortened substantially by the amount the wearer pulls on the buckle. 
         [0008]    In one embodiment, a strap assembly in accordance with the invention comprises a chin-holding component; retention components at the front left and right sides of the wearer&#39;s head each comprising a forward strap connecting to the front-side of the helmet, rear left and right retention components connecting to the rear of the helmet and, desirably, an adjustment buckle as described above associated with each retention component that allows independent adjustment of the strap lengths to the chin-holding component; a nape pad engaging the rear retention components; and a releasable coupling component between the chin-holding component and retention components on at least one side of the helmet. 
         [0009]    In some preferred embodiments, the adjustment buckle includes a central cross-member to which one end of a strap segment is secured; a pair of slots parallel to the central cross-member configured so that the flexible strap can pass upward through one slot, over the central member and down through the second slot; and a finger notch or indentation area facilitating manual engagement of the buckle to slide it along the strap length. The slots of the buckle are desirably shaped such that when the buckle is in its normal orientation, they create a gripping contact with the flexible strap to inhibit the strap segment from sliding through the slots. In a second orientation, however, the gripping contact surfaces are angled to permit the strap to slide easily through the slots. Angular movement from the gripping orientation to the sliding orientation is accomplished by pinching the buckle in the finger-indentation area and pulling so as to rotate the buckle about an axis running essentially through the central cross-member. 
         [0010]    In various embodiments, the strap configuration includes a two-finger-releasable connecting device for attaching flexible strap segments. For example, a releasable two-part buckle in accordance with the invention may comprise a male component attached at one end to a flexible strap segment and having at least two fingers extending from the other end of the component, which can snap-engage a female component. The engagement can be released by simultaneously pressing the two fingers. Flush abutment between flat surfaces of the male and female components without significant intervening linear space helps maintain tension between the strap components. 
         [0011]    In a preferred embodiment, the female component of the connecting device has a pass-through area along its underside, parallel to the direction of introduction of the male component, through which a flexible strap segment is passed to terminate at a flat surface which abuts the male component. When the male and female components are joined, the two opposed, flat surfaces abut each other, thus bringing the two flexible straps substantially together without significant intervening space. In some embodiments, two V-shaped strap segments, one with its apex terminating at the flat surface of the male component and the other with its apex terminating at the flat surface of the female component, are thereby drawn into an “X” configuration that channels the tension in the straps along continuous lines, rather than allowing the tension to dissipate in an intervening length of strap. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments of the present invention are described with reference to the following drawings, in which: 
           [0013]      FIG. 1  is a side elevational view of a protective helmet secured to the wearer&#39;s head by means of the retention system of the present invention. 
           [0014]      FIG. 2   a  is rear elevational view back showing the nape pad of the present invention. 
           [0015]      FIG. 2   b  is a rear elevational view showing an alternative embodiment of the nape pad in which the back straps cross to the opposite side of the helmet. 
           [0016]      FIG. 3  is a perspective view of a strap buckle in accordance with the present invention. 
           [0017]      FIG. 4   a  is a sectional view of the strap buckle of  FIG. 3  in its normal orientation. 
           [0018]      FIG. 4   b  is a sectional view showing the strap buckle of  FIG. 4   a  rotated in orientation to allow the straps to slide. 
           [0019]      FIG. 5  is a plan view of the male and female components of a buckle in accordance with the present invention. 
           [0020]      FIG. 6  is a plan view of the buckle of  FIG. 5  in the connected position. 
           [0021]      FIG. 7  is an exploded view of the buckle of the present invention showing the flexible straps to which the male and female components are to be connected. 
           [0022]      FIG. 8  shows another embodiment of the present invention in plan view. 
           [0023]      FIG. 9  shows the two embodiments of the female component of the buckle taken from  FIG. 5  and  FIG. 8  to illustrate the critical geometry of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    With reference to  FIG. 1 , a helmet comprising a rigid helmet shell  51  is positioned on a wearer&#39;s head and secured by the retention system of the present invention. The retention system engages the wearer&#39;s chin by means of a chin holder  53 , which preferably comprises a first member  53   a , which passes below the chin, and a second member  53   b , which passes between the chin and the lower lip. The chin holder  53  is joined to retention straps using a coupling component  56 , a preferred embodiment of which is described below, although any suitable quick-disconnect fitting may be used. The coupling component  56  desirably provides a secure, two-finger-activated device that allows the retention straps to be disjoined on at least one side of the wearer&#39;s head to allow the helmet to be worn and removed. In the preferred embodiment, there is only one coupling component  56  on the left or the right side according to the wearer&#39;s preference. The coupling component  56  is shown in  FIG. 1  on the wearer&#39;s left side. Other components on the illustrated left side are found in similar positions on the right side of the retention system. 
         [0025]    As may be seen in  FIG. 1 , the retention system further comprises a forward strap  59  connected to the coupling component  56  and extending upward to the side of the helmet  51  toward the front. The forward strap on the right side or the wearer (not shown) is connected by sewing or other means directly to the chin coupling members  53   a ,  53   b . To facilitate attachment of the forward strap  59  to the helmet shell  51 , the strap passes through a slot  65   a  in a strap anchor  68   a  and loops back to a strap buckle  71   a , which is further described below. As may be seen in more detail in  FIG. 4   a , the strap anchor  68  is secured to the interior surface of helmet shell  51  with a fastener  74  (e.g., a screw), which first passes through a hole  75  in helmet shell  51  and then through a mounting hole  76  in strap anchor  68 , finally engaging a T-nut  77  or similar complementary fastening component on the inside of the helmet  51 . 
         [0026]    With renewed reference to  FIG. 1 , the rearward strap assembly comprises a first strap  62  that passes through a ring  78  and loops back to strap buckle  71   b , which is preferably identical to buckle  71   a  and will be described below. The rearward strap assembly further comprises a back strap  80   a  secured to ring  78  by looping a first end through the ring and sewing or otherwise permanently affixing this first end to back strap  80   a , as indicated at  83 . The second end of back strap  80   a  ascends and is secured through slot  65   b  of anchor  68   b . Anchor  68   b , in turn, is attached to helmet shell  51  by means of a fastener  74   b , in the same manner anchor  68   a  is secured at the front of the helmet  51 . 
         [0027]    As shown in  FIG. 2   a , a nape strap  85  is associated with a nape pad  88  to facilitate adjustment of the nape pad fit to the back of the wearer&#39;s head. One end of nape strap  85  forms a left-side loop  85   a  through which back strap  80   a  passes and the other end forms a similar right-side loop  85   b  through which back strap  80   b  passes. In the preferred embodiment, nape strap  85  includes a strap buckle  71   c , which facilitates adjustment of the distance between back strap  80   a  and  80   b . In the alternate embodiment shown in  FIG. 2   b , a nape pad  92  is formed in the shape of the letter “X” with passages for back straps  80   a ,  80   b , which cross each other and are secured to anchors  74   b ,  74   c  on opposite sides of the helmet from which they originate. The rearward strap  62  extends only to ring  78  at the edge of the nape pad  88  (or  92 ). Back straps  80   a ,  80   b , are fixed-length and are not required to slide through the nape pad when adjusting the rearward strap assembly  62  on the left side (or the similar rearward strap on the right side). 
         [0028]    With reference to  FIG. 3 , the strap buckles  71  of the present invention engage each of the two forward straps (left forward strap  59  being shown) and two rearward strap assemblies to allow independent adjustment of their lengths. The illustrated embodiment of strap buckle  71  comprises a frame  95  with slots configured so that a flexible strap can pass upward through one slot, over a central member and down through the second slot. A finger indentation area  99  is formed by an outwardly flared surface of frame  95  to facilitate engagement of the strap buckle in order to rotate it about its central member. 
         [0029]    With reference to  FIG. 4   a  and  FIG. 4   b , the strap buckle  71  includes a gripping slot  102  and a sliding slot  105 , both formed generally by the frame  95  and the central cross-member  108 . The flexible strap indicated generally at  111  passes up through sliding slot  105 , over central cross-member  108 , and then down through gripping slot  102 . Segment  111   a  of strap  111  continues beyond strap buckle  71  to anchor  68 , where it loops through slot  65  and around a pin  114 . Segment  111   b  of strap  111  returns to strap buckle  71 , passing around the central cross-member  108 , and end segment  111   c  of strap  111  is secured to itself to form a closed loop around cross-member  108  by sewing or other suitable means (as indicated at  117 ). The inwardly facing surface of finger indentation area  99  is formed with a sharp, angled surface  120  such that that when strap buckle  71  is in its normal orientation, a tensioning force on strap  111  causes angular surface  120  to press against flexible strap segment  111   a , thereby creating a frictional contact with the strap segment  111   b  and strap end  111   c . This frictional engagement resists sliding of the flexible strap  111  through the strap buckle  71 . 
         [0030]    The wearer moves the strap buckle  71  to the orientation shown in  FIG. 4   b  to adjust the length of the flexible strap  111 . In this orientation, the angular surface  120  disengages from strap  111   b  and strap end  111   c , thus allowing flexible strap  111  to slide unimpeded through the strap buckle  71 . This rotational movement from the gripping orientation of  FIG. 4   a  to the sliding orientation of  FIG. 4   b  is easily accomplished by pulling on the finger indentation area  99  to draw the upper edge of frame  95  downward, rotating the buckle about an axis running essentially through the central cross-member  108 . If the wearer combines the rotational movement described above with a downward force (as indicated by arrow “A”), the strap buckle  71  draws strap end  111   c  downward. The downward motion of strap end  111   b  (as indicated by arrow “C”), in turn, causes strap segment  111   a  to slide upward (as indicated by arrow “B”) by an equivalent amount. Since strap segment  111   a  is part of flexible strap  111 , pulling buckle  71  downward shortens the distance between the pin  114  of anchor  68  and the lower end of flexible strap  111 , which is secured at the chin holder, thereby tightening the helmet on the wearer&#39;s head. As can be seen from  FIGS. 4   a  and  4   b , the length of strap  111  is shortened exactly by the amount the wearer draws down buckle  71 , providing a 1:1 length-adjustment ratio. To loosen the retention system of the present invention, the wearer rotates the strap buckle as in  FIG. 4   b  and applies an upward force such that the arrows “A,” “B,” and “C” of  FIG. 4   b  are reversed. 
         [0031]      FIGS. 5-9  illustrate a preferred coupling component  56  in the form of an attachment buckle. With reference to  FIG. 5 , a preferred buckle  56  comprises a male component  151  and a female component  154  coupling together flexible straps comprising, with respect to male component  151 , strap segments  157   a ,  157   b , and with respect to female component  154 , strap segments  160   a ,  160   b . Male and female components  151 ,  154  are preferably molded from a strong, flexible, resilient plastic material such as Nylon or Delrin. The fingers  163   a ,  163   b  and guide member  166  are received within a receptacle area  169  of the female component  154  using normal manual pressure. During this coupling movement, fingers  163   a  and  163   b  deflect laterally toward guide member  166  until engaging features  172   a ,  172   b  have cleared surfaces  175   a ,  175   b  of the female component  154 . At this point, the flexibility of the fingers  163   a ,  163   b  cause them to return outwardly to their uncompressed position, so that surfaces  175   a ,  175   b  resist return movement of engaging features  172   a ,  172   b , thereby preventing separation of the male component  151  from the female component  154 . The female component  154  has openings  178   a ,  178   b  that afford access to fingers  163   a ,  163   b  following insertion of the male component  151  into the female component  154 . 
         [0032]    With reference to  FIGS. 6 and 7 , fingers  163   a ,  163   b  are sufficiently exposed through the openings in the female component  154  to permit the wearer to pinch the fingers and flex them inwardly, thereby freeing the engaging features  172   a ,  172   b  from surfaces  175   a ,  175   b  and allowing the male component  151  to be withdrawn from the female component  154 . A flexible intermediate strap  181  passes through a slot  179  in male component  151 , and a flexible intermediate strap  187  is secured to female component  154  through a pass-through area  187 . 
         [0033]    In the preferred embodiment, intermediate strap  181  is sewn or otherwise permanently affixed to the flexible strap components  157   a ,  157   b . As illustrated, the components  157   a ,  157   b  are part of the same single length of strap, which is folded to form a V-shaped configuration. Alternatively, however, components  157   a ,  157   b  can be separate strap segments that are joined to form the same configuration. In either case, the apex of the V is substantially aligned (i.e., flush) with the abutment face  190  of male component  151 , which, when the male and female components are locked, makes contact with a complementary abutment surface surface  193  of the female component  154 . As a result, the edges of the V-shaped straps at their apices are substantially in contact along the entire apex edge length. 
         [0034]    Similarly, the pass-through area  184  in the female component accepts intermediate strap  187 , which is sewn or otherwise affixed to strap segments  160   a ,  160   b  and positioned so that the apex of the V is substantially flush with the abutment surface  193 . The pass-through area  184  is oriented parallel to the direction of introduction of the male component  154 , and locates the tensioning region of the strap segments  160   a ,  160   b  adjacent the front surface  193  of the female component  154 , very close to the point where the female component joins the male component. 
         [0035]    It is also possible to utilize the invention with single linear strap segments rather than V-shaped segments. In this case, the male component  151  may be connected to one of the single straps directly through the slot  179  instead of employing the intermediate strap  181 , and the female component  154  may be connected directly to the other single strap using the pass-through area  184 , thereby obviating the need for the intermediate strap  187 . Another alternative is to use one free, single strap and one V-shaped strap, in which case it is advantageous for the male component  151  to be connected to the single strap directly through the slot  179  and the female component  154  to be connected to the V-shaped strap via intermediate strap  187 . 
         [0036]      FIG. 8  illustrates another embodiment  154 ′ of the female component. The component  154 ′ has many of the same features as the female component  154  shown in previous figures, including receptacle area  169 , surfaces  175   a ,  175   b , and openings  178   a ,  178   b  which cooperate with features of the male component  151  as described previously. Straps  160   a ,  160   b  are attached to the component  154 ′ via mounts such as the slots  195   a ,  195   b . This embodiment is particularly well suited to applications where two straps are joined at the female side with one or two straps on the male side. 
         [0037]      FIG. 9  shows how both female components  154  and  154 ′ share the critical geometry that allows tension to pass through the buckle without being dissipated by intervening linear space. The dotted lines A-A′ and B-B′ follow the tension in the flexible straps  160   a ,  160   b  respectively. The slots  195   a ,  195   b  are angled toward each other so that the lines of tension A-A′ and B-B′ intersect each other at or very near the front surface  193  of the female component. As can be seen in  FIG. 9 , both embodiments  154  and  154 ′ of the female component provide this geometry. When the male and female components are engaged, these lines of tension are substantially continuous—that is, the lines A-A′ and B-B′ shown in  FIG. 9  are substantially congruent with complementary lines from the V-shaped strap of the male component. This is because when the male and female portions of the buckle are locked, the V-shaped straps come together to form the letter “X,” so that tension in the opposed straps are aligned. This has been found to substantially improve helmet stability. 
         [0038]    With renewed reference to  FIG. 1 , the straps of the chin-holding component  53  are joined to the male component of the buckle  56 . The straps  59  and  62  are joined, as described above, to the female component of the buckle  56 . When the male component of buckle  56  is inserted into the female component, the strap segments  53   a ,  53   b ,  59 , and  62  abut to form the letter “X” because the buckle does not occupy significant space between them. The result is improved stability of the helmet  51  with respect to the wearer&#39;s head. 
         [0039]    Having described certain embodiments of the invention, it will be apparent to those of ordinary skill in the art that other embodiments incorporating the concepts disclosed herein may be used without departing from the spirit and scope of the invention. The described embodiments are to be considered in all respects as only illustrative and not restrictive.