Patent Publication Number: US-2006008185-A1

Title: Fastening strips with barbed closure elements

Description:
FIELD OF THE INVENTION  
      The present invention relates to interlocking closure strips, and more particularly, an interlocking fastening strip that includes at least one barbed closure element particularly adapted for use with reclosable plastic storage bags.  
     BACKGROUND OF THF INVENTION  
      Known closure fastening devices used in conjunction with thermoplastic reclosable containers provide an effective seal of the contents in the container when the fastening device is placed in a closed position. Such fastening devices typically comprise a pair of complementary closure strip elements that extend longitudinally along the upper portions of opposed sidewalls of the containers. The closure elements are constructed such that they interlockingly engage with each other in a closed or occluded position, while at the same time permitting relatively easy disengagement of the closure elements when the container is opened from the outside.  
      One desirable feature of many such fastening devices is that they enable the user to determine the state of closure of the fastening device. For example, one known arrangement provides a visual indication of the closure state of the fastening device with the use of various colorations of the opposed closure elements. One such arrangement is disclosed in U.S. Pat. No. 4,829,641. When the opposed closure elements are interlocked, the user perceives a third distinct coloration of overlapping element portions indicative of proper closure of the container.  
      Other conventional techniques utilize a particular tactile “feel” provided to the user of the container to indicate closure of the container. For example, U.S. Pat. No. 5,070,584 discloses a zipper arrangement that provides the perception of a “bumpy” feel. The zipper arrangement includes a pair of opposing interlockable rib and groove profiles where one of the profiles has a plurality of indentations spaced longitudinally therealong. These indentations purportedly provide an audible clicking sound or bumpy feel that is perceptible to the user as the cutout or weakened portions flex during closure.  
     SUMMARY OF THE INVENTION  
      The present invention provides a fastening closure strip for use with a reclosable storage container that comprises a pair of interlocking closure elements. The fastening closure strip has a multiple position feature. In accordance with this invention, the user can move the closure strip from one position to another position. The engagement surfaces of the closures are referred to herein as barbed surfaces owing to the multiplicity of their engagement surfaces. One form of such engagement surfaces are often referred to as hooks. Accordingly, references herein to “hooks” are intended to refer to one type of a barb for use in this invention. At least one of the closure elements has a barbed surface to provide the user of the storage container a distinctive tactile “feel” when the container is closed.  
      Structurally, a closure fastening device according to the present invention comprises a pair of opposed, longitudinally extending closure strip elements adapted to interlockingly engage with each other a fully occluded mode. One of the closure element strips includes a plurality of barbs extending from an upright peripheral segment of the closure strip. The second closure element includes a complemental segment that intermittently engages the barbs as the closure elements are moved to the fully occluded mode upon the application of compression forces. This manner of engagement provides a ratcheting sensation to the user of the interlocking closure device.  
      In one embodiment, the first closure element strip comprises a base portion having a pair of spaced-apart, elongate first webs extending therefrom. The webs each include a male hook member extending outwardly from each of the respective webs. The second closure element similarly comprises a pair of webs extending from a second base portion. The second webs include a plurality of spaced-apart female barbs that extend inwardly to permit intermittent ratcheting engagement with the corresponding hook members when the fastening device is moved from a deoccluded mode to the occluded mode.  
      The invention may also be embodied in a closure fastening device comprising a first male closure element that includes a base portion having a pair of spaced-apart, elongate first webs extending therefrom. In this embodiment, the first webs each include a plurality of spaced-apart male barbs extending outwardly from each of the webs. The fastening device includes a female closure element having a pair of second webs extending from a second base portion. At least one of the second webs include a female hook member that extends inwardly to permit intermittent ratcheting engagement with the corresponding male barbs when the fastening device is moved from a deoccluded mode to the occluded mode.  
      In yet another embodiment, a closure fastening device comprises a male closure element with a pair of webs in the form of a serpentine profile configuration to provide a substantial wave like surface. This profile configuration forms a plurality of interleaved protrusions and corresponding depressions. The device further comprises a complementary female closure element including a pair of second webs, each of which has a female hook member adapted to intermittently engage the protrusions of the serpentine profile configuration.  
      Other advantages and embodiments of the invention will be apparent to those skilled in the art upon consideration of the following detailed description and appended claims, and upon reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view of a thermoplastic reclosable container that is suitable for incorporating the present invention.  
       FIG. 2  is a cross sectional view of a fastening device with at least one barbed closure element, taken along the lines  2 - 2  of  FIG. 1 , shown in a non-occluded position according to the present invention.  
       FIG. 3A  is a cross-sectional view of one embodiment of the male closure element according to the invention showing the relative dimensions of the various elements of the male closure element.  
       FIG. 3B  is a cross-sectional view of one embodiment of the female closure element according to the invention suitable for use with the male closure element of  FIG. 3A  and showing the relative dimensions of the various elements of the female closure element.  
       FIG. 4A  and  FIG. 4B  are cross sectional views of the fastening device of  FIG. 2  shown in various positions.  
       FIG. 5A  is a cross sectional view of the fastening device of  FIG. 2  in a fully occluded position.  
       FIG. 5B  is a cross sectional view of another embodiment of the fastening device shown in  FIG. 5A .  
       FIG. 6  is a cross sectional view of a fastening device shown in a non-occluded position according to a second embodiment of the present invention.  
       FIG. 7  and  FIG. 8  are cross sectional views of the fastening device of  FIG. 6  in various positions.  
       FIG. 9A  is a cross sectional view of the fastening device of  FIG. 6  in a fully occluded position.  
       FIG. 9B  is a cross sectional view of another embodiment of the fastening device of  FIG. 9A .  
       FIG. 10  is a cross sectional view of a fastening device shown in a non-occluded position according to a third embodiment of the present invention.  
       FIG. 11  and  FIG. 12  are cross sectional views of the fastening device shown in  FIG. 10  shown in various positions.  
       FIG. 13  is a cross sectional view of the fastening device of  FIG. 10  in a fully occluded position.  
       FIG. 14  is a cross sectional view of a fastening device according to a fourth embodiment of the present invention shown in a partially occluded position.  
       FIG. 15  is a cross sectional view of the fastening device depicted in  FIG. 14  shown in a fully occluded position.  
       FIG. 16  is a cross sectional view of another embodiment of the fastening device of  FIG. 14 .  
       FIG. 17  is a cross sectional view of another embodiment of the present invention.  
       FIG. 18  is a cross sectional view of another embodiment of the present invention.  
       FIG. 19  is a cross sectional view of another embodiment of the present invention.  
       FIG. 20A  is a cross-sectional view of another embodiment shown in a non-occluded position.  
       FIG. 20B  is a cross-sectional view of the fastening device in  FIG. 20A  in the occluded position.  
       FIG. 21  is a cross-sectional view of another embodiment.  
       FIG. 22  is a cross-sectional view of another embodiment.  
       FIG. 23  is a cross-sectional view of another embodiment.  
       FIG. 24  is a cross-sectional view of another embodiment.  
       FIG. 25  is a cross-sectional view of another embodiment.  
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
      Generally, the present invention relates to closure fastening strips that include complemental closure elements arranged to be interlocked over a preselected length of the strip. The fastening closure strip has a multiple position feature. In accordance with this invention, the user can move the closure strip from one position to another position. The engagement surfaces of the closures are referred to herein as barbed surfaces owing to the multiplicity of their engagement surfaces. One form of such engagement surfaces are often referred to as hooks. Accordingly, references herein to “hooks” are intended to refer to one type of a barb for use in this invention. At least one of the closure elements has a barbed surface used to interconnect a complementary closure element surface when the closure elements are placed in an occluded position. The barbed surface provides a feel of ratcheting engagement, as well as an audible sound, to a user of the plastic container upon the application of compressive forces to the closure bases to actively engage the barbs, effectively occluding the fastening strip.  
       FIG. 1  illustrates a thermoplastic container in the form of a plastic reclosable storage bag  4 , that incorporates the teachings of the present invention. The storage bag  4  is formed of a relatively thin plastic film folded along the bottom to provide a pair of opposed sidewalls  6 ,  8  joined together along their side edges, and providing an opening or mouth  9  at the edge opposite the folded edge.  FIG. 1  also shows a closure fastening device  10  including a pair of opposed closure elements  12  and  14  connected to the sidewalls. The closure elements  12 ,  14  preferably each comprise an elongate extruded plastic strip that together form a reclosable fastening device extending longitudinally between the side edges of the opposed sidewalls  6 ,  8 , proximate to the opening of the storage bag  4 .  
       FIG. 2  is a cross sectional view of the closure fastening device  10  illustrating one profile configuration according to the present invention. The device  10  includes a first closure element  12  and a second complementary closure element  14 . In the embodiment shown, the closure elements are each plastic strips that include respective base portions which, in turn, are connected to the container sidewalls. The respective base portions are denoted in  FIG. 1  by numerals  16 ,  18 . Although the closure elements  12 ,  14  are illustrated as separately formed and thereafter connected to a plastic film which forms the sidewalls of the container, they may also be integrally formed with the container sidewalls in a conventional manner.  
      The structural details of the closure elements  12  and  14  are best seen in  FIG. 2 , as well as  FIGS. 3A-4B . The first closure element  12  is a male element comprising a pair of spaced-apart webs  20 ,  22  disposed in parallel relation and extending generally orthogonally to the base portion  16 . As used herein, the term “male” will refer to a closure element or portion that interfits into the mating closure element and has generally outwardly extending hooks or other interlocking portions. The outer element which generally has inwardly extending hooks or other portions will be referred to as a “female” closure element or portion. A pair of male hook members  24 ,  26  are attached to the respective legs such that they face outwardly from each other. In particular, the first male hook member  24  is disposed at the distal end of the first web  20  and protrudes outwardly therefrom. In this embodiment, one of the hook members  24  includes an inwardly extending guide surface  28  that extends at least partially inwardly from the first web  20 . In operation, the guide surface  28  serves to guide the hook members for occlusion with the female barbs of a mating closure element, as described below. As noted above, the second web  22  has the male hook member  26  protruding outwardly from its distal end. This hook member includes a crowned or guide surface  30  that likewise facilitates engagement with the female barbs of the mating closure element. If desired, the guide surface  30  may extend inwardly from the web  22  similar to guide surface  28  and operate in a similar manner. In addition, the webs  20 ,  22  may each include two, three, four or more externally disposed barbs, as may be desired, such as the barbs  26   a - 26   c ,  24   a - 24   c  shown in  FIG. 5B  or the barbs  142   a - c ,  146   a - c  shown in  FIG. 6 .  
      The first closure element  12  also includes a pair of opposed winged guide members  32 ,  34  spaced laterally from the webs  20 ,  22  respectively. Preferably, the guide members  32 ,  34  are each constructed with end segments  32   e ,  34   e  that flare outwardly in order to funnel or guide the complementary webs of the second closure element  14  into alignment with the male hook members  24  and  26  as the closure elements are occluded, as described in greater detail below.  
       FIG. 2  illustrates the structural details of the second female closure element  14 . This closure element similarly comprises first and second spaced-apart webs  36 ,  38  disposed in parallel relation and extending generally orthogonally from the base portion  18 . The first web  36  includes a plurality of spaced-apart integrally formed female barbs  40   a ,  40   b ,  40   c , each of which extends inwardly from the first web  36 . Each of the barbs  40  have generally contoured surfaces  42   a - c  which guide the barbs  40  into mated engagement with the corresponding male hook member  24  of a mating closure element. The barbs further define a plurality of notches  44   a - c  in the interstices between adjacent barbs. Likewise, the second web  38  includes a plurality of spaced-apart female barbs  46   a ,  46   b ,  46   c , which extend inwardly from the second web  38 . These barbs  46  similarly have generally contoured surfaces  48   a - c  which guide the barbs  46  into mated engagement with the corresponding male hook member  26  of a mating closure element. Likewise, the barbs  46  define a plurality of interdigital notches  50   a - c  in the spaces between adjacent barbs. While this particular embodiment shows three barbs per web, each web may have two, three, four, or more barbs as may be desired.  
      In this embodiment, the closure element  14  includes a fin  52  extending from the base  18  between the webs  36 ,  38 . The fin  52  may be included to maintain the structural integrity and facilitate the extrusion of the closure element  18 . Similarly, closure element  12  may also include a fin extending from base  16 . Furthermore, the closure elements  12 ,  14  may include one, two, three or more fins as may be desired. The fin may be used with any of the embodiments in this application as appropriate. In addition, the fin may also be designed to also function as a color enhancement member as described in U.S. Pat. No. 4,829,641, the subject matter of which is incorporated herein by reference.  
      The representative dimensions of a representative male closure element is shown in  FIG. 3A  where the dimensional values corresponding to the letters shown in the drawing are as follows:  
                                       Parameter   Range   Preferred                                            A   0.275-0.355   0.315       B   0.099-0.169   0.134       C   0.026-0.066   0.046       D   0.135-0.215   0.175       F   0.099-0.169   0.134       G   0.013-0.023   0.018                  
 
      The female closure element used in conjunction with the male closure element of  FIG. 3A  is shown in  FIG. 3B  wherein the dimensional parameters are the following for a representative embodiment:  
                                       Parameter   Range   Preferred                  H   0.235-0.315   0.275       I   0.108-0.178   0.143       J   0.013-0.033   0.023       K   0.012-0.022   0.017       L   0.037-0.067   0.052       M   0.023-0.053   0.038       N   0.013-0.023   0.018       O   0.013-0.023   0.018       P   0.013-0.023   0.018       Q   0.024-0.044   0.034                  
 
      In operation, compression forces are applied to the opposed closure elements  12  and  14  in the directions denoted by the arrows  66 ,  68  shown in  FIG. 4A  and  FIG. 4B , substantially normal to the plane of the respective container sidewalls and base portions  16 ,  18 . Such forces are typically applied as the user engages the surfaces of the container and depresses or pinches his or her fingers along a desired length of the closure elements  12 ,  14 . This action moves the opposed male hook members  24 ,  26  into contacting relation with the respective barb elements  40 ,  46  which flexes both pairs of webs to permit clearance of the hook members and barbs, as shown in  FIGS. 4A and 4B . Thus, the respective female webs  36 ,  38  are flexed outwardly. At the same time, the respective webs  20 ,  22  of the male closure element  12  are flexed inwardly.  
      As the closure members are urged together, the male hook members  24 ,  26  intermittently engage corresponding ones of the barbs  40 ,  46  as the hook members are located within the notches disposed intermediate to the barbs. The closure elements thus temporarily achieve the orientation shown in  FIG. 4B . In this way, the closure elements interlock in an interdigitating step-wise fashion until they are fully occluded, as shown in  FIG. 5A . Accordingly, a ratcheting engagement of the male hook members with the barbs that is perceptible to the user occurs as the closure elements are urged together in an interdigitating fashion. In addition, this manner of ratcheting engagement generates an audible sound at each instance in which the hook member disengages from one of the barbs and is located within the notches formed therebetween due to the interdigitating nature of the opposed webs. The sound is caused by the ratcheting or snapping of the hook into the notch which results from the release of the flexure force of the hook. This sound is likewise readily perceptible by the user during a closure operation.  
      Preferably, each such intermittent engagement of the male hook elements with respective ones of the barbs provides sufficient interlocking engagement of the closure elements to maintain closure of the container. In most instances, however, the user will fully occlude the opposed closure members, in part due to the audible sound generated by the fastening device.  
      In order to deocclude the fastening device  10 , the closure elements  12 ,  14  are urged apart from each other by pulling on the mouth portion of the plastic container (see  FIG. 1 ). Such pulling action tends to urge the male webs  20 ,  22  inwardly and the female webs  36 ,  38  outwardly to permit passage of corresponding male hook members  24 ,  26  and barbs  40 ,  46 . The same intermittent engagement is perceived by the user as a ratcheting of the closure elements  12 ,  14 .  
      In  FIGS. 1-5A , the webs  36 ,  38  have a barbed surface and the other webs  20 ,  22  have a complementary surface with a single barb. The ratcheting engagement is achieved when a single barb engages the barbed surface. However, as noted above, the webs  20 ,  22  could include multiple barbs as opposed to a single barb. Thus, a barbed surface would engage another barbed surface as shown in  FIG. 5B .  FIG. 5B  is another embodiment of  FIGS. 1-5A . The webs  20 ,  22  each include three externally disposed hooks  24   a - 24   c ,  26   a - 26   c . Each of these hooks may be of the same size or some of the hooks may be of a different size, such as the smaller hooks  24   c ,  26   c . The number and size of the hooks will depend upon the particular use for the fastening strip.  
       FIG. 6  shows the profile configuration of a fastening device  110  according to a second embodiment of the present invention. In this embodiment, a female closure element  112  includes inwardly oriented hook members which interlock with mating barbs of a male closure element  114 . In particular, the female closure element  112  includes a pair of spaced-apart webs  120 ,  122  disposed in parallel relation and extending generally outwardly from a base portion  116 . In this embodiment, the female webs  120 ,  122  each include a corresponding hook member  124 ,  126  disposed at their respective ends such that they protrude inwardly from each other. Each of the hook members  124 ,  126  are formed with a contoured surface  128 ,  130  to guide the hook members for occlusion with corresponding male barbs of a mating closure element. If desired each female web  120 ,  122  may include two, three or more hook members as shown by hook members  124   a - 124   c ,  126   a - 126   c , in  FIG. 9B .  
      The male closure element  114  comprises a base section  118  that similarly has a pair of spaced-apart webs  136 ,  138  extending outwardly from the base portion  118 . A first one of the webs  136  includes a plurality of spaced-apart barbs  140   a - c , each of which extends outwardly from the first web  136 . As with the female closure element described above, the barbs  140  are formed integrally with the first web  136  and have generally contoured surfaces  142   a - c  which guide the barbs into mated engagement with the corresponding female hook member  124 . The barbs  140  similarly define a plurality of interdigital notches  144   a - c  in the spaces between the barbs. Likewise, the second web  138  includes a plurality of spaced-apart barbs  146   a - c  which extend outwardly from the second web  138 . The barb  146   a  disposed at the distal end of the second web preferably includes an inwardly extending guide surface  148   a  that extends at least partially inwardly from the second web  138 . This guide surface  148   a  assists in guiding the barb  146   a  for occlusion with the mating female hook member. The remaining surfaces corresponding with the barbs  146   b  and  146   c  each include contoured surfaces  148   b - c  to similarly facilitate engagement of the barbs  148   b - c  with the mating female hook member. The barbs  146  additionally form a plurality of interdigital notches  150   a - c  in the spaces between adjacent barbs. As with the embodiment described above, each web may similarly have two, three, four, or more barbs as may be desired.  
      The male closure element  114  also includes a pair of opposed winged guide members  132 ,  134  spaced laterally from the webs  136 ,  138 . As with the guide members described above in connection with  FIGS. 2-5 , the guide members  132 ,  134  are each constructed with end segments  132   e ,  134   e  that flare outwardly away from respective webs  136 ,  136  in order to guide the webs  120 ,  122  of the female closure element into alignment with the male barbs when the closure elements are occluded.  
      In the illustrated embodiment, the female closure element  112  includes a fin  152  extending from the base  116  and the male closure element  114  includes a pair of spaced-apart fins  160 ,  162  extending from the base  118  intermediate the webs  136 ,  138 . The fins  152 ,  160 ,  162  may be included to maintain the structural integrity and facilitate the extrusion of the closure elements  116 ,  118 . The closure elements  112 ,  114  may include one, two, three or more fins as may be desired.  
      The operation of the closure fastening device shown in  FIGS. 6-9B  is similar to that described above. Compression forces similarly are applied to the opposed closure elements  112  and  114  in the direction denoted by the arrows  166 ,  168  in  FIGS. 7 and 8 , substantially normal to the plane of the respective base portions  116 ,  118 . This action moves the opposed female hook members  124 ,  126  into contacting relation with the respective barbs  140 ,  146  which flexes both pairs of webs to permit clearance of the hook members and barbs. This permits intermittent ratcheting engagement of the hook members  124 ,  126  with corresponding ones of the barbs  140 ,  146  as the hook members are located within the interdigital notches  144 ,  150  formed between the barbs. Accordingly, a ratcheting engagement of the female hook members with the barbs that is perceptible to the user occurs as the closure elements are urged together. This ratcheting engagement likewise generates an audible sound at each instance in which the hook member disengages one of the barbs and is located within the notches. As noted above, the same ratcheting feel is perceived by the user when the closure elements  112 ,  114  are deoccluding.  
      Another embodiment of  FIGS. 6-9A  is shown in  FIG. 9B . The webs  120 ,  122  each include three internally disposed hooks  124   a - 124   c ,  126   a - 126   c . Each of these hooks may be of the same size or some of the hooks may be of a different size, such as the smaller hooks  124   c ,  126   c . The number and size of the hooks will depend upon the particular use for the fastening strip.  
       FIG. 10 , as well as  FIGS. 11-13 , illustrate cross sectional profile views of a third embodiment of the present invention. In this embodiment, a first female closure element  212  comprises a pair of spaced-apart webs  220 ,  222  extending outwardly from a base portion  216 . The webs  220 ,  222  each include a hook elements  224 ,  226  disposed at the distal ends of the respective webs that are adapted to interlockingly engage segments of a second male closure element  214 . Each web  220 ,  222  may include one, two, three or more hook members as may be desired. The second closure element  214  includes a pair of spaced-apart serpentine webs  236 ,  238  that extend generally outwardly from a base portion  218 . In this embodiment, the first web  236  of the pair is of a wave like or serpentine configuration, and includes a plurality of spaced protrusions  240   a - c , each of which projects outwardly from the first web  236 . The serpentine profile configuration also defines a plurality of spaced depressions  244   a - c  in the spaces between the protrusions. Likewise, the second web  238  includes spaced protrusions  246   a - c , which extend outwardly from the second web  238 . The profile configuration of the second web  238  similarly defines a plurality of spaced depressions  250   a - c  intermediate to the protrusions. While the webs are shown with three protrusions and corresponding depressions, other numbers of protrusions and depressions may alternatively be utilized, such as, two protrusions and depressions, or four protrusions and depressions, or five or more protrusions and depressions. The protrusions are similar to barbs.  
      The male closure element  214  also includes a pair of guide members  232 ,  234 . As noted above, the guide members  232 ,  234  are spaced laterally from the webs  236 ,  238 , respectively. The first closure element  212  includes a fin  252  extending from the base  216  and the second closure element  214  includes two fins  260 ,  262  extending from the base  218 . The fins  252 ,  260 ,  262  may be included to maintain the structural integrity and facilitate the extrusion of the closure elements. The closure elements  212 ,  214  may include one, two, three or more fins as may be desired.  
      In order to effectuate closure of the fastening device  210  shown in  FIGS. 10-13 , the opposed closure elements  212  and  214  are compressed in a direction substantially normal to the plane of the respective base portions  216 ,  218 . The closure elements are thereby urged into contacting relation as the opposed female hook members  224 ,  226  abut against the ends of the respective serpentine webs  236 ,  238 . This flexes both of the serpentine webs  236 ,  238  inwardly to permit clearance of the hook members and protrusions of the serpentine webs. At the same time, the respective female webs  220 ,  222  are urged outwardly to permit intermittent engagement of the hook members  224 ,  226  within corresponding depressions  244 ,  250  formed in the serpentine webs. This arrangement likewise provides an intermittent, ratcheting engagement of the female hook members  224 ,  226  as they traverse the serpentine webs that is readily perceptible to the user. The user likewise perceives such intermittent engagement when the closure elements are deoccluding. The webs may also have different configurations. For example, both webs could be serpentine and engage in an interdigitating fashion as in  FIGS. 20A and 20B . Similarly, the webs could have a saw tooth configuration as in  FIG. 21 , or a series of rounded protrusions configuration as in  FIG. 22 . The webs could then provide multiple engagements after the first engagement. Several configurations can be utilized as long as the mating and contact points provide a leak resistant closure.  
       FIGS. 14 and 15  illustrate another embodiment of the present invention. In this embodiment, a fastening device  310  includes a plurality of spaced protrusions or bumped surfaces which are formed in the base portion of one of a pair of complementary closure elements. As shown, a first closure element  312  comprises a base portion  316  having a pair of inner male webs  320 ,  322  extending therefrom with male hook portions  324 ,  326  connected to the distal ends of the inner webs. The first hook portion  324  includes a crowned surface  330 , while the second hook portion  326  includes an inwardly facing surface  328 . A pair of outer webs  332 ,  334 , spaced laterally from the inner webs  320 ,  322 , extend from the base portion  316  a distance greater than the inner webs  320 ,  322 . The outer webs  332 ,  334  can be oriented relative to said base in the range of 45-90 degrees with the range of 75-90 degrees preferred. In  FIG. 14 , the outer webs  332 ,  334  are oriented relative to the base  316  at an angle of approximately 82 degrees. The webs  332 ,  334  may have any configuration which will facilitate the movement of the webs  332 ,  334 , such as curved ends  332   a ,  334   a.    
      A second closure element  314  similarly comprises a base portion  318  with a pair of inner female webs  336 ,  338  with female hook portions  340 ,  342  located at the ends of the inner webs. Each of the female hook portions include an inwardly facing surface shown in  FIGS. 14-15  as numerals  344 ,  346 , respectively. As with the embodiments described above, these surfaces facilitate interlocking engagement of the male and female hook portions. The base portion  318  of the female closure element has a substantially greater width than that of the male closure element in order to provide a plurality of protrusions or bumped surfaces  340   a - c ,  346   a - c  extending beyond the outer ends of the male closure element base portion  316 . A plurality of depressions  348   a - c ,  350   a - c  are thus formed intermediate the protrusions. While the illustrated embodiment employs three protrusions and corresponding depressions disposed at the outer ends of the base portion  316 , one, two, three or more protrusions and depressions may also be used as desired.  
      In order to interlock the fastening device, a compression force is applied to the opposed closure elements  312 ,  314  such that the outer webs  332 ,  334  abut corresponding innermost protrusions  340   a ,  346   a , as is shown in  FIG. 14 . As seen in  FIG. 14 , the male and female hook members are not yet in interlocking engagement. Further compression forces flex the outer webs  332 ,  334  such that the ends  332   a ,  334   a  are urged past the protrusions  340   a ,  346   a , respectively, and are next located in the depressions  348   b ,  350   b  formed between the protrusions  340   a - b ,  346   a - b . The outer webs are moved in step-wise fashion until they abut stop surfaces formed on the protrusions  340   c ,  346   c , as shown in  FIG. 15 . In this position, the male and female closure elements are fully occluded. When the closure device is occluded as illustrated in  FIG. 15 , the outer webs  332 ,  334  are oriented relative to the base  316  at an angle of approximately 50 degrees. This arrangement likewise provides a ratcheting engagement of the outer webs with the depressions formed between laterally extending bumped surfaces that is perceptible to the user as the closure elements are urged together. In addition, an audible sound is generated.  
      Another embodiment of the spaced protrusions or bumps is shown in  FIG. 16 . In this embodiment the spaced protrusions have a saw tooth configuration. Specifically, the closure elements  412 ,  414  are similar to the closure elements  312 ,  314  noted above. However, the base portion  418  has a plurality saw tooth protrusions  440   a - 440   c ,  446   a - 446   c . A plurality of depressions  448   a - 448   d ,  450   a - 450   d  are thus formed adjacent the protrusions. The outer webs  432 ,  434  are moved in a step-wise fashion until the webs abut stop surfaces  440   d ,  446   d.    
      The closure device may include other types of closure elements. Referring to  FIG. 17 , the closure device includes a male closure element  512  and a female closure element  514 . The male closure element includes a web  520  which extends from a base  516 . The web  520  includes a head portion  524  and protrusions  527 ,  529 . The female closure element  514  includes a channel  539  and two webs  541 ,  543  which extend from a base  518 . The webs  541 ,  543  include barbs  545   a - 545   c ,  547   a - 547   c  and notches  549   a - 549   c ,  551   a - 551   c  adjacent the barbs. The barbs have generally contoured surfaces which guide the protrusions  527 ,  529  into mated engagement with the notches  549   a - 549   c ,  551   a - 551   c . While this particular embodiment shows three barbs per wall, each wall may have one, two, four or more barbs as may be desired.  
      As the closure elements are urged together, the male protrusions  527 ,  529  intermittently engage corresponding ones of the barbs  545   a - 545   c ,  547   a - 547   c  as the protrusions  527 ,  529  are located within the notches  549   a - 549   c ,  551   a - 551   c . The closure elements interlock in an interdigitating step-wise fashion until they are fully occluded. Accordingly, a ratcheting engagement of the protrusions with the barbs that is perceptible to the user occurs as the closure elements are urged together in an interdigitating fashion. In addition, this manner of ratcheting engagement generates an audible sound at each instance in which the protrusion disengages from one of the barbs and is located within the notches formed therebetween due to the interdigitating nature. The sound is caused by the ratcheting or snapping of the protrusion into the notch which results from the release of the flexure force of the barb. This sound is likewise readily perceptible by the user during a closure operation.  
      Another embodiment of the closure element with multiple barbs is shown in  FIG. 18 . The closure device includes a male closure element  612  and a female closure element  614 . The male closure element  612  includes a web  620  which extends from a base  616 . The web  620  includes a head portion  624 , protrusions  627   a - 627   c ,  629   a - 629   c  and notches  649   a - 649   c ,  651   a - 651   c . The female closure element  614  includes a channel  639  and two webs  641 ,  643  which extend from a base  618 . The webs  641 ,  643  include barbs  645 ,  647 . While this particular embodiment shows three protrusions on each side of the web, each side of the web may have one, two, four or more protrusions as may be desired.  
      As the closure elements are urged together, the male protrusions  627 ,  629  intermittently engage corresponding ones of the barbs  645 ,  647  as the barbs are located within the notches  649   a - 649   c ,  651   a - 551   c . The closure elements interlock in an interdigitating step-wise fashion until they are fully occluded. Accordingly, a ratcheting engagement of the protrusions with the barbs that is perceptible to the user occurs as the closure elements are urged together in an interdigitating fashion. In addition, this manner of ratcheting engagement generates an audible sound at each instance in which the protrusion disengages from one of the barbs and is located within the notches formed therebetween due to the interdigitating nature. The sound is caused by the ratcheting or snapping of the barb into the notch which results from the release of the flexure force of the barb. This sound is likewise readily perceptible by the user during a closure operation.  
      The embodiment shown in  FIG. 19  combines the female closure element of  FIG. 17  with the male closure element in  FIG. 18 . The female closure element  714  is similar to female closure element  514  in  FIG. 17 . The male closure element  712  is similar to male closure element  612  in  FIG. 18 .  
      The female closure element  714  includes a channel  739  and two webs  741 ,  743  which extend from a base  718 . The webs  741 ,  743  include barbs  745 ,  747  and notches  749 ,  751  adjacent the barbs. The barbs have generally contoured surfaces which guide the protrusions  727 ,  729  into mated engagement with the notches  749 ,  751 . While this particular embodiment shows three barbs per wall, each wall may have one, two, four or more barbs as may be desired.  
      The male closure element  712  includes a web  720  which extends from a base  716 . The web  720  includes a head portion  724 , protrusions  727 ,  729  and notches  749 ,  751 . While this particular embodiment shows three protrusions on each side of the web, each side of the web may have one, two, four or more protrusions as may be desired.  
      In order to effectuate closure of the fastening device  710  shown in  FIG. 19 , the opposed closure elements  712  and  714  are compressed in a direction substantially normal to the plane of the respective base portions  716 ,  718 . The closure elements are thereby urged into contacting relation as the web  720  engages the respective webs  741 ,  743 . The webs  741 ,  743  are urged outwardly to permit intermittent engagement of the barbs with the protrusions and intermittent engagement of the barbs and protrusions with the respective notches. This arrangement likewise provides an intermittent, ratcheting engagement that is readily perceptible to the user. The user likewise perceives such intermittent engagement when the closure elements are deoccluding.  
      Referring to  FIGS. 20A and 20B , both webs could be serpentine and engage in an interdigitating fashion. The closure device  810  includes a first closure element  812  and a second closure element  814 .  
      The first closure element  812  is similar to closure element  214  in  FIGS. 10-13 . The first closure element  812  includes a pair of spaced-apart serpentine webs  820 ,  822  that extend generally outwardly from a base portion  816 . In this embodiment, the first web  820  of the pair is of a wave like or serpentine configuration, and includes a plurality of spaced protrusions  824   a - c , each of which projects outwardly from the first web  820 . The serpentine profile configuration also defines a plurality of spaced depressions  825   a - c  in the spaces between the protrusions. Likewise, the second web  822  includes spaced protrusions  826   a - c , which extend outwardly from the second web  822 . The profile configuration of the second web  822  similarly defines a plurality of spaced depressions  827   a - c  intermediate to the protrusions. While the webs are shown with three protrusions and corresponding depressions, other numbers of protrusions and depressions may alternatively be utilized, such as, two protrusions and depressions, or four protrusions and depressions, or five or more protrusions and depressions. The protrusions are similar to barbs.  
      The second closure element  814  is similar to the first closure element  812 . The second closure element  814  includes a pair of spaced-apart serpentine webs  836 ,  838  that extend generally outwardly from a base portion  818 . In this embodiment, the first web  836  of the pair is of a wave like or serpentine configuration, and includes a plurality of spaced protrusions  840   a - c , each of which projects outwardly from the first web  836 . The serpentine profile configuration also defines a plurality of spaced depressions  844   a - c  in the spaces between the protrusions. Likewise, the second web  838  includes spaced protrusions  846   a - c , which extend outwardly from the second web  838 . The profile configuration of the second web  838  similarly defines a plurality of spaced depressions  850   a - c  intermediate to the protrusions. While the webs are shown with three protrusions and corresponding depressions, other numbers of protrusions and depressions may alternatively be utilized, such as, two protrusions and depressions, or four protrusions and depressions, or five or more protrusions and depressions. The protrusions are similar to barbs.  
      The male closure element  814  also includes a pair of guide members  832 ,  834 . As noted above, the guide members  832 ,  834  are spaced laterally from the webs  836 ,  838 , respectively. The first closure element  812  includes a fin  852  extending from the base  816  and the second closure element  814  includes two fins  860 ,  862  extending from the base  818 . The fins  852 ,  860 ,  862  may be included to maintain the structural integrity and facilitate the extrusion of the closure elements. The closure elements  812 ,  814  may include one, two, three or more fins as may be desired.  
      In order to effectuate closure of the fastening device  810  shown in  FIG. 20A , the opposed closure elements  812  and  814  are compressed in a direction substantially normal to the plane of the respective base portions  816 ,  818 . The closure elements are thereby urged into contacting relation as the opposed serpentine webs  820 ,  822  abut against the respective serpentine webs  836 ,  838 . The serpentine webs  836 ,  838  flex inwardly to permit intermittent engagement of the protrusions with the other protrusions and intermittent engagement of the protrusions with the depressions. At the same time, the respective webs  820 ,  822  are urged outwardly to permit intermittent engagement of the protrusions with the other protrusions and intermittent engagement of the protrusions with the depressions. This arrangement likewise provides an intermittent, ratcheting engagement that is readily perceptible to the user. The user likewise perceives such intermittent engagement when the closure elements are deoccluding.  
      Referring to  FIG. 21 , both webs could have a saw tooth configuration and engage in an interdigitating fashion. The closure device  910  includes a first closure element  912  and a second closure element  914 .  
      The first closure element  912  includes a pair of spaced-apart webs  920 ,  922  that extend generally outwardly from a base portion  916 . In this embodiment, the first web  920  of the pair includes a plurality of spaced triangular protrusions  924 , each of which projects outwardly from the first web  920 . The profile configuration also defines a plurality of spaced depressions  925  in the spaces between the protrusions. Likewise, the second web  922  includes spaced triangular protrusions  926 , which extend outwardly from the second web  922 . The profile configuration of the second web  922  similarly defines a plurality of spaced depressions  927  intermediate to the protrusions. While the webs are shown with four protrusions and corresponding depressions, other numbers of protrusions and depressions may alternatively be utilized, such as, two protrusions and depressions, or three protrusions and depressions, or five or more protrusions and depressions. The protrusions are similar to barbs.  
      The second closure element  914  is similar to the first closure element  912 . The second closure element  914  includes a pair of spaced-apart webs  936 ,  938  that extend generally outwardly from a base portion  918 . In this embodiment, the first web  936  of the pair includes a plurality of spaced triangular protrusions  940 , each of which projects outwardly from the first web  936 . The profile configuration also defines a plurality of spaced depressions  944  in the spaces between the protrusions. Likewise, the second web  938  includes spaced triangular protrusions  946 , which extend outwardly from the second web  938 . The profile configuration of the second web  938  similarly defines a plurality of spaced depressions  950  intermediate to the protrusions. While the webs are shown with four protrusions and corresponding depressions, other numbers of protrusions and depressions may alternatively be utilized, such as, two protrusions and depressions, or three protrusions and depressions, or five or more protrusions and depressions. The protrusions are similar to barbs.  
      The male closure element  914  also includes a pair of guide members  932 ,  934 . As noted above, the guide members  932 ,  934  are spaced laterally from the webs  936 ,  938 , respectively. The first closure element  912  includes a fin  952  extending from the base  916  and the second closure element  914  includes two fins  960 ,  962  extending from the base  918 . The fins  952 ,  960 ,  962  may be included to maintain the structural integrity and facilitate the extrusion of the closure elements. The closure elements  912 ,  914  may include one, two, three or more fins as may be desired.  
      In order to effectuate closure of the fastening device  910  shown in  FIG. 21 , the opposed closure elements  912 ,  914  are compressed in a direction substantially normal to the plane of the respective base portions  916 ,  918 . The closure elements are thereby urged into contacting relation as the opposed webs  920 ,  922  abut against the respective webs  936 ,  938 . The webs  936 ,  938  flex inwardly to permit intermittent engagement of the protrusions with the other protrusions and intermittent engagement of the protrusions with the depressions. At the same time, the respective webs  920 ,  922  are urged outwardly to permit intermittent engagement of the protrusions with the other protrusions and intermittent engagement of the protrusions with the depressions. This arrangement likewise provides an intermittent, ratcheting engagement that is readily perceptible to the user. The user likewise perceives such intermittent engagement when the closure elements are deoccluding.  
      The triangular protrusions  924 ,  926 ,  940 ,  946  are designed so that the force required to occlude the closure device is less than the force required to deocclude the closure device. Specifically, the faces of the triangular protrusions which contact during occlusion are at an angle which will facilitate occlusion. The faces of the triangular protrusions which contact during deocclusion are horizontal which will make deocclusion more difficult than occlusion. The angles of the faces can be changed to achieve the desired results.  
      Referring to  FIG. 22 , both webs could have a rounded protrusions configuration and engage in an interdigitating fashion. The closure device  1010  includes a first closure element  1012  and a second closure element  1014 .  
      The first closure element  1012  includes a pair of spaced-apart webs  1020 ,  1022  that extend generally outwardly from a base portion  1016 . In this embodiment, the first web  1020  of the pair includes a plurality of spaced rounded protrusions  1024 , each of which projects outwardly from the first web  1020 . The profile configuration also defines a plurality of spaced depressions  1025  in the spaces between the protrusions. Likewise, the second web  1022  includes spaced rounded protrusions  1026 , which extend outwardly from the second web  1022 . The profile configuration of the second web  1022  similarly defines a plurality of spaced depressions  1027  intermediate to the protrusions. While the webs are shown with three protrusions and corresponding depressions, other numbers of protrusions and depressions may alternatively be utilized, such as, two protrusions and depressions, or four protrusions and depressions, or five or more protrusions and depressions. The protrusions are similar to barbs.  
      The second closure element  1014  is similar to the first closure element  1012 . The second closure element  1014  includes a pair of spaced-apart webs  1036 ,  1038  that extend generally outwardly from a base portion  1018 . In this embodiment, the first web  1036  of the pair includes a plurality of spaced rounded protrusions  1040 , each of which projects outwardly from the first web  1036 . The profile configuration also defines a plurality of spaced depressions  1044  in the spaces between the protrusions. Likewise, the second web  1038  includes spaced rounded protrusions  1046 , which extend outwardly from the second web  1038 . The profile configuration of the second web  1038  similarly defines a plurality of spaced depressions  1050  intermediate to the protrusions. While the webs are shown with three protrusions and corresponding depressions, other numbers of protrusions and depressions may alternatively be utilized, such as, two protrusions and depressions, or four protrusions and depressions, or five or more protrusions and depressions. The protrusions are similar to barbs.  
      The second closure element  1014  also includes a pair of guide members  1032 ,  1034 . As noted above, the guide members  1032 ,  1034  are spaced laterally from the webs  1036 ,  1038 , respectively. The first closure element  1012  includes a fin  1052  extending from the base  1016  and the second closure element  1014  includes two fins  1060 ,  1062  extending from the base  1018 . The fins  1052 ,  1060 ,  1062  may be included to maintain the structural integrity and facilitate the extrusion of the closure elements. The closure elements  1012 ,  1014  may include one, two, three or more fins as may be desired.  
      In order to effectuate closure of the fastening device  1010  shown in  FIG. 22 , the opposed closure elements  1012  and  1014  are compressed in a direction substantially normal to the plane of the respective base portions  1016 ,  1018 . The closure elements are thereby urged into contacting relation as the opposed webs  1020 ,  1022  abut against the respective webs  1036 ,  1038 . The webs  1036 ,  1038  flex inwardly to permit intermittent engagement of the protrusions with the other protrusions and intermittent engagement of the protrusions with the depressions. At the same time, the respective webs  1020 ,  1022  are urged outwardly to permit intermittent engagement of the protrusions with the other protrusions and intermittent engagement of the protrusions with the depressions. This arrangement likewise provides an intermittent, ratcheting engagement that is readily perceptible to the user. The user likewise perceives such intermittent engagement when the closure elements are deoccluding.  
       FIG. 23  illustrates another embodiment of the present invention. In this embodiment, a fastening device  1110  includes outer webs with a barbed surface which are disposed at an angle to the base portion. The fastening device  1110  includes a first closure element  1112  and a second closure element  1114 . The first closure element  1112  includes inner webs  1120 ,  1122  and a base  1116  which are similar to webs  120 ,  122  and base  116  in  FIG. 6 . The first closure element  1112  also includes outer webs  1132 ,  1134  which are disposed at an angle to the base portion  1116 . The outer webs  1132 ,  1134  can be oriented relative to said base in the range of 30-60 degrees with the angle of 45 degrees preferred. In  FIG. 23 , the outer webs  1132 ,  1134  are oriented relative to the base at an angle of approximately 45 degrees. The outer webs  1132 ,  1134  include barbed surfaces  1140 ,  1146 . While this embodiment employs surfaces  1140 ,  1146 , other embodiments may use other surfaces, such as surfaces  340 ,  346  in  FIGS. 14-15  or surfaces  440 ,  446  in  FIG. 16 .  
      The second closure element  1114  includes inner webs  1121 ,  1123  and a base  1117  which are similar to webs  20 ,  22  and base  16  in  FIG. 2 . The second closure element  1114  also includes outer webs  1133 ,  1135  which are disposed at an angle to the base portion  1117 . The outer webs  1133 ,  1135  can be oriented relative to said base in the range of 30-60 degrees with the angle of 45 degrees preferred. In  FIG. 23 , the outer webs  1133 ,  1135  are oriented relative to the base at an angle of approximately 45 degrees. The outer webs  1133 ,  1135  include barbed surfaces  1141 ,  1145 . The barbed surface may have any configuration which will appropriately engage the corresponding web.  
      In this embodiment, the barbed surface includes triangular protrusions. The triangular protrusions are designed to control the magnitude of the tactile sensation both during opening and closing of the closure device. Specifically, the faces of the triangular protrusions which contact during occlusion are at an angle which will create a strong tactile sensation during occlusion. The faces of the triangular protrusions which contact during deocclusion are substantially vertical which will create a reduced or mild tactile sensation during occlusion. The angle of the faces can be changed to achieve the desired results.  
      The fastening device  1110  is shown in the occluded position in  FIG. 23 . Compression forces are applied to the closure elements  1112 ,  1114  and the webs are urged into contact with each other. The inner webs engage as noted above with respect to  FIGS. 14-16 . The outer webs flex as the barbed surface of one web  1134 ,  1135  engage the barbed surface of the other web  1132 ,  1133 . This action permits intermittent ratcheting engagement in an interdigitating fashion. Accordingly, a ratcheting engagement is perceptible to the user as the closure elements are urged together in an interdigitating fashion. In addition, this manner of ratcheting engagement may generate an audible sound perceptible to the user during the closure operation. The ratcheting feel may be perceived by the user when the closure elements are deoccluding.  
       FIG. 24  illustrates another embodiment of the present invention. In this embodiment, the fastening device includes inner webs with barbed surfaces and outer webs with barbed surfaces. The fastening device  1210  includes a first closure element  1212  and a second closure element  1214 . The first closure element  1212  includes inner webs  1220 ,  1222  and a base  1216  which are similar to webs  120 ,  122  and base  116  in  FIG. 9B . While this embodiment employs webs  1220 ,  1222 , other embodiments may use other webs, such as, the webs in  FIGS. 2-9A ,  10 - 13 , and  17 - 22 . The first closure element  1212  also includes outer webs  1232 ,  1234  which are similar to webs  1132 ,  1134  in  FIG. 23 .  
      The second closure element  1214  includes inner webs  1236 ,  1238  and a base  1218  which are similar to webs  136 ,  138  and base  118  in  FIG. 9B . While this embodiment employs webs  1220 ,  1222 , other embodiments may use other webs, such as, the webs in  FIGS. 2-9A ,  10 - 13 , and  17 - 22 . The second closure element  1214  also includes outer webs  1233 ,  1235  which are similar to webs  1133 ,  1135  in  FIG. 23 .  
      The fastening device  1210  is shown in the occluded position in  FIG. 24 . Compression forces are applied to the closure elements  1212 ,  1214  and the webs are urged into contact with each other. The inner webs engage as noted above with respect to  FIGS. 6-9A  and especially  FIG. 9B . The outer webs engage as noted above for  FIG. 23 . The ratcheting engagement of the inner webs and outer webs is perceptible to the user as the closure elements are urged together in an interdigitating fashion. In addition, this manner of ratcheting engagement may generate an audible sound perceptible to the user during a closure operation. The ratcheting feel may be perceived by the user when the closure elements are deoccluding.  
       FIG. 25  illustrates another embodiment of the invention. In this embodiment, the fastening device includes inner webs with barbed surfaces and a barbed surface on the base portion of one of the closure elements. The fastening device  1310  includes a first closure element  1312  and a second closure element  1314 . The first closure element  1312  includes inner webs  1320 ,  1322  and a base  1316  which are similar to webs  1220 ,  1222  and base  1216  in  FIG. 24 . While this embodiment employs webs  1320 ,  1322 , other embodiments may use other webs, such as, the webs in  FIGS. 2-13  and  17 - 22 . The first closure element  1212  includes a barbed surface  1340 ,  1346  on the base which are similar to surfaces  440 ,  446  in  FIG. 16 . While this embodiment employs barbed surfaces  1340 ,  1346 , other embodiments may use other surfaces, such as, surfaces  340 ,  346  in  FIGS. 14 and 15 .  
      The second closure element  1314  includes inner webs  1336 ,  1338  and a base  1318  which are similar to webs  1236 ,  1238  and base  1218  in  FIG. 24 . While this embodiment employs webs  1336 ,  1338 , other embodiments may use other webs, such as, the webs in  FIGS. 2-13  and  17 - 22 . The second closure element  1314  also includes outer webs  1332 ,  1334  which are similar to webs  432 ,  434  in  FIG. 16 .  
      The fastening device  1010  is shown in the occluded position in  FIG. 25 . Compression forces are applied to the closure elements  1312 ,  1314  and the webs are urged into contact with each other. The inner webs engaged as noted above with respect to  FIG. 24 . The outer webs engage as noted above for  FIG. 16 . The ratcheting engagement of the inner webs and the outer webs is perceptible to the user as the closure elements are urged together in an interdigitating fashion. In addition, this manner of ratcheting engagement may generate an audible sound perceptible to the user during a closure operation. The ratcheting feel may be perceived by the user when the closure elements are deoccluding.  
      The closure fastening devices of this invention are preferably formed from thermoplastic materials such as high, medium or low density polyethylene or from other resins. Such fastening devices can readily be manufactured by known methods such as by extrusion, by the use of molds or other known methods of producing such devices. They can be manufactured as a strip for later attachment to a plastic film or they can be formed integral with the film. In the instance where formed by extrusion, the closure fastening devices may be extruded with or without flange portions on one or both of the closure elements depending on the particular manufacturing operations utilized.  
      There are various advantages to the fastening device according to the present invention. For example, the barbed arrangement provides an enhanced feel to the user. Furthermore, the present invention provides an enhanced feel with an arrangement that provides various points of occlusion. In addition, the invention, when utilized in an arrangement comprising multiple barbs, may provide step-wise color enhancement to provide various degrees of visual indication. In particular, the user may perceive different shades of color change depending on the level of occlusion of the barbs with corresponding hooks when looking at the fastening device from the side.  
      Accordingly, a closure fastening device that includes a first closure element with at least one barbed surface and a second closure element with a complementary mating surface that provides intermittent ratcheting engagement with the barbed surface that meets the aforestated objectives has been described. In this way, the user perceives a tactile feel as the closure elements are engaged. It will be apparent to those skilled in the art that a number of modifications can be made to the invention disclosed, particularly by those having the benefit of the foregoing teachings, without departing from the spirit of these principles. Accordingly, it is intended that the invention be limited only by the scope of the appended claims.