Abstract:
A clasp for holding two ends of cords or the like together includes a shaft member insertable into and engageable with a latch member. The latch member is a round tube having an open front end through which the shaft member may be inserted and withdrawn. Attached to the latch member is a spring member with a hook (tab) extending from a free end thereof through a hole in the side of the latch member. The shaft has a notch. The clasp is engaged by aligning the tab of the latch member with the notch of the shaft member and pushing the shaft member into the open end of the latch member until the tab engages the notch. The clasp is disengaged by rotating the shaft member relative to the latch member so that the tab is urged out of the notch, then pulling the shaft member out of the latch member.

Description:
TECHNICAL FIELD OF THE INVENTION  
         [0001]    The invention is directed to clasps for jewelry and the like and, more particularly, to clasps of the type having an inner member which is inserted into and releasably retained within an outer member.  
         BACKGROUND OF THE INVENTION  
         [0002]    Clasps are used for connecting the terminal ends of one or more flexible members to one another, such as necklaces, bracelets, watch bands, cords and the like. Clasps are also known for connecting an object, such as a fish hook to a line.  
           [0003]    A type of clasp is known wherein an inner shaft member is formed having a tongue or hook disposed to engage a recess or opening in an outer latch member. These type clasps share a disadvantage in that it is relatively easy to depress the tongue, and thereby permit the shaft member to disengage from the latch member. Solutions to this problem have tended to create clasps which are complex, expensive to manufacture and difficult to use.  
           [0004]    Other types of clasps have a U-shaped member that another member slips over to hold the open end of the U together. If these fasteners are required to be small, they are difficult to use.  
           [0005]    Thus, there remains a continuing need for a clasp that can be made small yet is still easy for the user to use (engage and disengage), relatively inexpensive to manufacture, and less likely to disengage while in use.  
           [0006]    Examples of clasps are disclosed in the following documents: U.S. Pat. Nos. 4,024,607; 4,246,679; 4,364,155; 4,426,854; 4,566,159; 4,571,788; 4,958,420; 5,457,860; 5,628,095; 6,058,576; and 6,088,884.  
         SUMMARY OF THE INVENTION  
         [0007]    An object of the present invention is to provide a clasp that can be made small and substantially reduce the likelihood of unwanted disengagement.  
           [0008]    Another object of this invention is to provide a clasp which can have varying amounts of holding power with a relatively minor design change.  
           [0009]    Another object of this invention is to provide a clasp which is relatively simple in construction, easy and economical to manufacture and easy to use even with gloved hands.  
           [0010]    This invention is a clasp for releasably holding two cord ends or the like together such as two ends of a necklace, or such as a fish hook to a line.  
           [0011]    According to the invention, a shaft member is insertable into and engageable with a latch member. The latch member is in the form of a round tube (cylinder) with a hole in the side and an open front end through which the shaft member may be inserted and withdrawn. Attached to the exterior of the latch member is a spring member with a hook portion (“tab”) which extends through the hole to the interior of the latch member. The hole in the side of the latch member need only be large enough to permit the tab to go through, and it is disposed near the insertion (front) end of the latch member. The other (rear) end of the latch member is open, and has a ring to which one cord or one end of a necklace may be attached. Alternatively, the rear end of the latch member can be closed. Alternatively, the spring member can be formed integrally with the latch member.  
           [0012]    The shaft member can be as simple as a rod with a notch in the side. The shaft member also has an eyelet to which a cord or other end of a necklace is attached.  
           [0013]    The clasp is engaged by aligning the tab of the latch member with the notch of the shaft member and pushing the shaft member into the open end of the latch member such that the tab is engaged with the notch.  
           [0014]    The clasp is disengaged by rotating the shaft member relative to the latch member so that the tab is pushed (urged) out of the notch, then, pulling the shaft member out of the latch member.  
           [0015]    Other objects, features and advantages of the invention will become apparent in light of the following description thereof. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    Reference will be made in detail to preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. The drawings are intended to be illustrative, not limiting. Certain elements selected drawings may be illustrated not-to-scale, for illustrative clarity.  
         [0017]    Often, similar elements throughout the drawings may be referred to by similar reference numerals. For example, the element  199  in a figure (or embodiment) may be similar in many respects to the element  299  in another figure (or embodiment). Such a relationship, if any, between similar elements in different figures or embodiments will become apparent throughout the specification, including, if applicable, in the claims and abstract. In some cases, similar elements may be referred to with similar numbers in a single drawing. For example, a plurality of elements  199  may be referred to as  199   a ,  199   b ,  199   c , etc.  
         [0018]    The structure, operation, and advantages of the present preferred embodiment of the invention will become further apparent upon consideration of the following description taken in conjunction with the accompanying figures, wherein:  
         [0019]    [0019]FIG. 1 is a side, cross-sectional view of an embodiment of a clasp, according to the invention;  
         [0020]    [0020]FIGS. 1A and 1B are end cross-sectional views of the shaft member of the clasp of FIG. 1, taken along lines a-a and b-b through the shaft member, respectively, according to the invention;  
         [0021]    [0021]FIG. 1C is an end cross-sectional view of the latch member of the clasp of FIG. 1, taken on a line c-c through the latch member, according to the invention;  
         [0022]    [0022]FIG. 2 is a side, cross-sectional view of the clasp of FIG. 1, showing the shaft member partially inserted into the latch member, according to the invention;  
         [0023]    [0023]FIG. 3 is a side, cross-sectional view of the clasp of FIG. 1, showing the shaft member fully inserted into the latch member, according to the invention;  
         [0024]    [0024]FIG. 4A is an end cross-sectional view, taken on a line d-d through FIG. 2, according to the invention;  
         [0025]    [0025]FIG. 4B is an end cross-sectional view, taken on a line e-e through FIG. 3, according to the invention;  
         [0026]    [0026]FIG. 4C is an end cross-sectional view, comparable to the view of FIG. 4B, with the shaft member rotated, according to the invention;  
         [0027]    [0027]FIG. 5 is a partial side, cross-sectional view of an alternate embodiment of a clasp, according to the invention;  
         [0028]    [0028]FIG. 6 is a partial side, cross-sectional view of an alternate embodiment of a clasp, according to the invention;  
         [0029]    [0029]FIG. 7 is a partial end, cross-sectional view of an alternate embodiment of a clasp, according to the invention; and  
         [0030]    [0030]FIG. 8 is a side, cross-sectional view of an alternate embodiment of a latch member for a clasp, according to the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0031]    The invention is a clasp for connecting the terminal ends of a flexible, typically elongate element (or elements), such as articles of jewelry, such as necklaces, bracelets, watch bands and the like. The invention is also applicable to connecting two dissimilar elements with one another for example, a fish hook to a fishing line.  
         [0032]    An Embodiment of the Clasp  
         [0033]    [0033]FIGS. 1, 1A,  1 B,  1 C,  2 ,  3 ,  4 A,  4 B and  4 C illustrate a first embodiment of the clasp  100  of the present invention, the major components of which are:  
         [0034]    a latch member  110 ;  
         [0035]    a shaft member  130 ; and  
         [0036]    a spring member  150 .  
         [0037]    The latch member  110  is elongate and is generally cylindrical (tubular), having a front end  112 , a rear end  114  which is opposite the front end  112 , an inside surface  116 , and an outside surface  118 . The latch member  110  is open at the front end  112 , and is preferably open at the rear end  114 . The latch member  110  has an inside diameter D 1 . The inside surface  116  is preferably of uniform diameter, rather than tapered. The outside surface  118  is shown as being of uniform diameter, but it need not be. The latch member  110  has a cylindrical wall  120 . A hole (opening)  122  extends through the wall  120 , from the outside surface  118  to the inside surface  116  thereof, at an intermediate position along the length of the latch member  110 , such as approximately 25-50% of the distance from the front end  112  to the rear end  114 . This hole  122  is for receiving a hook portion (“tab”)  154  of a spring member  150 , described in greater detail hereinbelow. Another hole (opening)  124  extends through the wall  120  of the latch member  110 , from the outside surface  118  to the inside surface  116  thereof, at a location closely adjacent the rear end  114  (e.g., within 10% of the length of the latch member  110 ), for receiving a ring  126  which is described in greater detail hereinbelow. The latch member  110  is suitably constructed as a thin-walled, strong, round tube, such as of metal (e.g., tin, steel, silver, gold, and alloys thereof).  
         [0038]    The shaft member  130  is elongate and is generally cylindrical (tubular), having a front end  132 , a rear end  134  which is opposite the front end  132 , and an outside surface (external)  136 . The shaft member  110  has an outside diameter D 2 , which is slightly (e.g., for a jewelry clasp, a few thousandths of an inch) less than the inside diameter D 1  of the latch member  110 . This is so the shaft member  130  can be inserted into the latch member  110 . (The open rear end  114  of the latch member  110  allows for debris to be ejected from the latch member  110  when the shaft member  130  is inserted therein.) The shaft member  130  is suitably constructed of a solid, hard, round rod, such as of metal. (The rear end  134  of the shaft member  130  is shown simplified, in FIG. 1, for illustrative clarity.)  
         [0039]    The front end  132  of the shaft member  130  is rounded. At an intermediate position along its length, such as approximately halfway between the front end  132  and the rear end  134 , a notch (groove)  140  is provided which extends radially into the shaft member  130  a distance d 2 . The distance d 2  is suitably a fraction, such as approximately one-third to one-half of the shaft diameter D 2 . The notch  140  has a longitudinal extent which corresponds to a thickness of a tab ( 154 ) of a spring member ( 150 ), which is described in greater detail hereinbelow. The notch  140  extends circumferentially, approximately 180-degrees (i.e., halfway) around the shaft member  130 , has a front wall  142 , a back wall  144 , and a ramp (cam) surface  146 .  
         [0040]    [0040]FIGS. 1A and 1B are cross-sections of the shaft member  130 , taken at various positions along its length—namely, referring to FIG. 1, at a position (a-a) forward of the notch  140 , and at the location (b-b) through the notch  140 , respectively. The front end  132  of the shaft member  130  is rounded. Rearward of the notch  140 , the shaft member  130  is suitably substantially cylindrical. The overall diameter of the shaft member  130  diminishes from the notch  140  to the front end thereof. The shaft member  130  is tapered, from the front end  132  towards the rear end  134  so that it can easily be inserted into the latch member  110 , as discussed hereinbelow.  
         [0041]    The spring member  150  is elongate and is made of a resilient material, such as spring steel. It has two major portions: an elongate body portion  152  having two ends (not numbered in the figures)—a one end which is affixed to the latch member and an opposite end which is a free end. The spring member  150  has a tab (pawl, tooth) portion  154  extending from the free end (the free end) of the body portion  152 . The tab  154  is preferably contiguous, and integrally formed with the body portion  152 . The spring member  150  is secured (affixed) to the external surface  118  of the latch member  110  in any suitably manner, such as with a rivet  156  (alternatively, with a bolt, a screw, a tab, welded, soldered, glue, or the like).  
         [0042]    The tab  154  extends at a right angle from the free end of the body portion  152 , through the hole  122 , into the interior (bore) of the latch member  110 , a distance d 1 , which is preferably less than half, preferably one-quarter of, the inside diameter D 1  of the latch member  110 , and which is slightly less than the depth d 2  of the notch  140 . Stated in other terms, the depth d 2  of the notch  140  is slightly greater than the length d 1  of the tab  154 . Since the body portion  152  is a resilient material, the tab  154  can deflect resiliently, radially out of the hole  122  in the latch member  110  when the shaft member  130  is inserted therein, as discussed hereinbelow. The tab  154  itself need not be resilient and, although shown as being integral with the body portion  152 , it can be a separate element which is assembled to the end of the body portion  152 . The tab  154  has a width (best viewed in FIG. 1C), which is approximately one-quarter (shown not-to-scale, for illustrative clarity) of the inside diameter D 1  of the latch member  110 . FIG. 1C is a cross-sectional view taken on a line c-c through the latch member  110  of FIG. 1, and shows the tab  154  of the spring member  150  extending through the wall  120 , into the bore (interior) of the latch member  110 .  
         [0043]    [0043]FIG. 2 illustrates the clasp  100 , with the shaft member  130  partially inserted into the latch member  110 . A ring  126  is disposed through the hole  124 , and is for attaching to an end  103  of an elongate element  102 , such as a jewelry chain. (The ring  126  and elongate element  102  are omitted from FIGS. 1 and 3, for illustrative clarity.) In this view, it is shown that the rear end  134  of the shaft member  130  may be formed with an area of reduced diameter having a hole (eyelet)  146  therethrough for receiving a ring  127  which is for attaching to an end  105  of an elongate element  104 , such as a jewelry chain. (The ring  127  and elongate element  104  are omitted from FIGS. 1 and 3, for illustrative clarity.) The two ends  103  and  105  of elongate elements  102  and  104 , respectively, can be two opposite ends of a single element, such as a jewelry chain.  
         [0044]    [0044]FIG. 3 illustrates the clasp  100 , with the shaft member  130  fully inserted into the latch member  110 .  
         [0045]    Use of the Clasp  
         [0046]    The sequence of operations to engage the clasp  100  is to first align the notch  140  with the tab  154 , both of which are shown as being in the “12 O&#39;clock” position in FIGS. 1, 1A,  1 B,  1 C,  2  and  3 . Then, the user inserts the front end  132  of the shaft member  130  into the front end  112  of the latch member  110 . This causes the tab  154  of the spring member  150  to deflect resiliently upwards. FIGS. 2 and 4A illustrate the shaft member  130  partially inserted into the latch member  110 , and the tab  154  having been resiliently deflected upwards, so that it is out of the bore of the latch member. The user continues to insert the shaft member  130  into the latch member  110 , and when the notch  140  aligns under the tab  154 , the tab  154  will enter the notch  140 , thereby resisting (substantially preventing) further insertion of the shaft member  130  into the latch member  110  or removal of the shaft member  130  from the latch member  110 . FIGS. 3 and 4B illustrate the shaft member  130  fully inserted into the latch member  110 , and the tab  154  disposed within the notch  140 .  
         [0047]    The sequence of operations to disengage the clasp is illustrated primarily by FIG. 4C. First, the user rotates the shaft member  130 , for example to the “7 O&#39;clock” position. This will cause the tab  154  to “ride up” along the ramp (cam) surface  146  of the notch  140  until it is at the external surface  136  of the shaft member  130  (i.e., until it is no longer in the notch  140 ). (Rotating the shaft member  130  urges the tab  154  out of the notch  140 .) The shaft member  130  can then simply be withdrawn from the latch member  110  (in the reverse direction from engagement). In other words, rotation of the shaft member  130  forces the tab  154  of the spring member  150  out of the bore of the latch member  110 .  
         [0048]    An advantage of the present invention is that the clasp is relatively immune from accidental disengagement. It is difficult to cause the tab to exit the notch other than by rotating the shaft element, and the force of the tab against the ramped surface is sufficient to require advertent action to be taken to disengage the clasp. The disengagement force flexes the spring element, and is directed opposite to the tension expected in normal use. Catching the spring element and exerting a force to flex the spring element is very difficult to accomplish, other than by rotating the shaft element. A force in any other direction will not disengage the shaft member. Even pushing directly on the tab will not disengage the clasp. A rotation pressure such as used in disengagement of insufficient strength will not disengage the clasp.  
         [0049]    Alternate Embodiments  
         [0050]    The resilient force with which the tab  154  is maintained within the bore of the latch member  110  can be designed by changing the dimensions (e.g., length) or the material (namely, with regard to spring constant) of the spring member  150 , or by changing the location of the rivet  156 . Also, by modifying the radial extent of the tab  154  and, as described hereinbelow, its angle, the force necessary to disengage the shaft member  130  from the latch member  110  can be altered.  
         [0051]    The shaft member  130  should have an overall length which is sufficient (long enough) to allow the tab  154  to enter the notch  140 , but which is short enough to keep the overall clasp  100  of small size for jewelry items. It is within the scope of the invention that multiple notches can be provided in the shaft member to permit engagement of the tab  154  at different engagement distances, to permit adjusting the overall, ends-connected length of a cord  102  or the like. It is also within the scope of the invention that multiple tabs can be provided along the length of the spring element, extending though corresponding multiple holes in the latch member, to engage corresponding multiple notches on the shaft member, to increase the holding power of the clasp.  
         [0052]    The angle between the tab  154  and the body portion  152  of the spring member  150  is illustrated in FIGS. 1, 2 and  3  as being approximately 90 degrees (i.e., a “right” angle). In the alternate embodiments described hereinbelow, the angle is described as being less than or greater than 90 degrees.  
         [0053]    [0053]FIG. 5 illustrates a portion of an alternate embodiment of a clasp, wherein the tab  154 ′ extends at an acute angle (less than 90 degrees), such as approximately 80 degrees, from the body portion  152 ′ of the spring element  150 ′. The notch  140 ′ in the shaft element  130 ′ is shaped accordingly so that the tab  154 ′ can enter the notch  140 ′. This is one way of providing for better holding power and greater strength (“strong hold”).  
         [0054]    [0054]FIG. 6 illustrates portion of an alternate embodiment of a clasp, wherein the tab  154 ″ extends at an obtuse angle (greater than 90 degrees), such as approximately 100 degrees, from the body portion  152 ″ of the spring element  150 ″. The notch  140 ″ in the shaft element  130 ″ is shaped accordingly so that the tab  154 ″ can enter the notch  140 ″. This is one way of providing for a non-destructive release mechanism to guard against too much applied force and, therefore, to protect the integrity of the cord  102 / 104 . In other words, if excess tension is applied to clasp, it will disengage, without first requiring that the shaft member be rotated (“safety release”).  
         [0055]    [0055]FIG. 7 illustrates an alternate embodiment of the invention wherein at least two spring elements are provided. In this example, three spring elements  150   a ,  150   b  and  150   c  are provided, each disposed on an external surface of the latch element  110 A, and affixed thereto such with affixing means such as a rivet  156   a ,  156   b  and  156   c , respectively. The spring elements  150   a ,  150   b  and  150   c  have an elongate body portion  152   a ,  152   b ,  152   c , respectively, and a tab  154   a ,  154   b  and  154   c  extending through a corresponding hole (compare  122 ) in the wall  120 A of the latch element  110 A. The three spring elements  150   a ,  150   b  and  150   c  are suitably disposed at equal intervals (e.g., 120 degrees) about the circumference of the latch element  110 A, as illustrated. The three tabs  154   a ,  154   b  and  154   c  can all be at the same longitudinal position (e.g., distance from the front end) of the latch element  110 A, or they can be at different distances from the front end of the latch element  110 A.  
         [0056]    The shaft element  130 A has three notches  140   a ,  140   b  and  140   c . The notches  140   a ,  140   b  and  140   c  are located so as to receive a corresponding one of the three tabs  154   a ,  154   b  and  154   c , respectively. If the tabs are at different distances from the front end of the latch element  110 A, the notches would be at corresponding different distances from the front end of the shaft element  130 A.  
         [0057]    [0057]FIG. 7 shows the clasp engaged. To disengage the clasp, the shaft element  130 A would be rotated (e.g., 60 degrees) with respect to the latch element  110 A, urging the tabs  154   a ,  154   b  and  154   c  out of the respective notches  140   a ,  140   b  and  140   c , then pulling the shaft member  130 A out of the latch member  110 A.  
         [0058]    [0058]FIG. 8 illustrates an alternate embodiment of the latch member  810 , (compare the latch member  110  of FIG. 1). The latch member  810  is elongate and is generally cylindrical (tubular), having a front end  812 , a rear end  814  which is opposite the front end  812 , an inside surface  816 , and an outside surface  818 . The latch member  810  is open at the front end  812  and, in this example, is closed at the rear end  814 . The latch member  810  has an inside diameter D 1 , and its inside surface  816  is preferably of uniform diameter, rather than tapered. The outside surface  818  is shown as being of uniform diameter, but it need not be. The latch member  810  has a cylindrical wall  820 . Here, it is shown that the rear end  814  is closed with a plug  815 , but the plug could be integral with (a part of) the wall  820 .  
         [0059]    In this example, there is no separate spring member  150  with a hook (tab) portion  154 . Rather, the wall  820  of the latch member  810  itself forms a spring member  850  having a body portion  852  and a hook (tab) portion  854 . The spring member  850  is formed integrally with the latch member  810 . The body portion  852  would have a width (circumferential extent) comparable to that of the body portion  152 . The tab portion  854  is formed like the previously-described tab portion  154 , and extends resiliently into the interior of the latch member  810  to engage a corresponding notch in the pin member  130  (such as has been shown with respect to FIG. 3).  
         [0060]    While the invention has been described in combination with embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing teachings. Accordingly, the invention is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and scope of the appended claims.