Patent Publication Number: US-7219406-B2

Title: Buckle with safety latch

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to plastic snap buckles and more specifically relates to a snap buckle with a safety latch to prevent it from accidental release. 
   2. Background of the Invention 
   Plastic snap buckles are widely used for securing mounting belts for a large variety of bags and harnesses. Such snap buckle consists of a male plug and a female receptacle. The male plug is mounted to the end of one belt and the female receptacle is mounted to the end of the other belt such that the male plug and the female receptacle may be slidably engaged with one another to secure the two belts together. The male plug has two flexible arms which will engage with two side openings in the female receptacle when the male plug is slidably inserted into the female receptacle. To release the engagement, the flexible arms are pushed and held inwards towards one another while pulling the male plug away from the female receptacle. The engagement and release may be executed easily and quickly. Such plastic buckles are convenient to use and may be produced with relatively low cost. However, the buckle may become released accidentally when the flexible arms of the male plug are pushed in inadvertently either by hand or by abutting to other objects. More often, due to wear and tear in use, the engagement of the two components becomes less positive and it may be disengaged by a slight force exerted to the flexible arms of the male plug. Furthermore, when such buckle is used on the securing belt of a waist bag or wallet, the latter may be easily removed by some one forcibly gripping the flexible arms of the male plug to release the buckle to remove the worn bag. Thus, it becomes rather unsafe to use the buckle for such purposes. To prevent such forcible release and removal, safety latch may be provided in the buckle. However, theretofore, the safety latch constructions are rather complex in structure and are difficult to operate or the safety latch may itself be accidentally unlatched. 
   SUMMARY OF THE INVENTION 
   It is a principal object of the present invention to provide a snap buckle having a safety latch which operates effectively to prevent accidental or unintended release of the buckle. 
   It is another object of the present invention to provide a snap buckle having a safety latch which is itself protected from inadvertent release. 
   It is another object of the present invention to provide a snap buckle having a safety latch which is simple in structure yet is easy to operate. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments thereof in connection with the accompanying drawings in which 
       FIG. 1  is a perspective top elevation view of the snap buckle according to the present invention with the male plug engaged within the female receptacle. 
       FIG. 2  is a perspective bottom elevation view of the snap buckle according to the present invention with the male plug shown in dotted line. 
       FIG. 3  is an exploded top elevation view showing the male plug and the female receptacle separated from one another. 
       FIG. 4  is an exploded bottom elevation view of that shown in  FIG. 3 . 
       FIG. 5  is a perspective top elevation view of the male plug showing the latch member located at the latched position to prevent the flexible arms of the male plug from being pushed inwards. 
       FIG. 6  is a perspective bottom elevation view of  FIG. 5 . 
       FIG. 7  is an enlarged cross sectional side elevation view along cross section line VII—VII of  FIG. 2 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   With reference to the drawings in which like reference numerals designate corresponding parts in the several views, the snap buckle  10  of the present invention includes a male plug  11  and a shell-like female receptacle  12  which may engage with one another for securing two belts together. The male plug  11  has a main frame  13  with an end mounting bar  14  adapted for mounting to an end of one belt and the female receptacle  12  also has an end mounting bar  15  adapted for mounting to an end of the other belt. These belts may be harness belts for mounting a carrying bag or a waist wallet or the like to a person. Two parallel spaced flexible arms  17  and  18  extend outwards from the main frame  13  opposite to the end mounting bar  14 . The free ends of the flexible arms  17  and  18  have enlarged arcuate portions  19  and  20  respectively extending inwards towards one another and two rearwardly facing hooks  19 A and  20 A are formed on the outer side of the flexible arms  17  and  18  adjacent to the rear end of the arcuate portions  19  and  20 . An elongated bar  21  is located at the middle of a cross bar  22  of the main frame  13  opposite to the end mounting bar  14  and equally spaced from the flexible arms  17  and  18 . An elongated open slot  23  is formed in the center portion of the elongated bar  21 . 
   A generally rectangular latch member  24  is slidably mounted on the elongated bar  21 . The latch member  24  has an inverted T-shaped pin  25  located at its bottom surface. The inverted T-shaped pin  25  slidably engages with the open slot  23  for mounting the latch member  24  on the elongated bar  21  such that the latch member  24  may be slidable relative to the elongated bar  21 . The latch member  24  has a length equal to the distance between the arcuate portions  19  and  20  of the flexible arms  17  and  18  so that when the latch member  24  is slidably located at the position between the arcuate portions  19  and  20  of the flexible arms  17  and  18 , it prevents the flexible arms  17  and  18  from being pushed inwards towards each other. It can be appreciated that the latch member  24  may alternatively be oval, triangular or multi-sided in shape to provide the same function as long as it has a length equal to the space between the arcuate portions  19  and  20  of the flexible arms  17  and  18 . The latch member  24  has a flexible extension arm  26  which normally extends rearwards parallel to the elongated bar  21  and it is flexible in the up and down directions relative to the elongated bar  21  in a cantilever manner. A raised button portion  27  is formed at the end portion of the upper surface of the extension arm  26 . 
   The female receptacle  12  has a shell-like body with two arcuate openings  28  and  29  formed at its two sides. The shell-like body has an upper wall  30  and a lower wall  31 . The male plug  11  may be inserted into the female receptacle  12  through its front opening  32  until the hooks  19 A and  20 A of the male plug  11  engage with the rear edge of the arcuate opening  28  and  29  in a snap action to retain the two parts together. 
   An elongated slot opening  32  formed at the central portion of the lower wall  31  parallel to the central longitudinal axis of the female receptacle  12 . The width of the slot opening  32  is equal to the width of the raised button portion  27  of the extension arm  26  such that when the male plug  11  and fully inserted into the female receptacle  12  the raised button portion  27  is slidably engaged with the slot opening  32 . During the insertion of the male plug  11  into the female receptacle  12  the extension arm  26  is bent in a cantilever manner by the inner surface of the female receptacle until the raised button portion  27  engages with the slot opening  32  in a snap action to position slightly below the lower wall  31  of the female receptacle  12 . After the male plug  11  and the female receptacle  12  have locked together in a snap action with the arcuate portions  19  and  20  of the male plug  11  engaged with the arcuate openings  28  and  29 , the latch member  24  may be moved forward slidably to the position between the arcuate portions  19  and  20  by pushing the raised button  27  so as to prevent the flexible arms  17  and  18  from being pushed inwards towards each other to release the engagement between the male plug  11  and the female receptacle  12 . The buckle  10  may be released only by sliding the latch member  24  forward to the position away from the space between the arcuate portions  19  and  20  of the flexible arms  17  and  18  of the male plug  11  so that the flexible arms  17  and  18  may be squeezed inwards to disengage from the arcuate openings  28  and  29  in order the male plug  11  and the female receptacle  12  may be pulled apart from the locked engagement. Since the raised button  27  of the latch member  24  is located in the slot opening  26  at the lower wall  31  of the female receptacle  12 , it is not accessible unless the buckle  10  is turned over upside down. As the belt is tightly mounted to the body of the person, such action is difficult to carry out without the cooperation of the person wearing the device. Thus, it prevents the latch member  24  from being inadvertently operated by abutting to other object or the buckle being operated forcibly to remove the device worn by the person. 
   While the present invention has been shown and described in the preferred embodiment thereof, it will be apparent that various modifications can be made therein without departing from the spirit or essential attributes thereof, and it is desired therefore that only such limitations be placed thereon as are imposed by the appended claims.