in the present invention a base piece 1 having thereon an ornamental piece a is fitted at its coupling portion 1a into an opening 3a of the recess 3 of a receiving member 2 , and the projection 1b is inserted into a step - shaped engaging guide groove 4 from the upper opening end of the upper groove portion 4a . the coupling portion 1a is then turned along the intermediate groove portion 4b and , at the end position thereof , is further pushed inwards along the lower groove portion 4c to non - rotatably connect the base piece 1 inside the recess 3 . in this condition the base piece 1 and the receiving member 2 are magnetically connected to each other by means of the magnet pieces 5 , 5 . in order to detach the base piece 1 from the receiving member 2 under this condition , an operation which is opposite in sequence to the coupling operation described above must be performed , namely , by first pulling the base piece 1 along the lower groove portion 4c against the magnetic coupling force , then turning it along the intermediate groove portion 4b in the direction opposite to that used for coupling the base piece 1 and further pulling the projection lb out of the upper groove portion 4a . however , it is highly unlikely , if not impossible , that the operation of pulling the base piece 1 upwards against the magnetic coupling force , then turning it and further pulling it out of the recess in the mentioned sequential order could occur due to natural external forces while the ornamental piece a is in use . such operation is performed only manually and , therefore , the base piece 1 cannot be inadvertently dropped off from the receiving member 2 while in use . this ensures the coupling of the base piece 1 to the receiving member 2 . for connecting the base piece 1 and the receiving member 2 , the opening 3a of the recess 3 of the receiving member 2 can be formed in the same shape as the projected shape of the coupling portion 1a of the base piece 1 as well as having a projection 6 on part of its external surface . in this manner , the fitting and connecting movements of the connecting portion 1a relative to the recess 3 is facilitated . further , as a result of a complementary fitting and secure connection between the step - shaped engaging guide groove 4 and the projection 1b , the coupling portion 1a contacts the bottom surface 3b of the recess 3 wherein the coupling portion 1a and the bottom surface 3b are connected together without clearance in between due to the complementary shapes of both , thereby securing a firm connecting condition . in this case it is preferable that at least the bottom surface 3b of the recess 3 be formed in the same shape as the coupling portion 1a to secure a firm connection . however , the relative shapes of the coupling portion 1a and the recess 3 need not necessarily be the same ; as illustrated in fig9 for example , the coupling portion 1a and the recess 3 may have different shapes from each other provided that the coupling portion la may be able to rotate within the recess 3 without large deviation of the coupling portion from its predetermined position . accordingly , it is still possible to detachably connect the coupling portion 1a and recess 3 together even though they differ in shape . an embodiment of the present invention will now be described with reference to fig1 and 2 . reference numeral 1 denotes a base piece having a jewel or any other accessory piece a integrally mounted thereon , and reference numeral 2 denotes a receiving member to which the base piece 1 is coupled . in the illustrated embodiment , the receiving member 2 is a component of the accessory and is used in combination with the base piece 1 fitted into and connected within a recess 3 provided in the receiving member 2 . on the coupling portion 1a , which is inserted into the recess 3 of the receiving member 2 , there are provided projections 1b comprising projectingly mounted pins on part of its external surface . the opening 3a and the bottom surface of the recess 3 of the receiving member 2 , into which the coupling portion 1a of the base piece 1 is inserted , are formed in a complementary shape to the projected shape of the coupling portion 1a including the projections 1b for receiving the same . the base piece 1 and the coupling portion 1a of the illustrated example are integrally combined together . the cross section of the base piece 1 is circular with projections 1b formed in diametrically opposite positions . in the opening 3a and in the bottom surface 3b of the recess 3 of the receiving member 2 , openings ( slots ) 3c which conform to the projections 1b for receiving the same are formed in the circular edges . on the internal circumferential surface of the recess 3 there are provided step - shaped engaging guide grooves 4 each of which comprises an opening ( slot ) 3c as an upper opening on the upper circumferential edge , an upper groove portion 4a which extends from the opening 3c towards the bottom , an intermediate groove portion 4b which bends from the end of the upper groove and which extends along the circumferential direction , and a lower groove portion 4c which bends from the remaining end of the intermediate groove portion and which extends further towards the bottom . the number of the projections 1b and the step - shaped engaging guide grooves need not be limited to two pieces as illustrated , and may be increased or decreased at will . the provision of the engaging guide groove 4 may be modified , for instance , as shown in fig3 . namely , with a receiving member 2 which is cylindrically formed , the engaging groove 4 may be provided through the entire depth of the wall of the receiving member 2 . further , magnet pieces 5 are mounted respectively on the lower end face of the coupling portion 1a of the base piece 1 and on the bottom surface 3b of the recess of the receiving member 2 , so that they may be in contact with each other or may be opposed in close proximity to each other when both are fitted and connected together . in the above construction , the coupling portion 1a of the base piece 1 is fitted into the recess 3 of the receiving member 2 , and the projections 1b of the coupling portion 1a are placed into the opening ( slot ) 3c . the coupling portion 1a is then inserted in the upper groove portion 4a of the step - shaped engaging groove 4 , is turned along the intermediate groove portion 4b and then , at the end of the intermediate groove portion 4b , is pushed in the direction of fitting , thereby firmly connecting the base piece 1 inside the recess 3 of the receiving member 2 by means of magnetic connection between magnet pieces 5 , 5 provided on the end surface of the coupling portion 1a and on the bottom surface 3b of the recess 3 . if there occurs some looseness in the joint between the base piece 1 and the receiving member 2 , the secureness of the coupling becomes uncertain . however , any looseness in the joint can be eliminated and the connection secured if those projections 1b on the coupling portion 1a are formed , for example , into a hook shape , and the cross section of the lower groove portion 4c of the engaging guide groove 4 into which the projections 1b are inserted is made to coincide with such hook - shaped projections 1b as illustrated in fig4 . the shape of the above - mentioned projections 1b need not be limited to a hook shape ; they may be formed in a t - shape or any other shapes at will . accordingly , the sectional shape of the lower groove portion 4c of the engaging guide groove 4 is formed so as to correspond to the shape of the projections 1b . another embodiment of the present invention will be described below with reference to fig5 through 8 . in this embodiment , the coupling portion 1a of the base piece 1 is formed into a shape having two projections 1b on the periphery . therefore , the recess 3 of the receiving member 2 is formed correspondingly such that the opening 3a in the recess 3 and the bottom surface 3b have the same shape as that of the peripheral shape of the coupling portion 1a . further , as illustrated in fig5 a step - shaped engaging guide groove 4 is formed on the internal circumferential surface in communication with the openings ( radially extending slots ) 3c in the recess so that the coupling portion 1a of the base piece 1 is inserted into the recess 3 of the receiving member 2 by aligning the projections 1b and the opening 3c and then is turned and is further pushed in the direction of fitting . this operation of the embodiment is not different from the foregoing embodiment . in the embodiments as shown in fig1 through 8 , there are shown examples in which the projected shapes of the coupling portion 1a and at least of the bottom surface 3b of the recess 3 are made identical . however , as illustrated in fig9 the shape of the coupling portion 1a may be rectangular or any other arbitrary shape , and the shape of the recess 3 into which the coupling portion 1a is inserted may be circular or any other shape in which the coupling portion 1a can be freely rotatable . in this case , although it is preferable that the coupling portion 1a is rotatable within the recess 3 in contacting relationship with the internal surface of the recess 3 , the projections 1b and the engaging guide groove 4 may have some allowance for movement so long as they remain within a range in which they are not apart from each other . fig1 illustrates an earring in which the coupling device of the present invention is employed , wherein a base piece 1 with an ornamental piece mounted thereon is replaceably coupled to a receiving member 2 which is a component of the earring . of course , it will be understood that the ornamental piece a can be replaced by any other pieces used for various accessories . in addition , the receiving member 2 may be attached to articles of clothing or the like and the base piece 1 with an ornamental piece a mounted thereon may be connected to the receiving member 2 in the above - described manner , thereby providing a button which can be used with various ornamental pieces a , replaced or substituted by other ornaments as required . the attachment of the receiving member 2 to articles of clothing can be achieved by any method , for example , by sewing , using holes 6a in sleeves 6 mounted on the receiving member 2 as shown by phantom line in fig5 or by inserting claws ( not shown ) projecting from the receiving member 2 through the clothing and folding them back .
according to the present disclosure , the base piece with an ornamental piece mounted thereon is coupled to the receiving member which is a part of any one of the various accessories or buttons by use of a magnetic coupling and through engagement of the projection in a special step - shaped engaging groove . therefore , attachment and detachment of the ornament are easy and particularly , because the coupling requires a device which cannot be released by natural external forces while the device is in use , the ornamental piece is reliably prevented from dropping off of the base piece while in use and replacement of the ornamental piece by any of various accessories or ornamental buttons is easily and conveniently facilitated .