Description SCREWING TYPE COUPLING STRUCTURE

Technical Field

[1] The present invention relates to coupling structures. More particularly, this invention relates to the structural improvement of external and thread coupling parts and to a screw thread coupling structure that can allow the external-thread and internal-thread coupling parts to be rapidly coupled to each other. Background Art

[2] In conventional art, external-thread coupling parts and internal-thread coupling parts are configured in such a way that threads are formed on their whole body, so they rotate relatively to each other from their ends in order to be coupled to each other.

[3] Therefore, they must rotate as many times as the number of threads, which reduces the causes the coupling speed late and is inconvenient for the user.

[4] Moreover, if external-thread coupling parts and internal-thread coupling parts are rotated to each other in a state where they are not aligned correctly from the initial time, their threads are damaged, and they cannot be correctly coupled to each other. Therefore, they require users to correct the aligning work. Disclosure of Invention Technical Problem

[5] The present invention solves the above problems, and provides a screw thread coupling structure that can allow an external-thread coupling part to enter an internal- thread coupling part in parallel direction, and can allow them to be completely coupled to each other by a single turn operation. Technical Solution

[6] In accordance with an exemplary embodiment of the present invention, a, the present invention provides a screw thread coupling structure including: an external-thread coupling part forming external-thread formed sides and external-thread not formed sides on the outer surface thereof, where each of the external-thread formed sides forms threads with an arc angle, along a helical track of the external-thread coupling part, and the external-thread not formed sides, corresponding to the remaining sides other than the external- thread formed sides, form no threads; and an internal-thread coupling part forming internal-thread formed sides and internal-thread not formed sides on the inner surface thereof, where each of the internal-thread formed sides forms threads on portions corresponding to those of the external-thread not formed sides, along a helical track of the internal-thread coupling part, and the internal-thread not formed sides, corresponding to the remaining sides other than the internal-thread

formed sides, form no threads. The external-thread coupling part enters the internal- thread coupling part, in a state where the external-thread formed sides and the internal- thread not formed sides are aligned with each other in parallel, and then couples therewith.

[7] Preferably, the external-thread coupling part further forms a complete external-thread part having a certain number of complete external threads, extended along the helical track of the external-thread coupling part, on the outer surface of the external-thread coupling part, at an end opposite to the end that enters the internal-thread coupling part. The internal-thread coupling part further forms a complete internal-thread part having a certain number of complete internal-threads, extended along the helical track of the internal-thread coupling part, on the inner surface of the internal-thread coupling part, at a position which the end of the external-thread coupling part is reached when the external-thread coupling part enters the internal-thread coupling part.

[8] In accordance with another exemplary embodiment of the present invention, the present invention provides a screw thread coupling structure including: an external- thread coupling part forming external-thread formed sides, external- thread not formed sides, and a complete external-thread part on the outer surface thereof, where: each of the external-thread formed sides forms partial external threads on a portion of the outer surface with an arc angle, located at a portion of the front portion of the entire length, along a helical track of the external-thread coupling part; the external-thread not formed sides, corresponding to the remaining sides other than the external-thread formed sides, form no threads; and the complete external-thread part having a certain number of complete external threads, extended along the helical track of the external- thread coupling part, is formed on the outer surface of the external-thread coupling part, located behind the portion of front portion, with respect to the entire length; and an internal-thread coupling part forming internal-thread formed sides, internal-thread not formed sides, and a complete internal-thread part on the inner surface thereof, where: each of the internal-thread formed sides forms partial threads on portions corresponding to those of the external-thread formed sides, along a helical track of the internal-thread coupling part, in which the portions are part of the inner surface, located behind a portion receiving the external-thread coupling part; the internal-thread not formed sides, corresponding to the remaining sides other than the internal-thread formed sides, form no partial threads; and the complete internal-thread part having a certain number of complete internal threads, extended along the helical track of the internal-thread coupling part, on the inner surface of the internal-thread coupling part, at a position in front of the portion receiving the external-thread coupling part, with respect to the entire length. The external-thread coupling part enters the internal-thread coupling part, in a state where the external-thread formed sides and the internal-thread

not formed sides are aligned with each other in parallel, and then couples therewith.

[9] Preferably, the external-thread formed sides each are formed as a rectangle, a trapezoid, or a triangle, when being projected on a plane.

[10] Preferably, the external-thread formed sides each are formed as a rectangle when being projected on a plane. The internal-thread formed sides and the internal-thread not formed sides are further formed on the same periphery of the inner surface of the internal-thread coupling part, at the front portion of the complete internal-thread part. A stopper is inserted into a gap between the external-thread not formed side and the internal-thread not formed side, in a state where the external-thread coupling part is coupled to the internal-thread coupling part, and the external-thread not formed side faces the internal-thread not formed side located in front of the complete internal- thread part.

[11] Preferably, the screw thread coupling structure further includes locking protrusions on the lower edge of the external-thread formed sides of the internal-thread formed sides.

[12] Preferably, the external-thread coupling part forms marks, indicating the external- thread formed sides, on its head. The internal-thread coupling part forms marks, indicating the internal-thread not formed sides, on its outer surface.

[13] In accordance with another exemplary embodiment of the present invention, the present invention provides a stopper adapted to the screw thread coupling structure including: a first supporting plate that is curved and has a width corresponding to an arc length of the external-thread not formed side of the external-thread coupling part; a second supporting plate that is curved and has a width corresponding to an arc length of the internal-thread not formed side of the internal-thread coupling part; and supporting wires that are curved and formed at both edges of one side ends of the first and second supporting plates, respectively. The other side ends of the first and second supporting plates, opposite the one side with the supporting wires, are connected to each other so that the one side with the supporting wires can be spaced apart from each other at a certain distance.

[14] Preferably, the first supporting plate has the same curvature as the external-thread not formed side, and the second supporting plate has the same curvature as the internal- thread not formed side.

[15]

Advantageous Effects

[16] As described above, the screw thread coupling structure according to the present invention can allow an external-thread coupling part to enter an internal-thread coupling part in parallel direction, and can allow them to be completely coupled to

each other by a single turn operation. Brief Description of Drawings

[17] The features and advantages of the present invention will become more apparent from the following detailed description in conjunction with the accompanying drawings, in which: [18] Figure 1 is a perspective view illustrating the external and internal- thread coupling parts of a screw thread coupling structure, according to a first embodiment of the present invention;

[19] Figure 2 is a partially cross-sectional side view illustrating the external and internal- thread coupling parts of a screw thread coupling structure, according to a first embodiment of the present invention; [20] Figure 3 is a cross-sectional plan view illustrating the external and internal-thread coupling parts of a screw thread coupling structure, according to a first embodiment of the present invention; [21] Figure 4 is a cross-sectional side view illustrating the external and internal-thread coupling parts of a screw thread coupling structure, according to a second embodiment of the present invention; [22] Figure 5 is a partially perspective view illustrating a container to which the screw thread coupling structure according to the second embodiment of the present invention is applied; [23] Figure 6 is a cross-sectional view illustrating a tube type packing mounted to a cap of a container to which the screw thread coupling structure according to the second embodiment of the present invention, is applied; [24] Figure 7 is a perspective view illustrating a doorknob to which the screw thread coupling structure, according to the second embodiment of the present invention, is applied; [25] Figure 8 is a cross-sectional side view illustrating the external and internal-thread coupling parts of a screw thread coupling structure, according to a third embodiment of the present invention; [26] Figure 9 is a cross-sectional side view illustrating the external and internal-thread coupling parts of a screw thread coupling structure, according to a fifth embodiment of the present invention; [27] Figure 10 is a cross-sectional side view illustrating the external and internal-thread coupling parts of a screw thread coupling structure, according to a sixth embodiment of the present invention; [28] Figure 11 is a cross-sectional side view illustrating the external and internal-thread coupling parts of a screw thread coupling structure, according to a seventh em-

bodiment of the present invention;

[29] Figure 12 is a perspective view illustrating a stopper adapted to a the screw thread coupling structure according to the seventh embodiment of the present invention;

[30] Figure 13 is a perspective view illustrating a use state of the stopper shown in Figure

12;

[31] Figure 14 is an exploded perspective view illustrating an electric wire bolt to which the screw thread coupling structure according to the second embodiment of the present invention is applied;

[32] Figure 15 is a cross-sectional view illustrating a coupling structure of the electric wire bolt shown in Figure 14;

[33] Figure 16 shows plan and side views of an embodiment of a washer that can be used for the screw thread coupling structures according to the first to seventh embodiments of the present invention;

[34] Figure 17 shows plan and side views of another embodiment of a washer that can be used for the screw thread coupling structures according to the first to seventh embodiments of the present invention;

[35] Figure 18 is a partially cross-sectional side view illustrating a use state of the screw thread coupling structure according to the seventh embodiment of the present invention, together with a washer and stopper;

[36] Figure 19 is an exploded perspective view illustrating the external and internal-thread coupling parts of a screw thread coupling structure according to the first to seventh embodiments of the present invention, where indicating lines are added to the parts;

[37] Figure 20 is a partially cross-sectional side view illustrating external and internal- thread coupling parts of a screw thread coupling structure according to a eighth embodiment of the present invention; and

[38] Figure 21 is a cross-sectional side view illustrating an electric-light bulb and a socket to which the screw thread coupling structure according to the second embodiment of the present invention is applied. Best Mode for Carrying out the Invention

[39] Hereinafter, exemplary embodiments according to the screw thread coupling structure of the present invention are described in detail with reference to the accompanying drawings. The same reference numbers are used throughout the drawings to refer to the same or similar parts.

[40] Figure 1 is a perspective view illustrating the external and internal-thread coupling parts of a screw thread coupling structure, according to a first embodiment of the present invention. Figure 2 is a partially cross-sectional side view illustrating the external and internal-thread coupling parts of a screw thread coupling structure,

according to a first embodiment of the present invention. Figure 3 is a cross-sectional plan view illustrating the external and internal-thread coupling parts of a screw thread coupling structure, according to a first embodiment of the present invention. As shown in Figures 1 to 3, the screw-thread coupling structure includes an external-thread coupling part 10a and an internal-thread coupling part 20a.

[41] The external- thread coupling part 10a is formed to include an external-thread formed side 12a whose surface forms screw-threads along a helical track, and an external- thread not formed side 14a on which no screw-thread is formed. The external-thread formed side 12a has a height from the outer periphery surface of the external-thread coupling part 10a. The external- thread formed side 12a has three thread portions each of which has an angle of 30 degrees at the periphery of external-thread coupling part 10a, where these three thread portions are arranged with an equal angle with respect to the center of the external-thread coupling part 10a. The external-thread not formed side 14a has also three no-thread portions each of which has an angle of 90 degrees at the periphery of the external-thread coupling part 10a, where these three no-thread portions are arranged with an equal angle, between the three thread portions of the external-thread formed side 12a, with respect to the center of the external-thread coupling part 10a. A complete external-thread part 16a is formed, with a single complete external-thread, extended along the thread track of the external-thread coupling part 10a, on the outer surface of the external-thread coupling part 10a, at an end opposite to the end that enters the internal-thread coupling part 20a. It should be understood that the complete external-thread part 16a may be implemented to have one or more complete external threads. Since the complete external-thread part 16a is formed at the opposite end of the external-thread coupling part 10a, the external coupling part 10a can enter the internal- thread coupling part 20a in parallel.

[42] The internal-thread coupling part 20a is formed to include an internal-thread formed side 22a whose surface forms screw-threads along a helical track, and an internal- thread not formed side 24a on which no screw thread is formed.

[43] The internal-thread formed side 22a has a height from the inner periphery surface of the internal-thread coupling part 20a. The internal-thread formed side 22a has three thread portions each of which has an angle of 30 degrees at the inner periphery of the internal-thread coupling part 20a. The internal-thread formed side 22a is formed corresponding to the external-thread not formed side 14a, so that the internal-thread formed side 22a can be correspondingly coupled with the external-thread not formed side 14a when the external-thread coupling part 10a starts to be coupled with the internal-thread coupling part 20a. The internal-thread not formed side 24a has three no thread portions each of which has an angle of 90 degrees at the inner periphery of the internal-thread coupling part 20a and is located between three thread portions of the internal-thread

formed side 22a. A complete internal-thread part 26a is formed, with a single complete internal thread, extended along the thread track of the internal-thread coupling part 20a, on the inner surface of the internal-thread coupling part 20a, at a position which the end of the external- thread coupling part 10a is reached when the external-thread coupling part 10a enters the internal-thread coupling part 20a. It should be understood that the complete internal-thread part 26a may be implemented to have one or more complete internal threads. The complete internal-thread part 26a is formed at the one end of the internal-thread coupling part 20a, so that the external-thread coupling part 10a can enter the internal-thread coupling part 20a, in parallel.

[44] As shown in Figure 3, if the external-thread coupling part 10a is aligned with the internal-thread coupling part 20a in such a way that the external-thread formed side 12a and the external-thread not formed side 14a correspond to the internal-thread not formed side 24a and the internal-thread formed side 22a, and then as they relatively move toward each other, in parallel, the external- thread formed side 12a enters the space formed by the internal-thread not formed side 24a, and the outer space of the external-thread not formed side 14 receives the internal- thread formed side 22a. Therefore, the external- thread coupling part 10a can be inserted into the internal- thread coupling part 20a, by a certain length, without rotation. The external-thread coupling part 10a can enter the internal-thread coupling part 20a until the threads of the external-thread formed side 12a contacts the complete internal thread of the complete internal-thread part 26a of the internal-thread coupling part 20a. In this stage, the external-thread coupling part 10a and the internal-thread coupling part 20a are relatively rotated to each other, so that they can be coupled to each other.

[45] The threads of the external and internal-thread coupling parts 10a and 20a are formed along the helical tracks of the external and internal-thread coupling parts 10a and 20a, respectively. The helical tracks of the external and internal-thread coupling parts 10a and 20a refer to screw-thread tracks that can be screw-coupled to each other. Therefore, the threads of the external-thread coupling part 10a can be screw-coupled to those of the internal-thread coupling part 20a.

[46] In order to separate the external-thread coupling part 10a from the internal-thread coupling part 20a, the external-thread formed side 12a is aligned with the internal- thread not formed side 24a in parallel, and then the external-thread coupling part 10a is moved, in parallel, against the internal-thread coupling part 20a. The alignment between the external and internal-thread coupling parts 10a and 20a can be easily performed as an indicating line is marked to the external-thread formed part and its coupling portion, which will be described later.

[47] Figure 4 is a cross-sectional side view illustrating the external and internal-thread coupling parts of a screw thread coupling structure, according to a second embodiment

of the present invention.

[48] As shown in Figure 4, the screw-thread coupling structure includes an external- thread coupling part 10b and an internal- thread coupling part 20b. The screw-thread coupling structure according to a second embodiment is similar to the first embodiment illustrated in Figures 1 to 3, except that it does not form a complete external-thread part and a complete internal-thread part. That is, the screw-thread coupling structure of the second embodiment is configured in such a way that the external-thread coupling part 10a includes an external- thread formed side 12b and external-thread not formed side 14b, and the internal-thread coupling part 20b includes an internal-thread formed side 22b and an internal-thread not formed side 24b.

[49] Unlike the first embodiment, although the external-thread coupling part 10b and the internal-thread coupling part 20b do not have a complete external-thread part and a complete internal- thread part, the external-thread coupling part 10b can be coupled with the internal-thread coupling part 20b as the external-thread coupling part 10b enters the internal-thread coupling part 20b, by a certain length, in parallel, and then they are relatively rotated to each other. On the contrary, if the external-thread coupling part 10b and the internal-thread coupling part 20b are relatively rotated to each other and then the external-thread coupling part 10b is removed from the internal coupling part 20b, by a certain length, in parallel, they can be separated from each other.

[50] Figure 5 is a partially perspective view illustrating a container to which the screw thread coupling structure according to the second embodiment of the present invention is applied. As shown in Figure 5, the screw thread coupling structure is applied to the container in such a way that an external-thread coupling part is formed on the outer surface of the outlet 200 of the container and an internal-thread coupling part is formed on the internal surface of a cap 100 for engaging with the outlet 200. In an embodiment of the present invention, the external and internal-thread coupling parts are implemented to be right hand threads.

[51] An internal locking protrusion 110 is formed at the left edge with respect to the inside of the cap 100, at the lower side of the internal-thread formed side 22b.

[52] An external locking protrusion 210 is formed at the left edge with respect to viewing from the outside of the outlet, at the lower side of each external- thread formed side 12b of the external-thread coupling part that is formed on the outer surface of the outlet 200. An external locking groove 220 is formed at the right of the external locking protrusion 210, at the lower side of each external-thread formed 12b.

[53] If an internal-thread not formed side 24b inside the cap 100 is placed in parallel, in a vertical direction, to the external-thread formed side 12b formed on the outer surface of the outlet 200, and then the cap 100 is relatively moved to the outlet 200, maintaining

the parallel direction, the cap 100 can cover and receive the outlet 200 of the container. After the cap 100 completely has gone down over the container, if it is rotated, the internal threads of the internal-thread formed side 22b of the cap 100 can be screw- coupled to the external thread of the external-thread formed side 12b of the outlet 200, so that the cap 100 can be coupled to the outlet 200 of the container.

[54] The external locking groove 220 of the external-thread formed side 12b is formed to set an angle that the cap 100 must rotate, which is necessary to generate a proper magnitude of coupling force between the cap 100 and the outlet 200. That is, if the cap 100 is rotated until the internal locking protrusion 110 inside the cap 100 is locked to the external locking groove 220 of the outlet 200, a user can detect that the cap 100 and the outlet 200 is coupled to each other by the coupling force and thus can stop rotating the cap 100.

[55] On the contrary, when the cap 100 is rotated until the internal locking protrusion 110 of the internal- thread coupling part of the cap 100 is locked to the external locking protrusion 210 of the outlet 200, and then the cap 100 is moved out from that position, the cap 100 can be separated from the outlet 200. That is, the internal locking protrusion 110 and the external locking protrusion 210 serve to guide an alignment position so that the internal-thread formed side 22b and the external-thread not formed side 14b can be aligned in parallel to allow the external-thread coupling part or internal-thread coupling part to be separated from the other in parallel. In an embodiment of the present invention, the external locking protrusion 210, the internal locking protrusion 110, and the external locking groove 220 can be applicable when the cap 100 and the outlet 200 of the container are made of an elastic material.

[56] Figure 6 is a cross-sectional view illustrating a tube type packing mounted to a cap of a container to which the screw thread coupling structure, according to the second embodiment of the present invention, is applied. As shown in Figure 6, it is preferable that a tube-type packing 150 is formed in the cap 100 of the container to which the screw thread coupling structure, according to the second embodiment of the present invention, is applied. Since the screw-thread coupling structure according to the present invention is not implemented with only complete threads, formed at 360 degrees around the outer surface of the shaft of the screw-thread coupling structure, it needs to be sealed. To this end, the tube type packing 150, formed as a disc filled with air, is used to seal the space between the cap 100 and the outlet 200, as shown in Figure 5.

[57] When the cap 100 is coupled to the outlet 200, the periphery border of the tube type packing 150 is placed between the rim of the outlet 200 and the upper inside of the cap 100 and seals them. As the periphery border of the tube type packing 150 is closely pressed by the ring of the outlet 200 and the upper inside of the cap 100, its center

portion is swollen as shown in Figure 6.

[58] Figure 7 is a perspective view illustrating a doorknob to which the screw thread coupling structure, according to the second embodiment of the present invention, is applied. As shown in Figure 7, the screw thread coupling structure according to the second embodiment of the present invention is applied to the doorknob 300 in such a way that an internal-thread coupling part is formed on the inside of coupling holes 301 of the doorknob 300 and an external-thread coupling part is formed on the outer surface of fixing screws 310.

[59] Each of the fixing screws 310 forms two external-thread formed sides 12b and two external-thread not formed sides 14b on its outer surface. Similarly, each of the coupling holes 301 forms two internal-thread formed sides 22b and two internal-thread not formed sides 24b on its inner surface.

[60] The fixing screws 310 are coupled to the coupling holes 301 of the doorknob 300 as follows. When the fixing screws 310 are aligned with the coupling holes 301 of the doorknob 300, respectively, according to the method described together with Figure 2, moved thereinto in parallel, and then rotated, the threads of the external-thread formed side 12b of each of the fixing screw 310 are screw-coupled to the threads of the internal-thread formed side 22b of each of the coupling holes 301.

[61] The fixing screws 310 are separated from the coupling holes 301 of the doorknob

300 as follows. When the fixing screws 310 are rotated and aligned with the coupling holes 301 of the doorknob 300, respectively, in such a way that the external-thread formed side 12b of each of the fixing screw 310 can face the internal-thread not formed side 24b of each of the coupling holes 301, and then moves out in parallel. This alignment of the fixing screws 310 can be easily achieved by marking an indication line on the fixing screw 310, forming an external-thread coupling part, and on the coupling hole 301 of the doorknob 300, which will be described later.

[62] Figure 8 is a cross-sectional side view illustrating the external and internal-thread coupling parts of a screw thread coupling structure, according to a third embodiment of the present invention. As shown in Figure 8, the screw-thread coupling structure includes an external-thread coupling part 10c and an internal- thread coupling part 20c. In particular, the external-thread coupling part 10c has threads of a relatively short length.

[63] The external- thread coupling part 10c alternately forms an external-thread formed side 12c and an external-thread not formed side 14c on its outer surface. The external- thread formed side 12c refers to a side on which threads are formed, and the external- thread not formed side 14c refers to a side on which threads are not formed. In particular, the length of threads along the circumference of the external-thread coupling part 12c is relatively short. This causes the area of the external- thread formed

side 12c to be relatively smaller than that of the external-thread not formed side 14c.

[64] The internal-thread coupling part 20c forms internal-thread not formed sides 24c and internal-thread formed sides 22c on its inside wall. The internal-thread not formed sides 24c are formed in an area corresponding to the external-thread formed sides 12c of the external-thread coupling part 10c. Similarly, the internal-thread formed sides 22c are also formed in an area corresponding to the external-thread not formed sides 14c of the external-thread coupling part 10c.

[65] It should be understood that the embodiment can be modified in such a way that the shapes of the threads of the external-thread coupling part 10c and the internal- thread coupling part 20c may be formed to be opposite to those of the embodiment. That is, the internal-thread formed sides of the internal-thread coupling part 20c are formed to be relatively short in their length along the circumference (i.e., a relatively short arc), and the internal-thread not formed sides are formed to be relatively long along the circumference (i.e., a relatively long arc).

[66] Figure 9 is a cross-sectional side view illustrating the external and internal-thread coupling parts of a screw thread coupling structure, according to a fifth embodiment of the present invention. As shown in Figure 9, the screw-thread coupling structure is configured to include an external-thread coupling part 1Od and an internal-thread coupling part 2Od.

[67] The external- thread coupling part 1Od is configured in such a way that an external- thread formed side 12d and an external-thread not formed side 14d are alternatively formed on its outer surface, along its circumference, at its front end that first enters the internal-thread coupling part 2Od, with respect to the length direction, and a complete external-thread part 16d following the external-thread formed sides 12d and the external-thread not formed sides 14d is formed. The external-thread formed side 12d refers to a part of circumference where external threads are formed. In particular, the external-thread formed side 12d is shaped as a trapezoidal shape when being projected on a plane. The external-thread not formed side 14d refers to a part of circumference where no external thread is formed. The complete external-thread part 16d refers to a side where a certain number of complete threads are formed on the circumference.

[68] The internal-thread coupling part 2Od is configured in such a way that an internal- thread not formed side 24d and an internal-thread formed side 22d are formed on its inner wall, at the end portion receiving the external-thread coupling part 1Od, with respect to the length direction, and a complete internal-thread part 26d following the internal-thread formed side 22d and the internal-thread not formed side 24d is formed. The internal-thread not formed side 24d is formed in an area corresponding to the external-thread formed side 12d of the external-thread coupling part 1Od. The internal- thread formed side 22d forms internal threads in an area, along the helical track of the

internal-thread coupling part, where the area corresponds to that of the external-thread not formed side 14d of the external-thread coupling part 1Od. The complete internal- thread part 26d refers to a side where a certain number of complete internal threads are formed on the inner circumference of the internal-thread coupling part 2Od.

[69] The external threads of the external-thread coupling part 1Od are formed along the same helical track, and the internal threads of the internal-thread coupling part 2Od are formed along the same helical track, so that the external threads and the internal threads can be screw-coupled to each other.

[70] The screw-thread coupling structure, according to the fifth embodiment of the present invention, is configured in such a way that part of the front end of the external- thread coupling part 1Od enters the internal-thread coupling part 2Od in parallel and then the external-thread coupling part 1Od is relatively rotated with respect to the internal-thread coupling part 2Od, so that they are coupled to each other. The fifth embodiment is advantageous in that, while the external-thread coupling part 1Od is entering the internal-thread coupling part 2Od in parallel, the external threads of the external-thread coupling part 1Od and the internal threads of the internal-thread coupling part 2Od can be easily aligned with respect to each other. In order to uncouple the external-thread coupling part 1Od and the internal-thread coupling part 2Od from each other, the external- thread coupling part 1Od is relatively rotated with respect to the internal-thread coupling part 2Od until the threads of the external-thread coupling part 1Od are removed from the complete internal-thread part 26d and located at the internal-thread not formed side 24d. After that, the external- thread coupling part 1Od is, in parallel, aligned with the internal-thread coupling part 2Od and then separated therefrom.

[71] Since the external-thread formed side 12d of the external-thread coupling part 1Od and the internal-thread not formed side 24d of the internal-thread coupling part 2Od are formed as a trapezoidal shape, the external-thread coupling part 1Od can easily, in parallel, enter the internal-thread coupling part 2Od by the height of the trapezoidal shape of the external-thread formed side 12d or the internal- thread not formed side 24d, without a pre-alignment process therebetween. Furthermore, after the external- thread coupling part 1Od has entered the internal- thread coupling part 2Od, as the number of coupling rotations of the external- thread coupling part 1Od increases with respect to the internal-thread coupling part 2Od, the external-thread coupling part 10 and the internal-thread coupling part 2Od are coupled to each other while the thread coupling between the external-thread coupling part 10 and the internal- thread coupling part 2Od becomes closer to complete thread coupling. Therefore, the external-thread coupling part 10 and the internal-thread coupling part 2Od can be tightly coupled to each other. This effect can be accomplished by the following screw-thread coupling

structures shown in Figures 10 and 11. Figure 10 shows a screw-thread coupling structure whose thread formed side is a triangular shape, followed by a complete thread part. Figure 11 shows a screw-thread coupling structure whose thread formed side is a rectangular shape, followed by a complete thread part.

[72] Figure 10 is a cross-sectional side view illustrating the external and internal-thread coupling parts of a screw thread coupling structure, according to a sixth embodiment of the present invention. As shown in Figure 10, the screw-thread coupling structure of the sixth embodiment is configured to include an external-thread coupling part 1Oe and an internal-thread coupling part 2Oe. The screw-thread coupling structure of the sixth embodiment is similar to the fifth embodiment shown in Figure 9, except for the shapes of an external-thread formed side 12e of the external-thread coupling part 1Oe, an external-thread not formed side 14e, an internal-thread formed side 22e, and an internal-thread not formed side 24e. The external-thread formed side 12e is shaped as a triangle when being projected on a plane. The external-thread not formed side 14e, the internal-thread formed side 22e, and the internal-thread not formed side 24e are also formed to meet the shape of the external-thread formed side 12e.

[73] Figure 11 is a cross-sectional side view illustrating the external and internal-thread coupling parts of a screw thread coupling structure, according to a seventh embodiment of the present invention. As shown in Figure 11, the screw-thread coupling structure of the seventh embodiment is configured to include an external-thread coupling part 1Of and an internal-thread coupling part 2Of.

[74] The external- thread coupling part 1Of is configured in such a way that an external- thread formed side 12f and an external-thread not formed side 14f are alternatively formed on its outer surface, along its circumference, at its front end, and a complete external-thread part 16f, following the external-thread formed sides 12f and the external-thread not formed sides 14f, is formed. The external-thread formed side 12f refers to a part of circumference where external threads are formed along the helical track of the threads. The external-thread not formed side 14f refers to a part of circumference where no external thread is formed. The complete external- thread part 16f refers to a side where a certain number of complete threads are formed on the circumference along the helical track of the threads.

[75] The internal-thread coupling part 2Of is configured in such a way that an internal- thread not formed side 24f and an internal-thread formed side 22f are formed on its inner wall, at a rear end portion receiving the external-thread coupling part 1Of, with respect to the length direction. The internal-thread not formed side 24f is formed in an area corresponding to the external-thread formed side 12f of the external-thread coupling part 1Of. The internal-thread formed side 22f forms internal threads in an area, along the helical track of the internal-thread coupling part, where the area cor-

responds to that of the external-thread not formed side 14f of the external- thread coupling part 1Of. The internal-thread coupling part 2Of is also configured to form a complete internal- thread part 16f on its inner wall, next to the internal-thread formed side 22f and the internal-thread not formed side 24f, i.e., at the front direction of the internal-thread formed side 22f and the internal-thread not formed side 24f. The complete internal-thread part 26f refers to a part where complete internal threads are formed on the inner circumference of the internal-thread coupling part 2Of. In particular, the internal-thread coupling part 2Of is further configured to form another internal-thread not formed side 24f and another internal-thread formed side 22f on its inner wall, at the front direction of the complete internal-thread part 26f. That is, another internal-thread not formed side 24f and another internal-thread formed side 22f, located in front of the complete internal-thread part 16f, are the same as those located at the rear of the complete internal-thread part 16f.

[76] The external-thread coupling part 1Of and the internal-thread coupling part 2Of can be coupled to each other as follows. The external-thread formed side 12f is relatively aligned with the internal-thread not formed side 24. The external-thread coupling part 1Of enters the internal-thread coupling part 2Of, in parallel, until it reaches the complete internal-thread part 26f. The external-thread coupling part 1Of and the internal-thread coupling part 2Of are relatively rotated to each other until the front end of the external-thread coupling part 1Of extends through the internal-thread coupling part 2Of.

[77] If the external-thread coupling part 1Of, having been coupled with the internal-thread coupling part 2Of, is relatively aligned with the internal-thread coupling part 2Of so that the external-thread not formed side 14f can face the internal-thread not formed side 24f, a gap is generated between the external-thread not formed side 14f and the internal-thread not formed side 24f. This gap can be filled with a stopper 30 which will be described later.

[78] Figure 12 is a perspective view illustrating a stopper adapted to the screw thread coupling structure according to the seventh embodiment of the present invention. Figure 13 is a perspective view illustrating a use state of the stopper shown in Figure 12. As shown in Figure 12, the stopper 30 is configured to include first and second supporting plates 31 and 33, connected at their one-side ends and separated at their opposite side ends, and supporting wires 32 that are formed at both edges at each one side end of the first and second supporting plates 31 and 33.

[79] The first supporting plate 31 is curved and has a width corresponding to the arc length of the external- thread not formed side 14f. The first supporting plate 31 has the same curvature as the external-thread not formed side 14f. This is to improve the proximity of the first supporting plate 31 and the external- thread not formed side 14f.

The first supporting plate 31 may have a curvature, which is not equal to that of the external-thread not formed side 14f though. That is, the curvature of the first supporting plate 31 can be allowed if it is extended in such a way that the first supporting plate 31 can be inserted into the gap between the external-thread not formed side 14f and the internal-thread not formed side 24f.

[80] The second supporting plate 33 is curved and has a width corresponding to the arc length of the internal-thread not formed side 24f. The second supporting plate 33 has the same curvature as the internal-thread not formed side 24f.

[81] The first and second supporting plates 31 and 33 are formed in such a way that then- one side ends are connected to each other and their opposite side ends are spaced apart from each other. They can be resiliently deformed to reduce the spaced distance between their opposite side ends.

[82] The first and second supporting plates 31 and 33 form supporting wires 32 at their both edges of the opposite side ends, respectively. The supporting wires 32 are curved. It is preferable that the stopper 30 may be manufactured with magnetic materials so that, after inserted into the gap, it cannot be removed therefrom.

[83] As shown in Figure 13, when the stopper 30 is inserted into the gap between the external-thread not formed side 14f and the internal-thread not formed side 24f, both the supporting wires 32 of the second supporting plate 33 of the stopper 30 are caught by the thread of the external-thread formed side 12f of the external-thread coupling part 10, so the stopper 30 is placed therein and is not be easily removed therefrom. Therefore, the external- thread coupling part 10 and the internal-thread coupling part 20 can be no longer rotated with respect to each other by the stopper 30. The stopper 30 can be removed from the gap as tweezers pull out the supporting wires 32 of the first supporting plate 31 of the stopper 30.

[84] If the first and second supporting plates 31 and 33 are resilient and deformable, the stopper 30 is not easily removed from the thread coupling structure even by the occurrence of vibration.

[85] Figure 14 is an exploded perspective view illustrating an electric wire bolt to which the screw thread coupling structure according to the second embodiment of the present invention is applied. Figure 15 is a cross-sectional view illustrating a coupling structure of the electric wire bolt shown in Figure 14. As shown in Figures 14 and 15, the anchor bolt 420 and the electric wire bolt 440, installed to the ceiling 410, employ the external-thread coupling part of the screw-thread coupling structure according to the second embodiment of the present invention. The joint 430 and the nut 450, each of whose inside is hollow, employ the internal-thread coupling part of the screw-thread coupling structure according to the second embodiment of the present invention.

[86] A plane washer 422 and a spring washer 424 are installed onto an anchor bolt 420

protruded from the ceiling 410, and then a nut 450 is coupled to the anchor bolt 420. After that, the nut 450 is fixed to the anchor bolt 420 by a stopper 30. Next, a joint 430 is installed onto the lower end portion of the anchor bolt 420, and then an electric wire bolt 440 is coupled to the lower end portion of the joint 430. Afterwards, a stopper 30 is inserted between the lower end portion of the joint 430 and the electric wire bolt 440, and thus the electric wire bolt 440 is fixed to the joint 430.

[87] The electric wire bolt 440 extends its lower portion through the coupling hole of an object 460 to be supported. A nut 450 is coupled to the lower portion of the electric wire bolt 440, extended through the object 460. After that, the electric wire bolt 440 and the nut 450 are aligned in such a way that the external-thread not formed side 14b and the internal-thread not formed side 24b face to each other and then a stopper 30 is inserted therebetween.

[88] It should be understood that the anchor bolt 420, nut 450, joint 430, and electric wire bolt 440 enter or receive each other, in parallel, and then are rotated and coupled to each other at a time, like the coupling method of the screw-thread coupling structure according to the second embodiment of the present invention.

[89] Figure 16 shows plan and side views of an embodiment of a washer that can be used for the screw thread coupling structures according to the first to seventh embodiments of the present invention. As shown in Figure 16, the washer 40 is formed as a ring that is partially open in the radial direction and waved in the radial direction. In particular, the washer 40 forms a scratched part 42 on each of the upward convex portion, where the scratched part 42 is uneven and enhances the frictional force.

[90] Figure 17 shows plan and side views of another embodiment of a washer that can be used for the screw thread coupling structures according to the first to seventh embodiments of the present invention. As shown in Figure 17, the washer 50 is formed as a rim on whose upside and downside semispherical protrusions 52 are formed alternatively.

[91] When the washer 50 is placed between objects, it can increase the frictional force as the semispherical protrusions generate plastic deformation against objects.

[92] Figure 18 is a partially cross-sectional side view illustrating a use state of the screw thread coupling structure according to the seventh embodiment of the present invention, together with a washer and stopper. As shown in Figure 18, the external- thread coupling part 1Of and the internal-thread coupling part 2Of corresponds to the external-thread coupling part 1Of and the internal-thread coupling part 2Of according to the seventh embodiment. The external-thread coupling part 1Of extends through coupling holes of coupling members 510 and 520 and allows a washer 50 to be installed thereonto. After that, the external- thread coupling part 1Of is coupled to the internal-thread coupling part 2Of. In such a state, the external-thread coupling part 1Of

and the internal-thread coupling part 2Of are aligned with each other, and then a stopper 30 of Figure 12 is inserted therebetween. From these series of operations, the coupling state between the external-thread coupling part 1Of and the internal- thread coupling part 2Of is firstly maintained by the washer 50, and secondly is maintained by the stopper 30. In order to enhance the appearance, a cap 60 having a magnet 62 may further cover the lower end of the external-thread coupling part 1Of.

[93] Figure 19 is an exploded perspective view illustrating the external and internal-thread coupling parts of a screw thread coupling structure according to the first to seventh embodiments of the present invention, where indicating lines are added to the parts. As shown in Figure 19, the external and internal- thread coupling parts 10b and 20b mark arrows 18 and 28 thereon, so that a user can easily recognize the alignment state of the external and internal-thread coupling parts when they are coupled to each other in parallel.

[94] Figure 20 is a partially cross-sectional side view illustrating external and internal- thread coupling parts of a screw thread coupling structure according to a eighth embodiment of the present invention. As shown in Figure 20, the screw-thread coupling structure is configured to include an external-thread coupling part 1Og and an internal- thread coupling part 2Og, and similar to the second embodiment shown in Figure 4, except for the following points.

[95] The external- thread formed side 12g and the external-thread not formed side 14g of the external-thread coupling part 1Og are each formed to have a quarter of the circumference of the external-thread coupling part 10. Similarly, the internal-thread formed side 22g and the internal-thread not formed side 24g of the internal-thread coupling part 2Og are each formed to have a quarter of the circumference of the internal-thread coupling part 2Og.

[96] Figure 21 is a cross-sectional side view illustrating an electric-light bulb and a socket to which the screw thread coupling structure according to the second embodiment of the present invention is applied. As shown in Figure 21, the electric bulb 610 forms an external-thread coupling part 10b on its end portion to be coupled to the socket 620. The external-thread coupling part 10b is formed to include an external-thread formed side 12b, whose arc length is 1/6 of the circumference of the external-thread coupling part 10b, and an external-thread not formed side 14b whose arc length is 2/6 of the circumference of the external-thread coupling part 10b.

[97] The socket 620 forms an internal-thread coupling part 20b on the inner wall to be coupled to the end portion of the electric bulb 610. The internal-thread coupling part 20b is formed to include an internal-thread formed side 22b, whose arc length is 1/6 of the circumference of the internal-thread coupling part 20b, and an internal-thread not formed side 24b whose arc length is 2/6 of the circumference of the internal-thread

coupling part 20b.

[98] The external- thread formed side 12b of the bulb 610 is aligned with the internal- thread not formed side 24b of the socket, in parallel, and then the bulb 610 moves to the socket 620. After that, when the bulb 610 and the socket 620 are relatively rotated to each other, once, they can be coupled to each other.

[99] The screw-thread coupling structure according to the present invention can be applied to all conventional screw coupling parts, such as screws for fixing products, threads of containers and caps, etc. It can also be applied to conventional screws.

[100] Since the threads of the screw-thread coupling structure according to the present invention are formed smoothly by chamfering their edges, thereby providing coupling convenience.

[101] The number of threads of the external-thread formed sides and the internal-thread formed sides are purely illustrative in order to explain embodiments of the present invention. Therefore, it should be understood that the threads can be implemented with a variety of numbers. The external-thread formed sides and the internal-thread formed sides can be also implemented with a variety of numbers according to the use environment.

[102] The thread formed sides and thread not formed sides can be formed symmetrically or asymmetrically on the external-thread coupling part and the internal-thread coupling part.

[103] It should be understood that the screw-thread coupling structure according to the present invention, as shown in Figure 5, which includes the locking protrusions and locking grooves, formed in the external-thread coupling part and the internal-thread coupling part is not limited to the embodiment which is shown in Figure 5. It will be appreciated that the screw-thread coupling structure according to the present invention, as shown in Figure 5, which includes the locking protrusions and locking grooves, formed in the external-thread coupling part and the internal-thread coupling part, can be applied to a variety of applications, such as the electric light bulb and socket shown in Figure 21.

[104] It will also be appreciated that the screw-thread coupling structure according to the present invention can be applied to the systems, products, and building coupling members, etc., only if they have a coupling structure.

[105] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Industrial Applicability

Since the screw-thread coupling structure is configured to include structurally improved external and thread coupling parts, it can easily and rapidly achieve a coupling process, so widely used in areas using coupling structures.