P/00/011 Regulation 3.2 AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT ORIGINAL TO BE COMPLETED BY APPLICANT Name of Applicant: Nien Made Enterprise Co., Ltd. Address for Service: A.P.T. Patent and Trade Mark Attorneys PO Box 222, Mitcham, SA 5062 Invention Title: Cord release of window covering Divisional of: 2012202629 dated 4 March 2012 The following statement is a full description of this invention, including the best method of performing it known to me/us: 1 CORD RELEASE OF WINDOW COVERING CROSS-REFERENCE TO RELATED APPLICATIONS This application is a divisional of application Ser. No. 2012202629, filed 5 May 4, 2012, the entire disclosure of which is hereby incorporated by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a window covering, and more particularly to a cord release of a window covering. 10 2. Description of the Related Art FIG. 1 and FIG. 2 show a conventional cord release 1 for a window covering to connect a plurality of cords 4 and a rope 5. The cord release 1 thus can collect the cords together and at the same time user may operate the rope 5 to fold or unfold the window covering. 15 The cord release 1 includes two semi-circular cases 2 and 3 with their bottoms connected together. The case 2 has a pair of blocks 2a to engage slots 3a on the case 3. The cord release 1 has a round opening 1 a on a top thereof when the cases 2 and 3 are engaged. The cords 4 enter the cord release 1 through the opening la, and some of the cords 4 are fastened with a rib 2b on an inner side of the case 2, and the 20 rest cord 4 passes through a hole 2c and ties a knot so that the cords 4 are connected to the cord release 1. Kids may play with the cords and strangled by the cords 4. When the kid struggles, it may disengage the case 2 away with case 3 of the cord release 1 that he/she may escape from the cords 4. However, when the kid struggles, the cords may 25 be forced to push against the round opening la. But since the opening la is round, 2 the force can't concentrate at the exact location at the opening la to disengage the cases 2 and 3. The best location that the cords shall push against the opening la so to disengage the cases 2 and 3 is perpendicular to the junction plane of the cases 2 and 3 when they are engaged together. Any delay in disengagement may increase the 5 danger or hurt to the strangled kid. Besides, even when the cases 2 and 3 are disengaged, since some of the cord 4 are tied together with case 2, the cords 4 may still remain in the hole 2c and entangled with other cords 4 to strangle the kid. SUMMARY OF THE INVENTION 10 The primary objective of the present invention is to provide a cord release of a window covering, which may guide the cords to disengage the case when the kid is strangled between the cords. According to the objective of the present invention, a cord release for a window covering includes a plurality of cases engaged together to form a shell with a 15 top opening at a top thereof. A plurality of cords enter the shell through the top opening. At least one of the cases is provided with a guiding member at a top thereof, and the guiding member is located at a junction of the cases. The guiding member has a guiding face with a convex surface projecting towards the center of the top opening. In an embodiment, the top opening of the shell is elliptical with a long axis 20 and a short axis, and the junction of the cases is on the short axis. In an embodiment, the guiding member is projected from an edge of one case to engage a connecting member provided on the other case. It is preferable that the guiding member has a recess to engage a protrusion on the connecting member. In an embodiment, one of the cases has a first bore and a second bore on a 25 bottom thereof, and the other case has a third bore on a bottom thereof that a rope 3 passes through the first bore, the third bore, and the second bore in sequence. It is provided with a guiding slot or two blocks on the bottom to keep the rope section exposed outside at the bottom of the cord cases from entangling with the end portion of the rope pulled out from the cord release. 5 In an embodiment, the cases are provided with a cord fastener respectively, each of which has two slots. Each slot has an open end that the cord received in the slot may escape from the slot through the open end when the cases are disengaged. It is preferred that each cord fastener is provided with a wall underneath each slot to hold the cord. 10 The present invention further provides a cord release to connect a plurality of cords and a rope. The cord release includes at least two cases engaged together to form a shell with a top opening. The cords enter the shell through the top opening. One of the cases has a first bore and a second bore on a bottom thereof, and the other case has a third bore on a bottom thereof. The rope passes through the first bore, the 15 third bore, and the second bore in sequence. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the conventional cord release; FIG. 2 is a top view of the conventional cord release; FIG. 3 is a perspective view of a first preferred embodiment of the present 20 invention in the disengaged condition; FIG. 4 is a bottom view of the first preferred embodiment of the present invention; FIG. 5 is another perspective view of the first preferred embodiment of the present invention in the engaged condition; 25 FIG. 6 is a top view of FIG. 5; 4 FIG. 7 is a sectional view along the 7-7 line of FIG. 5; FIG. 8 is a perspective view of a second preferred embodiment of the present invention in the disengaged condition; FIG. 9 is a perspective view of a third preferred embodiment of the present 5 invention in the disengaged condition; FIG. 10 is a top view of a fourth preferred embodiment of the present invention in the disengaged condition; and FIG. 11 is similar to FIG. 4, showing the blocks on the bottom of the case. DETAILED DESCRIPTION OF THE INVENTION 10 As shown in FIG. 3, a cord release 10 of the first preferred embodiment of the present invention includes two cases 12 and 14 engaged together by several pairs of blocks and slots on the cases 12, 14 to form a shell. The way of engaging and disengaging the cases 12, 14 is not the main character of the present invention, so we'll not describe in detail here. 15 The cases 12, 14 respectively have a cord fastener 12a, 14a on an inner side thereof Each cord fastener 12a, 14a has two slots 12b, 14b with an open end to receive cords 10a. Each cord fastener 12a, 14a further has walls 12c, 14c projected from bottom edges of the slots 12b, 14b to hold knots of the cords 10a when the cases 12, 14 are engaged, and the cords 10a may easily escape from the slots 12b, 14b of the 20 cord fastener 12a, 14a via the open ends when the cases 12, 14 are disengaged. The case 12 has a first bore 12d and a second bore 12e on a bottom thereof, and the case 14 has a third bore 14d on a bottom. A rope l0b has a knot in one of its end. The un-knotted end of the rope l0b passes through the first bore 12d from within the case 12 out toward the outside of the cord release 10 bottom, and then 25 passes through the bore 14d upwardly, and downwardly through the second bore 12e in 5 sequence out toward the bottom of the cord release 10, so to be used as the pulling rope 10b. As shown in FIG. 4, the shell has a curved guiding slot 17, a half of which is on the case 12 and the other half of which is on the case 14, on a bottom thereof with opposite ends communicated with the first bore 12d and the bore 14d to receive a 5 section of the rope l0b between the first bore 12d and the bore 14d so that the rope l0b will not get entangled with that section. As shown in FIG. 5 and FIG. 6, the cord release 10 has a top opening 16 at a top of the shell. The cords 10a enter the shell through the top opening 16. The top opening 16 is an elliptical opening with a long axis and a short axis. The case 12 has 10 two guiding members 13 on an inner side of a top thereof. The guiding members 13 are projected from an edge 12f of the case 12. Each guiding member 13 has a guiding face 13a with a convex surface facing a center of the top opening 16. The case 14 has two connecting members 15 which are plates on a top of an edge 14e of the case 14. As shown in FIG. 7, each guiding member 13 has a recess 13b, and each connecting 15 member 15 has a protrusion 15a to be engaged with the corresponding recess 13b of the guiding member 13 when the cases 12, 14 are engaged. The shell has a junction plane between edges 12f, 14e of the cases 12, 14 when the cases 12, 14 are engaged, and the guiding members 13 are covering the junction plane. The short axis of the top opening 16 is on the junction plane also. As a result, when the cords 10a are 20 forced to move, they will move to the opposite ends of the long axis of the top opening 16 respectively where it is perpendicular to the junction plane to disengage the cases 12, 14 directly. After the cases 12, 14 are disengaged, the cords 10a will leave the slots 12b, 14b of the cord fasteners 12a, 12b via the open ends then the kid may escape from the cords 10a without any trouble. 25 The first embodiment provides the two guiding members on the same case. 6 As shown in FIG. 8, a cord release of the second preferred embodiment of the present invention has two cases, each of which has a guiding member and a connecting member. The guiding members may guide the cords 10a to the opposite ends of the long axis of the elliptical top opening. FIG. 9 shows the third preferred embodiment 5 of the present invention, in which only one guiding member 13' is provided on the junction of the case. However, it serves the same function as above. As shown in FIG. 10, a cord release 20 of the fourth preferred embodiment of the present invention has three cases 21, 22, and 23 engaged together to form a shell. The same as above, each case 21, 22, and 23 has a guiding member 24 with a guiding 10 face 14, and the guiding members 24 are located at junctions between the neighboring cases 21, 22, and 23. The guiding members 24 serve the same function as above. Besides, the top opening of the cord release 20 can be round. FIG. 11 shows another structure for facilitating the rope 10b to pass through the bore 12e. It provides blocks 12g and 14f on a bottom of each case 12, 14. The 15 blocks 12g and 14f are located at opposite sides of the second bore 12e. A section 10c of the rope l0b between the first bore and the bore crosses over the blocks 12g and 14f so that the rope l0b may pass through the second bore 12e easily. The description above is only a few preferred embodiments of the present invention and the equivalence of the present invention is still in the scope of claim 20 construction of the present invention. 7