JPH1188021A - Coil structure and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a lightweight coil structure to make an antenna, etc., light in weight and hardly damage. SOLUTION: A coil 14 which is made by helically winding a metal wire with equal distance in equal outer diameter is unified with a hollow cap 12 made of an insulating material such as the synthetic resin, etc., on its inner surface and with almost half outer section of the coil 14 buried in the cap 12. Thus, a coil element (coil structure) 10 is obtained. The element 10 has a cavity 16 and accordingly is light in weight. Then the element 10 is pressed into a recess groove 20 of a metallic element stage 18 from its upper part, and an upper part 22 of the outer circumference of the stage 18 is caulked toward its center from the outside. Thus, the lower edge of the coil 14 is pressed to the inner circumference 24 of the groove 20 and connected electrically to the stage 18. As a result, the coil 14 is used as a helical antenna.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coil structure used for an antenna or the like of a portable radio device and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, portable wireless devices such as portable telephones and personal handy phone systems (PHS) have been put into practical use.
Various antennas are used in these portable wireless devices. An example of such an antenna is disclosed in
Japanese Patent Application Laid-Open No. 99404 and Japanese Unexamined Patent Application Publication No. Hei 8-32332. These have a coil (helical) insulated from the rod antenna at the tip of the rod antenna
Attach the antenna and push it into the housing of the wireless device during standby, and the coil antenna is connected to the power supply member provided at the top of the housing to function as an antenna. Use it to function as

A conventional coil structure will be described with reference to the drawings, taking the antenna of such a portable radio as an example. FIG. 13 shows a conventional Japanese Patent Publication No.
FIG. 3 is a cross-sectional view of an antenna of a portable wireless device disclosed in JP-A-32332. The antenna shown in FIG. 13 is a rod antenna 11 in which a tube 120 is coated on a feeding member 112.
The rod antenna 110 is provided with a stopper 122 at the lower end, and a bobbin 128 around which the coil antenna 114 is wound at the tip. Put the cap 130 on the bobbin 128 and
A power supply ring 132 that is elastically deformable in the radial direction is held by a supporting concave groove 130a provided on the inner periphery of the lower end of the power supply ring 30. The lower ends of the coil antennas 114 are electrically connected to the feeding ring 132, and these are insulated from the rod antenna 110. At the time of pulling out, as shown in FIG.
2, the lower end of the rod antenna 110 is
2 and the power supply ring 132 is inserted into the fitting groove 112 of the power supply member 112 at the time of storage, as shown in FIG.
a, the lower end of the coil antenna 114 is electrically connected to the power supply member 112. In FIG. 13, 124 is a cabinet, and 126 is a fixing member for fixing the power supply member 112 to the cabinet 124.

[0004]

In the configuration shown in FIG. 13, a coil antenna 114 is wound around a bobbin 128,
If the conventional coil structure is covered with the cap 130, a molded product or the like is used for the bobbin 128, so that the conventional coil structure has a problem that the weight becomes heavy. Therefore, for example, in the case of the antenna as shown in FIG. 13, the weight of the portable wireless device is increased, and when the antenna is extended and shaken violently while being carried, the coil portion at the tip of the rod antenna 110 is not Swinging, unpleasant vibrations were transmitted to the user, and the coil portion was easily damaged by hitting another object.

SUMMARY OF THE INVENTION An object of the present invention is to provide a lightweight coil structure for realizing an antenna or the like which is light and hard to be damaged, and a method for manufacturing the same.

[0006]

According to a first aspect of the present invention, there is provided a coil structure comprising: a coil in which metal wires are wound in a helical shape with equal intervals and an equal outer diameter; And a cap integrated with the coil by burying a portion corresponding to the outside at a certain depth. With this configuration, the weight can be reduced because the inside is hollow. When used as a helical antenna by being attached to the tip of a rod antenna of a portable wireless device, it is hardly damaged by vibration and high-frequency characteristics can be improved.

According to a second aspect of the present invention, there is provided a coil structure in which metal wires are wound in a helical shape in which metal wires are equally spaced and the outer diameter is gradually or gradually increased from the starting end to the end, and the inner surface of the coil is covered with the outer surface. And a cap integrated with the coil by burying a portion of the metal wire corresponding to the outside of the coil at a certain depth. With this configuration, the weight can be reduced because the inside is hollow. When used as a helical antenna by attaching to the end of a rod antenna of a portable wireless device, it is difficult to be damaged by vibration, high frequency characteristics can be improved, and the outer diameter of the coil is gradually or gradually increased from the beginning to the end Therefore, the performance as an antenna can be improved.

According to a third aspect of the present invention, there is provided a coil structure.
Or the coil structure according to 2, wherein the cap is the first
A second coil having a metal wire wound in a helical shape and a second resin portion covering the second coil are each provided at least one outside of the first resin portion. It is characterized by having been provided. With this configuration, it is possible to realize a light weight double or more coil structure.

A coil structure according to a fourth aspect of the present invention is the coil structure according to the first, second or third aspect, wherein the coil is bent in a radial direction near a start end thereof and is bent in an axial direction at a front end thereof as a center. It is characterized by having. Thereby, at the time of manufacturing, a metal wire to be a coil can be wound to an accurate dimension, and a coil structure that can properly exhibit the characteristics of the coil can be realized.

According to a fifth aspect of the present invention, in the coil structure according to the first, second or third aspect, the coil is provided with a hooking projection on an inner peripheral side of a starting end thereof. Thereby, at the time of manufacturing, a metal wire to be a coil can be wound to an accurate dimension, and a coil structure that can properly exhibit the characteristics of the coil can be realized.

According to a sixth aspect of the present invention, there is provided a method of manufacturing a coil structure, wherein a helical groove having a constant depth and equal intervals is provided on an outer peripheral surface of a cylindrical core mold having a uniform outer diameter. A metal wire mounting step of winding a metal wire as a coil in the groove, and installing a core mold around which the metal wire is wound such that at least the coil end side of the core mold projects outside the outer frame mold; An injection molding step of injecting the synthetic resin into the space between the frame mold and the core mold, and then cooling to form a cap made of synthetic resin and integrated with the coil, and after the injection molding step By rotating the core mold, the helical groove of the core mold is slid with respect to the metal wire of the coil to release the core mold, and then the mold removal for removing the outer frame mold is performed. Process.

According to this manufacturing method, the coil structure according to the first aspect can be easily manufactured. According to a seventh aspect of the present invention, in the method for manufacturing a coil structure, the outer peripheral surface of the cylindrical core mold having a diameter whose outer shape gradually increases or increases stepwise from the coil start end side to the coil end side has a constant depth. Providing a helical groove at equal intervals, a metal wire mounting step of winding a metal wire as a coil in this groove, and mounting the metal core wound around the metal core at least at the coil end side of the outer frame die. Installed so as to protrude outside, inject the synthetic resin into the space between the outer frame mold and the core mold, and then cool to form a cap made of synthetic resin and integrated with the coil After the injection molding step and the injection molding step, the core mold is rotated to slide the helical groove of the core mold with respect to the metal wire of the coil to release the core mold, and thereafter, Removing the outer frame mold, including the mold removal process That.

According to this manufacturing method, the coil structure according to claim 2 can be easily manufactured. In the method for manufacturing a coil structure according to claim 8, in the method for manufacturing a coil structure according to claim 6 or 7, the cap formed in the injection molding step becomes the first resin portion, and after the injection molding step, The step of forming a second coil by winding a metal wire around the outer surface of the first resin part in a helical manner, and the step of forming the second resin part covering the second coil by injection molding are each performed in one step. It is characterized in that the process is performed more than once, and then the mold removing process is performed.

According to this manufacturing method, the coil structure according to the third aspect can be easily manufactured. A method of manufacturing a coil structure according to a ninth aspect is characterized in that, in the method of manufacturing a coil structure according to the sixth, seventh or eighth aspect, the metal wire is made of a plastic material.

According to a tenth aspect of the present invention, in the method of manufacturing a coil structure according to the sixth, seventh or eighth aspect, the metal wire mounting step includes the step of mounting the core mold in the radial direction and the axial direction. Among them, a winding jig having an outer shape reduced at least in the radial direction and having a helical groove at the same interval or a small interval as the helical groove of the core mold is prepared. After the metal wire is wound, the winding jig is rotated to remove the coil-shaped metal wire from the winding jig, and then the core metal is rotated while rotating the core mold with respect to the coil-shaped metal wire. A metal wire is mounted in the helical groove of the mold.

According to a eleventh aspect of the present invention, in the method of manufacturing a coil structure according to the sixth, seventh or eighth aspect, at least the starting end of the metal wire serving as the coil is fixed to the core mold. A metal wire fixing means is provided, and the metal wire is fixed by the metal wire fixing means from the time of mounting the metal wire to the core mold until the end of the injection molding process.

According to a twelfth aspect of the present invention, in the method for manufacturing a coil structure according to the eleventh aspect, the metal wire fixing means is attached to the middle core mold from the inside to the outside as the metal wire fixing means. A pressing portion capable of pressing the starting end of the metal wire wound around the helical groove of the core mold and holding the metal wire with the surface of the helical groove is provided, and the pressing portion terminates the injection molding process It can be stored in the core mold later.

According to a thirteenth aspect of the present invention, there is provided a method of manufacturing a coil structure according to the eleventh aspect, wherein the metal wire fixing means is connected to the core mold continuously from the helical groove. A groove extending toward the center from the end face on the coil start end side of the core mold, a hole at the center of the end face that is continuous with the groove extending toward the center, and a direction in which the helical groove extends from the bottom of the groove toward the center. And a first bent portion which is formed in a metal wire to be a coil and whose leading end is bent in a radial direction of the coil and is mounted in a groove directed toward the center of the core mold. And a second bent portion bent so that the tip of the first bent portion is inserted into a hole in the center of the end face of the coil start end side of the core mold. .

According to a fourteenth aspect of the present invention, there is provided the coil structure manufacturing method according to the eleventh aspect, wherein the metal wire fixing means is provided with a hole at the center of the end face of the coil start end of the core mold. And a first bent portion of the metal wire to be a coil, the first end of which is bent in the radial direction of the coil and which is provided on the end surface of the middle core die on the coil start end side; A second bent portion is provided which is bent so that the tip of the bent portion is inserted into a hole in the center of the end face of the middle core mold on the coil starting end side.

According to the manufacturing method of the ninth to fourteenth aspects, it is possible to prevent the coil from being lifted from the core mold due to the springback, and to easily mount the metal wire to be the coil in close contact with the core mold. It is possible to efficiently manufacture a coil structure that can obtain a proper coil size and properly exhibit its characteristics.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A coil structure and a method of manufacturing the same according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view of an antenna using a coil structure according to a first embodiment of the present invention.

In FIG. 1, a coil element 10, which is a coil structure, includes a hollow cap 12 formed of an insulator such as a synthetic resin and a metal such as a copper wire having a circular or special case having a rectangular cross section. A coil 14 in which wires are wound in a helical shape with an equal interval and an equal outer diameter is integrally formed so that the outer periphery of substantially half the outside of the cross section is buried in the cap 12. The inside of the cap 12 and the coil 14 is a cavity 16.

In order to use the coil element 10 as an antenna of a portable wireless device, the coil element 10 is press-fitted into the concave groove 20 of the metal element base 18 from above, and the upper part 22 of the outer periphery of the element base 20 is externally mounted. By swaging in the direction of the arrow toward the center, the coil 14
Is pressed into contact with the inner periphery 24 of the groove 20 to be electrically connected to the element base 18.

The contact portion 2 extending below the element base 18
6 is formed integrally with a metal rod antenna 30 covering the tube 28 by a holding portion 32 made of synthetic resin, and is insulated from the rod antenna 30.
The lower part of the rod antenna 30 is attached to the cabinet 34, but after passing through a connecting member 38 having a slotted lower part 36, the lower part is swaged by a metal stopper 42 having a retaining part 40. 42 are electrically connected. Connection member 38
Is connected to an antenna terminal of a transmitting / receiving circuit of a portable wireless device (not shown).

With respect to the antenna thus configured,
The operation will be described. The state of FIG.
Is extended upward from the cabinet 34, and the lower end of the rod antenna 30 is provided with a stopper 40 and a connecting member 38.
It is connected to the antenna terminal of the transmission / reception circuit of the portable wireless device via the slit 36. When the coil element 10 is pushed down, the stopper 40 separates from the slit 36 of the connecting member 38 and the rod antenna 30 moves the connecting member 38.
When the contact portion 26 of the element base 18 is further pressed down to the end, the contact portion 26
The coil is electrically connected to the slit, and the lower end of the coil is connected to an antenna terminal of a transmitting / receiving circuit of the portable wireless device.

The method of fixing the coil element 10 to the element table 18 is not limited to that shown in FIG. 1, but may be, for example, as shown in FIGS. 2 (a) and 2 (b). That is, FIG.
FIG. 2 is a cross-sectional view showing a method of fixing the coil element 10 to the element base 18 other than FIG. 1. As shown in FIG. 2A, a skirt that covers the lower end of the cap 12 a from above the outer periphery 22 a of the element base 18 a. A portion 12b may be provided, and the skirt portion 12b may be adhered to the outer periphery 22a. If the cap 12c is formed of an elastomer or the like as shown in FIG. 2B, the lower end 12d wraps inward. Even if it is a simple shape, it can be fitted into the outer periphery 22b of the element base 18b while pushing and opening the lower end 12d.

Next, a method of manufacturing the coil element 10 will be described with reference to FIGS. FIG. 3 is an external perspective view of the core mold in the manufacturing process of the coil element 10,
FIG. 4 is a cross-sectional view of a state in which the coil is wound around the core mold in the manufacturing process of the coil element 10 and is set in an outer frame mold (upper / lower mold). First, as shown in FIG. 3, a helical groove 52 having an equal depth is formed on the outer periphery of a metal-made, uniform cylindrical core mold 50 having a uniform thickness. The cross section of the groove 52 is adapted to the shape of the metal wire used for the coil 14. When the cross section of the metal wire is circular, the cross section is a semicircle having a radius slightly larger than the radius, and the depths are all the same. It is. And the helical pitch must be constant.

Next, the metal wire forming the coil 14 is wound around the helical groove 52 of the core mold 50. When the metal wire is wound around the groove 52 of the core mold 50, the metal wire is wound. If the metal wire is lifted out of the helical groove 52 when the winding is completed by the springback, the correct dimensions of the coil 14 cannot be obtained, and the characteristics of the coil cannot be exhibited.

Therefore, one method is to use a soft plastic wire without springback, for example, annealed copper wire as the metal wire of the coil 14.
The metal wire can be wound in a state in which the metal wire is in close contact with the groove 52 of the core mold 50. As another method, in consideration of springback, the core mold 50 has an outer shape that is reduced in at least the radial direction in the radial direction and the axial direction, and has the same interval as the helical groove of the core mold 50. Alternatively, a winding jig (not shown) provided with helical grooves at small intervals is prepared, a metal wire is wound around the jig, and the winding jig is turned clockwise as viewed from above to form a coil. The winding jig is extracted from the metal wire thus formed, and the coiled metal wire is inserted into the helical groove 52 while rotating the counter-clockwise direction when the core mold 50 is viewed from above, thereby forming the coil 14. . The winding jig may have a smaller diameter than the core mold 50, or may have a smaller diameter and a smaller interval between the grooves. However, the number of turns must be increased accordingly.

Next, as shown in FIG.
The state where the coil 14 is inserted into the groove 52 is inserted and installed between the upper mold 54 and the lower mold 56. In this state, when the molten synthetic resin is injected from the gate 58 provided in the lower mold 56, the cavity 60 is filled with the synthetic resin, which becomes the cap 12. After cooling, the core mold 5
0, the helical groove 52 of the core mold 50 slides along the coil 14 remaining in the molded product similarly to the screw, and the core mold 50 is rotated. Is pushed out in the direction of the arrow in FIG. 4 and is separated from the upper mold 54 and the lower mold 56. Thereafter, the upper mold 54 and the lower mold 56 are opened, the molded product is taken out, and the gate is finished.
Can be obtained. The location where the core mold 50 is located is the cavity 16.

As described above, according to the first embodiment,
The coil element 10, which is a coil structure, includes a coil 14 in which metal wires are wound in a helical shape at equal intervals and an equal outer diameter,
The outside of the coil 14 is covered, and a portion of the metal wire corresponding to the outside of the coil 14 is buried at a certain depth on the inner surface to form the coil 14.
And the integrated cap 12, and the weight can be reduced because the inside is hollow. In addition, when used as a helical antenna by being attached to the tip of a rod antenna 30 of a portable wireless device as shown in FIG. 1, it is difficult to be damaged by vibration, high-frequency characteristics can be improved, and the weight of the portable wireless device can be reduced. .

Further, the coil 14 is manufactured by the above-described manufacturing method.
Prevents the metal wire serving as the coil 14 from being tightly attached to the core mold 50, and provides a coil having accurate coil dimensions and exhibiting its characteristics correctly. The element 10 can be easily and efficiently manufactured. The fact that the high-frequency characteristics can be improved as described above when the coil structure according to the present embodiment is used as a helical antenna will be described with reference to FIGS. In FIG. 5, the radiation pattern when the coil element 10 which is the coil structure in the present embodiment is attached to the tip of the rod antenna 30 of the portable wireless device as shown in FIG. 1 and used as a helical antenna is shown in FIG. The measurement data is shown in (b). FIG. 6 shows a radiation pattern when the conventional coil structure is used as a helical antenna as shown in FIG. 13, and FIG. 6B shows measured data. Note that in each case, a 1.5 GHz band digital mobile phone was used, the radiation pattern was at 1489 MHz, and the radiation efficiency η indicates the ratio of λ / 2 dipole antenna.

In the case of FIG. 6, the radiation efficiency η is −8.33 d.
B, whereas the radiation efficiency η in the case of FIG.
92 dB, which is 1.41 dB higher than the case of FIG. Therefore, the resin (bobbin 12
The coil structure having the cavity 16 therein as in the present embodiment can improve the high frequency characteristics of the helical antenna, as compared with the coil structure filled with 8). In the related art, it is considered that reactive energy concentrated in the coil causes heat loss due to dielectric loss of the resin filled therein.

[Second Embodiment] In the second embodiment, a method for manufacturing the coil element 10 as a coil structure other than the method described in the first embodiment will be described. FIG. 7 shows a core mold 62 used in the second embodiment of the present invention.
Is a perspective view at the time of mounting, and (b) is a side sectional view at that time.

Helical groove 64 provided in the core mold 62
Are the same as the grooves 52 in the first embodiment. The slider 66 includes a pressing portion 7 that presses the slope 68 and the coil 14.
0, and is slidable in the space 72 inside the core mold 62 inward and outward of the core mold 62, that is, left and right in FIG. 7B. 6
2, that is, rightward in FIG. 7B. The action rod 76 has a slope 78 facing the slope 68 of the slider 66.

A method for manufacturing the coil element 10 using the core mold 62 will be described. Normally, the slider 66 is urged rightward in FIG. 7B, and occupies a position where the pressing portion 70 bites into the groove 64 above the groove 64. When a metal wire serving as the coil 14 is wound here, the metal wire is sandwiched and held between the groove 64 and the pressing portion 70 of the slider 66. If such sliders 66 are located at two locations above and below the core mold 62, the coil
Is held and springback can be prevented, but only one location may be located above, in which case the lower end of the coil 14 is located outside the mold, so it can be wrapped around another one or pulled and pulled. Can be held.

In this state, as in the first embodiment, the middle core mold 50 is placed in the upper mold 54 and the lower mold 56 in FIG.
After the resin is cooled and the resin is cooled, first, the working rod 76 is pushed upward in FIG. 7B, and the slope 78 pushes the slope 68 of the slider 66. The slider 66 slides leftward in FIG. 7B against the urging force of the spring 74, and the pressing portion 68 of the slider 66 stops pressing the coil 14. In this state, as in the first embodiment, if the core mold 62 is rotated clockwise as viewed from above, the helical groove 64 of the core mold 62 is formed in the molded product. After sliding along the remaining coil 14, the core mold 62 is pushed downward in FIG. 4 and separates from the upper mold 54 and the lower mold 56. Thereafter, the upper mold 54 and the lower mold 56 are opened, the molded product is taken out, and the gate is finished, whereby the coil element 10 can be obtained.

According to the second embodiment, the coil 14 is prevented from floating from the core mold 62 due to springback, and the metal wire to be the coil 14 is connected to the core mold 6.
This makes it possible to easily and efficiently manufacture the light-weight coil element 10 capable of obtaining accurate coil dimensions and exhibiting its characteristics correctly. [Third Embodiment] In a third embodiment, a method for manufacturing a coil element as a coil structure will be described.
Methods other than those described in the first and second embodiments will be described.

FIG. 8 shows a core mold and a coil used in the third embodiment, (a) is a perspective view of the core mold,
(B) is a drawing of the end of the coil attached to the core mold,
(C) is a plan view of a state where a coil is mounted on the core mold, and (d) is a perspective view thereof. The core mold 80 used in the third embodiment has a helical groove 52 shown in FIG.
A helical groove 81 machined in the same manner as that described above is provided, but differs from FIG. 3 in that the structure is adapted to a coil 82 machined as shown in FIG. 8B. The coil 82 has, at its upper end, a portion (first bent portion) 83 bent at a right angle toward the center and a portion (second bent portion) 84 bent at a right angle downward at the center in advance. Process it. In accordance with this, the core mold 80 has a groove 85 that extends from the part where the helical groove 81 reaches the upper end to the center of the upper end surface of the core mold 80 in a continuous direction with the helical groove 81, A gentle slope 8 extending from the bottom of the groove 85 along the extension direction of the groove 81
6 and a shallow hole 87 in which the distal end portion 84 of the metal wire of the coil 82 enters downward at the center continuously from the groove 85.

A method for manufacturing a coil element using the core mold 80 will be described. The tip portion 84 of the coil 82 is inserted into the center hole 87 of the core mold 80, the bent portion 83 toward the center is applied to the wall of the groove 85, and the coil is wound along the helical groove 81. Since the lower end is outside the mold, it may be fixed by any method as in the second embodiment.

In the same manner as in the first embodiment, the core mold 80 having the coil 82 mounted thereon is replaced with the core mold 50 in FIG. When the molten synthetic resin is injected from the gate 58 in this state, the cavity 60 is filled with the synthetic resin, and after cooling, if the middle core mold 80 is rotated clockwise as viewed from above, Like the screw, the helical groove 81 of the core mold 80 slides along the coil 82 remaining in the molded product, and the core mold 80 is about to be pushed in the direction of the arrow in FIG. At this time, after the wall of the groove 85 of the core mold 80 is separated from the portion 83 of the coil 82 bent at a right angle, the gentle slope 86 slides on the portion 83 of the coil 82 bent at a right angle. The core mold 80 moves downward, and at the same time, the tip portion 84 of the coil 82 is directed straight downward, so that it slides in the hole 87 in accordance with the rotation of the core mold 80 and slips out. The core mold 80 includes an upper mold 54 and a lower mold 56.
Leave from inside. Thereafter, the upper mold 54 and the lower mold 56 are opened, and the molded product is taken out and subjected to gate finishing, whereby a coil element having the coil 82 therein can be obtained. Although the coil 82 has a different upper end structure from the coil 14, there is almost no problem in practical use.

According to the third embodiment, the coil 82 is prevented from floating from the core mold 80 due to springback, and the metal wire to be the coil 82 is removed from the core mold 8.
This makes it possible to easily and efficiently manufacture a lightweight coil element capable of obtaining accurate coil dimensions and exhibiting its characteristics correctly. In addition,
In the above embodiment, in addition to the helical groove 81, a groove 85 heading toward the center on the upper end surface, a gentle slope 86, and a shallow hole 87 into which the distal end portion 84 of the metal wire enters, in the middle core mold 80.
However, if the helical groove 81 and the shallow hole 87 into which the distal end portion 84 of the metal wire is provided without providing the groove 85 and the gentle slope 86 facing the upper end surface toward the center, Is wound around the coil 82 which has been subjected to the terminal processing, thereby forming the core mold 8 by springback of the coil 82.
Floating from zero can be prevented. In this case, the processing of the core mold requires only the center hole 87 in addition to the helical groove 81, and the processing of the core mold is easier than that of the core mold 80 in FIG. Using the middle core mold 80 of 8 makes the coil 82 more fixed.

[Fourth Embodiment] In a fourth embodiment, a method other than those described in the first to third embodiments will be described for a method of manufacturing a coil element as a coil structure. . 9A and 9B show a core mold and a coil used in the fourth embodiment. FIG. 9A is a perspective view of the core mold, and FIG. 9B is a perspective view showing a state where the coil is mounted on the core mold. FIG.

The core mold 50 in FIG. 9 is the same as that of the first embodiment. The metal wire of the coil 88 is crushed at its upper end to be thicker to form a hooking projection 89. The squashed projection 89 is caught on the upper end of the helical groove 52 and does not move even by the winding force in the direction of the arrow in FIG. 9B. Since the lower end of the coil 88 is outside the mold, it may be fixed by any method.
The core mold 50 around which the coil 88 is wound is mounted in the upper mold 54 and the lower mold 56 and injection molded in the same manner as in the first embodiment. When the top 50 is rotated clockwise as viewed from above, the projection 89 at the upper end portion comes out of the groove 52 and the core mold 50 is separated from the coil 88 without any trouble. After that, the upper mold 54 and the lower mold 56
When the gate is finished by taking out the molded product by opening the coil 88, a coil element having the coil 88 inside can be obtained.

According to the fourth embodiment, the coil 88 is prevented from rising from the core mold 50 due to springback, and the metal wire to be the coil 88 is connected to the core mold 5.
This makes it possible to easily and efficiently manufacture a lightweight coil element capable of obtaining accurate coil dimensions and exhibiting its characteristics correctly. In addition,
In each of the above embodiments, the case where the outer shape of the coil has the same outer diameter over the entire length has been described.However, some helical antennas have the above-described configuration for the purpose of improving the side lobe level and the axial ratio, or increasing the bandwidth. A modified version of the above is used. When the manufacturing method described in each of the above embodiments is applied, processing can be performed as long as the outer diameter decreases upward, and an example of such a shape is shown in FIG.

In FIG. 10, (a) is a cone-shaped coil 90 whose outer diameter decreases linearly from below to above. (B) A coil-shaped coil 91
In this case, the outer diameter becomes smaller in a hanging shape as it goes upward. The outer diameter of the two-stage tapered coil 92 in (c) becomes smaller in two stages as it goes upward.
FIG. 11 is an external perspective view showing an example of the core mold 93 when the coil structure having the cone-shaped coil 90 of FIG. 10A is formed. As the diameter becomes linearly smaller, the helical groove 94 also keeps the same pitch while keeping the same depth with respect to the outer diameter.
Can be removed from the coil 90 while rotating.

The concept is the same for other types of deformed coils such as those shown in FIGS. 10B and 10C. The shape of the core mold is gradually or stepwise reduced as its outer diameter goes upward. By employing a configuration in which helical grooves with a constant depth are provided at regular intervals on the outer peripheral surface, the above-described processing method can be applied to these deformed coils, and can contribute to an improvement in performance as an antenna. In other words, the outer shape of the center mold is a cylindrical shape having a diameter that gradually or stepwise increases from the coil start end side to the coil end side, and has a constant depth and a uniform helical shape on its outer peripheral surface. The groove can be manufactured by winding a metal wire as a coil around the groove.

As described above, in the above-described embodiment, the hollow cap and the coil are integrally formed by rotating and removing the core mold from the helical coil after the formation of the hollow cap. Can form a structure,
A light antenna can be realized using this coil structure, and a practical method of how to make the coil adhere to the helical groove of the core mold for that purpose was also shown. is there.

In the above embodiment, the present invention has been described for use in an antenna. However, the present invention is not limited to an antenna, but can be applied to all cases where a hollow coil such as an inductor for a high-frequency circuit, a tuning coil, and a magnetic field sensor can be used. [Fifth Embodiment] FIG. 12 is a process chart showing a method of manufacturing a coil structure according to a fifth embodiment of the present invention.

The coil structure in the present embodiment is a coil element 100 shown in FIG.
A double coil structure having a first coil 102 and a second coil 104, in which a metal wire is wound around the inner surface of the first resin portion 103 of the cavity 106 in a helical shape with equal intervals and an equal outer diameter. Is formed in such a manner that the outer periphery of almost half of the cross section of the coil 102 is buried in the first resin portion 103, and the second wire in which a metal wire is helically wound around the outer surface of the first resin portion 103. A coil 104 is formed, and the second resin portion 10 is formed so as to cover the second coil 104 and the first resin portion 103.
5 are formed. The second coil 104 is formed such that its cross section is buried approximately half by each of the first resin portion 103 and the second resin portion 105.

The thus configured coil element 1
00 will be described. First, as shown in FIG. 12 (a), a metal-made, uniform cylindrical core mold 10 having a uniform thickness.
A helical groove having an equal depth and a constant pitch is formed on the outer periphery of the groove 1. Next, as shown in FIG. 12B, a metal wire forming the first coil 102 is wound around the helical groove of the core mold 101. This state is inserted between the upper mold and the lower mold, and the synthetic resin is injection-molded. Then, the upper mold and the lower mold are removed, thereby obtaining FIG.
A first resin portion 103 having a helical groove on the outside is formed as shown in FIG. The steps so far are performed in the first to fourth embodiments by processing the upper mold and the lower mold so that a helical groove is provided when the first resin portion 103 is molded. The manufacturing method described in the embodiment (excluding the step of removing the core mold) can be applied. Next, FIG.
As shown in (d), a metal wire forming the second coil 104 is wound around a groove outside the first resin portion 103. This state is inserted and installed between the upper mold and the lower mold, and injection molding of synthetic resin is performed to form the second resin portion 105 as shown in FIG. The mold 101 is rotated to be separated, and the upper mold and the lower mold are removed. Core mold 10
1 is the cavity 106.

As a method for preventing the second coil 104 from floating from the first resin portion 103, the same method as that described in the first, third, and fourth embodiments is used. Can be. Also, the first resin part 103 is
It is necessary to use a material having a higher heat-resistant temperature than the second resin portion 105 so as to withstand heat and pressure during molding of the second resin portion 105.
When S is used, PBT (polybutylene terephthalate) or heat-resistant ABS having a higher heat-resistant temperature may be used for the first resin portion 103. The coil structure according to the fifth embodiment can be applied to a two-resonance antenna such as an antenna for a dual-band radio and an antenna for a GSM / PCN dual-band mobile phone, and can also be applied to a high-frequency transformer and a double-tuned coil. In these cases, the characteristics are stabilized because the relative positions of the two coils 102 and 104 are determined via the first resin portion 103.
When used as an antenna, two coils 1
Since the elements 02 and 104 are inductively coupled, either one or both of them may be electrically connected to the element table (see the element table 18 in FIG. 1).

In the fifth embodiment, the shape of the first coil 102 has been described as having the same outer diameter over the entire length. However, similar to the first to fourth embodiments, FIG. The shape shown in FIG. Further, the pitch of the second coil 104 is not particularly limited, may be an unequal pitch, and the outer diameter is not particularly limited over the entire length. For example, the second coil 104 may be formed such that the outer diameter of the first coil 102 decreases from lower to upper, and the outer diameter increases from lower to upper.

In the fifth embodiment, a double coil structure is used. However, the present invention can be similarly applied to a triple or more coil structure. Since the inside is hollow, the weight can be reduced. What can be done is the same as in the first embodiment. In the case of a triple coil structure, in the step shown in FIG. 12, (a), (b), (c), (d), (c),
The steps (c) and (d) may be repeated as in (d) and (e) (however, the dimensions and materials are different), and the same applies to more cases.

[0055]

As described above, the present invention provides the first aspect.
Alternatively, the weight of the coil structure described in 2 can be reduced because the inside is hollow. In addition, when used as a helical antenna by being attached to the tip of a rod antenna of a portable wireless device, it is hardly damaged by vibration, high-frequency characteristics can be improved, and the weight of the portable wireless device can be reduced.

Further, according to the configuration of the third aspect, a double or more coil structure having a light weight can be realized and can be applied to a two-resonance antenna, a high-frequency transformer, a double-tuned coil, and the like. Further, according to the configuration of the fourth or fifth aspect, it is possible to realize a coil structure in which a metal wire to be a coil can be wound to an accurate size during manufacturing, and the characteristics of the coil can be exhibited correctly.

Further, the coil structure according to the first aspect can be easily manufactured by the method for manufacturing a coil structure according to the sixth aspect, and the second aspect according to the method for manufacturing a coil structure according to the seventh aspect. The coil structure according to claim 8 can be easily manufactured, and the coil structure according to claim 3 can be easily manufactured by the method for manufacturing a coil structure according to claim 8.

Further, according to the method for manufacturing a coil structure according to the ninth to fourteenth aspects, it is possible to prevent the coil from being lifted from the core mold due to springback of the coil, to obtain accurate coil dimensions, and to exhibit the characteristics of the coil. Thus, the production of the coil structure can be performed more efficiently.

[Brief description of the drawings]

FIG. 1 is a side sectional view of an antenna using a coil structure according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing another method of fixing the coil element to the element base in the first embodiment of the present invention.

FIG. 3 is an external perspective view of a core mold according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a state in which a coil is wound around a core mold in an outer frame mold (upper / lower mold) according to the first embodiment of the present invention.

FIG. 5 is a view showing a radiation pattern and measurement data when the coil structure according to the first embodiment of the present invention is used as a helical antenna.

FIG. 6 is a diagram showing a radiation pattern and measurement data when a conventional coil structure is used as a helical antenna.

FIG. 7 is a view showing a middle core mold according to a second embodiment of the present invention.

FIG. 8 is a diagram showing a core mold and a coil according to a third embodiment of the present invention.

FIG. 9 is a diagram showing a core mold and a coil according to a fourth embodiment of the present invention.

FIG. 10 is an external perspective view of a coil whose outer diameter changes in the embodiment of the present invention.

FIG. 11 is an external perspective view of a core mold used to form a cone-shaped coil which is an example of FIG.

FIG. 12 is a process chart showing a method for manufacturing a coil structure according to a fifth embodiment of the present invention.

FIG. 13 is a sectional view showing an antenna using a conventional coil structure.

[Explanation of symbols]

Reference Signs List 10 coil element (coil structure) 12 cap 14, 82, 88, 90, 91, 92 coil 16 cavity 18 element base 50, 62, 80, 93 middle core mold 52, 64, 81, 94 helical groove 54 Upper mold (outer frame mold) 56 Lower mold (outer frame mold) 60 Cavity 66 Slider 70 Pressing portion 83 Part bent at right angle toward the center (first bent part) 84 Right angle downward at center (Groove) 85 Groove 86 Slope 87 Hole 89 Hook projection 100 Coil element (coil structure) 101 Middle core mold 102 First coil 103 First resin part 104 Second Coil 105 second resin part 106 cavity

Claims (14)

[Claims] 1. A coil in which a metal wire is wound in a helical shape at an equal interval and an equal outer diameter, and a portion which covers the outside of the coil and has an inner surface corresponding to the outside of the coil of the metal wire at a constant depth. A coil structure comprising a cap embedded and integrated with the coil. 2. A coil formed by helically winding metal wires at regular intervals and having an outer diameter gradually or stepwise increasing from a starting end to a terminating end; and covering the outside of the coil with an inner surface of the coil of the metal wire. And a cap integrated with the coil by burying a portion corresponding to the outside of the coil at a certain depth. 3. A cap comprising a first resin portion, a second coil formed by winding a metal wire in a helical shape on the outside of the first resin portion, and a second coil covering the second coil. The coil structure according to claim 1, wherein at least one resin portion is provided. 4. The coil structure according to claim 1, wherein the coil has a shape bent in the radial direction near the start end and bent in the axial direction at the center at the center. 5. The coil structure according to claim 1, wherein the coil is provided with a projection for hooking on an inner peripheral side of a starting end thereof. 6. A metal wire in which a helical groove having a constant depth and equal intervals is provided on an outer peripheral surface of a cylindrical core mold having a uniform outer diameter, and a metal wire is wound as a coil in this groove. A mounting step, a core mold around which the metal wire is wound is installed such that at least the coil end side of the core mold projects outside the outer frame mold, and the outer frame mold and the middle core mold are mounted. An injection molding step of injecting a synthetic resin into a space between the mold and cooling to form a cap made of the synthetic resin and integrated with the coil; By rotating the helical groove of the core mold relative to the metal wire of the coil, the core mold is released, and then the mold removal for removing the outer frame mold is performed. And a method for manufacturing a coil structure. 7. A helical groove having a constant depth and a constant depth is formed on the outer peripheral surface of a cylindrical core mold having a diameter whose outer shape gradually or stepwise increases from the coil start end side to the coil end side. A metal wire mounting step of winding a metal wire as a coil in the groove, and installing a core mold around which the metal wire is wound so that at least the coil end side of the core core projects outside the outer frame mold. And an injection molding step of injecting a synthetic resin into a space between the outer frame mold and the core mold, and then cooling it to form a cap made of the synthetic resin and integrated with the coil. After this injection molding step, by rotating the core mold, the helical groove of the core mold is slid with respect to the metal wire of the coil to release the core mold. Then, the mold removal for removing the outer frame mold Method for manufacturing a coil structure including a was step. 8. A cap formed in an injection molding step is a first cap.
Forming a second coil by helically winding a metal wire on the outer surface of the first resin portion after the injection molding step, and a second resin covering the second coil. 8. The method for manufacturing a coil structure according to claim 6, wherein the step of forming the part by injection molding is performed at least once, and thereafter, the mold removing step is performed. 9. The method for manufacturing a coil structure according to claim 6, wherein the metal wire is made of a plastic material. 10. The metal wire mounting step has an outer shape obtained by reducing the core mold in at least the radial direction of the radial direction and the axial direction, and has the same interval or smaller as the helical groove of the core mold. A winding jig provided with a helical groove at intervals is prepared, and after winding a metal wire to be a coil around the winding jig, the winding jig is rotated to wind the coil-shaped metal wire into the winding jig. 7. The metal wire is then mounted in the helical groove of the core mold while rotating the core mold with respect to the coil-shaped metal wire. 9. The method for manufacturing a coil structure according to claim 7, 7 or 8. 11. A metal wire fixing means for fixing at least a starting end of a metal wire to be a coil to a core mold, and the metal wire fixing means injects the metal wire from the time of attachment to the core mold. 9. The method for manufacturing a coil structure according to claim 6, wherein the metal wire is fixed until a molding step is completed. 12. As a metal wire fixing means, a core mold is provided.
The metal wire is urged from the inside toward the outer direction and presses the start end of the metal wire wound around the helical groove of the core mold, and the metal wire can be sandwiched between the metal wire and the surface of the helical groove. The method for manufacturing a coil structure according to claim 11, wherein a pressing portion is provided, and the pressing portion can be housed inside the core mold after the end of the injection molding process. 13. A metal wire fixing means comprising: a groove extending from a helical groove of the core mold toward the center of a coil starting end of the core mold toward the center; A hole at the center of the end face that is continuous with the groove, and a gentle slope that is continuous from the bottom of the groove toward the center in the extension direction of the helical groove is provided. Is bent in the radial direction of the coil, and is attached to a groove toward the center of the core mold, and the tip of the first bent part is the core mold. 12. A method for manufacturing a coil structure according to claim 11, wherein a second bent portion is provided so as to be inserted into a hole at the center of the end face on the coil start end side. 14. A metal wire fixing means, wherein a hole is provided in the center of the end face of the coil start end of the core mold, and the start end of the metal wire to be a coil is bent in the radial direction of the coil. A first bent portion provided on the end face of the core mold on the coil starting end side, and a tip of the first bent portion having a hole at the center of the end face of the core mold on the coil starting end side; 12. A method for manufacturing a coil structure according to claim 11, further comprising providing a second bent portion bent so as to be inserted into the coil structure.