JP3027697B2 - High frequency coil - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency coil structure in which a drum core is mounted on a base on which a plurality of terminals are implanted and mounted on a circuit board or the like.

[0002]

2. Description of the Related Art FIG. 4 is a top view of a conventional high-frequency coil with a case and a cap core removed, and FIG. 5 is a partial sectional side view of the conventional high-frequency coil. In the conventional high-frequency coil, a plurality of terminals 42 are provided on opposing side surfaces of a base 41 made of synthetic resin. The terminal 42 is made of a plate-shaped metal piece, and has one end embedded in the base 41 and the other end drawn out from the side surface of the base 41. A storage section 43 is provided on the upper surface of the base 41. A chip capacitor 44 is housed in the housing 43, and an electrode 45 of the chip capacitor is connected to a terminal exposed on the bottom surface of the housing 43. The drum core 46 is bonded to the center of the upper surface of the base 41. The drum core 46 is
An upper flange 47 is formed at one end of the shaft, and a lower flange 48 is formed at the other end of the shaft. A groove 49 is formed between the upper flange 47 and the lower flange 48. And the groove 49 of the drum core 46
The bottom surface of the lower flange 48 of the drum core 46 is adhered to the base 41 with an adhesive or the like. Coil 50
Are wired in the horizontal direction, are connected to terminals 42, and are connected by solder or the like. The drum core 46 is covered by the cap core 51 and the case 52. The cap core 51 is made of a bottomed cylindrical ferrite having an open lower side and a closed upper side. The peripheral side surface is screwed into the case 52 and can be moved up and down by rotating.
The case 51 to which the cap core 50 is screwed is
The case ground terminal 53 is made of metal such as copper, and is bent to the bottom surface of the base 41. In this high-frequency coil, the terminal 42 is connected to the conductor pattern of the circuit board.

[0003] This type of high-frequency coil is desired to be reduced in size, and the size is being reduced year by year. When the high-frequency coil formed in this manner is downsized, the thickness of the base 41 is reduced, and the bottom surface of the lower flange 48 of the drum core 46 is close to the electrode 45, the terminal 42, and the case ground terminal 53 of the chip capacitor. Placed. Therefore, the drum core 4
The eddy current loss occurs because the magnetic flux coming out of 6 is blocked by the electrode 45, the terminal 42 and the case ground terminal 53 of the chip capacitor. When the depth H of the cap core 51 is large, when the cap core 51 is lowered to the lowest position, the open end of the cap core 51 contacts the lead of the coil 50,
Disconnection is easy to occur. However, the depth H of the cap core 51
Is shallow, a gap G occurs between the open end of the cap core 51 and the upper surface of the lower flange 48 bonded to the base 41 even if the cap core 51 is lowered to the lowest position. Therefore, when the depth H of the cap core 51 is small, the magnetic flux emitted from the drum core 46 leaks from the gap G. As described above, the conventional high-frequency coil has a problem in that the eddy current loss occurs and the magnetic flux leaks from the gap G, resulting in a decrease in Q, thereby significantly reducing the electrical characteristics of the high-frequency coil. was there.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-frequency coil in which eddy current loss and leakage magnetic flux are reduced to increase Q and electric characteristics are remarkably improved.

[0005]

According to the high frequency coil of the present invention, the drum core has a shaft and three or more flanges, and the flange is formed along the shaft to form a groove between the flanges. The drum core is mounted with the axis perpendicular to the main surface of the base, the coil is wound around a predetermined groove other than the lowermost groove of the drum core, and the cap core covering the drum core is a groove around which the coil of the drum core is wound. The depth is such that it can cover up to the flange below the upper surface, and the open end of the cap core is always located above the lowermost groove of the drum core. Further, in the high-frequency coil of the present invention, the drum core includes a shaft, an upper flange, an intermediate flange, and a lower flange, and forms an upper flange, an intermediate flange, and a lower flange along the axis to form a groove between the respective flanges. And
The lower flange and the base of the drum core are mounted, and the coil is wound only in the groove formed between the upper flange and the intermediate flange of the drum core. And the opening end of the cap core is always positioned above the groove formed between the intermediate flange and the lower flange of the drum core. Furthermore, the groove formed between the upper flange and the intermediate flange and the groove formed between the lower flange and the intermediate flange have the same width or different widths.

[0006]

The high-frequency coil of the present invention covers the drum core, in which the coil is wound in a predetermined groove other than the groove formed between the lower flange and the intermediate flange, with the cap core, so that the magnetic circuit has: It is formed on the upper collar, middle collar, and cap core.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A high frequency coil according to an embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a top view showing a high-frequency coil according to a first embodiment of the present invention, with a case and a cap core removed. FIG. 2 is a partial sectional side view of FIG. 1 and 2, 11 is a base, 12 is a terminal, 13 is a housing, 14 is a chip capacitor, 15 is an electrode of a chip capacitor, and 16 is a drum core. The base 11 is formed in a rectangular shape using a synthetic resin, and has a plurality of terminals 12 drawn out on opposite side surfaces. The terminal 12 is made of a plate-shaped metal piece, and has one end embedded in the base 11 and the other end drawn out from a side surface of the base 11. A storage section 13 is provided on the upper surface of the base 11. The chip capacitor 14 is housed in the housing 13, and the electrode 15 of the chip capacitor is connected to a part of the terminal exposed on the bottom surface of the housing 13.

A drum core 16 made of ferrite is adhered to the center of the upper surface of the base 11. Drum core 16
Is a so-called three-flange, and the upper flange 1
7, the intermediate flange 18 and the lower flange 19 are formed at different intervals. The upper groove 2 is located between the upper flange 17 and the intermediate flange 18.
0 is formed, and a lower groove 21 is formed between the intermediate flange 18 and the lower flange 19. The width of the upper groove 20 is provided wider than the width of the lower groove 21. The drum core 16 has the central axis perpendicular to the main surface of the base, and the bottom surface of the lower flange 19 and the upper surface of the base 11 are bonded. Then, the coil 22 is wound only in the upper groove 20 of the drum core 16. The lead of the coil 22 is pulled out from the upper groove 20, is tied to a predetermined terminal 12, and is connected by solder or the like. Then, the drum core 16 around which the coil 22 is wound is covered with the cap core 23. The cap core 23 is made of a cylindrical ferrite with a bottom and an opening at the lower side and a closed upper side. The peripheral side surface is screwed to the case 24 and can be moved up and down by rotating. Cap core 23
The depth H of the intermediate collar 1 when lowered to the lowest position
8 is completely covered, and the opening end of the cap core 23 is set at a depth above the lower groove 21 of the drum core 16. The case 24 is made of a metal such as copper, and is attached to the base 11 by bending the case ground terminal 25 to the bottom surface of the base 11. The terminal 12 of the high-frequency coil is connected to the conductor pattern of the circuit board.

FIG. 3 is a partially enlarged sectional view showing a second embodiment of the high-frequency coil according to the present invention. In FIG. 3, 31
Denotes a drum core, and 32 denotes a cap core. Note that FIG.
The same parts as in FIG. Drum core 31
Is a so-called four-flange, and the upper flange 3
3. An intermediate flange 34, 35 and a lower flange 36 are formed. And, between the upper collar 33 and the intermediate collar 34, the intermediate collar 34 and the intermediate collar 35
Grooves 37A, 3G between the middle flange 35 and the lower flange 36, respectively.
7B and 37C are formed. The width of the groove 37C formed between the intermediate flange 35 and the lower flange 36 is the same as that of the other grooves 37A, 3A.
The width is smaller than the width of 7B. This drum core 31
The center axis is perpendicular to the main surface of the base, and the bottom surface of the lower flange 36 and the upper surface of the base 11 are bonded. Then, the coil 38 has a groove 37 formed between the upper flange 33 and the intermediate flange 34.
A, the coil 39 is wound around the groove 37B formed between the intermediate flange 34 and the intermediate flange 35. When the depth of the cap core 32 covering the drum core 31 is lowered to the lowest position, the intermediate flange 35 is completely covered, and the open end of the cap core 32 is positioned between the intermediate flange 35 and the lower flange 36 of the drum core 31. The depth is set at a position above the groove 37C formed at the bottom.

The high-frequency coil 4 formed as described above
Q at 50 KHz is about 110. A conventional high-frequency coil having a coil having the same inductance value and the same capacitance value as the high-frequency coil and having the same material as the components shown in FIG.
Since Q at Hz is about 55, Q is significantly improved. This is because a magnetic circuit is formed in the upper flange, the intermediate flange, and the cap core, and no magnetic flux flows through the lower flange, so that eddy current loss can be reduced. Also, when the cap core is lowered to the bottom, the open end of the cap core covers the intermediate flange below the groove where the coil is wound, forming a completely closed magnetic path, so that the leakage magnetic flux can be reduced. is there.

As described above, the embodiments of the high-frequency coil according to the present invention have been described, but the present invention is not limited to these embodiments. For example, in the drum core, the upper flange, the intermediate flange, and the lower flange may be formed at equal intervals along the axis, and the width of the groove formed between the respective flanges may be equal. In that case, the productivity is improved because the directionality of the drum core is lost. Also,
The terminal may be extended from the bottom surface of the base. Further, in the case of a drum core having a plurality of intermediate flanges, the coil may be wound over a plurality of grooves.

[0012]

As described above, in the high-frequency coil according to the present invention, the drum core has a shaft and three or more flanges, and three or more flanges are formed along the shaft to form a groove between each flange. The drum core is mounted so that the center axis of the drum core is perpendicular to the main surface of the base, a coil is wound around a predetermined groove other than the lowermost groove of the drum core, and the drum core is covered with a cap core. As a result, eddy current loss and leakage magnetic flux can be reduced, Q can be increased, and electrical characteristics can be significantly improved. Further, since the open end of the cap core is always above the lowermost groove of the drum core, the lead of the coil wound around the drum core does not break.

[Brief description of the drawings]

FIG. 1 is a top view showing a high-frequency coil according to a first embodiment of the present invention, with a case and a cap core removed.

FIG. 2 is a partial cross-sectional side view of FIG.

FIG. 3 is a partially enlarged sectional view showing a second embodiment of the high-frequency coil according to the present invention.

FIG. 4 is a top view of a conventional high-frequency coil.

FIG. 5 is a partial cross-sectional side view of a conventional high-frequency coil.

[Explanation of symbols]

 11 Base 12 Terminal 13 Housing 14 Chip Capacitor 15 Chip Capacitor Electrode 16 Drum Core

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01F 17/04 H01F 21/06

Claims (9)

(57) [Claims] 1. A high-frequency coil in which a plurality of terminals are implanted on a base and a drum core for winding the coil is mounted on a main surface of the base, the drum core including a shaft and a plurality of flanges,
The plurality of flanges are formed along the axis to form a groove between the flanges, and the drum core is mounted with the center axis of the drum core perpendicular to the main surface of the base. A coil is wound around a predetermined groove other than the lower groove, and the drum core is
Covered with a cap core, wherein the cap core is
Can cover up to the collar under the groove where the coil is wound
And the open end is always at the bottom of the drum core.
A high-frequency coil, which is located at a position above the groove . 2. The high-frequency coil according to claim 1, wherein the plurality of flanges of the drum core are formed at equal intervals along the axis. 3. The high-frequency coil according to claim 1, wherein the plurality of flanges of the drum core are formed at different intervals along the axis. 4. A high-frequency coil having a plurality of terminals planted on a base and a drum core for winding a coil mounted on a main surface of the base, wherein the drum core includes a shaft, an upper flange, an intermediate flange, and a lower flange. The upper flange, the intermediate flange, and the lower flange are formed along the axis to form a groove between the respective flanges. The lower flange of the drum core is mounted on a base, and the upper flange of the drum core is only a coil wound around a groove formed between the intermediate flange, said Dora
The core is covered with a cap core, and the cap core is
It has a depth that can cover up to the intermediate collar of the ram core,
Opening end is always formed between the intermediate flange and the lower flange of the drum core.
A high-frequency coil which is located at a position above the formed groove . 5. The high-frequency coil according to claim 4, wherein the two grooves of the drum core have the same width. 6. The high frequency coil according to claim 4, wherein the two grooves of the drum core have different widths. 7. A high-frequency coil having a plurality of terminals planted on a base and a drum core for winding a coil on a main surface of the base, wherein the drum core comprises a shaft, an upper flange, a lower flange, and a plurality of intermediate flanges. The upper flange, the intermediate flange, and the lower flange are formed along the axis to form a groove between the respective flanges. The lower flange of the drum core is mounted on the base, The coil is wound around a predetermined groove other than the groove formed between the flange and the intermediate flange, and the drum core is covered with a cap core.
The cap core should cover up to the bottom intermediate flange of the drum core.
And the open end is always the drum core.
Above the groove formed between the lower collar and the intermediate collar.
Frequency coil, characterized in that that. 8. The high-frequency coil according to claim 7, wherein the plurality of grooves of the drum core have the same width. 9. The high-frequency coil according to claim 7, wherein the plurality of grooves of the drum core have different widths.