US 3783417 A
An inductance coil is disclosed having a core with flanges at both ends thereof. A partition wall is provided at an intermediate part of the core so as to form at least two separate coil winding spaces on the core between the two end flanges and the partition wall. The coil winding spaces are exactly the same width and windings are provided in the winding spaces with exactly the same number of turns.
Claims available in
Description (OCR text may contain errors)
United States Patent [191 Osada et al.
[ Jan. 1,1974
[ INDUCTANCE COIL  Inventors: Hisasi Osada; Tadaharu Akino, both of Tokyo, Japan  Assignee: TDK Electronic Company, Tokyo,
Japan  Filed: Aug. 9, 1972  Appl. No.: 279,072
 Foreign Application Priority Data Jan. 14, 1970 Japan 45/4315  U.S. Cl. 333/70S, 333/29  Int. Cl. H03h 7/32  Field of Search 333/705, 29
 References Cited UNITED STATES PATENTS 2,416,297 2/1947 Finch et a1 333/29 1,456,909 5/1923 Pupin 1,576,459 3/1926 Pierce 333/29 Tawney..........
2,729,795 1/1956 Hoeppner 333/29 2,756,170 7/1956 Smoliar 333/29 2,776,411 1/1957 Anderson 333/29 2,823,354 2/1958 Lubkin 3331705 3,617,949 11/1971 Kameya et a1. 333/29 OTHER PUBLICATIONS Golay, M; J. E., The Ideal Low-Pass Filter in the Form of a Dispersionless Lag Line, Pro. lre, Vol. 34, 1946, pp. 138-144.
Primary Examiner-Rudolph V. Rolinec Assistant Examiner-Wm. l-l. Punter Att0rneyOb10n, Fisher & Spivak  I ABSTRACT 6 Claims, 5 Drawing Figures PATENTEDJM 1 3.783.417
PRIOR ART F|G .5- T 7 4 d INVENTORS HISASI QSADA TADAHARU Ammo BY (9% u ATTORNEYS BACKGROUND OF THE INVENTION 1. Field Of The Invention:
This invention relates. to an inductance coil, and more particularly to an inductance coil for a derived m-type filter.
2. Description Of The Prior Art:
When a delay circuit is constructed by using a derived m-type filter, it has been customary to use an inductance coil with a winding arranged on a cylindrical core, and having a tap taken from the middle portion of the winding. In this type of inductance coil, when used for a derived m-type filter, it is absolutely necessary that the selfinductance between one end of the winding and the tap, and the self-inductance between the other end of the winding and the tap should be equal, and that the mutual-inductance of both parts of the coil should be a constant value. In addition, it is most desirable that identical coils can be fabricated using mass production techniques.
However, when inductance coils of the type described above are produced in large quantities, it is very difficult to produce coils having identical characteristics, and consequently self-inductance and mutualinductance become irregular.
SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a novel and improved inductance coil for a derived m-type filter.
Another object of the present invention is to provide an inductance coil for a derived m-type filter which can be manufactured in large quantities withidentical characteristics.
Still another object of the present invention is to provide an inductance coil for a derived m-type filter which is suitable for use in electroniccomputers, radars, and other devices which require a large number of delay elements with equal delay time.
Yet another object of the invention is to provide an inductance coil for a derived m-type filter wherein flanges provided on a central core produce a-s pecial magnetic field; i
Briefly, these and other objects are attained by producing an inductance coil composed of a cylindrical 'core with a plurality offflanges'mounted on it.
BRIEF DESCRIPTION OF THE DRAWINGS Other objects, features-and many of the attendant advantages of this invention will be appreciated more readily as the same becomes better understood by reference to the following detailed description, when considered in connection with the accompanying Drawings, wherein:
FIG. 1 is a schematicdiagram of a conventional electrical circuit illustrating an m-type filter;
FIG. 2 is a schematic diagram of adelay circuit using m-type filters;
FIG. 3 is a perspective view of a conventional inductance coil of the type which haverbeen used in constructing m-type filters;
FIG. 4 is a perspective view of an inductance coil for m-type filters in accordance with the present invention; and,
FIG. 5 is a cross-sectional view of the inductance coil shown in FIG. 4,- illustrating the dimensions and arrangement of the end flanges, intermediate flange, and core of the present invention.
DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS Referring now to the Drawings, wherein like reference numerals designate identical or corresponding parts throughout the'several views, and more particularly to FIG. 3 thereof, a conventional inductance coil is shown as formed of a cylindrical core 1 made of 'a conventional core material, around which a winding 2 is provided having a tap 3 at the middle thereof. A pair of leads 4 and 5 are provided'at either end of coil 2. This inductance element is usually employed in a derived m-type filter as shown in FIG. 1, which may be used to construct a delay circuit by connecting a plurality of filter elements in series as shown in FIG. 2.
In the inductance coil of FIG. 3, the self-inductance between tap 3 and either end of coil 2 should be equal, and the mutual-inductance of the entire coil should be the same for all coils manufactured. However, it is very difficult to fulfill the above requirements if a conventional cylindrical core is employed. In addition, special attention must be paid as to the number of turns wound on the core, as well as to the position at which the tap is taken.
Reference is now made to FIGS. 4 and 5 of the Drawings in which the inductance coil of the present invention is illustrated. The inductance coil of the present invention comprises a drum core 6 having flanges 7 and 8 at both sides of the core, and an intermediate flange or wall 9 at the center of the core. These flanges and the wall are fabricated on the core by casting or by grinding a round bar. The flanges and the wall may be made integral with drum core 6, or may be made separate from core 6. In the latter case, the flange is designed to be of disk-like shape, and an aperture is provided at the center of the disk. This type of flange is mounted on the core by inserting the core into the center aperture of the flange, and the mounted flanges are then secured on the core by welding or by other conventional means.
The drum core 6 is preferably of cylindrical shape, and has thesame circumference along its entire length.
In the preferred embodiment of thepresent invention, as shown in FIGS. 4 and 5, flanges 7 and 8 are provided at the both ends of the cylindrical drum core 6, and the intermediate part of the core 6 between the end flanges 7 and 8 has an intermediate flange 9 which is substantially the same shape as the end flanges 7 and 8 in order to divide the core 6 into at least two coil winding regions. However, it should be understood that the number of intermediate flanges placed between the end flanges is not limited, and a plurality of intermediate flanges may be arranged along the core so as to form a number of coil winding regions.
In the present invention, it should be noted that the intermediate flange 9 is placed exactly in the middle of the core defined by end flanges 7 and 8 in order to form coil winding regions having exactly the same width at both sides of the intermediate flange 9.
As shown in FIG. 4, a pair of windings I0 and l l are respectively positioned in the coil winding regions defined by flanges 7, 9 and 8, 9. These windings are connected in series at the intermediate flange 9 of the inductance elment. In practice, the winding coils may consist of wires having diameters of from 0.2 to 0.3 mm. and the windings may include from 20 to 30 turns each, with both coils wound in the same direction.
The drum core 6 and flanges 7 and 8 of the present invention may be composed of a core material such as iron, silicon, steel, permalloy, or permendure. It is preferable to use a dust core, such as pure iron dust core, permalloy dust core, sendust core or ferrite. In the preferred embodiment, the diameter of the end flanges may be on the order of 3 cm., and that of the core may be on the order of 1 cm.
Although inductance coils having circular flanges have been illustrated, it is contemplated that the flanges may be of many other shapes, such as square, triangular and the like.
Referring now to FIG. 5, the following dimensions are illustrated:
a thickness of end flange 8 a :thickness of end flange 7 b :distance between end flange 8 and intermediate flange 9 b :distance between end flange 7 and intermediate flange 9 c zdiameter of end flange 8 c diameter of end flange 7 diameter of intermediate flange 9 e thickness of intermediate flange 9 i diameter of the central core at the position of coil diameter of the central core at the position of coil Observing these dimensions, the self-inductance of coils l and 11 can easily be made equal if core 6 is made such that:
0 c and In addition, the mutual inductance of the coil can be set to a particular value by properly selecting the dimensions d and e.
Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.
1. A derived m-type filter comprising:
a cylindrical core having flange means at both ends thereof, both of said end flange means having equal heights and widths and comprised of essentially homogeneous masses;
intermediate flanges means positioned on said core between said end flange means;
coil winding regions defined by the spaces between said intermediate flange means and said end flange means, each of said coil winding regions having identical widths and heights;
coils wound around said core, one coil in each of said coil winding regions, each of said coils having the same number of turns, and each of said coils wound about said core in the same direction and connected to one another in series at each of said intermediate flange means; and
externally provided capacitor means coupled to said coils at each of said connection points therebetween.
2. A derived m-type filter as set forth in claim 1, wherein: said core and all said flange means are formed of ferrite.
3. A derived m-type filter as set forth in claim 1, wherein:
said intermediate flange means comprises a plurality of flange members each comprised of an essentially homogeneous mass arranged along said core at regular intervals.
4. A derived m-type filter as set forth in claim 1, wherein: all said flange means are moulded integral with said core.
5. A derived m-type filter as set forth in claim 1, wherein: all said flange means are disk shaped, having apertures in the centers thereof whereby said flange means are mounted on said core.
6. A derived mtype filter as set forth in claim 5 wherein the ratio of the diameter of said end flanges to the diameter of said core is approximately 3:1.