JPH03280408A - Planar inductance element - Google Patents

Abstract

PURPOSE:To contrive flattening of magnetic flux density on the center part and the outer circumferential part of a conductor by a method wherein a plane-surfaced coil, with which a conductor is spirally wound, is pinched by a pair of magnetic bodies through the intermediary of an insulator, and the above-mentioned plane-surfaced coil is wound in such a manner that it becomes coarser as approaching closer to the spiral center part. CONSTITUTION:A plane-surfaced inductance element 11 is constituted in such a manner that both front and back sides of a plane-surfaced coil 12 are pinched by a pair of magnetic materials 14a and 14b through the intermediary of a pair of electrically insulated members 13a and 13b. The plane-surfaced coil 12 is formed by spirally winding a conductor 12a on a plane surface in such a manner that the winding pitch P0 of its center part O becomes larger than the winding pitch PG of the outer circumferential part G, namely, the wire turns become smaller as the center part O is approached. Accordingly, the peak of density of magnetic flux distributed on the center part of the pair of magnetic bodies 14a and 14b corresponding to the center part of the spiral winding is suppressed. On the other hand, the density of magnetic flux on the outer circumference G of the spiral winding is enhanced, and the magnetic flux density of the flat-surfaced inductance element 11 can be made almost flat at the center part and the outer circumferential part.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a small and thin planar inductance element suitable as an inductance element for power supplies, inverters, oscillators, etc. This invention relates to a planar inductance element that has improved.

(Prior technology) Conventional inductance elements are made by winding copper wire into a coil, but since the inductance is proportional to the diameter and the square of the number of turns, there is a limit to miniaturization and thinning. there were.

Therefore, in recent years, planar coils such as inductance elements and sliced coils in which conductors are printed in a coiled or spiral shape on a printed circuit board have been proposed.

A slicing coil is made by first spirally winding a conductive thin strip of the required width to form a spiral cylinder, and then slicing this spiral cylinder to the required length in the axial direction. Consisted of.

FIG. 3 shows a plan view of an example of such a planar coil 1, in which a conductor 2 is spirally wound on one plane.

Further, this planar coil 1 has conventionally been assembled into a planar inductance element.

In other words, this type of conventional planar inductance element is constructed by sandwiching both the front and back surfaces of the planar coil 1 between two pairs of magnetic materials made of amorphous alloy, etc., via two pairs of electrical insulators. has been done.

(Problem to be Solved by the Invention) However, in such a conventional planar inductance element, there is a problem that the magnetic flux density is concentratedly distributed and forms a peak in the center of a pair of magnetic bodies, and the magnetic flux density is omnipresent. be.

Therefore, as a result of repeated various experiments to investigate the cause, the present inventors found that the conductor 2 in the planar coil 1
It has been learned that the above cause exists in that the spiral winding pitch (interval) of the spiral is approximately equal between the center of the spiral and the outer periphery thereof.

The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a planar inductance element that can flatten the magnetic flux density in the central portion and the outer peripheral portion thereof.

[Structure of the Invention] (Means for Solving the Problems) The present invention is constructed as follows in order to solve the problems described above.

In other words, the present invention provides a planar inductance element in which a planar coil in which a conductor is formed in a spiral shape is sandwiched between a pair of magnetic materials via respective insulators, in which the conductor of the planar coil is separated from its spiral outer periphery. It is characterized by being wound so that it gradually becomes sparser toward the center of the spiral.

(Function) Spiral winding pitch (spacing) of conductor in a planar coil
is larger at the center of the spiral than at its outer periphery and is loosely wound, so the magnetic flux density at the center of the pair of magnetic bodies corresponding to the center of the spiral of this planar coil decreases, and this peak is suppressed.

On the other hand, since the conductor is tightly wound around the spiral outer periphery of the planar coil, the magnetic flux density at the outer periphery of the pair of magnetic bodies corresponding to this spiral outer periphery is increased accordingly.

Therefore, according to the present invention, the magnetic flux density of the planar inductance element can be made substantially flat between the central portion and the outer peripheral portion.

(Example) An example of the present invention will be described below based on FIGS. 1 and 2.

FIG. 1 is a longitudinal cross-sectional view of an embodiment of the present invention. In the figure, a planar inductance element 11 connects both the front and back surfaces of a planar coil 12 through a pair of electrical insulators 13a and 13b, respectively. It is constructed by being sandwiched between a pair of magnetic bodies 14a and 14b made of an amorphous alloy or the like.

As shown in FIG. 1, the planar coil 12 has a conductor 12a spirally wound on one plane, and has a winding pitch P at the center O of the spiral.

is set to be larger than the winding pitch P6 of the spiral outer peripheral portion G.

In other words, the conductor 12a is wound so that it becomes looser as it goes toward the center 0 of the spiral.

Therefore, the peak of the magnetic flux density distributed at the center of the pair of magnetic bodies 14a, 14b corresponding to the spiral center O of the planar coil 12 is suppressed.

On the other hand, since the conductor 12a is tightly wound around the spiral outer periphery G of the planar coil 12, the magnetic flux density at the outer periphery of the pair of magnetic bodies 14a and 14b corresponding to the spiral outer periphery G is increased.

Therefore, the magnetic flux density of the planar inductance element 11 can be made substantially flat between the central portion and the outer peripheral portion.

In addition, although the case where the spiral shape of the planar coil 12 was circular was demonstrated in the said Example, this invention is not limited to this, For example, a square spiral shape may be sufficient.

〔Effect of the invention〕

As explained above, the present invention provides a planar coil conductor,
Since the spiral is wound so that it becomes gradually looser as it goes from the outer circumference of the spiral to the center of the spiral, the peak of the magnetic flux density at the center of the spiral can be suppressed and the magnetic flux density at the outer circumference of the spiral can be flattened.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the planar coil shown in FIG. 2, FIG. 2 is a longitudinal sectional view of an embodiment of the planar inductance element according to the present invention, and FIG. 3 is a plan view of a conventional planar coil. . DESCRIPTION OF SYMBOLS 11... Planar inductance element, 12... Planar coil, 13a, 13b-insulator, 14a, 14b...
・Magnetic material.

Claims (1)

[Claims] In a planar inductance element in which a planar coil in which a conductor is formed in a spiral shape is sandwiched between a pair of magnetic materials via respective insulators, the conductor of the planar coil is moved from the outer periphery of the spiral to the center of the spiral. A planar inductance element characterized in that it is wound so that it becomes gradually sparse according to the following.