JPH04133408A - Plane-surface transformer - Google Patents

Abstract

PURPOSE:To obtain the title transformer having excellent noisepreventing characteristics by a method wherein the generation of electrostatic coupling is prevented and electric capacitance is lowered by interposing an electrostatic shielding member, consisting of conductive non-magnetic material, between plane-surface coils. CONSTITUTION:In a plane-surface transformer, wherein a plurality of plane- surface coils 1a and 1b, on which a coil is flatly formed, are laminated through an electric insulating material 3 and the laminated body is pinched by magnetic materials 4a and 4b through the intermediary of the insulating material 3, an electrostatic shielding member 6, consisting of conductive non-magnetic material, is interposed between the above-mentioned plane-surface coils 1a and 1b. For example, the magnetic material 4a, the primary planar coil 1a, the electrostatic shielding plate 6, the secondary planar coil 1b and the magnetic material 4b are successively laminated in the above-mentioned order from above through the intermediary of the electric insulating material 3, and the magnetic material 4a and 4b and the electrostatic shielding plate 6 are earth-coupled. The good conductivity metal foil of non-magnetic material such as aluminum, copper and the like is suitable for the electrostatic shielding plate 6.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Field of Industrial Application) The present invention relates to a thin, small and lightweight planar transformer suitable as a transformer for power supplies, inverters, oscillators, etc. Concerning an improved planar transformer.

(Prior art) Some general transformers consist of a primary coil and a secondary coil formed by spirally winding copper wire on the primary and secondary sides of an iron core, respectively. There were limits to miniaturization, weight reduction, and thickness reduction.

On the other hand, in recent years, planar coils such as inductance elements and sliced coils in which conductors are spirally printed on printed circuit boards have been proposed.

Sliced coils are manufactured by first spirally winding a conductive thin strip of the desired width to form a roll, and then slicing the rolled material in the axial direction to the desired width. be done. FIG. 2 shows such a planar coil 1, in which a conductor 2 is formed in a spiral shape on one plane.

Therefore, it has been devised to create a thin, small, and lightweight planar transformer using such a planar coil. That is, as shown in FIG. 3, a memorial service planar coil 1a and a secondary planar coil 1b are laminated with an electric insulator 3 in between, and magnetic bodies 4a are placed on both sides of this laminate with an electric insulator 3 in between. , 4b are laminated, and a thin, small and lightweight planar transformer can be obtained.

(Problem to be Solved by the Invention) However, when such a planar transformer is used in a transmission line, external noise such as transient pulses and pulse-like noises caused by sirisk becomes important to the planar coil 1a. In the planar transformer shown in Fig. 3, since the planar coil 1a and the secondary planar coil 1b are structurally electrostatically coupled, noise components are transmitted to the secondary planar coil 1b. There was a problem that That is, the above-mentioned planar transformer was not electrostatically shielded, and measures against noise were insufficient. Figure 4 shows the primary coil 1a and secondary coil 1b in such a planar transformer.
This figure shows an equivalent circuit showing the capacitive coupling of , where 5 is the capacitance between these coils.

The present invention was made to solve the above problems, and
By preventing electrostatic coupling between planar coils and reducing capacitance, noise blocking characteristics prevent noise components from being transmitted to the secondary side even if noise is added to the negative side. The purpose is to provide an excellent planar transformer.

[Structure of the Invention] (Means for Solving the Problems) That is, the planar transformer of the present invention includes a plurality of planar coils each formed into a planar shape, which are laminated with electrical insulators interposed therebetween, and the laminated body is This is a planar transformer in which a magnetic material is sandwiched between electrical insulators and magnetic materials, and an electrostatic shielding member made of a conductive non-magnetic material is interposed between the planar coils.

(Function) In the planar transformer of the present invention, by interposing an electrostatic shielding member made of a conductive non-magnetic material between the planar coils, the electrostatic shielding effect between the planar coils is improved and the electrostatic Capacity is significantly lower than before. Therefore, it is possible to obtain a low-noise planar transformer that has an excellent ability to block noise such as noise.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. Note that the same reference numerals are added to the same parts as in the conventional example.

FIG. 1 shows an embodiment of the planar transformer of the present invention, in which, from the top, a magnetic body 4a, a memorial service planar coil 1a, an electrostatic shield plate 6, a secondary planar coil 1b, and a magnetic body 4.
They are all laminated in the order of b with electrical insulators 3 interposed therebetween. Then, the magnetic material 48% 4b and the electrostatic shield plate 6
is bonded to ground.

The electrostatic shield plate 6 used here is preferably a non-magnetic and highly conductive metal foil such as aluminum or copper, but is not limited thereto.

By configuring the planar transformer as described above, it is possible to take measures against electrostatic shielding between the negative side planar coil and the secondary side planar coil, and the capacitance of the conventional planar transformer was several 1009 F. However, in the planar transformer of the present invention, the equivalent capacitance can be reduced to about several 10<9 >P. Therefore, according to the present invention, the noise blocking ability of the planar transformer can be improved by several tens of dB compared to the conventional method.

In addition, in this example, a planar transformer using two layers of planar coils was explained, but in the present invention, the number of planar coils is not limited to two layers, and the same effect can be obtained even if there are multiple layers of planar coils. is obtained.

[Effects of the Invention] As explained above, according to the present invention, by interposing a non-magnetic conductive plate between planar coils, it is possible to improve the electrostatic shielding effect, and the electrostatic Capacity can be significantly reduced. Therefore, it is possible to obtain a thin, small, lightweight, low-noise planar transformer with significantly improved noise rejection characteristics.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a planar transformer according to an embodiment of the present invention, Fig. 2 is a sectional view showing a conventional planar transformer, Fig. 3 is a plan view showing an example of a planar coil, and Fig. 4 is a primary FIG. 3 is an equivalent circuit diagram showing electrostatic coupling between a planar coil and a secondary planar coil. DESCRIPTION OF SYMBOLS 1...Planar coil, 1a...-Memorial planar coil, 1b...Secondary planar coil, 2...Conductor, 3...Electric insulator, 4a, 4b...Magnetic material , 5...Capacitance, 6...Electrostatic shielding plate applicant Toshiba Lightic Corporation

Claims (1)

[Claims] (1) In a planar transformer in which a plurality of planar coils each having a coil formed in a planar shape are laminated with electrical insulators interposed therebetween, and the laminated body is sandwiched between magnetic materials with each electrical insulator interposed in between, A planar transformer characterized in that an electrostatic shielding member made of a conductive non-magnetic material is interposed between planar coils.