JP2949127B2 - Planar type transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar transformer using a magnetic thin film.

[0002]

2. Description of the Related Art Magnetic transformers are used for switching power supplies.
Transformer for power supply such as DC-DC power supply, step-up transformer,
It is used as a transformer for weak signal voltage amplification. 2. Description of the Related Art In a power supply unit mounted on an electronic device, particularly a portable electronic device or the like, space saving is required along with miniaturization of the device. In addition, in order to save the space of the entire power supply unit, it is necessary to satisfy a characteristic requirement such as improvement of a switching frequency, and a magnetic transformer having performance corresponding to the requirement is required.

Further, in consideration of mounting on an electronic device, it is desirable to use a flexible device having a slight deformation and a followability to the shape of the mounting portion. It is known that a magnetic yoke portion of a conventional bulk type transformer is thinned to form a thin film transformer (JP-B-55-13416, JP-A-61-208210). By reducing the thickness of the magnetic yoke, the size and thickness of the transformer can be reduced, and the property of a magnetic thin film that has good high-frequency magnetic characteristics can be used.

However, the conventional thin film type transformer is
It was said that it was not suitable for high output due to magnetic saturation and the like.
Further, Japanese Patent Application Laid-Open No. 62-214604 describes that a coil pattern is formed on a sheet that becomes a magnetic material by sintering, and this is laminated to form a laminated transformer. However, this transformer is inflexible and has great restrictions when mounted on an electronic device.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic transformer which is flexible, can follow some deformation, and which can be reduced in size, thickness and output.

[0006]

A planar transformer according to the present invention is a magnetic transformer having a primary winding and a secondary winding, wherein a magnetic yoke is a long flexible substrate on which a soft magnetic thin film is formed. Is wound a plurality of times.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a planar transformer of the present invention, a magnetic thin film made of a soft magnetic material is formed on a flexible substrate to form a magnetic yoke. Here, examples of the flexible substrate include films and sheets of various flexible plastics.

As the soft magnetic material, a material having a high effective transmittance at a high frequency and a high saturation magnetic flux density is desirable. Specifically, an amorphous film such as Co-Zr-Nb or a laminated film thereof, a thin film such as iron nitride or a laminated film thereof, a thin film such as an alloy of Fe and Co or a laminated film thereof, or a laminated film thereof are used. Can be

The magnetic thin film is formed by the above soft magnetic material by sputtering, vacuum film formation such as vacuum deposition, plating method or the like, or screen printing method using a suitable binder after the soft magnetic material is once finely divided. it can.

As the primary winding and the secondary winding, a normal wire made of an insulating-coated conductor, a conductor foil, or a conductor film formed by a photolithographic method or the like is used.

FIG. 1 is a perspective view showing an embodiment of a planar transformer according to the present invention. Two flexible yokes 15 each having a magnetic thin film 13 formed on a flexible substrate 11 are adhered with an adhesive or the like to form a magnetic yoke. Flexible yoke
Reference numeral 15 denotes a disk having a through hole at the center, and a primary winding 21 and a secondary winding 23 each formed of an insulated conductor are wound around a flexible yoke 15.

FIG. 2 is a perspective view showing another embodiment of the present invention. A tape-shaped flexible yoke 15 having a magnetic thin film formed on a flexible substrate is wound to form a magnetic yoke, and a primary winding 21 made of a conductor insulated and coated around the magnetic yoke.
And the secondary winding 23 is wound. Since the flexible yoke 15 has a sufficient dimensional ratio, it forms a closed magnetic circuit in terms of a magnetic circuit.

In the above two planar type transformers, the magnetic flux generated by the primary current from the primary winding 21 is formed by the flexible thin film 13 formed on the flexible substrate 11 in the same manner as a normal magnetic transformer. After passing through the yoke 15, a voltage proportional to the time change of the magnetic flux passing through the flexible yoke 15 is generated in the secondary winding 23, and a current flows according to an appropriate load. Is transmitted to

In the planar type transformer shown in FIGS. 1 and 2, the flexible yoke 15 is flexible and responsive, so that the flexible yoke 15 can be adhered and fixed so as to follow the shape of a portion to be attached to an electronic device or the like. It can be stored and mounted between device members by bending or bending. In addition, by increasing the number of layers of the flexible yoke 15 in FIG. 1 and by increasing the number of turns in FIG. 2, it is possible to cope with high output.

FIG. 3 is an exploded perspective view showing another embodiment of the planar transformer according to the present invention, and FIG. 4 is a longitudinal sectional view thereof.

A primary winding 21 made of a conductive foil and a secondary winding 23 made of the same conductive foil form an insulating sheet 31 (insulating spacer).
Are laminated through. Although this embodiment shows a case where the primary winding 21 has one turn and the secondary winding 23 has two turns, the number of turns can be set as appropriate. Reference numerals 33 and 35 both denote insulators.

Further, the upper side of the secondary winding 23 and the primary winding
Insulating sheets 31 and 31 are arranged below the lower surface 21 so that the entire laminated body of the primary winding 21 and the secondary winding 23 is covered with the insulating sheet. , 15. At this time, the upper flexible yoke 15 has the magnetic thin film 13 facing downward, and the lower flexible yoke 15 has the magnetic thin film 13 facing upward so as to face it. The upper and lower magnetic thin films 13 and 13 surround the primary winding 21 and the secondary winding 23 so as to surround the outer peripheral portion 15a and the central portion 15b (see FIG. 4).
And are directly bonded to each other by an adhesive or the like. That is, the magnetic thin films 13, 13 are in direct contact with each other at the central portion 15b and the outer peripheral portion 15a, and are closed in a magnetic circuit (forming a closed magnetic path).

In the above embodiment, the primary winding 21 and the secondary winding 23 are provided around the flexible substrate 11
The flexible yoke 15 composed of the magnetic thin film 13 formed thereon is arranged so as to be coupled in a distributed manner via the corresponding portion.
The primary winding 21 and the secondary winding 23 are connected to the surrounding flexible yoke.
15, the inductance coupling is performed densely through the relevant portion, and the strength of the coupling is determined by the windings 21 and 23 and the flexible yoke 15.
It can be set freely according to the dimensions and arrangement of the parts. Further, it can be changed depending on the material of the magnetic thin film 13 formed on the flexible substrate 11. In accordance with this inductance coupling, the power given to the primary is transmitted to the secondary.

FIG. 5 shows an application example of the planar type transformer of the present invention, and shows a case where it is used for an image reading sensor. FIG. 6 is a block diagram thereof.

The supporting member 53 includes a light detecting section 57 and an arithmetic processing section 5.
9. Xe lamp 55 for document illumination is supported. Electric power from an external power supply is input to the entire power supply unit 51 including the Xe lamp drive circuit, boosted by the planar transformer 41 (the present invention), and supplied to the Xe lamp 55. 43 indicates a primary winding, and 45 indicates a secondary winding.

In the case of a Xe tube used as an illumination source of an image reading sensor, a drive circuit capable of driving at 1 KHz or more and 100 V or more is required. Conventionally, since a step-up transformer must be provided, it is often configured as an independent part as a drive circuit, and since this step-up transformer is made of a magnetic yoke of a bulk material such as ferrite, it is dimensionally large. Had become.

On the other hand, according to the planar type transformer of the present invention, it is possible to make it extremely thin, and because it is flexible, it is somewhat flexible and easy to mount, and it is extremely easy to mount the Xe tube or the like. It became possible to arrange it near. In the case of the image reading sensor, since the other parts of the drive circuit are minute, it is not necessary to configure the planar transformer as an independent part, and a remarkable effect can be obtained in reducing the size and weight.

[0023]

According to the present invention, a soft magnetic thin film is formed on a flexible substrate to form a flexible magnetic yoke, so that the magnetic transformer can be reduced in size and thickness. This is extremely advantageous in terms of mounting because it has a property.

Further, since the magnetic thin film is used, it has excellent high frequency characteristics, and can cope with an increase in output by lamination. In particular, by adopting distributed coupling, power transfer characteristics in a high frequency region are improved, and a higher frequency and a higher rate of the power supply can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a planar transformer according to the present invention.

FIG. 2 is an explanatory diagram showing another embodiment of the present invention.

FIG. 3 is an exploded perspective view showing still another embodiment of the present invention.

FIG. 4 is a vertical sectional view of the planar transformer shown in FIG. 3;

FIG. 5 is an explanatory diagram showing an application example of the planar transformer of the present invention.

FIG. 6 is a block diagram of an application example of FIG. 5;

[Explanation of symbols]

 11 Flexible substrate 13 Magnetic thin film 15 Flexible yoke 21 Primary winding 23 Secondary winding 31 Insulation sheet 33,35 Insulator 41 Planar transformer 43 Primary winding 45 Secondary winding 51 Power supply unit 53 Support member 55 Xe lamp 57 Light detector 59 Arithmetic processor

Claims (3)

(57) [Claims] In a magnetic transformer having a primary winding and a secondary winding, a magnetic yoke is formed by winding a long flexible substrate on which a soft magnetic thin film is formed a plurality of times. Planar type transformer. 2. A magnetic circuit comprising: a primary winding and a secondary winding stacked so that surfaces including the respective winding directions overlap each other; and a surrounding of the winding laminated body is covered with a soft magnetic thin film to constitute a magnetic circuit. The planar type transformer according to claim 1, wherein 3. A magnetic transformer having a primary winding and a secondary winding, wherein a magnetic yoke is a planar type transformer made of a soft magnetic thin film formed on a flexible substrate.
A method for driving a xenon lamp, comprising raising a power supply voltage and supplying the xenon lamp to the xenon lamp.