JPH0536549A - Small-sized power transformer - Google Patents

Abstract

PURPOSE:To provide a small-sized power transformer having a simple structure and a small magnetic leakage even when it is contained in a monitor television unit. CONSTITUTION:An entire magnetic transformer is covered with a magnetic shielding box 1 by covering a stationary base 3 in which a magnetic transformer 2 is mounted, with the box 1 formed with an opening 1a at its bottom.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small-sized power transformer which is preferably used by being incorporated in a monitor television unit used in a doorphone system with a camera.

[0002]

2. Description of the Related Art Since a power transformer of this type is placed in the unit main body in the vicinity of a monitor television, it is desired to prevent the disturbance of the image due to the leakage magnetic flux of the monitor television. Conventional power transformers have a structure as shown in FIGS. 6 and 7 that is directly attached to the circuit board, or a type as shown in FIGS. 8 and 9 in which metal fittings are attached to the iron core of the transformer. There is something. 6 and 7, reference numeral 200 indicates a structure in which a coil 201 is wound around an EI core 200 formed of a silicon steel plate, and a terminal 202 is provided on the lower portion, so that the terminal 202 can be directly attached to a circuit board (not shown). 8 and 9, the coil 301 is wound around the center of the yoke 300, the output terminals 304 and 304 are led out from the upper part, and the terminals 305 and 305 are led out from the center of the coil 301. The pedestals 302, 302 are attached to the substrate with screws or the like. Further, instead of the power transformer as described above, in order to prevent magnetic leakage to the outside, a magnetic transformer 103 having a winding portion 102 provided in a core 101 is provided in a magnetic shield box 100 made of a silicon steel plate and having an opening 100a on the upper surface. In the structure as shown in FIG. 5 in which the magnetic transformer 103 is built in and fixed to the magnetic shield box 100 by spot welding 104, 104,
Magnetic flux leaks from the spot welds 104, 104,
Magnetic flux leaks from the top opening 100a of the magnetic shield box 100, which adversely affects the peripheral circuits.

[0003]

However, when such a structure is built in the monitor / television unit, the shield is not sufficient in either case,
It has been a cause of generating magnetic flux leakage and disturbing the image on the monitor TV. The present invention has been proposed to solve the above problems, and an object thereof is to provide a power supply transformer having a simple structure and in which leakage magnetic flux is unlikely to occur.

[0004]

SUMMARY OF THE INVENTION A power transformer according to the present invention, which is proposed to achieve the above object, has a magnetic field whose bottom surface is opened from above a fixed base on which the power transformer is mounted. In the power transformer of the present invention proposed in claim 2, the magnetic shield box is formed by bending a silicon steel plate. The structure is formed by.

[0005]

According to the present invention as set forth in claim 1, since the power transformer is entirely covered by the magnetic shield box from above, the upper part of the magnetic shield box should be close to the monitor TV side. If it is placed inside the main body of the TV unit, the effect of magnetic leakage on the monitor TV can be effectively prevented. Further, according to the present invention described in claim 2, since the magnetic shield box is formed by bending a thin silicon steel plate, the magnetic shield box can be manufactured easily and the shield can be simplified.

[0006]

An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an exploded perspective view showing a configuration of a main part of a power transformer A of the present invention. Reference numeral 1 is a magnetic shield box having an opened bottom surface 1a. As shown in a developed view of FIG.
It is formed by bending a thin silicon steel plate. In the development view shown in FIG. 2, reference numeral 1c denotes four side pieces that form the peripheral wall of the magnetic shield box 1. Of these four side pieces, a pair of mounting small pieces 1d, are provided on both sides of a pair of side walls facing each other. 1d is formed. The magnetic shield box 1 includes mounting pieces 1d and 1d.
Are fixed to both side surfaces of the adjacent side pieces 1c, 1c with an adhesive or the like, and the side pieces 1e are assembled into a box shape with the lid piece.

In the magnetic transformer 2, a large number of thin silicon steel plates 20 are laminated to form an EI core, and primary and secondary windings are alternately wound around the EI core to form a winding portion 2a. Formed.
The structure is such that two input and output lines 21 and 22 are drawn from this winding portion 2a, and two input and output lines 21 and 22 are provided.
It has a structure in which connection plugs 21a and 22a are provided at the respective tips. Reference numeral 3 is a fixing base formed of a magnetic material for fixing the magnetic transformer 2.
Bottom surface 32 having a hole 3a into which the winding portion 2a of
Both sides of the pedestal are bent to form a set of pedestals 33, 33. Each of the pedestals 33, 33 has a screw hole 33a, 3
3a is formed. Also, above the fixed base 3,
The four protruding pieces 31 are formed, and the winding portion 2a of the magnetic transformer 2 is fitted into the hole 32a of the bottom surface 32, and then each tip of the protruding piece 31 is bent inward. Is fixed to the fixing base 3. The recess 1c formed at the lower edge of the magnetic shield box 1
Are input and output lines 21 and 2 derived from the magnetic transformer 2.
It is a 2 outlet. According to this structure, the magnetic transformer 2 is fixed to the fixed base 3 by fitting the winding portion 2a of the magnetic transformer 2 into the hole 3a of the bottom surface 32 and then bending the tip of the protruding piece 31 of the fixed base 3. Fix to 3. And
If the magnetic shield box 1 is covered from above, the magnetic shield box 1 will cover the magnetic transformer 2 from above so that the screw 4 is inserted from the screw insertion hole 1b of the magnetic shield box 1 to fix the fixed base. The screw 4 is screwed into the screw hole 3b of 3 and finally the insulating tape 1 is attached to the bottom of the magnetic shield box 1.
If 1 (indicated by a broken line in the figure) is wound and fixed in the shape of a headband, the magnetic transformer 2 can be housed in the magnetic shield box 1 and easily fixed. Thus, the power transformer A can be easily fixed by screwing a screw (not shown) into the pedestal 33 side below the fixed base 3 covered with the magnetic shield box 1.

FIG. 3 shows an example in which the power transformer of the present invention is mounted in the main body case of a cordless parent telephone having a built-in monitor television. An RF circuit 8 for constructing a wireless transmission / reception unit of a cordless telephone is built in the main body case 6 of the main unit, and a power transformer A of the present invention is placed on the opposite side of the main body case 6 having an antenna 7. From the back surface, the screw 5 is screwed into the screw hole 33a formed in the pedestal 33 of the fixed base 4 of the power transformer A as shown in the figure to fix the screw 5. Note that FIG. 4 shows the inner surface side of the cover body 9 that is integrally assembled above the main body case 6 of the cordless master telephone. As shown in FIG. 4, on the inner surface of the cover body 9, a push button control circuit 13 of a telephone set, a camera doorphone, and a video 2-line control circuit 11 of a monitor TV (only the circuit board is shown in the figure) are attached. And monitor TV 12
Is attached to the cover body 9 such that its display portion is aligned with the display window 10 of the cover body 9.

[0009]

According to the present invention, as described above, since it has a simple structure and is effective for magnetic leakage, it can be used by being built in a monitor TV unit, etc., and the degree of freedom in design increases, and the monitor It can contribute to the miniaturization of TV units.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a power transformer of the present invention.

FIG. 2 is a development view of a magnetic shield box.

FIG. 3 is a diagram showing the inside of a main body case of a cordless master phone with a monitor TV to which the power transformer of the present invention is attached.

FIG. 4 is a diagram showing the inside of a cover body of a cordless master phone with a monitor TV.

FIG. 5 is an example diagram of a conventional power transformer in which a magnetic transformer is attached to a magnetic shield box by spot welding.

FIG. 6 is an example diagram of a conventional power transformer.

FIG. 7 is a bottom view of the power transformer shown in FIG.

FIG. 8 is a diagram showing still another example of the conventional power transformer.

9 is a bottom view of the power transformer shown in FIG.

[Explanation of symbols]

A: Power transformer of the present invention 1 ... Magnetic shield box 2 ... Magnetic transformer 3 ... Fixed stand

Claims (2)

[Claims] 1. A small power transformer having a structure in which a magnetic shield box having an open bottom is covered from above a fixed base to which the power transformer is attached, and the entire power transformer is covered with the magnetic shield box. 2. The small power transformer according to claim 1, wherein the magnetic shield box is formed by bending a silicon steel plate.