JPH0751785Y2 - Flyback transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a flyback transformer used in a deflection circuit separation type high voltage generating circuit.

[Conventional technology]

There are two types of high-voltage generating circuits for television receivers and display devices, one with a horizontal deflection coil integrated and the other with a horizontal deflection coil separated. An example is shown in FIG. In the high-voltage generating circuit of the type in which the horizontal deflection coil is separated, the choke coil 2 is connected in parallel with the primary coil 3 of the flyback transformer 1 in order to improve the regulation characteristics of the flyback transformer 1. As shown in FIG. 6, the choke coil 2 has a coil winding wound around the bobbin 4 and the central magnetic leg 5a of the E-shaped core 5 as shown in FIG. 7 is inserted in the core insertion hole of the bobbin. The E-shaped core 5 is fitted and the I-shaped core 6 is abutted on the end face side of the magnetic leg of the E-shaped core 5 to form a closed magnetic path.

The flyback transformer 1 has a primary coil 3 and a secondary coil 8 fitted on the outside thereof.
And the coil assembly of the secondary coil 8 is the transformer case 7
The transformer case 7 and the transformer case 7 are integrated with each other by molding with a casting resin, and a pair of U-shaped cores 10 common to the primary coil 3 and the secondary coil 8 are inserted from the outside of the transformer case 7 from above and below. The flyback transformer 1 and the choke coil 2 are separately fitted and mounted on the circuit board 9,
The wirings 1 and 2 are connected by wiring or by using a printed circuit formed on the circuit board 9. In FIG. 5, 11 is a horizontal output transistor, 12 is a damper diode, 13 is a resonance capacitor, 14 is a rectifying diode that divides the secondary coil 8 into a plurality of parts, and 15 is a high voltage output of the secondary coil 8. Each of the high-voltage rectifying diodes added to the cathode ray tube (not shown) is shown.

[Problems to be solved by the device]

However, since the flyback transformer 1 used in the horizontal deflection coil separation type high voltage generation circuit is configured separately from the choke coil 2, when the flyback transformer 1 and the choke coil 2 are incorporated in the circuit board 9. However, there is a problem that the work of assembling into the circuit board 9 becomes complicated because it must be performed separately.

Further, since the choke coil 2 is connected in parallel with the primary coil 3 of the flyback transformer 1, the impedance tolerance of the choke coil 2 and the flyback transformer 1 are also connected.
There is a problem that the tolerance of the impedance of the primary coil 3 is added and the tolerance of the parallel impedance of the both coils 2 and 3 becomes large.

In addition, recently, a series of research reports have been published that the low-frequency leakage magnetic field and the leakage electric field leaking from the cathode ray tube have an adverse effect on the human body, and at present, a definitive conclusion of their harmfulness and harmlessness has been reached. However, there is growing social interest in these leakage magnetic fields and electric fields, and countermeasures against them are desired. It is known that this low frequency leakage magnetic field or leakage electric field is also generated from the flyback transformer. In the conventional horizontal deflection coil separation type high voltage generating circuit, the winding direction of the coil of the choke coil 2 is not particularly fixed, and the coils 3, 8 of the flyback transformer 1 are not specified.
If the choke coil 2 is wound so that the magnetic field or the electric field is generated in the same direction as the leakage magnetic field or the electric field from, the leakage magnetic field or the electric field on the flyback transformer side is added by the magnetic field or the electric field leaking from the choke coil 2. However, even if the choke coil 2 happens to be wound in a direction that cancels the leakage magnetic field or electric field leaking from the flyback transformer, the choke coil 2 has the EI type core as described above. Because it is used
The leakage magnetic field or electric field in the canceling direction is originally small, the magnetic field or electric field leaking from the flyback transformer 1 cannot be effectively canceled, and sufficient countermeasures against the low frequency leakage magnetic field or electric field cannot be taken. There was a problem.

The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to facilitate the work of assembling the flyback transformer and the choke coil on the circuit board, and further, to further improve the primary coil and the choke coil of the flyback transformer. Can reduce the parallel impedance tolerance of
(EN) A flyback transformer capable of effectively canceling a leakage magnetic field and an electric field leaking from a primary coil and a secondary coil of the flyback transformer.

[Means for Solving the Problems]

The present invention is configured as follows to achieve the above object. That is, the present invention relates to a flyback transformer used in a horizontal deflection coil separation type high voltage generating circuit having a choke coil, wherein the choke coil is wound in a direction canceling a leakage magnetic field leaking from the flyback transformer. It is connected in parallel to the primary coil of the transformer, the coil of the flyback transformer and the choke coil are housed in the transformer case, the choke coil is integrated with the flyback transformer, and the choke coil is the end surface of the leg. Is provided with a pair of U-shaped cores that are fitted to each other, and a gap is formed between the abutting end surfaces of the U-shaped cores.

[Action]

In the present invention, the primary coil and the secondary coil of the flyback transformer are housed together with the choke coil in the transformer case, and are integrally formed. By incorporating the flyback transformer in the circuit board, the choke coil is also incorporated in the circuit board. Be incorporated at the same time. The magnitude of the parallel impedance between the primary coil of the flyback transformer and the choke coil is adjusted by changing the gap formed in the U-shaped core of the choke coil.

Further, the magnetic field and electric field leaking from the choke coil are opposite in direction to the low frequency leaking magnetic field and electric field leaking from the primary coil and the secondary coil of the flyback transformer, and moreover, the U-shaped core is used for the choke coil. The magnetic field and electric field leaking from the choke coil are also relatively large, and the magnetic field and electric field leaking from the primary coil and the secondary coil of the flyback transformer are effectively canceled by the magnetic field and electric field leaking from the choke coil.

〔Example〕

An embodiment of a flyback transformer according to the present invention will be described below with reference to the drawings. In the description of the present embodiment, the same parts as those of the conventional example are designated by the same reference numerals, and detailed description thereof will be omitted. 1 to 4 show an embodiment of a flyback transformer according to the present invention. FIG. 1 shows the flyback transformer of this embodiment together with a horizontal deflection coil separation type high voltage generating circuit. A choke coil 2 is connected in parallel to a primary coil 3 of the flyback transformer as in the conventional example. There is.

As shown in FIG. 2, the core of the choke coil 2 is composed of a pair of U-shaped cores 16. This pair of U-shaped core
The end faces of the magnetic legs 17 of 16 are butted against each other via a gap 18, and the coil assembly 20 of the primary coil 3 and the secondary coil 8 is fitted and inserted on the one butted magnetic leg side. The pair of U-shaped cores 16 are sandwiched by spring holding members 21, and are held so that the U-shaped cores 16 do not come off from the coil portion 20.

The choke coil 2 is formed by winding a coil winding around a bobbin, but in this embodiment, the leakage magnetic field and electric field leaking from the choke coil 2 cause the coil 3,
The winding direction of the coil winding is set so that it is generated in the direction opposite to the low-frequency leakage magnetic field and electric field that leak from 8 The choke coil 2 in which the coil winding is wound around the bobbin in this way is formed by fitting the bobbin with the bobbins of the coils 3 and 8 on the flyback transformer side.
3,8,2 are integrated. In this state, after the choke coil 2 and the primary coil 3 of the flyback transformer are connected in parallel, the integrated flyback transformer coils 3 and 8 and the choke coil 2 are housed in the transformer case 7. By injecting an insulative casting resin, for example, an epoxy resin, into the transformer case in this state, the primary coil 3, the secondary coil 8 and the choke coil 2 are integrally molded in the transformer case 7. Then, the common U-shaped core 10 is inserted into the primary coil 3 and the secondary coil 8 from the outside of the transformer case 7, and the U-shaped core 16 is inserted into the choke coil 2 side. As shown
A flyback transformer 1 incorporating the choke coil 2 is formed.

Then, by mounting the flyback transformer 1 on the circuit board, the flyback transformer 1 and the choke coil 2 can be connected to the high-voltage generating circuit.

According to this embodiment, since the flyback transformer 1 is integrated by incorporating the choke coil 2, the choke coil 2 can be incorporated at the same time by simply mounting the flyback transformer 1 on the circuit board. It becomes possible to facilitate the work of incorporating the flyback transformer 1 and the choke coil 2 into the circuit board.

Further, by changing the gap 18 between the abutting end faces of the U-shaped core 16 of the choke coil 2,
The magnitude of the parallel impedance of the primary coil 3 can be adjusted. That is, increasing the gap 18 decreases the parallel impedance, and decreasing the gap increases the parallel impedance. This gap adjustment makes it possible to reduce the tolerance of the parallel impedance of the choke coil 2 and the primary coil 3.

Further, even if a low-frequency leakage magnetic field or electric field leaks from the primary coil 3 and the secondary coil 8 of the flyback transformer 1 during the circuit driving, as shown in FIG. And an electric field can be generated. Moreover, since the choke coil 2 is composed of the U-shaped core 16, the leakage magnetic field and electric field in the canceling direction can be increased. Therefore, the leakage magnetic field and electric field leaking from the primary coil 3 and the secondary coil 8 sides of the flyback transformer 1 can be effectively canceled, and unnecessary radiation (EMI (Electro Magnetic Interference) leaking from the flyback transformer).
It is possible to effectively implement countermeasures and VLMF (Very Low Magnetic Frequency) countermeasures, and it is possible to eliminate the fear of low-frequency leakage magnetic fields and electric fields affecting the human body.

It should be noted that the present invention is not limited to the above-mentioned embodiment, and various modes of implementation can be adopted.

[Effect of device]

In this invention, the choke coil is built in the transformer case,
Since the choke coil is integrated with the flyback transformer, the choke coil can be mounted on the circuit board and the circuit connection can be achieved at the same time simply by mounting the flyback transformer on the circuit board. The work of incorporating the back transformer and the choke coil into the circuit board can be easily performed. As described above, by integrally manufacturing the flyback transformer and the choke coil, the manufacturing is facilitated and the number of man-hours for assembling on the circuit board is reduced, so that the cost of the device of the high voltage generating circuit can be significantly reduced.

A U-shaped core is used for the choke coil.
By adjusting the gap between the abutting end faces of the shaped core, the tolerance of the parallel impedance between the primary coil of the flyback transformer and the choke coil can be reduced, and the performance of the high voltage generation circuit can be improved.

Further, in the choke coil, the coil winding is wound in a direction to generate a canceling magnetic field and an electric field for canceling a low frequency leakage magnetic field and an electric field leaking from the primary coil and the secondary coil of the flyback transformer, and as described above, Since the U-shaped core is used for the choke coil, its canceling magnetic field and electric field can be made to be as large as the leakage magnetic field and electric field of the primary coil and the secondary coil. The leakage magnetic field and electric field of the frequency can be effectively canceled by the canceling magnetic field and electric field generated from the choke coil. Therefore, EM, which has been a problem recently,
It is possible to effectively take measures against I and VLMF, and it is possible to eliminate the fear of a low-frequency leakage magnetic field and electric field affecting the human body.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a flyback transformer according to the present invention together with a high voltage generating circuit, FIG. 2 is an explanatory view of a U-shaped core of a choke coil which constitutes the embodiment, and FIG. FIG. 4 is a plan view showing a flyback transformer integrated with a choke coil in the example, and FIG. 4 compares the directions of generation of the canceling magnetic field and the electric field of the choke coil with the direction of the low frequency leakage magnetic field and the electric field on the flyback transformer side in the example. 5 is an explanatory view of the canceling action of the low-frequency leakage magnetic field and electric field shown in FIG. 5, FIG. 5 is a circuit diagram showing a general high voltage generating circuit of the horizontal deflection coil separation type, and FIG. 6 constitutes the high voltage generating circuit of FIG. FIG. 7 is an explanatory diagram of a state where the flyback transformer and the choke coil are separately arranged, and FIG. 7 is an explanatory diagram of an EI type core used in a conventional choke coil. 1 ... Flyback transformer, 2 ... Choke coil, 3 ...
Primary coil, 4 ... Bobbin, 5 ... E-shaped core, 5a ... Central magnetic leg, 6 ... I-shaped core, 7 ... Transformer case, 8 ... Secondary coil, 9 ... Circuit board, 10 ... U-shaped core, 11 ... Horizontal Output transistor, 12 ... Damper diode, 13 ... Resonance capacitor, 14 ... Rectifier diode, 15 ... High voltage rectifier diode, 16
... U-shaped core, 17 ... Magnetic leg, 18 ... Gap, 20 ... Coil assembly, 21 ... Spring holding member.

Claims (1)

[Scope of utility model registration request] 1. A flyback transformer used in a horizontal deflection coil separation type high voltage generating circuit having a choke coil, wherein the choke coil is wound in a direction to cancel a leakage magnetic field leaking from the flyback transformer. It is connected in parallel to the primary coil of the flyback transformer, the coil of the flyback transformer and the choke coil are accommodated in the transformer case, the choke coil is integrated with the flyback transformer, and the choke coil has the end faces of the legs. A flyback transformer comprising a pair of U-shaped cores that are fitted into each other in abutting relation, and a gap is formed between the abutting end faces of the U-shaped cores.