JP2001176741A - Flyback transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable flyback transformer which can reduce the temperature rise of its primary coil as much as possible. SOLUTION: This flyback transformer is constituted, in such a way that a hole section 3 is formed inside a primary coil bobbin 2, and a plurality of rids 5 are provided on the inner peripheral surface of the hole section 3. Then a core 1 is inserted into the space inside the ribs 5, so as to form air layers 7 between the hole section 3 and core 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flyback transformer for supplying a high voltage to a television receiver or a CRT of a color display, and more particularly to a structure of a primary coil bobbin and a core thereof.

[0002]

2. Description of the Related Art FIG. 10 is a longitudinal sectional view of a coil portion in a conventional flyback transformer, and FIG. 11 is a plan view of the coil portion. As shown in these figures, the core 1 is inserted into the cylindrical hole 3 formed in the primary coil bobbin 2 and the core 1 and the hole 3 are bonded with an adhesive 4 to thereby obtain the core. 1 was fixed to the primary coil bobbin 2.

[0003]

The flyback transformer supplies a power supply voltage for other circuits in addition to the high-voltage output, and the state of temperature rise changes depending on the level of these outputs. In order to support recent high-quality screens, the driving frequency also increases, which increases the core loss and increases the temperature of the flyback transformer.

[0004] The reliability of the flyback transformer depends on the heat-resistant temperature of the insulating material that insulates the coil. Therefore, when the coil is used at a low temperature, the reliability is improved accordingly. On the other hand, in recent years, price competition is severe, and it is desirable to reduce the size of particularly expensive cores as much as possible. However, when the diameter of the core is reduced, there is a problem that the magnetic flux density of the core increases and the temperature rise increases.

In the conventional flyback transformer, since there is almost no gap between the hole 3 of the primary coil bobbin 2 and the core 1 and almost all of the gap is filled with the adhesive 4, the coil is wound around the coil bobbin 2. The temperature of the primary coil (not shown) rises in almost the same state as the core 1. Therefore, as described above, when the diameter of the core 1 is reduced to reduce the cost, the magnetic flux density increases, the temperature of the core 1 rises sharply, and the primary coil also has almost the same temperature as the core 1, and the A problem arises in terms of points.

An object of the present invention is to provide a highly reliable flyback transformer which can eliminate such disadvantages of the prior art and can minimize a rise in the temperature of the primary coil as much as possible.

[0007]

In order to achieve the above object, a first means of the present invention is to form a hole inside a primary coil bobbin around which a primary coil is wound, and to form a hole inside the hole. In a flyback transformer that inserts a part of the core,
An air layer for heat insulation is formed between the hole and the insertion portion of the core.

In order to achieve the above object, a second means of the present invention is the first means, wherein a plurality of protrusions are provided at predetermined intervals on an inner peripheral surface of the hole, and the plurality of protrusions are provided. An air layer is formed between the hole and the insertion portion of the core by inserting a core inside the hole.

In order to achieve the above object, a third means of the present invention is the first means, wherein an inner cylindrical portion is provided at a predetermined interval radially inward of the hole, and the inner tube is provided with the hole. The connection between the inner cylinders is integrally connected by a connection rib, an air layer is formed between the hole and the inner cylinder, and a part of the core is inserted inside the inner cylinder. Is what you do.

According to a fourth aspect of the present invention, in the first aspect, a plurality of projections are provided on an outer periphery of the insertion part of the core, and the insertion part of the core is formed in the hole part. , An air layer is formed between the hole and the insertion portion of the core.

According to a fifth aspect of the present invention, in the second or fourth aspect, the protrusion is a rib extending along the insertion of the core. It is assumed that.

According to a sixth aspect of the present invention, in order to achieve the above object, in any one of the first to fifth aspects, an air layer penetrates in an axial direction of the hole. It is characterized by the following.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The first to fourth means of the present invention have the above-mentioned structure, and an air layer for heat insulation is provided between a core and a primary coil bobbin.
Even if the core temperature rises, the primary coil is not affected by the core temperature rise, so that a long-life and highly reliable flyback transformer can be provided.

According to a fifth aspect of the present invention, as described above, the protrusion formed on the coil bobbin or the core is a rib extending along the insertion of the core.
In addition, the protrusion is not crushed, and the formation of the air layer by the protrusion is reliable.

According to the sixth aspect of the present invention, since the air layer penetrates along the axial direction of the hole as described above, air flows in the air layer, and therefore, the air flows from the core to the primary coil. The effect of temperature can be reliably reduced, and a highly reliable flyback transformer can be provided.

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a coil portion in the flyback transformer according to the first embodiment, FIG. 2 is a plan view of the coil portion, FIG. 3 is a longitudinal sectional view of a primary coil bobbin used in the flyback transformer, and FIG. FIG. 3 is a plan view of the coil bobbin.

A plurality of ribs 5 linearly extending in the insertion direction of the core 1 are integrally formed at predetermined intervals on the inner surface of the cylindrical hole 3 formed in the primary coil bobbin 2. Have been. The upper end and the lower end of the rib 5 are provided with an inclined surface 6 or roundness for smooth insertion of the core 1.

The core 1 is inserted into the inside of the plurality of ribs 5 from above and below, and their ends contact each other. The core 1 and the ribs 5 are bonded with an adhesive 4. With the core 1 fixed to the coil bobbin 2 in this way, as shown in FIG. 2, the core 1 penetrated between the core 1 and the hole 3 along the axial direction of the hole 3 (perpendicular to the paper). Ventilation path (air layer) 7
Are formed in a plurality in the circumferential direction of the core 1.

FIG. 5 is a plan view showing a cross section of a part of a coil portion in a flyback transformer according to a second embodiment.
FIG. 6 is a longitudinal sectional view of a primary coil bobbin used for the flyback transformer.

An inner cylinder 8 is provided at a predetermined interval inside the hole 3 formed in the primary coil bobbin 2, and a plurality of the inner cylinders 8 are formed in the circumferential direction as shown in FIG. It is formed integrally with the coil bobbin 2 by the connecting rib 9, and the hole 3 is formed.
A ventilation passage 7 (air layer) penetrating along the axial direction of the hole 3 is formed between the inner cylindrical portion 8 and the inner cylindrical portion 8. As shown in FIG. 5, the core 1 is inserted inside the inner cylindrical portion 8, and the core 1 is
Thus, it is fixed to the inner cylindrical portion 8 of the coil bobbin 2.

FIG. 7 is a longitudinal sectional view of a coil portion in a flyback transformer according to a third embodiment, and FIG. 6 is a transverse sectional view of a core used in the flyback transformer. In this embodiment, a plurality of ribs 10 are provided at predetermined intervals on the outer peripheral surface near the distal end portion of core 1 inserted into coil bobbin 2.
Is provided. By inserting the tip with the rib 10 into the hole 3 of the coil bobbin 2, a ventilation path 7 (air layer) penetrating along the axial direction of the hole 3 is formed between the core 1 and the hole 3. ing. As shown in FIG. 7, the tips of the cores 1 abut each other, and the ribs 10 of the core 1 are fixed to the coil bobbin 2 by the adhesive 4.

Although not shown in FIGS. 1, 6 and 7, a primary coil is wound around the outer periphery of the coil bobbin 2.

[0023]

FIG. 9 is a temperature rise characteristic diagram of each part of the flyback transformer. The horizontal axis indicates the core cross-sectional area, and the vertical axis indicates the temperature increase Δ.
T is shown. A line a in the figure is a core temperature rise curve, a line b is a coil temperature rise curve of the conventional flyback transformer shown in FIGS. 10 and 9, and a line c is the first embodiment of the present invention shown in FIGS. It is a coil temperature rise curve of the flyback transformer concerning an embodiment. The temperature rise curve a of the core is the same for the conventional flyback transformer and the flyback transformer according to the embodiment of the present invention.

As is apparent from this figure, as the core cross-sectional area becomes smaller, the core temperature rises as shown by the line a. While the coil temperature of the conventional flyback transformer rises substantially along the rise of the core temperature as shown by the line b, the flyback transformer of the present invention affects the rise of the core temperature as shown by the line c. However, the coil temperature is almost constant. This effect can be obtained similarly in the flyback transformer according to the second and third embodiments.

[0025] The first to fourth means of the present invention have the above-described structure, and since an air layer for heat insulation is provided between the core and the primary coil bobbin, the temperature of the core increases. Therefore, the primary coil is not affected by the temperature rise of the core, so that a long-life and highly reliable flyback transformer can be provided.

According to the fifth aspect of the present invention, since the protrusion formed on the coil bobbin or the core as shown in FIG. 8 is a rib extending along the insertion of the core, the core can be inserted smoothly. In addition, the protrusion is not crushed, and the formation of the air layer by the protrusion is reliable.

According to the sixth aspect of the present invention, since the air layer penetrates in the axial direction of the hole as described above, air flows in the air layer, and therefore, the air flows from the core to the primary coil. The effect of temperature can be reliably reduced, and a highly reliable flyback transformer can be provided.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a coil unit in a flyback transformer according to a first embodiment of the present invention.

FIG. 2 is a plan view of the coil unit.

FIG. 3 is a longitudinal sectional view of a primary coil bobbin used for the flyback transformer.

FIG. 4 is a plan view of the coil bobbin.

FIG. 5 is a plan view showing a cross section of a part of a coil unit in a flyback transformer according to a second embodiment of the present invention.

FIG. 6 is a longitudinal sectional view of a primary coil bobbin used for the flyback transformer.

FIG. 7 is a longitudinal sectional view of a coil unit in a flyback transformer according to a third embodiment of the present invention.

FIG. 8 is a cross-sectional view of a core used for the flyback transformer.

FIG. 9 is a temperature rise characteristic diagram of each part of the present invention and a conventional flyback transformer.

FIG. 10 is a cross-sectional view of a coil portion in a conventional flyback transformer.

FIG. 11 is a side view of the coil unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Core 2 Primary coil bobbin 3 Hole part 4 Adhesive 5 Rib 6 Inclined surface 7 Ventilation path (air layer) 8 Inner cylinder part 9 Connecting rib 10 Rib

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshihiko Sugawara 1 Kitano, Makino, Mizusawa City, Iwate Prefecture Inside Hitachi Media Electronics Co., Ltd. (72) Inventor Mitsuhiro Sugano 1 Kitano Masaki, Mizusawa City, Iwate Hitachi Within Media Electronics (72) Inventor Teruaki Sato 1 Kitano, Makino, Mizusawa-shi, Iwate F-term within Hitachi Media Electronics Co., Ltd. (reference) 5E070 AA13 FA01 FB06 FC06

Claims (6)

[Claims] 1. A flyback transformer in which a hole is formed inside a primary coil bobbin around which a primary coil is wound and a part of a core is inserted inside the hole, wherein the hole and a core insertion portion are provided. A flyback transformer characterized by forming an air layer for heat insulation between the two. 2. The flyback transformer according to claim 1, wherein a plurality of protrusions are provided at predetermined intervals on an inner peripheral surface of the hole, and a core is inserted inside the protrusions. A flyback transformer, wherein an air layer is formed between the hole and the insertion portion of the core. 3. The flyback transformer according to claim 1, wherein an inner cylindrical portion is provided at a predetermined interval radially inward of the hole, and the hole and the inner cylindrical portion are integrally connected by a connecting rib. A flyback transformer, wherein an air layer is formed between the hole portion and the inner cylinder portion, and a part of the core is inserted inside the inner cylinder portion. 4. The flyback transformer according to claim 1, wherein a plurality of holes are provided on an outer periphery of the insertion portion of the core,
A flyback transformer, wherein an air space is formed between the hole and the insertion portion of the core by inserting the insertion portion of the core into the hole. 5. The flyback transformer according to claim 2, wherein the protrusion is a rib extending along the insertion of the core. 6. The flyback transformer according to claim 1, wherein said air layer penetrates in an axial direction of said hole.