JP2008171880A - Transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transformer in which a surely required insulating distance between a primary coil and a secondary coil can be ensured with a simple structure without causing large scale of its external shape. <P>SOLUTION: The transformer is provided with a first bobbin 1 having a first terminal attaching portion 6 integrally formed of the end of a first cylindrical winding portion 4 having a primary coil 3 wound therearoud, and a second bobbin 2 having a second cylindrical winding 14 having the secondary coil 10 wound therearound, wherein the adjacently disposed first and second bobbins form a closed magnetic passage together with cores 7, 18 made of a magnetic material. In the transformer, a portion as at least the external circumference of the primary coil 3 of the first bobbin 1 and other than a protruding portion of a mounting end portion 5b of a terminal 5 is covered with an insulating layer 8. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a transformer suitable for use in a high voltage output from a secondary coil, such as an inverter transformer for lighting a cold cathode tube.

  A liquid crystal display, which is a kind of display device, incorporates a plurality of cold cathode tubes as light sources for screen irradiation, and an inverter transformer is used for discharging and lighting these cold cathode tubes. This inverter transformer boosts the input voltage to the primary coil to 1000 to 2000 V in the secondary coil and outputs it to the cold cathode tube.

  By the way, in this type of conventional inverter transformer, a DC voltage of 24V converted from an input voltage of 100V in the transmission circuit is input to the primary coil. Since an auxiliary power source is required, there is a disadvantage that it is inferior in efficiency and economy.

For this reason, in recent years, a power supply configuration in which the auxiliary power supply is omitted is being adopted by rectifying an input voltage of 100 V and directly inputting it to the one coil.
However, when such a configuration is adopted, a longer insulation distance (creeping distance) is ensured between the primary coil and the secondary coil than the conventional one for safety standards, and insulation between each other is ensured. It will be required to secure.

Thus, for example, in Patent Document 1 below, a terminal block in which a flange that divides primary and secondary is formed on the outer periphery of a hollow winding drum portion, and terminals are implanted in the flanges at both ends of the winding drum portion, respectively. A transformer in which a primary and secondary coil is wound around the outer periphery of the winding body is molded with an insulating resin in advance, and a core is incorporated into the molded body. ing.
JP-A-2005-286188

However, in the transformer shown in Patent Document 1, since the entire transformer excluding the terminals is molded with an insulating resin, the entire transformer is increased in size. There was a problem of going backwards.
In addition, a large amount of resin material is required to perform the molding, and there is a problem that the cost is inferior.

  The present invention has been made in view of such circumstances, and ensures an insulation distance between a primary coil and a secondary coil that is reliably required by a simple structure without causing an increase in size of the outer shape. It is an object of the present invention to provide a transformer that can be used.

In order to solve the above-mentioned problem, the invention described in claim 1 is made of a material having electrical insulation, and the first end portion of the cylindrical first winding portion around which the primary coil is wound is provided. A terminal mounting part is integrally formed, and an end of the primary coil is connected to the first terminal mounting part and a terminal in which a mounting end protrudes from the first terminal mounting part is internally provided. The first bobbin includes a first bobbin and a second bobbin made of a material having electrical insulation and having a cylindrical second winding portion around which a secondary coil is wound, In the transformer in which the second bobbin forms a closed magnetic path with a core made of a magnetic material,
The outer periphery of at least the primary coil of the first bobbin and a portion excluding the protruding portion of the mounting end are covered with an insulating layer.

  According to a second aspect of the present invention, in the first aspect of the invention, the first bobbin and the insulating layer are each formed of a synthetic resin, and the second bobbin is formed of the insulating layer. It is characterized in that it is molded integrally.

  Furthermore, the invention according to claim 3 is the invention according to claim 1 or 2, wherein the insulating layer has a covering portion covering an outer periphery of the first terminal mounting portion, and an end portion of the covering portion. The length dimension up to the shortest distance from the core to the end part plus the shortest distance from the end part to the live part of the primary coil covered by the covering part is safe. It is set so that it may become more than the insulation distance requested | required above.

  According to the transformer in any one of Claims 1-3, since at least the outer periphery of the primary coil arrange | positioned adjacent to the secondary coil is covered with the insulating layer, the primary coil and the secondary coil The insulation distance is a distance from the mounting end of the terminal connected to the primary coil and protruding from the first terminal mounting portion to the secondary coil (or core). Therefore, the insulation distance between the primary coil and the secondary coil required by the safety standard can be ensured without increasing the size of the outer shape.

  According to the second aspect of the present invention, after the first bobbin is formed by injection molding and the primary coil is wound around the first winding portion, at least the first bobbin When forming the insulating layer only on the outer periphery of the primary coil, if the second bobbin is also integrally formed at the same time, the first and second bobbins can be integrated easily and reliably, and the entire transformer This manufacturing process can also be simplified.

  In the invention of claim 3, the length of the insulating layer is formed up to the outer periphery of the first terminal mounting portion, and the length of the covering portion covering the first terminal mounting portion is as follows: The length obtained by adding the shortest distance from the core to the end and the shortest distance from the end to the live part of the primary coil covered by the covering is equal to or greater than the insulation distance required for safety. Therefore, not only the insulation distance between the secondary coil and the mounting end protruding from the primary terminal mounting portion on the primary coil side, but also the back surface of the covering portion from the core. As for the insulation distance from the side to the live part of the primary coil, it is possible to ensure the distance required for safety standards.

(First embodiment)
1 to 6 show a first embodiment in which a transformer according to the present invention is applied to an inverter transformer for lighting a cold cathode tube as a backlight of an LCD. In this inverter transformer, a bobbin is a first embodiment. The bobbin 1 and the second bobbin 2 are divided.

  As shown in FIG. 2, the first bobbin 1 is a rectangular tube-shaped first coil in which a conducting wire for forming a primary coil 3 is wound between flange portions 4c formed at both ends in the axial direction. A substantially rectangular plate-shaped first in which a winding portion 4 and a terminal 5 formed on one end side in the axial direction of the first winding portion 4 and connected to the end portion of the conducting wire of the primary coil 3 are implanted. The terminal mounting portion 6 is integrally molded of an electrically insulating synthetic resin.

  Here, when the first bobbin 1 is injection-molded, the terminal 5 is inserted into the inside at the same time, and the bent one end portion 5a is used as the first winding portion in the first terminal mounting portion 6. 4 is protruded from the side surface in the vicinity of 4, and the other end portion is disposed as a mounting end portion 5b so as to protrude from the outer peripheral surface 6a facing the first winding portion 4. And the edge part of the conducting wire which forms the primary coil 3 is entangled and connected to the one end part 5a.

  In addition, a hole 4a through which an I-type first core 7 (see FIG. 5) made of a ferrite core is inserted is formed in the first winding portion 4, and the hole 4a is formed as shown in FIG. In the state shown in FIG. 2, the first winding portion 4 is opened at both ends.

  As shown in FIG. 3, the first bobbin 1 after the primary coil 3 is wound is electrically insulated from the secondary coil 10 wound on the second bobbin 2 described later. The insulating layer 8 is formed by a resin mold. This insulating layer 8 is formed in a range that covers the entire circumference of the primary coil 3 and the inside of the hole portion 4a, and further covers about 2/3 of the total length of the first terminal mounting portion 6 in the axial direction. The insulating layer 8 can be formed by transfer molding or injection molding.

  And the coating | coated part 9 which covers the 1st terminal mounting part 6 part of this insulating layer 8 is further comprised by the core accommodating part 11 and the insulating part 12 sequentially toward the said axial direction from the primary coil 3 side. . Here, the core housing portion 11 is formed in a flat plate shape having a thickness that is continuous with the inner wall of the hole 4 a of the first winding portion 3 and a width that includes the one end portion 5 a of the terminal 5. ing. Further, a pair of wall portions 11 a that are continuous with both side walls 4 b of the hole portion 4 a are erected in the core housing portion 11.

  The insulating portion 12 is formed in a prismatic shape having a width dimension equal to that of the core housing section 11 and a width dimension slightly larger than the thickness dimension of the primary coil 3. Thereby, between the core accommodating part 11 and the insulating part 12, the locking wall part 13 for locking the edge part 7a of the 1st core 7 is formed.

  Further, as shown in FIG. 6, the insulating portion 12 has an axial length of the outer peripheral surface 6 a of the first terminal mounting portion 6 from which the mounting end portion 5 b protrudes from the end portion of the core housing portion 11. Is formed to ½ of the length a.

  On the other hand, as shown in FIG. 4, the second bobbin 2 has a rectangular tube-like second shape in which a conducting wire for forming the secondary coil 10 is wound between flange portions 14c formed at both ends in the axial direction. The second winding portion 14 and a second plate-like second member in which a terminal 15 to which the end portion of the conducting wire of the secondary coil 10 is connected is arranged on one end side in the axial direction of the second winding portion 14. Similarly, the terminal mounting portion 16 is integrally formed of a synthetic resin having electrical insulation. The terminal 15 is also molded inside at the same time when the second bobbin 2 is injection-molded, and the mounting end portion 15a is projected from the outer peripheral surface 16a facing the second winding portion 14. Has been.

  The second winding portion 14 has a cross-sectional shape substantially the same as that of the first winding portion 4, and the I-type first core 7 communicates with the hole 4 a inside. A hole 14a to be inserted is formed. A plurality of partition plates 17 for preventing creeping discharge in the high-voltage secondary coil 10 are integrally formed on the outer peripheral portion at equal intervals in the axial direction. On the other hand, the surface of the second terminal mounting portion 16 is formed in a flat plate shape that is continuous with the inner wall of the hole portion 14a, and a pair of wall portions 16b are erected at positions that are continuous with both side walls 14b of the hole portion 14a. Has been.

  As shown in FIG. 5, the first and second bobbins 1 and 2 are brought into contact with the ends of the first and second winding portions 4 and 14 and are separately bonded with an adhesive or not shown. It is connected integrally through the part. Further, the I-type first core 7 is inserted into the holes 4 a and 14 a of the first and second winding portions 4 and 14.

  The first core 7 is formed in a rectangular plate shape that can be loosely inserted into the holes 4a and 14a, and the wall 16b and the first bobbin that are erected on the second terminal mounting portion 16 Both sides are guided by a wall portion 11a formed in one core housing portion 11, and the tip portion 7a is positioned by abutting against a locking wall portion 13 formed in the covering portion 8 of the first bobbin 1. Has been.

  Further, as shown in FIG. 1, a second core 18 made of a ferrite core is provided on the outer periphery of the first and second bobbins 1 and 2. The second core 18 is a rectangular frame member having a rectangular opening 18a formed at the center, and the side portions 18b facing in the axial direction are on the core housing portion 11 of the first bobbin 1 and The second bobbin has a length dimension that abuts on the upper surface of the end of the first core 7 exposed on the terminal mounting portion 16 of the bobbin.

  The second core 18 is formed to have a width dimension that surrounds the primary coil 3 and the secondary coil 10 located in the opening 18a with the side portions 18b and 18c through a slight gap. As a result, a closed magnetic path is formed by the first and second cores 7 and 18.

  According to the transformer configured as described above, the outer periphery of the primary coil 3 disposed adjacent to the secondary coil 10 and the connection portion between the primary coil 3 and the end 5a are electrically connected from the secondary coil 10. Since it is covered with the insulating layer 8 to insulate, as shown in FIG. 6, the insulation distance between the live part of the primary coil 3 on the low voltage side and the second core 18 which is the secondary high voltage structure is A distance L (= a) from the mounting end 5b of the terminal 5 that is connected to the primary coil 3 and protrudes from the outer peripheral surface 6a of the first terminal mounting portion 6 to the second core 18 is obtained.

  Therefore, the insulation distance between the primary coil 3 and the secondary coil 10 (or the second core 18) required by the safety standard can be reduced without increasing the size of the outer shape as in the conventional transformer described above. It can be secured easily.

  In addition, in this transformer, an insulating layer 8 that covers the primary coil 3 is further formed up to the outer periphery of the first terminal mounting portion 6, and a core housing portion is formed on the covering portion 9 that covers the first terminal mounting portion 6. 11 and the insulating part 12, and the length dimension in the axial direction of the insulating part 12 is set to 1 of the length dimension a from the end of the core housing part 11 to the outer peripheral surface 6 a of the first terminal mounting part 6. / 2.

For this reason, the terminal 5 connected to the primary coil 3 from the end 12a to the shortest distance from the second core 18 to the end 12a in the axial direction of the covering 12 through the back side of the covering 12 is provided. The insulation distance L ₁ including the distance to the end portion 5a (the live part) can also be made longer than the insulation distance L (= a) required for safety.

As a result, not only the insulation distance L between the second core 18 and the mounting end portion 5b of the terminal 5 protruding from the first terminal mounting portion 6 on the primary coil 3 side, but also the covering portion from the second core 18 As for the insulation distance L ₁ that reaches the end portion 5a of the terminal 5 through the rear surface side of 12, the distance required in safety standards can be ensured.

(Second Embodiment)
FIG. 7 shows a second embodiment of a transformer according to the present invention. The same components as those shown in FIGS. 1 to 6 are denoted by the same reference numerals, and the description thereof will be simplified.
In this transformer, the primary coil 3 is wound around the first winding portion 4 of the first bobbin 1 shown in FIG. 3, and the outer periphery of the primary coil 3 and the first terminal mounting portion 6 is further wound. When the insulating layer 8 is formed, the entire second bobbin 2 is integrally formed by injection molding. At this time, the terminal 15 is also inserted into the second terminal mounting portion 16 of the second bobbin 2 at the same time.

  Thereby, the 1st bobbin 1 and the 2nd bobbin 2 are connected integrally. Then, the secondary coil 10 is similarly wound around the second winding portion 14 of the second bobbin 2 formed integrally with the insulating layer 8 in this way, and the first core 7 and the first core 7 The transformer of this embodiment is completed by incorporating the two cores 18.

  Therefore, according to the transformer of the present embodiment, after the first bobbin 1 is formed by injection molding and the primary coil 3 is wound around the first winding portion 4, the primary of the first bobbin 1 is When the insulating layer 8 is formed on the entire circumference of the coil 3 and a part of the outer circumference of the first terminal mounting portion 6, the second bobbin 2 is also integrally molded at the same time, so that the first and second bobbins The integration of 1 and 2 can be performed easily and reliably, and the manufacturing process of the entire transformer can be simplified.

  In the first and second embodiments, the first and second terminal mounting portions 6 and 16 are the first and second windings as the first and second bobbins 1 and 2, respectively. Formed at one end in the axial direction of the wire portions 4 and 14, the mounting end portions 5 b and 15 a of the terminals 5 and 15 project from the outer peripheral surfaces 6 a and 16 a facing the first or second winding portions 4 and 14. However, the present invention is not limited to this, and the terminal mounting portion is formed so as to have a longitudinal direction in a direction orthogonal to the axial direction, and the longitudinal direction front end surface is used to The present invention can be similarly applied to bobbins having various shapes such as a terminal whose end is protruded.

  Moreover, although the said transformer showed what arranged the 1st set of primary coil 3 and the secondary coil 10 adjacent to the axial direction, not only this but the axial direction both ends of the primary coil, By arranging the secondary coils respectively, a transformer having two sets of secondary coils for lighting the two cold-cathode tubes simultaneously or differentially, and further, a plurality of primary coils and a plurality of primary coils The present invention can also be applied to various transformers combined with secondary coils.

1A and 1B show a first embodiment of a transformer according to the present invention, in which FIG. 1A is an overall plan view, FIG. 1B is a left side view, and FIG. FIGS. 1A and 1B show the first bobbin of FIG. 1 before an insulating layer is formed, in which FIG. 1A is a plan view and FIG. 1B is a right side view thereof. FIGS. 1A and 1B show a first bobbin of FIG. 1, in which FIG. 1A is a plan view, FIG. 1B is a right side view thereof, and FIG. FIGS. 2A and 2B show a second bobbin of FIG. 1, wherein FIG. 1A is a plan view and FIG. 1B is a left side view thereof. It is a top view which shows the assembly state of the 1st and 2nd bobbin and a 1st core. It is the elements on larger scale which show the insulation distance in the trans | transformer of FIG. FIG. 3 is a plan view corresponding to FIG. 2, showing a second embodiment of a transformer according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st bobbin 2 2nd bobbin 3 Primary coil 4 1st coil | winding part 4a, 14a Hole 5, 15 Terminal 5b, 15a Mounting end part 6 1st terminal mounting part 6a, 16a Outer peripheral surface 7 1st 1 core 8 insulating layer 9 covering portion 10 secondary coil 14 second winding portion 16 second terminal mounting portion 18 second core

Claims (3)

A first terminal mounting portion is formed integrally with an end portion of a cylindrical first winding portion around which a primary coil is wound, and the first terminal mounting portion is formed of an electrically insulating material. The first bobbin in which the end of the primary coil is connected and the terminal whose mounting end protrudes from the first terminal mounting portion is housed, and is made of a material having electrical insulation. And a second bobbin having a cylindrical second winding portion around which a coil is wound, and the first and second bobbins arranged adjacent to each other have a closed magnetic circuit formed by a core made of a magnetic material. In
A transformer characterized in that at least an outer periphery of the primary coil of the first bobbin and a portion excluding the protruding portion of the mounting end are covered with an insulating layer.   2. The transformer according to claim 1, wherein the first bobbin and the insulating layer are each formed of a synthetic resin, and the second bobbin is formed integrally with the insulating layer.   The insulating layer has a covering portion that covers the outer periphery of the first terminal mounting portion, and a length dimension from the core to the end portion is the shortest distance from the core to the end portion. The length including the shortest distance from the active portion of the primary coil covered by the covering portion to the active portion is set to be equal to or longer than the insulation distance required for safety. The transformer according to 1 or 2.

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