JP6589588B2 - Pulse transformer - Google Patents

Description

  The present invention relates to a pulse transformer used for, for example, an application for transmitting a pulse signal through a LAN cable or the like.

  When connecting a device such as a personal computer to a network such as a LAN or a telephone network, it is necessary to protect the device from ESD (ElectroStatic Discharge) and high voltage entering through a cable. Therefore, a pulse transformer is used as a connector constituting the connection point between the cable and the device.

  A conventional pulse transformer is made by winding a primary coil and a secondary coil around a donut-shaped magnetic core (toroidal core), and only the AC component (pulse) of the voltage applied to the primary coil is secondary. It has the property of transmitting to the coil. Since the direct current component is not transmitted to the secondary coil, the pulse transformer can block ESD and high voltage.

  In recent years, pulse transformers are also required to be miniaturized and surface-mounted. For this reason, an example in which a drum core is used instead of the toroidal core has appeared. Such a pulse transformer is referred to as a surface mount type pulse transformer, and an example thereof is disclosed in Patent Document 1.

  By the way, the network speed of Ethernet (registered trademark) (Ethernet (registered trademark)) from 10BASE-T of 10Mbps (bits per second) to 10 times 100Mbps 100BASE-TX has become widespread, and now 1Gbps 1000BASE -T is popular. In addition, 10GBASE-T (10 Gigabit Ethernet (registered trademark) (10GbE)) has been newly standardized.

  Therefore, there is a demand for a pulse transformer having a small insertion loss (insertion loss) particularly at a high frequency. If the insertion loss is small, the signal attenuation amount is small, and if the attenuation amount of the high frequency component is small, a high-speed data signal can be accurately sent to a long (long) distance. However, in the conventional pulse transformer, it has been difficult to satisfy the reduction of insertion loss at high frequency with particularly strict standards.

JP 2009-21558 A

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a pulse transformer capable of reducing insertion loss at a high frequency with a particularly strict standard.

  As a result of intensive studies on the pulse transformer, the inventors of the present invention have a winding density lower than that of the winding region in the middle of the normal coil winding region in which the wires are closely attached to each other and wound around the core portion. It has been newly found out that the insertion loss can be reduced by providing the region, and the present invention has been completed.

That is, the pulse transformer according to the present invention is
A pulse transformer having a winding core part and a coil part in which a wire is wound around the winding core part,
The coil portion is
A first normal winding region in which the wires are in close contact with each other and wound around the core portion;
A second continuous winding region formed of a wire continuous with the wire constituting the first normal winding region and wound around the core portion in close contact with each other;
A low-density winding region formed between the first normal winding region and the second normal winding region along the winding axis of the winding core portion and having a low winding density of the wire along the winding shaft And having.

  In the pulse transformer according to the present invention, the reason why the insertion loss can be reduced in the high frequency region is not necessarily clear, but at the boundary between the low density winding region and the normal winding region, the winding of the wire is not It is thought that this is because leakage flux is reduced due to unraveling (for example, the wire located in the second layer falls to the first layer).

  In the pulse transformer of the present invention, since the insertion loss in the high frequency region can be reduced, the amount of signal attenuation at the high frequency is reduced, and a high-speed data signal can be sent accurately over a long (long) distance.

  Preferably, the surface of the core part is exposed in the low density winding region. With this configuration, the effect of reducing the insertion loss in the high frequency region can be increased.

  Preferably, the gap width in the winding axis direction at which the surface of the winding core part is exposed is equal to or greater than the wire diameter of the wire. With this configuration, the effect of reducing the insertion loss in the high frequency region can be increased.

  Preferably, the length of the low-density winding region in the winding axis direction is twice or more the wire diameter of the wire. With this configuration, the effect of reducing the insertion loss in the high frequency region can be increased.

  Preferably, some of the plurality of wires constitute the first layer of the coil portion, and the other remaining wires constitute the second layer of the coil portion. With this configuration, the effect of reducing the insertion loss in the high frequency region can be increased.

  Preferably, the wire in the first layer and the wire in the second layer are wound in opposite directions. With this configuration, the effect of reducing the insertion loss in the high frequency region can be increased.

  Preferably, the length in the winding axis direction of each of the first normal winding region and the second normal winding region is a length in which the wire is wound twice or more.

  The coil portion is formed of a wire continuous with the wire constituting the second normal winding region, and further includes a third normal winding region wound around the core portion in close contact with each other. A low density winding region similar to the low density winding region is formed between the third normal winding region and the second normal winding region along the winding axis direction. Also good.

  Preferably, the length of the third normal winding region in the winding axis direction is a length obtained by winding the wire into two or more turns.

  The coil portion further includes a fourth normal winding region, and the low density is provided between the fourth normal winding region and the third normal winding region along the winding axis direction. You may have further the low density winding area | region similar to a winding area | region. Hereinafter, similarly, the fifth and subsequent normal winding regions may be formed through the low-density winding region.

FIG. 1 is a perspective view of a pulse transformer according to an embodiment of the present invention. 2A is a front view of the pulse transformer shown in FIG. 2B is a rear view of the pulse transformer shown in FIG. FIG. 2C is a side view of the pulse transformer shown in FIG. FIG. 2D is a plan view of the pulse transformer shown in FIG. 2E is a bottom view of the pulse transformer shown in FIG. FIG. 3 is a schematic half-sectional view of a coil portion wound around the core portion of the transformer shown in FIG. FIG. 4 is an equivalent circuit diagram of the transformer shown in FIG. FIG. 5 is a perspective view of a pulse transformer according to another embodiment of the present invention. FIG. 6 is a graph showing the effect of reducing the insertion loss of the pulse transformer according to the embodiment of the present invention.

  Hereinafter, the present invention will be described based on embodiments shown in the drawings.

First Embodiment As shown in FIG. 1, a pulse transformer according to an embodiment of the present invention is composed of a coil component 10 of a surface mount type. The coil component 10 includes a first core 20 that is a drum-type core, a plate-shaped second core 30, and a coil portion 40 that is wound around the core portion 22 of the first core 20.

  In the description of the coil component 10, the direction parallel to the winding axis of the core portion 22 of the first core 20 in the plane parallel to the mounting surface on which the coil component 10 is mounted is the same as the X axis and the X axis. The direction perpendicular to the X axis in the plane parallel to the Y axis is the Y axis direction, and the normal direction of the mounting surface is the Z axis direction.

  The outer dimensions of the coil component 10 are, for example, (width 3.2 mm × height 2.8 mm × depth 3.2 mm), but the size of the coil component 10 is not limited to this.

  As shown in FIG. 2A, which is a front view of the coil component 10, the core of the coil component 10 is configured by combining the first core 20 and the second core 30. The first core 20 includes a rod-shaped core portion 22 and a pair of flange portions 24 and 24 as a pair of core end portions provided at both ends of the core portion 22.

  As shown in FIGS. 1 and 2A, the outer shape of the flange portion 24 is a substantially rectangular parallelepiped, and the pair of flange portions 24 are disposed so as to be substantially parallel to each other with a predetermined interval in the X-axis direction. ing. The winding core part 22 is connected to the center part of each surface facing each other in the pair of collar parts 24, and connects the pair of collar parts 24. Although the cross-sectional shape of the core part 22 is a rectangle in this embodiment, a circular shape may be sufficient and the cross-sectional shape is not specifically limited.

  The second core 30 is a plate-like core, and the outer shape of the second core 30 is a substantially rectangular parallelepiped whose side in the Z-axis direction is the shortest side. As shown in FIG. 2E, the second core 30 has a substantially rectangular shape that is long in the X-axis direction when viewed from the normal direction (Z-axis direction) of the upper surface 32, but may be a square or other shapes. As shown in FIG. 2A, the upper surface 32 of the second core 30 located at both ends in the X-axis direction faces the bottom surface 24a of the flange 24, and an adhesive such as a thermosetting resin is applied to the bottom surface 24a. It is fixed by. Thereby, the second core 30 forms a magnetic path continuous with the first core 20.

  As shown in FIGS. 1 to 2E, terminal portions 51 to 56 are provided on the flange portions 24 of the first core 20. The terminal portions 51 to 56 are made of metal fittings having a substantially L-shaped outer shape, and at least a part thereof is provided on the installation surface 24 b of the flange portion 24. The installation surface 24b of the flange 24 is an upper surface in the Z-axis direction opposite to the bottom surface 24a facing the upper surface 32 of the second core 30.

  As shown in FIG. 2D when the coil component 10 is viewed from the upper side of the Z-axis, the three terminal portions 51 to 53 are provided on the one flange portion 24, and the other three terminal portions 54 to 56 are on the other side. Is provided on the heel part 24. The interval between the adjacent terminal portions is not equal, and the interval between the terminal portion 52 and the terminal portion 53 is designed to be wider than the interval between the terminal portion 51 and the terminal portion 52, and the interval between the terminal portion 54 and the terminal portion 55. Is designed to be wider than the distance between the terminal portion 55 and the terminal portion 56.

  As shown in FIG. 2A, a coil portion 40 is formed on the core portion 22 of the first core 20. As shown in FIG. 2D and FIG. 4 which is an equivalent circuit diagram, the coil unit 40 is configured by four wires 41 to 44. The wires 41 to 44 are configured by, for example, coated conductors, and have a configuration in which a core material made of a good conductor is covered with an insulating coating film, and is wound around the core portion 22 in a two-layer structure. Yes.

  As shown in FIG. 3, the wires 42 and 44 are wound around the core portion 22 with a normal bifilar to form a first layer, and the wires 41 and 43 are wound around the core portion 22 with a normal bifilar and wound into a second layer. Configure. In addition, in the present embodiment, the first-layer wires 42 and 44 and the second-layer wires 41 and 43 are wound in opposite directions. Further, the number of windings of the wires 41 to 44 is the same, but may be different.

  In this embodiment, as shown in FIG. 3, the coil part 40 has the 1st normal winding area | region 40a, the 2nd normal winding area | region 40b, and the low density winding area | region 40c. The first normal winding region 40 a is a region in which the four wires 41 to 44 are wound around the core portion 22 in close contact with each other. Further, the second normal winding region 40b is composed of four wires 41 to 44 constituting the first normal winding region 40a and continuous wires 41 to 44, which are in close contact with each other and the core portion 22. It is an area wound around.

  The low density winding region 40c is formed between the first normal winding region 40a and the second normal winding region 40b along the winding axis (X axis) of the winding core portion 22, and the wire 41 along the X axis. It is an area | region where the winding density of -44 is low. The low-density winding area 40c is composed of four wires 41 to 44 constituting the first normal winding area 40a and continuous wires 41 to 44, and the first normal winding area 40a and the second normal winding area 40a. The wire is wound at a winding density lower than the winding density of the wire in the normal winding region 40b.

  In the low density winding region 40c, as shown in FIG. 1, the surface of the winding core portion 22 is exposed. On the other hand, in the 1st normal winding area | region 40a and the 2nd normal winding area | region 40b, it is covered with the wires 41-44, and the surface of the core part 22 is not exposed outside.

  As shown in FIG. 3, the length α of the low-density winding region 40c in the winding axis (X-axis direction) direction corresponds to the maximum gap width in the winding axis direction at which the surface of the core portion 22 is exposed, and at least It is equal to or larger than the wire diameter of the wires 41 to 44. In the present embodiment, the wires 41 to 44 are all composed of wires having the same wire diameter, but may be different depending on circumstances. When wires having different wire diameters are used as the wires 41 to 44, the gap width (length α) is equal to or greater than the smallest wire diameter.

  Preferably, the length of the low-density winding region in the winding axis direction is α, the length (full length) of the coil portion 40 in the winding axis direction is L0, and the wire diameters of the wires 41 to 44 are d. When the number of wires 41 to 44 wound around each layer is n (n = 2 in this embodiment) and the minimum number of turns is T (an integer of 1 or more), the relationship of d × n × T ≦ α <L0 It is in. The total length L0 of the coil portion 40 is equal to or less than the total length of the core portion 22 in the Z-axis direction.

  Preferably, in the first normal winding region 40a and the second normal winding region 40b, the minimum length of the region having the shortest length in the winding axis direction is such that the four wires 41 to 44 are two or more layers. It is the length wound by 2 or more. That is, when the length of the first normal winding region 40a in the X-axis direction is X1, and the length of the second normal winding region 40b is X2, these lengths X1 and X2 are each four. It is the length which wound the wire 41-44 of the book in two or more layers and two or more turns. In this embodiment, the relationship is L0 = X1 + α + X2. Preferably, X1 / X2 is 0.5 to 2, more preferably in the vicinity of 1.

  Four wires 41 are formed at the boundary between the first normal winding region 40a and the low density region 40c, the boundary between the second normal winding region 40b and the low density region 40c, or at least one end of the coil portion 40 in the X-axis direction. The winding of .about.44 is released, and for example, at least one of the wires 41 and 43 located in the second layer may fall to the first layer. In the example shown in FIG. 3, the wire 43 positioned in the second layer falls to the first layer at the boundary between the first normal winding region 40 a and the low density region 40 c. Moreover, the wire 43 located in the second layer at the end of the coil portion 40 in the second normal winding region 40b falls to the first layer.

  In this embodiment, the 1st normal winding area | region 40a and the 2nd normal winding area | region 40b are comprised by the same continuous four wires 41-44, a pair of wires 42 and 44 of the 1st layer, and two layers A pair of eyes 41 and 43 are wound in opposite directions. Therefore, in the low-density winding region 40c, as shown in FIG. 1, at least one portion (preferably, a portion where the pair of wires 42 and 44 in the first layer intersects with the pair of wires 41 and 43 in the second layer) Is formed at one location.

  As shown in FIGS. 1, 2D, and 4, the wire ends 41a and 41b of the wire 41 are connected to the terminal portions 54 and 52, respectively, and the wire ends 42a and 42b of the wire 42 are connected to the terminal portions 51 and 54, respectively. The wire ends 43a and 43b of the wire 43 are connected to the terminal portions 55 and 53, respectively. Wire ends 44a and 44b of the wire 44 are connected to terminal portions 53 and 56, respectively.

  As shown in FIG. 4, the terminal portions 51 and 52 are used as a positive input terminal IN + and a negative input terminal IN− for balanced input, respectively. The terminal portions 55 and 56 are used as a positive output terminal OUT + and a negative output terminal OUT−, respectively, for balanced output. Terminal portions 53 and 54 are used as intermediate taps CT on the input side and output side, respectively. The wires 41 and 42 constitute the primary winding of the pulse transformer, and the wires 43 and 44 constitute the secondary winding of the pulse transformer.

  In the manufacture of the coil component 10, first, the drum-type first core 20 provided with the terminal portions 51 to 56 and the wires 41 to 44 are prepared. The first core 20 is formed and sintered from, for example, a magnetic material having a relatively high magnetic permeability, such as Ni—Zn ferrite, Mn—Zn ferrite, or metal magnetic material. It is produced by doing. The metal terminal portions 51 to 56 are fixed to the flange portion 24 of the first core 20 by adhesion or the like. In addition, the terminal parts 51-56 may be provided in the collar part 24 by forming a conductor film in the 1st core 20 by printing, plating, etc., and baking the conductor film.

  As the wires 41 to 44, for example, a core material made of a good conductor such as copper (Cu) is covered with an insulating material made of imide-modified polyurethane and the outermost surface is covered with a thin resin film such as polyester. Can do. The first core 20 and the wires 41 to 44 on which the prepared terminal portions 51 to 56 are installed are set in a winding machine, and the wires 41 to 44 are wound around the core portion 22 of the first core 20 in a predetermined order. Turned. The wire ends 41a to 44a and 41b to 44b of the wound wires 41 to 44 are fixed to predetermined terminal portions 51 to 56 shown in FIGS. 2D and 4 by silver brazing, thermocompression bonding, laser bonding, or the like. .

  Next, a plate-like second core 30 is prepared and joined to the first core 20 around which the coil portion 40 is wound. Similar to the first core 20, the second core 30 is composed of a sintered or molded body of a magnetic material composed of Ni—Zn-based ferrite, Mn—Zn-based ferrite, metal magnetic material, or the like. .

  In the pulse transformer 10 according to the present embodiment, it is possible to reduce the insertion loss at a high frequency with a particularly strict standard. Although the reason why the insertion loss can be reduced in the high frequency region is not necessarily clear, as shown in FIG. 3, there are four lines at the boundary between the low density winding region 40c and the first normal winding region 40a. The wire 41 to 44 is unwound, and the wire 43 located in the second layer falls to the first layer and is located next to the wire 42. It has been.

  In the pulse transformer 10 of the present embodiment, since the insertion loss in the high frequency region can be reduced, the amount of signal attenuation at the high frequency is reduced, and a high-speed data signal can be sent accurately over a long (long) distance.

Second Embodiment The coil component 10a as the pulse transformer of the second embodiment shown in FIG. 5 is different in that four terminal portions are provided on each of the flange portions 24 at both ends, for a total of eight terminal portions. The configuration of is the same as that of the coil component 10 of the first embodiment. The terminal portions 53a and 53b of the coil component 10a correspond to the terminal portion 53 of the coil component 10 of the first embodiment, and the terminal portions 54a and 54b of the coil component 10a correspond to the terminal portion 54 of the coil component 10. ing.

  In the coil component 10a, the electrical connection between the wire end 43b and the wire end 44a and the electrical connection between the wire end 41a and the wire end 42b are performed via a wiring pattern on the wiring board on which the coil component 10a is mounted. Done. Other configurations and operational effects of the coil component 10a according to the present embodiment are the same as in the case of the first embodiment, and a detailed description thereof will be omitted.

Third Embodiment In the present embodiment, although not shown, the coil portion 40 shown in FIGS. 1 and 5 further has a third normal winding region, and a third normal winding region along the winding axis direction. Between the 2nd normal winding area | region 40a, you may have further the low density winding area | region similar to the low density winding area | region 40c.

  The coil unit 40 further includes a fourth normal winding region, and between the fourth normal winding region and the first normal winding region or the fourth normal winding along the winding axis direction. A low density winding region similar to the low density winding region may be further provided between the region and the third normal winding region. Hereinafter, similarly, the fifth and subsequent normal winding regions may be formed through the low density winding region 40c. The third and subsequent normal winding regions have the same configuration as the first normal winding region 40a or the second normal winding region 40b. Other configurations and operational effects of the coil component 10a according to the present embodiment are the same as in the case of the first embodiment, and a detailed description thereof will be omitted.

  The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the present invention.

  For example, the shape of the first core 20 is not limited to the drum shape shown in the embodiment, and may be an arbitrary shape including a pair of core end portions at both ends of the core portion, such as a U shape. Further, the two flange portions 24 of the first core 20 may have the same shape or different shapes.

  In the above-described embodiment, the first layer of the coil unit 40 is configured by the two wires 42 and 44, and the second layer is configured by the other two wires 41 and 43. The wire 42 may be constituted by one wire continuous at the terminal portion 54. Further, the wire 43 and the wire 44 may be configured by a single wire continuous at the terminal portion 53.

  Furthermore, in the embodiment described above, the terminal portions 53 and 54 are used, but the terminal portions 53 and 54 may be omitted depending on the application. That is, as shown in FIG. 4, the terminal sections 53 and 54 used as the intermediate tap CT on the input side and the output side may be deleted to constitute a pulse transformer. In that case, a pulse transformer is formed using only two wires.

  Furthermore, in this invention, you may reduce the number of the wires used at the time of winding by devising the winding method of the wire with respect to the winding core part 22. FIG. For example, after forming the first layer of the coil unit 40 on the core 22 using one or two wires, the second layer of the coil unit 40 is formed using the same wire, and the primary winding of the coil unit And the secondary winding may be cut to separate the primary winding and the secondary winding.

  In the embodiment described above, as shown in FIG. 1, the first pair of wires 42 and 44 and the second pair of wires 41 and 43 intersect on the upper surface in the Z-axis direction of the core portion 22. However, the present invention is not limited to this. For example, the intersecting portion may be formed on the lower surface in the Z-axis direction of the core portion 22 or may be formed on the side surface of the core portion 22 facing the Y-axis direction.

  Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.

Example 1
As shown in FIGS. 1 to 3, the pulse has a relationship of L0 = X1 + α + X2, α is an interval equal to or more than two wire diameters of the wire, and X1 is composed of a coil component 10 substantially equal to X2. A transformer was produced. The result of measuring the insertion loss of the pulse transformer is shown by a curve ex1 in FIG. In FIG. 6, the horizontal axis represents the measurement frequency (exponential display and the unit is MHz), and the vertical axis represents the insertion loss (signal attenuation characteristic / unit is dB). The insertion loss was measured with a network analyzer.

Example 2
Next to the second normal winding region 40b in the coil portion 40 shown in FIG. 3, a third normal winding region (not shown but its length in the Z-axis direction is X3) is separated from another low-density region (not shown). The length of the Z-axis direction is formed through α), and a relationship of L0 = X1 + α + X2 + α + X3 is established, and a pulse transformer composed of coil components is formed in the same manner as in Example 1 except that X1, X2, and X3 are substantially equal. Produced. The result of measuring the insertion loss (Insertion Loss) of the pulse transformer in the same manner as in Example 1 is shown by a curve ex2 in FIG.

Example 3
Next to the third normal winding region, a fourth normal winding region (not shown but its length in the Z-axis direction is X4), another low-density region (not shown but its length in the Z-axis direction is α ), And a relationship of L0 = X1 + α + X2 + α + X3 + α + X4 was made in the same manner as in Example 2 except that X1, X2, X3, and X4 were substantially equal, and a pulse transformer made of a coil component was manufactured. The result of measuring the insertion loss (Insertion Loss) of the pulse transformer in the same manner as in Example 1 is shown by a curve ex3 in FIG.

Comparative Example 1
A coil part is formed in the same manner as in Example 1 except that the coil portion is formed by winding the wires 41 to 44 with the same number of turns as in Example 1 without forming the low density region 40c as shown in FIG. The following pulse transformer was produced. The result of measuring the insertion loss (Insertion Loss) of the pulse transformer in the same manner as in Example 1 is shown by a curve Ce1 in FIG.

Evaluation As shown in FIG. 6, in all the pulse transformers (ex1 to ex3) according to Examples 1 to 3, compared with the pulse transformer (Ce1) according to Comparative Example 1, in particular, in a high frequency band up to 250 MHz. It was confirmed that the insertion loss can be made to be less than the standard insertion loss St = −0.8 dB.

DESCRIPTION OF SYMBOLS 10 ... Coil component 20 ... 1st core 22 ... Core part 24 ... A collar part (core edge part)
30 ... Second core

Claims (9)

A pulse transformer having a winding core part and a coil part in which a wire is wound around the winding core part,
The coil portion is
A first normal winding region in which the wires are in close contact with each other and wound around the core portion;
A second continuous winding region formed of a wire continuous with the wire constituting the first normal winding region and wound around the core portion in close contact with each other;
A low-density winding region formed between the first normal winding region and the second normal winding region along the winding axis of the winding core portion and having a low winding density of the wire along the winding shaft and, the possess,
In the first normal winding region and the second normal winding region, the wire is bifilar wound in two or more layers on the core portion,
In the low-density winding region, at least one portion where the pair of wires wound in the first layer and the pair of wires wound in the second layer intersect is formed in at least one place. Pulse transformer.   The pulse transformer according to claim 1, wherein a surface of the core portion is exposed in the low density winding region.   The pulse transformer according to claim 2, wherein a gap width in the winding axis direction in which a surface of the winding core part is exposed is equal to or larger than a wire diameter of the wire.   The pulse transformer according to any one of claims 1 to 3, wherein a length of the low-density winding region in the winding axis direction is twice or more a wire diameter of the wire.   5. The wire according to claim 1, wherein a part of the plurality of wires constitutes a first layer of the coil part, and another part of the wires constitute a second layer of the coil part. The described pulse transformer.   The pulse transformer according to claim 5, wherein the wire in the first layer and the wire in the second layer are wound in opposite directions. According to the respective lengths of the winding axis direction of the first normal load area and the second normal winding area, any one of claims 1 to 6 wherein the wire is a length wound on two or more volumes Pulse transformer.   The coil portion is formed of a wire continuous with the wire constituting the second normal winding region, and further includes a third normal winding region wound around the core portion in close contact with each other. A low-density winding region similar to the low-density winding region is formed between the third normal winding region and the second normal winding region along the winding axis direction. Item 8. The pulse transformer according to any one of Items 1 to 7.   The pulse transformer according to claim 8, wherein a length of the third normal winding region in the winding axis direction is a length in which the wire is wound twice or more.

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