JP2008091359A - Wire wound common mode choke coil - Google Patents

Abstract

An object of the present invention is to provide a non-directional winding type common mode choke coil in which a common mode impedance is increased and a predetermined characteristic impedance can be easily obtained.
A winding type in which a pair of wires are wound around a winding portion 1a of a magnetic or non-magnetic drum core 1 and a winding terminal is electrically connected to an electrode 3 provided on a flange portion 1b of the drum core 1. The common mode choke coil is characterized in that it is wound symmetrically from the center position of the winding portion 1a to the flanges 1b and 1b at both ends with a distance (a) between the wires and a winding interval (b). To do.
[Selection] Figure 1

Description

  The present invention relates to a wire wound common mode choke coil used for a high-speed serial interface that supports high definition video and a transmission rate in the GHz band.

  Conventionally, as this type of wire wound common mode choke coil, as shown in FIG. 5 (a), a structure in which a pair of wires are in close contact with a winding portion of a magnetic or nonmagnetic drum core and is bifilar wound is common. . Moreover, what wound by the pair wire which coat | covered a pair of parallel wire material with the insulating material integrally, or provided the fixed winding space | interval is disclosed (refer patent document 1). Further, a pair of wire rods having a constant interval (distance between wire rods) and a pair of windings with a winding interval are disclosed (see Patent Document 2).

Such a common mode choke coil is used in a next-generation video / audio signal input / output interface developed for digital home appliances and AV devices, and its specification is determined by the method.
For example, as a specification of a physical layer of HDMI (High Definition Multimedia Interface), a T.V. M.M. D. S (Transition Minimized Differential Signaling) is used. The HDMI transmission rate is 1.65 Gbps at maximum, and a high-speed pulse signal with a maximum pulse rise time of Tr (10−90) = 200 ps is used.

  In addition, the serial ATA specification that replaces the conventional parallel ATA standard connected to a personal computer (PC) and a hard disk drive (HDD) has software compatibility, and the transmission speed is 1.5 Gbps and 3.0 Gbps. The pulse rise time uses a high-speed pulse signal of Tr (20-80) = 100 ps.

In order to transmit high-speed signals accurately without distortion or delay, it is required to keep the characteristic impedance of the transmission line constant and to match the connected devices. In recent high-speed interfaces, this characteristic impedance is required. Therefore, there is a need for a common mode choke coil that satisfies this standard.
In the conventional bifilar-wound common mode choke coil, it is difficult to aim at 100Ω, which is the center value of the standard of the characteristic impedance that is defined.
JP 2004-146683 A JP 2004-146671 A

In particular, in order to bring the characteristic impedance of the common mode choke coil close to 100Ω, it is necessary to reduce the number of turns of the winding and to reduce the line capacitance of the winding. However, if the number of turns is reduced, the common mode impedance is reduced, and the ability to remove common mode noise is reduced. Also, if the number of turns is increased in order to increase the common mode impedance and increase the noise reduction capability, the characteristic impedance deviates from 100Ω.
In addition, in order to transmit an accurate signal, matching is performed between connected devices. Therefore, in these common mode choke coils, there are characteristics seen from the winding start side and winding end side. It is required that they are equivalent, that is, the characteristics seen from the input side and the characteristics seen from the output side are the same.

  The present invention has been made in view of the above problems, and it is an object of the present invention to provide a winding-type common mode choke coil that has a high common mode impedance and can easily obtain a predetermined characteristic impedance.

  In order to solve the above-mentioned problems, a wound common mode choke coil according to the invention of claim 1 is formed by winding a pair of wires around a winding part of a magnetic or nonmagnetic drum core and providing an electrode provided on a flange part of the drum core. In a wound common mode choke coil in which winding ends are electrically connected, a distance (a) between wires and a winding interval (b) are provided and symmetrical from the center position of the winding portion to the flange portions at both ends. It is characterized by being wound.

  The wound common mode choke coil according to the invention of claim 2 is configured such that a pair of wires are wound around a winding portion of a magnetic or non-magnetic drum core, and a winding terminal is electrically connected to an electrode provided on a flange portion of the drum core. In the wound common mode choke coil, a groove for fixing a pair of wires is provided at the center position of the winding portion of the drum core, and a distance (a) between wires and a winding interval (b) are provided. It is characterized by being symmetrically wound from the groove to the flanges at both ends.

  According to a third aspect and a fourth aspect of the present invention, in the wound common mode choke coil according to the second aspect, the groove of the drum core is provided at a central position of the winding portion at an outer periphery or a part of the outer periphery. It is characterized in that it is provided on two side faces opposite to the center position of.

According to claims 5 to 8, in the wound common mode choke coil according to claims 1 to 4,
The wire-to-wire distance (a) and the winding interval (b) are fixed intervals,
The wire-to-wire distance (a) and the winding interval (b) are sequentially expanded from the center position of the winding portion or the groove to the flange portion,
The wire-to-wire distance (a) is constant, and the winding interval (b) is sequentially expanded from the center position of the winding part or from the groove to the flange part,
The winding interval (b) is constant, and the distance (a) between the wires is gradually increased from the center position of the winding portion or from the groove to the flange portion, and symmetrical from the center position of the winding portion or from the groove to the flange portion. It is characterized by being wound around.

  According to a ninth aspect of the present invention, in the wound common mode choke coil according to the first to eighth aspects, a magnetic or nonmagnetic plate-like core is provided on the upper surface of the flange portion of the drum core.

  As described above, according to the wound common mode choke coil of the present invention, a predetermined distance (a) between the pair of wires from the center position of the winding portion of the drum core to the flanges at both ends and a predetermined winding By winding symmetrically with the interval (b), the common mode impedance can be increased, a predetermined characteristic impedance can be easily obtained, and a predetermined characteristic impedance having no directivity can be obtained.

  Hereinafter, the best mode of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view of a wire wound common mode choke coil according to an embodiment of the present invention. FIG. 2 is a perspective view of a drum core used in the wire wound common mode choke coil according to the embodiment of the present invention. FIG. 3 is a bottom view for explaining the winding portion. Here, FIG. 1 and FIG. 2 show the state in which the electrode on the mounting surface is the top surface. As an example, since the target center value of characteristic impedance is set to 100Ω, the number of turns will be described with respect to 3 turns.

  1 and 2, reference numeral 1 denotes a rectangular columnar drum core made of a magnetic material (ferrite, etc.) or a non-magnetic material (ceramics, etc.), and has a rectangular columnar flange 1b at both ends of the winding portion 1a. . Four electrodes 3 are formed on the two flanges 1b by baking metal paste, metal plating or the like. The electrodes 3 are respectively formed on the outer peripheral surface of the flange portion 1b along the bottom side (the mounting surface; however, the top surface in FIG. 1) and partly upward from the bottom surface side. Reference numeral 2 denotes a pair of winding wires L1 and L2 made of two insulating film conductors, and 4 denotes a thin rectangular plate-like core made of a magnetic material (such as ferrite) or a non-magnetic material (such as ceramic).

  The winding part 1a of the drum core 1 is provided with a groove 1c at the center position of the winding part. The groove 1c is a guide for positioning the pair of winding wires L1 and L2 in close contact with each other at the center position of the winding portion, and the dimension thereof is the same width x as the pair of winding wires. It may be a depth at which the winding wire can be positioned. For example, the depth may be about half the outer diameter of the winding wire. If the center position can be easily set by a winding machine or the like and a mechanism for fixing the winding is provided, the groove may not be used.

As shown in FIG. 3, the winding portion 1a of the drum core 1 has a number of turns and a distance between the wire rods so that the winding state is symmetrical from the groove x of the drum core toward the flanges at both ends. (A) A coil 2 wound with a winding interval (b) is formed.
It is desirable to set the inter-wire distance (a) and the winding interval (b) in accordance with required characteristics. In particular, in the conventional characteristics, when the number of turns tends to be insufficient, the number of turns can be increased by providing the distance (a) between the wires and the winding interval (b) as described above.
Further, the winding wire ends of the winding wires L1 and L2 of the coil 2 are electrically connected to the four electrodes 3 provided on the two specified flanges 1b by thermocompression bonding or the like.

  Returning to FIG. 1, after a pair of winding wires are wound on the drum core 1, the plate-like core 4 is fixed to the gaps 1 b, 1 b opposite to the electrode surface of the drum core 1 with an adhesive or the like. The The plate-like core 4 is provided so that the common mode choke coil (product) has a flat upper surface so that it can be sucked by the suction nozzle of the automatic mounting machine. If both are made of a magnetic material, they can be used in accordance with characteristics such as reducing leakage magnetic flux and improving common mode noise suppression characteristics. Furthermore, by changing the relative permeability of the plate-like core made of a magnetic material to the relative permeability of the drum core, it contributes to improving the degree of freedom in designing the common mode impedance.

  As the winding method, as shown in FIG. 3, the distance between the two wire rods L1 and L2 is set so as to be symmetrical from the center (w2) of the drum core toward the flanges at both ends. a) and the number of turns specified by providing a winding interval (b), in the figure, one turn (w3) in one heel side direction and one turn (w1) in the other heel side direction is symmetrical. A line is made.

That is, a winding wire having a predetermined number of turns is taken out, and the central winding wire is aligned with the groove 1c in the center of the drum core (w2), and the wire is set from the groove toward one side. The specified number of turns (w3 or W1) is wound with an interval (a) and a winding interval (b). Then, the specified number of turns (w1 or W3) is wound from the groove 1c toward the other flange with the wire-to-wire distance (a) and the winding interval (b) set on the other side. .
As described above, the winding 2 is symmetrical between the center position of the drum core 1 and the flanges at both ends, and the pair of winding wires L1 and L2 are set to the distance (a) between the wires and the winding interval (b). It is characteristic that it is provided and wound. However, the number of turns, the distance between wire rods (a), and the winding interval (b) may be set in accordance with target characteristics.

Next, it is good also as a groove shape as shown in FIG. 4 about the groove | channel of the drum core which is another Example of this invention.
FIG. 4A shows a groove provided only on the bottom surface of the drum core.
FIG. 4B shows the drum core provided with grooves on both side surfaces.
In FIG. 4C, a groove is provided on the entire circumference of the drum core. However, since the core diameter of the drum core is reduced, it is necessary to consider strength and the like. Thus, it is desirable to determine the groove position, groove width, and the like in accordance with the desired characteristics. In the figure, the grooves are provided obliquely so as to pass through the center position of the drum core in order to facilitate winding, but may be provided at right angles to the winding axis.

Next, the results of studies on the characteristics of the conventional product and the product of the present invention will be described below.
The samples examined for comparison are as follows.
As shown in FIG. 5A, sample No. 1 is a two-turn product in a conventional example in which a pair of closely wound winding wires are wound by bifilar with a winding interval.
As shown in FIG. 5B, sample No. 2 is a three-turn product in a conventional example in which a pair of closely wound winding wires are wound by bifilar with a winding interval.
Sample No. 3 is the product of the present invention shown in FIG. 3 described in the above embodiment.
Sample No. 4 is obtained by winding a pair of winding wires asymmetrically. As shown in FIG. 5C, the winding interval is the same from the center and the distances (a1, a2) between the wires are made different. 3 turn product.
Sample No. 5 is obtained by winding a pair of winding wires asymmetrically. As shown in FIG. 5D, the distance between the wires from the center is the same, and the winding intervals (b1, b2) are different. 3 turn product.

  For the sample No., the normal mode and common mode impedance and characteristic impedance were compared. The characteristics and dimensions of the drum core and plate core used in the sample are the same, and the winding wire used has the same wire diameter as the product of the present invention.

FIG. 6 compares the difference in the number of turns using Sample No. 1-3.
As shown in FIG.
(1) Impedance (Ω) at a frequency of 1 GHz in normal mode and common mode.
(2) Peak frequency (GHz) at which impedance (Ω) peaks in normal mode and common mode.
(3) As characteristic impedance, the maximum value Max (Ω) and the minimum value Min (Ω) of the impedance at Tr (10−90) = 200 ps were measured.

As a result, as shown in FIG. 6, the two-turn product of sample No. 1 has a lower peak frequency of normal mode and common mode impedance at 1 GHz than the three-turn product of sample No. 2 and sample No. 3.
In addition, the characteristic impedance is substantially equal to the target value of the sample No. 2 turn product and the sample No. 3 sample product for the target value of 100Ω at Tr (10−90) = 200 ps. Two-turn products are a little low.
The 3-turn product of sample No. 2 showed a low result with respect to the target value of 100Ω.
Therefore, in the conventional winding method, the 2-turn product has a shortage in characteristic impedance, and the 3-turn product has a characteristic impedance that tends to be short of the target.

FIG. 7 compares the characteristic impedance of the measurement position with respect to the forward direction and the reverse direction with respect to the symmetry of the winding position using Sample No. 3-5.
As can be seen from the results of FIG. 6, the characteristic impedance was measured by changing the input / output positions of the three-turn product having the same characteristic impedance. For example, the measurement from one side is the forward direction, and the measurement from the other side is the reverse direction.

As a result, as shown in FIG. 7, the characteristic impedance in the forward direction or the reverse direction tends to deviate from the target value when the distance (a) between the wires or the winding interval (b) is not symmetric as in Sample Nos. 4 and 5.
Thus, from the results of FIGS. 6 and 7, in the example of the present invention (sample No. 3), the impedance in the normal mode and the common mode is high (compared to the two-turn product), and the target value is 100Ω, which is the target value Therefore, high-speed signals can be transmitted accurately without distortion or delay, and the characteristic impedance of the transmission line can be kept constant. Can be planned.

For reference, FIG. 8 shows the frequency characteristics of impedance in Sample No. 3 which is an embodiment of the present invention, and FIG. 9 shows the characteristic impedance.
FIG. 8 shows frequency characteristics of frequency on the horizontal axis and frequency characteristics of impedance on the vertical axis.
FIG. 9 is a waveform of Tr (10−90) = 200 ps at the pulse rise time of the characteristic impedance, the horizontal axis is ps, the vertical axis is impedance (Ω), the center line MI = 100Ω, and the vertical symmetry line of MI is ± 15Ω is shown.

  As described above, the wound common mode choke coil of the present invention can easily design the normal mode and common mode impedances and characteristic impedances between signal lines to desired values. As a result, the characteristic impedance can be easily matched with the external circuit, and the effect of improving the quality of the signal waveform can be obtained.

The perspective view which turned up the bottom which is an example of the winding type common mode choke coil concerning the present invention The perspective view of the drum core used for the winding type common mode choke coil which concerns on this invention The bottom view which shows the winding state which is an Example of the winding type common mode choke coil based on this invention Bottom views (a), (b), (c) which are other embodiments of the drum core used in the wire wound common mode choke coil according to the present invention. Bottom views (a), (b), (c), (d) showing windings of the common mode choke coil used for the characteristic comparison Characteristic data with different number of turns Characteristic data comparing winding symmetry Frequency characteristics of impedance of sample No. 3 which is an embodiment of the present invention Characteristic impedance waveform of sample No. 3 which is an embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Drum core 1a Winding part 1b 鍔 1c Groove 2 Winding 3 Electrode 4 Plate-shaped core L1, L2 Winding wire material a Winding wire material distance b Winding space | interval

Claims (9)

In a winding type common mode choke coil in which a pair of wires are wound around a winding part of a magnetic or nonmagnetic drum core, and a winding terminal is electrically connected to an electrode provided on a flange part of the drum core,
A wire wound common mode choke coil characterized in that it is provided with a distance (a) between wires and a winding interval (b) and is symmetrically wound from the center position of the winding portion to the flanges at both ends. In a winding type common mode choke coil in which a pair of wires are wound around a winding part of a magnetic or nonmagnetic drum core, and a winding terminal is electrically connected to an electrode provided on a flange part of the drum core,
A groove for fixing a pair of wire rods is provided at the center position of the winding portion of the drum core, and a distance between the wire rods (a) and a winding interval (b) are provided to symmetrically wind from the groove to the flanges at both ends. A wound-type common mode choke coil characterized by comprising: 3. The wound common mode choke coil according to claim 2, wherein a groove of the drum core is provided at a central position of the winding portion on an outer periphery or a part of the outer periphery. The wound-type common mode choke coil according to claim 2, wherein the groove of the drum core is provided on two side faces opposed to the center position of the winding portion. The wire-to-wire distance (a) and the winding interval (b) are set at a constant interval, and are wound symmetrically from the center position of the winding portion or from the groove to the flange portion. Item 5. A wire wound common mode choke coil according to item 4. The wire-to-wire distance (a) and the winding interval (b) are sequentially expanded from the center position of the winding portion or from the groove to the flange portion, and wound symmetrically. 4. A wire wound common mode choke coil according to item 4. 2. The wire-to-wire distance (a) is constant, and the winding interval (b) is gradually expanded from the center position of the winding portion or from the groove to the flange portion, and is wound symmetrically. 5. A wire wound common mode choke coil according to claim 4. The winding interval (b) is constant, and the distance (a) between the wires is gradually expanded from the center position of the winding portion or from the groove to the flange portion, and is wound symmetrically. 5. A wire wound common mode choke coil according to claim 4. 9. A wound common mode choke coil according to claim 1, wherein a magnetic or non-magnetic plate-like core is provided on the upper surface of the flange portion of the drum core.

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