JPH02241010A - Fixed inductor - Google Patents

Abstract

PURPOSE:To reduce the stray capacitance of an inductor, and obtain a high frequency inductor capable of finely adjusting the inductance value by winding one or several turns of the winding end wire of a coil, around a protruding part on the outside plane of a flange of a drum type core, and connecting the wire with a metal plate terminal. CONSTITUTION:A pair of metal terminals 14 is fixed on the outside plane part of one flange of a drum type magnetic core 11; a protruding part 13 is installed at the nearly central part of the outside plane part of the other flange; the starting wire 17 of a coil wound around the drum type magnetic core 11 by a specified number of turns is directly connected with one side metal plate terminal 14; the ending wire 18 of the coil is wound around the protruding part of the outside plane part of the flange of the above drum type magnetic core 11 by one or more turns, and connected with the other side metal plate terminal 14. By this constitution, stray capacitance generating between the starting wire 17 and the ending wire 18 can be reduced: the ending wire 18 can be led out from an arbitrary position on the circumference of the drum type magnetic core 11, so that fine adjustment such as 1/2 turn, 1/4 turn, etc., is enabled; further by adjusting the number of turns around the protruding part 13, the inductance value can be finely adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a fixed inductor used in various electronic devices 9 and communication devices.

Conventional technology In recent years, with the rapid progress of semiconductor technology, various electronic devices1
The digitalization and high frequency of communication equipment are progressing, and improvements in functionality and performance are being attempted, and high-density surface mounting methods using chip components are becoming widespread, greatly contributing to the miniaturization and thinning of equipment. Among them, fixed inductors used in devices that require high-speed processing of digital signals and high-frequency signal processing, such as satellite broadcasting and TV receivers, have improved high-frequency performance of the sea layer compared to conventional ones. and high characteristic accuracy is required. -Inductors with small inductance values are mainly used in high-frequency circuits for boat fishing, but inductance values as small as a few nano to several tens of nanohenries, as well as reducing the stray capacitance of the inductor,
That is, it is necessary that the self-resonant frequency of the inductor itself is sufficiently higher than the operating frequency.

A conventional fixed inductor will be explained below with reference to the drawings.

4 and 5 both show examples of conventional fixed inductors, and FIG. 4 shows a transparent perspective view of a chip type fixed inductor. In the figure, 1 is a drum-shaped magnetic core, 2 is a coil wound around the drum-shaped magnetic core 1, 4 is a terminal made of a metal plate, and 5 is a winding start line 7 of the coil 2. The protruding portion 6 that connects the winding end wire 8 and the metal plate terminal 4 is an exterior molded body. In a chip-type fixed inductor with such a configuration, the drum-shaped magnetic core 1 is fixed in advance to the 4 surfaces of a pair of metal plate terminals with an adhesive, etc., and the wire is first wired at the beginning of the second winding of the coil using an automatic winding and wiring machine. 7 is wound and fixed around the protruding part 6 of one metal plate terminal 4, the coil 2 is wound, and the winding end wire 8 is wound and fixed around the protruding part 6 of the other terminal 4, and then both protrusions are fixed. It is manufactured by a manufacturing method in which the parts 6 are connected by soldering or the like, and the entire body is covered with an exterior molded body 6.

Similarly, FIG. 6 shows a perspective view of the leaded fixed inductor. In the figure, 1.2 and 7.8 are the same as above, and their explanation will be omitted. Reference numeral 9 designates a pair of lead terminals embedded in the outer surface of one of the ribs of the drum-shaped magnetic core 1. In the lead-type fixed inductor having such a configuration, the winding start line 7 of the coil 2 is connected near the embedded fixed part of the lead terminal 9 to the drum-shaped magnetic core 1.
After fixing the winding of the wire 8 at the end of the first winding to the lead terminal 9,
Connected by soldering.

When using such a fixed inductor in a high frequency circuit, a drum-shaped magnetic core 1 is used to achieve a small inductance value.
This was accomplished by using a ferrite material with low magnetic permeability, or by using a ceramic material such as alumina, and by extremely reducing the number of turns.

Problems to be Solved by the Invention It is generally known that inductors have stray capacitance between the wires of the windings. Figure 6a shows this situation.
What is the circuit shown in ? From this, the capacitance between adjacent copper wires is 01...On-+ (n is the winding) in the figure, but they are connected in series, and as a whole, between the terminals of the inductor. The effect on the equivalent stray capacitance that appears is not very large.

In addition to the above-mentioned stray capacitance, there is also a stray capacitance (Co in the figure) that occurs directly between the winding start wire and the winding end wire of the coil, and this directly affects the stray capacitance value between the inductor terminals. Here, the circuit when the inductor is viewed from the terminals is expressed as shown in Figure 6, and the stray capacitance C is the sum of the inter-winding capacitance and the line-to-line capacitance at the beginning and end of the winding. . Further, R in the figure is the sum of the resistance of the coiled copper wire and the loss of the drum-shaped magnetic core. As is clear from these circuits, the inductor itself has an inductance component and a capacitance component, has a self-resonance phenomenon, and does not have its original function at frequencies near and above the self-resonance frequency. In order to make an inductor with good characteristics in a high frequency band, it is necessary to reduce stray capacitance, but in the inductor structure shown in the conventional example, the wire at the beginning and end of the first winding is wired on the single boxwood side of the drum-shaped magnetic core. Therefore, these two lines tend to approach each other and may even intersect, making it unsuitable for use at high frequencies where there is a large amount of stray capacitance.

In addition, in the configuration shown in the conventional example, the number of turns is adjusted in increments of one turn, which is a minute adjustment, for example, a % turn.

Z-turn adjustment is not possible. This can be achieved by using a small number of turns to obtain a small inductance value, but if the number of turns is adjusted by at least one turn, the change in inductance due to an increase or decrease of one turn is large, making it difficult to obtain the desired inductance value.

Therefore, it is necessary to use several types of drum-shaped magnetic cores with different core diameters or winding widths in order to obtain the desired inductance value with a specified number of turns, which increases management of materials and manufacturing. ing.

In view of the above-mentioned problems, the present invention provides a fixed inductor that is effective for high frequencies, which reduces the stray capacitance of the inductor, and also allows minute adjustment of the inductance value.

Means for Solving the Problem In order to solve this problem, the fixed inductor of the present invention has the following features:
A pair of metal plate terminals were fixed to the outer flat part of one rib of the drum-shaped magnetic core, a protrusion was provided approximately in the center of the outer flat part of the other rib, and the drum-shaped magnetic core was wound a predetermined number of times. The winding start wire of the coil is directly connected to one metal plate terminal, and the winding end wire of the coil is wound once or several times around the protrusion on the outer plane of the brim of the drum-shaped magnetic core, and then connected to the other metal plate terminal. It is configured by connecting to a terminal.

Operation With this configuration, the winding start line 9 of the coil is connected from both ends of the coil.
Since the winding end wire can be led out and wired separately, it is possible to reduce the stray capacitance between the winding start wire and the ninth winding end wire of the coil. An example of experimental data shows that the equivalent stray capacitance of an inductor is conventionally 0.
．． 7 pF can be reduced to 0.4 pF.

In addition, by changing the number of windings around the protrusion on the outer plane of the drum-shaped magnetic core's flange, and by leading the winding end line of the coil to an arbitrary point on the circumference of the drum-shaped magnetic core. , fine adjustment can be made with a small inductance value, and the desired inductance value can be easily obtained.

EXAMPLE A first example of the present invention will be described below with reference to the drawings. FIG. 1 is a transparent perspective view showing the internal structure of a fixed inductor in a first embodiment of the present invention. In FIG. 1, 11 is a drum-shaped magnetic core, 12 is a coil wound around this drum-shaped magnetic core 11, 13 is a protrusion provided at the center of the outer plane of the brim of the drum-shaped magnetic core 11, and 14 is a protrusion provided at the center. A pair of terminals made of a metal plate; 16 is a protrusion provided on the terminal 14 to connect the coil 12 and the terminal 14;
After winding and fixing the winding start wire 1A of the coil 12 and the winding end wire 18 of the coil 12, they are connected by soldering, etc. 16 is an exterior molded body made of heat-resistant resin such as epoxy resin;
It protects the internal structure of the coil and forms the overall outer shape of the coil. Next, an example of a method for manufacturing the fixed inductor shown in this embodiment will be described.

A pair of terminals 14 made of metal plates are fixed in advance with an adhesive to the outer surface of the collar of the drum-shaped magnetic core 11 on the side opposite to the collar having the protrusion 13. Next, the winding start wire 17 is wound and fixed around the terminal protrusion 16 on one side, and then the coil 12 is formed by winding the wire a predetermined number of times. After winding several turns, connect the other terminal 1
After winding and fixing the winding end wire 18 around the protrusion 16 of 4, and connecting the terminal 14 and the coil 12 by soldering at both terminal connection protrusions 16, the entire coil is attached to the exterior molded body 16.
Seal and mold.

In the fixed inductor manufactured and configured as described above, the winding start line 17 and the winding end line 18 can be led out apart from both ends of the drum-shaped core 110 winding groove, and the winding start line 17 and the winding end line 18 In addition, the winding end line 1B can be drawn out at any position on the circumference of the drum-shaped magnetic core 11, allowing fine adjustment of % turns and % turns. In addition, the inductance value can be finely adjusted by adjusting the number of times the drum-shaped magnetic core 11 is wound around the outer protruding portion 13 of the collar, and the inductance value can be easily adjusted to a desired value.

Next, an embodiment of WJ2 will be described with reference to the drawings.

FIG. 2 is a transparent perspective view showing the internal structure of the second embodiment. 11 to 18 in the figure are the same as those in FIG. 1, and their explanation will be omitted. Reference numeral 19 denotes a groove provided on the outer peripheral surface of the collar on which the protruding portion 13 of the drum-shaped magnetic core 11 is provided, and the groove is formed in a direction parallel to the central axis of the drum-shaped magnetic core 11.

The wire 1B at the end of the winding is led out from the coil 12 along the cut groove 19, wrapped around the outer protrusion 13 of the collar, and then wrapped again around the terminal protrusion 16 along the cut groove 19 to complete the wiring. conduct.

In this case, the two-turn winding line 18 passes through the kerf 19, but this may be the same kerf 19 or different kerfs.

The fixed inductor configured in this manner can reduce variations in the inductance value because the position at which the winding end wire 18 is led out from the drum-shaped magnetic core 11 can be fixed. The reduction of stray capacitance and the adjustment of minute inductance have the same effects as in the first embodiment.Note that the grooves 19 of this drum-shaped magnetic core 11 are provided only on the collar that has the outer surface protrusion 13 of the collar. ,
Needless to say, the same effect can be obtained even if it is provided on the circumferential surfaces of both ribs.

Next, a third embodiment will be described with reference to the drawings.

FIG. 3 is a sectional view showing a third embodiment. 11~ in the diagram
12 and 14 to 18 are the same as in FIG. 1, and their explanation will be omitted. 2o is a lead terminal buried in the center of the outer surface of the brim of the drum-shaped magnetic core 11, and 21 is the lead terminal 20
Indicates the adhesive used to secure the .

The fixed inductor configured in this manner allows reduction of inductor stray capacitance and minute inductance adjustment as in the first embodiment. In addition, the embedding and fixing of the lead terminal 2o can be performed simultaneously with the fixing of the drum-shaped magnetic core 11 and the terminal 14, resulting in high productivity.

In the first to third embodiments, the leadless chip-type fixed inductor having metal plate terminals has been described above, but instead of the pair of metal plate terminals 14, a pair of lead terminals are installed on the outer surface of the drum-shaped magnetic core brim. Even in the case of a lead-type fixed inductor embedded in the inductor, the same structure is possible and the same effect can be obtained.

Effects of the Invention As described above, the present invention has a pair of metal plate terminals fixed to the outer flat part of one of the ribs of a drum-shaped magnetic core, a protruding part provided approximately in the center of the outer flat part of the other rib, and The winding start wire of the coil wound a predetermined number of times around the drum-shaped magnetic core is directly connected to one metal plate terminal, and the winding end wire of the coil is connected to the protruding part on the outer plane of the brim of the drum-shaped magnetic core. ~ By winding the coil several times and connecting it to the other metal plate terminal to form a fixed inductor, the coil's winding start wire and the coil's winding end wire can be wired apart and connected to the terminal. It becomes possible to reduce the stray capacitance of In addition, the end wire of the coil can be led out from any position on the drum-shaped magnetic core, and the inductance value can be easily adjusted by setting the number of windings around the protrusion, making it suitable for use in high-frequency circuits. , it is possible to realize a fixed inductor with high productivity, and its practical effects are significant.

[Brief explanation of drawings]

FIG. 1 is a transparent perspective view showing the internal structure of a fixed inductor in a first embodiment of the present invention, FIG. 2 is a transparent perspective view showing the internal structure of a fixed inductor in a second embodiment of the present invention, and FIG. The figures are a sectional view showing the internal structure of a fixed inductor according to a third embodiment of the present invention, FIG. 4 is a transparent perspective view showing the internal structure of a conventional chip-type fixed inductor, and FIG.
The figure is a perspective view showing the structure of a conventional lead type fixed inductor, and FIGS. 6a and 6b show circuits of the fixed inductor. 11...Drum-shaped magnetic core, 12...Coil, 13...Protrusion, 14...Terminal,
16...Terminal connection protrusion, 16...
Exterior molded body, 17... Winding start line, 18...
... Winding end line, 19 ... Cut groove, 20 ...
・Lead terminal, 21...Adhesive. Name of agent: Patent attorney Shigetaka Awano and one other person

Claims (3)

[Claims] (1) A pair of metal plate terminals are fixed to the outer flat part of one rib of the drum-shaped magnetic core, a protrusion is provided approximately in the center of the outer flat part of the other rib, and the drum-shaped magnetic core is attached a predetermined number of times. The winding start wire of the wound coil is directly connected to one metal plate terminal, and the winding end wire of the coil is wound one to several times around the protrusion on the outer plane of the brim of the drum-shaped magnetic core and connected to the other metal plate terminal. Fixed inductor connected to plate terminal. (2) A protrusion is provided on the outer flat surface of one of the ribs of the drum-shaped magnetic core, and a plurality of protrusions are provided on the circumferential surface of the rib, or on the circumferential surface of both ribs in a direction parallel to the central axis of the drum-shaped magnetic core. 2. The fixed inductor according to claim 1, further comprising a kerf. (3) The fixed inductor according to claim 1, wherein a lead terminal is embedded as a protrusion provided on the outer flat surface of one of the ribs of the drum-shaped magnetic core.