JPH0410677Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] This invention relates to a chip-shaped LC filter that includes an inductor and a capacitor. [Prior Art] Chip-type LC filters of this type have been provided for a long time due to requirements such as ease of mounting on a circuit board. This chip-type LC filter is, for example, as shown in FIG. It has an equivalent circuit as shown in Figure 9. The structure of this chip-shaped LC filter will be explained with reference to FIGS. 7 and 8. A substantially U-shaped groove 3 is formed on one main surface of a rectangular ferrite plate 2, and a U-shaped groove 3 is formed in this groove. A conductive path 4 made of a metal plate is buried therein. A groove 5 is formed between the conductive paths 4, and one end of a lead portion 6 made of a metal plate is buried in this groove. is installed. Another ferrite plate 8 is adhered to the main surface of this ferrite plate 2 to form a ferrite block 1. Then, both ends of the conductive path 4 drawn out from between the ferrite plates 2 and 8 and the tip of the lead part 6 are bent along the ferrite plate 2 or 8, attached to the outer surface of the ferrite block 1, and Output terminals 9, 9 and a ground terminal 10 are formed on the surface. [Problems that the invention attempts to solve] However, this conventional chip-type LC filter has
It has the following problems. (1) Fine grooves 3 and 5 must be formed in the ferrite plate 2, which is a sintered body, and a metal plate that will become the conductive path 4 must be buried in these, which requires molding and assembly of the component parts. accompanied by difficulties. (2) Ferrite plates 2 and 8 are difficult to bond together, and mechanical and thermal shock may cause ferrite block 1 to bond to two ferrite plates 2 and 8.
It separates or peels easily. (3) Since the relatively fragile ferrite block 1 is exposed to the outside, the block 1 is easily chipped, especially at corners. (4) As the chip becomes smaller, the inductance rapidly decreases, so a small LC filter, in particular, cannot achieve a large attenuation rate in a high frequency band. This idea was made to solve the above-mentioned problems with conventional chip-type LC filters.
Although it has the same function and shape as the conventional LC filter mentioned above, the component parts are easy to manufacture and assemble, and the ferrite, which is the main component, is difficult to damage.
Moreover, it is an object of the present invention to provide a chip-type LC filter that can obtain relatively high inductance even with a small chip. [Means for Solving the Problem] The configuration of this invention will be described with reference to the reference numerals in FIGS. 1 to 6. Both sides of the linear conductive path 11 bent in a U shape are The conductive path 11 is bent into a meandering shape. Straight portions 11a, 11 on the outside of this conductive path 11
The ferrite beads 12, 12 are penetrated through the ferrite beads 12, 12, and the inner straight portions 11b, 11b are arranged close to the circumferential surfaces of the ferrite beads 12, 12 and substantially parallel to their central axes, and the same straight portions 11
One lead wire 19 of the capacitor 13 is connected to the conductive path 11 between the capacitors b and 11b. Ferrite beads 12, 12 and a capacitor 13 disposed between them are embedded in an insulating block 15 integrally molded into a chip shape. Both ends of the conductive path 11 drawn out from the insulating block 15 and the tip side of the other lead wire 14 of the capacitor 13 are formed flat, and both ends of the conductive path 11 and the flat portion of the lead wire 14 are connected to the insulating block 15.
The output terminal 16 is attached to one side of the
16 and a ground terminal 17 are formed. [Function] In this invention, the straight portions 11a on both outer sides of the conductive path 11 penetrated by the ferrite beads 12, 12,
The part 11a becomes the inductor _L1 , and the inner straight parts 11b, 11b arranged close to the ferrite beads 12, 12 become the inductor _L2 , and together with the capacitor C between them, an equivalent circuit as shown in FIG. 6 is formed. An LC filter with As described later, ferrite beads 12,
The inductance of the inductor _L2 formed outside the inductor 12 is lower than that of the inductor _L1 , so it does not decrease sharply as the chip becomes smaller. Furthermore, the external shape is similar to that of the conventional chip-type LC.
It is possible to form something almost similar to a filter. The insulating block 15 has a chip-shaped overall shape, holds the output terminals 16, 16 and the ground terminal 17 in predetermined positions, and also holds the ferrite beads 1.
It has the function of protecting 2 and 12. Moreover, the conductive path 11 can be made of a general linear conductor, and the capacitor 13 can also be made with a general lead wire, so that special parts used in a press or the like are not used. chip-shaped LC using common electrical components.
Filters can be configured. [Example] Next, examples and preferred embodiments of this invention will be described with reference to the drawings. As shown in FIG. 1, a linear conductor is used as the conductive path 11, which is bent into a substantially U-shape, and both sides of which are further bent into a U-shape, with straight portions 11a parallel to each other on both sides. , 11a
and 11b, 11b are formed. Further, the space between the inner straight portions 11b, 11b is bent downward to form a recessed portion 18. The ferrite beads 12, 12 are mainly cylindrical ferrite beads with a through hole provided on the central axis, but ferrite beads 12, 12 having other shapes such as a prismatic shape may also be used. This ferrite bead 1
The outer straight parts 11a, 11a of the conductive path 11 are passed through the through holes 2, 12, and the inner straight parts 11a, 11a are passed through the through holes 2, 12, and the inner straight parts 11a, 11a are passed through the through holes 2, 12, and the inner straight parts 11a, 11a are passed through the through holes 2, 12, and the inner straight parts 11a, 11a are passed through the through holes 11a, 11a of the conductive path 11. 11b, 11b are arranged. The capacitor 13 is preferably cylindrical with lead wires 14 and 19 drawn out on the same straight line from both ends, and as shown in FIG.
9 has a recess 18 formed in the conductive path 11.
It is fitted in, connected and fixed with solder 22. In this state, the capacitor 13 is located between and parallel to the two ferrite beads 12, 12. Note that the other lead wire 14 of the capacitor 13 is drawn out parallel to the straight portions 11a, 11a and in the opposite direction. Further, both ends of the conductive path 11 and the tip end of the lead portion 14 are flattened by a roller or the like, thereby preventing the ferrite beads 12, 12 from falling off. Furthermore, as shown in FIG. 3, ferrite beads 12, 12 and a capacitor 13 are buried in an insulating block 15, and both ends of the crushed conductive path 11 and the tip end of the lead wire 14 are drawn out from this insulating block 15. It is. The insulating block 15 is formed by integrally molding an insulating material such as synthetic resin into a rectangular parallelepiped shape by means such as molding. From the end surface of the insulating block 15 from which the ends of the conductive path 11 and the lead wire 14 are drawn out, to one main surface 15a of the block 15 perpendicular to this,
Grooves 20, 20, and 21 are formed corresponding to the widths of both ends of the conductive path 11 and the tip of the lead wire 14. Then, as shown in FIG. 4, the conductive path 11
Both ends of the lead wire 14 and the tip of the lead wire 14 are bent along the surface of the insulating block 15 to form the grooves 20, 2.
0 and 21, respectively, and the insulation block 1
Output terminals 16, 16 and a grounding terminal 17 are formed on the main surface 15a of 5. In addition, the present inventors actually used ferrite beads 12 and 12 with μ = 600 to fabricate two types of chip-type LC filters, large and small, and measured the inductance of inductors L ₁ and L ₂ , as shown in the table below. It was hot on the street. From this result, as the chip size is reduced, the rate of decrease in inductance decreases.
L ₁ is about 76%, while inductor L ₂ is
Approximately 33%. That is, the rate at which the latter decreases is extremely lower than that of the former. Therefore, the inductance
It can be seen that _L2 is particularly effective in securing the total inductance when the chip is miniaturized.

[Effect of idea]

As explained above, according to the present invention, a capacitor having commonly used ferrite beads, a linear conductive path, and a lead wire can be used as is, and a chip shape can be formed without using any specially prepared press parts. An LC filter can be configured. Furthermore, as will be described later, the inductance _L2 formed outside the ferrite beads 12, 12 does not cause a rapid decrease in inductance as the chip becomes smaller. A certain amount of inductance can be ensured. This allows us to create an LC filter that has the same functions and the same shape as a conventional chip-type LC filter, but is easier to manufacture, more durable, and has a relatively high inductance when miniaturized. is obtained.

[Brief explanation of the drawing]

Figures 1 to 3 are perspective views of a chip-type LC filter in a semi-finished state showing an embodiment of this invention;
The figure is a perspective view of the finished appearance of the same filter.
The figure is a front view with the insulating block cut away at the A-A position in Figure 4, Figure 6 is a circuit diagram showing the equivalent circuit of the same filter, and Figure 7 is a conventional example of a chip-type LC filter. FIG. 8 is an exploded perspective view of the filter, and FIG. 9 is a circuit diagram showing an equivalent circuit of the filter. 11... Conductive path, 11a, 11b... Straight part,
12... Ferrite bead, 13... Capacitor, 14... Lead wire, 15... Insulating block,
16...Output terminal, 17...Earth terminal.

Claims (1)

[Scope of utility model registration request] Chip type with inductor and capacitor
In the LC filter, both sides of a linear conductive path 11 bent in a U-shape are further bent outward in a U-shape to form a meandering conductive path 11. The ferrite beads 12, 12 are passed through the ferrite beads 11a, and the inner straight portions 11b, 11b are disposed close to the circumferential surfaces of the ferrite beads 12, 12 and approximately parallel to their central axes, and the same straight portions 11b ,11
One lead wire 19 of the capacitor 13 is connected to the conductive path 11 between the ferrite beads 12 and
12 and a capacitor 13 disposed between them are embedded in an insulating block 15 integrally molded into a chip shape, and both ends of the conductive path 11 drawn out from the insulating block 15 and the other lead wire 14 of the capacitor 13 are connected to each other. The tip side is formed flat, and both ends of the conductive path 11 and the flat part of the lead wire 14 are attached to one surface of the insulating block 15, and output terminals 16, 16 and a ground terminal 17 are formed on the same surface. A chip-type LC filter characterized by: