JPH026663Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to the structure of an LC filter consisting of a coil and a capacitor, and provides an LC filter with extremely good distortion characteristics by selecting the structure and the material of ferrite.

Conventionally, it consists of this kind of coil and capacitor.
The structure of the LC filter is that a drum core is placed on the top surface of a terminal plate made of insulating resin with terminal pins embedded in the bottom surface, winding is applied directly to this, and the terminal lead wire is wired and soldered to the terminal pin. This drum core is covered with a pot core with a male thread on the outer periphery, and the whole is wrapped and fixed in a shield case with a female thread on the side that engages with the male thread, and the capacitor is housed in the recess in the center of the terminal board. The LC filter is configured in this state. Since the drum core used is made of ferrite material, which is mainly made of nickel-singing material, the ferrite core itself has a very high surface resistance and has high insulating properties similar to porcelain, so winding is directly applied to it. However, the coils themselves have poor distortion characteristics, and as equipment becomes more sophisticated, the LC filters used in systems such as pulse code modulation are becoming more and more difficult. Improvements in distortion rate characteristics were required. However, when the material of the ferrite is changed to a manganese zinc-based material, the strain rate becomes very good, but its surface resistance becomes small, and when a wire is directly wound on it, defects such as poor insulation and coil shorts occur frequently. It had the disadvantage of being

The present invention was devised to improve this problem, and will be explained with reference to the drawings. Figure 1 is an elevational cross-sectional view of the LC filter of the present invention, and Figure 2 is its
A cross-sectional view along the −X′ line is shown. In the figure, reference numeral 1 denotes a pot core, which has a cylindrical shape with an opening at the lower end and a ceiling at the upper end, and a cylindrical central core is integrally formed at the center of the interior of the pot core from the ceiling. 2 is a male thread groove provided on the outer periphery, and 3 is an adjustment driver groove. This pot core 1 is made of manganese zinc ferrite. 4 is a hollow bobbin made of synthetic resin having a terminal plate portion and a collar at the upper end, and the core of the pot core 1 is inserted into this hollow portion. A terminal pin 5 is planted on the bottom surface of the terminal plate portion, and a cylindrical capacitor 7 is housed in the recess 6 of the terminal pin 5. 8 is a winding portion and 9 is a shield case. A female thread groove 2' is provided on the side surface of this shield case 9, into which the outer circumferential male thread of the pot core 1 is screwed, and the pot core 1 moves up and down by the rotation of the female thread groove 2'. This means that the

The present invention has the above-described structure, and when the depth from the lower open end of the pot core 1 to its ceiling is L, and the depth from the open end to the lower end W of the winding section is A, the pot core A≧1/3L is always satisfied within the entire range of motion of 1. For this reason, the Q of the winding part of the coil is much higher than that of a normal coil, which is located near the open end of the pot core 1, and is almost the same as that of a conventional drum core and pot core combination coil. Equivalent Q is obtained. Furthermore, since the material of this pot core 1 is made of manganese zinc ferrite, it has better distortion characteristics of about 20 dB or more than coils made of normal nickel zinc or cut-spar zinc materials.
Furthermore, even though the surface resistance, which is a drawback of manganese zinc ferrite, is small, it does not come into contact with the winding portion of the coil, so there are no defects such as insulation defects or shorts. Also, since only one pot core is used instead of the two ferrites of the drum core and pot core as in the conventional case, the cost can be reduced.

As described above, according to the present invention, the cost is reduced, the Q is the same, the distortion rate characteristics are improved, and defects such as insulation defects and shorts are completely eliminated, so the practical effects thereof are great.

[Brief explanation of the drawing]

Figure 1 is an elevational cross-sectional view of the LC filter of the present invention.
FIG. 2 is a cross-sectional view taken along line X-X'. 1... Pot core, 2, 2'... Thread groove, 3...
...Driver groove, 4...Hollow bobbin, 5...Terminal pin, 6...Recess, 7...Capacitor, 8...
Winding part, 9... Shield case.

Claims (1)

[Scope of utility model registration request] A terminal board and a hollow bobbin with a collar are molded into one body, a wire is wound between the collars, a pot core with a core to be inserted into the hollow part of the bobbin is covered, and a male thread for screwing is provided on the outer periphery of the pot core. , cover this with a shield case with a female thread formed on the side surface to be screwed into it, so that the length A from the lower end position W of the winding part to the lower end of the pot core is located deeper than 1/3 of the depth L of the pot core, This is an LC filter characterized by the fact that the material of the pot core is manganese zinc ferrite.