JPS605623Y2 - Multi-stage tuned filter - Google Patents

Description

[Detailed description of the invention] The present invention uses the copper foil surface on the printed circuit board as one side of the metal outer casing that surrounds the resonant circuit, and eliminates the need to provide a partition plate on the printed circuit board. The present invention relates to a multistage tunable filter in which coils are arranged coaxially so as to resonate at the same frequency, and other circuit elements are similarly arranged.

Conventionally, a tank circuit (hereinafter referred to as a resonant circuit) is formed by combining a plurality of tuned coils with a variable capacitance element, and there is no partition plate between each resonant circuit. However, in this case, a multi-stage tunable filter was constructed by surrounding each resonant circuit with a metal case or a shield lid.

Therefore, it has been impossible to configure other amplifier circuits and the like on the same plane as the tuning coil.

In addition, in a filter having such a configuration, a resonant circuit is constructed on a mounting base made of the same metal plate, and its periphery is surrounded by a metal plate to form a sealed structure, so that, for example, When adjusting the degree of coupling with the next stage in each resonant circuit, the shield housing etc. must be completely removed from the mounting base each time. It also had the disadvantage of being expensive.

The present invention improves the drawbacks of the conventional filter as described above, and creates a resonant filter by surrounding the coaxial tuning coil with metal walls on three sides and a double-sided printed circuit board on one side. At the grounding part of the printed circuit board other than the connection part, a part of the electrical closed circuit is created together with the internal casing through the copper foil surfaces on both sides, which are electrically conductive through the through holes, and this closed circuit is connected to the coaxial circuit along with the tuning coil. The present invention provides a multi-stage tuned filter constructed in such a manner that a tuning coil and other circuit elements are held and mutually connected on a copper foil surface which is distributed in a shape of a shape.

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

FIG. 1 shows the external shape of a multi-stage tunable filter 1, its schematic side cross section and side surface state are shown in FIGS. 2a and b, and its disassembled state is shown in FIG. 3.

In FIG. 3, figure a shows a box-shaped metal external housing 2, and the upper surface of the external housing 2 is provided with a plurality of holes 3 for adjusting the variable capacitance element 6. Further, a plurality of tongue pieces 4 for attaching to an external printed circuit board (not shown) or the like are provided at the lower end thereof.

Figure b shows a printed circuit board 5 which is a base for attaching various elements, and on both sides of the printed circuit board 5, there is a patterned copper foil pattern with the circuit within the dotted line in Figure 6 a or b. It is formed as shown in FIG.

In the center of this circuit pattern, a plurality of through holes 21 are provided in pairs in the longitudinal direction for insertion of the terminals of the variable capacitance element 6.
, 2m' are provided, and a through hole 22 for insertion of the through terminal 9 is provided at the end.

Furthermore, the periphery of each independent through hole is surrounded by copper foil for soldering, and the diagonal line part 25 on one side is
The diagonally shaded wide portions on the other surface are each formed as a ground portion.

These grounding parts are formed with a relatively small area ratio to the part forming the signal connection part between each element, and have a copper foil surface 23 forming the grounding part on one surface and a grounding surface on the other surface. As shown in FIG. 7, between the copper foil surface 25 forming the
By providing internally plated through holes 26 at both ends, electrical continuity between both sides is maintained, and the copper foil surface 25 on the other side is kept within a range where it does not come into contact with the inner wall surface of the internal casing 5. and the copper foil surface 23 on one side.
is slightly smaller than the width of the , and is slightly offset from that width.

Figure 0 shows a through terminal 9 that penetrates the printed circuit board 5 and is fixed to a metal internal housing 10 having a U-shaped cross section (side surface) as shown in Figure d, and is similar to the circuit pattern on the copper foil surface. It is electrically connected and outputs a signal to the outside.

On the other hand, a plurality of holes 11 are provided on both sides of the internal housing 10 for adjusting the inductance of the tuning coil, and a plurality of protrusions 12 are provided on the upper part of the inner wall surface for mounting the printed circuit board 5. Further, a tongue piece 13 for mounting on a printed circuit board or the like is provided at the lower end.

Based on the above configuration, the assembled state will be explained next.

First, on the other side of the printed circuit board 5 (FIG. 4a), a tuning coil 8 is installed between each pair of through holes 24 and 24'.
Each tuning coil 8 is mounted coaxially by inserting the terminal of the coil and soldering it to the circuit pattern on one both sides.

Moreover, on one surface of the printed circuit board 5 [FIG. 4b],
The terminal of the variable capacitance element 6 is inserted into each pair of through holes 21 and 21', and by soldering it to the circuit pattern on both sides, it is placed in a positional relationship corresponding to the tuning coil 8. , will be installed in a straight line, and the temporary circuit elements 7 and the like will also be installed at the same time.

This mounted state is schematically shown in FIG. 5.

Next, the printed circuit board 5 with the plurality of tuning coils 8, variable capacitance elements 6, etc. mounted on each surface is mounted on the protrusion 12 of the internal housing 10.

At this time, the through terminal 9 is connected to an insulating material 14 such as glass or resin.
Therefore, after the through terminal 9 is inserted into the through hole 22 in the printed circuit board 5, it is held in a fixed state by the protrusion 12.

After that, the copper foil surface 2 of the ground portion of the printed circuit board 5 is
3 and the internal housing 10, and further solder the through-hole terminal 9 and the copper foil around the through-hole 22. The three parties become completely entrenched.

In this case, the holes 11 of the internal casing 10 are aligned in advance so that they are arranged at the interstage portions of the tuning coil 8.

In order to prevent this stuck state, by further fitting the outer casing 2 in a sealed manner on the opening side of the inner casing 10, that is, in the direction opposite to the side on which the printed circuit board 5 is installed, the printed circuit board 5 can be grounded. The copper foil surfaces 23 and 25 as parts are regarded as one metal wall and are completely sealed, and the hole 3 of the external casing 2 is positioned so as to face the variable capacitance element 6. By arranging the completed multi-stage tuning type P
Wave device 1 will be obtained.

Next, the case of mounting the multi-stage tunable filter having the above structure on an external printed circuit board and the case of adjustment will be explained.

First, a completed multi-stage tunable filter 1 as shown in FIG.
is placed in position on an externally connected printed circuit board (not shown).

At this time, the tongue pieces 4 and 13 are inserted into the printed circuit board in advance in accordance with the positions of the tongue pieces 4 and 13 disposed on the outer casing 2 and the inner casing 10 of the multi-stage tunable filter 1. A through hole is provided to pass through the copper foil forming the ground circuit, and a through hole for the through terminal 9 for signal transmission is similarly provided through the copper foil forming the other signal transmission circuit. It is provided.

Therefore, by soldering these tongue pieces 4, 13 and through terminals 9 to each through hole after Shinto, they are mechanically fixed to each other and connected in terms of electrical circuits, resulting in a multi-stage tuning type. The filter 1 can be easily mounted on a printed circuit board.

On the other hand, when adjusting this mounted state, the variable capacitance element 6 is inserted into the groove in the head of the variable capacitance element 6 using a screwdriver or the like through the hole 3 provided on the top surface of the external housing 2. By rotating it, the capacitance can be easily adjusted in the attached state.

Regarding the tuning coil 8, by removing the solder that forms the connection between the tongue piece 4 of the external casing 2 and the external circuit copper foil, only the external casing 2 can be separated from the printed circuit board. At the rear, a hole 11 provided on the side surface of the internal housing 10
Similarly, the inductance can be adjusted by changing the interval (coupling degree) etc. of the tuning coil 8.

After adjustment, it is only necessary to attach the external housing 2 to the printed circuit board again.

The present invention has constructed a multi-stage tuned filter as described above, so that: (1) the copper foil surface of the double-sided printed circuit board is electrically conductive via the through hole; Since a closed circuit is formed through the shield, the shielding effect is further improved.

In other words, if the copper foil surface that forms the ground part on the other surface and the wall surface of the internal housing are in mere contact, poor contact is likely to occur due to vibration, etc., and in that case, the magnetic flux will change. By offsetting this to a non-contact position and making it electrically conductive with the copper foil surface that forms one surface grounding part using a through hole, 1. While changing the magnetic flux, it can improve the shielding effect. It has been improved.

(2) Since the resonant element has at least a double shielding structure with the drawing foil surface as the grounding part of the printed circuit board, the inner casing, and the outer casing, the shielding effect for the resonant element is further enhanced, and Stable circuit operation by having a positive influence on other circuit elements.

(3) By adopting the above structure, it is possible to eliminate the effects of stray inductance and capacitance due to wiring connections at high frequencies, especially in the VHF band. Capable of blocking cavity current.

(4) Since the common elements and other circuit elements are assembled on the same printed circuit board, the overall assembly is easy and the device can be made compact.

(5) With the above structure, the variable capacitance element can be adjusted through the hole on the top surface without removing the external casing, while the internal The tuning coil can be adjusted through the hole in the housing.

(6) Work efficiency is high because the mounted state can be obtained by simply soldering the tongue pieces provided on the internal and external casings to the external printed circuit board.

It is capable of producing remarkable actions and effects such as.

[Brief explanation of the drawing]

The drawings relate to one embodiment of the present invention, in which Fig. 1 is a perspective view showing the external appearance of a multi-stage tunable filter, Fig. 2a is a schematic side sectional view, and the same figure shows an external casing removed. A side view of the state, and Figure 3 is an exploded perspective view showing the configuration of the multi-stage tunable filter.
Figure 4a shows the external casing, Figure 4 shows the circuit elements mounted on the printed circuit board, Figure C shows the through terminals, Figure 4d shows the internal housing, and Figure 4a shows the circuit elements installed on the other side of the printed circuit board. This figure shows the circuit pattern provided on one side as viewed from both sides of the other side. Figure 5 is a perspective view showing the mounting of tuning circuit elements etc. on the printed circuit board. FIGS. 6a and 6b are diagrams showing an example of a circuit configured in a multi-stage tunable filter,
FIG. 7 is a schematic side view showing how the printed circuit board and the internal casing are fixed. In the drawing, 1 is a multi-stage tunable filter, 2 is an external casing, 3 and 11 are holes, 4 and 13 are tongue pieces, 5 is a printed circuit board, and 6
is a variable capacitance element, 7 is another circuit element, 8 is a tuning coil,
9 is a through terminal, 10 is an internal casing, 12 is a protrusion, 23 and 25 are circuit patterns of a ground portion on a copper foil surface, 26
is a through hole.

Claims (9)

[Scope of utility model registration request] (1) In a resonant filter, the negative side is formed of a printed circuit board, the other side is formed of a metal wall, and a closed circuit is constructed by surrounding a multi-stage tuning coil arranged coaxially. Copper foil surfaces with circuit patterns for the wiring and grounding sections are arranged on both sides of the board, and the copper foil surface for the grounding section is formed with a sufficiently smaller area ratio than the copper foil surface for the signal connection section. A plurality of tuning coils are arranged coaxially on one copper foil side of the printed circuit board, and a variable capacitance element and other circuit elements are arranged on the other copper foil side. A metal internal casing with a U-shaped cross section is made by mounting a printed circuit board with the tuning coil installed side facing inward of the U-shape, and the printed circuit board and the printed circuit board are mounted thereon. A metal outer casing is fitted to the outer periphery of the inner casing of the printed circuit board, and an electrical closed circuit is formed between the grounding copper foil surface of the printed circuit board and the internal casing, while the tuning coil is connected to the printed circuit board. A multi-stage tunable filter characterized by having a double shielding structure with a grounding copper foil surface, an inner casing, and an outer casing surrounding each other. (2) The multi-stage tuned blast wave according to claim (1) of the utility model registration claim, which is provided with a through terminal that penetrates the bottom surface of the internal casing and connects to the copper foil surface of the signal connection portion of the printed circuit board. vessel. (3) The multi-stage tunable filter according to claim (1), which is a registered utility model, in which an electrical conduction path is formed between the grounding copper foil surfaces on both surfaces of the printed circuit board via through holes. (4) The width of the grounding copper foil surface of the printed circuit board on both sides where the tuning coil is installed is made slightly smaller than the grounding copper foil surface on the other side within a range that does not touch the side surface of the internal casing. Scope of Claims for Utility Model Registration Paragraph (1) or Paragraph (
3) The multi-stage tunable filter described in section 3). (5) Utility model registration claim No. 1 in which the grounding copper foil surface of the printed circuit board on which the variable capacitance element is mounted is fixed to the internal casing to form a closed circuit with the same electrical potential. ), (3) or (4). (6) Scope of Utility Model Registration Claims Paragraph (1) or (2) in which a copper foil surface is formed into a circuit pattern so that a tuning coil, an amplifier circuit element, etc. are mounted on the same printed circuit board. Multi-stage tunable filter as described. (7) Scope of Utility Model Registration Claim No.
The multistage tunable filter according to item 1), item (2), or item (5). (8) The multi-stage tuned filter according to claim (1) of the utility model registration, wherein holes for inductance adjustment are provided in the side surface of the internal casing corresponding to the interstage portions of each tuned coil. . (9) The multi-stage tuned blast furnace according to claim (1), wherein a capacitance adjustment hole is provided on the top surface of the external casing in accordance with the mounting position of the variable capacitance element. 0α Utility model registration claim Paragraph (1), Paragraph (8) or Paragraph (9) in which a tongue piece for fixing to an external printed circuit board is provided at the lower end of each of the internal casing and the external casing. Multi-stage tunable filter as described.