JP2508368B2 - Dielectric filter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a dielectric filter in which dielectric resonators are capacitively coupled to each other, for example, via a substrate on which a capacitor electrode film is formed. The present invention relates to a structure capable of preventing the adverse effects on the characteristics due to the positional deviation of the substrate and ensuring the positioning of the substrate and the dielectric resonator to improve the workability during assembly.

[Conventional technology]

For example, as a dielectric filter using a plurality of dielectric coaxial resonators, there is conventionally a structure having a structure shown in FIG. The dielectric filter 1 is configured by housing a plurality of dielectric coaxial resonators 2 in a case 3. In each of the dielectric coaxial resonators 2, a through hole 5 is formed in a rectangular parallelepiped dielectric block 4, the inner peripheral surface of the through hole 5 and the dielectric block 4 are formed.
The inner conductive film is formed on the outer surface of each of the parts except the open end surface 4a.
6, the outer conductive film 7 is formed. Further, the tubular body 8a of the coupling terminal 8 is press-fitted into the through hole 5 on the open side end face 4a side of the dielectric block 4, and the connecting piece 8b integrally formed with the tubular body 8a projects outward. ing. Further, a strip-shaped dielectric substrate 9 is arranged on the open side end surface 4a side. A capacitor electrode film 9a is formed on the upper surface of the substrate 9, and each electrode film 9a is provided with a connecting piece 8b of the coupling terminal 8.
Is soldered. Furthermore, input and output terminals 10 are soldered to both ends of the dielectric substrate 9, and each of the terminals 10 projects outward from the opening of the case 3. Further, a solder hole 3a is formed on the contact surface of the dielectric block 4 of the case 3 and the solder 11 filled in the solder hole 3a.
Is electrically and mechanically connected to the outer conductor 7.
As a result, the dielectric filter 1 is formed by capacitively coupling the dielectric coaxial resonators 2 to each other.

[Problems to be solved by the invention]

However, in the conventional filter described above, it has been found that when the dielectric substrate 9 comes too close to the open side end surface 4a of the coaxial resonator 2, the characteristics vary. This is considered to be due to the following reasons. That is, the electric field of the coaxial resonator 2 is not limited to the inside of the resonator 2 (see the solid line in FIG. 9B), but also the electric field from the inner conductive film 6 to the outer conductive film 7 not only on the open side end face 4a. It exists (see the broken line → mark in the figure). When the substrate 9 approaches the open side end surface 4a, the outer electric field is blocked by the substrate 9, and as a result, the characteristics are adversely affected.

To avoid the adverse effect of the board, the connecting piece 8b of the coupling terminal 8
It is conceivable that a gap be provided between the dielectric substrate 9 and the coaxial resonator 2 when soldering to the dielectric substrate 9. However, in the above-described conventional dielectric filter 1, for example, when some external force is applied to the dielectric substrate 9 during mounting, the coupling terminal 8 easily moves inward of the through hole 5,
Since the substrate 9 also moves along with this, there is a concern that the size of the above-mentioned gap changes, resulting in variations in characteristics.

Further, the work of fixing the coupling terminal 8 to the dielectric substrate 9 by soldering while providing the gap is complicated, and there is a problem that workability is poor.

The present invention has been made to solve the above-mentioned conventional problems, and can reliably prevent the dielectric substrate from approaching the end face on the open side by an external force to stabilize the characteristics, and the soldering work of the coupling terminal. An object of the present invention is to provide a dielectric filter that can improve the property.

[Means for solving problems]

According to the present invention, a plurality of dielectric coaxial resonators are arranged in a case, and a dielectric substrate is provided on the open end side of the resonator so that the main surface of the substrate is parallel to the axis of the dielectric coaxial resonator. , The dielectric coaxial resonator is connected to the dielectric substrate through a coupling terminal, and the dielectric coaxial resonators are coupled to each other by a coupling capacitance formed by an electrode film formed on the dielectric substrate. In a dielectric filter formed by rectification, a positioning portion is formed in the case to regulate the distance between the resonator-side end surface of the dielectric substrate and the open-side end surface of the dielectric resonator. A cap is provided between the open side end surface and the resonator side end surface of the dielectric substrate, the cap being 1/3 or more of the thickness of the dielectric substrate and narrower than the width of the substrate in the resonator axial direction. .

Here, the reason why the gap is set to 1/3 or more of the thickness of the substrate is that if the thickness is less than this, the blocking of the electric field cannot be avoided and the effect of preventing adverse effects on the characteristics cannot be obtained.

[Action]

According to the dielectric filter of the present invention, since the positioning portion is formed in the case, and the positioning portion is brought into contact with the substrate and the dielectric resonator to provide a predetermined gap therebetween, the above-mentioned substrate is provided. Even if an external force is applied, the substrate does not move to the end face on the open side, the gap between the two can be kept constant, and the characteristics can be stabilized.

Further, in the present invention, when connecting the coupling terminal and the substrate, the substrate is brought into contact with the positioning portion, and the open side end face of the dielectric resonator is brought into contact with the positioning portion, thereby fixing the dielectric resonator.
Since soldering is performed in this state, the conventional complicated work of positioning while soldering is unnecessary, and the workability can be improved accordingly.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 are views for explaining a dielectric filter according to an embodiment of the present invention, in which the same reference numerals as those in FIG. 9 designate the same or corresponding parts.

The dielectric filter 20 of the present embodiment has five λ / 4 dielectric coaxial resonators 2 arranged in parallel, and the open side end face 4a side thereof is
The dielectric substrate 9 on which the capacitor electrode film 9a is formed is arranged, the connecting piece 8b of the coupling terminal 8 is soldered to the capacitor electrode film 9a, and both ends of the dielectric substrate 9 are inserted.
The output terminal 10 is connected by soldering so that the coaxial resonators 2 are coupled with each other by capacitance, and the basic structure is substantially the same as the conventional one.

The assembly of each dielectric coaxial resonator 2 is a metal case body.
A case cover 22 formed in a box shape is attached to the case body 21. A label 23 is attached to the upper wall 22a of the case cover 22.

In the case body 21, side walls 21b are formed upright on the left and right edges of the bottom wall 21a on which the dielectric coaxial resonator 2 is mounted.
A front wall 21c is formed upright on the front edge of the bottom wall 21a, and the input and output terminals 1 are formed from the left and right openings of the front wall 21c.
0 stands out.

Further, a downward engaging piece 24 is formed by cutting and raising outward on each of the side walls 21b and the front wall 21c, and the engaging piece 24 is formed on the case cover 23. The dowel hole 25 is fitted. Further, solder holes 26, 27 are formed in the bottom wall 21a of the case body 21 and the upper wall 22a of the case cover 22, respectively, at the portions in contact with the coaxial resonator 2, and the solder holes 26, 27 are formed in the solder holes 26, 27, respectively. Is filled with solder, whereby the coaxial resonators 2 are mechanically and electrically connected and fixed.

In the left and right corners of the bottom wall 21a of the case body 21,
The first positioning portions 28, 28 are cut and raised inwardly to be formed upright, and the first positioning portions 28 are in contact with the coaxial resonators 2 at both left and right ends. Further, each solder hole 26 of the bottom wall 21a is
A second positioning portion 29 is formed by bending upward at the front edge of the second positioning portion 29, and each second positioning portion 29 is in contact with the open side end surface 4a of each coaxial resonator 2. Further, a support portion 30 is formed by bending the support portion 30 inward at the front portion of each of the side walls 21b.
Both ends of the dielectric substrate 9 are placed on the upper surface of the supporting portion 30. The front wall 21c has a substantially U-shaped fixing portion 31,
31 is convexly provided inward, and the fixing portion 31 is in contact with the front end portion 9b of the dielectric substrate 9.

The front end surface 28a of the first positioning portion 28 is located slightly forward of the second positioning portion 29, and the rear end surface 9c of the dielectric substrate 9 is in contact with the front end surface 28a. Thus, a cap a is provided between the rear end surface 9c of the dielectric substrate 9 and the open end surface 4a of the coaxial resonator 2, and the gap a is equal to the thickness t of the dielectric substrate 9.
It is set to be 1/3 or more. Specifically, the gap a is about 0.5 mm with respect to the thickness of the substrate 9 of 1 mm.

 Next, the function and effect of this embodiment will be described.

To assemble the dielectric filter 20, first, the dielectric substrate 9 to which the input and output terminals 10 are soldered is placed on the supporting portion 30 of the case body 21, and the substrate 9 is fixed to the first positioning portion 28. It is clamped by the portion 31 to position the dielectric substrate 9 in the front-rear direction.

Next, each coaxial resonator 2 in which the coupling terminal 8 is press-fitted is placed on the bottom wall 21a of the case body 21, the side surface of the resonator 2 is brought into contact with the first positioning portion 28, and the resonator is The open side end surface 4a of the two is brought into contact with the second positioning portion 29, and the coaxial resonators 2 are sequentially arranged. As a result, the coaxial resonators 2 are held by the first positioning portions 28 in the left and right directions, and are positioned in the front-rear direction by the second positioning portions 29. After that, the connection piece 8b of each coupling terminal 8 is soldered to the capacitor electrode film 9a, after which the case cover 22 is mounted, and the solder holes 26 and 27 are filled with solder and fixed.

As described above, according to the present embodiment, the case body 21 is formed with the first and second positioning portions 28 and 29, the dielectric substrate 9 is brought into contact with the first positioning portion 28, and the second positioning portion 29 is provided. Since the open-side end surface 4a of the coaxial resonator 2 is brought into contact with and a predetermined gap a is provided between the two, the dielectric substrate 9 is reliably restricted from moving inward. Even if an external force is applied to the gap a, the gap a can be held, and as a result, the adverse effect on the electric field can be avoided, the characteristic variation can be prevented, and the reliability of the quality can be improved.

Further, in this embodiment, as described in the procedure for assembling the dielectric filter 20, the dielectric substrate 9 and the coaxial resonator 2 are sequentially arranged and positioned on the case body 21, and then the coupling terminal 8 is connected to the capacitor. Since it is soldered to the electrode film 9a, it is possible to eliminate the conventional labor-intensive work of positioning while soldering, and it is possible to improve workability by that amount, which in turn simplifies the work of adjusting the filter characteristics and improves the yield. .

In the above embodiment, the case main body 21 is described as being formed by cutting and raising the first and second positioning portions 28 and 29. However, various modifications can be considered for the shape of the positioning portion of the present invention. To be For example, as shown in FIG. 4, a positioning portion 40 having a substantially triangular shape is cut and raised between the coaxial resonator 2 of the bottom wall 21a of the case body 21 and the dielectric substrate 9, and the width of the positioning portion 40 is formed. You may make it provide a gap.

Further, as shown in FIG. 5, a positioning portion 41 may be formed by cutting and raising the abutting portions of the coaxial resonators 2 and the gap may be obtained by the plate thickness of the positioning portion 41. In this case, if the plate thickness of the positioning portion 41 is thin and the gap is too small, as shown in FIG. 6, a protrusion 41a is formed on the positioning portion 41 and the gap is enlarged by the protrusion 41a. Good. Furthermore, as shown in FIG. 7, the positioning portion 42 may be formed by cutting and raising the side wall 21b of the case main body 21 inwardly, and the same effects as those of the above-described embodiment can be obtained in each of the above-described modified examples.

FIG. 8 shows another example in which the dielectric substrate 9 is fixed, in which a downwardly projecting piece 30a is formed on the upper part of the support part 30 and the substrate 9 is sandwiched between the projecting piece 30a and the support part 30. It is an example.

Further, in the above embodiment, the filter using the dielectric coaxial resonator has been described as an example, but the present invention can be applied not only to the integrally molded dielectric filter but also to the duplexer.

〔The invention's effect〕

As described above, according to the dielectric filter of the present invention, the positioning portion is formed in the case, and the positioning portion forms a space between the dielectric resonator and the substrate that is 1/3 or more of the thickness of the substrate. Since a gap less than the width dimension in the axial direction of the resonator is provided, it is possible to reliably prevent the movement of the substrate due to external force while miniaturizing the entire dielectric filter, and it is possible to stabilize the characteristics and facilitate positioning. There is an effect that workability can be improved.

[Brief description of drawings]

1 to 3 are views for explaining a dielectric filter according to an embodiment of the present invention. FIG. 1 is a perspective view showing a positioning portion thereof, FIG. 2 is a sectional side view thereof, and FIG. FIG. 4 is an exploded perspective view thereof, and FIGS. 4 to 7 are views showing modified examples of the positioning portion. FIGS. 4 (a) and 4 (b) are perspective views, side views, and FIG. 5 is a perspective view thereof, FIGS. 6 (a) and 6 (b) are perspective views and sectional side views thereof, respectively, and FIG. 7 is a perspective view thereof, FIGS. 8 (a) and 8 (b). 9A and 9B are perspective views and sectional views showing another fixing structure of the dielectric substrate, and FIGS. 9A and 9B are perspective views and sectional views showing a conventional dielectric filter, respectively. In the figure, 2 is a dielectric resonator, 4a is an end face on the open side, 8 is a coupling terminal, 9 is a dielectric substrate, 20 is a dielectric filter, 21 is a case body, 28, 29, 40, 41, 42 are positioning parts. , A is a gap.

Claims (1)

(57) [Claims] 1. A plurality of dielectric coaxial resonators are arranged in a case, and a dielectric substrate is provided on the open end side of the resonator so that the main surface of the substrate is parallel to the axis of the dielectric coaxial resonator. And the dielectric coaxial resonators are connected to the dielectric substrate via coupling terminals, and the dielectric coaxial resonators are connected to each other by the coupling capacitance formed by the electrode film formed on the dielectric substrate. In a dielectric filter formed by capacitive coupling, a positioning portion that restricts a distance between a resonator-side end surface of the dielectric substrate and an open-side end surface of the dielectric resonator is formed in the case, and the positioning portion is provided. Between the open-side end surface and the resonator-side end surface of the dielectric substrate, the thickness of the dielectric substrate is
A dielectric filter having a gap of 1/3 or more and narrower than the width of the substrate in the resonator axial direction.