JPS5924181Y2 - ceramic filter - Google Patents

Description

[Detailed description of the invention] This invention relates to a ceramic filter such as a ladder-type ceramic filter. Specifically, in a ceramic filter that uses a sealing plate and a sealing material such as resin in the sealing structure, the sealing material houses a ceramic resonator. This prevents the ceramic resonator from entering the internal space and adversely affecting the vibration of the ceramic resonator.

Generally, for ceramic filters that adopt this type of sealing structure, the sealing material such as resin filled on the outside of the sealing plate of the housing opening flows into the internal space of the housing that houses the ceramic resonator. without adhering to the ceramic resonator.
It is required that the vibration of the ceramic resonator is not suppressed.

For this reason, in the past, high viscosity resins were used as sealing materials,
Conventionally, a sealing material was applied between the sealing plate inserted into the opening of the housing and the inner surface of the housing to close the gap, and then filled with sealing material, but it had the following drawbacks: was there.

(1) When using a high viscosity sealing material with low fluidity,
It is difficult to uniformly fill the sealing material, making automation difficult, and bubbles are likely to form inside the sealing material, resulting in poor airtightness and poor insulation.

(2) The sealing plate is molded to be smaller than the diameter of the opening of the housing so that it can be easily inserted into the opening of the housing, and a considerable gap is created between the housing and the sealing plate, resulting in high viscosity. Even if a sealing material is used, it is not possible to prevent the fluid from flowing into the internal space of the casing.
Although there is not enough inflow to adhere to the ceramic resonator,
Air bubbles remain in the sealing material that has flowed into the internal space,
This may cause defects.

(3) When sealing the gap between the sealing plate and the housing with a sealing material such as silicone resin and then filling it with sealing material, two steps of sealing work are required, and the application of the sealing material is also required. Since it has to be done manually, the workability is poor and it is unsuitable for mass production.

As described above, all conventional sealing structures have various drawbacks, and a solution to these problems has been desired.

The present invention solves these conventional drawbacks,
Insert a film larger than the opening of the casing together with the sealing plate into the opening of the casing, and completely close the gap between the casing and the sealing plate with the film to prevent the sealant from flowing into the internal space. It was prevented.

Below, ceramic filters according to the present invention are shown in Figures 1 to 3.
DESCRIPTION OF THE PREFERRED EMBODIMENTS A ladder-type ceramic filter according to an embodiment of the present invention shown in the drawings will be explained as an example.

FIG. 1 shows a sectional view of a ladder-type ceramic filter according to an embodiment of the present invention, and FIG. 2 shows the structure of its main parts.

In the figure, 1 is a housing with an open top surface, and a cushioning material 2, a plurality of ceramic resonators 3, and an electrode plate 4 that electrically connects the ceramic resonators 3 to each other are housed in the housing 1. Further, a lead terminal 5 is electrically connected to the electrode plate 4 and drawn out to the outside.

Reference numeral 6 denotes a sealing plate that closes the opening of the housing 1. A film 7 such as a polyester film having a thickness of 50 μm, which is larger than the opening of the housing 1, is superimposed on the sealing plate 6. 7 is placed inside the housing 1, and is inserted into the opening of the housing 1 together with the sealing plate 6.

Further, the peripheral edge of the sealing plate 6 is in contact with a stepped portion 1a provided on the inner surface of the housing 1 near the opening via the film 7.

A solder 8 closes the gap between the lead terminal 5 and the sealing plate 6 and fixes the lead terminal 5.

Reference numeral 9 denotes a sealing material filled on the outside of the sealing plate 6 inserted into the opening of the housing 1, and this sealing material 9 is a low-viscosity liquid epoxy resin.

Here, as the film 7, a polyester film with a thickness of 50 μm was used, but in addition, various plastic films such as polypropylene film, nylon film, polystyrene film, polycarbonate film, polyvinyl chloride film, cellophane film, etc. Films such as paper, rubber, cloth, and even adhesive tapes can be used, and the material, thickness, etc. of the film may be determined depending on conditions such as heat resistance and chemical resistance.

In addition, as the sealing material 9, acrylic, polyester,
Liquid sealants such as urethane-based sealants can be used.

According to the ceramic filter of the present invention having the above configuration, when the film 7 is inserted together with the sealing plate 6 into the opening of the housing 1, the peripheral part of the film 7 is bent along the inner surface of the housing 1, and the housing is closed. The gap between the body 1 and the housing 1 is closed in close contact with the inner surface of the body 1, so that even if the sealing material 9 is filled, it does not flow into the internal space in which the ceramic resonator 3 is housed.

At this time, the film 7 is disposed on the lower surface of the sealing plate 6, that is, on the inside of the housing 1, but it may be disposed on the upper surface of the sealing plate 6 depending on the case.

Furthermore, since the gap between the sealing plate 6 and the lead terminal 5 is closed with solder 8, the sealing material 9 does not enter through the gap, but if the solder 8 is not needed, the sealing plate 6 is covered with a film. 7 is laminated, and the film 7 is connected by the lead terminal 5.
By breaking through and inserting the film 7, the film 7 also comes into close contact with the lead terminal 5, and the lead terminal 5 and the sealing plate 6
It is possible to prevent the sealing material from flowing in between.

Furthermore, as a method of providing a step near the opening of the casing 1, in addition to using the casing 1 provided with the step 1a, as shown in FIG. Possible means include using the open end of the inner casing 11 as the stepped portion 12.

As described above, according to the ceramic filter according to the present invention, the following effects can be obtained.

(1) The film can completely close the gap between the casing and the sealing plate, which prevents the sealing material from entering the internal space of the casing, making it possible to obtain products with stable quality. .

(2) Since a low-viscosity sealing material can be used, automatic filling of the sealing material is possible, and air bubbles are not generated within the sealing chamber, making it possible to improve airtightness and insulation.

(3) A step is provided near the opening of the casing, and the sealing plate is brought into contact with the step along with the film, so the sealing effect due to the film being in close contact with the inner surface of the casing and the sealing plate
It is possible to perform a double sealing effect by contacting the parts, and it is possible to obtain a stable and reliable sealing effect.

As described above, the ceramic filter of the present invention is an excellent product that enables automation of sealing, improves productivity, and stabilizes quality.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the internal structure of a ladder-type ceramic filter according to an embodiment of the present invention, Fig. 2 is an enlarged sectional view showing the main structure of the filter, and Fig. 3 is another embodiment of the invention. FIG. 2 is a cross-sectional view showing the internal structure of a ladder-type ceramic filter according to the present invention. 1...Housing, la, 12...Step part, 3
... Ceramic resonator, 6 ... Sealing plate, 7 ... Film, 9 ... Sealing material.

Claims (1)

[Scope of utility model registration request] In a ceramic filter having a sealing structure in which a sealing plate is inserted into the opening of a housing housing a ceramic resonator and a sealing material is filled on the outside of the sealing plate, a step is provided inside the housing near the opening. and a laminated plate of a sealing plate and a film larger than the opening of the housing is inserted into the opening of the housing, and the peripheral edge of the plate is brought into contact with the stepped part. filter.