JPH0231832Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a tuner board that includes extremely high frequency bands such as UHF.

(Conventional technology and its problems) Conventionally, in receiving circuits for extremely high frequency bands such as UHF, because the frequency is high,
Coupling between circuit components and with other receiving circuits is likely to occur, and the front end portion is usually housed in a shield case and mounted on the tuner board.

On the other hand, most tuners are usually capable of receiving multiple bands, and reception circuits corresponding to each band are mixed on the tuner board. For example, when covering the UHF front end with a shield case, it occupies a large space compared to other components on the tuner board. In the past, coupling was prevented by separating coil parts and the like that were likely to be coupled as much as possible and by devising relative mounting positions.
However, as devices become smaller, tuner boards become smaller and components are forced to be placed closer together.
These bands also tend to cause bonding between component parts, which has become a more important problem than before.

(Purpose of the invention) The present invention was made to solve the above-mentioned problems, and is a tuner board that prevents coupling between circuit components on the tuner board by using a shield case attached to the tuner board. Our goal is to provide the following.

(Summary of the invention) In a tuner that can receive multiple bands including extremely high frequency bands such as UHF, the front end related to the high frequency band is housed in a shielded case to form a unit, and this front end unit can be used with other When mounting the circuit components on the tuner board together with the circuit components, circuit components such as coils that are likely to be coupled among the circuit components other than the front end on the tuner board are arranged so that they are located on both sides of the shield case. By doing so, the tuner board prevents coupling between components outside the shield case on the tuner board, allowing each component to be placed close to each other.

(Example) Fig. 5 to Fig. 8 show an example of a small multiple variable capacitor used in the tuner of the present invention, Fig. 6 is a top view, and Fig. 5 is a line B-B' in Fig. 6. FIG. 7 is a sectional view showing the state in which it is attached to the front end board 20, and FIG. 7 is a side view as viewed from the direction of arrow A in FIG. 6.

In each figure, 1 is a variable capacitor main body, and 2 is a polycover. Trimmer capacitors 3a to 3d are arranged on the upper surface of the variable condenser main body 1, and can be adjusted through holes on the upper surface of the polycover 2.

Between the top plate 4 and bottom plate 5 of the variable capacitor main body 1, there is a UHF station variable capacitor section UO from above,
UHF tuned variable condenser section UA, AM tuned variable condenser section AA, VHF (and FM) tuned variable condenser section FVA, AM station variable condenser section AO, VHF (also FM) local variable condenser section
They are arranged in a superposed state in the order of FVO, and are provided with square pillars 6a to 6d and pins 7a to 7d which also serve as electrodes and are inserted into these pillars.
Post 8a supporting the UHF variable condenser section,
8b and pins 9a and 9b.

Each variable condenser section can be operated by a common metal rotor shaft 10 which is disposed between an upper surface plate 4 and a lower surface plate 5 so as to be freely openable. A rotor plate 11 is attached to each variable condenser section, and stator plates 12 coated with insulation are alternately interwoven with the rotor plates on the pillars 6a to 6d and 8a, 8b facing the rotor plate group of each variable condenser section. It is fixed in this state.

In the AM, VHF (and FM) variable condenser section, each stator plate 12 is inserted into the column to which it is attached and is electrically connected to pins 7a to 7d that fix each variable condenser section. The downwardly protruding portions 71a to 71d of the bottom plate 5 of 7d to 7d serve as attachment terminals to the main board 20.

Regarding the UHF variable condenser section, as is clear from FIG. 8 showing the C-C′ cross section in FIG. They are not connected to the fixing pins 9a, 9b of the stator plates 8a, 8b, and the extensions of the stator plate 12 directly protrude to the side of the variable condenser section to serve as mounting terminals 13a, 13b for mounting on the circuit board. In other words, 13a is the variable condenser section UO from the UHF station.
Among the terminals, 13b is the terminal of the UHF tuned variable condenser section UA.

In addition, grounding shield plates 14 and 15 are arranged on the mutually opposing surfaces of the upper plate 4 and the lower plate 5, respectively, and a grounding terminal 14a is integrally formed on the side edge of the shield plate 14, and the grounding terminal 14a is integrally formed on the side edge of the shield plate 14. The shield plate 15 has a ground terminal 15a on the side edge.
15b is provided by being integrally bent and protruded downward by holding portions 5a and 5b formed on the side edges of the lower surface plate 5.

On the other hand, UHF variable condenser sections have a high reception frequency and are highly susceptible to coupling due to stray capacitance between each variable condenser section.
Unlike other variable condenser sections, it is difficult to place them in the same space without a shield. Therefore
UHF variable condenser section and other AM, VHF (combined)
FM) In order to prevent coupling due to stray capacitance between the variable condenser sections and between the local variable condenser section UO and the tuned variable condenser section UA in the UHF variable condenser section, ), and local variable condenser section UO and synchronized variable condenser section
Shield plates 14, 16, 1 are installed between the UA and the UA.
7, 15 are arranged, and shield plates 16, 17
Ground terminals 16a and 17a are also integrally formed on the side edges and protrude to the side of the variable condenser in a mutually overlapping state.

Therefore, the UHF variable condenser section UO,
The UA is shielded from other variable condenser sections by shield plates 16, 17, and 15 to prevent coupling between other sections due to stray capacitance.

Also, since the terminals of the UHF variable condenser section protrude to the side of the variable condenser and do not pass through other sections or intersect with other terminals, the terminals of the UHF variable condenser section protrude to the side of the variable condenser, and do not cross other terminals. It can be sufficiently separated from the terminals 71a to 71d of the section, and coupling due to stray capacitance between the terminals can be effectively avoided.

In addition, the terminals of the UHF variable condenser sections UO and UA are not extended downward, but are made to protrude to the side of the variable condenser, and are connected to the UHF front end board 20 on the side of the variable condenser, thereby making the terminals themselves shorter. It is extremely effective in the high frequency UHF band because it can reduce the lead inductance of the terminal.

This small multiple variable capacitor has a UHF variable condenser section on the side as shown in Figure 5.
Terminal 1 is attached to the circuit pattern 201 of the UHF front end board 20, which constitutes the circuit related to UO and UA.
3a, 13b, 14a, 16a, and 17a are attached by soldering. As a result, the variable capacitor 1 and the UHF front end board 20 are integrated into a unit.

Incidentally, on the UHF front end board 20, as is clear from FIGS. 2 and 4, there are coils L ₁ to L ₅ related to the UHF variable condenser sections UO and UA.
Various electronic components are attached, such as a resistor R, an attachment terminal 21 to a tuner board 40, which will be described later.

Also, on the periphery of the UHF front end board 20,
When incorporating it into the shield case 30 described later,
Protrusion 20 for fixing inside shield case 30
a to 20c are formed.

In this way, it is possible to use a small multiple variable capacitor even in extremely high frequency bands such as the UHF band, but when it is actually incorporated into electronic equipment such as a tape recorder, the side surface of the variable capacitor without a shield plate is Problems still remain, such as noise caused by static electricity from devices, mechanisms, switches, etc., coupling with nearby components, and vibrations caused by the sound pressure and magnetic flux of the speaker that cannot be completely eliminated by the polycondenser cover.

In the present invention, as described below, the shield case 3 for shielding the front end board 20 is
Solved by 0.

The shield case 30, as shown in FIG.
The front-end board 20 is made up of a front plate 31 that is the component mounting side, a back plate 32 that is the back side, and a side plate 33 that covers the side surfaces.Furthermore, the portion of the front plate 31 corresponding to the mounting position of the variable capacitor 1 is Variable capacitor shield case 3 that covers the protruding part of variable capacitor 1
4 is placed.

This shield case 30 is assembled so that the front plate 31 and the back plate 32 are fitted to the side plates 33 from the front and back, and the front end board 20 to which the variable capacitor is attached has protrusions 20a to 20c on its periphery.
The notches 32a to 32c of the back plate 32 and the side plate 33
It is designed to be fixed within the shield case 30 by being held between the two. Each plate is fixed at its contact portion by soldering or the like. In addition, the variable capacitor shield case 34 is inserted into the notch 31a from the back side of the surface plate 31 before attaching the surface plate, and the protrusions 34b, 34
c and 34d (not shown) are attached by soldering to the back surface of the top plate 31.

In addition, the front plate 31, the back plate 32, the side plate 33, and the shield case 34 for the variable capacitor are equipped with adjustment devices so that the coils _L1 to _L5 on the front end board 20 and the trimmer capacitors 3a to 3d of the variable capacitor 1 can be adjusted from the outside. Holes (notches) 31b to 31e, 32
d, 33a to 33c, 34e, and 34f are formed, and as shown in FIG.
0 is assembled, a screwdriver or the like can be inserted through each hole to adjust each adjustment tube place.

In addition, the surface plate 31 that constitutes the shield case 30
The side plate 33 not only shields the front and side surfaces of the front end board 20, but also shields the coil components L 1 to ₁ on the front end board 20 when the front end board 20 is attached, as shown in FIG. Partition plate 31f inserted between _L5 etc.
33d to 33h are formed to prevent coupling between the coil components on the board.

That is, looking at variable condenser 1, the variable condenser itself was only provided with interstage shield plates 14, 16, and 17 between UHF variable condenser sections UA and UO and other variable condenser sections, as described above. However, when the front end board 20 is housed in the shield case 30, the side surfaces of the variable capacitor 1 are shielded by the variable capacitor shield case 34, the partition plate 31f of the front plate 31, and the partition plate 33g of the side plate 33, respectively. Therefore, it is possible to prevent coupling between the UHF variable condenser section, the tuned variable condenser section UA, the local variable condenser section UO, and other variable condenser sections and circuit components.

Therefore, since both the variable capacitor 1 and the front end board 20 are shielded by the shield case 30, it is possible not only to prevent the above-mentioned coupling but also to prevent noise due to static electricity generated from moving parts such as mechanisms and switches. In addition, the sound pressure of the speaker, which could not be prevented with a polycover,
A strong metal shield case can completely block the effects of magnetic flux.

In addition, in each figure, the protrusions 33i, 3 on the lower edge of the side plate 33
3j and a protrusion 34a on the lower edge of the variable capacitor shield case 34 are terminals for attaching the shield case 30 to a tuner board 40, which will be described later.

With the above configuration, the UHF front end unit is completed, and each unit has VHF, FM,
It can be attached to the tuner board 40 on which a receiving circuit such as AM is configured.

FIG. 1 shows a state in which a UHF front end unit containing a UHF front end board 20 housed in a shield case 30 is mounted on a tuner board 40. As shown in FIG.

The UHF front end includes terminal 21 of the front end board 20 and terminals 71a to 71 of the variable capacitor 1.
d, 15a, 15b, and the terminals 33i, 33j, 34a at the lower edge of the shield case 30 are mounted on the circuit pattern 401 of the tuner board 40 by soldering them together with other parts.

On the tuner board 40, a bar antenna 41,
Components of the receiving circuit other than the UHF band, such as the connection terminal 42, as well as resistors, capacitors, and coils, are attached, but as the tuner board becomes smaller and the mounting density of components increases, each component is mounted closer together. For example, VHF and FM, rather than particularly high frequency bands such as the UHF band,
Even in the band, coupling between the tuning (or antenna) coil LVa and the local oscillator coil LV ₀ is likely to occur, and some kind of shielding measures are required in this area as well.

In this invention, we focused on the fact that the UHF front end unit occupies a relatively large space on the tuner board 40, and we focused on the fact that the UHF front end unit occupies a relatively large space on the tuner board 40. generator coil lvl ₀
Arranged so that they are located on both sides with the shield case 30 of the UHF front end unit in between,
The shield case 30 is used as a shield plate to prevent coupling between the tuning stage and the local oscillator stage of the VHF (and FM) receiving circuit. This makes it possible to prevent coupling between parts even if close arrangement of parts is unavoidable.

(Effects of the Invention) As described above, according to the tuner board of the present invention, in a tuner capable of receiving multiple bands including high frequency bands such as UHF, which is normally placed in a shielded case, the tuner board of the present invention can be used. When attaching the high-frequency band shield case to the tuner board together with other circuit components, among the other circuit components on the tuner board other than the shield case, parts that are likely to be coupled, such as coils, should be placed on both sides of the shield case. The structure is designed to prevent each circuit component from being coupled to each other, so even if the mounting density of circuit components increases due to the miniaturization of circuit boards due to the miniaturization of tuner equipment, it is possible to prevent each circuit component from being coupled to each other. They can be placed close together without any problems.

In other words, the shield case for front ends such as UHF is used not only to shield the circuit inside the case, but also as a shield wall between other circuits by utilizing its external shape, so there is no need for a special configuration and it saves space. It is extremely effective both in terms of performance and cost.

[Brief explanation of drawings]

Each figure shows an example of the present invention, and Figure 1 is a UHF
Figure 2 is an exploded perspective view showing the configuration of the UHF front end unit; Figure 3 is a plan view showing the front end unit mounted on the tuner board;
The figure is a perspective view of the external appearance of the shield case, and Figure 4 is
The plan view of the UHF front-end board, Figure 5 is the 6th part of the small multiple variable capacitor used in the tuner of the present invention.
6 is a top view of the variable condenser, FIG. 7 is a side view taken from the direction of arrow A in FIG. 6, and FIG.
It is a C′ cross-sectional view. Explanation of symbols, 1... Variable capacitor body, 11... Rotor plate, 12... Stator plate, 14
~17... Shield plate, 20... UHF front end board, 31... Shield case, 31...
Front plate, 32...Back plate, 33...Side plate, 34
...Shield case for variable condenser, UO...UHF station source variable condenser section, UA...UHF tuned variable condenser section, L ₁ to _{L 5} ...Coil, VL ₀ ...
VHF station coil, VLa...VHF tuning coil.

Claims (1)

[Scope of utility model registration request] In a tuner board on which a front end unit, which is a front end unit that is made into a unit by housing a front end related to a high frequency band such as UHF in a shield case, is attached together with other circuit components, the circuit components other than the front end on the tuner board are By arranging circuit components such as coils that are likely to cause coupling in the tuner board so that they are located on both sides of the shield case, coupling between the circuit components on the tuner board can be prevented. A tuner board characterized by: