JPS5934173Y2 - Chuyuna - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to the structure of a high frequency tuner such as a VHF tuner for television.

Hereinafter, the present invention will be explained in detail by taking the VHF tuner shown in FIGS. 1 to 7 as an example.

In the figure, reference numeral 1 denotes an insulating shaft press-fitted onto the channel switching shaft 25, which insulates the channel switching shaft 25 and into which a channel switching knob is fitted.

For this reason, the cross section of the knob insertion portion of the insulating shaft 1 has a half-moon shape, which prevents the knob from idling easily.

Reference numeral 2 denotes a fine adjustment shaft used for fine adjustment, which is supported by an insulated shaft 1 and is always tilted as shown in FIG. This fine adjustment shaft 2 is always biased so as to be positioned in the direction of the knob.

Further, the intermediate gear 3 passes through a through hole formed in the front plate 5, and is maintained in the state shown in the first figure by the elastic force of the tension spring 4 with points ◯ and ＠ as fulcrums.

Further, the intermediate gear 3 has gear parts 3a and 3b, and the fine adjustment shaft 2
1, the gear portion 3a and the gear 2a provided on the fine adjustment shaft 2 mesh with each other, and at the same time, the gear 3b and the gear portion 19a of the fine adjustment screw (core) 19 mesh with each other.

Further, when the fine adjustment shaft 2 is rotated in this state, the fine adjustment screw 19 moves in the axial direction, changing its positional relationship with the coil 24 and changing its inductance.

The front plate 5 is fixed by the shark part 15a of the frame 15 and the twisted part 20a of the support plate 20, and the bearing 1 provided thereon
7 receives the groove of the channel switching shaft 25 and prevents the shaft 25 from moving in the axial direction.

Further, the front plate 5 is provided with a hole 5a for attaching a tuner and a cut-and-raised piece 5b for hooking the tension spring 4.

Reference numeral 6 denotes a local source insulating plate, on which a local source clip 33 is tightened and fixed by an eyelet 32.

The local insulating board to which the local clip 33 is attached is fixed to a part of the frame 15.

7 is a shield cover which covers the opening of the frame 15, and after inserting the tongue piece 40b formed by bending from the bridge part 40 of the frame 15 formed to cross the opening, twist the tongue piece 40b. Fixed by

As clearly shown in FIG. 2, the shield cover 7 has a large number of bent pieces 7a having spring properties on its outer edge to stabilize the electrical and mechanical contact between the shield cover 7 and the frame 15.

Reference numeral 8 denotes a printed wiring board, on which electrical components constituting a high frequency amplification circuit, a mixing circuit, and a local oscillation circuit are incorporated, and wrapping terminals 37 are further soldered.

9 is a fixed board for switching the switch, the switching circuit is printed, and the coil, capacitor, and
Some resistors are placed.

The fixed board 9 has a round hole 9a into which the switching rotor 26 is fitted.
is open.

A shield plate 10 is provided with a cut-and-raised piece as shown in FIG. 3, and a wire spring 27 is fixed to this part.

Then, with the channel switching shaft 25 inserted through the shield plate 10, the switching shaft 25 and the shield plate 10 are short-circuited via the wire spring 27 to prevent troubles such as turning.

Reference numeral 12 denotes an antenna block filter, the outer surface of which is covered with a metal layer applied by electroless plating, and this metal layer is connected to the ground terminal of the filter 12 to function as a shield case.

Reference numeral 11 denotes a fixed board for switching the switch, which has almost the same structure as the fixed board 9.

Reference numeral 13 denotes a cam plate, which is rotatably mounted on a fixed board 16 for switch switching with a slide plate 14 in between.

A heart-shaped cut groove 13a is provided on the side surface of the cam plate 13, and a cam guide pin 14a provided on the slide plate 14 is fitted into the cut groove 13a.

When the cam plate 13 rotates with the rotation of the channel switching shaft 25, the cam guide pin 14a moves according to the guidance of the kerf 13a, causing the slide plate 14 to move up and down on the fixed base plate 16, so that the cam plate 14 is accommodated in the slide plate 14. Clip 2
8 slides on a fixed contact provided on the fixed substrate 16 to switch the circuit.

Note that this circuit switching is for vHF band reception and UH, F band reception.
Used to switch band reception.

Reference numeral 18 denotes a wire spring for preventing the channel switching shaft 25 from moving in the axial direction with respect to the front plate 5 via the bearing 17. L-shaped hook portions are provided at both ends, as shown in FIG. As shown, this hook portion is attached to a slot in the front plate 5.

21 is a cam board, ■ 12 channels of HF band and UHF
A predetermined shaft torque is obtained by the spring action of a spring plate 34 which has 13 cam ridges for band reception and which is fixed to a preset plate 22 which will be explained in detail later, and which is fixed to the front plate 5 with screws 35.

A conductor plate 23 is fixed to the preset plate 22 by a mold insert, and a coil 24 is fixed by soldering using the terminal portion 23a of the conductor plate 23.

Further, the side surface of the preset plate 22 has a bobbin portion 22a for the HF band reception channel, and the fine adjustment screw 19 moves within the bobbin portion 22a.

Reference numeral 26 designates a rotor for switching the switch, as clearly shown in FIG. will be combined.

Then, as the switching rotor rotates, the slider 29 slides on fixed contacts formed by printed wiring on the fixed substrates 9 and 11, thereby switching the circuit.

30 is a phono jack, and 31 is an insulator that serves to prevent the wrapping terminal 37 from steadying and to prevent dust, and has several holes through which the wrapping terminal passes.

This insulator 31 also serves to prevent solder from penetrating into the interior through the wrapping terminal when the wrapping terminal 37 is wrapped with an external lead and soldered.

36 is a trimmer capacitor whose capacitance is changed by inserting and pulling out a movable electrode made of a flexible printed board 38 into a fixed electrode bent into a U-shaped cross section; and is fixed by soldering.

Reference numeral 8a denotes a hole provided in the printed wiring board 8, which is provided in a circular or square shape in the center of each electrode pattern of an active element such as a field effect transistor, to reduce the capacitance between each pattern and enhance the isolation effect.

40a is a shield piece formed by bending from the bridge portion 40, and extends in the opposite direction to the tongue piece 40b, and the shield piece 40a is soldered to the end of the shield plate 10 that penetrates the printed wiring board. Connected and fixed by.

In the above configuration, the tuner frame 15, the shield plate 1
0. The shield cover 7 and the grounding conductive patterns on the printed wiring board 8 must all be at the same potential, and the inside of the frame 15 defined by the shield plate 8 must be completely shielded from high frequencies. .

However, in order to ground the conductive pattern for grounding of the printed wiring board 8 to the frame 15 at the shortest distance and to obtain stable grounding at high frequencies, the conductive pattern for grounding is soldered to the frame 15 and the shield plate 10. When the shield cover 7 and the printed wiring board 8 are connected together, the space side formed by the shield cover 7 and the printed wiring board 8 is
Since only a portion of the shield plate 10 protrudes (it is impossible to drill a large hole due to the arrangement of the conductive pattern or the strength of the printed wiring board 8), the shield plate 10 is As a boundary, there is no high-frequency separation at all.

For this reason, conventionally, a separate shield piece made of a metal plate is soldered to the printed wiring board 8 or the frame 15 in order to partition and shield the space formed by the shield cover 7 and the printed wiring board 84. It was installed.

However, as mentioned above, it requires a separate metal plate,
The installation is complicated, and since the shield piece and the shield cover 7 do not come into close contact with each other, there is a drawback that the flow of high frequency power fluctuates due to unstable contact between the shield piece and the shield cover.

The present invention has been developed in view of the above points, and a shield piece 40a is formed from the frame 15 and a single bridge portion 40, and the shield cover 7 and the printed wiring board 8 are separated by this shield piece 40a. - While shielding, the shield cover 7 is brought into close contact with the frame 15 by the tongue piece 40b extending from the bridge part 40 in the opposite direction to the shield piece 40a, so that both 7, 15
This ensures stable and reliable contact.

That is, the tongue piece 40b twists its top part and the tongue piece 40b
As a result of bringing the shield cover 7 into close contact with the frame 15 due to the slope 40b-1 (see FIG. 2), both 7
, 15 can obtain stable electrical contact, and together with the fact that the shield plate 10, the grounding conductive pattern 8b on the wiring board 8, and the shield piece 40a are soldered 41, Frame 15, shield plate 10, conductive pattern 8
b. All the shield covers 7 can be in safe contact over the shortest distance, and the spaces A and B within the frame 15 are almost reliably separated in terms of high frequency.

In the above-described embodiment, the shield piece 40a of the bridge section 40 is connected to the shield plate 10, but as shown in FIG. Sometimes I let them do it.

According to the present invention, a bridge section is formed in the frame so as to cross the printed wiring board installed opposite the open surface of the frame, and the shield piece of the bridge section is removed from the printed wiring board. In addition to connecting and fixing the protruding shield plate and/or the grounding conductive pattern on the printed wiring board, the shield cover is tightly attached to the frame by the tongue piece of the bridging part, so the frame, shield plate, shield cover, and grounding are connected to each other. Not only can all of the conductive patterns for use be electrically contacted reliably, but also the space formed by the shield cover and the printed wiring board can be reliably separated by the shield piece.

Further, since the bridge portion is integrated with the frame, there is no need for any separate parts for the shield wall or for suppressing the shield cover.

Overall, this has a remarkable practical effect in that it can provide a tuner with good contact stability, good isolation, and high reliability at high frequencies.

[Brief explanation of drawings]

1 to 5 show a tuner according to an embodiment of the present invention, FIG. 1 is a partially simplified side sectional view, FIG. 2 is an exploded perspective view of the tuner with partially omitted, and FIG. 3 is an exploded perspective view of the tuner. and FIG. 4 is an exploded perspective view of the main part, and FIG. 5 is a side sectional view of the main part showing the bridge part of the frame.
6 and 7 relate to other embodiments of the present invention, in which FIG. 6 is a side sectional view of a main part, and FIG. 7 is a sectional view taken along the line X--X in FIG. 6. 7... Shield cover, 8... Printed wiring board, 8b... Conductive pattern, 10...
...Shield plate, 40...Bridge part, 40a.
...Shield piece, 40b...Tongue piece, 15
······frame.

Claims (1)

[Scope of utility model registration request] A printed circuit board is installed in the frame so as to face the open surface of the tuner frame, and the shield piece of the bridge portion of the frame that crosses the open surface is attached to the end of the shield plate that penetrates the printed circuit board and/or the printed circuit board. Connected and fixed to the conductive pattern, partitioning the inside of the frame with a shield plate and a shield piece, and having a tongue piece extending from the bridge portion in the opposite direction to the shield piece, and fitting into the frame so as to cover the open surface. A tuner characterized by a shield cover that is tightly attached to the frame.