JPH0611643Y2 - Local oscillator circuit device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a local oscillator circuit such as a television tuner, and more particularly, to facilitating the manufacture of a severe oscillator requiring a resonance frequency accuracy.

2. Description of the Related Art The local oscillation circuit of a television tuner requires adjustment of the oscillation frequency after assembly. This adjustment is performed by, for example, CA
In the case of a local oscillation circuit for a second mixer of a TV (cable television) converter, it is necessary to adjust the oscillation frequency with extremely high precision, and at the same time, high stability is required in its humidity resistance property. 1-97
No. 626 has the following configuration.

A local oscillation circuit of a conventional CATV converter will be described with reference to the drawings.

FIG. 3, FIG. 4, and FIG. 5 are a sectional view, a perspective view, and a circuit diagram, respectively, of a local oscillation circuit section of a conventional CATV converter. Disc type capacitors 14 and 17 having a hole in the center on the metal plate 26, and the resonance coil 13 inserted in the hole.
The resonance circuit is assembled, and the moisture resistance is improved as compared with that assembled on a printed circuit board.

Further, the center of the resonance coil 13 is set to the chassis base 2
2 has a structure in which the screw 12 as a core fixed to the support plate 27 attached to and from which the screw 12 comes in and goes out, and by adjusting the screw 12 from the outside through the through hole 23 provided in the chassis base 22, highly accurate frequency adjustment is possible. I am trying.

Further, one leg of the resonance coil 13 extends under the metal plate 26 through the central electrode hole of the disc type capacitor 17, and its tip is inserted into the printed board 24 at the same time when the metal plate 26 is mounted on the printed board. It is connected to the circuit above (Fig. 5).

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention By the way, in the above-mentioned screw adjustment method, (1) the oscillation frequency varies due to the variation in the relative position of the resonance coil and the screw during assembly, and the adjustment range using the screw may be exceeded. Get out.

(2) Due to the clearance between the central electrode hole of the disk capacitor mounted on the metal plate and the insertion leg of the resonance coil, the resonance coil tilts forward, backward, leftward, and rightward, and when assembled with the printed circuit board, the board of the metal plate The pitch between the insertion leg and the substrate insertion leg of the resonance coil tends to vary.

Therefore, there is a problem that the workability of assembling is deteriorated.

In order to solve the above problems, the local oscillator circuit device of the present invention has at least a metal plate having a cutout hole and a tab trimmer for rough frequency adjustment formed on the metal plate. A resonant circuit flat plate capacitor attached to the flat plate capacitor and a resonance line mounted on the flat plate capacitor, and the resonance line is a strip-shaped metal plate. )
It is formed by bending and has electrode portions attached to the flat plate capacitor at substantially both ends, and at least one end has a connecting portion extending from the electrode portion and connected to a printed circuit board through a cutout hole of the metal plate. In addition, the subassembly is connected to a printed circuit board.

Action According to the above configuration, (1) the strip-shaped resonance line facilitates positioning with a jig.

(2) Since the electrode portion is formed on the resonance line, the structure is self-supporting on the upper electrode surface of the disk capacitor, so there is no tilt in the vertical and horizontal directions, and the relative position with the screw is easy to manage by a jig.

(3) Since it is connected to the printed circuit board by the connecting portion extending to the resonance line made of the strip-shaped metal plate, the pitch between the metal plate and the insertion leg can be easily managed unlike the conventional spiral coil.

(4) Further, in the present invention, it is possible to roughly adjust the variation of the oscillation frequency due to the variation of the electrical characteristics of the assembly and the circuit parts by the tab trimmer cut and raised from the metal plate.

As a result, it becomes possible to improve the assembling accuracy, and especially the workability of assembling on the printed board and the workability of adjustment are improved.

Embodiment An embodiment in which the present invention is applied to a local oscillation circuit of a CATV converter will be described with reference to the drawings.

FIG. 1 is a circuit diagram, and FIG. 2 is a perspective view of a main part assembly.

In the figure, 10 is an amplifier circuit mainly composed of a transistor 9. The LC resonance circuit C which is the main part of the present invention
Is composed of a resonance line 113, plate capacitors 114 and 117, a coarse frequency adjustment tab trimmer 11 and a screw 112.
Reference numeral 19 is a circuit for supplying an operating voltage + B to the transistor 9, and 18 is an AFC circuit including a variable capacitance diode 16. However, the screw 112 for finely adjusting the frequency from the outside of the shield base is arranged on the side opposite to the tab trimmer 11 with respect to the resonance line 113.

FIG. 2 shows a sub-assembly in which the LC resonance circuit C of the local oscillation circuit is mounted on a metal plate and a state in which the sub-assembly is mounted on a printed circuit board 124 in which other circuit parts are mounted. 124 is an amplifier circuit centered on the transistor 9,
Reference numeral 126 denotes a printed circuit board on which the operating voltage supply circuit 19 and the AFC circuit 18 are mounted. Reference numeral 126 denotes a metal plate which is a base body of the sub-assembly, and is connected to the printed circuit board 124 by the downwardly bent insertion portions 126a of the four corners. The flat type capacitors 114 and 117 are mounted on the metal plate 126 by soldering. Punched with strip-shaped copper plate,
The bent resonant line 113 is a flat plate type capacitor 114, 117.
Electrode part 113b, 1 formed by coplanar bending on the upper electrode of the
13b, each of which is soldered and fixed on the metal plate 126 through these capacitors.

Further, the resonance line 113 has a connecting portion 113a whose tip is bent down at a right angle to the metal plate surface on the electrode portion side of the flat plate type capacitor 117, and is inserted into the printed board 124 through the notch hole 122 of the metal plate 126. And is connected to the circuit of the transistor 9.

Further, 11 is a tab trimmer for frequency rough adjustment cut and raised from the metal plate 126, and a fine adjustment screw 112 (not shown in FIG. 2) is arranged on the opposite side of the tab trimmer 11 with respect to the resonance line 113. The resonance frequency can be finely adjusted from outside the shield case. In this embodiment, the fine adjustment screw is not assembled in the sub-assembly C but assembled in the shield case, but it can also be assembled in the sub-assembly as shown in FIG. 3 of the conventional example.

According to the above-mentioned configuration, since the resonance circuit is composed of the metal strip, the positioning in the sub-assembly on the metal plate becomes easier as compared with the conventional one using the linear coil. Further, similarly, the connection portion with the printed circuit board can be easily positioned, and the workability of incorporating the sub-assembly into the printed circuit board is improved.

Furthermore, a tab trimmer for rough adjustment of characteristics is provided, which facilitates the characteristic adjustment work.

Effects of the Invention As described above, according to the present invention, the resonant circuit section is sub-assembled on the metal plate for the purpose of improving the characteristics of the local oscillation circuit of the converter and improving the reliability (especially temperature and humidity resistance). Since the assemblability of objects is improved and the characteristic adjustment work is facilitated, a converter with excellent characteristics can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a local oscillator circuit device according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of a main part of a local oscillator circuit device according to an embodiment of the present invention. 3 is a sectional view showing a conventional structure, FIG. 4 is a perspective view thereof, and FIG. 5 is a circuit diagram thereof. 113 …… Resonance line, 113a …… Connection part, 126 …… Metal plate, 11 …… Tab trimmer, 114,117 …… Plate type capacitor, 122 …… Notched hole, 124 …… Printed circuit board.

Claims (1)

[Scope of utility model registration request] Claim: What is claimed is: 1. A metal plate having a cutout hole and a cut-and-raised dove trimmer, plate capacitors arranged on both sides of the cutout hole on the metal plate, and a metal strip electrically connected and attached through the plate capacitor. A printed circuit board having a strip resonance line and a circuit board having circuit components, and a printed circuit board having a wire connection portion integrally extending from one attachment portion of the plate strip capacitor of the metal strip resonance line through the cutout hole. Local oscillator circuit device connected to the circuit parts of.