JPH0124987Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an extraction coil for an oscillator, and more specifically, it is a wire or plate material that is inserted into a printed circuit board, extracts the oscillation output, etc. by inductive coupling, and transmits it to the adjacent mixing circuit. It concerns the extraction coil of the oscillator that is formed.

As an RF converter incorporated in a transmitting device for transmitting television signals, the one shown in FIG. 1 is conventionally known. In the figure, a video signal is applied to a video signal input terminal _Vi , clamped by a clamp circuit 1, and then subjected to AM modulation in a mixing circuit 2. On the other hand, the audio signal is applied to the audio signal input terminal Si, amplified in the amplifier circuit 3, and then sent to the FM modulator 4.
The signal is subjected to FM modulation at the mixing circuit 2, and further mixed with a video signal in the mixing circuit 2, and then guided to the output terminal To.
A carrier wave for AM modulating the video signal is generated by an oscillator 5 having an LC resonant circuit. Usually, the carrier wave oscillator can be switched by a variable capacitor, and the oscillation output is outputted to the AM modulation circuit of the mixing circuit 2 by the extraction coil or extraction terminal.
Modulated.

Next, FIG. 2 shows part of the video carrier wave oscillator 5 and mixing circuit 2 in FIG. The structure and operation will be described in detail with reference to FIG. 3, which shows the position in a perspective view. Oscillator 5 is
A variable capacitor 5b is held through the casing 5g of the RF converter, and its capacitance changes as the variable capacitor 5b rotates, thereby resonant line 5a, resonant capacitor 5c, and oscillation element 5d. The resonant frequency of the oscillation circuit constituted by the above is changed over a predetermined frequency range. The oscillation output generated by the oscillator 5 is extracted by an extraction coil 5e arranged substantially parallel to the resonance line 5a, and a balanced modulation transformer 2a and a modulation diode 2 arranged adjacent to the extraction coil 5e.
In b, the video signal is AM modulated. In such a conventional arrangement of circuit components, the extraction coil 5e
Since the connection between the extraction coil 5e and the balanced modulation transformer 2a is made by a pattern provided on the back side of the printed circuit board 6, it is not possible to insert a ground pattern between the extraction coil 5e and the balanced modulation transformer 2a,
In particular, there are drawbacks such as the inability to balance or adjust the modulation depth in the UHF band.

The present invention solves the above-mentioned conventional drawbacks and
The object of the present invention is to provide an oscillator extraction coil that can balance and adjust the modulation degree of an RF converter without variation, especially up to the UHF band.

According to the present invention, such an object is to provide an extraction coil made of a wire or a plate material and a ground pattern provided between an oscillation circuit and a mixing circuit on a substrate, and to connect both circuits to the extraction coil. This is achieved by providing a bridge between the ground patterns and the extraction coil of the oscillator, which bridge is arranged in a crossing manner over the ground pattern.

Hereinafter, the present invention will be described in detail with reference to the embodiment shown in FIGS. 5 to 8. In the figures, parts that are the same as or corresponding to the conventional example shown in FIGS. 1 to 4 are designated by the same reference numerals. . In FIG. 5, an oscillator housing 5g partially indicated by a chain line includes a variable capacitor 5b suspended through the housing 5g, a resonance line 5a disposed on the side of the variable capacitor 5b, and a resonance line 5a disposed on the side of the variable capacitor 5b. A resonant capacitor 5c connected to the line 5a and disposed on the inner wall of the casing 5g and an oscillation element 5d arranged at a corner of the casing 5g are arranged. As is clear from the figure, these members are arranged on the surface of the printed circuit board 6. The housing 5g further includes an extraction terminal parallel to the resonance line 5a.
That is, an extraction coil 5e is arranged. The extraction coil 5e is formed of a plate or wire and includes a bridge portion 5e' extending outward from the housing 5g. The extraction coil 5e is connected to the balanced modulation transformer 2a via the pattern 6a by its bridge portion 5e'. A grounding pattern 6b is provided on the back surface of the printed circuit board 6 below the bridging portion 5e' of the extraction coil 5e, and is designed to sufficiently ground the oscillator 5 and the balanced modulation transformer 2a. The balanced modulation transformer 2a is further connected to a modulation diode 2b. By arranging the ground pattern 6b, the RF converter can prevent variations and adjustments in the modulation degree.
It will be possible to perform this without any variation up to the UHF band.

Here, the shape of the extraction coil 5e will be described in detail. The conventional extraction coil 5e has an appearance as shown in FIG. 4, which has a portion 5f to be inserted into the printed circuit board 6. On the other hand, the extraction coil 5e used in this embodiment shown in FIG. 5 has an appearance as shown in FIG.
a, and a ground pattern 6b from the opposing portion.
The portion 5 has a bridging portion 5e′ extending over the portion 5.
f' is inserted into the printed circuit board 6 and connected to the balanced modulation transformer 2a through the pattern 6a.

FIG. 7 shows another embodiment of the present invention, in which the extraction coil 5e is inserted into the substrate 6 within the oscillator housing 5g in order to stably maintain the mutual position of the extraction coil 5e. 5f and a portion 5f' connected to the balanced modulation transformer 2a. This portion 5f' forms the end of the bridging portion 5e' as shown. With this configuration, the extraction coil 5e is inserted into the substrate 6 at both ends, resulting in extremely good stability.

As stated above, according to the present invention, a bridge section is provided in the extraction coil of the oscillator, and the oscillation circuit and the mixing circuit (balanced modulation transformer) are connected by the extraction coil and the bridge section.
As a result, a ground pattern can be provided on the printed circuit board between the transmitting circuit and the mixing circuit, and by providing the ground pattern, the balance and adjustment of the modulation degree of the RF converter can be made This makes it possible to provide an extraction coil for an oscillator that can be used without any variation up to the band, thereby providing an oscillator extraction coil that is highly effective in improving the adjustment efficiency and performance of an RF converter.

[Brief explanation of the drawing]

Figures 1 to 4 are for explaining a conventional example, in which Figure 1 is a block diagram of an RF converter, and Figure 2 is a circuit diagram showing part of the video carrier oscillator and mixing circuit shown in Figure 1. , FIG. 3 is a perspective view showing the mutual positions of the variable capacitor of the oscillator, the extraction coil, and the balanced modulation transformer, FIG. 4 is a perspective view showing the external appearance of the extraction coil, and FIG. FIG. 6 is a perspective view showing the external appearance of the extraction coil used in the embodiment shown in FIG. 5, and FIG. 7 is a perspective view showing the external appearance of the extraction coil of another embodiment. 2... Mixing circuit, 5... Oscillator, 5e... Extracting coil, 5e'... Bridge section, 6b... Earth pattern.

Claims (1)

[Scope of utility model registration request] An extraction coil made of cotton material or plate material and an earth pattern formed between the oscillation circuit and the mixing circuit are provided on the substrate, and the extraction coil is provided with a bridge portion that connects the two circuits, and this An extraction coil for an oscillator, characterized in that a bridge portion is arranged in a crossing state across the ground pattern.