JPH0129888Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention provides an electronic equipment device for television reception;
In particular, in electronic equipment that switches between an antenna input and a video tape recorder (hereinafter abbreviated as VTR) output and supplies it to a television receiver,
The present invention relates to an electronic equipment device for television reception, in which the VTR output is converted and supplied to an intercarrier oscillation circuit in an RF modulator that supplies the converted output to a television receiver, regardless of the switching.

In general, television receivers (hereinafter referred to as TV receivers) switch between broadcast radio waves received by an antenna and VTR output (hereinafter referred to as TV receivers). (abbreviated as receiving device).

A block diagram showing a conventional structure of the above-mentioned television receiver is shown in FIG. In FIG. 1, an RF modulator 1 converts the output of a VTR into a signal to be supplied to a normal TV receiver when reproducing content recorded on a VTR. The modulator IC 2 includes a video carrier oscillation circuit 3 and an intercarrier oscillation circuit 4, and the video carrier oscillation circuit 3 includes a video carrier oscillator 5, and the intercarrier oscillation circuit 4 includes An oscillator 6 is added for each. Booster amplifier 7 amplifies the antenna input from antenna terminal 8 and supplies the amplified signal to TV receiver terminal 11 via VTR tuner terminal 9 and first switch 10. Note that the first switch 10 is connected to the booster amplifier 7 side and the VTR side when receiving normal broadcast radio waves.
Needless to say, it is switched to the RF modulator 1 side during playback. Also, the second switch 1
Reference numeral 2 supplies power to the video carrier wave oscillation circuit 3 according to the modulator IC 2, and is linked to the first switch 10. That is,
Video carrier wave oscillation circuit 3 is turned on during VTR playback
So to speak, the video carrier wave f _p is output instantaneously and turned off when receiving the antenna input. Terminal 13
is a power supply terminal for the modulator, and terminal 14 is a power supply terminal for the booster. The booster amplifier 7 is constantly supplied with power from the booster power terminal 14. The operation during VTR playback will be described below with reference to FIG.

During VTR playback, as described above, the first switch 10 is connected to the RF modulator 1 side, and the second switch 12 is turned on. Then, the video carrier wave f _p is outputted from the video carrier wave oscillation circuit 3 by the oscillation operation of the video carrier wave oscillator 5 and the video carrier wave oscillation circuit 3 (the video carrier wave
The spectrum of f _p is illustrated in Figure 2A).
Similarly, intercarrier K is output from intercarrier oscillation circuit 4 (the spectrum of intercarrier K is shown in FIG. 2B). Then, in the mixing circuit 15, the video carrier f _p and intercarrier K are mixed,
A sound carrier f _s is generated. Furthermore, the video carrier wave f _p and the audio carrier wave f _s are superimposed to form a bandpass signal.
The spectrum of f _p +f _s sent to filter 16 is illustrated in FIG. 2C). In the bandpass filter 16, the undesired frequency components are removed and the signal F having the spectrum shown in FIG. 2D is sent to the TV receiver terminal 11 via the first switch 10.

The operation of the conventional example shown in FIG. 1 has been briefly described above, but in general, the intercarrier K gradually rises from power-on until reaching a predetermined oscillation frequency. Therefore, as shown by the dotted line in FIG. 2E, which is an enlarged version of the _spectrum shown in FIG. .
As a result, while the audio carrier wave f _s is changing, the color signal changes as shown in FIG. 2E.
A situation occurs in which the frequency band is the same as f _c , which causes an undesirable disturbance in TV receivers, such as the generation of buzz noise. SUMMARY OF THE INVENTION The present invention aims to eliminate the above-mentioned obstacles and to provide an electronic device for television reception that prevents the generation of buzz noise and stabilizes the performance during VTR playback. This will be explained below with reference to the drawings.

FIG. 3 is a block diagram showing the configuration of one embodiment of the present invention. All the symbols in the figure correspond to those in FIG.

The embodiment shown in FIG. 3 is basically the same in structure and operation as the conventional example shown in FIG. That is, in the present invention, power to the intercarrier oscillation circuit 4 is supplied from the booster power supply. Therefore, power is always supplied to the intercarrier oscillation circuit 4, regardless of whether the second switch 12 is turned on during VTR playback. Therefore, the intercarrier oscillation circuit 4 always outputs the intercarrier K as shown in the spectrum shown in FIG. 2B, and even when the first and second switches 10 and 12 are turned on,
The output signal F of the bandpass filter 16 supplied to the TV receiver terminal 11 has stable frequency characteristics as shown in the spectrum shown in FIG. 2D. That is, the transient fluctuation of the audio carrier _fs when the second switch 12 is turned on does not occur, as explained with reference to the spectrum shown in FIG. 2E at the beginning of this specification. Therefore, since the audio carrier wave f _s and the color signal f _c do not overlap, generation of buzz noise is prevented.

As explained above, according to the present invention, power is always supplied to the intercarrier oscillation circuit regardless of whether a switch is turned on to the RF modulator during VTR playback, thereby providing stable oscillation to the intercarrier oscillation circuit. By doing so, it is possible to prevent problems such as buzz noise from occurring.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the configuration of a conventional example of electronic equipment for television reception, and Fig. 2 A to E
1 is a spectrum diagram for explaining the operation of the conventional example shown in FIG. 1, and FIG. 3 is a block diagram showing the configuration of an embodiment of the present invention. In the figure, 1 is an RF modulator, 2 is a modulator IC, 3 is a video carrier wave oscillation circuit, 4 is an intercarrier oscillation circuit, 5 is a video carrier wave oscillator,
6 is the intercarrier oscillator, 7 is the booster
amplifier, 8 is an antenna terminal, 9 is a VTR tuner terminal, 10 is a first switch, 11 is a TV receiver terminal, 12 is a second switch, 13 is a power supply terminal for a modulator, 14 is a power supply terminal for a booster, 15
1 represents a mixing circuit, and 16 represents a bandpass filter.

Claims (1)

[Scope of utility model registration request] It has at least a video carrier wave oscillation circuit and an intercarrier oscillation circuit, and converts the output of a video tape recorder to mix the video carrier wave from the video carrier wave oscillation circuit and the intercarrier wave from the above intercarrier oscillation circuit. A first switch for switching between the output of the high-frequency modulator and the antenna input, and a second switch for supplying power to the video carrier wave oscillation circuit in conjunction with the first switch. In the electronic device for television reception equipped with a switch, power is constantly supplied to the intercarrier oscillation circuit in the high frequency modulator independently of the power supply to the video carrier oscillation circuit by the second switch. An electronic equipment device for television reception, characterized in that it is configured as follows.