JPS5983479A - Buzz sound preventing device of television receiver - Google Patents

Abstract

PURPOSE:To reduce buzz sound, by inserting respectively a characteristic filter having prescribed characteristic between a tuner and a video intermediate amplifier stage and between the video intermediate frequency amplifier stage and a sound intermediate frequency amplifier stage. CONSTITUTION:A radio wave from an antenna 1 is applied to a tuner 2, and a video signal is obtained from a terminal 13 inputted to a video processing section 7'' including a video intermediate frequency amplifier stage 4 via a filter 3 having the characteristics of A, B. An output of the video intermediate frequency amplifier stage 4 is inputted to a sound processing section 12'' including a filter 15 having characteristics C, E, a sound intermediate frequency detecting beat detecting stage 5, a filter 9 having characteristic of D, a sound intermediate frequency amplifier stage 10 and a sound detecting stage 11 and the sound signal is obtained from a terminal 14. Thus, buzz sound is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention relates to a buzz noise prevention device that minimizes buzz noise in a television receiver.

(B) Background Art A television receiver using a conventional ink carrier system has an image receiving antenna (1), a tuner (2) as shown in FIG.
), first filter (3), video intermediate frequency (VIP)
An amplification stage (4), a video signal processing unit (7) including a beat detection stage (5) for audio intermediate frequency (SIF) detection and a video detection stage (6), an audio trap (8) circuit, and an audio intermediate frequency (SIF)
SIF filter (9) for audio intermediate frequency (SI
'F) Consists of an audio signal processing unit @ including an amplification stage (6) and an audio detection stage 0→, a video signal terminal 03 and an audio terminal 04
The configuration is such that video signals and audio signals are reproduced from each of them.

The above-mentioned configuration is called the so-called intercarrier two-axis detection system, and although the configuration is simple and the price is low, it has the disadvantage that there is a lot of buzzing noise in the audio output of the television receiver.

Therefore, as a method of improving the audio characteristics in order to reduce the buzz sound, as shown in FIG. 2, unlike in FIG. 2 filters (connecting 1G and 1V to each in turn)
A video signal processing section (1') including an IP stage 00 and a video detection stage a71 is connected, and a second VIP amplification stage (g) and an SI
The audio signal processing section (1, 2') including the F beat detection stage 0, the SIF filter (9), the SIP amplification stage α and the audio detection stage (1, 1) is connected, and the video signal terminal (c) and A system has been proposed in which a video signal and an audio signal are obtained from the audio signal terminal α→, and the characteristics of the first filter (3') are as shown in FIG.

The frequency relationship in each channel of the first filter (3) is as shown in Table 1 below.

Table 1 In the previous table, AdjPIX is the video carrier wave of the adjacent channel, S
is the audio carrier, C is the color subcarrier, P is the video carrier, Ad
j SND indicates the audio carrier of the adjacent channel, and each frequency is in megahertz (MHz).

However, the detection method called the quasi-parallel or pseudo-sprint method shown in Figure 2 has the advantage of having less buzz components in the audio signal and less color beat, but it has the disadvantages of a complicated configuration and high price. there were.

(C) Embodiment of the present invention Fig. 4 is a block diagram of the noise prevention device for a television receiver of the present invention, and Figs. , (A) or (B) is the frequency characteristic diagram of the first filter, (C) is the frequency characteristic of the second filter, (2) is AdjPIX is the video carrier wave of the adjacent channel, S is the audio carrier wave, and C is the color. A carrier wave, P indicates a video carrier wave, and AdjSND indicates an audio carrier wave of an adjacent channel.

Table 2 Next, to explain the buzz sound prevention device for a television receiver according to the present invention, in FIG. The signal is applied to the video signal processing section (H) via the filter (3). A frequency characteristic diagram of the SI'F filter is shown. FIG. 5(e) shows a frequency characteristic diagram of the second filter in FIG. 4 when used in a receiving circuit for a television multiplex system with two audio carrier waves, for example, the West German PAL system.

In Fig. 4, the same elements as those in Figs. Wave step (6
), while the audio processing section (12') includes a second filter (a), an SIF beat detection stage (5), an SIF filter (9), an SIF amplification stage 0*, and an audio detection stage 0◇. , (8) shows the audio trap circuit.

Next, in FIGS. 5(a) to (e) and the following table 2, the first filter (3) has the characteristics shown in FIG. 5(a) or (b), for example. An example of this is the West German channel. The output of the VIP amplification stage (4) in the video signal processing section (7) is applied to the second filter (to), where the video component is removed, so the SIF detection circuit (
5) performs beat detection.

This beat-detected signal is applied to the SIF amplification stage Qd via the SIF filter (9) and then to the audio detection stage (11).
) (FM detection for NISC and PAL systems, AM detection for 5ECA and M systems), and an audio signal is obtained from terminal 04.

On the other hand, the output signal of the VIP amplification stage (4) is the audio trap (
8), the video is detected by the video detection stage (6), and a video signal is obtained from the terminal (g), so that the chroma beat component is removed.

In the above case, the second filter OQ in the West German channel example
As shown in Figure 5(c), S: 33.4 M)lz, P: 38.9
It has a bimodal characteristic with a resonance point at Mllz, thereby eliminating video components that cause buzz.

The characteristics of the SIF filter (9) have a single peak characteristic with a center frequency (S) as shown in FIG.

Note that the audio trap (8) is a trap for 33.4 Mn2 in the example of the West German channel mentioned above, and attenuates the audio component.

Next, the frequency characteristics of the second filter (a) used in the receiving circuit of the West German TV audio multiplexing system, which has two audio carrier waves, are as shown in FIG. channel and audio second channel, and these include R+L/2 and L plus the pilot signal (R
is the right component and L is the left component), and the right and left voices are reproduced in the audio demodulation circuit.

(e) Effects of the present invention According to the present invention, in a conventional television receiver, aυ...
-Second filter.

Compared to the intercarrier two-axis detection method, there is less buzzing noise, and compared to the quasi-parallel detection method, the same characteristics can be obtained even though the circuit configuration is simpler, and the configuration is simple and has high quality reception characteristics. A television receiver can achieve this.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a conventional intercarrier two-axis detection type television receiver, Fig. 2 is a block diagram showing a conventional quasi-parallel detection type television receiver, and Fig. FIG. 4 is a block diagram of the buzz noise prevention device for a television receiver according to the present invention, and FIGS. 5 (A) to (E) are characteristic diagrams of the constituent elements used in FIG. 4. shows. Explanation of main drawing numbers

Claims (1)

[Claims] (1) A television receiver comprising a video intermediate frequency amplification stage, a video detection stage, and a video amplification stage, and an audio intermediate frequency amplification stage, an audio detection stage, and an audio amplification stage.
A first filter having an attenuation characteristic with respect to an adjacent video carrier and an adjacent audio carrier is connected between the video intermediate frequency amplification stage and the video intermediate frequency amplification stage, A buzz sound prevention device for a television receiver, characterized in that a second filter having bimodal characteristics at each frequency of an audio carrier and a video carrier is connected, and audio is detected by the audio detection stage.