JPS5892177A - Television sound reproducer for television receiver - Google Patents

Abstract

PURPOSE:To improve the sound qualities of main and sub-sound, by demodulating the sub-sound signal at a demodulation circuit of the split carrier system, and the main sound signal at the demodulation circuit of the intercarrier system. CONSTITUTION:A main sound signal is obtained from a sound demodulation circuit of the intercarrier system comprising a filter 4, an amplifier 5, a sound signal detection circuit 6, a frequency discrimination circuit 7, and an LPF 8, and sub-sound signal is obtained from a sound demodulation circuit of the split carrier system comprising a filter 12, an amplifier 13, a mixing circuit 14, a local oscillation circuit 15, a ceramics filter 16 and a frequency discriminating circuit 17, via a BPF 18, a limiter circuit 19, and a frequency discriminating circuit 20. Both the signals are applied to a matrix circuit 9, the output is switched into a monaural broadcast or a multiplex broadcast program at a switching circuit 10, and a stereo program and a sound multiplex program at the multiplex broadcast are picked up through switching at a switching circuit 11.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a television audio reproduction device for a television receiver suitable for use in receiving television audio multiplex broadcasting, and particularly to a television audio reproduction device for a television receiver that is suitable for use in receiving television audio multiplex broadcasts, and in particular, is designed to improve the sound quality of the main audio signal and the sub audio signal. This is what I did.

Conventionally, a television audio reproduction device for a television receiver capable of receiving multiplexed television audio broadcasting has used either an intercarrier type or a split carrier type demodulation circuit. In this intercarrier type TV audio playback device, the main audio signal of the TV audio multiplex broadcast is interfered with by noise from the power supply and external noise from the direct deflection system. However, there was a drawback that the sub-audio signal was subject to strong interference from the Eirin signal. -Also, in a split carrier type TV audio playback device, the 8/N ratio is good when the S audio signal is a weak input signal, but the main audio signal is affected by hem noise from the power supply, vertical deflection system, etc. The disadvantage was that it was interfered with by external noise. In this way, conventionally, a single demodulation method was used to demodulate the main audio signal and the "sub audio signal," so depending on the demodulation method used, either the main audio signal or the auxiliary audio signal would be interfered with, causing the main audio Also, there was a drawback that it adversely affected the sound quality of the secondary audio.

In this respect, the present invention is designed to maximize the sound quality of the main audio and sub audio of Kanken TV audio multiplex broadcasting.

Hereinafter, with reference to FIG. 1, an embodiment of the television sound reproduction scissor cover of the television receiver of the present invention will be described.

In FIG. 1, (1) indicates an antenna that receives a television broadcast signal, and the television broadcast signal received by this antenna (1) K is controlled by a channel selection circuit (not shown) K. A tuner (2) K is supplied, and from this, for example, 58.75MH! For example, the image carrier wave component of /, and 5
A signal containing a 4.25 MHI audio carrier component/s is obtained, and this signal is supplied to the Eirin intermediate frequency amplifier (3)K. A K signal is supplied from a part of the output side of the Eirin intermediate frequency amplifier (3) to a filter (4) having a characteristic of extracting only the video carrier wave component and the audio carrier wave component as shown in FIG. The output signal of this filter (4) is supplied to an audio signal detection circuit (6) via an amplifier (5).

This audio signal detection circuit (6) detects the Eirin carrier wave component/.

It consists of a circuit that obtains a beat signal of the audio carrier component /s and a bandpass filter that extracts a signal around 4.5 MHz, which is the frequency difference between /, and /s. The output signal of this audio signal detection circuit (6) is supplied to a frequency discrimination circuit (7) K for frequency discrimination, and the output signal is
A four-pass filter (which is designed to remove frequency components higher than IBKHg, that is, to extract the main audio signal)
8) K is supplied. These filters (4), amplifiers (5)
), the audio signal detection circuit (6), the frequency discrimination circuit (7), and the audio demodulation circuit of the tt intercarrier system.The output of the four-bus filter (8) @Kt The main audio signal is obtained, and the output signal of the voice (8) is sent to this low-pass filter through the matrix circuit (9
) K is supplied and a switching circuit that switches between when one program is not multiplexed (monaural) and when one program is not multiplexed (stereo) The signal is supplied to one of the different audio input terminals E of a switching circuit txt that is switched between audio and other audio situations.

On the other hand, the output signal of the circuit (2) is supplied to a filter (13) which extracts only the audio carrier wave component Ib as shown in FIG.
Only the audio carrier wave component of 25M1b is reduced by t11%.

This audio carrier wave component! @ is mixed circuit 6 through amplifier 0
4. - In case a local oscillation circuit (2) is provided, an oscillation signal of I$4.91MBg is sent to the mixing circuit Q.
4 and the 5 signals are mixed. The output signal of this mixing circuit 4 is filtered by a Cerasec filter which is trapped so that a signal of S liquid number 10.7MH1 is returned, and is converted into an audio intermediate frequency signal and a beat signal E of 7MBm. . The output signal of the third setter filter ←e is then supplied to the frequency discrimination circuit 1 and demodulated. These filter 0, ayg a1% mixing circuit a4, local oscillator I
i circuit a9. The filter shaft and frequency discrimination circuit constitute a split carrier type audio signal demodulation circuit. Then this demodulated signal is 16-4
A bandpass filter (IIK) with a passband of 7KHz
The audio subcarrier is obtained from this, and this power 1
The sub-audio signal is demodulated by frequency discriminator circuit (2). This demodulated sub-audio signal is supplied to the other input terminal of the matrix circuit (9) and the other different type of audio input terminal H of the switching circuit (Iυ).
K is supplied.

Then, one and the other output signals from the matrix circuit (9) are sent to the stereo input terminals B and CK* of the switching circuit aI.
The output signals of one and the other of the switching circuit sections are respectively supplied to the input terminals F and GK of the switching circuit a11.

On the other hand, the signal from the frequency discriminator circuit ai is supplied to the frequency discriminator circuit ai, and when the program is a multiplex broadcast, the control signal subcarrier of 56. (From now on, when the program is in stereo, the stereo control signal of 982.5 Hz is accumulated i, and when the program is in hf! with different audio, it is 11!2.
5H1f) Different types of audio control signals are obtained.

Then, the output signal of the C1 demodulator slope has a passing frequency gB, s
&'s lead filter (c) and 912. lI) 1! are supplied to the lead filters (c) respectively, and the lead filters (
The output signal of C) is passed through the rectifier circuit (C) to the switching circuit (L).
OK is supplied as the switching signal, and the output signal of the reed filter (c) is supplied to the switching circuit alK as the switching signal through the rectifier circuit 1).

When the program selected by the receiving device is not a multiplex broadcast program but a regular broadcast program, there is no control signal subcarrier, so the read filters (C) and (K) cannot obtain signal output. The output signals of the warehouse circuit (c) and (1) are both [a
- level "0" is reached, and both the switching circuit and (Iυ) are switched to the state shown in FIG.

Therefore, at this time, only the main audio signal from the low-pass filter (9) is supplied to the output terminals fin and @ through the switching circuits a and αυ.

If the program is a multiplexed stereo program, the demodulator (2)
A stereo control signal of K 9825Hz is obtained on the output side of , and the distortion is detected by the reed filter@, so the output signal of the rectifier circuit (c) becomes high level "1".
The switching circuit a is in the opposite state to that shown in Figure 1! 1 (state III switched to input terminals B and C@), and the main audio signal and sub audio signal from the matritas circuit (9) are
The left side signal and right side signal obtained by applying the same signal to the output terminal fin and cIsK are obtained through the switching circuits a and aυ, respectively.

Next, if the program is a multiplexed, different audio program, the demodulator (
2) Output WCfjZL5Hxf) A different type of audio control signal is obtained, which is detected by the reed filter K, and therefore the output signal of the rectifier circuit (E) is /S level "1".
The switching circuit aυ is in the state opposite to the state shown in Fig. 1 (input terminal E and HIIK are switched I!), and the output terminal @ receives the main audio signal from the four-bass filter (8). However, the sub-audio signal from the frequency discrimination circuit (2) is obtained at the output terminal @ via the respective switching circuits aυ.

In this way, the circuit can be automatically switched between normal broadcasting, stereo multiplex broadcasting, and different types of audio.

Further, a low frequency amplifier and a speaker (not shown) are connected to the output terminals - and @, respectively.

According to such a configuration, the program being selected is not a multiplex broadcast program, but a regular broadcast program, and the television broadcast signal received by the antenna (11) is transmitted to the antenna (2) K58.
．． Video carrier wave component jp of 75M output! ! A signal containing an audio carrier component s of 4JSMHz is obtained, and this signal is supplied to a filter (4)K via an intermediate frequency amplifier (3). The signal supplied to this filter (4) is converted into an r wave, and only the video carrier wave component/and the audio carrier wave component m are supplied to the amplifier (5). And this amplifier (5)
Both carrier wave components amplified by K and h are supplied to an audio signal detection circuit (6), and from this audio signal detection circuit (6), both images are transmitted /, and! -4.1MHg of difference frequency
An FM audio signal is obtained as a beat signal, which is supplied to a frequency discrimination circuit (7)K for frequency discrimination, and its output signal is supplied to a four-pass filter (8)K. The main audio signal is obtained at the output of this low-pass filter (8),
This main audio signal is obtained at the output terminal (5) and @ via the switching circuit and the switching circuit 6υ, is amplified by a low frequency amplifier (not shown) K''CC, and is supplied to a speaker (not shown) K. In this way, when a regular broadcast program is broadcast, the audio signal is demodulated by the intercarrier type audio demodulation circuit.

Also, when the program is a multiplexed stereo program, the antenna (
The signal received by 1) K is fed to chainer (2) K, from which it is converted into a video carrier component component and an audio carrier component component m.
and are obtained, and these two transport techniques are divided/.

and fs are supplied to the video intermediate frequency amplifier (3)K.

Then, the signal supplied from the video intermediate frequency amplifier (3) is demodulated into the main audio signal by an intercarrier type audio demodulation circuit, similar to the above-mentioned regular broadcast program. Tri-11 circuit (9)K is supplied. In this case, this main audio signal is a sum signal of the right side signal and the right side signal of the stereo broadcast. On the other hand, only the audio carrier component m of I41SMH1 is obtained as an output signal at the output of filter n, and this output signal is amplified through amplifier 0 and supplied to mixing circuit (14). is supplied with an oscillation signal of 4Mh output 2 from the local oscillation circuit aω.Then, in this mixed circuit a4, an oscillation signal of 64°I!!MHj and !$
The signal of the audio carrier component of 415 MHg is mixed and fed to a cellar-built ivy filter (LEK), and the output signal of this 72i ivy filter is the difference in frequency of 10.
A γMHK audio intermediate frequency signal is obtained. This 10.7
The MHz audio intermediate frequency signal is supplied to a frequency discrimination (b) path aη, demodulated by this frequency discrimination circuit any, and this demodulated output signal is supplied to a bandpass filter asK, which converts the audio subcarrier (horizontal synchronization frequency 8 times (approximately 11.5 KHz) is obtained, which is supplied to the frequency discriminator circuit (to) through the sub-circuit circuit (a), where it is demodulated into a sub-audio signal, and is supplied to the matrix circuit (9).

In this case, this sub-audio signal is a difference signal between a left signal and a right signal of stereo broadcasting. Moreover, the demodulated signal from the frequency discrimination circuit aη is a band pass filter k fi 60
A control signal subcarrier of 55.125 KHz is obtained from this. And this +5.1!5KHg
(horizontal periodic frequency) 3.5 times) control No. 1 subcarrier is demodulated by the demodulator (2) K and supplied to the lead filter (2), whereby a 9g2.5Hz stereo control signal is detected. Therefore, the output signal of rectifier circuit 4 is at high level "1".
'', the input terminals B and C are switched to the opposite state from the state of the switching circuit (Ql#m1ll#), and the main audio signal (sum signal) and -audio signal (difference The left signal and the right signal obtained from the output terminal box (2) K are obtained through the switching circuits a and aυ, respectively.The left signal and right signal obtained at the output terminals @ and @, respectively, are are amplified by a low frequency amplifier (not shown) K and supplied to each speaker (not shown).
The main audio signal of the broadcast is demodulated by an intercarrier type audio demodulation circuit, and the sub audio signal is demodulated by a split carrier type audio signal demodulation circuit.

Furthermore, when the program is a multiplexed, heterogeneous audio broadcast program, the main audio signal is obtained as the output of the frequency discriminator circuit in the same manner as in the case of the stereo broadcast program described above, and this output is sent to the input terminal EKK of the switching circuit αυ. Can be supplied. In other words, even in this case, the intercarrier type audio demodulation circuit detects the tonic tone -
The signal is demodulated. Also, the sub audio signal is demodulated by the split carrier type audio signal demodulation circuit as in the case of the stereo broadcast program mentioned above, and is subjected to bandpass filter! The sub-audio signal is demodulated by passing through the Nishiki, Suita circuit (I) and the frequency discrimination circuit (A).The demodulated sub-audio signal is supplied to the input terminal HKK of the switching circuit (+1). Also, the demodulated signal from the frequency discrimination circuit aη is supplied to a bandpass filter C?m)K, and from this!
! A control signal subcarrier of 1.125 KHg is obtained. This control signal subcarrier of s5,1 5KHz is demodulated by faFJK and supplied to the reed filter (c), in which the Jllll voice control signal of C1121, lHg is detected, and therefore the output of the rectifier circuit (c) Since the signal becomes high level "1", the switching circuit (2) enters a state in which it is switched to the input terminals E and H@, which is opposite to the state of 1111111. Then, the main audio signal supplied to the input terminal [i1] of the switching circuit 61) and the sub-audio signal supplied to the input terminal HKK of the switching circuit Oυ are obtained at the output terminals (2) and (2), respectively. The main audio signal and sub audio signal respectively obtained at the output terminals @ and @ are amplified by a low frequency amplifier (SO not shown) and supplied to a speaker (not shown), respectively. In this way, the main audio signal of the different audio broadcast number is demodulated by the intercarrier ψ 70,000 type audio post-1111 circuit, and the sub audio signal is split by the Yaria type audio signal demodulation circuit. Demodulate.

As described above, according to the present invention, the main audio signal is demodulated through 1 kK of intercarrier audio demodulation circuits.

Since the sub audio signal is demodulated by a split carrier type audio signal demodulation circuit, the main audio signal is not interfered with by the noise from the power supply and external noise from the vertical deflection system. At the same time, it is possible to prevent the 8/N ratio from decreasing when the sub-audio 1t-I weak input signal is used. That is, it is possible to improve the sound quality of the main audio and sub audio of the TV audio multiplex broadcast.

It goes without saying that the present invention may have various other configurations without departing from the gist of the present invention.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the television sound reproduction device of the television receiver according to the present invention, and FIGS.
It is a line diagram provided for explanation of a figure. (4) is a filter, (5) is an amplifier, (6) is an audio signal detection circuit, (7) is a frequency discrimination circuit, (8J' is a V-bass filter, (13 is a bandpass filter, and α is an amplifier. , I is a mixing circuit, a is a local oscillation circuit, ae is a cellic filter, and ■ is a frequency discrimination circuit.

Claims (1)

[Claims] It has an intercarrier system audio demodulation circuit and a split carrier system audio signal demodulation circuit, and the main audio signal of the TV audio multiplex broadcast is demodulated by the intercarrier system audio demodulation circuit, and the main audio signal of the TV audio multiplex broadcast is demodulated by the intercarrier system audio demodulation circuit. During the splitting of the sub-audio signal, the audio signal of the Yaria method is used.
A television audio reproducing device for a television receiver that uses demodulation in the GA path as a IIi image.