KR200176217Y1 - Sound signal demodulation circuit of television tuner - Google Patents

Abstract

The present invention relates to a voice signal demodulation circuit of a television tuner, comprising: an intermediate frequency amplifying unit for amplifying an intermediate frequency signal of a tuner unit, and an audio signal contained in the intermediate frequency signal amplified by the intermediate frequency amplifying unit; In the audio signal demodulation circuit of the television tuner comprising a voice signal demodulation unit for demodulating, the audio signal contained in the intermediate frequency signal of the tuner unit output from the intermediate frequency amplification unit is 4.0MHz, 5.5MHz, 6.0MHz, A band-pass filter for filtering by each frequency band of 6.5MHz and a voice signal corresponding to each of the frequency bands of the 4.0MHz, 5.5MHz, 6.0MHz, and 6.5MHz filtered through the band-pass filter; Since it comprises a switching selector for actively selecting at the time of input and supplying to the voice signal demodulator, P It can be used without any distinction between AL method and NTSC method, so it has an excellent effect to maximize productivity.

Description

Audio signal demodulation circuit of television tuner

The present invention relates to a voice signal demodulation circuit of a television tuner, and more particularly, to filter the voice signal contained in the intermediate frequency signal of the mixing unit by frequency bands of 4.0 MHz, 5.5 MHz, 6.0 MHz, and 6.5 MHz, respectively. The present invention relates to a voice signal demodulation circuit of a television tuner capable of further improving productivity by providing a band pass filter and a switching selector to be supplied to a voice signal demodulator.

In general, the tuner selects a desired high frequency signal from a plurality of high frequency signals induced from an antenna and converts the signal into an intermediate frequency. In this case, the audio signal demodulation circuit of the conventional TV tuner including the tuner performing the function of converting a plurality of high frequency signals generated from the antenna to an intermediate frequency will be described with reference to FIG. 1.

1 is a block diagram showing an audio signal demodulation circuit of a television tuner according to the prior art.

As shown in FIG. 1, the audio signal demodulation circuit of the conventional TV tuner includes a tuner unit 10 for selecting a desired high frequency signal from a plurality of high frequency signals derived from an antenna ANT and converting the desired high frequency signal into an intermediate frequency signal. ), An intermediate frequency amplifier 20 for maximum amplification of the intermediate frequency signal output through the tuner unit 10, and an intermediate frequency of the tuner unit 10 amplified by the intermediate frequency amplifier 20. Filtering through the bandpass filter unit 50 and the bandpass filter unit 50 to pass only the signal corresponding to any one of the 4.5MHz, 5.5MHz, 6.0MHz, 6.5MHz band of the signal in the signal; And a low frequency amplifier 40 for amplifying and demodulating the demodulated signal demodulated by the audio signal demodulator 30.

In this case, the tuner unit 10 includes a high frequency input unit 11 for removing a signal other than a desired channel from a plurality of high frequency signals induced from a feed line of the antenna ANT and selecting only a predetermined desired high frequency signal, and the high frequency input unit. The high frequency amplifying unit 12 which amplifies the high frequency signal of the desired channel output from 11 and the high frequency signal output from the high frequency amplifying unit 12 and the oscillation signal of the local oscillating unit 14 are mixed into an intermediate frequency signal. It consists of a mixing section 13 to convert, the band pass filter section 50 is composed of a resistor (R1) and the LC filter (51).

The operation of the audio signal demodulation circuit of the conventional TV tuner having the above configuration will be described below.

First, when a plurality of high frequency signals are induced from the feed line of the antenna ANT, the high frequency input unit 11 selects only the high frequency signals of the desired channel and supplies them to the high frequency amplifier 12.

At this time, the high frequency amplifying unit 12 amplifies a desired high frequency signal applied from the high frequency input unit 11 and supplies it to the mixing unit 13 to be mixed with the oscillation signal of the local oscillating unit 14.

Thereafter, the mixing unit 13 mixes the high frequency signal of the high frequency amplifier 12 and the oscillation signal of the local oscillator 14 to output the intermediate frequency signal, and the intermediate frequency signal is an intermediate frequency amplifier ( Amplified again in 20) and applied to the band pass filter 50 at the rear stage.

At this time, the intermediate frequency signal of the tuner 10 amplified by the intermediate frequency amplifier 20 is a 5.5MHz audio signal in the case of B / G of PAL, a 6.0MHz audio signal in the case of the I method, In case of D / K mode, it is divided into 6.5MHz voice signal, and NTSC's M mode is 4.5MHz voice signal. Each band pass filter unit 50 corresponding to the voice signal of the band is separately provided to filter the intermediate frequency signal of the tuner unit 10 to be supplied to the voice signal demodulator 30.

Thereafter, the voice signals of the frequency bands that have been demodulated by the voice signal demodulator 30 are amplified by the low frequency amplifier 40 to be finally output.

However, the audio signal demodulation circuit of the conventional TV tuner constituting the above-described configuration and operation includes the PAL method and the audio signal included in the intermediate frequency signal of the tuner unit 10 amplified by the intermediate frequency amplifier 20. In the case of the NTSC system, the bandpass filter unit 50 configured for each frequency band is separately installed and filtered, and then applied to the voice signal demodulator 30 so that the circuit configuration is complicated and productivity is remarkably increased. There was a big downside.

That is, in order to filter the intermediate frequency signal of the tuner unit 10 amplified by the intermediate frequency amplifier 20, a voice signal of 5.5 MHz in case of B / G of PAL, and 6.0 MHz of case of I method. In the case of the voice signal, D / K method, 6.5MHz voice signal, and NTSC M method, because the band pass filter unit 50 corresponding to the 4.5MHz voice signal for each structure is installed separately However, there has been a huge problem of inefficient circuit configuration.

Therefore, the present invention has been devised to solve the above problems, and the object of the present invention is that the voice signal contained in the intermediate frequency signal of the tuner part can be actively supplied to the voice signal demodulator by filtering the frequency band. It is to provide a voice signal demodulation circuit of a television tuner that can be used by mixing the PAL method and the NTSC method by installing a band pass filter and a switching selector.

1 is a block diagram showing a voice signal demodulation circuit of a television tuner according to the prior art;

2 is a block diagram showing an audio signal demodulation circuit of a television tuner according to the present invention;

* Explanation of symbols for main parts of the drawings

10: tuner portion 11: high frequency input portion

12: high frequency amplifier 13: mixing section

14: local oscillator 20: intermediate frequency amplifier

30: voice signal demodulator 40: low frequency amplifier

100: band-pass filter unit 110: 4.5MHz band filter unit

111: first LC filter 120: 5.5 MHz band filter unit

121: second LC filter 130: 6.0MHz band filter unit

131: third LC filter 140: 6.5MHz band filter

141: fourth LC filter 200: switching selector

R1: first resistor R2: second resistor

R3: third resistor R4: fourth resistor

Therefore, the audio signal demodulation circuit of the television tuner according to the present invention for achieving the above object includes an intermediate frequency amplifying unit for amplifying an intermediate frequency signal of a tuner unit, and an intermediate frequency signal of the tuner unit amplified by the intermediate frequency amplifying unit. A voice signal demodulation circuit of a television tuner comprising a voice signal demodulation unit for detecting and demodulating a voice signal contained therein, wherein the voice signal included in the intermediate frequency signal output from the intermediate frequency amplification unit is 4.0 MHz. And a band-pass pass filter unit for filtering by each frequency band of 5.5MHz, 6.0MHz, and 6.5MHz, and the frequency bands of the 4.0MHz, 5.5MHz, 6.0MHz, and 6.5MHz, respectively, filtered through the band-pass filter. And a switching selector for actively selecting a voice signal corresponding to the voice signal and supplying the voice signal to the demodulator. It is done by

In the above configuration, the pass-by-band filter unit for each band, 4.5MHz band filter unit for passing a voice signal of 4.5MHz frequency band, 5.5MHz band filter unit for passing a voice signal of 5.5MHz frequency band, 6.0MHz frequency band It is preferable that a 6.0 MHz band filter section for passing the voice signal of the and a 6.5 MHz band filter section for passing the voice signal of the 6.5 MHz frequency band.

Hereinafter, a preferred embodiment of the audio signal demodulation circuit of the television tuner according to the present invention will be described with reference to FIG.

Fig. 2 is a block diagram showing the audio signal demodulation circuit of the television tuner according to the present invention, and the same name and the same reference numeral will be used together for the configuration having the same function as the conventional configuration.

As shown in FIG. 2, the audio signal demodulation circuit of the television tuner according to the present invention selects a desired high frequency signal from a plurality of high frequency signals derived from the antenna ANT and converts it into an intermediate frequency signal 10. ), An intermediate frequency amplifier 20 for maximum amplification of the intermediate frequency signal output through the tuner unit 10, and an intermediate frequency signal of the tuner unit 10 output from the intermediate frequency amplifier 20. The band-pass pass filter unit 100 for filtering and passing the voice signal included in each of the frequency bands of 4.0 MHz, 5.5 MHz, 6.0 MHz, and 6.5 MHz, and the band-pass filter unit 100 filtered through the band. The switching selector 200 actively selects upon inputting a voice signal corresponding to each of the frequency bands of 4.0 MHz, 5.5 MHz, 6.0 MHz, and 6.5 MHz, and detects the voice signal selected through the switching selector 200. Demodulate It comprises a speech signal demodulator 30, a low frequency amplifier 40 for amplifying and outputting the demodulated signal demodulated by the voice signal demodulation unit 30. The

At this time, the band pass filter unit 100, 4.5MHz band filter unit 110 is composed of a first resistor (R1) and the first LC filter 111 to pass the voice signal of the 4.5MHz frequency band, The 5.5MHz band filter unit 120 including the second resistor R2 and the second LC filter 121 to pass the audio signal of the 5.5MHz frequency band and the audio signal of the 6.0MHz frequency band can be passed. The 6.0 MHz band filter unit 130 including the third resistor R3 and the third LC filter 131, and the fourth resistor R4 and the fourth LC filter 141 to pass a voice signal in a 6.5 MHz frequency band. It consists of a 6.5MHz band filter unit 140 configured as.

Referring to the operation of the audio signal demodulation circuit of the television tuner according to the present invention having the above configuration as follows.

First, when an intermediate frequency signal is output from the tuner unit 10, the intermediate frequency signal is amplified by the intermediate frequency amplifier 20 and then filtered through the band pass filter unit 100 to switch switching unit 200. ) Is entered.

At this time, the intermediate frequency signal of the tuner unit 10 amplified by the intermediate frequency amplifier 20 is a 5.5MHz band filter unit 120 in the case of the B / G system of the PAL, in the case of the I system The 6.0 MHz band filter unit 130 is filtered through the 6.5 MHz band filter unit 140 in the case of D / K, and the 4.5 MHz band filter unit 110 in the case of the M system of NTSC. It is actively selected by the switching selector 200 and applied to the voice signal demodulator 30 at the rear stage.

Thereafter, the voice signal demodulator 30 detects a voice signal in the intermediate frequency signal of the tuner 10 selected by the switching selector 200 and supplies the voice signal to the low frequency amplifier 40. . The voice signal amplified by the low frequency amplifier 40 is finally output through an external output means such as a speaker.

As described above, in the audio signal demodulation circuit of the television tuner according to the present invention, the audio signal included in the middle frequency signal of the tuner unit output from the intermediate frequency amplifier is 4.0MHz, 5.5MHz, 6.0MHz, 6.5MHz, respectively. By configuring the band pass filter and the switching selector to be filtered for each band and actively supplied to the voice signal demodulation unit, there is an excellent effect of maximizing productivity by being able to use a mixture without distinguishing between PAL and NTSC methods.

Claims (2)

An audio signal of a television tuner comprising an intermediate frequency amplifying unit for amplifying an intermediate frequency signal of a tuner unit and an audio signal demodulating unit for detecting and demodulating a voice signal contained in the intermediate frequency signal amplified by the intermediate frequency amplifying unit. In the demodulation circuit, a band-pass pass filter for filtering the voice signal contained in the intermediate frequency signal output from the intermediate frequency amplifying unit for each frequency band of 4.0MHz, 5.5MHz, 6.0MHz, 6.5MHz And a switching selection for actively supplying a voice signal corresponding to each of the frequency bands of the 4.0 MHz, 5.5 MHz, 6.0 MHz, and 6.5 MHz filtered through the band-pass filter to be supplied to the voice signal demodulator. An audio signal demodulation circuit of a television tuner, comprising: a unit. The band-pass filter of claim 1, wherein the pass-through filter unit for each band includes: a 4.5 MHz band filter unit for passing a voice signal in a 4.5 MHz frequency band, a 5.5 MHz band filter unit for passing a voice signal in a 5.5 MHz frequency band, and a 6.0 MHz frequency. A voice signal demodulation circuit of a television tuner, comprising: a 6.0 MHz band filter unit for passing a voice signal in a band and a 6.5 MHz band filter unit for passing a voice signal in a 6.5 MHz frequency band.