KR19980018115U - Hi-Fi VSI's Normal Audio Noise Reduction Circuit - Google Patents

Abstract

The present invention is to remove the normal audio noise of hi-fi VSI to improve the noise characteristics of the normal signal having a frequency characteristic that is relatively weak to the video signal compared to the hi-fi signal when the hi-fi It is about a circuit.

Features of the present invention include a deck having a video head and an audio head installed therein, a video signal processing unit processing a video signal reproduced by the video head, and an on-screen display guide character on an image signal output from the video signal processing unit. OSD for loading data, audio signal processing unit for processing audio signal reproduced from audio head, LPF and audio selection for selectively filtering only normal audio signal among hi-fi audio signal and normal audio signal output from the audio signal processing unit A switch, the deck unit, an audio and video signal processor, and an OSD, and when the audio reproduction mode of VSI is normal, the audio selection switch is switched to control the output of the audio signal processor to be filtered and output through the LPF. It includes microcomputer.

This invention significantly improves the normal audio output of VSI.

Description

Hi-Fi VSI's Normal Audio Noise Reduction Circuit

According to the present invention, when the audio signal is output in a normal state in a hi-fi It relates to a removal circuit.

A typical hi-fi VSI system is designed to listen to audio signals that are listened to with a video signal in stereo. A typical type of a stereo sound system using this hi-fi VSIAL is a hi-fi recording of a stereo broadcast signal received from an antenna. Hi-fi Vsial capable of playing / playing, an FM tuner which will provide stereo sound of a received FM radio to the Vsial as a sound source, a TV receiver for outputting a video signal reproduced by the Vsial, and the high-fidelity V It consists of an audio amplifier that amplifies the stereo signal output from the sial and converts it into a voice signal, and a left and right channel speaker.

The audio signal processing circuit system for recording / reproducing a hi-fi audio signal in such a hi-fi VSI system has a circuit configuration as shown in FIG.

The recording signal processing system of this audio signal processing circuit includes left and right input signal amplifiers 101 and 105 which receive left and right audio inputs from a stereo audio source, noise attenuators 102 and 106 which reduce noise from their outputs, and these noises. Modulators 103 and 107 for modulating the signals provided from the attenuators 102 and 106 into recording signals, low pass filters 104 and 108, recording amplifiers 109, REC / PB (recording / playback) switching switches, and audio heads 110 and 111; ).

In addition, the reproduction signal processing system of the audio signal processing circuit receives pre-amplifiers 112 and 113 for amplifying the signals reproduced from the audio heads 110 and 111 through a recording / playback changeover switch, and the outputs of the preamps 112 and 113. Channel switches, demodulators 115 and 118, dropout detectors 116 and 119, and the head switch pulse generator 125, respectively, for outputting to the respective band pass filters 114 and 117 according to the control output of the head switch pulse generator 125. Sample holders 117, 120, noise attenuators 121, 123, and output amplifiers 122, 124 which perform a sampling operation by the output of?

The audio head 110 is installed with the video heads on the rotating drum to obtain a fast tape speed, unlike the fixed head type standard VSI.

This audio rotating head method solves the problem that the fixed head method has a problem in that the frequency characteristics, wow flutter, etc. are gradually decreased and high quality is not obtained due to the decrease in tape traveling speed due to prolongation.

In other words, the tape speed of home video is about 3.3cm per second in VIEF standard mode and 1.1cm in 3x mode, so it is 1/2 to 1/4 of the speed of 4.8cm of audio cassette tape recorder. Since only the rotating head used for recording and reproducing the video signal is used, the high-fidelity video is used for recording and reproducing the audio signal.

Since the relative speed between the rotating head and the tape at this time is about 6 m per second, the speed is 200 to 300 times higher than that of the fixed head.

If the fixed head relative speed is the speed at which the human is walking, the speed of the rotating head is higher than that of the jet, and accordingly, hi-fi video obtains high-quality sound at the compact disc level.

The V-Hi's Hi-Fi method is to record the audio signal according to the rotating head FM, but since the video signal is recorded on the tape tightly, the audio signal and the video signal must be multiplexed and recorded.

In a hi-fi system, an audio signal and a video signal recording method to be recorded on a video tape have a feature of recording an audio signal and a video signal at different depths in the tape thickness direction.

At this time, the audio signal is recorded in the deep portion of the tape using two dedicated rotary audio heads, and the video signal is recorded in the surface layer portion of the tape according to the conventional video head.

The head structure here is basically four heads by adding two hi-fi dedicated rotating audio heads in addition to the video head.

In the hi-fi method, two audio heads in addition to the video head are installed in a rotating drum, and the audio signal is FM-modulated and recorded. Since the audio head is disposed in front of the tape driving direction, the audio signal It is recorded deeply in the tape thickness direction in advance.

At this time, since the carrier of the audio signal has a lower frequency than the carrier of the luminance signal, the audio head gap is wider than the video head gap and can be magnetized to the deep part of the magnetic layer of the tape.

When recording on a hi-fi VSI system, the video signal is read out so that the video portion of the tape portion of the tape is first erased. In the system, when the audio signal is reproduced, the audio signal layer portion is erased. Since is used, the influence of noise and the like is not a problem.

However, when the video tape is reproduced using the high fidelity, the audio characteristics are remarkably deteriorated when the audio signal is reproduced and output in the normal mode.

The reason is that the audio signal processing in the hi-fi VSI is shared in the output line by being processed in one IC circuit.

In general, compared to hi-fi, which covers the audio frequency range of 20Hz-20KHz, normal is relatively vulnerable to external noise in the high frequency region, especially for video signals around 16KHz.

An object of the present invention is to provide a high fidelity signal for improving a noise characteristic of a normal signal having a frequency characteristic that is relatively vulnerable to a noise component of a video signal as compared to a hi-fi signal when an audio signal is output in a normal state in a high fidelity system. To provide a normal audio noise cancellation circuit of.

Features of the present invention include a deck having a video head and an audio head installed therein, a video signal processing unit processing a video signal reproduced by the video head, and an on-screen display guide character on an image signal output from the video signal processing unit. OSD for loading data, audio signal processing unit for processing audio signal reproduced from audio head, LPF and audio selection for selectively filtering only normal audio signal among hi-fi audio signal and normal audio signal output from the audio signal processing unit A switch, the deck unit, an audio and video signal processor, and an OSD, and when the audio reception mode of VSI is normal, the audio selection switch is switched to control the output of the audio signal processor to be filtered and output through the LPF. It includes microcomputer.

1 is a schematic diagram of an audio signal recording and reproducing circuit of a typical hi-fi VSI.

2 is a detailed circuit diagram of the present invention.

3 is a flowchart illustrating an operation process of the present invention.

* Description of the symbols for the main parts of the drawings *

10 deck portion 13: video signal processing unit

14: OSD16: audio signal processing unit

17: LPF18: Audio Selection Switch

21: micom

Hereinafter, the present invention will be described with reference to the accompanying drawings.

2 is a circuit diagram of the present invention.

As referred to herein, the noise canceling circuit during normal audio reproduction in hi-fi VSI according to the present invention includes a deck unit 10 provided with a video head 11 and an audio head 12, and the video head ( A video signal processor 13 for processing the video signal reproduced in 11), an OSD 14 for loading on-screen display guide text data to the video signal processed and output from the video signal processor 13, An audio signal processor 16 for processing an audio signal reproduced by the audio head 12 and a normal audio signal of a hi-fi audio signal ST and a normal audio signal N processed and output by the audio signal processor 16. LPF (17) and audio selection switch (18) for selectively filtering only the signal, and controls the deck unit (10), audio and video signal processor (13, 16), OSD (14) When the video playback mode is normal, the audio selection switch 18 is switched so that the output of the audio signal processor 16 is connected to the TV receiver through the LPF 17 and the second terminal 20 of the audio selection switch 18. And a microcomputer 21 for controlling the output to the audio terminal.

When described in detail with reference to Figures 3 and 2 attached to the operation and effects of the present invention configured as described above.

First, the video head 11 and the audio head 12 installed in the deck section 10 pick up and reproduce the video and audio signals recorded on the video track and the audio track of the tape, respectively. Done.

The video signal on the tape reproduced by the video head 11 is input to the video signal processor 13, processed, and then transmitted to the video terminal on the TV receiver 15 side.

At this time, on the composite video signal output from the video signal processor 13, text information for displaying the VSI operation guide message on-screen is generated by the OSD 14 under the control of the microcomputer 21, and displayed on the screen of the TV receiver. Will appear.

Meanwhile, the hi-fi or monaural audio signal read by the audio head 12 of the deck unit 10 is input to the audio signal processor 16 and processed under the control of the microcomputer 21.

The audio signal processor 16 outputs the audio signal in monaural (N) or hi-fi (ST) by selection of the microcomputer 21 or automatic switching according to audio mode automatic recognition.

The hi-fi signal component output from the audio signal processor 16 is directly applied to the first terminal 19 of the audio selection switch 18, and the monaural normal audio signal component is passed through the LPF 17 to the audio selection switch. It is applied to the second terminal 20 of (18).

The LPF 17 is a low pass filter having a cutoff frequency characteristic of 16 KHz, and the noise signal component introduced into the monaural audio signal from the video signal is blocked here.

Therefore, when the audio signal output from the audio signal processor 16 is hi-fi, the microcomputer 21 sends a control signal to the selector switch so that the audio select switch 18 is located at the first terminal 19, and then the audio signal processor The output hi-fi signal is transmitted to the TV receiver 15 as it is.

However, if the audio signal output from the audio signal processor 16 is monaural, the microcomputer 21 outputs a switching signal to the second terminal 20 to the audio selection switch 18.

Therefore, the normal audio output of the audio signal processing unit 16 passes through the LPF 17, and after the noise component due to the video signal is removed, the TV receiver 15 through the second terminal 20 of the audio selection switch 18. Will be sent to the monaural audio jack.

On the other hand, the selective filtering of the hi-fi and monaural audio signals by the microcomputer is displayed on the screen of the TV receiver as a video message through the OSD 14, so that the video tape viewer through VSI playback can easily determine the current audio output state. Will be.

As described above, when the audio signal is output in the normal state in the hi-fi VSI system, the noise characteristic of the monaural normal signal, which has a frequency characteristic that is relatively vulnerable to the video signal, is remarkably improved as compared to the hi-fi signal. The unique effect is that it will appear.

Claims (1)

The deck unit 10 provided with the video head 11 and the audio head 12, a video signal processor 13 for processing the video signal reproduced by the video head 11, and the video signal processor 13 OSD 14 for loading on-screen display guide text data into the video signal processed and outputted by the audio signal, an audio signal processor 16 for processing the audio signal reproduced by the audio head 12, and the audio signal. LPF (17) and audio selection switch (18) for selectively filtering only the normal audio signal of the hi-fi audio signal (ST) and the normal audio signal (N) processed and output from the signal processor 16, and the deck unit ( 10), the audio and video signal processing unit 13, 16, the OSD 14 is controlled, and when the audio reproduction mode of VSI is normal, the audio selection switch 18 is switched to output the audio signal processing unit 16. With this LPF (17) And a microcomputer (21) for controlling the output to the audio terminal of the TV receiver through the second terminal (20) of the audio selection switch (18).