JP2546328Y2 - VTR audio signal recording circuit - Google Patents

Description

[Detailed description of the invention]

[0001]

The present invention relates to a method for receiving audio signals and video signals of audio multiplex television broadcasting (hereinafter referred to as audio broadcasting), demodulating the signals and recording them on a magnetic tape, and then converting the recording signals to another tape. The present invention relates to a circuit for preventing malfunction of an audio signal related to tape editing when copying to a magnetic tape.

[0002]

2. Description of the Related Art Since an audio system for sound broadcasting is stereo broadcasting or bilingual broadcasting, a discrimination signal is superimposed on a broadcasting signal corresponding to each broadcasting, so that conventional sound broadcasting can be received. A magnetic recording and reproducing device such as a VTR
A method of detecting the discrimination signal, switching the audio system, and automatically recording a predetermined audio signal on a predetermined track of a magnetic tape has been performed.

[0003] That is, a technique for recording an audio signal based on a multi-sound broadcast on an inclined track is disclosed in, for example, Japanese Patent Application Laid-Open No.
As described in Japanese Patent Publication No. 512 (G11B5 / 027), a recording / selection changeover switch is manually switched in response to reception of a bilingual broadcast, and an audio signal selected based on the switch position is displayed on a tilt track. In addition, when a stereo discrimination signal of a broadcast signal is detected, a stereo signal is forcibly recorded on an inclined track regardless of the switching position of the recording selection switch.

[0004] Also, the applicant of the present application has a Japanese Utility Model Application No. 60-39.
No. 07 (G11B5 / 027) discloses that when recording a multi-audio broadcast on an audio track provided in the longitudinal direction of a magnetic tape, a left channel mode, a right channel mode, and a synthesis mode of the left and right channels are selected. Providing mode command means for selecting one, recording the signal selected by the mode command means on the audio track when receiving bilingual broadcasts, while receiving the stereo broadcast signal by the mode command means based on the stereo command signal It is shown that regardless of the setting mode, the mode command is invalidated and the monaural signal is automatically recorded.

As described above, in order to cope with the reproduction operation of the VTR which does not have the audio HiFi signal processing circuit, that is, records and reproduces the audio signal only in the longitudinal track of the magnetic tape, the sound multi-broadcast discrimination signal is provided. In this way, a HiFi audio signal is multiplex-recorded on a video track (inclined track), and a predetermined signal (that is, monaural when stereo broadcast is received) is automatically recorded on an audio track (horizontal track) provided in the longitudinal direction of the magnetic tape. HiF that records signals and records the main audio when bilingual broadcasts are received)
iVTRs are generally awarded.

However, since the discrimination signal is not simultaneously recorded on the magnetic tape on which the audio signal of the multi-tone broadcast is recorded, the original magnetic tape recorded as described above is copied to another magnetic tape (tape dubbing). ) Is not discriminated, and in particular, an audio signal in which a main audio (Lch) and a sub audio (Rch) are mixed is recorded on a horizontal track of a magnetic tape obtained by tape dubbing bilingual audio. You.

For this reason, the reproduction of the horizontal track sound of the magnetic tape after the duplication becomes substantially impossible, and the reproduction of the inclined track sound is impossible (for example, dropout) by utilizing the horizontal track. There is a disadvantage that it cannot be reproduced.

Also, tapes related to audio multiplex recording, such as loss of compatibility between magnetic tapes due to loss of identity between audio signals recorded on an original magnetic tape and audio signals recorded on a copied magnetic tape, and the like. The challenge was to solve dubbing.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has been described in which duplication is performed by dubbing from an original magnetic tape on which a bilingual signal of audio multiplex broadcasting is recorded to another magnetic tape. When making a tape, the fact that the bilingual voice has a higher signal level of the conversational voice than the signal level of the background voice is used, and further, a main voice (for example, Japanese) and a secondary voice (for example, English) are used. By utilizing the fact that each audio signal has a phase shift, the phase shift of the reproduced audio of the bilingual audio signal recorded on the original magnetic tape is detected to determine whether the sound is stereo monaural or bilingual. When a stereophonic sound is discriminated, a sound signal in which the main sound (Lch) and the sub sound (Rch) are mixed is used. When a bilingual sound is discriminated, the main sound (Lc) is used.
The object of the present invention is to record the audio signal of h) on a horizontal track according to the discrimination output.

[0010]

Therefore, according to the present invention, an audio signal recording circuit of a VTR for dubbing an audio multiplexed signal recorded at a predetermined recording position on a magnetic tape to another magnetic tape has an Lch (or Lch) of a reproduced audio signal. Main) Voice, Rch
First and second input terminals to which respective signals of (or secondary) audio are respectively input, and respective signals of Lch (or main) audio and Rch (or secondary) audio from the first and second input terminals are mixed. And a phase inverting means for comparing the audio signal from the first input terminal based on a predetermined reference level and inverting the phase, and a signal level generated by the phase inverting means and the second input terminal. Comparing means for deriving a discrimination signal based on the audio multiplexed signal by comparing the level of the audio signal with the audio signal from the audio signal, and selecting an audio signal from the mixing circuit and an audio signal from the first input terminal according to the discrimination signal. And a sound recording circuit for performing signal processing to record an audio signal selectively output from the switch circuit on a horizontal track provided in a longitudinal direction of the magnetic tape. Toss .

[0011]

According to the above arrangement, the reproduced audio multiplexed signal recorded on the inclined track of the magnetic tape is discriminated by the phase inversion means and the comparison means as to whether or not it is a bilingual sound, and according to the discrimination output. The main audio signal is recorded on the horizontal track of the magnetic tape. In this way, the duplication of the audio signal recorded on the horizontal track when dubbing from the original magnetic tape to another magnetic tape is performed using the same audio signal as the audio signal recorded on the original magnetic tape. Therefore, compatibility between magnetic tapes is maintained.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a circuit block diagram for explaining the principle of the embodiment of the present invention.

In the figure, 1 is an input terminal for an Lch (or main) audio signal, 2 is an input terminal for an Rch (or sub) audio signal, and 3 is a Hi for FM-converting an Lch (or main) audio signal.
FM audio recording circuit 4 and Rch (or sub) audio signal
This is an AF recording circuit using a general known technique including signal processing by a HiFi audio recording circuit 5 for conversion.
The AF signal generated by the F recording circuit is applied to rotating heads 6 and 7 which sequentially and alternately scan inclined tracks on a magnetic tape (not shown). Since the method of recording the AF signal on the inclined track is not directly related to the present invention, detailed description of the embodiment will be omitted. 8 is an Lch (or main) audio signal and an Rch
A mixing circuit 9 for mixing (or sub) audio signals, a switch circuit 9 for switching between the output of the mixing circuit and an Lch (or main) audio signal in accordance with a discrimination output described later, and a voice circuit 10 for processing the switch output as a recording signal. This is a recording circuit, and the audio signal created here is applied to a fixed head 11 that scans a horizontal track on a magnetic tape (not shown). 12 is a phase inversion means for comparing the input audio signal with a predetermined reference level and outputting a level signal obtained by inverting the phase of the audio signal;
Reference numeral 13 denotes comparison means for comparing the level of the phase-inverted level signal with the Rch (or sub) audio signal to derive a discrimination output.

The audio signals input to the input terminals 1 and 2 are
The HiFi audio recording process is performed by the AF recording circuit 3, and the FM audio is recorded on the inclined track. On the other hand, a mixed audio signal output from the mixing circuit 8 (Lch in stereo / monaural)
And Rch), or the main (Lch) audio signal in bilingual audio is selected by a switch circuit 9 controlled based on a discrimination signal obtained by discriminating the phase of the input audio signal, and a voice recording circuit 10 is selected. And the voice is recorded on the horizontal track.

The phase of the audio multiplex signal is determined by a phase inverting means 12 and a comparing means 13. That is, by comparing the input audio signal L with the predetermined reference level 14 by the phase inverting means 12, a small-level signal based on a background signal other than the bilingual audio conversation signal is cut, and the phase of the input audio signal L is reduced. Is obtained from the output of the phase inversion means 12.

The level signal La is inputted to one input of the comparing means 13 as a reference value to be compared, and the input sound signal R is inputted to the other input of the comparing means 13 so that the output of the comparing means 13 is obtained. As a result, a discrimination signal output La-R based on the input signal level comparison of the audio multiplex signal is obtained. This discrimination signal output (La-R) is zero in stereo broadcasting / monaural broadcasting (because the signal phases of Lch and Rch are substantially the same), and is not zero in bilingual broadcasting (Lch and Rch). Will be out of phase). By switching and controlling the audio signal to be recorded on the horizontal track in accordance with the state of the discrimination signal output La-R, a discrimination signal (for example, a pilot signal such as a stereo instruction signal, a bilingual instruction signal, etc.) based on multi-sound broadcasting is controlled. ) Enables the duplication (tape dubbing) of an audio multiplex signal onto a magnetic tape without depending on the same.

FIG. 2 is a circuit block diagram of one embodiment of the present invention. In FIG. 2, the same parts as those of FIG.

The FM-demodulated audio signals (L, R) input to the input terminals 1 and 2 are rectified into direct current (DC) level signals through rectifier circuits 15 and 16, respectively.
The output of the well-known operational amplifier (op-amp)
Is input to a + input (non-inverting input terminal) of a phase inverting circuit 17, and an output of the rectifying circuit 16 is input to a-input (inverting input terminal) of a comparing circuit 18 including a well-known operational amplifier.

Then, a predetermined reference level (a reference voltage level for inverting the phase of the input audio signal L) is applied to a negative input (inverting input terminal) of the phase inverting circuit 17 from the VREF 19.
Is input, the level of the input audio signal L is compared based on the reference level, and the phase inversion circuit 17 outputs an inverted DC level signal whose phase has been inverted and amplified with respect to the input audio signal phase. The inverted DC level signal is input to the + input (non-inverting input terminal) of the comparison circuit 18.

Then, the level of the input audio signal R is compared with the inverted DC level signal by the comparison circuit 18, and a discrimination signal is derived as the comparison output. That is, according to the phase and level of the input audio signal, the output of the comparison circuit 18 has a non-zero output if the audio signal is bilingual audio, and a zero output if the audio signal is stereo monaural audio. can get.

The output of the discrimination signal is a malfunction based on the discrimination of the voice signal of the voice multiplex signal (for example, the voice signal level of one or both of the main voice and the sub-voice of the bilingual voice is temporally reduced to zero level). , Or when the signal phases of the Lch and Rch signals of the stereo sound are temporarily deviated from each other, and the erroneous determination is made, for example, by the waveform shaping circuit 20. The waveform is shaped by disabling the response for a predetermined period and cutting the voltage level of the discrimination signal output of the malfunction period at a predetermined level, and the waveform-shaped switch control signal is output to the switch circuit 9.

The switch circuit 9 is switch-controlled by the switch control signal. In the case of bilingual voice, the switch circuit 9 is switched to the terminal A by a high-level switch control signal to select the main voice, and the stereo voice is selected. In the case of monaural sound, the switch circuit 9 is switched to the terminal B side by a low-level switch control signal to select a mixed sound of Lch and Rch, and a sound signal corresponding to each switch control signal is output from the switch circuit 9. More voice recording circuit 1
0 is supplied.

[0023]

As described above, according to the present invention, in a VTR for recording an AF signal (audio FM signal) on an inclined track and duplicating a magnetic tape on which an audio signal is recorded on a horizontal track provided in a longitudinal direction. , Regardless of the audio signal recorded on the horizontal track, the signal type of the audio multiplex signal is always recorded based on the signal determined by phase inversion and comparison, so that the audio signal recorded on the original magnetic tape When duplicating an original magnetic tape on which different types of audio multiplexed signals are recorded on a single magnetic tape, it is necessary to manually change the tape according to the signal type. Can be eliminated. Moreover, the present invention can be implemented with a simple configuration, and the effect is great.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram for explaining the principle of an embodiment.

FIG. 2 is a circuit block diagram of an embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st input terminal 2 2nd input terminal 8 Mixing circuit 9 Switch circuit 10 Voice recording circuit 12 Phase inversion means 13 Comparison means 14 Reference level 17 Phase inversion circuit 18 Comparison circuit 19 VREF

Claims (1)

(57) [Scope of request for utility model registration] 1. An audio signal recording circuit of a VTR for dubbing an audio multiplex signal recorded at a predetermined recording position on a magnetic tape to another magnetic tape, wherein an Lch (or main) audio, an Rch (or a sub) audio of a reproduced audio signal is provided. First and second input terminals to which respective audio signals are input, and a mixing circuit for mixing Lch (or main) audio and Rch (or sub) audio signals from the first and second input terminals, respectively. Phase inverting means for comparing an audio signal from the first input terminal based on a predetermined reference level and inverting a phase; a signal level generated by the phase inversion means and an audio signal from the second input terminal; Comparing means for deriving a discrimination signal based on the audio multiplex signal by comparing the levels of the audio signal and the audio signal from the mixing circuit and the audio signal from the first input terminal according to the discrimination signal. A VTR, comprising: a switch circuit; and an audio recording circuit that performs signal processing to record an audio signal selectively output from the switch circuit on a horizontal track provided in a longitudinal direction of the magnetic tape. Audio signal recording circuit.