JPS5958605A - Video tape recorder - Google Patents

Abstract

PURPOSE:To resolve the inconvenience of a video tape recorder for after-recording by providing a sum/difference circuit and a main/auxiliary signal leading-out circuit and leading out respective outputs by a switching circuit. CONSTITUTION:In the stereo mode, a sum/difference circuit 11 receives a left signal L and a right signal R from input terminals 1 and 2 and leads out a sum signal L+R from a line 12 to an individual contact 41B and leads out a difference signal L-R from a line 13 to an individual contact 42b. In the sound multiplex mode, a main signal and an auxiliary signal are inputted to terminals 1 and 2 respectvely and they are given to individual contacts 41a and 42a through lines 51 and 52. Signals from common contacts 41c and 42c of switching circuits 41 and 42 are inputted from lines 62 and 63 to amplifying circuits 21 and 22 and are amplified and are given to magnetic heads 31 and 32. Consequently, contacts 41c and 42c of circuits 41 and 42 are connected to the (b) side in the stereo mode and are connected to the (a) side in the sound multiplex mode to record a desired signal on a magnetic tape.

Description

TECHNICAL FIELD The present invention relates to a video tape recorder having two audio tracks for recording and reproducing stereo sound sources and audio multiplex sound sources.

Prior Art In the video tape recorder of the prior art, in stereo mode, the signal sent to the left speaker on the first channel is sent to the second channel.
A method is used in which the signal sent to the right speaker is recorded in the channel. The operation of recording audio after recording is called dubbing. When performing dubbing, for example, the signal recorded on the second channel is erased and the dubbing signal is recorded. At this time, the original sound remains in the first channel, but this sound is the left side component of the stereo, and the sound field of the reproduced sound is unbalanced and becomes unnatural.

Object The object of the present invention is to provide a video tape recorder which overcomes the disadvantages of prior art video tape recorders during dubbing.

Embodiment FIG. 21 shows the configuration of an embodiment of the present invention during recording. When recording a stereo signal, a left signal R and a right signal R of audio frequency are respectively applied to the input terminals 1 and 2.

The change-over switches 41 and 42 change the switching correspondence between stereo and audio multiplexing. In stereo mode, the common contact 41c of the changeover switch 41 and t42
, 42c are electrically connected to the individual contacts 41b, 42b, and the common contacts 41c, 42c are electrically connected to the individual contacts 41a, 42b during audio multiplexing.
Conducts to 2a. The sum-difference circuit 11 receives the left signal R and the right signal R from the input terminal 1.2, derives the sum signal (L+R) l from the line 12 to the individual contact 41b, and outputs the difference signal from the line 13 to the individual contact 42b. (L-R)711-Derived. Main signal and sub signal from input terminals 1 and 2, line 5
1.52 to the individual contact 41at42a. Common contacts 41c and 42 of changeover switches 41 and 42
Signals from c, lines 62, 63. The signal is then applied to recording amplifier circuits 21 and 22 for amplification. During stereo signal recording, the sum signal and difference signal from the sum-difference circuit 11 enter the amplifier circuits 21.22 through lines 62.63, are amplified, and are applied to the magnetic heads 31.32, respectively.

Next, when recording audio multiplexed signals, input terminal 1 and input terminal 2
A main signal and a sub-signal are input to each of these. The main signal here corresponds to the audio signal in a conventional television reception signal, and is the main signal in the case of audio multiplexing, and the sum signal (L+R) in the case of stereo. Further, in the case of audio multiplexing, the subsignal is a subcarrier for an audio signal such as a foreign language, and in the case of stereo, the difference signal (L-R) is frequency-modulated with a subcarrier. Switches 41, 42'i - When switched to the aa side of each individual frame, the main signal is sent to the individual contact 41a of the switch 41, and the sub-item h is sent to the individual contact 42aK of the switch 42.
The number is derived via line 51.52. main signal d,
The sub signal is input to the recording amplifier circuit 21 via the line 62, the sub signal is input to the distribution amplifier circuit 22 via the line 63, and the output signal of the recording amplifier circuit 21.22 is output from the magnetic head: (1, 32 are respectively input to the magnetic head 31.3.
2 converts electrical signals into magnetic signals and records them on a magnetic tape.

Next, FIG. 2 shows the configuration of the audio circuit during playback. When reproducing a stereo sound source, the magnetic heads 31 and 32 input a magnetic signal 1 from a magnetic tape, convert it into an electrical signal, and output it. The outputs of the magnetic heads 31 and 32 each have a sum signal (L+R) and a difference signal (L-R) in stereo, and these signals are sent to the reproduction equalizer amplifier circuit 61.6.
2 increases the SN ratio and sharpens the waveform. Playback equalizer amplification times? The signal coming out from 861.62 (L
10R) and (LR) are respectively input to the sum-difference circuit 11, and the signals R'i are obtained as outputs. The signal is led out from the individual contact 81b of the left signal switch 81 to the common contact 81c, is input to the reproduction amplifier circuit 71 via the line 10, and is amplified by the internal reproduction amplifier circuit 71. Reproduction amplifier circuit 7
The left signal amplified by 1 is led out to the output terminal 3, and is led to the left amplifier circuit, speakers, etc. on the other hand,
The right signal R is led to the individual contact 82b of the switch 820, is input to the reproducing amplifier circuit 72 via the line 111, and is amplified by the reproducing amplifier circuit 71. The amplified right signal R is led to the output terminal 4 and guided to the right amplifier circuit, speaker, etc.

Next, when playing multiple audio sound sources, switch 81°82 connects common contacts 81c and 82e to Okabetsu cup points 81a and 82a.
Give an example. The signals converted into electrical signals by the magnetic heads 31 and 32 become main and sub signals, respectively, and are input to each reproduction equalizer amplification circuit 61 and 62. The main signal output from the output equalizer increase qQ 1011 61 is input to the reproduction amplifier circuit 71 via the line 91 and the line 10 because the switch 81 is switched to the individual contact a side. The main signal amplified by the reproducing amplifier circuit 71 is led to the output terminal 3 and then to the left amplifier circuit, speaker, etc. On the other hand, since the switch 82 is in contact with the individual contact a side, the sub signal which is the output from the endogenous equalizer amplification circuit 62 is transmitted to the line 92. The signal is inputted to the reproduction amplifier circuit 72 via the input signal ll'i. The sub-signal amplified by the reproduction amplifier circuit 72 is led to the output terminal 4 and output to the right 91.
It is guided to i1's amplifier circuit, speaker, etc. Note that a circuit may be added to output the VF main signal or sub signal to both the output terminals 3 and 4 during audio multiplexing.

Next, the circuit configuration during post-recording is shown in FIGS. 3 and 4. Figure 53 shows the circuit configuration during post-recording of a stereo sound source. The signal from the magnetic head 31 of the first channel is transmitted to the reproduction equalizer amplifier circuit 61 and the reproduction amplifier circuit 711F!
: through, output terminal 3 reproduces the sum signal (L+R),
A post-record signal is input to the input terminal 2 of the second channel, and the post-record signal is recorded by the recording amplifier circuit 22. The recording amplifier circuit 22 is configured to erase the previously recorded difference signal (LR) and record a new post-recording signal. The post-recording signal amplified by the recording amplifier circuit 22 is input to the magnetic bed 32, which converts the electrical signal into a magnetic signal and records it on a magnetic tape.

Next, FIG. 4 shows a circuit configuration during post-recording of an audio multiplex sound source. The main signal from the magnetic head 31 of the first channel is amplified by the reproduction equalizer amplifier circuit 61 and the reproduction amplifier circuit 71, and is outputted to the output terminal 3, and guided to the left amplifier circuit and speaker. An after-recording signal is input to the human power terminal 2 of the second channel, and is amplified by the recording amplifier circuit 22, and the amplified after-recording signal is sent to the magnetic head 32.
is input. The recording amplifier circuit 22 erases the previous sub-signal and records a new post-recording signal.

The magnetic head 32 converts the electrical signal into a magnetic signal and records the post-recording signal on a magnetic tape.

In this manner, the illustrated embodiment is effective in dubbing a stereo sound source even in a video tape recorder in which both channels perform bias recording.

In video tape recorders, with the advent of long-time modes, there is a problem of deterioration of frequency characteristics with respect to bias recording audio due to a decrease in tape speed. Therefore, audio frequency modulation recording using a video head has been proposed with the aim of achieving high quality.

However, frequency modulation recording has the disadvantage that dubbing cannot be performed. However, frequency change recording is recording changes in frequency as changes in magnetic frequency, and non-frequency recording is recording changes in voltage or current magnetically using the linear part of the hysteresis curve of a magnetic element. It is to record changes.

As another example, considering that it is difficult for humans to hear, frequency modulation recording has high sound quality, and the difference component of the stereo signal may have a lower quality in both frequency characteristics and dynamic range than the first component. Therefore, the first channel (・ζ
The audio is frequency modulated and recorded, and the second channel is biased. like this. When recording, the first channel is a sum signal (L + R) in stereo due to frequency modulation recording,
The frequency characteristics of the main signal during audio multiplexing are good, and the overall sound quality perceived by human hearing is in the best condition even when the second channel is biased recording. In other words, the sound quality of the original sound source is the best when a stereo sound source is played back as monaural or when a stereo sound source is dubbed, and the sound quality of the main signal sound source is the best both when playing back a multiplexed sound source and after-recording. In standard stereo playback, the difference signal (L-R) is recorded as a bias recording, so the frequency response does not extend sufficiently in the high range, but if the sum signal (L + R) is obtained with sufficient quality, the difference signal (LR) provides a sufficient stereo effect even with low quality.

Effects As described above, the present invention is effective for post-recording of stereo sound sources even in a video tape recorder in which both channels perform bias recording. In addition, the first channel is recorded as FM,
It is even more effective in a video tape recorder that records bias recording on the second channel.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of the audio circuit of the Ichihaya example during recording according to the present invention, Figure 2 is a configuration diagram of the audio circuit of the embodiment during playback according to the present invention, and Figure 3 is a diagram showing the configuration of the audio circuit of the embodiment during playback according to the present invention. FIG. 4 is a circuit diagram showing the circuit configuration during post-recording of an audio multiplex sound source. 11... Sum-difference circuit, 21.22... Recording amplifier circuit, 31.32... Magnetic head, 41, 42, 81, 8
2... Changeover switch, 51.52,91,92.
... line, 61.62 ... reproduction equalizer amplification circuit, 71.72 ... reproduction amplifier circuit, 62, 63. in
. 111... Line, 1, 2... Input terminal, 3, 4...
... Output terminal agent Patent attorney Kei Nishi Part 2 Figure 3 Figure 77 Figure 4

Claims (1)

[Claims] A left and right sum signal in stereo or a main signal in audio multiplexing is recorded in the first channel of the magnetic tape, and a left and right difference signal in stereo or a sub signal in audio multiplexing is recorded in the second channel. a sub-signal derivation circuit that records the sum signal and difference signal into left and right signals during stereo playback, a main sub-signal derivation circuit that individually derives the main signal and sub-signal during audio multiplex playback, and A video tape recorder comprising a switching circuit that switches and derives outputs from a difference circuit and a main/sub signal deriving circuit.