JP3048159B2 - Audio signal playback device - Google Patents

Description

The present invention relates to an audio signal reproducing apparatus, and more particularly to an audio signal reproducing apparatus capable of reproducing an audio signal of two channels.

2. Description of the Related Art Conventionally, there is known a video tape recorder (VTR) that performs frequency multiplexing of a monaural audio signal FM-modulated to a video signal and records and reproduces the same. In this type of equipment,
Recently, FM for monaural audio signals has been used
An apparatus has been disclosed in which a second FM modulated carrier is prepared in addition to the modulated carrier, and a stereo audio signal is recorded and reproduced using the second FM modulated carrier. That is, the conventional monaural audio signal is the left (L) and right (R) of the stereo audio signal.
Of the stereo audio signal by the second carrier using the difference signal (L−R) of the stereo audio signal.
R) is FM-modulated and recorded.

If a conventional monaural audio signal is used as the main audio signal and the sub audio signal is recorded using the second carrier, the main and sub audio signals such as bilingual audio can be recorded in the same manner.

Considering that a stereo audio signal or a main / sub audio signal is reproduced as described above, a conventional carrier audio signal (hereinafter simply referred to as a first audio signal) is a sum signal of a stereo audio signal or a main audio signal. A signal is recorded, and as a sound signal by the second carrier (hereinafter simply referred to as a second sound signal), a difference signal of a stereo sound signal or a sub sound signal is recorded. Therefore, when outputting a stereo audio signal, the first and second audio signals must be supplied to a matrix circuit, and the left and right audio signals must be output from the matrix circuit. Requires that the first and second audio signals be output as main and sub audio signals as they are.

Manually switching the output as described above increases the complexity and confusion. In addition, if the switching is performed incorrectly, the reproduced sound quality is significantly impaired. Therefore, it is desirable that the above output switching be performed automatically. In such automatic switching of output, identification information for identifying the type of audio signal is recorded in a recording medium in some form,
This can be realized by performing the above switching according to the identification information.

[Problems to be Solved by the Invention] However, when dubbing an audio signal in such a VTR, the following problems are induced.

First, when a sum / difference signal of a stereo audio signal is recorded on the reproduction side VTR, the signal is temporarily converted into left and right signals by a matrix circuit and output, and the left and right signals are again summed and difference signals by the matrix circuit. To be recorded.
As described above, when dubbing is performed twice through the matrix circuit, the S / N ratio is deteriorated and the left and right signals are incompletely separated, which is not preferable.

In consideration of reproducing a dubbed audio signal, it is necessary to record identification information for identifying whether the audio signal recorded by dubbing is a stereo audio signal or a main / sub audio signal. That is, it is necessary for the operator to always recognize the type of the audio signal being dubbed, switch the switch, etc., and record the identification information. The operation of recording the identification information at the time of dubbing is very troublesome for the operator.

Further, when the audio signal to be dubbed is a monaural signal, it is desirable not to record the second audio signal. This is because the FM modulated signal of the second audio signal leaks into the first audio signal or leaks into the video signal band. That is, this leakage (crosstalk) adversely affects other signals. However, also in this case, the operator always recognizes whether or not the audio signal being dubbed is a monaural audio signal, and determines whether or not to record the second audio signal by switching a switch or the like. There must be.

[Means for Solving the Problems] Under the background described above, according to the present invention, dubbing is performed by outputting a reproduced audio signal to a recording device and recording the audio signal in the recording device. A playback device used in a system for performing, from a recording medium, playback of an audio signal indicating stereo audio or main / sub audio and an identification signal for identifying whether the audio signal is stereo audio or main / sub audio. Means, a detecting means for detecting an identification signal reproduced by the reproducing means, and at the time of dubbing the audio signal reproduced by the reproducing means, when dubbing the audio signal reproduced by the reproducing means and the detection result of the detecting means. And a means for outputting the information based on the information to the recording device.

EXAMPLES Hereinafter, the present invention will be described with reference to examples.

FIG. 1 shows a reproduction system P of a VTR as an embodiment of the present invention.
And a configuration of a recording system R of a VTR that records a reproduction signal from the reproduction system during dubbing.

Here, the frequency allocation of the signal recorded on the magnetic tape 1 will be briefly described with reference to FIG. In FIG. 2, P indicates a pilot signal for performing a known four-frequency tracking control, C indicates a low-frequency converted chroma signal, and Y indicates a recording band of an FM-modulated luminance signal. A1 is a first audio signal modulated by FM, A2
Indicates a recording band of the second audio signal modulated by FM. The frequency of the FM modulated carrier of this first audio signal is 1.5M
Hz, and the frequency of the FM modulated carrier of the second audio signal is 1.
7 MHz.

Hereinafter, the operation of the reproduction system shown in FIG. 1 will be described step by step.

The signal recorded on the magnetic tape 1 is reproduced by the magnetic head 2 and then amplified by the reproduction amplifier 3 to a predetermined level. The video signal in the reproduced signal is subjected to well-known processing in a video signal reproduction processing circuit 4 and output from a video output terminal 5 in the form of a television signal. First FM extracted by a band-pass filter (BPF) 6 from the reproduced signal
The modulated audio signal is supplied to the first audio signal reproduction processing circuit 7, where the sum signal (L + R) signal or the main audio signal is restored. On the other hand, the second FM modulated audio signal extracted by the BPF 12 is supplied to the second audio signal reproduction processing circuit 13, where the difference signal (L
-R) or the secondary audio signal is restored.

Reference numeral 8 denotes a matrix circuit for converting the sum signal (L + R) and the difference signal (LR) from the processing circuits 7 and 13 into a left signal L and a right signal R. The analog switch circuit 9 is a circuit for selecting whether or not to output the reproduced first and second audio signals through a matrix circuit. In the present embodiment, the control terminal of the analog switch circuit 9 has a logical high level (" H ”), the logic is such that a signal that does not pass through the matrix circuit 8, that is, a signal output from the circuits 7, 13 is output as it is.

The monaural detection circuit 14 outputs "H" when the carrier of the second audio signal does not exist. In addition, the identification signal detection circuit 15
Outputs “H” when it is detected from the identification signal described later that the main and sub audio signals are recorded. The gate 17 is a circuit for controlling the analog switch circuit 9 except for dubbing described later. That is, the outputs of the OR gate 17 and the OR gate 18 become "H" when the carrier of the second audio signal does not exist, or when the main and sub audio signals are recorded, and the output of the processing circuits 7 and 13 is the first output. , Second
Is output from the output terminals 10 and 11 as they are. On the other hand, when the recorded signal is a stereo audio signal, the output of the AND gate 17 becomes a logical low level ("L"), and the OR gate 17 is not used except when dubbing.
Since the output of 18 also becomes “L”, the left and right audio signals output by the matrix circuit 8 are output from the terminals 10 and 11.

During dubbing, the video output terminal 5 is connected to the video input terminal 51 of the recording system R, and the audio output terminals 10 and 11 are connected to the audio input terminals 52 and 53. The dubbing control terminal 19 is connected to the dubbing control terminal 54, and the monaural detection information output terminal 20 is connected.
Is connected to the detection information input terminal 55, and the identification information output terminal 21 is connected to the identification information input terminal.

In the recording system R , the video signal input to the terminal 51 is subjected to well-known processing by a video signal recording processing circuit 57,
Is mixed with the FM modulated audio signal by the mixer 75, the current is made constant by the recording amplifier 66, and is recorded on the magnetic tape 68 by the magnetic head 67.

In the recording system R , reference numeral 69 denotes an operation switch for instructing dubbing, and reference numeral 70 denotes an operation switch for instructing whether an input audio signal other than during dubbing is a stereo audio signal or a main / sub audio signal.

When the user instructs dubbing by turning on the switch 69, the output of the OR gate 71 becomes "H". Since the terminal 54 of the recording system R and the terminal 19 of the reproducing system P are connected, the output of the OR gate 18 also becomes "H". Therefore, both the switch circuit 9 and the switch circuit 59 output signals that do not pass through the matrix circuits 8 and 58, and processing is performed regardless of whether the audio signal to be dubbed is a main / sub audio signal or a stereo audio signal. The first and second audio signals output from the circuits 7 and 13 are directly input to the processing circuits 60 and 61. That is, when the audio signal to be dubbed is a stereo audio signal, the sum signal (L + R) and the difference signal (LR) are input / output as they are.

The first audio signal recording processing circuit 60 and the second audio signal recording processing circuit 61 perform processing such as FM modulation on 1.5 MHz and 1.7 MHz carrier waves on the first and second audio signals and output the processed signals. The output of the inverter 63 is "H" and the switch 65 is turned on except when it is detected that the second carrier does not exist in the reproduction system P , and the two-channel FM modulation output from the circuits 60 and 61 is performed. The waves are frequency multiplexed in a mixing circuit 72. Also, the playback system P
In the case where the second carrier exists and the main and sub audio signals are reproduced, the outputs of the detection circuits 14 and 15 are “L”,
"H", and becomes "H" of the output of the AND gate 64,
The identification signal recording circuit 62 further mixes the output of the mixing circuit 72 with the identification signal. That is, the identification signals are mixed only when the main and sub audio signals are recorded.

The output of the identification signal recording circuit 62 is mixed with the video signal by the mixer 75. When the second carrier is not detected in the reproduction system P , that is, when the output of the monaural detection circuit 14 is “H”, the output of the second audio signal recording processing circuit 61 is meaningless. When the output becomes "L", the switch 65 is turned off, and the recording of the second audio signal is prohibited. When the output of the inverter 63 is "L", the video signal recording processing circuit 57 expands the exclusive band of the FM modulation luminance signal by the amount of the second audio signal (the band indicated by the dotted line in FIG. 2). ).
Thereby, the resolution of the luminance signal is improved accordingly.

By performing dubbing as described above, the operator can perform appropriate processing in accordance with the type of the reproduced audio signal even if any audio signal is reproduced simply by connecting the reproduction system P and the recording system R. That is, at the time of dubbing, the stereo audio signal is sent from the reproduction system to the recording system in the state of a sum / difference signal, so that dubbing can be performed without passing through a matrix circuit. Incomplete separation can be prevented.

When the main and sub audio signals are dubbed, the reproduction system P automatically detects that the audio signal to be dubbed is the main and sub audio signals, and outputs the detection result as identification information. Using the identification information, the recording system R can record an identification signal indicating that the recording signal is a main / sub audio signal. Therefore, the audio signal recorded by dubbing can be automatically reproduced without bothering the operator.

Further, when dubbing only the audio signal of one channel, the reproduction system P automatically detects this and outputs the detection result, so that the recording system prohibits recording of an unnecessary second audio signal. As a result, it was possible to suppress the adverse effects on the first audio signal and the video signal without bothering the operator. Further, since the bandwidth of the video signal could be widened in the recording system R , the resolution of the video signal could be made as high as possible.

Lastly, a brief description will be given of the operation in the case where normal recording other than dubbing is performed in the recording system R of the VTR in FIG. In this case, since the switch 69 is turned off, the output of the OR gate 71 becomes "H" when the switch 70 is on and "L" when it is off. That is, when the user turns on the switch 70 when recording the main and sub audio signals, the switch 59 inputs the main and sub audio signals input to the terminals 52 and 53 to the recording processing circuits 60 and 61 as they are. Further, the output of the OR gate 71 becomes "H", and the above-described identification signal is recorded.

Although the dubbing command switch 69 is provided on the recording side R in the above-described embodiment, the same operation can be performed by providing the dubbing command switch 69 on the reproducing side P and supplying it to the OR gate 71 via the terminals 19 and 54. Also,
By connecting the recording side R and the reproducing side P , the outputs of the OR gates 18 and 71 are automatically set to "H", so that the load on the operator can be further reduced.

[Effects of the Invention] As described above, according to the present invention, it is possible to obtain an audio signal reproducing apparatus that can reduce the load on the operator when performing dubbing.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a reproducing system of a VTR as one embodiment of the present invention and a configuration of a recording system of a VTR connected to the reproducing system at the time of dubbing, and FIG. FIG. 3 is a diagram for explaining frequency allocation of recorded signals. In the figure, 1 is a magnetic tape as a recording medium, 2 is a reproducing head, 6 and 12 are bandpass filters, 7 is a first audio signal reproduction processing circuit, 8 is a matrix circuit, 9 is a switching circuit, and 10 and 11 are An audio output terminal, 13 is a second audio signal reproduction processing circuit, 14 is a monaural detection circuit, 15 is an identification signal detection circuit, 20 and 21 are output terminals, and 69 is a dubbing command switch.

Claims (3)

(57) [Claims] 1. A reproduced audio signal is output to a recording device,
A playback device used in a system that performs dubbing by recording the audio signal in the recording device, wherein an audio signal indicating stereo audio or main / sub audio, and whether the audio signal is stereo audio or main / sub audio. Reproducing means for reproducing an identification signal for identification from a recording medium; detecting means for detecting the identification signal reproduced by the reproducing means; and dubbing the audio signal reproduced by the reproducing means. Means for outputting, to a recording device, an audio signal reproduced by the method and information based on the detection result of the detection means. 2. An audio signal reproduced from the recording medium,
A patent comprising a first audio signal comprising a left / right sum signal or a main audio signal of a stereo audio signal, and a second audio signal comprising a left / right difference signal or a sub audio signal of the stereo audio signal. The audio signal reproducing device according to claim (1). 3. The apparatus is supplied with the first and second audio signals reproduced by the reproduction means, performs predetermined matrix processing on the first and second audio signals, and outputs them as two-channel audio signals. And a selection unit for selectively outputting the two-channel audio signal output from the matrix circuit according to the identification signal reproduced by the reproduction unit, and the first and second audio signals. The audio signal reproducing apparatus according to claim 2, wherein: