JPH0415547B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic recording and reproducing apparatus that includes a recording system that records audio using the PCM method and a reproducing system that reproduces the recorded audio signal.

(Prior Art) In a conventional magnetic recording/reproducing device that records audio using the PCM method, an ID word is recorded in synchronization with the start and stop of recording of an audio signal.

(Problem to be Solved by the Invention) However, if the ID word is recorded at the start and stop of recording of the audio signal, the audio output will not be possible until the PCM signal is processed during playback and the content of the ID word is determined. It was not possible to switch the switching circuit to a mode (``stereo'', ``bilingual'', ``monaural'', etc.) according to the content of the recorded audio signal. Therefore, there is a problem in that the audio output switching circuit switches at the same time as the audio signal is reproduced by the audio output switching circuit, causing unpleasant noise to be generated from the audio output switching circuit.

(Means for solving the problem) The magnetic recording and reproducing device of the present invention has an audio signal.
A device comprising a recording system that records according to the PCM method and a reproduction system that reproduces the recorded audio signal, the recording system processing the audio signal into a PCM signal and outputting the PCM signal to a recording amplifier. a signal processing circuit, an ID word generation circuit that generates information regarding the audio signal as a certain code and outputs it to the recording system of the PCM signal processing circuit, and a recording start point and recording stop when recording the audio signal; A mute signal that mutes the audio signal for a certain period from each point is output to the PCM signal processing circuit, and the ID word is output from the recording start point to the output stop point of the mute signal output after recording is stopped. and a system control circuit that outputs a control signal instructing generation to the ID word generation circuit, the reproduction system comprising:
a PCM signal processing circuit that processes and outputs the audio signal reproduced from the recording medium; an audio signal switching circuit that switches and outputs the audio signal output from the PCM signal processing circuit; The configuration includes an ID word detection circuit that detects the ID word, and a system control circuit that controls switching of the audio output switching circuit based on the ID word detected by the ID word detection circuit.

(Function) When recording an audio signal, the system control circuit generates a mute signal that mutes the audio signal for a certain period of time at the start and end of recording the audio signal.
Output to PCM signal processing circuit. As a result, in the PCM signal processing circuit, the input audio signal is muted for a certain period of time from the recording start point of the audio signal, and is not written to the memory. Also,
The audio signal is also muted for a certain period of time from the recording stop point of the audio signal.

Furthermore, the system control circuit outputs a control signal instructing generation of an ID word to the ID word generation circuit from the recording start point to the output stop point of the mute signal output after recording is stopped.
This causes the ID word to be written to memory even during the period when the audio signal is muted.

That is, the ID is used for a certain period of time before recording the audio signal.
The ID word is recorded, and the ID word is recorded for a certain period of time even after the recording of the audio signal ends.

On the other hand, when reproducing a recording medium on which such an ID word and audio signal are recorded, the ID word detection circuit detects the reproduced ID word and supplies it to the system control circuit. Based on this ID word, the system control circuit switches the audio output switching circuit according to the information indicated by the ID word (``stereo'', ``bilingual'', ``monaural'', etc.). After this switching, the reproduced audio signal from the PCM signal processing circuit is given to the audio output switching circuit.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

1 and 2 show a schematic configuration of a magnetic recording/reproducing apparatus of the present invention, with FIG. 1 showing a recording system and FIG. 2 showing a reproducing system, respectively.

In the recording system shown in Fig. 1, 1 is an audio input switching circuit, 2 is an A/D (analog/digital) conversion circuit,
3 is a PCM signal processing circuit, 4 is an ID word generation circuit,
5 is a system control circuit, 6 is a recording amplifier, 7a and 7b are audio input terminals, 8 is a recording/reproducing head, and 9 is a magnetic tape.

Further, FIG. 5 shows a more detailed circuit configuration of the PCM signal processing circuit 3, ID word generation circuit 4, and system control circuit 5 shown in FIG.

That is, the PCM signal processing circuit 3 has a conventionally well-known configuration, and includes a gate circuit 31, a changeover switch 32, a memory 33, a memory address generation section 34,
PCM recording control section 35, error correction code generation section 36, and error detection data generation and modulation section 37
It is composed of. The A/D conversion input from the A/D conversion circuit 2 is connected to a contact a of a changeover switch 32 via a gate circuit 31. Further, the output of the ID word generation circuit 4 is led to the contact b of the changeover switch 32, the output of the error correction code generator 36 is led to the contact c, and the movable contact d is connected to the data input D _I of the memory 33. being guided.

Further, the data output D _O of the memory 33 is guided to an error correction code generation section 36 and an error detection data generation and modulation section 37, and is connected to an address input A of the memory 33 and an input R/ for writing and reading.
An address signal and a timing signal from the memory address generation section 34 are respectively guided to W. Further, the output of the PCM recording control section 35 is connected to the memory address generation section 34, the switching control input of the changeover switch 32, and the error correction code generation section 3.
6, an error detection data generation and modulation section 37,
ID word generating section 4.

On the other hand, the recording signal P _O is guided to the control pulse generation section 51 of the system control circuit 5, and the control pulse generation section 51 sends a mute signal P ₁ to the gate circuit 31.
A control signal P ₂ is output to each ID word generating section 4.

In the reproduction system shown in Fig. 2, 10 is a reproduction amplifier, 11 is a PCM signal processing circuit, and 12 is a D/A
(digital/analog) conversion circuit, 13 is an audio output switching circuit, 14 is an ID word detection circuit, 15 is a system control circuit, and 16a, 16b are audio output terminals.

Further, FIG. 6 shows a more detailed circuit configuration of the PCM signal processing circuit 11, ID word detection circuit 14, and system control circuit 15 shown in FIG. 2.

That is, the PCM signal processing circuit 11 has a conventionally well-known configuration, and includes an error detection and demodulation section 111,
Changeover switch 112, memory 113, memory address generation section 114, PCM playback control section 1
15 and an error correction section 116. The reproduction signal from the reproduction amplifier 10 is
It is connected to a contact a of a changeover switch 112 via an error detection and demodulation section 111. Further, the output of the error correction unit 116 is led to the contact b of the changeover switch 112, and the movable contact c is led to the data input D _I of the memory 113.

Further, the data output D _O of the memory 113 is guided to the error correction unit 116, the D/A conversion circuit 12, and the ID word detection circuit 14, and is connected to the address input A of the memory 33 and the input R for writing and reading. An address signal and a timing signal from the memory address generation section 114 are respectively guided to /W. Further, the output of the PCM playback control section 115 is output from the memory address generation section 114.
, an error detection and demodulation section 111 , a switching control input of a changeover switch 112 , and an error correction section 116 .

On the other hand, the output of the ID word detection circuit 14 is guided to the switching signal generating section 151 of the system control circuit 15, and the output of the switching signal generating section 151 is guided to the audio output switching circuit 13. There is.

In the magnetic recording/reproducing apparatus having the above configuration, the operation of the recording system will first be explained with reference to timing charts shown in FIGS. 3 and 4.

The L channel and R channel audio signals inputted from the audio input terminals 7a and 7ba are appropriately switched by the audio input switching circuit 1, and the A/D
After being converted into a digital signal by the conversion circuit 2, it is input to the gate circuit 31 of the PCM signal processing circuit 3. Here, the audio is muted by the mute signal P ₁ (see FIG. 4) generated by the control pulse generator 51 of the system control circuit 5. The audio data passing through the gate circuit 31 is applied to a contact a of a changeover switch 32. At this time, the changeover switch 32
Since it is connected to the movable contact a under the control of the PCM recording control unit 35, the audio data is written into the memory 33 via the changeover switch 32.

Once a certain period of audio data has been written,
The changeover switch 32 is the PCM recording control section 3
5, the connection of movable contact d is made to contact b.
Switch to . At this time, ID word generation circuit 4
Since the ID word is generated by P ₂ from the control pulse generator 51, this ID word is written into the memory 33. Thereafter, the changeover switch 32 switches the connection of the movable contact d to the contact c under control from the PCM recording control section 35. As a result, the data output of the memory 33
After data is read from D _O and a correction code is generated in the error correction code generation section 36, the correction code is recorded in the memory via the changeover switch 32. Thereafter, the data is read from the data output D _O of the memory 33 and sent to the error detection data generation and modulation section 37, where the detection data is added and modulated, and then sent via the recording amplifier 6 and the recording/playback head 8. It is recorded on the magnetic tape 9.

The control pulse generator 51 of the system control circuit 5 generates a mute signal P ₁ which is ON for a certain period of time in synchronization with the rising and falling edges of the recording signal P _O , based on the recording signal P _O indicating the start and stop of recording. , recording signal P _O and mute signal
A control signal _P2 is generated by logical ORing with _P1 . And "H" of this mute signal _P1
Gate circuit 3 only for the level period (for example, 1 second)
The audio mute is applied by 1, and the control signal is
The ID word is output from the ID word generation circuit 4 only during the period when _P2 is at the "H" level. With such timing, a voice mute is played at the timing shown in FIG. 3, and an ID word is recorded.

Next, the operation of the reproducing system of the magnetic recording/reproducing apparatus when reproducing the audio signal and ID word shown in FIG. 3 recorded in this manner will be described.

The reproduction signal reproduced from the magnetic tape 9 and output from the reproduction amplifier 10 is sent to the error detection and demodulation section 1.
After demodulation and error detection are performed in step 11, the signal is applied to contact a of changeover switch 112. At this time, the changeover switch 112 has the movable contact c connected to the contact a under the control of the PCM playback control section 115, so that the playback data is written to the memory 113 via the changeover switch 112. Then, the playback data for a certain period is stored in the memory 11.
3, the changeover switch 112
The movable contact c is switched to the contact b under control from the PCM reproduction control section 115. As a result, data is read from the data output D _O of the memory 113, subjected to error correction processing in the error correction section 116, and then written to the memory 116 via the changeover switch 112. corrected memory 1
The data on the D/A conversion circuit 13 includes audio data and an ID word.
After being converted into an analog audio signal, the ID word is sent to an audio output switching circuit 13, and the ID word is sent to an ID word detection circuit 14.

Then, monaural, stereo, and bilingual detection is performed in the ID word detection circuit 14,
The detection signal is sent to the switching signal generation section 151 of the system control circuit 15, and monaural, stereo, and bilingual switching signals are created.
This switching signal is sent to the audio output switching circuit 13, and audio switching corresponding to monaural, stereo, and bilingual is performed.

In this way, since the audio output switching circuit 13 is switched in accordance with the mode of the recording signal before the audio signal is output, no unpleasant sound (noise) is generated due to switching of the audio output switching circuit 13. Also, at the recording stop point E, the ID word disappears after a certain period of time has elapsed after the audio signal disappears, so that no unpleasant sound (noise) is generated due to switching of the audio output switching circuit 13 in this case as well.

(Effects of the Invention) As explained above, according to the magnetic recording and reproducing apparatus of the present invention, unpleasant noises can be generated during reproduction by shifting the recording timing of an audio signal and an ID word when recording on a magnetic tape. can be prevented from occurring.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram showing the recording system of the magnetic recording and reproducing apparatus of the present invention, FIG. 2 is a schematic block diagram showing the reproducing system of the same apparatus, FIG. 3 is a timing chart of audio signals and ID words, and FIG. The figure shows the input/output timing chart of the control pulse generator.
Figure 5 is a block diagram showing a more detailed circuit configuration of the recording system's PCM signal processing circuit, ID word generation circuit, and system control circuit, and Figure 6 is the reproduction system's PCM signal processing circuit, ID word generation circuit, and system. FIG. 3 is a block diagram showing a more detailed circuit configuration with a control circuit. 1... Audio input switching circuit, 2... A/D conversion circuit, 3, 11... PCM signal processing circuit, 4... ID
Word generation circuit, 5, 15... System control circuit, 6... Recording amplifier, 8... Recording and reproducing head, 9... Magnetic tape, 10... Reproducing amplifier, 1
2...D/A conversion circuit, 13...Audio output switching circuit, 14...ID word detection circuit.

Claims (1)

[Scope of Claims] 1. An apparatus comprising a recording system that records an audio signal using the PCM method and a reproduction system that reproduces the recorded audio signal, wherein the recording system converts the audio signal into a PCM signal. a PCM signal processing circuit that processes the audio signal and outputs it to a recording amplifier; an ID word generation circuit that generates information about the audio signal as a certain code and outputs it to the recording system of the PCM signal processing circuit; At the time of recording, a mute signal that mutes the audio signal for a certain period of time from the recording start point and recording stop point is output to the PCM signal processing circuit, and the mute signal that is output from the recording start point after recording is stopped is output to the PCM signal processing circuit. and a system control circuit that outputs a control signal instructing the generation of the ID word to the ID word generation circuit until an output stop point, and the reproduction system processes the audio signal reproduced from the recording medium. and a PCM signal processing circuit that outputs the
An audio output switching circuit that switches and outputs the audio signal output from this PCM signal processing circuit, an ID word detection circuit that detects the ID word reproduced from the recording medium, and detection by this ID word detection circuit. and a system control circuit that controls switching of the audio output switching circuit based on the ID word.