JP2752478B2 - Magnetic recording / reproducing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording and reproducing apparatus for recording information such as video and audio on a magnetic tape or the like by a helical scan method.

[Conventional technology]

FIG. 7 is a diagram showing a magnetic head arrangement and a tape recording pattern in a conventional magnetic recording / reproducing apparatus disclosed in, for example, JP-A-61-165801. In FIG. The drums, 2a and 2b, are a set of first magnetic heads that are 180 degrees apart from each other, 3a, 3b are 180 degrees apart from each other, and are 90 degrees apart from the first magnetic heads 2a, 2b. A set of second magnetic heads at intervals. 4B, reference numeral 4 denotes a magnetic tape, 5 denotes a track 1-A recorded by the first magnetic head 2a, 6 denotes a track 2-A recorded by the second magnetic head 3a, and 7 denotes a first track. Magnetic head
Tracks 1-B and 8 recorded by 2b are tracks 2-B recorded by the second magnetic head 3b.

FIG. 8 is a block diagram showing a recording signal processing system in the case where two-channel video signals are simultaneously digitally recorded with the magnetic head arrangement and the track pattern as shown in FIG. 7, and 9a shows a first channel recording video signal, 9b is a low-pass filter 1 for limiting the band for sampling the second channel recording video signal and 10a for sampling the first channel recording video signal.
(Hereinafter referred to as LPF1), 10b is an LPF2 for limiting the band of the second channel recording video signal, 11a is an A / D converter 1 for sampling the first channel recording video signal, and 11b is a second channel recording. A / D converters 2 and 12a that sample video signals
The encoders 1 and 12b for adding an error correction code or the like to the digital data from the A / D converter 1-11a and encoding the digital data include an A / D converter 2
Encoders 2 and 1 for encoding digital data from -11b
3a is a memory 1 used for encoding in the encoder 1-12a, 13b is a memory 2 used for encoding in the encoder 2-12b, and 1 is a magnetic recording medium for digital data encoded by the encoder 1-12a. A modulator 14b performs recording and encoding optimal for reproduction. A modulator 2b records and encodes digital data encoded by the encoder 2-12b. A modulator 15a outputs an output of the modulator 1-14a to the first magnetic head. Recording head amplifiers 1 and 1 that drive to 2a and 2b
Reference numeral 5b denotes a recording head amplifier 2 for driving the output of the modulator 2-14b to the second magnetic heads 3a and 3b.

FIG. 9 is a diagram showing the distribution of magnetic heads of the first and second channel recording data and the recording period of the magnetic head;
Each channel data is transmitted to a modulator 1-14a and a modulator 2-14b.
The output data of FIG.

 Next, the operation will be described.

In the conventional magnetic recording / reproducing apparatus, as shown in FIG. 7 (a), two sets of magnetic heads are arranged at 180 degrees from each other on the rotating drum 1, and the magnetic tape 4 runs at a normal double speed. Thus, video signals can be recorded and reproduced by the first magnetic heads 2a and 2b, and audio signals or other video signals can be recorded and reproduced by the second magnetic heads 3a and 3b. in this case,
The track 1-A-5 is recorded on the magnetic tape 4 by one of the first magnetic heads 2a as shown in FIG. 4 (b). Track 2-A-6 is recorded by one of the heads 3a. Similarly, the other 2 of the first and second magnetic heads
1-B-7 and 2-B-8 are recorded by b and 3b. Therefore, two pieces of information are recorded by one rotation of the rotating drum 1. Here, the operation of the recording signal processing system will be described by taking as an example the case where two-channel video signals are simultaneously digitally recorded. Although the audio signal processing system is not shown here, it is assumed that the audio signal is digitally recorded in the same manner as the video signal.

As shown in FIG. 8, the first and second channel recording video signals
9a, 9b limit the band so that the video signal band is passed by LPF1-10a and LPF2-10b, and A / D converters 1-11a and A / D
The sampling is performed by the D converter 2-11b at twice or more of the video signal band. Generally, taking the NTSC system as an example, the video signal bandwidth is 4.
It is 5 MHz, and it is necessary to sample at a frequency of 9 MHz or more in view of Nyquist's theorem. Also, since the chrominance signal is transmitted with a quadrature two-phase modulation on a 3.58 MHz carrier, it is usual to set the sampling frequency to an integral multiple of 3.58 MHz in consideration of beat interference with the sampling frequency. It is. From these relations, the sampling frequency is 3 · fsc (fsc means a carrier frequency of 3.58 MHz, and 3 · fsc is about 10.7 MHz) or 4
・ It is often set to fsc (about 14.3MHz). The digitized recorded video data is encoded by an encoder 1-12a and an encoder 2-12b so that errors occurring during magnetic recording and reproduction can be corrected. The encoding here is performed using the memory 1-13a and the memory 2-13b. The coded digital data is further recorded and coded by a modulator 1-14b and a modulator 2-14b so as to be optimal data for magnetic recording and reproduction. For example, NRZ, NRZI
And so on. The modulated recording video data is recorded on the first channel digital data by the first magnetic heads 2a and 2b via the recording head amplifier 1-15a and the recording head amplifier 2-15b, and the second channel digital data is recorded on the first magnetic head 2a. Recording is performed by the second magnetic heads 3a and 3b. Where 2
As shown in FIG. 9, the magnetic head distribution of the recording data of the channel is such that the data 1-1 of the first channel is the first magnetic head 2.
a is recorded on track 1-A-5, and DATA1-2 of the first channel is recorded on track 1-B- by the first magnetic head 2b.
7 is recorded. Similarly, for the second channel, DATA2-1 is recorded on track 2-A-6 by the second magnetic head 3a.
DATA2-2 is track 2-B-8 by the second magnetic head 3b.
Is recorded to With the above operation, video signals of two channels can be simultaneously recorded, and at the time of reproduction, reproduction can be performed by tracing tracks in the same manner.

[Problems to be solved by the invention]

Since the conventional magnetic recording / reproducing apparatus is configured as described above, it is necessary to add two magnetic heads for recording / reproducing a two-channel video signal and to provide a signal processing circuit for two channels. In addition, when the recording and reproduction are partially performed in combination with the recording and reproduction of the video signal of one channel, an empty track is generated in the recording part of one channel, and the recording efficiency is not good.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has been made to achieve one-channel video signal recording / reproduction and two-channel video signal recording / reproduction without adding a magnetic head and without significantly increasing the circuit scale. It is an object of the present invention to obtain a magnetic recording / reproducing device which can be used together and can record efficiently.

[Means for solving the problem]

A magnetic recording / reproducing apparatus according to the present invention comprises: two pairs of magnetic heads for recording / reproducing information on first and second channels each comprising a video signal or an audio signal on a magnetic tape; and the two pairs of magnetic heads. And one rotating drum that traces the magnetic tape and scans N tracks (where N ≧ 1) during one cycle of the information, and the information of the first and second channels is the same. In a magnetic recording / reproducing apparatus of a helical scan type capable of simultaneously recording / reproducing on a magnetic tape, a pair of the magnetic heads mounted on the rotating drum are used, and 2 ×
A drum rotation driving means for driving the rotation drum so as to scan at least N tracks; and a method for simultaneously recording and reproducing the information of the first and second channels, the one of the first and second channels. 2 when recording and reproducing information
A tape running means for running the magnetic tape so that the speed is doubled; and when recording the information of the first and second channels simultaneously, the information of the two channels is written in the first and second channels.
When recording the information of one of the second channels, one time compression means for time-compressing the information of the one channel, and at the time of recording, the signal time-compressed by the time compression means is subjected to signal processing. One recording signal processing means for outputting to the pair of magnetic heads, one reproduction signal processing means for performing signal processing on information output from the pair of magnetic heads during reproduction, and the reproduction signal processing When the time-compressed information of the first and second channels output from the means is simultaneously reproduced, the information of the two channels is time-expanded, and the time-compressed information of the first or second channel is used. When reproducing the information of one of the channels, one time extending means for extending the information of one channel in time is provided.

[Action]

According to the magnetic recording / reproducing apparatus of the present invention, the number of times of scanning of the magnetic head on the magnetic tape (the number of tracks) is increased by rotating the rotating drum twice or more within one cycle of information, and the 1-channel and 2-channel recording / reproducing. The scanning pitch of the magnetic head is changed by switching the running speed of the magnetic tape according to.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numerals 1, 2a, 3b, 4, 9a to 15 are the same as those of the prior art, and 16 is a first and second channel recording video signal 9a and 9b.
A time compression circuit for compressing the time axis of the digitized data for each block; 17 an ID generation circuit for generating an identification data (hereinafter referred to as ID) signal for recording on one track separately from the video data; Is a head selector switch for switching head signals, 19 is a reproducing head amplifier, 20 is a modulator
A demodulator that reproduces and demodulates the data modulated by 14, 21 is an ID detection circuit that separates the ID signal from the reproduced video signal data, and 22 is a decoder that decodes data that has been encoded by the encoder 12 such as error correction at the time of reproduction. , A decoder that performs error correction and detection, 23 is a decoder
The memories 3 and 24 used for decoding at 22 are time expansion circuits for expanding the decoded data on a time axis basis for each block at the same ratio as the time axis compression at the time compression circuit 16, and 25a is a first reproduced video signal. D / A converters 1 and 25b that convert data into analog are second
The D / A converters 2 and 26a for converting the channel reproduced video signal data into analog signals are LPFs 3 and 26b for limiting the bandwidth of the video signals analogized by the D / A converter 1-25a, and the D / A converters 2-25.
LPF that limits the band of the video signal analogized by b
4, 27a are the first channel reproduced video signal, 27b is the second channel reproduced video signal, 28 is a mechanical control circuit for controlling tape running speed, etc., 29 is a recording / reproducing mode switching signal, and 30 is detected by an ID detection circuit. A signal processing switching signal for switching the signal processing system by the ID signal, and a mechanism switching signal 31 for switching the magnetic tape running speed by the detected ID signal.

FIG. 2 (a) shows a track pattern in the one-channel recording / reproducing mode in the above-described embodiment. Reference numeral 31 denotes a track recorded by the magnetic head 2a during the first rotation of the rotary drum 1, 32
Is a track scanned by the magnetic head 2b, and 33 is a rotating drum 1.
The track recorded by the magnetic head 2a in the second rotation is the track scanned by the magnetic head 2b. FIG. 2B shows a track pattern in the two-channel recording / reproducing mode.

FIG. 3 shows the state in the middle of the one-channel recording / reproduction mode operation.
It is a figure which shows the track pattern and tape running speed change of the switching part at the time of switching to a channel recording / reproducing mode, 32 is a track immediately before running speed switching, and 33 is a track recorded / reproduced during a running speed switching period.

FIG. 4 shows the operation in the middle of the one-channel recording / reproduction mode operation.
FIG. 5 is a diagram showing timings when switching to a channel recording / reproducing mode, in which D indicates a magnetic head scanning period (hatched portion) of the magnetic heads 2a and 2b, E indicates channel data to be recorded and reproduced, and F indicates recording. ID signal to be detected, G
Is a recording / reproducing mode switching signal (Low: 1 channel recording / reproducing mode, High: 2 channel recording / reproducing mode), H is a traveling speed switching signal (Low: 1x speed, High: 2x speed), I is a magnetic tape traveling speed, J Is a traveling speed switching completion signal, and K is a signal processing system switching signal (Low: 1 channel recording / reproducing, High: 2 channel recording / reproducing).

FIG. 5 is a diagram showing the change of the track pattern and the tape running speed at the switching portion when switching to the one-channel recording / reproducing mode from the middle of the two-channel recording / reproducing mode operation as in FIG.

FIG. 6 is a diagram showing the respective timings when switching to the one-channel recording / reproduction mode during the operation of the two-channel recording / reproduction mode as in FIG.

 Next, the operation will be described.

In FIG. 1, a set of magnetic heads 2a and 2b spaced 180 degrees is attached to a rotating drum 1, and the rotating drum 1 is rotated twice as much as the conventional one. Accordingly, the scanning of the magnetic head on the magnetic tape 4 is performed as shown in FIG.
By rotating twice in the time required for one rotation of the conventional rotary drum (within one frame period), the magnetic head is used in the first rotation.
The track 31 is scanned by 2a, and the track 32 is scanned by the magnetic head 2b. In the next one rotation, track 33 with magnetic head 2a
And the track 34 is scanned by the magnetic head 2b. In ordinary recording only on the first channel, recording is performed only by the magnetic head 1a in the above track scanning.

Here, a one-channel recording / reproducing mode in which recording / reproducing of only the first channel is performed will be described. As in the prior art, the first channel recording video signal 9a is band-limited by the LPF 1-10a and digitized by the A / D converter 1-11a. This data is made into blocks in field units, for example, and the time compression circuit 16 compresses the time axis to 1/2 or less for each block. The time-compressed data for each block is encoded by the encoder 12 using the memory 1-13, combined with the ID signal from the ID generation circuit 17, and recorded and encoded by the modulator 14 in the same manner as in the prior art. . The recording data here is intermittent data for each one-field period, and is transmitted via the recording head amplifier 15 to the track 31 in FIG.
And the track 33. Therefore, recording is performed only during the scanning period of the magnetic head 2a, and recording is not performed during the scanning period of the magnetic head 2b. Also, at the time of reproduction, data reproduced during the scanning period of the magnetic head 2a is recorded and decoded by the demodulator 20 via the reproduction head amplifier 19. Here it was synthesized at the time of recording
The ID signal and the reproduced video signal data are separated by the ID detection circuit 21,
The reproduced video data is subjected to error correction and error detection / correction by the decoder 22 using the memory 3-23. Next, at the time of recording, the time axis is expanded by the time expansion circuit 24 at the same ratio that the time axis is compressed by the time compression circuit 16 during recording. Here, it is a continuous playback video data sequence for each block, and this data is
It is converted into an analog signal by the D / A converter 1-25a, and the LPF-27a
The first-channel reproduced video signal can be obtained by performing the band limitation.

Next, a two-channel recording / reproducing mode for simultaneously recording and reproducing the first and second channels will be described. In this mode, the feed speed of the magnetic tape 4 is set to double speed. Accordingly, the magnetic head scan on the magnetic tape 4 scans four tracks as in the case of one-channel recording / reproducing as shown in FIG. 2 (b), but the tracks do not overlap and the magnetic head 2a during recording.
4b are recorded in one frame period by 2b and 2b. In the signal processing system, the first and second channel recording video signals 9a, 9
b is LPF1-10a, LPF as in 1 channel recording / playback mode.
The band is limited by 2-10b, digitized by the A / D converter 1-11a and A / D converter 2-11b, and time-compressed by the time compression circuit 16. Here, the time compression is performed for each of the two channels by block, and the compressed data for the two channels is alternately arranged in block units to form a continuous data sequence, and these data are subjected to error correction encoding by the encoder 12, After synthesizing the ID signal, the recording and encoding are performed by the modulator 14 and the first channel recording data is recorded on the magnetic tape 4 by the magnetic head 2a and the second channel recording data is recorded by the magnetic head 2b. At the time of reproduction, the data of each channel is reproduced by the magnetic heads 2a and 2b, recording / decoding by the demodulator 20 and ID detection, error correction / interpolation are performed in the same manner as in the one-channel reproduction mode. The reproduction data for the channels is separated into blocks, and the time axis is extended for each block, thereby obtaining the reproduction video data of the first and second channels. These reproduced video data are converted into analog signals by the D / A converter 1-25a and the D / A converter 2-25b, respectively.
The band is limited by the PF3-26a and the LPF4-26b to obtain the first channel reproduced video signal 27a and the second channel reproduced video signal 27b.

As described above, in the one-channel recording / reproducing mode, the signal processing from time processing after time compression during recording to time decompression during reproduction is intermittent processing of compressed data for one channel, and in the two-channel recording / reproducing mode. This is a continuous process of compressed data for two channels. ID generation circuit 17
In this example, data for distinguishing these two types of recording and reproduction modes is also included, and is recorded on the magnetic tape 4 as an ID signal at the time of recording in each mode. Here, the ID signal in the one-channel recording / reproduction mode is, for example, A,
In the two-channel recording / reproducing mode, B is recorded at two positions on both ends of the track.

Next, a case in which the mode is switched to the other mode during the operation of one of the recording and reproducing modes will be described. First,
When switching from the middle of the one-channel recording / reproducing mode to the two-channel recording / reproducing mode, when the recording / reproducing mode switching signal 29 is received during the one-channel recording operation during recording, the mechanical control circuit 28 changes the magnetic tape traveling from 1 × speed to 2 × speed. Switch to However, since the speed cannot be increased immediately, it is detected that the speed has been increased to double speed, and the signal processing circuit is set to the two-channel recording mode. The recording track pattern on the magnetic tape 4 during the mode switching period is the third
As shown in the figure, some running speed switching periods occur,
During this period, tracks at equal intervals cannot be recorded. Therefore, in order to distinguish it from a normal track,
As the ID signal, an ID signal different from those of the two modes is recorded (here, the ID signal recorded during the traveling speed switching period is C).
In addition, C is also recorded in the ID signal at the end of the track 32 immediately before the switching of the traveling speed so that the traveling speed switching period can be reliably detected.

The above operation will be described with reference to FIG. 4. When the recording mode switching signal 29 is received, the ID signal on the trailing end of the track to be recorded by the next scanning of the magnetic head 2a is recorded, and the magnetic head 2a
The switching of the tape running speed is started at the timing of switching from the magnetic head 2b to the magnetic head 2b, and after detecting that the tape speed has become double, the signal processing system is set to the two-channel recording mode at the timing of switching from the magnetic head 2b to the magnetic head 2a. At the time of reproducing, the recording / reproducing mode switching signal 29 is received during the one-channel reproducing operation, or the change of the ID signal from A to C is detected, and the magnetic tape feed speed and the signal processing system are switched at the same timing as at the time of recording. Let it be the two-channel playback mode.

When switching from the middle of the two-channel recording / reproducing mode to the one-channel recording / reproducing mode, upon receiving the recording / reproducing mode switching signal 29 during recording, the mechanical control circuit
Reference numeral 28 switches the running of the magnetic tape from double speed to normal speed. The signal processing system is simultaneously switched from the two-channel recording mode to the one-channel recording mode, and the recording track pattern is as shown in FIG. In the ID signal recording here, C is also recorded in the ID signal on the trailing side of the track 33 and the track 32 immediately before the switching of the traveling speed during the traveling speed switching period.

The above operation will be described with reference to FIG. 6. When the recording mode switching signal 29 is received, the ID signal on the trailing end of the track to be recorded by the next scanning of the magnetic head 2a is recorded.
The switching of the tape running speed is started at the switching timing from 2a to the magnetic head 2b, and at the same time, the signal processing system is set to the one-channel recording mode.

During recording, the recording / reproducing mode switching signal 29 is received during the 2-channel reproducing operation, or the change of the ID signal from B to C is detected, and the magnetic tape feed speed and the signal processing system are switched at the same timing as during recording. To set 1-channel playback mode.

Although the ID signal is recorded on the helical track in the above embodiment, a linear track may be provided to record and detect the ID signal.

Further, in the above embodiment, the case where one cycle of information is one frame and recording is performed on two tracks per one cycle of information is described. However, one cycle of information may be one field, and may be an integral multiple of one field and one frame. There may be. Further, the number of tracks to be recorded / reproduced per information cycle may be any number.

〔The invention's effect〕

As described above, according to the magnetic recording and reproducing apparatus of the present invention, each of the video signal and the audio signal
Two pairs of magnetic heads for recording and reproducing information of the first and second channels on a magnetic tape, and the two pairs of magnetic heads are mounted.
A helical scan type magnetic recording / reproducing apparatus including one rotating drum for scanning N tracks (where N ≧ 1) during a cycle period, and capable of simultaneously recording and reproducing information of the first and second channels on the same magnetic tape A drum rotation driving means for rotating the rotation drum so as to scan 2 × N tracks or more during one cycle of the information, wherein the magnetic head mounted on the rotation drum is a pair; When simultaneously recording and reproducing the information of the second channel, a tape running for running the magnetic tape at twice the speed of recording and reproducing the information of one of the first and second channels. Means, said first and second
When recording the information of one channel simultaneously, the information of the two channels is used. When recording the information of one of the first and second channels, one time for compressing the information of the one channel is used. Compression means, one recording signal processing means for signal-processing the information time-compressed by the time compression means at the time of recording, and outputting the processed information to the pair of magnetic heads; One reproduction signal processing means for performing signal processing on the output information, and 2 when simultaneously reproducing the time-compressed information of the first and second channels output from the reproduction signal processing means. When one of the first and second information that has been time-compressed is reproduced by time-expanding the information for one channel, one time-expansion means for time-expanding the information for one channel is provided. Because, one channel or two
There is an effect that the channel recording / reproduction can be switched even while the magnetic tape is running.

[Brief description of the drawings]

FIG. 1 is a block diagram of a magnetic recording / reproducing apparatus according to an embodiment of the present invention, FIG. 2 (a) is a diagram showing a track pattern during one-channel recording / reproduction, and FIG. 2 (b) is a two-channel recording / reproduction. FIG. 3 shows a track pattern of FIG.
FIG. 4 shows a track pattern and a change in tape running speed in a switching portion when switching from channel recording / reproduction to 2-channel recording / reproduction. FIG. 4 shows respective timings when switching from 1-channel recording / reproduction to 2-channel recording / reproduction. FIG. 5 is a diagram showing a change in track pattern and tape running speed at a switching portion when switching from 2-channel recording / reproduction to 1-channel recording / reproduction, and FIG.
FIG. 7 is a diagram showing each timing when switching from channel recording / reproduction to one channel recording / reproduction, FIG. 7 is a diagram showing a magnetic head arrangement and a recording track pattern on a magnetic tape in a conventional magnetic recording / reproducing apparatus, and FIG. FIG. 9 is a block diagram showing a recording signal processing system in the conventional apparatus, and FIG. 9 is a diagram showing recording data distribution in a conventional apparatus. 1 is a rotating drum, 2a is a first magnetic head, 2b is a second magnetic head, 4 is a magnetic tape, 9a is a first channel recording video signal, and 9b is a second channel recording video signal. In the drawings, the same reference numerals indicate the same or corresponding parts.

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-50-99519 (JP, A) JP-A-1-191304 (JP, A) JP-A-3-63901 (JP, A)

Claims (1)

(57) [Claims] A pair of magnetic heads for recording and reproducing information of a first channel and a second channel each consisting of a video signal or an audio signal on a magnetic tape; A rotating drum that traces a magnetic tape and scans N tracks (where N ≧ 1) during one cycle of the information;
1. In a helical scan type magnetic recording / reproducing apparatus capable of simultaneously recording and reproducing information of a second channel on the same magnetic tape, a pair of the magnetic heads mounted on the rotating drum are provided during one cycle of the information. A drum rotation driving means for driving the rotation drum so as to scan at least 2 × N tracks; and when recording and reproducing the information of the first and second channels simultaneously, one of the first and second channels A tape running means for running the magnetic tape so as to be twice as fast as the speed of recording / reproducing the information of the channel; and a case of simultaneously recording the information of the first and second channels, When recording information of one of the first and second channels, one time compression means for time-compressing the information of the one channel; One recording signal processing means for processing the information time-compressed by the time compression means and outputting the processed signal to the pair of magnetic heads; and processing the information output from the pair of magnetic heads during reproduction. When simultaneously reproducing the time-compressed information of the first and second channels output from one reproduction signal processing means and the reproduction signal processing means, the information for two channels is time-expanded. And a time expansion means for time-expanding the information of one channel when reproducing the time-compressed information of one of the first and second channels. Playback device.