JPH07107722B2 - Magnetic recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention enables simultaneous recording of signals of a plurality of channels onto a tape-shaped magnetic recording medium (hereinafter referred to as a magnetic tape). The present invention relates to a magnetic recording / reproducing device.

[Conventional technology]

Due to improvements in magnetic recording density due to advances in electronic technology and precision processing technology in recent years, and the development of digital signal processing technology, digital magnetic recording of audio signals is now realized, and digitization of image signals is also becoming possible. It is being promoted. However, since a digital signal requires a band 10 times or more as large as that of an analog signal, for example, in order to record a digital image signal by a magnetic recording / reproducing device of a VTR, compared to the case of an analog image signal, ( B) Increase the relative speed between the magnetic tape and the magnetic head. (B) Divide the image signal into multiple channels. (C) Increase the recording density by changing the material of the magnetic tape and magnetic head. And so on. this house,
As for (b), compared to other methods, 1. The band of the signal to be recorded and reproduced can be reduced to 1 / n times. (N
Is the number of channels) 2. There are few mechanical problems such as head touch and tape damage, and reliability problems.

Etc., and is more effective than other means.

The means for dividing the signal to be recorded into a plurality of channels as described above is effective not only for digital signals but also for analog signals. For example,
As shown in FIG. 8, a signal photographed by the image pickup unit S at a high speed of n times, that is, a signal in which a video signal for one field is formed in a period of 1 / n of one field period of a normal video signal, A signal converter C including a frame memory or the like converts the signal of each field into an n-phase n-channel signal that is time-axis expanded by n times, and records it by the n-channel simultaneous recording device R. According to this, the imaging unit S
Requires n times the normal band, but the other parts need only use the normal band.

Conventionally, as shown in FIG. 9 and FIG. 10, it is conceivable that the image signal or the like is divided into a plurality of channels as described above and the recording and reproducing are simultaneously performed on a magnetic tape or the like. In the figure, the number of channels n is three.

As shown in FIG. 9, the rotary drum 1 having a cylindrical shape has 2n magnetic heads, that is, six magnetic heads 2A, 2B, 3A, 3B, 4A, 4B.
Are arranged at intervals of 60 °. Also,
Three sets of magnetic heads 2A and 2 with a phase difference of 180 °
Each of B, 3A and 3B, 4A and 4B is assigned one system of the signal divided into three systems, and the magnetic tape wound around the rotary drum 1 over 180 ° by the loading posts 5 and 5 '. Simultaneous recording and reproduction of signals of three systems to T are performed. In this case, if the azimuth angles of the magnetic heads having the suffixes A and B are changed, the tracks T ₁ , T formed on the magnetic tape T as shown in FIG. in _2, T ₃ ......, can also be varied azimuth angles of tracks adjacent to each other, thereby enabling high-density recording of the guard band-less.

As described above, according to the above apparatus, it is possible to record a signal, such as an image signal, which has an extremely wide band when digitized, by reducing the band to 1 / n (in this case, 1/3).
Moreover, in this apparatus, the tape feed speed can be set to 1/3 and only one system of signals can be recorded by using one set of magnetic heads such as heads 2A and 2B. If the magnetic heads are arranged in the same manner, it is possible to provide compatibility with the existing single-system signal-dedicated device, and it is evaluated as highly useful.

[Problems to be solved by the invention]

However, in the magnetic recording / reproducing apparatus as described above, 2n magnetic heads are required for simultaneous recording of n channels, and moreover, a transmission system such as a rotary transformer, a preamplifier, etc. are provided in the number of magnetic heads. Therefore, there is a problem in that the number of devices must be increased, which increases the scale of the entire apparatus and increases the cost.

It is also considered that the same number of magnetic heads as the number of divided channels are provided on the rotary drum, and a magnetic tape is wound around the drum at an angle of 300 ° or more for recording / reproduction. Since one portion of the recording signal is lost during one rotation period, a circuit for interpolating this portion must be provided, or a circuit for performing time axis compression for each recording signal of each track must be provided. There is the problem of complication.

The present invention has been made in view of the above-mentioned problems, and it is possible to simultaneously record signals of a plurality of channels without loss in a small-scale and inexpensive structure without significantly increasing the number of magnetic heads, and to perform recording. An object of the present invention is to provide a magnetic recording device capable of recording a tracking control pilot signal with a simple configuration for reliably reproducing the generated signals of a plurality of channels without a tracking error.

[Means for solving problems]

The present invention is a magnetic recording apparatus for sequentially supplying video signals to four magnetic heads arranged at predetermined angular positions on a rotary drum to record them as tracks on a magnetic tape,
A signal distributing means for sequentially supplying a recording signal to each of the magnetic heads in a predetermined order, and a superposing means for sequentially superposing a predetermined pilot signal on the recording signal so as to obtain a reproduction pilot signal which is repeated in a four-track cycle during reproduction. And a second recording mode in which a video signal is recorded for each track by sequentially using each of the magnetic heads and a second recording mode in which a video signal is recorded for each track by using the plurality of magnetic heads. Switching means for switching the superimposing destination of the pilot signal in the superimposing means, and the switching means makes the recording order of the pilot signals on the magnetic tape coincident by varying the superimposing destination according to each recording mode. It is configured in.

[Action]

According to the present invention, the four magnetic heads are sequentially used to achieve 1
First recording mode for recording video signals track by track and 4
By the switching means for switching the superimposing destination of the pilot signal to the recording signal according to the second recording mode in which the video signals are recorded on a plurality of tracks by using a single magnetic head, the superimposing destination is changed according to each of the recording modes. Since it is variable, the pilot signals reproduced in the same order can be obtained regardless of which recording mode is used for recording.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 7. The same or corresponding parts as those of the conventional example are designated by the same reference numerals, and the detailed description thereof will be omitted. The present embodiment is an embodiment in which the present invention is applied to an apparatus having a mode for recording only one channel signal and a mode for simultaneously recording three channel signals.

FIG. 1 is a diagram showing a configuration around a rotary drum of an apparatus that realizes simultaneous recording and reproduction of n channels (in this case, 3 channels). In the figure, four magnetic heads 6A, 6B, 6C and 6D are arranged at a predetermined angular position on the rotary drum 1 at equal intervals (in this case, 9
They are arranged at an interval of 0 °). Further, the rotating drum 1 has a loading post 7, 7'as a recording medium winding means.
By The magnetic tape T is wound over the strong magnetic field (in this case, slightly higher than 270 °).

FIG. 2 is a diagram showing the configuration of a recording circuit for simultaneously recording three-channel signals on the magnetic tape T using the magnetic heads 6A, 6B, 6C and 6D. Drawing, 8a, 8b, 8c is a modulator for modulating the signals S _1, S _2, S ₃ of 3 channels sent from the signal converting unit C, etc. Each 9 represents the rotational speed and phase of the rotary drum 1 A switching signal generator that outputs a head switching signal Sc based on the FG signal and the PG signal, and 10 is a mixture of the signals S ₁ , S ₂ and S ₃ from the modulators 8a, 8b and 8c in the subsequent stage in accordance with the head switching signal. A switching circuit for appropriately switching and transmitting to the devices 11a, 11b, 11c, 11d, 12 is a pilot signal generator for generating pilot signals having m kinds of low frequencies (m is a divisor of n + 1 except 1), Then, since the signals to be recorded are three channels as described above, the four kinds of pilot signals f ₁ , f ₂ , f ₃ , f ₄ are used as a divisor of 3 + 1 (= 4).
Input to a, 11b, 11c, 11d. The pilot signals f ₁ , f ₂ , f ₃ and f _{4 used} are, for example, f ₁
= 102.544KHz, f ₂ = 118.95KHz, f ₃ = 165.210KHz, f ₄ = 148.
689 KHz or the like is used. Reference numeral 13 is a pilot signal switching circuit for switching pilot signals f ₂ and f ₄ input to the mixers 11b and 11d, and the switching is performed according to the input mode signal. Reference numerals 14a, 14b, 14c and 14d denote amplifiers for amplifying the mixed signals of the pilot signal and the three-channel signals S ₁ , S ₂ and S ₃ respectively by the mixers 11a, 11b, 11c and 11d, the outputs of which are the magnetic signals. It is supplied to the heads 6A, 6b, 6C, 6D.

Here, the switching circuit 10 is configured as a signal distribution means for sequentially supplying the recording signals to the magnetic heads 6A, 6B, 6C and 6D in a predetermined order, and the mixers 11a, 11b, 11c and 11d are used for reproducing four tracks. It is configured as a superimposing means that sequentially superimposes a predetermined pilot signal on the recording signal so that a reproduced pilot signal repeated in a cycle can be obtained. Further, the pilot signal switching circuit 13 uses a first recording mode in which video signals are recorded one track at a time by sequentially using the magnetic heads 6A, 6B, 6C and 6D and a plurality of magnetic heads 6A, 6B, 6C and 6D. The mixer 11a, 11b, 11c, 11d is configured as switching means for switching the superimposing destination of the pilot signal in accordance with the second recording mode for recording the video signal for each of a plurality of tracks. By changing the superimposing destination, the recording order of pilot signals on the magnetic tape is made to match.

In the recording circuit having the above structure, first, the case where only the signal S _{1 of} one channel is recorded will be described. In this case, the head switching signal Sc from the switching signal generator 9 causes
The connection of the switching contact 10A in the switch circuit 10 is sequentially switched to the terminals a, b, c, d with one cycle of 3/4 rotation of the rotary drum 1, and the signal S _{1 of} one channel passed through the modulator 8a is mixed by the mixer 11a. ,
It is sequentially switched to 11b, 11c, 11d and output. This time,
The pilot signal switching circuit 13 has switching contacts 13A and 13B connected to terminals b and a, respectively, according to a mode signal representing the 1-channel recording mode.
The pilot signals f ₁ , f ₂ , f ₃ , and f ₄ output from 2 are sequentially mixed with the signal S _{1 of the} one channel by the mixers 11a, 11b, 11c, and 11d. Then, the mixed signals are amplified by amplifiers 14a, 14b, 14c, 14d, respectively, and then the magnetic head 6
The data is recorded on the magnetic tape T sequentially from A, 6B, 6C and 6D. The track pattern on the magnetic tape T at this time is shown in FIG.
At this time, as shown in the figure, pilot signals are repeatedly recorded in the order of f ₁ , f ₂ , f ₃ , f _{4 on} each track T ₁ , T ₂ , ....

Next, the operation of recording a 3-channel signal will be described. In this case, the feeding speed of the magnetic tape T is three times that in the 1-channel recording mode, and the pilot signal switching circuit 13 has its contacts 13A and 13B at terminals respectively.
It is connected to a and b. In addition, each contact 10 in the switching circuit 10
Connection with terminals a, b, c, d of A, 10B, 10C is based on the head switching signal Sc.
Accordingly, 3/4 rotation of the rotary drum 1 is set as one cycle, and the rotation is sequentially switched with a time difference of 1/4 rotation. Therefore, the signals S ₁ , S ₂ , S _{3 of} the three channels that have passed through the modulators 8a, 8b, 8c are sequentially switched and input to the mixers 11a, 11b, 11c, 11d, respectively. At this time, the pilot signals f ₁ , f ₄ , f ₃ , f ₂ are input to the mixers 11a, 11b, 11c, 11d, respectively, and these signals are mixed with the signals of the three channels, and the amplifier 14a ,
After being amplified by 14b, 14c and 14d, it is supplied to the magnetic heads 6A, 6B, 6C and 6D and recorded on the magnetic tape T. FIG. 4 shows the switching state of the channel signals S ₁ , S ₂ , S ₃ supplied to the magnetic heads 6A, 6B, 6C, 6D at this time. Further, FIG. 5 shows each of the tracks T ₁ , T ₂ , T ₃ , ... formed by the above recording operation.
Is shown. In the figure, f ₁ , f ₂ , f ₃ , and f ₄ represent pilot signals when recording is performed by switching the switching contacts 13A and 13B of the switching circuit 13 from the 1-channel mode as described above, Further, (f ₂ ) and (f ₄ ) show pilot signals when recording is performed with the switching circuit 13 in the same state as in the 1-channel mode. That is, the mixers 11a, 11b, 11c,
When the pilot signals f ₁ , f ₂ , f ₃ , and f ₄ are input to 11d, respectively, the arrangement of pilot signals recorded on the magnetic tape T in the 3-channel mode is the reverse of that in the 1-channel mode. Therefore, in this embodiment, the switching circuit 13 is used to switch the arrangement of the pilot signals f ₄ and f ₂ and record the pilot signals in the same arrangement as in the 1-channel mode. When it is not necessary to make the arrangement of pilot signals the same as in the 1-channel mode as described above, the switching circuit 13 is unnecessary.

FIG. 6 is a diagram showing a configuration of a reproduction circuit for a signal recorded by the recording circuit.

In the figure, 13 is a timing signal generator for generating a head switching signal S'c and a timing signal St based on the input FG signal and PG signal, and 14 is a magnetic signal in response to the head switching signal S'c and the mode signal. Head 6A, 6B, 6
A head switching circuit that appropriately switches the reproduction signals output from C, 6D via the amplifiers 15a, 15b, 15c, 15d and outputs them as 3-channel signals to the demodulators 16a, 16b, 16c in the subsequent stage, the internal configuration of which is This is similar to the head switching circuit 10 in the recording circuit. Reference numeral 17 is a low-pass filter for extracting a low-frequency pilot signal from the signal of the first channel output from the head switching circuit 14, and 18 is reference pilot signals f ₁ and f ₂ according to the timing signal St from the timing signal generator 13. ,
Reference pilot signal generator for generating f ₃ and f ₄ , 19 is a tracking error detection circuit for detecting the tracking error signal Se of the reproducing magnetic head based on the reference pilot signal and the reproducing pilot signal, 20 is a tracking error signal Se Based on this, a mode detecting circuit for detecting whether the reproduced portion is a portion recorded in the 1-channel mode or a portion recorded in the 3-channel mode. The mode signal output from this is a pilot signal generator 18 and a head switching circuit 14 Then, it is input to the capstan control circuit 21 and other control systems.

Based on the above configuration, the reproducing operation will be described next.

During reproduction of the recorded portion in the 1-channel mode, that is, during reproduction of the track pattern as shown in FIG. 3, the head switching circuit 14 switches in response to the head switching signal from the timing signal generator 13, and the 3-channel signals are sequentially output. Extracted from each magnetic head 6A, 6B, 6C, 6D, this is demodulator 1
Demodulated by 6a. At the same time, the head switching circuit 14
The signal is output to the signal low-pass filter 17, and the reproduction pilot signals f ₁ , f ₂ , f ₃ , f ₄ are extracted here. Then, the error detection circuit 19 forms a tracking error signal indicating a tracking error amount by the four-frequency system using the reproduction pilot signal and the reference pilot signal, and based on this, the tape is moved by a capstan (not shown). The controlling capstan control circuit 21 performs tracking control.

When the recorded portion is reproduced in the 3-channel mode, that is, when the track pattern is reproduced as shown in FIG. 5, the control method of the switching circuit 14 is switched by the head switching signal S'c, and the magnetic heads 6A, 6B, 6C are switched. , 6D, the three-channel signals extracted from the three magnetic heads in contact with the magnetic tape T are input to the demodulators 16a, 16b, 16c in the subsequent stage, where they are demodulated. At the same time, the signal of the first channel input from the head switching circuit 14 is input to the low-pass filter 17 to extract the reproduction pilot signal, and the tracking error detection circuit 19 is generated as in the reproduction in the 1-channel mode. The tracking error signal Se is sent from the device, and the capstan control circuit 21 performs tracking correction. In addition, the error signal Se is the mode detection circuit 20.
The recording mode of the part being reproduced is detected by detecting the waviness of the tracking error signal due to the difference in tape running speed when the recording mode and the reproducing mode are different. . As the means for detecting the recording mode of the reproducing portion, the mode signal may be inserted into the digital signal for recording, and the mode may be detected by other means such as detecting the mode signal during reproduction.

This mode detection signal is used not only for switching the head and controlling the reproduction system, but also for switching the output of the reference pilot signal. That is, when the recording pilot signals are arranged in the same manner in the reproduction in the 3-channel mode as compared with the reproduction in the 1-channel mode, the arrangement of the reproduction pilot signals is in the reverse order, and it is necessary to switch the output order of the reference pilot signals. For example, when the pilot signals f ₄ and f ₂ are switched by the pilot signal switching circuit 13 in the 3-channel mode recording, the array of recorded pilot signals is f ₁ →
f ₂ → f ₃ → f ₄ , but the output order of pilot signals reproduced from the track that is the control target for the playback head of channel 1 during playback is f ₁ → f ₄ → f ₃ → f ₂ → f _The opposite of ₁ ...

Therefore, the generation order of reference pilot signals during 1-channel mode reproduction is f ₁ → f ₄ → f ₃ → f ₂ → f ₁
As is well known, when the reproduction pilot signal is multiplied, the frequency f _A (f ₂ −f ₁ = f ₃ −f ₄ ) included in the multiplied signal is obtained.
The component is always obtained from the preceding track with respect to the control target track, and the frequency f _B (= f ₄ −f ₁ = f ₃ −f ₂ ) component is always obtained from the following track. The tracking error signal is obtained by comparing the f _A component and the f _B component. However, the generation order of the reference pilot signal at the time of 3-channel mode reproduction is f ₁ → f ₄ → f ₃ → f ₂ → f ₁ …… means that the pilot signal reproduced from the control target track will also be f ₁ → f ₄ → f ₃ → f ₂ → f ₁ ……, so that f _A and f _B components are The obtained direction is reversed. Therefore, when the tracking error signal is formed by the same circuit, the generation order of the reference pilot signal in the three-channel mode reproduction must be f ₁ → f ₄ → f ₃ → f ₂ → f ₁ ...

When the switching circuit 13 is not used, the arrangement order of the pilot signals recorded as described above is reversed. In this case, the pilot signals reproduced from the control target track of the head of the first channel are in the same order as in the 1-channel reproduction mode, but the directions in which the f _A component and the f _B component are generated are opposite. Become. Therefore, in this case, the output order of the reference pilot signals may not be switched during reproduction in the 3-channel mode, but the tracking error signal may be inverted and supplied to the capstan control circuit 21.

The above is mainly described for recording and reproducing a digital signal. Next, a case of performing high-speed slow-motion reproduction by simultaneously recording three-channel signals by high-speed imaging and reproducing the signals in one-channel mode Describe.

In this case, if the three-channel mode recording is performed as in the above case, the track angle of the recording portion is different from the trace angle at the time of reproduction.
It is desirable to move the 6A, 6B, 6C and 6D by a bimorph or the like in a direction intersecting with the tracing direction for recording and to correct the recording track angle in advance. Further, the arrangement of pilot signals on the magnetic tape T must be arranged in the same order as in the 1-channel mode recording by the pilot signal switching circuit 13. In this way, the reproduction can be performed in the same manner as the 1-channel mode reproduction described above.

It is also possible to perform 1-channel mode reproduction in the same manner as described above without correcting the track angle during recording. However, the reproduction output in that case has a low level at both ends as shown in FIG. 7, and a signal dropout occurs.
Therefore, when recording a composite video signal, etc.,
It is necessary to devise to prevent noise from occurring on the screen, such as by applying a vertical sync signal to the part where this loss occurs and recording, and in this case, a means to compensate for the loss of the vertical sync signal is also necessary. is there.

On the other hand, it is also possible to drive the magnetic head by a bimorph or the like during reproduction to obtain a uniform reproduction output.

〔effect〕

As described above, according to the present invention, the signal distribution means for sequentially supplying the recording signals to the four magnetic heads arranged at the predetermined angular positions on the rotary drum in the predetermined order, and the four tracks during reproduction. Superimposing means for sequentially superimposing a predetermined pilot signal on the recording signal so as to obtain a reproduced pilot signal which is repeated in a cycle, and a first recording mode for recording video signals one track at a time by sequentially using each of the magnetic heads. Switching means for switching the superimposing destination of the pilot signal in the superimposing means according to a second recording mode for recording a video signal on a plurality of tracks using a plurality of the magnetic heads, and the switching means, Since the recording order of the pilot signals on the magnetic tape is made to match by varying the superimposition destination according to the mode, Without having to significantly increase the number of Tsu de,
With a small-scale and inexpensive structure, it is possible to simultaneously record signals of a plurality of channels without omission, and it is possible to reliably reproduce the recorded signals of a plurality of channels without a tracking error. Even when recorded in the recording mode, it is possible to obtain the reproduced pilot signals reproduced in the same order.

[Brief description of drawings]

1 is a plan view showing the structure around a rotary drum in an embodiment of the present invention, FIG. 2 is a circuit diagram showing the structure of a recording circuit in the same embodiment, and FIG. FIG. 4 is a diagram showing a track pattern when channel mode recording is performed, FIG. 4 is a diagram showing a signal supply state to each magnetic head when performing three channel mode recording in the one shown in FIG. 2, and FIG. FIG. 6 is a diagram showing a track pattern at the time of 3-channel mode recording shown in FIG. 2, FIG. 6 is a circuit diagram showing a configuration of a reproducing circuit corresponding to the recording circuit of FIG. 1, and FIG. 7 is shown in FIG. 3 depending on
Channel mode Output waveform diagram showing an example of reproducing the recorded portion in 1-channel mode, FIG. 8 is a conceptual diagram of a high-speed photography recording device, and FIG. 9 is a rotary head in a conventional 3-channel signal simultaneous recording device. FIG. 10 is a plan view showing the peripheral structure, and FIG. 10 is a view showing a track pattern recorded by the one shown in FIG. 1 ... Rotating drum 6A, 6B, 6C, 6D ... Magnetic head 7,7 '... Road dig post as recording medium winding means 10 ... Switching circuit (signal supply means) 11a, 11b, 11c, 11d ... … Mixer (signal supply means) 12 …… Pilot signal generator (signal supply means) 13 …… Pilot signal switching circuit (signal supply means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Hirata, 770 Shimonoge, Takatsu-ku, Kawasaki-shi, Kanagawa Canon Inc. Tamagawa Plant (56) Reference JP-A-60-185210 (JP, A) JP-A Sho 61-126656 (JP, A)

Claims (1)

[Claims] 1. A magnetic recording device for sequentially supplying video signals to four magnetic heads arranged at predetermined angular positions on a rotary drum to record them as tracks on a magnetic tape. Signal distributing means for sequentially supplying recording signals in a predetermined order, superimposing means for sequentially superimposing a predetermined pilot signal on the recording signal so that a reproduction pilot signal repeated at a 4-track cycle at the time of reproduction, A pilot signal in the superposing means according to a first recording mode in which a head is sequentially used to record a video signal for each track and a second recording mode in which a plurality of magnetic heads are used to record a video signal for each track. Switching means for switching the superimposing destination of the recording medium, the switching means changing the superimposing destination according to each recording mode. A magnetic recording device characterized in that the recording order of pilot signals on a magnetic tape is matched.