JPH0797869B2 - Magnetic recording / reproducing method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus such as a video tape recorder for recording / reproducing video signals and audio signals using a magnetic tape.

2. Description of the Related Art In the field of conventional video tape recorders for business use and broadcasting (abbreviated as VTRs), a method has been developed in which a color video signal is decomposed into two-channel component signals of a luminance signal and a color signal, and recorded and reproduced. ing. For example, it is a VTR called M format or β-CAM, which is a recording method as described in Broadcasting Technology Magazine, October 1982, pages 872 to 890, and a TV called M II format. The recording method is as described in Technical Report VR70-2, pages 7 to 12 of the Johns Society. These two-channel component type VTRs have a color signal track adjacent to a luminance signal track in a recording track recorded on a magnetic tape. Therefore, the azimuth angle between the luminance signal recording head and the color signal recording head is large. However, if overwriting recording is performed with solid writing without a guard band, unnecessary signal components will appear as interference during playback, and as a result, the playback image quality will be greatly degraded. Has not been overwritten without a guard band. That is, the two-channel component type VTR requires a guard band, which causes a problem of poor recording efficiency.

Furthermore, the tape feed amount determined for each method is single,
For example, there is a problem that it is not possible to properly use the recording / reproducing time for the same tape such as the standard mode and the long time mode in the VHS system which is one of the home VTR systems.

An example of the above-mentioned conventional two-channel component type VTR will be described below with reference to the drawings. FIG. 3 is a block diagram of a main part of a conventional two-channel component VTR. In FIG. 3, for example, a luminance signal as shown in FIG. 2A is input to the input terminal 18. The input terminal 19 is supplied with, for example, a time axis compression multiplexed color signal as shown in FIG. 2B. Here, as a conventional example, a channel component signal is formed of a luminance signal and a time axis compression multiplexed color signal. Input terminal
The luminance signal input from 18 arrives at the FM modulator 20, is frequency-modulated (FM) and is recorded on the magnetic tape by the magnetic heads 22 and 24, and is also reproduced by the magnetic heads 22 and 24 during reproduction. Is demodulated in the FM demodulator 27 and output from the output terminal 29. On the other hand, the time-axis compression-multiplexed color signal input from the input terminal 19 reaches the FM modulator 21, is FM-recorded on the magnetic tape by the magnetic heads 23 and 25, and is reproduced by the magnetic heads 23 and 25. The reproduced time-axis compression multiplexed signal reproduced is demodulated in the FM demodulator 28 and output from the output terminal 30. In the conventional example, for example, the second
Recording patterns on the magnetic tape 29 of the luminance signal and the time axis-compressed color signal shown in FIGS. A and B are as 401, 403, 405 and 402, 404, 406 in FIG. 4, respectively.

Problems to be Solved by the Invention In a conventional two-channel component VTR, a guard band is used to suppress crosstalk interference between adjacent tracks.
There is 36, and there is a problem that the recording density is lower than that of solid writing and overwriting recording. Further, there is a big problem that the recording / reproducing time for the same tape such as the standard mode and the long time mode cannot be used properly. In view of the above problems, the present invention newly provides a two-channel component VTR capable of improving the recording density of the two-channel component VTR and making the recording / reproducing time for the same tape two or more kinds.

Means for Solving the Problems In order to solve the above-mentioned problems, in the present invention, a specific four on a rotating cylinder of a two-channel component VTR is used.
A magnetic head mounted at a specific position on a rotating cylinder such that the relative positional relationship of the center line or one end line of each running track of each magnetic head changes in a similar manner to the feeding speed of a plurality of magnetic tapes. , And a drive system having a plurality of tape feeding speeds.

Operation The present invention realizes high-density recording without a guard band even though it is a two-channel component VTR with the above-mentioned configuration, and further has two or more kinds of recording / reproducing time for the same tape, such as a standard mode and a long time mode. VT
Enables the realization of R.

Embodiment One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of essential parts in an embodiment of the present invention. In FIG. 1, for example, a luminance signal as shown in FIG. 2A is inputted to the input terminal 1, and a time axis compressed color signal as shown in FIG. 2B is inputted to the input terminal 2. . Then, the two input signals enter the switcher 3 and are switched every horizontal synchronization period, and the luminance signal and the time axis compressed color signal as shown in FIGS. 2C and 2D are alternately switched every horizontal synchronization period. It is converted into a signal having a different form. The signal of FIG. 2C is frequency-modulated by the FM modulator 4 and recorded on the magnetic tape by the magnetic heads 7 and 9. The signal shown in FIG. 2D is delayed by the delay circuit 5 by the relative time difference T ₁ on the magnetic tape, which is determined by the positional relationship between the magnetic heads 7 and 9 and the magnetic heads 8 and 10, and reaches the FM modulator 6, where it is magnetized. It is recorded on the magnetic tape by the heads 8 and 9. The recording track pattern of the signal recorded on the magnetic tape 31 is shown in FIG. In FIG. 5, the arrow 32 indicates the scanning direction of the magnetic heads 7, 8, 9, and 10, and the arrow 33 indicates the running direction of the magnetic tape 31. Recording track 50
Recording tracks 1, 505 are recording tracks recorded by the magnetic head 7, recording tracks 502, 506 are recording tracks recorded by the magnetic head 8, recording tracks 503 are recording tracks recorded by the magnetic head 9, and recording tracks 504 are Recording tracks recorded by the magnetic head 10. Since the magnetic heads 7 and 8, 9 and 10 are mounted at different positions on the rotating cylinder by an angle θ, the relative time difference T ₁ of the magnetic head scanning on the magnetic tape having the position angle difference θ is shown in FIG. 2D. If the signal is delayed, a recording track pattern as shown in FIG. 5 can be obtained. In FIG. 5, the luminance signal Y is located adjacent to the luminance signal Y, and the color signal C is located adjacent to the color signal C.
For this reason, even if overwriting recording (solid writing) is performed, interference from adjacent tracks can be suppressed to a low level due to image correlation, so high-density recording without guard bands by overwriting recording is possible. Becomes Needless to say, as shown in FIG. 5, azimuth recording between tracks is an effective means for overwriting recording.

Next, even in the long time mode in which the tape running speed is changed to 1 / n (n is a number n> 1), the recording track pattern of each magnetic head becomes similar to that during normal running. Consider the case where other tracks are not completely overwritten. Now, let us say that the central angle of the magnetic heads 7 and 8 in FIG. 1 with respect to the central axis of the rotating cylinder is θ, the relative height difference is Δh, and the same applies to the magnetic heads 9 and 10. The recording track width in the standard mode is TW ₁ , and the track pitch, which is the amount of tape fed while the rotating cylinder rotates 180 °, is TP ₁ . In addition, the recording track width and the track pitch in the long time mode are TW ₂ and TP ₂ , respectively. Conditions for the long-time mode recording track pattern to be similar to the standard mode recording track pattern in FIG. 5 can be obtained with reference to FIG. That is, when the track pitch is TP and the magnetic head 8 is at the same position on the cylinder rotation axis as the magnetic head 7, the relative height difference of the magnetic head 8 with respect to the magnetic head 7 is Becomes Therefore, in order to make the recording track patterns similar to each other in both the standard mode and the long time mode, the following two expressions may be satisfied.

From (1) and (2) By the way, in order for the track pattern to be similar, Because there is a relationship Becomes Also, to obtain the track pattern as shown in FIG. Therefore, θ = 90 °. θ = 90 ° (1)
Substituting into Ie To get Therefore, if the magnetic heads 7, 8 and 9 and 10 are positioned on the rotary cylinder at a central angle of 90 ° and a relative height of 0, the recording track will be used for any long time mode in which the tape feed is slower than the standard mode. The pattern is similar to that shown in FIG. Recording tracks 601, 605 are recording tracks recorded by the magnetic head 7, and recording tracks 602, 605
A recording track 606 is a recording track recorded by the magnetic head 8, a recording track 603 is a recording track recorded by the magnetic head 9, and a recording track 604 is a magnetic head 110.
It is a recording track recorded by. However, in FIG. 6, the scale in the tape feeding direction is multiplied by n.

As described above, since the recording track pattern similar to the recording track pattern in the standard mode can be obtained even in the long time mode, it is possible to suppress the interference from the adjacent track to a low level even when the overwriting recording is performed.

In the above-mentioned example, the case where the track patterns are similar to each other has been described, but the same effect also occurs in all cases where each track is not completely overwritten by another track.

Now, in the standard mode and the long time mode, the signals recorded as shown in FIGS. 5 and 6 are reproduced at the time of reproduction by the same magnetic head as at the time of recording. In FIG. 1, the signals reproduced by the magnetic heads 7 and 9 are received by the FM demodulator 12, and the output becomes a signal having the form shown in FIG. 2C, and after being delayed by T _{1 in the} delay circuit 14, The signal has the form shown in FIG. 2F. Further, the signals reproduced by the magnetic heads 8 and 10 enter the FM demodulator 13, and the output thereof becomes the signal of the form shown in FIG. 2E. The signals of the forms shown in FIGS. 2F and 2E are switched by the switcher 15 every horizontal synchronizing period to become the luminance signal and the time axis compressed color signal shown in FIGS. And are output from 17.

When the magnetic heads 7 and 8, 9 and 10 are mounted close to each other on the rotary cylinder as in the conventional example such as the M format and βCAM, and the recording track pattern of the standard mode is long as shown in FIG. The recording track patterns in the time mode cannot be recorded / reproduced because the video tracks overlap each other.

In the above description, the luminance signal and the time axis compression multiplexed color signal are used as the signals handled by the video signal recording device for recording each of the video signals divided into two channels. The same effect can be obtained even when the color difference signals are frequency-multiplexed signals. That is, the present invention is applied to various video signal recording devices in which the electromagnetic conversion unit can perform 2-channel recording. That is, the input signal to the recording circuit system may be a luminance signal and two types of color signals, or R signals, G signals, and B signals. Furthermore, even if it is a 1-channel signal in which a luminance signal and a line-sequential chrominance signal are time-axis compression-multiplexed like a MAC signal, they are applied. or,
The recording track pattern on the magnetic tape is not limited to the one shown in FIG. 5, and for example, the luminance signal and the color signal are switched every nH (n is a natural number), and the luminance signal is adjacent to the luminance signal. Even if a magnetic head is arranged so that the color signal is recorded adjacent to the color signal, the same effect can be obtained.

EFFECTS OF THE INVENTION In a two-channel component VTR, if each head for two-channel recording is mounted close to each other as in the conventional example, it is necessary to provide a guard band between the luminance signal track and the chrominance signal track. Becomes worse. Further, it is not possible to use a plurality of tape running modes such as a standard tape running mode and a long time mode during recording and reproduction.

However, as shown in the present invention, the position of the magnetic head on the rotating cylinder is set so that each track is not completely overwritten by another track in the shape of the running track of the magnetic head in both the standard mode and the long time mode. Central angle θ and relative height Δh of two magnetic heads)
And the shape of the magnetic head (for example, θ = 90 °, Δh = 0 as shown in equation (3)), the luminance signal on the recording track pattern on the magnetic tape in the standard mode and the long time mode. Since it is possible to record a luminance signal adjacent to the color signal and a color signal adjacent to the color signal, crosstalk between adjacent tracks can be remarkably reduced, and good video recording and reproduction can be performed.

Further, according to the present invention, crosstalk interference of FM recorded video signals from adjacent tracks can be reduced by the principle of reducing triangular noise of FM signals for different tape feed speeds, and solid writing without guard bands is performed. However, it is possible to reduce the crosstalk interference from the adjacent track having a large interference energy and reduce the triangular noise of the FM demodulation at the time of reproduction. According to the present invention, the conventional FM recording method
In the VTR, it is possible to suppress a large deterioration in image quality due to crosstalk interference with a video signal other than the sync signal portion due to the sync signal of the adjacent track, which causes a very large crosstalk interference.

[Brief description of drawings]

FIG. 1 is a block diagram of essential parts in an embodiment of the present invention, FIG. 2 is a signal waveform diagram of each part in FIGS. 1 and 3,
FIG. 3 is a block diagram of essential parts in the conventional structure, FIG. 4 is a recording track pattern diagram on a magnetic tape in the conventional structure, FIG. 5 is a recording track pattern diagram in the standard tape running mode in the present invention, and FIG. FIG. 7 is a recording track pattern diagram in the long-time tape running mode in the present invention, and FIG. 7 is an explanatory diagram for explaining the dimensions of the recording track pattern on the magnetic tape and the positional relationship of the magnetic head. 11,26 …… Cylinder rotation direction, 34 …… Track pitch, 35 …… Track width, 36 …… Guard band, 37 …… 1H
(1 horizontal synchronization period).

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H04N 9/815 (56) References JP 61-265990 (JP, A) JP 60- 113365 (JP, A) JP 62-31294 (JP, A) JP 62-219892 (JP, A)

Claims (3)

[Claims] 1. In a magnetic recording / reproducing apparatus for recording and reproducing each of component video signals divided into two channels on a magnetic tape, a tape feed speed changeover switch for changing tape feed to a plurality of tape feed speeds. A tape drive motor for changing the tape feed speed in response to a command from the tape feed speed changeover switch, signal processing means for converting the two-channel component signal into first and second recording signals, and the first and second Recording signals are recorded on the magnetic tape and reproduced from the magnetic tape, and a pair of first and second magnetic heads having the same track width, and heads forming a pair are arranged on the circumference of the rotating cylinder. And the first and second magnetic head pairs are respectively arranged in a circle of a rotating cylinder. 90 degrees above the center of rotation, and the electromagnetic conversion system, wherein the relative heights of one ends of the track portions of the magnetic head pair with respect to the plane of rotation are arranged equal to each other, and The first
Among the second recording signals, only the second recording signal is delayed by a specific time before recording, and the horizontal synchronizing signals of the first and second recording signals are adjacent to each other in the direction perpendicular to the head moving direction. And a delay unit for delaying only the reproduction signal of the first magnetic head among the first and second reproduction signals to compensate for the time difference caused by the delay of the second recording signal. And signal processing means for converting the second reproduction signal into a two-channel component signal, and the recording track widths of the tracks respectively recorded by the magnetic head with respect to an arbitrary traveling speed of the magnetic tape are mutually A magnetic recording / reproducing method characterized in that they are substantially equal. 2. The magnetic recording / reproducing according to claim 1, wherein the two magnetic heads constituting the head pair have the same azimuth angle, and one head pair has different azimuth angles. Method. 3. The magnetic recording / reproducing method according to claim 1, wherein the specific delay time is half the horizontal scanning period.