JPH0515359B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic recording method, and in particular, magnetic recording of a frequency modulated luminance signal and two types of color difference signals separately and simultaneously onto two tracks using a rotating head. The present invention relates to a method of forming a record on a recording medium.

Conventional technology Currently, helical scan magnetic recording and reproducing devices (VTR) use 1/2 inch wide magnetic tape.
Since the band that can be recorded and reproduced for home use is relatively narrow, of the luminance signal and carrier color signal separated from the color video signal, the luminance signal is frequency-modulated to become a frequency-modulated wave, and the carrier color signal is converted into a frequency-modulated wave. A so-called low-pass conversion color recording and reproducing method is adopted in which the converted carrier color signal is frequency-division multiplexed onto the frequency-modulated luminance signal, and this frequency-division multiplexed signal is recorded on a magnetic tape and reproduced. Furthermore, in order to improve tape usage efficiency, a guard bandless recording method is adopted in which the azimuth angles of each rotating head for recording adjacent tracks are made to be different. On the other hand, commercial VTRs intended for broadcasting, especially those with built-in cameras, have the same tape width as home VTRs, with the aim of making the device smaller and lighter and improving the quality of the reproduced color video signal. on magnetic tape,
A system is adopted in which the luminance signal and the color signal are recorded separately on separate tracks using a rotating head, and a guard band is provided between adjacent tracks for recording and reproduction.

In the above-mentioned color video signal recording and reproducing apparatus using the so-called Y/C separate recording and reproducing method, the luminance signal and the color difference signal are recorded on separate tracks and reproduced.
Moiré, which occurs when VTRs simultaneously record and reproduce FM luminance signals and low frequency conversion carrier chrominance signals on the same track on a non-linear transmission magnetic tape, does not occur, and both luminance signals and chrominance signals are recorded and reproduced. Each band can be made sufficiently wide, and since the low frequency conversion carrier color signal is not recorded biased by the FM luminance signal, the S/
N (signal-to-noise ratio) can be improved, and from the above, it is possible to obtain a reproduced color video signal of higher image quality than that of a VTR using the low frequency conversion color recording and reproduction method.

However, since all of the above-mentioned conventional recording and reproducing apparatuses using the Y/C separation recording and reproducing method are provided with a guard band, there is a problem that the magnetic tape is used inefficiently. Furthermore, if the rotary head crosses the guard band and scans adjacent tracks during playback, the brightness will be The FM color difference signal (or FM luminance signal) is reproduced by the signal rotary head (or color difference signal rotary head), and there is no field correlation between the reproduced signals of both tracks, so the above-mentioned low frequency conversion color There is also the problem that it is not possible to use the crosstalk cancellation method that uses field correlation, which is used in home VCRs that use the recording and playback method, resulting in reproduced images with noticeable crosstalk. Ta.

For this reason, a device (AST: Auto Scan Tracking) is used to control the scanning position of the rotary head so that the rotary head accurately scans the recording track trace using a separately recorded tracking signal, etc. to reduce the above-mentioned crosstalk. However, in this case, there are problems such as an additional mechanism, circuit, etc. for such a device, resulting in a significant increase in cost.

Therefore, the present applicant previously proposed in Japanese Patent Application No. 60-185587, Japanese Patent Application No. 60-195643, etc. that the track on which the first information signal is recorded and the track on which the second information signal is recorded are the same track. A magnetic recording method has been proposed which solves the above-mentioned problems by forming records separately and simultaneously during the scanning period and by alternately switching the arrangement in the longitudinal direction of the tape for each track scanning period.

Problems to be Solved by the Invention However, in the magnetic recording method proposed above, a frequency modulated luminance signal (FM luminance signal) is recorded on one track as the first information signal,
When two types of color difference signals are recorded in a predetermined signal form on the other track as the second information signal, a wide guard band is formed between each recording track of the first and second information signals that are formed at the same time. is formed, so there is almost no crosstalk from adjacent tracks between them, so there is no problem. Since recording is performed with a very small guard band or no guard band in between,
Crosstalk from adjacent tracks becomes a problem during playback.

However, the azimuth angles of the rotating heads forming two adjacent information signal recording tracks of the same type are different from each other, and since the color difference signal in the above-mentioned predetermined signal form has a relatively high frequency, the azimuth angle is different from each other. A loss effect can be expected, and crosstalk from adjacent tracks can be made almost non-problematic by recording in H alignment. In addition, when recording the carrier color signal obtained by carrier suppression quadrature two-phase modulation of the above two types of color difference signals, even if the recording frequency band is a low frequency band where azimuth loss effect cannot be expected. The well-known PS (Phase Shift) as previously disclosed by the applicant in Japanese Patent Publication No. 56-9073
It is well known that by applying this method, crosstalk from adjacent tracks can be removed using a comb filter during playback.

On the other hand, in order to obtain high resolution, the FM luminance signal has an extremely wide band as shown in the frequency spectrum in Figure 5, and the above-mentioned azimuth loss effect is expected for the low frequency components of the lower sideband shown by the broken line. Can not. In this case, the above-mentioned PS
However, although the PS method can be applied to a balanced modulated wave with a fixed carrier frequency such as a carrier color signal, for a frequency modulated wave signal, the frequency of the carrier wave changes instantaneously depending on the information. The PS method cannot be applied because it changes instantaneously.

For this reason, for example, when a still image displayed as a vertical line with a repetition frequency N·f _H (where f _H is the horizontal scanning frequency and N is a natural number) is recorded on the screen S as shown in FIG. of a certain recording track
The frequency spectrum of the FM luminance signal, as shown by the solid line in Fig. 8, has a lower sideband component appearing at a frequency position _{f1 '} that is N· _fH lower than the carrier wave f1,
During playback, lower sideband components are mixed into the same frequency position f ₁ ' as crosstalk from adjacent tracks, and their phases are generally shifted significantly due to recording jitter, so this effect appears on the edges of the screen. There is a problem in that the beats appear as beats, and the positions of the beats appear to move with time, which significantly impairs the image quality. In addition, adjacent FM
If H-aligned recording is performed in which the horizontal synchronizing signal recording positions of the luminance signal recording track are aligned in the track width direction, the above crosstalk can be significantly reduced, but due to jitter, etc., in reality, H-aligned recording is completely impossible. This required considerable precision and was difficult.

Therefore, an object of the present invention is to provide a magnetic recording method that solves the above problems by making the recording carrier wave frequencies of adjacent FM luminance signal recording tracks different from each other by an odd multiple of f _H /2. shall be.

Means for Solving the Problems The magnetic recording method according to the present invention provides first and second magnetic recording devices attached to opposite positions on the rotating surface of a rotating body.
and a rotary head mounted at opposing positions on the rotating surface of the rotating body, and close to the respective mounting positions of the first and second rotating heads in the rotational direction of the rotating body, and , the third ones are respectively attached at different heights in the direction of the rotational axis of the rotating body.
and a fourth rotary head, among the rotary heads, the frequency modulated luminance signal is supplied to the first and fourth rotary heads having gaps of mutually different azimuth angles, and a predetermined signal format is provided. supplying the two types of color difference signals determined to be different from each other to second and third rotary heads having gaps of different azimuth angles, and the first and third rotary heads simultaneously recording during one track scanning period; The second and fourth rotary heads perform recording simultaneously during the next one track scanning period using a magnetic recording method that uses the carrier wave frequency of the frequency modulated luminance signal recorded by the first rotary head and the fourth rotary head. The frequency of the difference from the carrier frequency of the frequency-modulated luminance signal to be recorded is selected to be an odd multiple of f _H /2 (where f _H is the horizontal scanning frequency),
A frequency modulated luminance signal is recorded.

Operation: During one track scanning period, the first and third rotary heads separately and simultaneously form first and second tracks having wide guard bands between them, and during the next one. During the track scanning period, the second and fourth rotary heads form third and fourth tracks having wide guard bands between each other, and thereafter a wide guard band is formed between each other every track scanning period. 2 parallel tracks are sequentially formed, and recording is performed between adjacent frequency modulated luminance signal recording tracks recorded by the first and fourth rotary heads and by the second and third rotary heads. Recording is performed with a very small guard band or without providing a guard band between adjacent color difference signal recording tracks. In addition, since the frequency-modulated luminance signal described above is recorded with its carrier wave frequency differing by an odd multiple of f _H /2 in adjacent tracks, the frequency-modulated luminance signal recorded on adjacent tracks is not crossed when reproduced. As shown by the broken line f _{2 '} in FIG. appears at a frequency position lower than N・_fH , and this is a frequency that is Δf=(=(2n+ ₁ ) _fH /2) farther away than the frequency component f1' of the lower sideband of the original reproduction track, so the azimuth Crosstalk of low frequency components in the lower sideband, where no loss effect can be obtained, becomes visually difficult to see on the screen.

Example Examples of the present invention will be described below.

FIG. 1 shows a block system diagram of one embodiment of the present invention. In the figure, a color video signal input to an input terminal 1 is corrected for level fluctuations by an AGC circuit 2, and then supplied to a comb filter 3, where it is separated into a luminance signal and a carrier color signal, respectively. The separated luminance signal is supplied to an adder circuit 8 through a low-pass filter 4, a clamp circuit 5, a pre-emphasis circuit 6, and a white/dark (W/D) clip circuit 7. On the other hand, a square wave (head switching pulse) with a period of two fields that is inverted every field enters the input terminal 9, and is supplied to the adder circuit 8 through the variable resistor 10.
As a result, a brightness signal in which the DC level of the output brightness signal of the W/D clip circuit 7 oscillates up and down every field is taken out from the adder circuit 8, and the FM
The signal is supplied to a modulator 11, where it is converted into a broadband FM luminance signal as shown in FIG. 5, and then supplied to the rotary heads H _M1 and H _M2 through a recording amplifier 12, respectively. As described above, the DC level of the input luminance signal of the FM modulator 11 oscillates vertically for each field, and the difference in the oscillation level is adjusted by the level adjustment of the variable resistor 10, so that the DC level of the input luminance signal of the FM modulator 11 is adjusted to the output terminal of the FM modulator 11. Since the frequency Δf is selected to be an odd multiple of 1/2 of the horizontal scanning frequency _fH ,
In the above FM luminance signal, the carrier frequency alternately increases and decreases by Δf every field.

On the other hand, the carrier color signal separated from the color video signal by the comb filter 3 is supplied to the decoder 13, where it is demodulated and converted into two types of color difference signals (R-Y) and (B-Y). be done. The color difference signals (R-Y) and (B-Y) are passed through the low-pass filter 14,
15, clamp circuits 16, 17, and pre-emphasis circuits 18, 19, respectively, to an adder circuit 20,
21, where the head switching pulse coming from the input terminal 9 is applied to the variable resistor 2.
It is added to the signal obtained by level adjustment in steps 2 and 23. As a result, the adder circuit 20 outputs a color difference signal (R
-Y) is extracted and supplied to the FM modulator 24. Similarly, from the adder circuit 21, a color difference signal (B-
Y) is extracted and supplied to the FM modulator 25.

The FM modulator 24 outputs a first signal obtained by frequency modulating a high frequency first carrier wave using a color difference signal (R-Y).
On the other hand, the FM modulator 25 outputs a second FM color difference signal obtained by frequency modulating a second carrier wave having a lower frequency than the first carrier wave with the color difference signal (B-Y). A signal is extracted. Here, the DC level of the input color difference signal of the FM modulators 24 and 25 oscillates up and down every field, and the difference in the vibration level is adjusted by the level adjustment of the variable resistors 22 and 23. The frequency Δf, which is an odd multiple of 1/2 of the horizontal scanning frequency _fH , is selected at the output end of the horizontal scanning frequency fH.
The carrier wave frequency of the second FM color difference signal is alternately increased or decreased by the frequency Δf for each field. FIG. 6 shows the frequency spectra of the first and second FM color difference signals in one field period, where is the frequency spectrum of the first FM color difference signal, and its carrier wave center frequency f _R is, for example, about 5 MHz. One is the frequency spectrum of the second FM color difference signal, and its carrier wave center frequency f _B is, for example, about 1 MHz.

The first FM color difference signal is supplied through a high-pass filter 26 to an adder circuit 28, where the second FM color difference signal is removed from unnecessary frequency components by a low-pass filter 27.
The signal is added to the FM color difference signal to form a frequency division multiplexed signal with a frequency spectrum as shown in FIG. 6, and then supplied to the rotary heads H _S1 and H _S2 , respectively.

Next, the arrangement of the rotary head in the present invention will be explained in detail. FIG. 2 shows an embodiment of the arrangement of the rotary head in the present invention. As shown in the figure, a first rotary head H _M1 and a second rotary head H _M2 are respectively mounted on the rotating surface of a rotating body such as a rotary drum.
The third rotary head H _S1 and the fourth rotary head H _M2 are installed at positions facing each other by 180 degrees on the rotating surface, and at the same height. A position that is behind H _M1 and H _S2 in the rotational direction by a distance c to be described later, and an upper rotational head H _M1 in the rotational axis direction of the rotating body.
It is installed at a position 45μm higher than the bottom edge of H _S2 . The track widths of these rotary heads H _M1 , H _S1 , H _M2 and H _S2 are each equal to 29 μm, and their azimuth angles are the same as those of the rotary heads standardized in the current low frequency conversion color recording/playback system VTR. The azimuth angle is selected to be the same as the azimuth angle, so that the azimuth angle of the rotating heads H _M1 and H _S1 is, for example, +6°, and that of the rotating heads H _M2 and H _S2 .
The azimuth angles of are selected to be −6°, respectively.

FIG. 3A is a more detailed view of the rotating heads H _S1 and H _M1 viewed from the sliding surface, and the distance c between them is set to a value that allows recording H side by side. rotating head
As shown in FIG. 3B, H _S1 and H _M1 are glued to the tip of a single head base 33 (the same applies to rotating heads H _S2 and H _M2 ).

Considering compatible playback on a home-use VTR using the current low frequency conversion color recording and playback system, the rotary heads H _M1 , H _M2 , H _S1 and H _S2 are installed, and the magnetic tape is rotated at an angle of just over 180°. The diameter of the rotating body that is wound obliquely over the angular range must be the same as the diameter of the rotating body of the home VTR mentioned above, and the scanning track trajectory of the rotating head when the magnetic tape stops traveling must be the same. The angle with respect to the longitudinal direction of the tape (still tilt angle) must also be the same as that of the above-mentioned home VTR.

Rotating heads H _M1 , H _M2 , H _S1 and H _S2 with the above configuration
As a result, a track pattern as shown in FIG. 4 is formed on the magnetic tape 29. The track pattern itself shown in Fig. 4 was originally filed by the present applicant in a patent application filed in 1983.
Although the track pattern is the same as that proposed in No. 195643, the present invention is not limited to this track pattern. In FIG. 4, two audio tracks 30 1 and 30 2 are formed along the tape longitudinal direction at the upper end of the magnetic tape 29, and two audio tracks 30 ₁ and 30 ₂ are formed at the lower end of the tape at a constant period (for example, one frame) along the tape longitudinal direction. ) A control track 31 is formed in which the control pulses of 1.) are recorded. In addition, T _Y1 , T _Y2 , and T _Y3 are tracks, T _C1 , T _C2
and T _C3 are the second information signals. 1st and 2nd
A signal containing at least a frequency division multiplexed signal consisting of the first and second FM color difference signals obtained by frequency modulating the color difference signals of ) recorded tracks, each of which is formed at an angle with respect to the longitudinal direction of the tape. truck
T _Y1 and T _C1 are the first rotary head H _M1 and the third rotary head, which will be described later.
The tracks T C2 and T Y2 are formed separately and simultaneously by the second rotary head H _S1 and the second rotary head H _S1 via the wide guard band G1, and during the next field period, the tracks T _C2 and T _Y2 are formed by the second rotary head H _S2 and the first 4 rotating heads
_HM2 separately and simultaneously through a wide guard band _G2 . Furthermore, in the next one field period, tracks T _Y3 and T _C3 are formed by the rotary heads H _M1 and H _S1 separately and simultaneously via a wide guard band _G3 . Also,
No guard band is formed (or a very small guard band is formed) between tracks T _Y2 and T _Y3 and between T _C1 and T _C2 .

In Fig. 4, the rotary heads H _M1 and H _S1 are connected to the track T _Y1 ,
When reaching the end of T _C1 , the rotating heads H _S2 and H _M2
This shows the situation when is located at the starting end of the next track T _C2 and T _Y2 . The FM luminance signals recorded on tracks T _Y2 and T _Y3 are recorded with their carrier frequencies different from each other by the frequency Δf, and the FM luminance signals recorded on tracks T _C1 and T _C2 are different from each other by the frequency Δf. The two FM color difference signals are recorded with their carrier frequencies different from each other by the frequency Δf.

When reproducing an already recorded signal on a magnetic tape with a track pattern recorded as described above, for example, when reproducing track T _Y2 , the carrier wave frequency of the FM signal reproduced as crosstalk from the adjacent track T _Y3 becomes an odd number of f _H /2. Since the carrier frequency of the FM signal of the original reproduction track _TY2 differs by the frequency Δf, the original reproduction track _TY2 and the adjacent track
In the case of still images, the frequency components of the lower sideband of each reproduced FM signal of T _Y3 differ by the above frequency Δf,
Beat disturbance due to crosstalk is visually significantly reduced.

Note that during the above reproduction, the DC level (pedestal level) of the reproduced luminance signal and reproduced color difference signal for each field oscillates up and down, which causes visual flicker as a change in the luminance level in two field cycles. In order to eliminate this, it is necessary to eliminate the above-mentioned DC level vibration. In a VTR, the head switching pulse has a completely phase synchronized relationship with the rotational phase of the rotary head, so the correspondence between the rotary head that recorded the carrier-shifted FM signal and the head switching pulse is determined during playback. Since the phase can be directly matched to the correspondence between the rotating head and the head switching pulse, it is possible to distinguish the recording track of the carrier-shifted FM signal, and thus the DC level vibration of the reproduced luminance signal and reproduced color difference signal mentioned above can be easily eliminated during reproduction. can be removed.

Note that the present invention is not limited to the above-mentioned embodiments, and for example, the gap of the rotary head H _M1 can be
The azimuth angle may be the same as that of H _S2 , and the gap of H _M2 may be the same azimuth angle as that of H _S1 (however, in this case, recording and playback that is compatible with current VTRs is not possible). 4 more rotating heads H _M1 ,
When recording two parallel tracks with all the heights of H _M2 , H _S1 , and H _S2 different, the following two are added to the guard band between the two parallel tracks recorded immediately before.
The present invention can also be applied to a recording method in which one of the parallel tracks of a book is positioned.

Effects of the Invention As described above, according to the present invention, adjacent information signal recording tracks of the same type are recorded with carrier wave frequencies of FM signals different from each other by an odd multiple of 1/2 of the horizontal scanning frequency _fH . As a result, the azimuth loss effect caused by crosstalk from adjacent tracks during playback cannot be obtained, and the low frequency components of the lower sideband of the FM signal can also be made to differ by an odd multiple of f _H /2. As a result, it is possible to visually significantly reduce beat interference due to crosstalk, especially in the edge image area where the lower sideband is greatly expanded, and compared to the conventional Y/C separation recording method. The present applicant was the first to discover that magnetic tape is highly efficient and that it is possible to form track patterns that can be played back compatiblely with current home VTRs with an inexpensive configuration without using a tracking control mechanism (AST). While making full use of the features of the recording method proposed in 2003, it has the advantage of being able to reproduce particularly brightness signals and color difference signals with good S/N, and recording that produces high-quality reproduced color images. be.

BRIEF DESCRIPTION OF THE INVENTION Fig. 1 is a block system diagram showing one embodiment of the present invention, and Fig. 2 is a diagram showing an example of the arrangement relationship of the rotary head, etc., previously proposed by the applicant, which can be applied to the present invention. , FIGS. 3A and 3B are views showing an example of the arrangement relationship between two rotating heads that are close to each other, and FIG. 4 is an example of a track pattern previously proposed by the applicant that can be applied to the method of the present invention. Figures 5 and 6 show the FM luminance signal and FM luminance signal recorded by the present invention, respectively.
A diagram showing an example of a frequency spectrum of a color difference signal,
FIG. 7 is a diagram showing an example of an image, and FIG. 8 is a diagram explaining an example of the relationship between the carrier frequency of the FM signal and the frequency component of the lower sideband.

DESCRIPTION OF SYMBOLS 1... Color video signal input terminal, 3... Comb filter, 8, 20, 21, 28... Addition circuit, 9... Head switching pulse input terminal, 11, 24,
25...FM modulator, 29...magnetic tape, H _M1 ...first rotating head, H _S2 ... second rotating head, H _S1
...Third rotating head, H _M2 ...Fourth rotating head.

Claims (1)

[Scope of Claims] 1. First and second rotating heads mounted at opposite positions on the rotating surface of a rotating body around which a running magnetic tape is wound over a predetermined angle range; and the rotating body. are mounted at opposing positions on the rotating surface of the rotating body, and are respectively close to the mounting positions of the first and second rotating heads in the rotational direction of the rotating body, and Of the third and fourth rotary heads installed at different heights in the axial direction, the frequency modulated luminance signal is transmitted to the first and fourth rotary heads having gaps of different azimuth angles. At the same time, two types of color difference signals in predetermined signal formats are supplied to the second and third rotary heads having different azimuth angle gaps, and during one track scanning period, the first and third rotary heads are The third rotary head allows the first one to have a wide guard band between each other.
and a second track separately and simultaneously, and during the next one track scan period, the second and fourth rotating heads form third and fourth tracks having a wide guard band between each other. the frequency modulated luminance signal and the two
Two parallel tracks in which different color difference signals are recorded separately are sequentially formed, and a difference between adjacent frequency modulated luminance signal recording tracks recorded and formed by the first and fourth rotary heads and the second parallel track is formed. A magnetic recording method in which recording is performed with very small or no guard bands provided between adjacent color difference signal recording tracks recorded by the second and third rotating heads, the first The frequency of the difference between the carrier frequency of the frequency modulated luminance signal recorded by the rotating head and the carrier frequency of the frequency modulated luminance signal recorded by the fourth rotating head is defined as f _H /2 (where f A magnetic recording method characterized in that the frequency-modulated luminance signal is recorded by selecting a frequency that is an odd multiple of a horizontal scanning frequency ( _H is a horizontal scanning frequency). 2 The two types of color difference signals in the predetermined signal format are first and second carrier waves obtained by separately frequency modulating first and second carrier waves of different frequencies with the two types of color difference signals. A frequency division multiplexed signal consisting of a frequency-modulated color difference signal, in which the frequencies of both the first and second carrier waves are changed every one track scanning period.
2. The magnetic recording method according to claim 1, wherein recording is performed by switching to have a frequency difference that is an odd multiple of f _H /2.