JPS59162602A - Picture recording and reproducing device - Google Patents

Abstract

PURPOSE:To increase signal components of an analog signal such as a low band conversion chroma signal or the like by recording the analog signal of both recording layers of a magnetic recording medium having a double structure and adding both signals at a reproducing time. CONSTITUTION:Luminance signal components are subjected to FM modulation by an FM modulator 7 and are supplied to a pulse width modulator 8. A chroma signal is converted to a low band by a low-band converter 10. This output has only a band signal extracted by an LPF 11. The output of the pulse width modulator 8 has a low-band side band eliminated by an HPF 12. The output of a mixer 13 is amplified and is recorded onto a magnetic tape 17 having a double structure. The reproduced signal has only FM wave signal components extracted by an HPF 19 to demodulate the luminance signal in a demodulator 20 through one route and has only the low band conversion chroma signal separated by an LPF 22 through the other. This output includes a low-band conversion chroma signal from a horizontal magnetized recording layer and chroma signal components from a vertical magnetized recording layer. This output is converted to a chroma signal by a high-band converter 23. Thus, two chroma signals are added to increase sufficiently signal components.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises a magnetic material in the form of a tape or sheet, in which a perpendicular magnetic recording layer that forms residual magnetization in the thickness direction and a horizontal magnetic recording layer that forms residual magnetization in the longitudinal direction of the magnetic material are stacked. Regarding an image recording and reproducing device that multiplexes image information, etc. on a magnetic recording medium having a combined two-layer structure and reproduces the same,
In particular, the present invention relates to a means for effectively recording and reproducing an analog signal, which is multiplexed with an FM wave subjected to FM modulation on a luminance signal, on a magnetic recording medium.

In recent years, so-called perpendicular magnetic recording, which forms residual magnetization in the thickness direction of a magnetic recording medium, has been attracting attention as a means of high-density recording.

The magnetic recording media used in this perpendicular magnetic recording method include:
It is required to have a rectangular shape that has perpendicular magnetic anisotropy and whose hysteresis characteristics are as sharp as possible. When residual magnetization is formed in such a magnetic recording medium, positive or negative residual magnetization that has reached a saturation value is stably formed. On the other hand, it is extremely difficult to maintain residual magnetization in a state between positive and negative. In the horizontal magnetic recording method, which is a conventional general magnetic recording method, that is, the magnetic recording method that forms residual magnetization in the longitudinal direction (horizontal direction) of the magnetic recording medium, analog signals are made linear by using an alternating current bias on the recording medium. It is well known that it can be recorded well. However, it is extremely difficult to record analog signals with good linearity even when AC bias is used on a perpendicular magnetic recording medium having perpendicular magnetic anisotropy as described above. This is explained in the literature IWASAKI;
IEEE TRANS.

MAG-16, No, IJ entry N 1980 PP7
1 to 76 are also described in detail. As described above, the recording medium used for perpendicular magnetization type recording is a very advantageous recording medium for recording and reproducing digital signals, but it can be said that it is a very disadvantageous recording medium for analog signals. By the way, when recording and reproducing video signals, it is common to record and reproduce 4FM waves that are F-M modulated by the luminance signal included in the video signal, but in this case, audio signals and low-frequency converted colors are If signals and the like are recorded and reproduced by multiplexing them into FM waves, the usage efficiency of the recording medium should be further improved. It is well known that FM waves are treated as digital signals, but if an audio signal or a low-frequency converted color signal is multiplexed onto the FM waves, analog signals will be mixed in the FM waves.

Therefore, it is impossible to multiplex record this signal on the above-mentioned perpendicular magnetic recording medium having perpendicular magnetic anisotropy. In order to make this multiplex recording possible, in recent years, perpendicular magnetic recording media and horizontal magnetic recording layers have been developed.

FIG. 1 conceptually depicts one example. In FIG. 1, -1 is a perpendicular magnetic recording layer, 2 is a horizontal magnetic recording layer, 3 is a base layer made of Mylar or polyester, and 4 is a recording/reproducing head. The magnetic field generated by the recording signal generated by the recording/reproducing head 4 is recorded and formed in both recording layers 1.degree.2 as residual magnetization. In this case, the perpendicular magnetic recording layer l has positive and negative poles (N poles) in the thickness direction.

A remanent magnetization of S-polarity is formed. Note that since no residual magnetization is formed in this perpendicular magnetic recording layer 1 in the longitudinal direction, high-density recording can be performed. In particular, signals in the short wavelength region are efficiently recorded. On the other hand, residual magnetization is formed in the horizontal magnetic recording layer 2 in the longitudinal direction. In this case, signals in the short wavelength region, that is, high frequency signals, are attenuated greatly and are hardly recorded, whereas signals in the long wavelength region are mainly recorded efficiently.

However, when the above two-layered recording medium is used, the following problems remain to be solved. In other words, when recording multiplexed analog signals as well as digital signals on a recording medium having a two-layer structure, the analog signals in the long wavelength region are recorded on the horizontal magnetic recording layer 2 located far from the head 4. The problem was that the level was likely to be insufficient and it was difficult to obtain a reproduced analog output with a sufficiently large S/>T ratio.

An object of the present invention is to efficiently multiplex record and reproduce image information, etc., on a magnetic recording medium having a two-layer structure in which a perpendicular magnetic recording layer and a horizontal magnetic recording layer are superimposed, and in particular to record and reproduce image information, etc. It is an object of the present invention to provide an image recording and reproducing device capable of recording and reproducing analog signal components with a sufficiently large S/N ratio.

In order to achieve the above object, the present invention is characterized by the following configuration. That is, during recording, after obtaining an FM wave that is FM modulated by the luminance signal of the video signal to be recorded, this FM wave is converted into a signal obtained by converting an analog signal such as a chroma signal included in the video signal into a low-frequency signal. This pulse width modulated signal is magnetically recorded on the perpendicular magnetic recording layer of a two-layer recording medium, and the analog signal such as the low frequency converted chroma signal is recorded in the two-layer structure. When magnetically recording on the horizontal magnetic recording layer of a medium, during reproduction, an analog signal such as a low frequency converted chroma signal reproduced from the vertical magnetic recording layer and an analog signal such as a low frequency converted chroma signal reproduced from the horizontal magnetic recording layer. and obtain a reproduced analog signal such as a reproduced chroma signal. In this way, an analog signal such as a low frequency converted chroma signal is recorded not only in the horizontal magnetic recording layer but also in the vertical magnetic recording layer, and by adding both signals during playback, the signal component of the analog signal can be increased. It is characterized by being able to be measured.

Hereinafter, details of the present invention will be made clear by referring to embodiments shown in the drawings.

FIG. 2 is a block diagram showing the electrical configuration of an embodiment of the present invention. First, recording system A will be explained. Input terminal 5
The luminance signal component contained in the signal to be recorded, that is, the video signal, given to the LPF 6 is separated and extracted, subjected to FM modulation by the frequency modulator 7, and then supplied to the pulse width modulator 8.

On the other hand, a chroma signal (carrier color signal) of 3.58 MH2±500 KHz included in the video signal is separated and extracted by the BPF 9, and converted into a low frequency converted chroma signal. Note that the low frequency converter 10 is a VH8 system used in a well-known VTR, β
It is sufficient to adopt a low-frequency conversion method such as the above method. Low frequency converter 1
The output of 0 is 629'KHz +:50 to LPFll.
Only the 0 KHz band signal is extracted and supplied to the pulse width modulator 8 as a modulation input.

The output of the pulse width modulator 8 is supplied to the HPF 12 and converted into FM
After the low-frequency sideband of wave ′ has been removed, mixer 1
This is one input of 3. The reason why the low frequency sideband is removed by the HPF I 2 is to superimpose the low frequency converted chroma signal on this part without causing beat interference with the FM wave.O As the other input of the mixer 13 The output of the LPF 11, that is, the low frequency converted chroma signal is supplied, and the HPFJ
It is superimposed on the FM wave which is the output of 2.

The output of the mixer 13 is current-amplified by the recording amplifier 14, and then supplied to the recording/reproducing head 16 via the recording side terminal lea of the recording/reproducing selector switch 15. It is recorded on the magnetic layer of a certain magnetic tape 17.

In FIG. 2, the state in which the pulse width modulator 8 is passed through is the conventional recording method such as the VH8 method or the β method. In other words, the main structural feature of this apparatus is that the pulse width modulator 8 is added to the conventional recording method described above. In the conventional system, the low frequency converted chroma signal superimposed on the FM wave by the mixer 13 is recorded only on the horizontal magnetic recording layer of the magnetic tape 17 as an analog signal. In this case, the FM wave is generally recorded at the recording current at the saturation level, whereas the low-frequency converted chroma signal is -15 dB to -20 dB below the saturation level.
only recorded at low levels. That is, the FM wave acts as a bias signal for the low frequency converted chroma signal. FIG. 3 is a diagram showing a specific configuration of the pulse width modulator 8. As shown in FIG. 3, the FM wave from the FM modulator 7 applied to the terminal 31 is supplied to the base of the PNP transistor 330 via the resistor 32, and is also supplied to the base of the NPN transistor 350 via the resistor 34. supplied to Positive and negative voltages +V and -V are applied to each emitter of the transistor 33 and 35, respectively. Therefore, when a square wave FM wave as shown in FIG. 481 is supplied to the base of each transistor 33.
When the wave is at +V level, transistor 33 is turned off and transistor 35 is turned on. Also, is it an FM wave?
When the level is high, the transistor 33 is turned on and the transistor 35 is turned off.

When the transistor 33 turns off, the transistor 3
The electric charge of the capacitor 36, which was charged to +V (■e) state when 3 was ON, is transferred to the resistor 37 and the constant current circuit 38.
Discharges in the direction of the arrow through -E(e■)
charged back to the state. In this case, charging and discharging are performed as shown in FIG. 82 at a time constant determined by the current set by the constant current circuit 38 and the value of the capacitor 36.

When the transistor 35 becomes QFF, the electric charge of the capacitor 39, which had been charged to the same state, is transferred to the resistor 40. Discharge occurs in the direction of the arrow through the constant current circuit 41, and then 10E (■○)
charged back to the state. In this case as well, charging and discharging are performed as shown in FIG. 483 using a time constant determined by the current set by the constant current circuit 41 and the value of the capacitor 39.

The charging and discharging currents of the capacitors 36 and 39 are respectively amplified by current amplifiers 42 and 43 which are buffers, and then supplied to a mixer 46 via a diode 44 and 45, and the mixed output of the mixer 46 is When the outputs of the current amplifiers 42 and 43 are mixed at a ratio of 1:1, a trapezoidal wave as shown at 84 in FIG. 4 vibrates in the positive and negative directions with the same amplitude around the ICO volt. The output of the mixer 46 is the voltage comparator 4
The signal from the LPF 11 applied to the terminal 48, that is, the low-frequency converted chroma signal, is supplied as the other input of the zero voltage comparator 47 which serves as one input of the 0 voltage comparator 47. This low-frequency converted chroma signal is a signal that oscillates sinusoidally in the positive and negative directions around 0 volts, as shown by the broken line in FIG. , so-called cerasoid modulation is performed.

As a result, the voltage comparator 47 outputs a signal whose pulse width W is modulated as shown in FIG.

In this way, the pulse width modulator 8 transmits the FM wave that has been subjected to FM modulation to the luminance signal included in the video signal to be recorded.
Further, the low-frequency converted chroma signal is modulated by elipulse width (duty ratio).

The output of the pulse width modulator 8 is the HPF
After removing frequency components (for example, 1.5 MHz or less) corresponding to the band of the low-frequency converted chroma signal at J2, the signal is supplied as one input of the mixer 13, on which the low-frequency converted chroma signal is superimposed. Ru.

86 in FIG. 5 shows the output waveform of HPF 12, and 87 in FIG.
is the output of LPFII, that is, the waveform of the low frequency converted chroma signal, and S8 is the output of the mixer 13, that is, the waveform of the above-mentioned S6 and 8.
This is the waveform of a signal mixed with 7. The signal of S8 is amplified and recorded on the magnetic tape 17. In this case, 5 cases
The FM wave signal component S6 shown in FIG. iR5 is dominantly recorded on the perpendicular magnetic recording layer 1 shown in FIG. Further, the low frequency converted chroma signal component S7 shown in FIG. 5 is dominantly recorded on the horizontal magnetic recording layer 2 shown in FIG. Here 1
Since the FM wave signal component S6 is modulated in the pulse width W by the low frequency converted chroma signal as described above, the low frequency converted chroma information is also recorded on the perpendicular magnetic recording layer I. As a result, compared to the conventional button in which the low-frequency converted chroma signal is recorded only in the horizontal magnetic recording layer 2, when the low-frequency converted chroma signal reproduced from both the horizontal and vertical magnetic recording layers is added during playback, the signal is The components increase and the noise level decreases relatively.

As shown in FIG. 2, the reproduction system B is constructed as follows. The signal reproduced from the magnetic tape 17 by the recording/reproducing head 16 is supplied to the voltage amplifier 18 via the reproducing side terminal 15b of the recording/reproducing changeover switch 15 and is voltage amplified. The output of the voltage amplifier 18 has a cut-off frequency of 1.5 on the one hand.
After the low frequency converted chroma signal component is removed by the MHz HPF19 and only the FM wave signal component is extracted,
The luminance signal is demodulated by the demodulator 29 and becomes one input of the mixer 21 .

On the other hand, the output of the voltage amplifier 18 is sent to an LPF 22 with a cutoff frequency of 1.5 MHz, where only 9 of the low frequency converted chroma signals (1.5 MHz±500 KHz) are separated and extracted. The output of the LPF 22 includes a low frequency converted chroma signal component reproduced from the vertical magnetic recording layer 1 as well as a low frequency converted chroma signal reproduced from the horizontal magnetic recording layer 2 . The output of the LPF 22 is converted by a high frequency converter 23 into a chroma signal in a band of 3.5 Mu z±500 KHz. This chroma signal is thus knee v-t
Since the r chroma signal is added, the signal component is sufficiently large, resulting in a high-quality reproduced chroma signal with a relatively low noise level. This chroma signal has a passband power r, $3
．． The Eris spurious component is removed by the BPF 24 of ssMaz±500KHz, and the signal becomes the other input of the mixer 2. Therefore, the brightness signal and the chroma signal are mixed by the mixer 21 to form a reproduced video signal, which is sent out from the output terminal 25.

FIG. 6 shows the frequency spectrum of the output J signal from the voltage amplifier 18. In FIG. 6, f is an FM carrier wave, and fz is a sideband generated by FM modulation. Furthermore, f is a low frequency converted chroma signal recorded on the horizontal magnetic recording layer, and f4 is a low frequency converted chroma signal recorded on the perpendicular magnetic recording layer. Since signals f and 14 have the same frequency, they are separated and extracted at the same time by the LPF 22 in FIG.

Note that the present invention is not limited to the above-mentioned embodiment. For example, in the embodiment described above, only a low frequency conversion chroma signal was shown as an analog signal for pulse modulating an FM wave, but
If necessary, an analog signal such as an audio signal may be subjected to elipulse modulation, and the analog signal may be recorded on the perpendicular magnetic recording layer 1. It goes without saying that other modifications may be made without departing from the gist of the present invention.

As explained above, according to the present invention, F
Barne width modulation is performed on the M-modulated FM wave using an analog signal such as a low frequency conversion chroma signal, and the analog signal is recorded not only in the horizontal magnetic recording layer of a two-layer magnetic recording medium but also in the vertical magnetic recording layer. By adding both signals during playback, the signal component of the analog signal is increased, so it is possible to efficiently multiplex record and play back image information, especially chroma signals, etc. It is possible to provide an image recording and reproducing device that can record and reproduce analog signal components of

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view schematically showing a two-layer magnetic recording medium in which a perpendicular magnetic recording layer and a horizontal magnetic recording layer are stacked, and FIGS. 2 to 6 show an embodiment of the present invention. In the figures, FIG. 2 is a block diagram showing the electrical configuration, FIG. 3 is a circuit diagram showing the specific configuration of the pulse width modulator, and FIG. 4 is a signal waveform of each part of FIG. 3. Figure, Figure 5 is HPFJ,? output signal and LPFI
FIG. 6 is a waveform diagram showing how the output signal of I is mixed. FIG. 6 is a diagram showing the frequency spectrum of the output signal of the voltage amplifier 18. 1... Perpendicular magnetic recording layer, 2... Horizontal magnetic recording layer, 3...
- Pace layer, 4... recording/reproducing head, 5... input terminal, 13. :ll...Mixer, 15...Recording/reproducing changeover switch, 16...Recording/reproducing head, 17...Magnetic tape, 25...Output terminal, 38.41...Constant current circuit, 47... voltage comparator. Applicant's Representative Patent Attorney Takehiko Suzue Figure 1 Figure 5 1 1 1 Figure 6 1 5L Support Procedures Amendment 1 October 238, 1980 Commissioner of the Japan Patent Office Kazuo Wakasugi ■ Patent application for indication of the case Relationship with Nagisa Ichi 1 Mari 1° with No. 1j113 of 1983 Patent applicant (037') Orin Gusu Optics T Gyo Co., Ltd. Reisha 4, Agent

Claims (1)

[Claims] A magnetic recording medium having a two-layer structure in which a perpendicular magnetic recording layer that forms residual magnetization in the thickness direction of a magnetic material and a horizontal magnetic recording layer that forms residual magnetization in the longitudinal direction of the magnetic material are superimposed, and this magnetic recording medium. means for obtaining an FM wave that is subjected to FM modulation on the luminance signal of a video signal to be recorded; and a low-frequency conversion signal of an analog signal such as a chroma signal included in the video signal by using the FM wave obtained by this means. means for magnetically recording the pulse width modulated signal on the perpendicular magnetic recording layer; and means for magnetically recording the analog signal such as the low frequency converted chroma signal on the horizontal magnetic recording layer. a means for recording, and adding an analog signal such as a low frequency converted chroma signal reproduced from the perpendicular magnetic recording layer and an analog signal such as a low frequency converted chroma signal reproduced from the horizontal magnetic recording layer during reproduction; 1. A magnetic recording and reproducing device comprising: means for obtaining a reproduced analog signal such as a reproduced chroma signal.