JPH0828883B2 - Magnetic recording / reproducing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image such as a current NTSC system having a screen aspect ratio of 4: 3 and an EDTV system or a high-definition system which is a landscape TV system having a screen aspect ratio of 16: 9. The present invention relates to a magnetic recording / reproducing apparatus such as a video tape recorder for recording and reproducing a signal on a magnetic tape.

[0002]

2. Description of the Related Art Conventionally, VHSs such as VHS and 8 mm have been widely used in homes as video tape recorders (hereinafter abbreviated as VTRs) for recording color video signals. In particular, VHS type VTRs have spread to over 250 million units all over the world, and are one of the necessities for general households. In these VTRs,
For example, an input NTSC color video signal is separated into a luminance signal and a carrier color signal, the luminance signal is frequency-modulated with a low carrier, and the carrier color signal is low-frequency converted and recorded on a magnetic tape. The recording / reproducing system is, for example, by Yokoyama,
"Home Video Technology", edited by Japan Broadcast Publishing Association and written by Sugaya,
SMPTE Journal, March 1986, pages 301-309.

[0003]

However, in these conventional VTRs, since the color signal is converted into the low frequency band and recorded, the band of the reproduced color signal and the SN ratio are the same as the band and the SN ratio of the reproduced luminance signal. In comparison, it is unbalanced, and the color signal limits the reproduced image quality. In particular, when the luminance signal is made into a high band to have high quality as in the SVHS-VTR and Hi-8-VTR, the quality difference between the color signal and the luminance signal is further widened.

In view of the above points, the present invention is a conventional home-use V
It is an object of the present invention to provide a magnetic recording / reproducing apparatus which records / reproduces a color signal having a higher SN than TR and a wide band.

[0005]

In order to solve the above problems, according to the present invention, two tracks in which a conventional color video signal is recorded in one frame period (one rotation period of a rotary cylinder) of a video signal. In the meantime, one new track is newly formed, and a signal obtained by frequency-modulating the color signal is recorded by another head.

At the time of reproduction, for example, if the FM-modulated new color signal is reproduced in the half rotation period of the rotary cylinder, the conventional luminance signal and new color signal are output, and the FM signal is output.
If the modulated new color signal is not reproduced, the conventional luminance signal and the conventional low-frequency conversion color signal are output. Therefore, there is no need to make any changes to the conventional VTR, and the signal compatibility between the VTR of the new recording system and the VTR of the conventional recording system can be ensured. Further, this system is characterized in that the conventional low-frequency conversion color signal can be used even when the FM-modulated color signal is not reproduced at the time of special reproduction.

[0007]

The present invention has the above-described structure and is used for conventional home-use V
It becomes possible to reproduce a high-quality color signal having a wider SN ratio and a wider band than TR. Moreover, even if the magnetic tape recorded by this method is reproduced by the conventional VTR, since the conventional low-frequency conversion color signal is recorded, compatibility with the conventional VTR can be ensured.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of essential parts of a magnetic recording / reproducing apparatus according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a first color video signal.
The NTSC composite video signal is inputted from here to the input terminal of and the Y / C separation circuit 2 separates it into a luminance signal Y and a carrier color signal C. Reference numeral 3 denotes a second input terminal pair for the color video signal, from which the luminance signal Y and the carrier color signal C of the components forming the NTSC video signal are input. Y
The Y and C signals from the / C separation circuit 2 and the input terminal pair 3 are switched to arbitrary input signals by the switcher circuit 4.

The output Y of the switcher circuit 4 is FM-modulated in the one-field memory circuit 5 after being delayed by one field period of the video signal, and then subjected to linear or non-linear emphasis in the FM modulation circuit system 6. . The output C of the switcher circuit 4 is input to the low frequency conversion circuit 7, frequency-converted to a frequency lower than the FM-modulated Y signal, and then added to the FM-modulated Y signal in the adder circuit 8, It reaches the recording amplifier 9.

The output C of the switcher circuit 4 is further supplied to the demodulation circuit 10 as two baseband color difference signals (RY).
And (BY) are demodulated and input to the pre-filter circuit 11. As an example, the pre-filter circuit 11 is configured by three cascaded 1-line (1H) delay circuits and a multiplication circuit (not shown) that multiplies the output of each 1H delay circuit by a tap coefficient, The tap coefficient of the first and third 1H delay circuits is 0.25, and the tap coefficient of the second 1H delay circuit is 0.5. Inside the pre-filter circuit 11, two color difference signals, which are addition outputs of these three multiplication circuits, are 1H (1H
= 1 horizontal synchronization period length) The switcher circuit 12 can switch the output for each horizontal synchronization period length.

So-called color signals are converted into line-sequential signals from which aliasing distortion has been removed. The color difference signal output of one system of the pre-filter circuit 11 is input to the switching circuit 12, and the output is turned on / off every half rotation period of the rotating cylinder. Next, the signal is input to the FM modulation circuit 13, subjected to linear or non-linear emphasis, and then FM-modulated,
It reaches the recording amplifier 14.

As described above, in this embodiment, the field skipped line-sequential color difference signal is FM recorded as a new recording signal. If 1 MHz is secured as the baseband band of this field-skipped line-sequential color difference signal,
The image quality is more excellent than the image quality of the conventional low-frequency conversion carrier color signal, and is necessary and sufficient for home use from the viewpoint of human visual characteristics.

Here, in FIG. 1, 15 is a rotating cylinder, 16 is the rotating direction thereof, 17 is a magnetic tape, 1
8 is the traveling direction. Also, 19, 20 and 21
Are magnetic heads and have different azimuth angles. The magnetic tape 17 has about 180 rotation cylinders.
Each of the three magnetic heads is a so-called helical scan type VTR that is wound around the magnetic tape 17 at an angle.

The output of the above-mentioned recording amplifier 9 is passed through a well-known rotary transformer to two magnetic heads 19 and 20 arranged on the circumference of the rotary cylinder 15 so as to be symmetrical to each other by about 180 degrees. Then, the first and second signal recording tracks are formed on the magnetic tape 17. Further, the output of the recording amplifier 14 described above is guided to the magnetic head 21 and forms a third signal recording track on the magnetic tape 17.

The output of the recording amplifier 9 is the head 1
The recording current values of 9 and 20 are set to a recording level at which the reproduction output from the magnetic tape is almost maximum, that is, a so-called saturated recording level. On the other hand, the output of the recording amplifier 14 is set to a recording level at which the recording current value of the head 21 is slightly lower than the recording level at which the reproduction output from the magnetic tape is maximum. Since the recording level of the head 21 is lower than the supersaturated recording level, even if the third signal recording track overlaps the first signal recording track, the first signal is not completely erased, and the first signal is recorded on the third signal track. It is possible to leave the signal of.

That is, in this embodiment, the conventional FM luminance signal and the low-frequency conversion color signal are recorded and reproduced using two tracks for each revolution of the rotary cylinder, and further, the conventional low-frequency conversion color signal is further reproduced. It is also possible to record and reproduce a high quality color signal by using one newly formed track.

FIG. 2 shows an example of the recording track pattern. Here, the case where the present invention is applied to the long-time recording mode of the VHS system VTR will be described. In this case, the magnetic tape is driven by the capstan motor to move by 19.3 μm during the half rotation of the rotary cylinder. The head track width and azimuth angle of the magnetic heads 19 and 21 are 26 micrometer and +6, respectively.
And 18 micron meter and -15 degrees. Also,
The head track width and azimuth angle of the magnetic head 20 are set to 26 microns and -6 degrees.

In FIG. 2, T1 (+6), T1 (-
6) are tracks recorded by the magnetic heads 19 and 20, respectively, and T2 (−15) is a track recorded by the magnetic head 21. Also, T1
The recording track widths of (+6) and T1 (-6) are 15.3
The recording track width of the micron meter and T2 (-15) is 8 micron meter. The azimuth angle of the magnetic head 21 is not particularly limited to the angle in the above example, and may be any angle as long as a high SN ratio or a desired frequency characteristic is obtained in relation to other magnetic heads.

FIG. 3 is an explanatory view of the principle of the track pattern formation of FIG. In FIG. 3, in order to leave a recording track by the magnetic head 21 of 8 μm, the relative height of the lower end of the magnetic head 19 is lowered by 4 μm from the relative height of the lower end of the magnetic head 20.
By shifting the relative heights of the lower ends of the two magnetic heads facing each other by 180 degrees, it is possible to make the recording track widths of the magnetic head 19 and the magnetic head 20 equal while securing a new track by the magnetic head 21.

FIG. 4 shows an example of frequency arrangement of this recording method. FIG. 4A shows a case where this embodiment is applied to a VHS system VTR. FM luminance signal is about 1MHz to about 6M
It is used in the band of Hz, and no signal is recorded in the band of 6 MHz or higher. Here, 5MHz to 7M
FM color signals are recorded and reproduced in the Hz band. A CN ratio of the reproduced carrier of about 35 dB (noise band of 30 kHz) is sufficient for good recording and reproduction of the FM color signal.
According to the experiments by the present inventors, when the magnetic tape for VHS is used, the recording track width is 8 μm and the recording track width is 7 M.
It has been confirmed that it is possible to secure a CN ratio in the vicinity of Hz of 35 dB or more. Also, FM luminance signal and FM
Even if the bands of color signals overlap, crosstalk interference can be removed by the azimuth loss effect between recording tracks. Here, the recording band of the FM color signal is 5
Although the frequency is changed from 7 MHz to 7 MHz, the FM luminance signal and the F
Band sharing is possible for the M color signal.

As in the case of the VHS system, FIG.
Shows the case where this embodiment is applied to the SVHS system VTR. The FM luminance signal is used in the band of about 1 MHz to about 10 MHz, and no signal is recorded in the band of 10 MHz or higher. Here, the FM color signal is recorded and reproduced in the band from 9 MHz to 11 MHz. Here, the recording band of the FM color signal is changed from 9 MHz to 11 MHz, but 2
Even in the band from 4 MHz to 4 MHz, the band can be shared between the FM luminance signal and the FM chrominance signal by utilizing the azimuth loss effect even in the case of 5 MHz to 7 MHz which is the same as in the VHS system VTR.

During reproduction, the two magnetic heads 19
And the outputs of 20 are passed through a rotary transformer.
It is amplified by the reproducing head amplifier 22. Similarly, the outputs of the two magnetic heads 21 are also amplified by the reproducing head amplifier 28 through the rotary transformer.

The output of the head amplifier 22 reaches the BPF 23, where only the FM luminance signal is extracted, demodulated into a baseband signal by the FM demodulation circuit system 24, and then deemphasized. The output of the FM demodulation circuit system 24 is delayed by one field period in the one field memory circuit 25.

The output of the head amplifier 22 is the BPF.
At 26, the low-frequency-converted carrier color signal is extracted and converted to the original NTSC signal frequency by the frequency conversion circuit 27. 1-field delay circuit 28
Is delayed by one field period and then input to the switcher circuit 35.

The output of the head amplifier 29 reaches the BPF 30, where the FM color signal is extracted, and the FM demodulation circuit system 3
After being demodulated to a baseband signal at 1, de-emphasis processing is performed. Further, the output of the FM demodulation circuit system 31 is input to the field memory 32, and the period in which the FM color signal does not exist is replaced with the signal in the period in which the FM color signal exists and is output. The output signal of the field memory 32 is input to the post-filter circuit 33, subjected to the same signal processing as that performed by the pre-filter circuit 11, and a set of (RY) signal and (BY) signal. And after being restored to
The quadrature two-layer modulation circuit 34 performs quadrature modulation on the quadrature and forms a carrier color signal which is input to the switcher circuit 35.

Now, the FM demodulation circuit system 31 determines whether or not the FM color signal is recorded during the half rotation period of one rotation period of the cylinder. As a result of the determination,
If the FM color signal is not reproduced, the output from the frequency conversion circuit 27 is selected as the output of the switcher circuit 35. Further, as a result of the determination, when the FM color signal is reproduced, the output of the quadrature two-layer modulation circuit 34 is selected as the output of the switcher circuit 35.

Next, the reproduction luminance signal Y which is the output of the 1-field memory circuit 25 and the reproduced carrier color signal C which is the output of the switcher 35 are added by the adding circuit 36 and output from the output terminal 37. In addition, the reproduction luminance signal Y output from the 1-field memory circuit 25 and the switcher circuit 35.
The reproduced carrier color signal C, which is the output of the above, is output from the output terminal 38 as a component signal.

The tape recorded by the VTR of this embodiment is recorded as VH.
Even if it is played back on an S-type or SVHS-type VTR, VH
Since the S system or SVHS system VTR signal is recorded, there is no problem in reproducing the color video signal.

In this embodiment, the case where the field skipped line-sequential color difference signal is FM-recorded has been described as an example of the signal recorded between the conventional color video signal tracks. Alternatively, it is possible to use a time-axis expansion / compression (TCI) system color signal adopted in the MII system VTR used for broadcasting or business. Further, as an example of the signal recorded between the color video signal tracks, the same effect can be obtained by a digitally modulated color signal or luminance signal, or a signal obtained by digitally modulating the luminance signal and the color signal.

Further, it is possible to record / reproduce an audio signal other than a video signal, an index signal, or a signal obtained by analog or digitally modulating a control signal. As described above, the same effect can be obtained even in the case of an analog signal or a digital signal in which all information is modulated as a signal to be recorded overlaid on a color video signal track.

[0032]

As described above, the present invention relates to a VTR which records and reproduces a color video signal, and frequency-modulates a field-skip line-sequential color difference signal to separate the tracks on which the conventional color video signal is recorded. Record with the head. By doing so, compared to the conventional home VTR,
It becomes possible to reproduce a high-quality color signal in a wide band with a higher SN ratio. Moreover, since the conventional low-frequency conversion color signal is recorded even when the magnetic tape recorded by the method of the present invention is reproduced by the conventional VTR, compatibility with the conventional VTR can be ensured during reproduction. is there.

[Brief description of drawings]

FIG. 1A is a block diagram of an essential part of a recording system of a magnetic recording / reproducing apparatus according to an embodiment of the present invention. FIG. 1B is a block diagram of an essential part of a reproducing system of a magnetic recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a recording track pattern diagram in one embodiment of the present invention.

3 is an explanatory diagram of a method of forming the recording track pattern of FIG.

FIG. 4A is a characteristic diagram showing a frequency arrangement of recording signals when the VHS system is applied. FIG. 4B is a characteristic diagram showing a frequency arrangement of recording signals when the SVHS system is applied.

[Explanation of symbols]

 1 composite color video signal input terminal 2 Y / C separation circuit 3 component color video signal input terminal 4 switcher circuit 5 1 field memory circuit 6 FM modulation circuit system 7 low frequency conversion circuit 8 adder circuit 9 recording amplifier 10 demodulation circuit 11 pre Filter circuit 12 Switcher circuit 13 FM modulation circuit system 14 Recording amplifier 15 Rotating cylinder 16 Rotating direction of rotating cylinder 17 Magnetic tape 18 Magnetic tape advancing direction 19, 20, 21 Magnetic head 22 Playback head amplifier 23 BPF 24 FM demodulation circuit system 25 1 Field memory circuit 26 BPF 27 Frequency conversion circuit 28 1 field memory circuit 29 Playback head amplifier 30 BPF 31 FM demodulation circuit system 32 Field memory circuit 33 Post filter circuit 34 Right angle two-layer modulation circuit 35 Switcher circuit 6 the adder circuit 37 the composite color video signal output terminal 38 component color video signal output terminal

Claims (6)

[Claims] 1. A conversion circuit for converting an input color video signal into a luminance signal, a carrier color signal, and two color difference signals, and a first frequency modulation circuit for frequency-modulating the luminance signal output from the conversion circuit. A low frequency conversion circuit for low frequency converting the carrier color signal output from the conversion circuit, a second frequency modulation circuit for frequency modulating the color difference signal output from the conversion circuit, and the low frequency converted carrier An adder circuit for adding a color signal and a frequency-modulated luminance signal, a first magnetic head pair for recording and reproducing a color video signal output from the adder circuit on a magnetic recording medium, and the first magnetic head. A magnetic recording / reproducing apparatus comprising: a second magnetic head for recording and reproducing a frequency-modulated color signal which is an output of the second frequency modulation circuit between two tracks to be recorded by a pair. 2. A pre-filter circuit composed of a line memory and a switching circuit for sequentially switching two color difference signals for each horizontal synchronizing period of a color video signal during recording and inputting them to a second frequency modulation circuit, Further, at the time of reproduction, there is provided a post filter circuit configured by a complementary circuit that complements the color difference signal that is switched and reproduced every one horizontal synchronization period and outputs two color difference signals every one horizontal synchronization period. The magnetic recording / reproducing apparatus according to claim 1. 3. A frequency-modulated luminance signal reproduced by the first magnetic head pair is frequency-demodulated when the frequency-modulated color signal is reproduced by the second magnetic head during reproduction for about half a rotation period of the rotary cylinder. The sum of the luminance signal and the color signal obtained by frequency demodulating the frequency-modulated color signal recorded by the second magnetic head and passing through the post-filter circuit. Is output as a reproduced color video signal, and when the frequency-modulated color signal is not reproduced by the second magnetic head during reproduction, a frequency-modulated luminance signal reproduced by the first magnetic head is used as a luminance signal. The low-frequency-converted carrier color signal is added by the adder circuit to a carrier color signal that has been frequency-converted into a carrier color signal in the same frequency band as the input, Magnetic recording and reproducing apparatus according to claim 1, wherein outputting the output of the calculation circuit as the reproduced color video signal. 4. A first pair of magnetic heads are arranged on a rotating cylinder symmetrically about 180 degrees, and the two azimuth angles are two magnetic heads having an inverse azimuth relationship with each other, and The magnetic head is arranged between the first magnetic head pair on the rotary cylinder, and the azimuth angle of the magnetic head is one magnetic head having an azimuth angle different from the azimuth angle of the first magnetic head pair. The magnetic recording / reproducing apparatus according to claim 1, wherein 5. A delay circuit for delaying the luminance signal by one field period of the luminance signal before being FM-modulated at the time of recording or after being FM-demodulated at the time of reproducing. The magnetic recording / reproducing apparatus according to claim 1. 6. A conversion circuit for converting an input color video signal into a luminance signal, a carrier color signal, and two color difference signals, and a first frequency modulation circuit for frequency-modulating the luminance signal output from the conversion circuit. A low-pass conversion circuit for low-pass converting the carrier color signal output from the conversion circuit, a digital modulation circuit for digitally modulating the color difference signal output from the conversion circuit, and the low-pass converted carrier color signal, An adder circuit for adding the frequency-modulated luminance signal, a first magnetic head pair for recording and reproducing a color video signal output from the adder circuit on a magnetic recording medium, and recording by the first magnetic head pair. And a second magnetic head for recording and reproducing the color signal, which is the digital modulation circuit, between the two tracks.