JPH06153229A - Color video signal magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To reproduce a broad band high definition color signal with high S/N by applying frequency modulation to a line sequential color difference signal with a time axis reference signal subject to field skip added thereto and recording the resulting signal on a new track between tracks with a color video signal recorded thereon by other head. CONSTITUTION:An NTS composite video signal inputted from an input terminal 1 is given to a Y/C separator circuit 2, in which the signal is separated into a luminance signal Y and a chrominance carrier signal C. The Y, C signals of the video signal component are inputted from an input terminal 3. Any of the Y, C signals inputted from the input terminals 3 is selected by a switcher circuit 4. An output Y of the circuit 4 is delayed by one field period at a memory circuit 5 and frequency-modulated by a modulation circuit 6. Furthermore, the output C of the circuit 4 is converted into a low frequency signal by a conversion circuit 7 and added to the Y signal at an adder circuit 8 and the sum is inputted to an amplifier 9. On the other hand, the output C of the circuit 4 is demodulated into color difference signals R-Y, B-Y by a demodulation circuit 10 and a line sequential color difference signal is inputted to an addition circuit 12 via a pre-filter circuit 11, a horizontal synchronizing signal of the signal Y from the circuit 4 is added and the video signal is recorded between tracks via a recording amplifier 14 and a modulation circuit 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to the current NTSC system, PAL system and S system having a screen aspect ratio of 4: 3.
Color such as a video tape recorder (abbreviated as VTR) that records and reproduces a color video signal such as ECAM system, EDTV system which is a landscape TV system with a screen aspect ratio of 16 to 9 or high definition system on a magnetic tape. The present invention relates to a video signal magnetic recording / reproducing apparatus.

[0002]

2. Description of the Related Art Conventionally, at home, a VHS such as a VHS system or an 8 mm system is used as a VTR for recording a color video signal.
TR is widely used. Especially, VHS system VTR
About 250 million units have been spread all over the world, and they are widely used at home on a daily basis. 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 converted into a low frequency band and recorded on a magnetic tape. There is. The recording / reproducing system is described in, for example, Yokoyama, “Home Video Technology,” edited by Japan Broadcasting Corporation and Sugaya, SMPTE Journal, March 1986, pages 301 to 309.

[0003]

However, in these conventional VTRs, in particular, since the color signals are converted into the low frequency range and recorded, the band and SN ratio of the reproduced color signals are different from those of the reproduced luminance signals. In comparison with the band and the SN ratio, the imbalance, that is, the quality of the color signal is poor, and the color signal limits the image quality during reproduction. 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 particular, when dubbing or editing is performed, deterioration of image quality becomes severe from a place where color saturation is high, which is a big problem.

For example, in the SVHS-VTR, the horizontal resolution of the luminance signal during reproduction is about 400 lines (5 MH).
z), the SN ratio is about 50 dB, while the horizontal resolution of the color signal is about 28, and the SN ratio is about 45 dB for AM and PM.
Is about 43 dB, which is a very low value of the quality of the color signal with respect to the luminance signal. NTSC ground wave, satellite broadcast wave,
In order to reproduce the quality of video sources such as CATV and video cameras more faithfully, M2 used for business is used.
The horizontal resolution of reproduced color signals is about 56 lines (twice that of the conventional 28 lines) or more, S
The N ratio is desired to be about 48 dB to 50 dB or more for both AM and PM.

In view of the above points, the present invention is a conventional household V
VT that records and reproduces wideband color signals with higher SN than TR
The purpose is to provide R.

[0006]

In order to achieve the above-mentioned object, the present invention achieves the above object, and a conversion circuit for converting an input color video signal into a luminance signal, a carrier color signal and two color difference signals, and frequency-modulating the luminance signal. A first frequency modulation circuit, a low-frequency conversion circuit for low-frequency converting the carrier color signal, a pre-filter circuit for obtaining a line-sequential color-difference signal from the two color-difference signals,
A time-axis reference signal adding circuit for adding a time-axis reference signal to the line-sequential color difference signal, a second frequency modulation circuit for frequency-modulating the output signal of the time-axis reference signal adding 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 pair. A second magnetic head for recording the frequency-modulated line-sequential color difference signal output from the second frequency modulation circuit between two signal recording tracks to be recorded by A Y / C time axis error correction circuit for obtaining a reproduction line sequential color signal by removing a time axis error from the reproduction luminance signal,
The reproduction line sequential color signal is input and a post filter circuit that outputs two complementary color difference signals is provided.

Further, a circuit for adding an identification signal indicating that the line-sequential color signal passes through the pre-filter circuit or the post-filter circuit is provided.

[0008]

According to the present invention, with the above structure, one new track is newly added between two tracks in which the conventional color video signal is recorded in one frame period of the video signal (one rotation period of the rotary cylinder). Since the line-sequential color-difference signal having the time-base reference signal is frequency-modulated by another head and recorded by another head, a higher S
N wideband color signals are reproduced.

During reproduction, for example, if the FM-modulated new color signal is reproduced during a half-rotation period of the rotary cylinder, a pair with the conventional luminance signal is output, and the FM-modulated new color signal is reproduced. Otherwise, if the conventional luminance signal and conventional low-frequency conversion color signal are output as a pair, the conventional VT
A new recording type VTR without the need to make any changes to R
It is possible to ensure signal reproduction compatibility between the VTR and the conventional recording method VTR.
In addition, in this method, this F
Even if the M-modulated color signal is not reproduced, the conventional low-frequency conversion color signal can be used.

Further, since the line-sequential color difference signal has a time base reference signal, the Y / C time base error is corrected at the time of reproduction, so that a calm reproduced image free from image fluctuation due to jitter can be obtained.

Further, since the identification signal indicating that the line-sequential color signal passes through the pre-filter or the post-filter is added, color blurring of the line-sequential color signal in the vertical direction can be prevented especially at the time of dubbing.

[0012]

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 is 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 signal and C signal input 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 delayed by the one-field memory circuit 5 by one field period of the video signal, linearly or nonlinearly emphasized by the FM modulation circuit 6, and then FM-modulated. 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 added to the FM-modulated Y signal in the adder circuit 8, and the recording amplifier 9 Up to

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 includes three cascaded 1-line (1H) delay circuits (not shown) 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.
Is.

Inside the pre-filter circuit 11,
Two color difference signals, which are addition outputs of these three multiplication circuits, can be switched between outputs for each horizontal synchronization period length by a 1H (1H = 1 horizontal synchronization period length) switcher circuit (not shown). So-called color signals are converted into line-sequential color difference signals from which aliasing distortion has been removed. In general, when passing through the above-mentioned pre-filter, the color signal causes a slight amount of so-called color fringing in the vertical direction. Therefore, some measure is required to reduce the color fringing in the vertical direction. In particular, when dubbing is repeated for editing, the color fringing in the vertical direction is piled up, which gradually becomes a problem.

As a solution to this problem, the first conceivable solution is to create a mode in which the pre-filter does not pass after the second time, such as during dubbing. However, there is a high possibility that the user will be confused during use. So it's actually difficult to introduce.

Second, there is a method of improving the cutoff characteristic in the vertical direction of the screen by forming a higher-order prefilter in which the number of stages of the line memory inside the prefilter is increased. This method is also an effective method, but if the dubbing is repeated many times, color fringing gradually increases.

As a third method, recently, three-dimensional Y / C is used.
A method of constructing a logical pre-filter that adaptively removes color fringing is effective based on the same idea that is being put to practical use in separation circuits, but it seems that it will take some time to realize it. Be done.

Therefore, in the present embodiment, as a method for surely preventing the spread of color bleeding, once the pre-filter has passed, an identification signal indicating that the pre-filter has passed is provided in the pre-filter within the vertical synchronization period of the color signal. Added to. When the identification signal indicating that the color has passed through the pre-filter is added to the color signal input to the pre-filter, the operation of the pre-filter is as follows. The color difference signal is only switched every 1H.

The line-sequential color difference signal output of the pre-filter circuit 11 is input to the time-axis reference signal adding circuit 12, and the line-sequential color signal is output using the time-axis information of the synchronization signal of the luminance signal which is the output of the switcher circuit 4. After the horizontal synchronizing signal is added within the horizontal synchronizing period, the output is turned on / off and output every half rotation period of the rotary cylinder. Next, the signal is input to the FM modulation circuit 13, subjected to linear or non-linear emphasis, then FM-modulated, and reaches the recording amplifier 14.

As described above, in this embodiment, the field skipped line-sequential color difference signal is FM recorded as the new recording signal. The baseband band of this field-skip line sequential color difference signal is 1 MHz (horizontal resolution 80
If the SN ratio of AM and PM is 48 dB or more, the image quality of the conventional low-frequency conversion carrier color signal is about 28 (horizontal resolution, about 45 dB of AM).
B and PM are far higher than about 43 dB), and the image quality is sufficient from the viewpoint of human visual characteristics.

Here, in FIG. 1, 15 is a rotary cylinder, 16 is its rotation direction, 17 is a magnetic tape, and 18 is its running direction. Also, 19, 2
Reference numerals 0 and 21 respectively denote magnetic heads having different azimuth angles. The magnetic tape 17 is wound about 180 degrees or more around a rotating cylinder, and the three magnetic heads are so-called helical scan type VTRs that obliquely scan the magnetic tape 17.

The output of the above-described recording amplifier 9 is passed through a well-known rotary transformer to two magnetic heads 19 and 20 arranged symmetrically with respect to each other on the circumference of the rotary cylinder 15 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.

Here, the output of the recording amplifier 9 is set to a recording level where the recording current value of the magnetic heads 19 and 20 is almost the maximum at the reproduction output from the magnetic tape, that is, a so-called saturated recording level. On the other hand, the recording amplifier 14
Is set to a recording level at which the recording current value of the magnetic 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 magnetic head 21 is lower than the supersaturation recording level, even if the third signal recording track overlaps the first signal recording track,
The first signal is not completely erased, it is possible to leave the first signal in the second signal track.

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 rotation of the rotary cylinder, and further, compared with the conventional low-frequency conversion color signal. It is also possible to record and reproduce a high quality color signal by using one newly formed track.

Therefore, even if the tape recorded by the VTR of this embodiment is reproduced by the conventional SVHS system or VHS system VTR, the signal is recorded even by the conventional VTR system, which hinders the reproduction of the color video signal. Does not occur.

FIG. 2 shows an example of the recording track pattern. Here, a case where the present invention is applied to the long-time recording mode (EP mode) of the SVHS system VTR will be described. In this case, the magnetic tape is drambed by the capstan motor during the period in which the rotary cylinder makes a half rotation.
Move 9.3 μm. The head track width and azimuth angle of the magnetic heads 19 and 21 are 26 and
Micron meter +6 degrees and 18 micron meter -15 degrees. The head track width and the azimuth angle of the magnetic head 20 are 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
The angle is not particularly limited to the above-mentioned example, and it may be any angle as long as there is little crosstalk interference from adjacent tracks and a desired frequency characteristic can be obtained with a high SN ratio in relation to other magnetic heads. Here, by selecting the azimuth angle of the recording track T2 (-15) which is nearly perpendicular to the orientation direction of the magnetic tape, it is possible to obtain a higher reproduction output at a short wavelength. It is a well-known experimental fact regarding the azimuth angle of the recording track and the reproduction output with respect to the orientation direction of the magnetic tape.

Further, in the recording pattern, the signals of adjacent tracks are separated by Y / C which is separated from each other by within 2 to 5H.
If signals such as signals that have a correlation with the adjacent Y and C signals are selected, crosstalk interference from adjacent tracks during playback can be reduced by the principle of triangular noise in FM demodulation during playback. Is.

Next, FIG. 3 shows an explanatory view of the principle of the track pattern formation of FIG. In FIG. 3, the magnetic head 21
In order to leave a recording track of 8 .mu.m, the relative height of the lower end of the magnetic head 19 is lowered by 4 .mu.m 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 the present invention according to a conventional SVHS system VTR.
When applied to. 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 11 MHz or higher. Here, 8 MH
FM color signals are recorded and reproduced in the band from z to 11 MHz. In order to satisfactorily record and reproduce the FM color signal, it is sufficient if the CN ratio of the reproduced carrier at the upper clip frequency of the FM signal is about 35 dB (noise band 30 kHz) or more.

The feasibility of the present invention has been empirically demonstrated by SVHS.
It was confirmed that it is possible to secure a CN ratio of 35 dB or more in the vicinity of 11 MHz with a recording track width of 8 μm by using a magnetic tape for recording. Here, the recording band of the FM color signal is set from 8 MHz to 11 MHz, but even in the band of 1 MHz to 4 MHz, even if it is 5.5 MHz to 8.5 MHz, which is the same as in the case of VHS, the azimuth loss effect is used to generate the FM luminance signal. The FM color signal can share the band.

As in the case of the SVHS system, FIG.
Shows the case where the present invention is applied to a conventional VHS system VTR. The FM luminance signal is used in the band of about 1 MHz to about 6 MHz, and no signal is recorded in the band of 6 MHz or higher. Here, 5.5MHz to 8.5MH
The FM color signal is recorded and reproduced in the z band. In order to satisfactorily record and reproduce the FM color signal, it is sufficient if the CN ratio of the reproduced carrier at the upper clip frequency of the FM signal is about 35 dB (noise band 30 kHz) or more.

The feasibility of the present invention has been experimentally confirmed by using a magnetic tape for VHS, it is possible to secure a CN ratio of around 8 MHz at 35 dB or more with a recording track width of 8 μm. Was done. Further, even when the bands of the FM luminance signal and the FM chrominance signal overlap with each other, it is possible to reduce the crosstalk interference to the extent that it is not a practical problem due to the azimuth loss effect between the recording tracks. Here, the recording band of the FM color signal is changed from 5 MHz to 7 MHz.
Although the frequency is set to MHz, the FM luminance signal and the FM chrominance signal can share the band even in the band of 2 MHz to 4 MHz by utilizing the azimuth loss effect.

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. Also, the second
Similarly, the output of the magnetic head 21 is also amplified by the reproducing head amplifier 28 through the rotary transformer.

The output of the reproducing head amplifier 22 is the BPF2.
3, only the FM luminance signal is extracted here, demodulated to a baseband signal by the FM demodulation circuit 24, and then deemphasized. Then, the output of the FM demodulation circuit 24 is delayed in the 1-field memory circuit 25 by 1 field period.

The output of the reproducing head amplifier 22 is B
After reaching the PF 26, the low-frequency-converted carrier color signal is extracted and converted to the original NTSC signal frequency by the frequency conversion circuit 27, and then the 1-field memory circuit 2
It is input to the switcher circuit 35 after being delayed by one field period at 8.

The output of the reproducing head amplifier 29 is BPF3.
0, the FM color signal is extracted here, demodulated to a baseband signal by the FM demodulation circuit 31, and then deemphasized. Further, the output of the FM demodulation circuit 31 is Y /
It is input to the C time difference correction circuit 32. In the Y / C time difference correction circuit 32, the horizontal demodulation signal added to the line sequential color signal in the time axis reference signal addition circuit 12 and the FM demodulation circuit 2
The time difference between the luminance signal and the chrominance signal (Y / C time difference) is corrected using the time axis information of the reproduced luminance signal synchronizing signal, which is the output of No. 4, to bring it closer to zero.

The signal corrected by the Y / C time difference correction circuit 32 is input to the post filter circuit 33 and subjected to the same signal processing as that performed by the prefilter circuit 11, and a set of (RY) ) Signal and the (BY) signal, and then, the quadrature two-layer modulation circuit 34 performs the quadrature two-layer modulation and the carrier color signal is input to the switcher circuit 35. In general,
When the signal passes through the post filter circuit described above, the color signal slightly causes so-called color fringing in the vertical direction as in the case of the pre-filter circuit. Therefore, the line memory is increased to reduce the color fringing in the vertical direction. , It is effective to configure a higher-order pre-filter circuit.

If dubbing is repeated for editing, color bleeding in the vertical direction is accumulated, which causes a problem.
In the present embodiment, once the post filter has passed, an identification signal indicating that the post filter has passed is added within the vertical synchronizing period of the color signal in the post filter circuit. If the color signal input to the post filter circuit is added with an identification signal indicating that it has passed through the post filter circuit, the operation of the post filter circuit is that it does not pass through the addition circuit using the line memory. , The color difference signals are simply switched every 1H.

In addition, in the same way as the method which has been put to practical use in the Y / C separation circuit in recent years, the correlation detection of the luminance signal and the color signal in the horizontal direction, the vertical direction and the time axis direction is performed, and the color blur is adaptively detected. It is also possible to configure a logical post filter that eliminates the above.

The switcher circuit 35 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 signal converted in frequency by the frequency conversion circuit 27 is selected as the output of the switcher circuit 35. In addition, as a result of the discrimination, FM
When the color signal is being reproduced, the switcher circuit 35
Is selected as the output of the quadrature two-layer modulation circuit 34. The FM demodulation circuit 31 may determine whether or not the FM color signal is recorded, and the output selection of the switcher circuit 35 may be controlled based on the result of the determination.

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.

An experiment in which the configuration of this embodiment is applied to an SVHS type VTR is confirmed. As its effect, the horizontal resolution of reproduced color signals is 100 or more, the SN ratio is AM,
PM and 50 dB or more were obtained. Here, the line-sequential color signal is subjected to main emphasis of about X = 2, and further subjected to non-linear emphasis of about X = 3. Then, the center carrier frequency of the FM signal is set to about 9.5M.
Hz, FM frequency shift is 1.2 MHz, 8 MH
Line-sequential FM color difference signals were recorded and reproduced in the band from z to 11 MHz.

As described above, according to this embodiment, a new color signal obtained by frequency-modulating a line-sequential color difference signal having a new time axis reference signal is provided between two tracks on which a color video signal is recorded. Is recorded, so conventional home VT
Higher SN ratio than R, broadband and high quality color signal,
That is, the horizontal resolution of the reproduced color signal is about 56 (conventional 2
8 times more than 2), SN ratio is about 48 dB for both AM and PM
The above can be secured.

Moreover, at the time of reproduction, for example, if the new color signal is reproduced, the luminance signal and the new color signal are output, and if the new color signal is not reproduced, the luminance signal and the low-frequency conversion color signal are outputted. By outputting, it is possible to ensure signal reproduction compatibility between the VTR of the new recording method and the VTR of the conventional recording method without making any change to the VTR which has been widely used. 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.

Further, since the line-sequential color difference signal has a time axis reference signal, the Y / C time axis error is corrected during reproduction,
It is possible to obtain a calm reproduction image freed from the image shake by the jitter.

Further, since the identification signal indicating that the line-sequential color signal passes through the pre-filter or the post-filter is added, color blurring of the line-sequential color signal in the vertical direction can be prevented especially at the time of dubbing.

In the above embodiment, the case where the field skipped line-sequential color difference signal is FM-recorded as an example of the signal recorded between the conventional color video signal tracks has been described. ,field·
The same effect can be obtained even if recording and reproducing are performed by using two magnetic heads having the same configuration as that of the above-described embodiment using a line-sequential color difference signal that is continuous on the time axis instead of skipping.

For example, this system is an SVHS system VTR.
In the case of the standard mode in which the track pitch per field is 58 μm and the track width is relatively large, that is, the SN ratio is large with respect to the FM signal breaking limit, The recording track width of the signal is about 40 μm (recording head track width is about 47 μm), and the line-sequential color difference signal recording track width is about 18 μm (recording head track width is about 25 μm). Then, each signal is recorded in each successive field. An example of the track pattern in this case is shown in FIG.

Further, in the case of the long time mode in which the track pitch per field is 19.3 μm and the track width has a relatively small margin, that is, the SN ratio has no margin with respect to the breaking limit of the FM signal. Has a conventional signal recording track width of about 15.3 μm (recording head track width of about 23 μm) and a line-sequential color difference signal recording track width of about 8 μm (recording head track width It is possible to have a mode in which line-sequential color difference signals are recorded every other field. This recording method has already been disclosed in Japanese Patent Application No. 4-20.
No. 4811 (filed on July 31, 1992, "magnetic recording / reproducing apparatus").

Furthermore, in a VHS video movie, when a small diameter rotary cylinder having a diameter of 3/4 of a normal rotary cylinder of 62 mm is used, the number of heads is generally 62 mm. Of 2
Doubled, the cylinder is small and the number of mounting heads is 2
Doubled and more difficult to manufacture.

Therefore, according to the present invention, in the standard mode, the conventional signal recording track width is about 30 μm (the recording head track width is about 30 μm).
Since the recording track width of the line-sequential color difference signal is about 18 μm (the track width of the recording head is about 25 μm), the line-sequential color signal can be recorded every other field. It is possible to minimize the number of magnetic heads mounted on the rotary cylinder to two.

That is, since the line-sequential color-difference signal recording is performed only in the standard mode and in the field skip, the number of the line-sequential color-difference signal recording heads is one in the normal rotating cylinder having a diameter of 62 mm. Even with a small-diameter rotary cylinder that is 3/4 the diameter, it is only half that of recording continuous signals in each field. Therefore, in this case, it is a promising method for a small movie using a small diameter rotating cylinder. It should be noted that in a normal rotating cylinder having a diameter of 62 mm, both a continuous color signal and a field skip color signal are recorded and reproduced in a field, and in a small diameter rotating cylinder, only a field skip color signal is recorded and reproduced. Recording and reproduction are possible by using a field memory in the rotating cylinder system.

Further, as a signal form to be recorded, M, which is used for broadcasting / business, is used instead of the line sequential color signal.
2 system VTR adopted time axis expansion / compression system (T
The same effect can be obtained by using a color signal of CI system or CTCM system). Further, even if the color signal is digitally modulated and recorded, the same effect can be obtained.

The same effect can be obtained by recording not only the color signal but also the band-compressed luminance signal which is digitally modulated at the same time. Furthermore, it is also 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, as a signal to be newly recorded by the second magnetic head, the same effect can be obtained even in the case of a signal obtained by analog or digitally modulating all information.

The effects of these implementations are the VT of the NTSC system.
The same implementation effect can be obtained not only for R but also for a PAL VTR. That is, basically, in the NTSC VHS-VTR, the rotating cylinder has about 30
While rotating, the relative speed of the tape and head is 5.8 m / sec, while in a PAL VTR the rotating cylinder rotates about 25 revolutions per second, which is 4.85 m / sec. Therefore,
The recording frequency of the signal in the PAL system VTR is NTSC.
If the same as in the case of the system, the recording wavelength is shortened by the amount that the relative speed becomes about 5/6, and the SN of the tape head system is reduced.
The ratio deteriorates. However, originally, if the SN ratio of the tape head system in the NTSC system has a margin, or if a new FM demodulation circuit called a super limiter which is strong against FM demodulation breakage is used, there is no practical problem.

[0061]

As described above, the present invention relates to a VTR for recording / reproducing a color video signal, and frequency-modulates a line-sequential color difference signal added with a field skipped time base reference signal to record a conventional color video signal. Recording between different tracks by another head makes it possible to reproduce a high-quality color signal in a wider band with a higher SN ratio than that of a conventional home VTR. Moreover, when the magnetic tape recorded by the method of the present invention is reproduced by the conventional VTR, since the conventional low-frequency conversion color signal is also recorded, compatibility with the conventional VTR can be ensured.

Further, since the identification signal indicating that the line-sequential color signal passes through the pre-filter or the post-filter is added, it is possible to prevent the color bleeding in the vertical direction of the color signal especially at the time of dubbing. Is.

[Brief description of drawings]

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

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 diagram showing a frequency arrangement when the present embodiment is applied to an SVHS system VTR. FIG. 4B is a diagram showing a frequency arrangement when the present embodiment is applied to a VHS system VTR.

FIG. 5 is another recording track pattern diagram in this embodiment.

[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 7 low frequency conversion circuit 8 adder circuit 9 recording amplifier 10 demodulation circuit 11 prefilter Circuit 12 Time axis reference signal addition circuit 13 FM modulation circuit 14 Recording amplifier 15 Rotating cylinder 16 Rotating direction of rotating cylinder 17 Magnetic tape 18 Magnetic tape advancing direction 19 Magnetic head 20 Magnetic head 21 Magnetic head 22 Playback head amplifier 23 BPF 24 FM demodulation Circuit 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 32 Y / C time axis error correction circuit 33 Post filter circuit 34 Right-angle two-layer modulation circuit Route 35 Switcher circuit 36 Adder circuit 37 Composite color video signal output terminal 38 Component color video signal output terminal

Claims (13)

[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-pass conversion circuit for low-pass converting the carrier color signal output from the conversion circuit, and a plurality of line memories, a plurality of multipliers, an adder, and a color video signal for inputting the two color difference signals. 2 for each horizontal synchronization period
A prefilter circuit configured by a switching circuit for sequentially switching one color difference signal, a time axis reference signal adding circuit for adding a time axis reference signal to the line sequential color difference signal output from the prefilter circuit, and the time axis reference A second frequency modulation circuit that frequency-modulates the output signal of the signal addition circuit, an addition circuit that adds the low-frequency-converted carrier color signal and the frequency-modulated luminance signal, and a color image output from the addition circuit. A frequency modulation which is an output of the second frequency modulation circuit between a first magnetic head pair for recording and reproducing a signal on a magnetic recording medium and two signal recording tracks for recording by the first magnetic head pair. A second magnetic head for recording the reproduced line-sequential color difference signal, and a reproduction line for removing a time-axis error from a reproduction luminance signal by using the time-axis reference signal during reproduction. A Y / C time axis error correction circuit for obtaining a next color signal, a plurality of line memories, a plurality of multipliers, an adder, which inputs the reproduction line sequential color signal and outputs two complementary color difference signals, and A color video signal magnetic recording / reproducing apparatus comprising a post filter circuit configured by a switching circuit that sequentially switches for each horizontal synchronization period of a color video signal. 2. When the color difference signal passes through the pre-filter circuit during recording, the pre-filter circuit adds a discrimination signal indicating that the color difference signal has passed through the pre-filter circuit to the color difference signal. The color video signal magnetic recording / reproducing apparatus according to claim 1, further comprising an identification signal adding circuit. 3. The pre-filter passage identification signal adding circuit adds the identification signal to the color difference signal within a period corresponding to the vertical synchronizing period of the luminance signal.
A magnetic recording / reproducing apparatus for the described color video signal. 4. The pre-filter pass identification signal adding circuit adds the identification signal to the color difference signal within a period corresponding to the horizontal synchronizing period of the luminance signal.
A magnetic recording / reproducing apparatus for the described color video signal. 5. The post-filter circuit internally includes a post-filter pass identification signal adding circuit for adding a signal indicating that the post-filter circuit has passed, when the reproduced signal passes through the post-filter circuit during reproduction, to the color difference signal. A magnetic recording / reproducing apparatus for color video signals according to claim 1, characterized in that 6. The post-filter passage identification signal adding circuit comprises:
The color video signal magnetic recording / reproducing apparatus according to claim 5, wherein the identification signal is added to the color difference signal within a period corresponding to the vertical synchronization period of the luminance signal. 7. The post-filter passage identification signal adding circuit comprises:
6. The color video signal magnetic recording / reproducing apparatus according to claim 5, wherein the identification signal is added to the color difference signal within a period corresponding to the horizontal synchronizing period of the luminance signal. 8. The color video signal magnetic recording / reproducing apparatus according to claim 2, wherein the identification signal is a synchronizing signal composed of a rectangular wave. 9. The color video signal magnetic recording / reproducing apparatus according to claim 2, wherein the identification signal is a burst-like synchronizing signal composed of a sine wave. 10. The 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 luminance signal and the color signal obtained by frequency demodulating the frequency-modulated color signal recorded by the second magnetic head are added to the signal passed through the post-filter circuit, and output as a reproduced color video signal,
When the frequency-modulated color signal is not reproduced by the second magnetic head during reproduction, the frequency-modulated luminance signal reproduced by the first magnetic head is frequency-demodulated and the low-frequency-converted carrier color signal. 2. The magnetic recording / reproducing of the color video signal according to claim 1, wherein the carrier color signal whose frequency is converted to the carrier color signal of the same frequency band as that at the time of input is added and output as a reproduction color video signal. apparatus. 11. A pair of first magnetic heads are arranged on a rotary cylinder symmetrically about 180 degrees, two magnetic heads whose azimuth angles have an inverse azimuth relationship with each other, and said second magnetic head. The magnetic head is arranged on the rotary cylinder between the first magnetic head pair, and the azimuth angle is one magnetic head having an azimuth angle different from the azimuth angle of the first magnetic head pair. The color video signal magnetic recording / reproducing apparatus according to claim 1, wherein 12. A pair of first magnetic heads are arranged on a rotary cylinder symmetrically about 180 degrees, and the first magnetic head pair is two magnetic heads whose azimuth angles have an inverse azimuth relationship with each other, and The magnetic head is arranged on the rotary cylinder between the first magnetic head pair, and the two magnetic heads have an azimuth angle different from the azimuth angle of the first magnetic head pair. The color video signal magnetic recording / reproducing apparatus according to claim 1, wherein 13. 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 color video signal magnetic recording / reproducing apparatus according to claim 1.